update registry url, and cart url

Co-authored-by: matst80 <mats.tornberg@gmail.com>
Reviewed-on: https://git.tornberg.me/mats/go-cart-actor/pulls/6
Co-authored-by: Mats Törnberg <mats@tornberg.me>
Co-committed-by: Mats Törnberg <mats@tornberg.me>

.dockerignore

@@ -0,0 +1,68 @@
+# .dockerignore for go-cart-actor
+#
+# Goal: Keep Docker build context lean & reproducible.
+# Adjust as project structure evolves.
+
+# Version control & CI metadata
+.git
+.git/
+.gitignore
+.github
+
+# Local tooling / editors
+.vscode
+.idea
+*.iml
+
+# Build artifacts / outputs
+bin/
+build/
+dist/
+out/
+coverage/
+*.coverprofile
+
+# Temporary files
+*.tmp
+*.log
+tmp/
+.tmp/
+
+# Dependency/vendor caches (not used; rely on go modules download)
+vendor/
+
+# Examples / scripts (adjust if you actually need them in build context)
+examples/
+scripts/
+
+# Docs (retain README.md explicitly)
+docs/
+CHANGELOG*
+**/*.md
+!README.md
+
+# Tests (not needed for production build)
+**/*_test.go
+
+# Node / frontend artifacts (if any future addition)
+node_modules/
+
+# Docker / container metadata not needed inside image
+Dockerfile
+
+# Editor swap/backup files
+*~
+*.swp
+
+# Go race / profiling outputs
+*.pprof
+
+# Security / secret placeholders (ensure real secrets never copied)
+*.secret
+*.key
+*.pem
+
+# Keep proto and generated code (do NOT ignore proto/)
+!proto/
+
+# End of file

.gitea/workflows/build.yaml

@@ -1,30 +1,43 @@
 name: Build and Publish
-run-name: ${{ gitea.actor }} is building 🚀
+run-name: ${{ gitea.actor }} build 🚀
 on: [push]
 
 jobs:
   BuildAndDeployAmd64:
     runs-on: amd64
     steps:
-      - name: Check out repository code
+      - uses: actions/checkout@v5
-        uses: actions/checkout@v4
+      - name: Build amd64 image
-      - name: Build docker image
+        run: |
-        run: docker build --progress=plain -t registry.knatofs.se/go-cart-actor-amd64:latest .
+          docker build \
-      - name: Push to registry
+            --progress=plain \
-        run: docker push registry.knatofs.se/go-cart-actor-amd64:latest
+            -t registry.k6n.net/go-cart-actor-amd64:latest \
-      - name: Deploy to Kubernetes
+            .
+      - name: Push amd64 images
+        run: |
+          docker push registry.k6n.net/go-cart-actor-amd64:latest
+      - name: Apply deployment manifests
         run: kubectl apply -f deployment/deployment.yaml -n cart
-      - name: Rollout amd64 deployment
+      - name: Rollout amd64 backoffice deployment
-        run: kubectl rollout restart deployment/cart-actor-x86 -n cart
+        run: |
-  
+          kubectl rollout restart deployment/cart-backoffice-x86 -n cart
-  BuildAndDeploy:
+          kubectl rollout restart deployment/cart-actor-x86 -n cart
+
+  BuildAndDeployArm64:
     runs-on: arm64
     steps:
-      - name: Check out repository code
+      - uses: actions/checkout@v4
-        uses: actions/checkout@v4
+      - name: Build arm64 image
-      - name: Build docker image
+        run: |
-        run: docker build --progress=plain -t registry.knatofs.se/go-cart-actor .
+          docker build \
-      - name: Push to registry
+            --progress=plain \
-        run: docker push registry.knatofs.se/go-cart-actor
+            -t registry.k6n.net/go-cart-actor:latest \
-      - name: Rollout arm64 deployment
+            .
-        run: kubectl rollout restart deployment/cart-actor-arm64 -n cart
+      - name: Push arm64 images
+        run: |
+          docker push registry.k6n.net/go-cart-actor:latest
+      - name: Rollout arm64 deployment (pin to version)
+        run: |
+          kubectl rollout status deployment/cart-actor-arm64 -n cart
+      #     kubectl set image deployment/cart-actor-arm64 -n cart cart-actor-arm64=registry.k6n.net/go-cart-actor:${{ needs.Metadata.outputs.version }}
+      #     # kubectl rollout status deployment/cart-actor-arm64 -n cart

.gitignore

@@ -1,4 +1,5 @@
 __debug*
 go-cart-actor
 data/*.prot
-data/*.go*
+data/*.go*
+data/se/*

Dockerfile

@@ -1,17 +1,91 @@
-# syntax=docker/dockerfile:1
+# syntax=docker/dockerfile:1.7
+#
+# Multi-stage build:
+#  1. Build static binary with pinned Go version (matching go.mod).
+#  2. Copy into distroless static nonroot runtime image.
+#
+# Build args (optional):
+#   VERSION      - semantic/app version (default: dev)
+#   GIT_COMMIT   - git SHA (default: unknown)
+#   BUILD_DATE   - RFC3339 build timestamp
+#
+# Example build:
+#   docker build \
+#     --build-arg VERSION=$(git describe --tags --always) \
+#     --build-arg GIT_COMMIT=$(git rev-parse HEAD) \
+#     --build-arg BUILD_DATE=$(date -u +%Y-%m-%dT%H:%M:%SZ) \
+#     -t go-cart-actor:dev .
+#
+# If you add subpackages or directories, no Dockerfile change needed (COPY . .).
+# Ensure a .dockerignore exists to keep context lean.
 
-FROM golang:alpine AS build-stage
+############################
-WORKDIR /app
+# Build Stage
+############################
+FROM golang:1.25-alpine AS build
+WORKDIR /src
+
+# Build metadata (can be overridden at build time)
+ARG VERSION=dev
+ARG GIT_COMMIT=unknown
+ARG BUILD_DATE=unknown
+
+# Ensure reproducible static build
+# Multi-arch build args (TARGETOS/TARGETARCH provided automatically by buildx)
+ARG TARGETOS
+ARG TARGETARCH
+ENV CGO_ENABLED=0 GOOS=${TARGETOS:-linux} GOARCH=${TARGETARCH}
+
+# Dependency caching
 COPY go.mod go.sum ./
-RUN go mod download
+RUN --mount=type=cache,target=/go/pkg/mod \
+    go mod download
 
-COPY proto ./proto
+# Copy full source (relay on .dockerignore to prune)
-COPY *.go ./
+COPY . .
 
-RUN CGO_ENABLED=0 GOOS=linux go build -o /go-cart-actor
+# (Optional) If you do NOT check in generated protobuf code, uncomment generation:
+# RUN go install google.golang.org/protobuf/cmd/protoc-gen-go@latest && \
+#     go install google.golang.org/grpc/cmd/protoc-gen-go-grpc@latest && \
+#     protoc --go_out=. --go_opt=paths=source_relative \
+#            --go-grpc_out=. --go-grpc_opt=paths=source_relative \
+#            proto/*.proto
 
-FROM gcr.io/distroless/base-debian11
+# Build with minimal binary size and embedded metadata
+RUN --mount=type=cache,target=/go/build-cache \
+    go build -trimpath -ldflags="-s -w \
+    -X main.Version=${VERSION} \
+    -X main.GitCommit=${GIT_COMMIT} \
+    -X main.BuildDate=${BUILD_DATE}" \
+    -o /out/go-cart-actor ./cmd/cart
+
+RUN --mount=type=cache,target=/go/build-cache \
+    go build -trimpath -ldflags="-s -w \
+    -X main.Version=${VERSION} \
+    -X main.GitCommit=${GIT_COMMIT} \
+    -X main.BuildDate=${BUILD_DATE}" \
+    -o /out/go-cart-backoffice ./cmd/backoffice
+
+RUN --mount=type=cache,target=/go/build-cache \
+    go build -trimpath -ldflags="-s -w \
+    -X main.Version=${VERSION} \
+    -X main.GitCommit=${GIT_COMMIT} \
+    -X main.BuildDate=${BUILD_DATE}" \
+    -o /out/go-cart-inventory ./cmd/inventory
+
+############################
+# Runtime Stage
+############################
+# Using distroless static (nonroot) for minimal surface area.
+FROM gcr.io/distroless/static-debian12:nonroot AS runtime
 WORKDIR /
 
-COPY --from=build-stage /go-cart-actor /go-cart-actor
+COPY --from=build /out/go-cart-actor /go-cart-actor
-ENTRYPOINT ["/go-cart-actor"]
+COPY --from=build /out/go-cart-backoffice /go-cart-backoffice
+COPY --from=build /out/go-cart-inventory /go-cart-inventory
+
+# Document (not expose forcibly) typical ports: 8080 (HTTP), 1337 (gRPC)
+EXPOSE 8080 1337
+
+USER nonroot:nonroot
+ENTRYPOINT ["/go-cart-actor"]

Makefile

@@ -0,0 +1,132 @@
+# ------------------------------------------------------------------------------
+# Makefile for go-cart-actor
+#
+# Key targets:
+#   make protogen      - Generate protobuf + gRPC code into proto/
+#   make clean_proto   - Remove generated proto *.pb.go files
+#   make verify_proto  - Ensure no stray root-level *.pb.go files exist
+#   make build         - Build the project
+#   make test          - Run tests (verbose)
+#   make tidy          - Run go mod tidy
+#   make regen         - Clean proto, regenerate, tidy, verify, build
+#   make help          - Show this help
+#
+# Conventions:
+#   - All .proto files live in $(PROTO_DIR)
+#   - Generated Go code is emitted under $(PROTO_DIR) via go_package mapping
+#   - go_package is set to: git.tornberg.me/go-cart-actor/proto;messages
+# ------------------------------------------------------------------------------
+
+MODULE_PATH := git.tornberg.me/go-cart-actor
+PROTO_DIR   := proto
+PROTOS      := $(PROTO_DIR)/messages.proto $(PROTO_DIR)/control_plane.proto
+
+# Allow override: make PROTOC=/path/to/protoc
+PROTOC ?= protoc
+
+# Tools (auto-detect; can override)
+PROTOC_GEN_GO        ?= $(shell command -v protoc-gen-go 2>/dev/null)
+PROTOC_GEN_GO_GRPC   ?= $(shell command -v protoc-gen-go-grpc 2>/dev/null)
+
+GO        ?= go
+
+# Colors (optional)
+GREEN  := \033[32m
+RED    := \033[31m
+YELLOW := \033[33m
+RESET  := \033[0m
+
+# ------------------------------------------------------------------------------
+
+.PHONY: protogen clean_proto verify_proto tidy build test regen help check_tools
+
+help:
+	@echo "Available targets:"
+	@echo "  protogen      Generate protobuf & gRPC code"
+	@echo "  clean_proto   Remove generated *.pb.go files in $(PROTO_DIR)"
+	@echo "  verify_proto  Ensure no root-level *.pb.go files (old layout)"
+
+	@echo "  tidy          Run go mod tidy"
+	@echo "  build         Build the module"
+	@echo "  test          Run tests (verbose)"
+	@echo "  regen         Clean proto, regenerate, tidy, verify, and build"
+	@echo "  check_tools   Verify protoc + plugins are installed"
+
+check_tools:
+	@if [ -z "$(PROTOC_GEN_GO)" ] || [ -z "$(PROTOC_GEN_GO_GRPC)" ]; then \
+		echo "$(RED)Missing protoc-gen-go or protoc-gen-go-grpc in PATH.$(RESET)"; \
+		echo "Install with:"; \
+		echo "  go install google.golang.org/protobuf/cmd/protoc-gen-go@latest"; \
+		echo "  go install google.golang.org/grpc/cmd/protoc-gen-go-grpc@latest"; \
+		exit 1; \
+	fi
+	@if ! command -v "$(PROTOC)" >/dev/null 2>&1; then \
+		echo "$(RED)protoc not found. Install protoc (e.g. via package manager)$(RESET)"; \
+		exit 1; \
+	fi
+	@echo "$(GREEN)All required tools detected.$(RESET)"
+
+protogen: check_tools
+	@echo "$(YELLOW)Generating protobuf code (outputs -> ./proto)...$(RESET)"
+	$(PROTOC) -I $(PROTO_DIR) \
+	  --go_out=./pkg/messages --go_opt=paths=source_relative \
+	  --go-grpc_out=./pkg/messages --go-grpc_opt=paths=source_relative \
+	  $(PROTOS)
+	@echo "$(GREEN)Protobuf generation complete.$(RESET)"
+
+clean_proto:
+	@echo "$(YELLOW)Removing generated protobuf files...$(RESET)"
+	@rm -f $(PROTO_DIR)/*_grpc.pb.go $(PROTO_DIR)/*.pb.go
+	@rm -f *.pb.go
+	@rm -rf git.tornberg.me
+	@echo "$(GREEN)Clean complete.$(RESET)"
+
+verify_proto:
+	@echo "$(YELLOW)Verifying proto layout...$(RESET)"
+	@if ls *.pb.go >/dev/null 2>&1; then \
+		echo "$(RED)ERROR: Found root-level generated *.pb.go files (should be only under $(PROTO_DIR)/).$(RESET)"; \
+		ls -1 *.pb.go; \
+		exit 1; \
+	fi
+	@echo "$(GREEN)Proto layout OK (no root-level *.pb.go files).$(RESET)"
+
+
+
+
+
+
+
+
+
+
+
+
+
+tidy:
+	@echo "$(YELLOW)Running go mod tidy...$(RESET)"
+	$(GO) mod tidy
+	@echo "$(GREEN)tidy complete.$(RESET)"
+
+build:
+	@echo "$(YELLOW)Building...$(RESET)"
+	$(GO) build ./...
+	@echo "$(GREEN)Build success.$(RESET)"
+
+test:
+	@echo "$(YELLOW)Running tests...$(RESET)"
+	$(GO) test -v ./...
+	@echo "$(GREEN)Tests completed.$(RESET)"
+
+regen: clean_proto protogen tidy verify_proto build
+	@echo "$(GREEN)Full regenerate cycle complete.$(RESET)"
+
+# Utility: show proto sources and generated outputs
+print_proto:
+	@echo "Proto sources:"
+	@ls -1 $(PROTOS)
+	@echo ""
+	@echo "Generated files (if any):"
+	@ls -1 $(PROTO_DIR)/*pb.go 2>/dev/null || echo "(none)"
+
+# Prevent make from treating these as file targets if similarly named files appear.
+.SILENT: help check_tools protogen clean_proto verify_proto tidy build test regen print_proto

README.md

@@ -6,7 +6,7 @@ A distributed cart management system using the actor model pattern.
 
 - Go 1.24.2+
 - Protocol Buffers compiler (`protoc`)
-- protoc-gen-go plugin
+- protoc-gen-go and protoc-gen-go-grpc plugins
 
 ### Installing Protocol Buffers
 
@@ -32,17 +32,20 @@ sudo apt install protobuf-compiler
 
 ```bash
 go install google.golang.org/protobuf/cmd/protoc-gen-go@latest
+go install google.golang.org/grpc/cmd/protoc-gen-go-grpc@latest
 ```
 
 ## Working with Protocol Buffers
 
 ### Generating Go code from proto files
 
-After modifying `proto/messages.proto`, regenerate the Go code:
+After modifying any proto (`proto/messages.proto`, `proto/cart_actor.proto`, `proto/control_plane.proto`), regenerate the Go code (all three share the unified `messages` package):
 
 ```bash
 cd proto
-protoc --go_out=. --go_opt=paths=source_relative messages.proto
+protoc --go_out=. --go_opt=paths=source_relative \
+       --go-grpc_out=. --go-grpc_opt=paths=source_relative \
+       messages.proto cart_actor.proto control_plane.proto
 ```
 
 ### Protocol Buffer Messages
@@ -73,8 +76,338 @@ go build .
 go test ./...
 ```
 
+## HTTP API Quick Start (curl Examples)
+
+Assuming the service is reachable at http://localhost:8080 and the cart API is mounted at /cart.
+Most endpoints use an HTTP cookie named `cartid` to track the cart. The first request will set it.
+
+### 1. Get (or create) a cart
+```bash
+curl -i http://localhost:8080/cart/
+```
+Response sets a `cartid` cookie and returns the current (possibly empty) cart JSON.
+
+### 2. Add an item by SKU (implicit quantity = 1)
+```bash
+curl -i --cookie-jar cookies.txt http://localhost:8080/cart/add/TEST-SKU-123
+```
+Stores cookie in `cookies.txt` for subsequent calls.
+
+### 3. Add an item with explicit payload (country, quantity)
+```bash
+curl -i --cookie cookies.txt \
+  -H "Content-Type: application/json" \
+  -d '{"sku":"TEST-SKU-456","quantity":2,"country":"se"}' \
+  http://localhost:8080/cart/
+```
+
+### 4. Change quantity of an existing line
+(First list the cart to find `id` of the line; here we use id=1 as an example)
+```bash
+curl -i --cookie cookies.txt \
+  -X PUT -H "Content-Type: application/json" \
+  -d '{"id":1,"quantity":3}' \
+  http://localhost:8080/cart/
+```
+
+### 5. Remove an item
+```bash
+curl -i --cookie cookies.txt -X DELETE http://localhost:8080/cart/1
+```
+
+### 6. Set entire cart contents (overwrites items)
+```bash
+curl -i --cookie cookies.txt \
+  -X POST -H "Content-Type: application/json" \
+  -d '{"items":[{"sku":"TEST-SKU-AAA","quantity":1,"country":"se"},{"sku":"TEST-SKU-BBB","quantity":2,"country":"se"}]}' \
+  http://localhost:8080/cart/set
+```
+
+### 7. Add a delivery (provider + optional items)
+If `items` is empty or omitted, all items without a delivery get this one.
+```bash
+curl -i --cookie cookies.txt \
+  -X POST -H "Content-Type: application/json" \
+  -d '{"provider":"standard","items":[1,2]}' \
+  http://localhost:8080/cart/delivery
+```
+
+### 8. Remove a delivery by deliveryId
+```bash
+curl -i --cookie cookies.txt -X DELETE http://localhost:8080/cart/delivery/1
+```
+
+### 9. Set a pickup point for a delivery
+```bash
+curl -i --cookie cookies.txt \
+  -X PUT -H "Content-Type: application/json" \
+  -d '{"id":"PUP123","name":"Locker 5","address":"Main St 1","city":"Stockholm","zip":"11122","country":"SE"}' \
+  http://localhost:8080/cart/delivery/1/pickupPoint
+```
+
+### 10. Checkout (returns HTML snippet from Klarna)
+```bash
+curl -i --cookie cookies.txt http://localhost:8080/cart/checkout
+```
+
+### 11. Using a known cart id directly (bypassing cookie)
+If you already have a cart id (e.g. 1720000000000000):
+```bash
+CART_ID=1720000000000000
+curl -i http://localhost:8080/cart/byid/$CART_ID
+curl -i -X POST -H "Content-Type: application/json" \
+  -d '{"sku":"TEST-SKU-XYZ","quantity":1,"country":"se"}' \
+  http://localhost:8080/cart/byid/$CART_ID
+```
+
+### 12. Clear cart cookie (forces a new cart on next request)
+```bash
+curl -i --cookie cookies.txt -X DELETE http://localhost:8080/cart/
+```
+
+Tip: Use `--cookie-jar` and `--cookie` to persist the session across multiple commands:
+```bash
+curl --cookie-jar cookies.txt http://localhost:8080/cart/
+curl --cookie cookies.txt http://localhost:8080/cart/add/TEST-SKU-123
+```
+
 ## Important Notes
 
-- Always regenerate protobuf Go code after modifying `.proto` files
+- Always regenerate protobuf Go code after modifying any `.proto` files (messages/cart_actor/control_plane)
 - The generated `messages.pb.go` file should not be edited manually
-- Make sure your PATH includes the protoc-gen-go binary location (usually `$GOPATH/bin`)
+- Make sure your PATH includes the protoc-gen-go binary location (usually `$GOPATH/bin`)
+
+---
+
+## Architecture Overview
+
+The system is a distributed, sharded (by cart id) actor model implementation:
+
+- Each cart is a grain (an in‑memory struct `*CartGrain`) that owns and mutates its own state.
+- A **local grain pool** holds grains owned by the node.
+- A **synced (cluster) pool** (`SyncedPool`) coordinates multiple nodes and exposes local or remote grains through a uniform interface (`GrainPool`).
+- All inter‑node communication is gRPC:
+  - Cart mutation & state RPCs (CartActor service).
+  - Control plane RPCs (ControlPlane service) for membership, ownership negotiation, liveness, and graceful shutdown.
+
+### Key Processes
+
+1. Client HTTP request (or gRPC client) arrives with a cart identifier (cookie or path).
+2. The pool resolves ownership:
+   - If local grain exists → use it.
+   - If a remote host is known owner → a remote grain proxy (`RemoteGrainGRPC`) is used; it performs gRPC calls to the owning node.
+   - If ownership is unknown → node attempts to claim ownership (quorum negotiation) and spawns a local grain.
+3. Mutation is executed via the **mutation registry** (registry wraps domain logic + optional totals recomputation).
+4. Updated state returned to caller; ownership preserved unless relinquished later (not yet implemented to shed load).
+
+---
+
+## Grain & Mutation Model
+
+- `CartGrain` holds items, deliveries, pricing aggregates, and checkout/order metadata.
+- All mutations are registered via `RegisterMutation[T]` with signature:
+  ```
+  func(*CartGrain, *T) error
+  ```
+- `WithTotals()` flag triggers automatic recalculation of totals after successful handlers.
+- The old giant `switch` in `CartGrain.Apply` has been replaced by registry dispatch; unregistered mutations fail fast.
+- Adding a mutation:
+  1. Define proto message.
+  2. Generate code.
+  3. Register handler (optionally WithTotals).
+  4. Add gRPC RPC + request wrapper if the mutation must be remotely invokable.
+  5. (Optional) Add HTTP endpoint mapping to the mutation.
+
+---
+
+## Local Grain Pool
+
+- Manages an in‑memory map `map[CartId]*CartGrain`.
+- Lazy spawn: first mutation or explicit access triggers `spawn(id)`.
+- TTL / purge loop periodically removes expired grains unless they changed recently (basic memory pressure management).
+- Capacity limit (`PoolSize`); oldest expired grain evicted first when full.
+
+---
+
+## Synced (Cluster) Pool
+
+`SyncedPool` wraps a local pool and tracks:
+
+- `remoteHosts`: known peer nodes (gRPC connections).
+- `remoteIndex`: mapping of cart id → remote grain proxy (`RemoteGrainGRPC`) for carts owned elsewhere.
+
+Responsibilities:
+
+1. Discovery integration (via a `Discovery` interface) adds/removes hosts.
+2. Periodic ping health checks (ControlPlane.Ping).
+3. Ring-based deterministic ownership:
+   - Ownership is derived directly from the consistent hashing ring (no quorum RPC or `ConfirmOwner`).
+4. Remote spawning:
+   - When a remote host reports its cart ids (`GetCartIds`), the pool creates remote proxies for fast routing.
+
+---
+
+## Remote Grain Proxies
+
+A `RemoteGrainGRPC` implements the `Grain` interface but delegates:
+
+- `Apply` → Specific CartActor per‑mutation RPC (e.g., `AddItem`, `RemoveItem`) constructed from the mutation type. (Legacy envelope removed.)
+- `GetCurrentState` → `CartActor.GetState`.
+
+Return path:
+
+1. gRPC reply (CartMutationReply / StateReply) → proto `CartState`.
+2. `ToCartState` / mapping reconstructs a local `CartGrain` snapshot for callers expecting grain semantics.
+
+---
+
+## Control Plane (Inter‑Node Coordination)
+
+Defined in `proto/control_plane.proto`:
+
+| RPC | Purpose |
+|-----|---------|
+| `Ping` | Liveness; increments missed ping counter if failing. |
+| `Negotiate` | Merges membership views; used after discovery events. |
+| `GetCartIds` | Enumerate locally owned carts for remote index seeding. |
+| `Closing` | Graceful shutdown notice; peers remove host & associated remote grains. |
+
+### Ownership / Quorum Rules
+
+- If total participating hosts < 3 → all must accept.
+- Otherwise majority acceptance (`ok >= total/2`).
+- On failure → local tentative grain is removed (rollback to avoid split‑brain).
+
+---
+
+## Request / Mutation Flow Examples
+
+### Local Mutation
+1. HTTP handler parses request → determines cart id.
+2. `SyncedPool.Apply`:
+   - Finds local grain (or spawns new after quorum).
+   - Executes registry mutation.
+3. Totals updated if flagged.
+4. HTTP response returns updated JSON (via `ToCartState`).
+
+### Remote Mutation
+1. `SyncedPool.Apply` sees cart mapped to a remote host.
+2. Routes to `RemoteGrainGRPC.Apply`.
+3. Remote node executes mutation locally and returns updated state over gRPC.
+4. Proxy materializes snapshot locally (not authoritative, read‑only view).
+
+### Checkout (Side‑Effecting, Non-Pure)
+- HTTP `/checkout` uses current grain snapshot to build payload (pure function).
+- Calls Klarna externally (not a mutation).
+- Applies `InitializeCheckout` mutation to persist reference + status.
+- Returns Klarna order JSON to client.
+
+---
+
+## Scaling & Deployment
+
+- **Horizontal scaling**: Add more nodes; discovery layer (Kubernetes / service registry) feeds hosts to `SyncedPool`.
+- **Sharding**: Implicit by cart id hash. Ownership is first-claim with quorum acceptance.
+- **Hot spots**: A single popular cart remains on one node; for heavy multi-client concurrency, future work could add read replicas or partitioning (not implemented).
+- **Capacity tuning**: Increase `PoolSize` & memory limits; adjust TTL for stale cart eviction.
+
+### Adding Nodes
+1. Node starts gRPC server (CartActor + ControlPlane).
+2. After brief delay, begins discovery watch; on event:
+   - New host → dial + negotiate → seed remote cart ids.
+3. Pings maintain health; failed hosts removed (proxies invalidated).
+
+---
+
+## Failure Handling
+
+| Scenario | Behavior |
+|----------|----------|
+| Remote host unreachable | Pings increment `MissedPings`; after threshold host removed. |
+| Ownership negotiation fails | Tentative local grain discarded. |
+| gRPC call error on remote mutation | Error bubbled to caller; no local fallback. |
+| Missing mutation registration | Fast failure with explicit error message. |
+| Partial checkout (Klarna fails) | No local state mutation for checkout; client sees error; cart remains unchanged. |
+
+---
+
+## Mutation Registry Summary
+
+- Central, type-safe registry prevents silent omission.
+- Each handler:
+  - Validates input.
+  - Mutates `*CartGrain`.
+  - Returns error for rejection.
+- Automatic totals recomputation reduces boilerplate and consistency risk.
+- Coverage test (add separately) can enforce all proto mutations are registered.
+
+---
+
+## gRPC Interfaces
+
+- **CartActor**: Per-mutation unary RPCs + `GetState`. (Checkout logic intentionally excluded; handled at HTTP layer.)
+- **ControlPlane**: Cluster coordination (Ping, Negotiate, GetCartIds, Closing) — ownership now ring-determined (no ConfirmOwner).
+
+**Ports** (default / implied):
+- CartActor & ControlPlane share the same gRPC server/listener (single port, e.g. `:1337`).
+- Legacy frame/TCP code has been removed.
+
+---
+
+## Security & Future Enhancements
+
+| Area | Potential Improvement |
+|------|------------------------|
+| Transport Security | Add TLS / mTLS to gRPC servers & clients. |
+| Auth / RBAC | Intercept CartActor RPCs with auth metadata. |
+| Backpressure | Rate-limit remote mutation calls per host. |
+| Observability | Add per-mutation Prometheus metrics & tracing spans. |
+| Ownership | Add lease timeouts / fencing tokens for stricter guarantees. |
+| Batch Ops | Introduce batch mutation RPC or streaming updates (WatchState). |
+| Persistence | Reintroduce event log or snapshot persistence layer if durability required. |
+
+---
+
+## Adding a New Node (Operational Checklist)
+
+1. Deploy binary/container with same proto + registry.
+2. Expose gRPC port.
+3. Ensure discovery lists the new host.
+4. Node dials peers, negotiates membership.
+5. Remote cart proxies seeded.
+6. Traffic routed automatically based on ownership.
+
+---
+
+## Adding a New Mutation (Checklist Recap)
+
+1. Define proto message (+ request wrapper & RPC if remote invocation needed).
+2. Regenerate protobuf code.
+3. Implement & register handler (`RegisterMutation`).
+4. Add client (HTTP/gRPC) endpoint.
+5. Write unit + integration tests.
+6. (Optional) Add to coverage test list and docs.
+
+---
+
+## High-Level Data Flow Diagram (Text)
+
+```
+Client -> HTTP Handler -> SyncedPool -> (local?) -> Registry -> Grain State
+                       \-> (remote?) -> RemoteGrainGRPC -> gRPC -> Remote CartActor -> Registry -> Grain
+ControlPlane: Discovery Events <-> Negotiation/Ping <-> SyncedPool state (ring determines ownership)
+```
+
+---
+
+## Troubleshooting
+
+| Symptom | Likely Cause | Action |
+|---------|--------------|--------|
+| New cart every request | Secure cookie over plain HTTP or not sending cookie jar | Disable Secure locally or use HTTPS & proper curl `-b` |
+| Unsupported mutation error | Missing registry handler | Add `RegisterMutation` for that proto |
+| Ownership imbalance | Ring host distribution skew or rapid host churn | Examine `cart_ring_host_share`, `cart_ring_hosts`, and logs for host add/remove; rebalance or investigate instability |
+| Remote mutation latency | Network / serialization overhead | Consider batching or colocating hot carts |
+| Checkout returns 500 | Klarna call failed | Inspect logs; no grain state mutated |
+
+---

TODO.md

@@ -0,0 +1,245 @@
+# TODO / Roadmap
+
+A living roadmap for improving the cart actor system. Focus areas:
+1. Reliability & correctness
+2. Simplicity of mutation & ownership flows
+3. Developer experience (DX)
+4. Operability (observability, tracing, metrics)
+5. Performance & scalability
+6. Security & multi-tenant readiness
+
+---
+
+## 1. Immediate Next Steps (High-Leverage)
+
+| Priority | Task | Goal | Effort | Owner | Notes |
+|----------|------|------|--------|-------|-------|
+| P0 | Add mutation registry coverage test | Ensure no unregistered mutations silently fail | S |  | Failing fast in CI |
+| P0 | Add decodeJSON helper + 400 mapping for EOF | Reduce noisy 500 logs | S |  | Improves client API clarity |
+| P0 | Regenerate protos & prune unused messages (CreateCheckoutOrder, Checkout RPC remnants) | Eliminate dead types | S |  | Avoid confusion |
+| P0 | Add integration test: multi-node ownership negotiation | Validate quorum logic | M |  | Spin up 2–3 nodes ephemeral |
+| P1 | Export Prometheus metrics for per-mutation counts & latency | Operability | M |  | Wrap registry handlers |
+| P1 | Add graceful shutdown ordering (Closing → wait for acks → stop gRPC) | Reduce in-flight mutation failures | S |  | Add context cancellation |
+| P1 | Add coverage for InitializeCheckout / OrderCreated flows | Checkout reliability | S |  | Simulate Klarna stub |
+| P2 | Add optional batching client (apply multiple mutations locally then persist) | Performance | M |  | Only if needed |
+
+---
+
+## 2. Simplification Opportunities
+
+### A. RemoteGrain Proxy Mapping
+Current: manual switch building each RPC call.
+Simplify by:
+- Generating a thin client adapter from proto RPC descriptors (codegen).
+- Or using a registry similar to mutation registry but for “outbound call constructors”.
+Benefit: adding a new mutation = add proto + register server handler + register outbound invoker (no switch edits).
+
+### B. Ownership Negotiation
+Current: ad hoc quorum rule in `SyncedPool`.
+Simplify:
+- Introduce explicit `OwnershipLease{holder, expiresAt, version}`.
+- Use monotonic version increment—reject stale ConfirmOwner replies.
+- Optional: add randomized backoff to reduce thundering herd on contested cart ids.
+
+### C. CartId Handling
+Current: ephemeral 16-byte array with trimmed string semantics.
+Simplify:
+- Use ULID / UUIDv7 (time-ordered, collision-resistant) for easier external correlation.
+- Provide helper `NewCartIdString()` and keep internal fixed-size if still desired.
+
+### D. Mutation Signatures
+Current: registry assumes `func(*CartGrain, *T) error`.
+Extension option: allow pure transforms returning a delta struct (for audit/logging):
+```
+type MutationResult struct {
+  Changed bool
+  Events  []interface{}
+}
+```
+Only implement if auditing/event-sourcing reintroduced.
+
+---
+
+## 3. Developer Experience Improvements
+
+| Task | Rationale | Approach |
+|------|-----------|----------|
+| Makefile targets: `make run-single`, `make run-multi N=3` | Faster local cluster spin-up | Docker compose or background “mini cluster” scripts |
+| Template for new mutation (generator) | Reduce boilerplate | `go:generate` scanning proto for new RPCs |
+| Lint config (golangci-lint) | Catch subtle issues early | Add `.golangci.yml` |
+| Pre-commit hook for proto regeneration check | Avoid stale generated code | Script compares git diff after `make protogen` |
+| Example client (Go + curl snippets auto-generated) | Onboarding | Codegen a markdown from proto comments |
+
+---
+
+## 4. Observability / Metrics / Tracing
+
+| Area | Metric / Trace | Notes |
+|------|----------------|-------|
+| Mutation registry | `cart_mutations_total{type,success}`; duration histogram | Wrap handler |
+| Ownership negotiation | `cart_ownership_attempts_total{result}` | result=accepted,rejected,timeout |
+| Remote latency | `cart_remote_mutation_seconds{method}` | Use client interceptors |
+| Pings | `cart_remote_missed_pings_total{host}` | Already count, expose |
+| Checkout flow | `checkout_attempts_total`, `checkout_failures_total` | Differentiate Klarna vs internal errors |
+| Tracing | Span: HTTP handler → SyncedPool.Apply → (Remote?) gRPC → mutation handler | Add OpenTelemetry instrumentation |
+
+---
+
+## 5. Performance & Scalability
+
+| Concern | Idea | Trade-Off |
+|---------|------|-----------|
+| High mutation rate on single cart | Introduce optional mutation queue (serialize explicitly) | Slight latency increase per op |
+| Remote call overhead | Add client-side gRPC pooling & per-host circuit breaker | Complexity vs resilience |
+| TTL purge efficiency | Use min-heap or timing wheel instead of slice scan | More code, better big-N performance |
+| Batch network latency | Add `BatchMutate` RPC (list of mutations applied atomically) | Lost single-op simplicity |
+
+---
+
+## 6. Reliability Features
+
+| Feature | Description | Priority |
+|---------|-------------|----------|
+| Lease fencing token | Include `ownership_version` in all remote mutate requests | M |
+| Retry policy | Limited retry for transient network errors (idempotent mutations only) | L |
+| Dead host reconciliation | On host removal, proactively attempt re-acquire of its carts | M |
+| Drain mode | Node marks itself “draining” → refuses new ownership claims | M |
+
+---
+
+## 7. Security & Hardening
+
+| Area | Next Step | Detail |
+|------|-----------|--------|
+| Transport | mTLS on gRPC | Use SPIFFE IDs or simple CA |
+| AuthN/AuthZ | Interceptor enforcing service token | Inject metadata header |
+| Input validation | Strengthen JSON decode responses | Disallow unknown fields globally |
+| Rate limiting | Per-IP / per-cart throttling | Guard hotspot abuse |
+| Multi-tenancy | Tenant id dimension in cart id or metadata | Partition metrics & ownership |
+
+---
+
+## 8. Testing Strategy Enhancements
+
+| Gap | Improvement |
+|-----|------------|
+| No multi-node integration test in CI | Spin ephemeral in-process servers on randomized ports |
+| Mutation regression | Table-driven tests auto-discover handlers via registry |
+| Ownership race | Stress test: concurrent Apply on same new cart id from N goroutines |
+| Checkout external dependency | Klarna mock server (HTTptest) + deterministic responses |
+| Fuzzing | Fuzz `BuildCheckoutOrderPayload` & mutation handlers for panics |
+
+---
+
+## 9. Cleanup / Tech Debt
+
+| Item | Action |
+|------|--------|
+| Remove deprecated proto remnants (CreateCheckoutOrder, Checkout RPC) | Delete & regenerate |
+| Consolidate duplicate tax computations | Single helper with tax config |
+| Delivery price hard-coded (4900) | Config or pricing strategy interface |
+| Mixed naming (camel vs snake JSON historically) | Provide stable external API doc; accept old forms if needed |
+| Manual remote mutation switch (if still present) | Replace with generated outbound registry |
+| Mixed error responses (string bodies) | Standardize JSON: `{ "error": "...", "code": 400 }` |
+
+---
+
+## 10. Potential Future Features
+
+| Feature | Value | Complexity |
+|---------|-------|------------|
+| Streaming `WatchState` RPC | Real-time cart updates for clients | Medium |
+| Event sourcing / audit log | Replay, analytics, debugging | High |
+| Promotion / coupon engine plugin | Business extensibility | Medium |
+| Partial cart reservation / inventory lock | Stock accuracy under concurrency | High |
+| Multi-currency pricing | Globalization | Medium |
+| GraphQL facade | Client flexibility | Medium |
+
+---
+
+## 11. Suggested Prioritized Backlog (Condensed)
+
+1. Coverage test + decode error mapping (P0)
+2. Proto regeneration & cleanup (P0)
+3. Metrics wrapper for registry (P1)
+4. Multi-node ownership integration test (P1)
+5. Delivery pricing abstraction (P2)
+6. Lease version in remote RPCs (P2)
+7. BatchMutate evaluation (P3)
+8. TLS / auth hardening (P3) if going multi-tenant/public
+9. Event sourcing (Evaluate after stability) (P4)
+
+---
+
+## 12. Simplifying the Developer Workflow
+
+| Pain | Simplifier |
+|------|------------|
+| Manual mutation boilerplate | Code generator for registry stubs |
+| Forgetting totals | Enforce WithTotals lint: fail if mutation touches items/deliveries without flag |
+| Hard to inspect remote ownership | `/internal/ownership` debug endpoint (JSON of local + remoteIndex) |
+| Hard to see mutation timings | Add `?debug=latency` header to return per-mutation durations |
+| Cookie dev confusion (Secure flag) | Env var: `DEV_INSECURE_COOKIES=1` |
+
+---
+
+## 13. Example: Mutation Codegen Sketch (Future)
+
+Input: cart_actor.proto  
+Output: `mutation_auto.go`
+- Detect messages used in RPC wrappers (e.g., `AddItemRequest` → payload field).
+- Generate `RegisterMutation` template if handler not found.
+- Mark with `// TODO implement logic`.
+
+---
+
+## 14. Risk / Impact Matrix (Abbreviated)
+
+| Change | Risk | Mitigation |
+|--------|------|-----------|
+| Replace remote switch with registry | Possible missing registration → runtime error | Coverage test gating CI |
+| Lease introduction | Split-brain if version mishandled | Increment + assert monotonic; test race |
+| BatchMutate | Large atomic operations starving others | Size limits & fair scheduling |
+| Event sourcing | Storage + replay complexity | Start with append-only log + compaction job |
+
+---
+
+## 15. Contributing Workflow (Proposed)
+
+1. Add / modify proto → run `make protogen`
+2. Implement mutation logic → add `RegisterMutation` invocation
+3. Add/Update tests (unit + integration)
+4. Run `make verify` (lint, test, coverage, proto diff)
+5. Open PR (template auto-checklist referencing this TODO)
+6. Merge requires green CI + coverage threshold
+
+---
+
+## 16. Open Questions
+
+| Question | Notes |
+|----------|-------|
+| Do we need sticky sessions for HTTP layer scaling? | Currently cart id routing suffices |
+| Should deliveries prune invalid line references on SetCartRequest? | Inconsistency risk; add optional cleanup |
+| Is checkout idempotency strict enough? | Multiple create vs update semantics |
+| Add version field to CartState for optimistic concurrency? | Could enable external CAS writes |
+
+---
+
+## 17. Tracking
+
+Mark any completed tasks with `[x]`:
+
+- [ ] Coverage test
+- [ ] Decode helper + 400 mapping
+- [ ] Proto cleanup
+- [ ] Registry metrics instrumentation
+- [ ] Ownership multi-node test
+- [ ] Lease versioning
+- [ ] Delivery pricing abstraction
+- [ ] TLS/mTLS internal
+- [ ] BatchMutate design doc
+
+---
+
+_Last updated: roadmap draft – refine after first metrics & scaling test run._

amqp-order-handler.go

@@ -1,83 +0,0 @@
-package main
-
-import (
-	"log"
-
-	amqp "github.com/rabbitmq/amqp091-go"
-)
-
-type AmqpOrderHandler struct {
-	Url        string
-	connection *amqp.Connection
-	//channel    *amqp.Channel
-}
-
-const (
-	topic = "order-placed"
-)
-
-func (t *AmqpOrderHandler) Connect() error {
-
-	conn, err := amqp.DialConfig(t.Url, amqp.Config{
-		//Vhost:      "/",
-		Properties: amqp.NewConnectionProperties(),
-	})
-
-	if err != nil {
-		return err
-	}
-	t.connection = conn
-	ch, err := conn.Channel()
-	if err != nil {
-		return err
-	}
-	defer ch.Close()
-	if err := ch.ExchangeDeclare(
-		topic,   // name
-		"topic", // type
-		true,    // durable
-		false,   // auto-delete
-		false,   // internal
-		false,   // noWait
-		nil,     // arguments
-	); err != nil {
-		return err
-	}
-
-	if _, err = ch.QueueDeclare(
-		topic, // name of the queue
-		true,  // durable
-		false, // delete when unused
-		false, // exclusive
-		false, // noWait
-		nil,   // arguments
-	); err != nil {
-		return err
-	}
-
-	return nil
-}
-
-func (t *AmqpOrderHandler) Close() error {
-	log.Println("Closing master channel")
-	return t.connection.Close()
-	//return t.channel.Close()
-}
-
-func (t *AmqpOrderHandler) OrderCompleted(data []byte) error {
-	ch, err := t.connection.Channel()
-	if err != nil {
-		return err
-	}
-	defer ch.Close()
-	return ch.Publish(
-		topic,
-		topic,
-		true,
-		false,
-		amqp.Publishing{
-			ContentType: "application/json",
-			Body:        data,
-		},
-	)
-}

cart-grain.go

@@ -1,608 +0,0 @@
-package main
-
-import (
-	"bytes"
-	"encoding/json"
-	"fmt"
-	"log"
-	"slices"
-	"sync"
-	"time"
-
-	messages "git.tornberg.me/go-cart-actor/proto"
-)
-
-type CartId [16]byte
-
-func (id CartId) MarshalJSON() ([]byte, error) {
-	return json.Marshal(id.String())
-}
-
-func (id *CartId) UnmarshalJSON(data []byte) error {
-	var str string
-	err := json.Unmarshal(data, &str)
-	if err != nil {
-		return err
-	}
-	copy(id[:], []byte(str))
-	return nil
-}
-
-type StockStatus int
-
-const (
-	OutOfStock StockStatus = 0
-	LowStock   StockStatus = 1
-	InStock    StockStatus = 2
-)
-
-type CartItem struct {
-	Id          int         `json:"id"`
-	ItemId      int         `json:"itemId,omitempty"`
-	ParentId    int         `json:"parentId,omitempty"`
-	Sku         string      `json:"sku"`
-	Name        string      `json:"name"`
-	Price       int64       `json:"price"`
-	TotalPrice  int64       `json:"totalPrice"`
-	TotalTax    int64       `json:"totalTax"`
-	OrgPrice    int64       `json:"orgPrice"`
-	Stock       StockStatus `json:"stock"`
-	Quantity    int         `json:"qty"`
-	Tax         int         `json:"tax"`
-	TaxRate     int         `json:"taxRate"`
-	Brand       string      `json:"brand,omitempty"`
-	Category    string      `json:"category,omitempty"`
-	Category2   string      `json:"category2,omitempty"`
-	Category3   string      `json:"category3,omitempty"`
-	Category4   string      `json:"category4,omitempty"`
-	Category5   string      `json:"category5,omitempty"`
-	Disclaimer  string      `json:"disclaimer,omitempty"`
-	SellerId    string      `json:"sellerId,omitempty"`
-	SellerName  string      `json:"sellerName,omitempty"`
-	ArticleType string      `json:"type,omitempty"`
-	Image       string      `json:"image,omitempty"`
-	Outlet      *string     `json:"outlet,omitempty"`
-	StoreId     *string     `json:"storeId,omitempty"`
-}
-
-type CartDelivery struct {
-	Id          int                   `json:"id"`
-	Provider    string                `json:"provider"`
-	Price       int64                 `json:"price"`
-	Items       []int                 `json:"items"`
-	PickupPoint *messages.PickupPoint `json:"pickupPoint,omitempty"`
-}
-
-type CartGrain struct {
-	mu                sync.RWMutex
-	lastItemId        int
-	lastDeliveryId    int
-	storageMessages   []Message
-	Id                CartId          `json:"id"`
-	Items             []*CartItem     `json:"items"`
-	TotalPrice        int64           `json:"totalPrice"`
-	TotalTax          int64           `json:"totalTax"`
-	TotalDiscount     int64           `json:"totalDiscount"`
-	Deliveries        []*CartDelivery `json:"deliveries,omitempty"`
-	Processing        bool            `json:"processing"`
-	PaymentInProgress bool            `json:"paymentInProgress"`
-	OrderReference    string          `json:"orderReference,omitempty"`
-	PaymentStatus     string          `json:"paymentStatus,omitempty"`
-}
-
-type Grain interface {
-	GetId() CartId
-	HandleMessage(message *Message, isReplay bool) (*FrameWithPayload, error)
-	GetCurrentState() (*FrameWithPayload, error)
-}
-
-func (c *CartGrain) GetId() CartId {
-	return c.Id
-}
-
-func (c *CartGrain) GetLastChange() int64 {
-	if len(c.storageMessages) == 0 {
-		return 0
-	}
-	return *c.storageMessages[len(c.storageMessages)-1].TimeStamp
-}
-
-func (c *CartGrain) GetCurrentState() (*FrameWithPayload, error) {
-	result, err := json.Marshal(c)
-	if err != nil {
-		ret := MakeFrameWithPayload(0, 400, []byte(err.Error()))
-		return &ret, nil
-	}
-	ret := MakeFrameWithPayload(0, 200, result)
-	return &ret, nil
-}
-
-func getInt(data interface{}) (int, error) {
-	switch v := data.(type) {
-	case float64:
-		return int(v), nil
-	case int:
-		return v, nil
-	default:
-		return 0, fmt.Errorf("invalid type")
-	}
-}
-
-func getItemData(sku string, qty int, country string) (*messages.AddItem, error) {
-	item, err := FetchItem(sku, country)
-	if err != nil {
-		return nil, err
-	}
-	orgPrice, _ := getInt(item.Fields[5])
-
-	price, priceErr := getInt(item.Fields[4])
-
-	if priceErr != nil {
-		return nil, fmt.Errorf("invalid price")
-	}
-
-	stock := InStock
-	if item.StockLevel == "0" || item.StockLevel == "" {
-		stock = OutOfStock
-	} else if item.StockLevel == "5+" {
-		stock = LowStock
-	}
-	articleType, _ := item.Fields[1].(string)
-	outletGrade, ok := item.Fields[20].(string)
-	var outlet *string
-	if ok {
-		outlet = &outletGrade
-	}
-	sellerId, _ := item.Fields[24].(string)
-	sellerName, _ := item.Fields[9].(string)
-
-	brand, _ := item.Fields[2].(string)
-	category, _ := item.Fields[10].(string)
-	category2, _ := item.Fields[11].(string)
-	category3, _ := item.Fields[12].(string)
-	category4, _ := item.Fields[13].(string)
-	category5, _ := item.Fields[14].(string)
-
-	return &messages.AddItem{
-		ItemId:      int64(item.Id),
-		Quantity:    int32(qty),
-		Price:       int64(price),
-		OrgPrice:    int64(orgPrice),
-		Sku:         sku,
-		Name:        item.Title,
-		Image:       item.Img,
-		Stock:       int32(stock),
-		Brand:       brand,
-		Category:    category,
-		Category2:   category2,
-		Category3:   category3,
-		Category4:   category4,
-		Category5:   category5,
-		Tax:         2500,
-		SellerId:    sellerId,
-		SellerName:  sellerName,
-		ArticleType: articleType,
-		Disclaimer:  item.Disclaimer,
-		Country:     country,
-		Outlet:      outlet,
-	}, nil
-}
-
-func (c *CartGrain) AddItem(sku string, qty int, country string, storeId *string) (*FrameWithPayload, error) {
-	cartItem, err := getItemData(sku, qty, country)
-	if err != nil {
-		return nil, err
-	}
-	cartItem.StoreId = storeId
-	return c.HandleMessage(&Message{
-		Type:    2,
-		Content: cartItem,
-	}, false)
-}
-
-func (c *CartGrain) GetStorageMessage(since int64) []StorableMessage {
-	c.mu.RLock()
-	defer c.mu.RUnlock()
-	ret := make([]StorableMessage, 0)
-
-	for _, message := range c.storageMessages {
-		if *message.TimeStamp > since {
-			ret = append(ret, message)
-		}
-	}
-	return ret
-}
-
-func (c *CartGrain) GetState() ([]byte, error) {
-	return json.Marshal(c)
-}
-
-func (c *CartGrain) ItemsWithDelivery() []int {
-	ret := make([]int, 0, len(c.Items))
-	for _, item := range c.Items {
-		for _, delivery := range c.Deliveries {
-			for _, id := range delivery.Items {
-				if item.Id == id {
-					ret = append(ret, id)
-				}
-			}
-		}
-	}
-	return ret
-}
-
-func (c *CartGrain) ItemsWithoutDelivery() []int {
-	ret := make([]int, 0, len(c.Items))
-	hasDelivery := c.ItemsWithDelivery()
-	for _, item := range c.Items {
-		found := false
-		for _, id := range hasDelivery {
-			if item.Id == id {
-				found = true
-				break
-			}
-		}
-
-		if !found {
-			ret = append(ret, item.Id)
-		}
-	}
-	return ret
-}
-
-func (c *CartGrain) FindItemWithSku(sku string) (*CartItem, bool) {
-	c.mu.RLock()
-	defer c.mu.RUnlock()
-	for _, item := range c.Items {
-		if item.Sku == sku {
-			return item, true
-		}
-	}
-	return nil, false
-}
-
-func GetTaxAmount(total int64, tax int) int64 {
-	taxD := 10000 / float64(tax)
-	return int64(float64(total) / float64((1 + taxD)))
-}
-
-func (c *CartGrain) HandleMessage(message *Message, isReplay bool) (*FrameWithPayload, error) {
-	if message.TimeStamp == nil {
-		now := time.Now().Unix()
-		message.TimeStamp = &now
-	}
-	grainMutations.Inc()
-	var err error
-	switch message.Type {
-	case SetCartItemsType:
-		msg, ok := message.Content.(*messages.SetCartRequest)
-		if !ok {
-			err = fmt.Errorf("expected SetCartItems")
-		} else {
-
-			c.mu.Lock()
-			c.Items = make([]*CartItem, 0, len(msg.Items))
-			c.mu.Unlock()
-			for _, item := range msg.Items {
-				c.AddItem(item.Sku, int(item.Quantity), item.Country, item.StoreId)
-			}
-
-		}
-	case AddRequestType:
-		msg, ok := message.Content.(*messages.AddRequest)
-		if !ok {
-			err = fmt.Errorf("expected AddRequest")
-		} else {
-
-			existingItem, found := c.FindItemWithSku(msg.Sku)
-			if found {
-				existingItem.Quantity += int(msg.Quantity)
-				c.UpdateTotals()
-			} else {
-				return c.AddItem(msg.Sku, int(msg.Quantity), msg.Country, msg.StoreId)
-			}
-
-		}
-	case AddItemType:
-		msg, ok := message.Content.(*messages.AddItem)
-		if !ok {
-			err = fmt.Errorf("expected AddItem")
-		} else {
-
-			if msg.Quantity < 1 {
-				return nil, fmt.Errorf("invalid quantity")
-			}
-			existingItem, found := c.FindItemWithSku(msg.Sku)
-			if found {
-				existingItem.Quantity += int(msg.Quantity)
-				c.UpdateTotals()
-			} else {
-				c.mu.Lock()
-				c.lastItemId++
-				tax := 2500
-				if msg.Tax > 0 {
-					tax = int(msg.Tax)
-				}
-
-				taxAmount := GetTaxAmount(msg.Price, tax)
-
-				c.Items = append(c.Items, &CartItem{
-					Id:          c.lastItemId,
-					ItemId:      int(msg.ItemId),
-					Quantity:    int(msg.Quantity),
-					Sku:         msg.Sku,
-					Name:        msg.Name,
-					Price:       msg.Price,
-					TotalPrice:  msg.Price * int64(msg.Quantity),
-					TotalTax:    int64(taxAmount * int64(msg.Quantity)),
-					Image:       msg.Image,
-					Stock:       StockStatus(msg.Stock),
-					Disclaimer:  msg.Disclaimer,
-					Brand:       msg.Brand,
-					Category:    msg.Category,
-					Category2:   msg.Category2,
-					Category3:   msg.Category3,
-					Category4:   msg.Category4,
-					Category5:   msg.Category5,
-					OrgPrice:    msg.OrgPrice,
-					ArticleType: msg.ArticleType,
-					Outlet:      msg.Outlet,
-					SellerId:    msg.SellerId,
-					SellerName:  msg.SellerName,
-					Tax:         int(taxAmount),
-					TaxRate:     tax,
-					StoreId:     msg.StoreId,
-				})
-				c.UpdateTotals()
-				c.mu.Unlock()
-			}
-
-		}
-	case ChangeQuantityType:
-		msg, ok := message.Content.(*messages.ChangeQuantity)
-		if !ok {
-			err = fmt.Errorf("expected ChangeQuantity")
-		} else {
-
-			for i, item := range c.Items {
-				if item.Id == int(msg.Id) {
-					if msg.Quantity <= 0 {
-						//c.TotalPrice -= item.Price * int64(item.Quantity)
-						c.Items = append(c.Items[:i], c.Items[i+1:]...)
-					} else {
-						//diff := int(msg.Quantity) - item.Quantity
-						item.Quantity = int(msg.Quantity)
-						//c.TotalPrice += item.Price * int64(diff)
-					}
-
-					break
-				}
-			}
-			c.UpdateTotals()
-
-		}
-	case RemoveItemType:
-		msg, ok := message.Content.(*messages.RemoveItem)
-		if !ok {
-			err = fmt.Errorf("expected RemoveItem")
-		} else {
-
-			items := make([]*CartItem, 0, len(c.Items))
-			for _, item := range c.Items {
-				if item.Id == int(msg.Id) {
-					//c.TotalPrice -= item.Price * int64(item.Quantity)
-				} else {
-					items = append(items, item)
-				}
-			}
-			c.Items = items
-			c.UpdateTotals()
-		}
-	case SetDeliveryType:
-		msg, ok := message.Content.(*messages.SetDelivery)
-		if !ok {
-			err = fmt.Errorf("expected SetDelivery")
-		} else {
-
-			c.lastDeliveryId++
-			items := make([]int, 0)
-			withDelivery := c.ItemsWithDelivery()
-			if len(msg.Items) == 0 {
-				items = append(items, c.ItemsWithoutDelivery()...)
-			} else {
-				for _, id := range msg.Items {
-					for _, item := range c.Items {
-						if item.Id == int(id) {
-							if slices.Contains(withDelivery, item.Id) {
-								return nil, fmt.Errorf("item already has delivery")
-							}
-							items = append(items, int(item.Id))
-							break
-						}
-					}
-				}
-			}
-			if len(items) > 0 {
-				c.Deliveries = append(c.Deliveries, &CartDelivery{
-					Id:          c.lastDeliveryId,
-					Provider:    msg.Provider,
-					PickupPoint: msg.PickupPoint,
-					Price:       4900,
-					Items:       items,
-				})
-
-				c.UpdateTotals()
-
-			}
-
-		}
-	case RemoveDeliveryType:
-		msg, ok := message.Content.(*messages.RemoveDelivery)
-		if !ok {
-			err = fmt.Errorf("expected RemoveDelivery")
-		} else {
-
-			deliveries := make([]*CartDelivery, 0, len(c.Deliveries))
-			for _, delivery := range c.Deliveries {
-				if delivery.Id == int(msg.Id) {
-					c.TotalPrice -= delivery.Price
-				} else {
-					deliveries = append(deliveries, delivery)
-				}
-			}
-			c.Deliveries = deliveries
-			c.UpdateTotals()
-		}
-	case SetPickupPointType:
-		msg, ok := message.Content.(*messages.SetPickupPoint)
-		if !ok {
-			err = fmt.Errorf("expected SetPickupPoint")
-		} else {
-
-			for _, delivery := range c.Deliveries {
-				if delivery.Id == int(msg.DeliveryId) {
-					delivery.PickupPoint = &messages.PickupPoint{
-						Id:      msg.Id,
-						Address: msg.Address,
-						City:    msg.City,
-						Zip:     msg.Zip,
-						Country: msg.Country,
-						Name:    msg.Name,
-					}
-					break
-				}
-			}
-
-		}
-	case CreateCheckoutOrderType:
-		msg, ok := message.Content.(*messages.CreateCheckoutOrder)
-		if !ok {
-			err = fmt.Errorf("expected CreateCheckoutOrder")
-		} else {
-
-			orderLines := make([]*Line, 0, len(c.Items))
-
-			c.PaymentInProgress = true
-			c.Processing = true
-			for _, item := range c.Items {
-
-				orderLines = append(orderLines, &Line{
-					Type:           "physical",
-					Reference:      item.Sku,
-					Name:           item.Name,
-					Quantity:       item.Quantity,
-					UnitPrice:      int(item.Price),
-					TaxRate:        2500, // item.TaxRate,
-					QuantityUnit:   "st",
-					TotalAmount:    int(item.TotalPrice),
-					TotalTaxAmount: int(item.TotalTax),
-					ImageURL:       fmt.Sprintf("https://www.elgiganten.se%s", item.Image),
-				})
-			}
-			for _, line := range c.Deliveries {
-				if line.Price > 0 {
-					orderLines = append(orderLines, &Line{
-						Type:           "shipping_fee",
-						Reference:      line.Provider,
-						Name:           "Delivery",
-						Quantity:       1,
-						UnitPrice:      int(line.Price),
-						TaxRate:        2500, // item.TaxRate,
-						QuantityUnit:   "st",
-						TotalAmount:    int(line.Price),
-						TotalTaxAmount: int(GetTaxAmount(line.Price, 2500)),
-					})
-				}
-			}
-			order := CheckoutOrder{
-				PurchaseCountry:    "SE",
-				PurchaseCurrency:   "SEK",
-				Locale:             "sv-se",
-				OrderAmount:        int(c.TotalPrice),
-				OrderTaxAmount:     int(c.TotalTax),
-				OrderLines:         orderLines,
-				MerchantReference1: c.Id.String(),
-				MerchantURLS: &CheckoutMerchantURLS{
-					Terms:        msg.Terms,
-					Checkout:     msg.Checkout,
-					Confirmation: msg.Confirmation,
-					Validation:   msg.Validation,
-					Push:         msg.Push,
-				},
-			}
-			orderPayload, err := json.Marshal(order)
-			if err != nil {
-				return nil, err
-			}
-			var klarnaOrder *CheckoutOrder
-			if c.OrderReference != "" {
-				log.Printf("Updating order id %s", c.OrderReference)
-				klarnaOrder, err = KlarnaInstance.UpdateOrder(c.OrderReference, bytes.NewReader(orderPayload))
-			} else {
-				klarnaOrder, err = KlarnaInstance.CreateOrder(bytes.NewReader(orderPayload))
-			}
-			// log.Printf("Order result: %+v", klarnaOrder)
-			if nil != err {
-				log.Printf("error from klarna: %v", err)
-				return nil, err
-			}
-			if c.OrderReference == "" {
-				c.OrderReference = klarnaOrder.ID
-				c.PaymentStatus = klarnaOrder.Status
-			}
-
-			orderData, err := json.Marshal(klarnaOrder)
-			if nil != err {
-				return nil, err
-			}
-
-			result := MakeFrameWithPayload(RemoteCreateOrderReply, 200, orderData)
-			return &result, nil
-		}
-	case OrderCompletedType:
-		msg, ok := message.Content.(*messages.OrderCreated)
-		if !ok {
-			log.Printf("expected OrderCompleted, got %T", message.Content)
-			err = fmt.Errorf("expected OrderCompleted")
-		} else {
-			c.OrderReference = msg.OrderId
-			c.PaymentStatus = msg.Status
-			c.PaymentInProgress = false
-		}
-	default:
-		err = fmt.Errorf("unknown message type %d", message.Type)
-	}
-	if err != nil {
-		return nil, err
-	}
-
-	if !isReplay {
-		c.mu.Lock()
-		c.storageMessages = append(c.storageMessages, *message)
-		c.mu.Unlock()
-	}
-	result, err := json.Marshal(c)
-	msg := MakeFrameWithPayload(RemoteHandleMutationReply, 200, result)
-	return &msg, err
-}
-
-func (c *CartGrain) UpdateTotals() {
-	c.TotalPrice = 0
-	c.TotalTax = 0
-	c.TotalDiscount = 0
-	for _, item := range c.Items {
-		rowTotal := item.Price * int64(item.Quantity)
-		rowTax := int64(item.Tax) * int64(item.Quantity)
-		item.TotalPrice = rowTotal
-		item.TotalTax = rowTax
-		c.TotalPrice += rowTotal
-		c.TotalTax += rowTax
-		itemDiff := max(0, item.OrgPrice-item.Price)
-		c.TotalDiscount += itemDiff * int64(item.Quantity)
-	}
-	for _, delivery := range c.Deliveries {
-		c.TotalPrice += delivery.Price
-		c.TotalTax += GetTaxAmount(delivery.Price, 2500)
-	}
-
-}

cart-grain_test.go

@@ -1,248 +0,0 @@
-package main
-
-import (
-	"testing"
-	"time"
-
-	messages "git.tornberg.me/go-cart-actor/proto"
-)
-
-func GetMessage(t uint16, data interface{}) *Message {
-	ts := time.Now().Unix()
-	return &Message{
-		TimeStamp: &ts,
-		Type:      t,
-		Content:   data,
-	}
-}
-
-func TestTaxAmount(t *testing.T) {
-	taxAmount := GetTaxAmount(12500, 2500)
-	if taxAmount != 2500 {
-		t.Errorf("Expected 2500, got %d\n", taxAmount)
-	}
-}
-
-func TestAddToCartShortCut(t *testing.T) {
-	grain, err := spawn(ToCartId("kalle"))
-	if err != nil {
-		t.Errorf("Error spawning: %v\n", err)
-	}
-	if len(grain.Items) != 0 {
-		t.Errorf("Expected 0 items, got %d\n", len(grain.Items))
-	}
-	msg := GetMessage(AddItemType, &messages.AddItem{
-		Quantity: 2,
-		Price:    100,
-		Sku:      "123",
-		Name:     "Test item",
-		Image:    "test.jpg",
-	})
-
-	_, err = grain.HandleMessage(msg, false)
-	if err != nil {
-		t.Errorf("Error handling message: %v\n", err)
-	}
-	if len(grain.Items) != 1 {
-		t.Errorf("Expected 1 item, got %d\n", len(grain.Items))
-	}
-	if grain.Items[0].Quantity != 2 {
-		t.Errorf("Expected quantity 2, got %d\n", grain.Items[0].Quantity)
-	}
-	if len(grain.storageMessages) != 1 {
-		t.Errorf("Expected 1 storage message, got %d\n", len(grain.storageMessages))
-	}
-	shortCutMessage := GetMessage(AddRequestType, &messages.AddRequest{
-		Quantity: 2,
-		Sku:      "123",
-	})
-	_, err = grain.HandleMessage(shortCutMessage, false)
-	if err != nil {
-		t.Errorf("Error handling message: %v\n", err)
-	}
-	if len(grain.Items) != 1 {
-		t.Errorf("Expected 1 item, got %d\n", len(grain.Items))
-	}
-	if len(grain.storageMessages) != 2 {
-		t.Errorf("Expected 2 storage message, got %d\n", len(grain.storageMessages))
-	}
-	if grain.storageMessages[0].Type != AddItemType {
-		t.Errorf("Expected AddItemType, got %d\n", grain.storageMessages[0].Type)
-	}
-	if grain.storageMessages[1].Type != AddRequestType {
-		t.Errorf("Expected AddRequestType, got %d\n", grain.storageMessages[1].Type)
-	}
-}
-
-func TestAddRequestToGrain(t *testing.T) {
-	grain, err := spawn(ToCartId("kalle"))
-	if err != nil {
-		t.Errorf("Error spawning: %v\n", err)
-	}
-	msg := GetMessage(AddRequestType, &messages.AddRequest{
-		Quantity: 2,
-		Sku:      "763281",
-	})
-	result, err := grain.HandleMessage(msg, false)
-	if err != nil {
-		t.Errorf("Error handling message: %v\n", err)
-	}
-	if result.StatusCode != 200 {
-		t.Errorf("Call failed\n")
-	}
-	t.Log(result)
-}
-
-func TestAddToCart(t *testing.T) {
-	grain, err := spawn(ToCartId("kalle"))
-	if err != nil {
-		t.Errorf("Error spawning: %v\n", err)
-	}
-	if len(grain.Items) != 0 {
-		t.Errorf("Expected 0 items, got %d\n", len(grain.Items))
-	}
-	msg := GetMessage(AddItemType, &messages.AddItem{
-		Quantity: 2,
-		Price:    100,
-		Sku:      "123",
-		Name:     "Test item",
-		Image:    "test.jpg",
-	})
-
-	result, err := grain.HandleMessage(msg, false)
-
-	if err != nil {
-		t.Errorf("Error handling message: %v\n", err)
-	}
-	if result.StatusCode != 200 {
-		t.Errorf("Call failed\n")
-	}
-	if grain.TotalPrice != 200 {
-		t.Errorf("Expected total price 200, got %d\n", grain.TotalPrice)
-	}
-	if len(grain.Items) != 1 {
-		t.Errorf("Expected 1 item, got %d\n", len(grain.Items))
-	}
-	if grain.Items[0].Quantity != 2 {
-		t.Errorf("Expected quantity 2, got %d\n", grain.Items[0].Quantity)
-	}
-	result, err = grain.HandleMessage(msg, false)
-	if err != nil {
-		t.Errorf("Error handling message: %v\n", err)
-	}
-	if result.StatusCode != 200 {
-		t.Errorf("Call failed\n")
-	}
-	if grain.Items[0].Quantity != 4 {
-		t.Errorf("Expected quantity 4, got %d\n", grain.Items[0].Quantity)
-	}
-	if grain.TotalPrice != 400 {
-		t.Errorf("Expected total price 400, got %d\n", grain.TotalPrice)
-	}
-}
-
-func TestSetDelivery(t *testing.T) {
-	grain, err := spawn(ToCartId("kalle"))
-	if err != nil {
-		t.Errorf("Error spawning: %v\n", err)
-	}
-	if len(grain.Items) != 0 {
-		t.Errorf("Expected 0 items, got %d\n", len(grain.Items))
-	}
-	msg := GetMessage(AddItemType, &messages.AddItem{
-		Quantity: 2,
-		Price:    100,
-		Sku:      "123",
-		Name:     "Test item",
-		Image:    "test.jpg",
-	})
-
-	grain.HandleMessage(msg, false)
-
-	msg = GetMessage(AddItemType, &messages.AddItem{
-		Quantity: 2,
-		Price:    100,
-		Sku:      "123",
-		Name:     "Test item",
-		Image:    "test.jpg",
-	})
-
-	result, err := grain.HandleMessage(msg, false)
-
-	if err != nil {
-		t.Errorf("Error handling message: %v\n", err)
-	}
-	if result.StatusCode != 200 {
-		t.Errorf("Call failed\n")
-	}
-
-	setDelivery := GetMessage(SetDeliveryType, &messages.SetDelivery{
-		Provider: "test",
-		Items:    []int64{1},
-	})
-
-	_, err = grain.HandleMessage(setDelivery, false)
-	if err != nil {
-		t.Errorf("Error handling message: %v\n", err)
-	}
-	if len(grain.Deliveries) != 1 {
-		t.Errorf("Expected 1 delivery, got %d\n", len(grain.Deliveries))
-	}
-	if len(grain.Deliveries[0].Items) != 1 {
-		t.Errorf("Expected 1 items in delivery, got %d\n", len(grain.Deliveries[0].Items))
-	}
-}
-
-func TestSetDeliveryOnAll(t *testing.T) {
-	grain, err := spawn(ToCartId("kalle"))
-	if err != nil {
-		t.Errorf("Error spawning: %v\n", err)
-	}
-	if len(grain.Items) != 0 {
-		t.Errorf("Expected 0 items, got %d\n", len(grain.Items))
-	}
-	msg := GetMessage(AddItemType, &messages.AddItem{
-		Quantity: 2,
-		Price:    100,
-		Sku:      "123",
-		Name:     "Test item",
-		Image:    "test.jpg",
-	})
-
-	grain.HandleMessage(msg, false)
-
-	msg = GetMessage(AddItemType, &messages.AddItem{
-		Quantity: 2,
-		Price:    100,
-		Sku:      "1233",
-		Name:     "Test item2",
-		Image:    "test.jpg",
-	})
-
-	result, err := grain.HandleMessage(msg, false)
-
-	if err != nil {
-		t.Errorf("Error handling message: %v\n", err)
-	}
-	if result.StatusCode != 200 {
-		t.Errorf("Call failed\n")
-	}
-
-	setDelivery := GetMessage(SetDeliveryType, &messages.SetDelivery{
-		Provider: "test",
-		Items:    []int64{},
-	})
-
-	_, err = grain.HandleMessage(setDelivery, false)
-	if err != nil {
-		t.Errorf("Error handling message: %v\n", err)
-	}
-	if len(grain.Deliveries) != 1 {
-		t.Errorf("Expected 1 delivery, got %d\n", len(grain.Deliveries))
-	}
-
-	if len(grain.Deliveries[0].Items) != 2 {
-		t.Errorf("Expected 2 items in delivery, got %d\n", len(grain.Deliveries[0].Items))
-	}
-
-}

cmd/backoffice/fileserver.go

@@ -0,0 +1,280 @@
+package main
+
+import (
+	"bufio"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"io/fs"
+	"net/http"
+	"os"
+	"path/filepath"
+	"sort"
+	"strconv"
+	"strings"
+	"time"
+
+	"git.tornberg.me/go-cart-actor/pkg/actor"
+	"git.tornberg.me/go-cart-actor/pkg/cart"
+)
+
+type FileServer struct {
+	// Define fields here
+	dataDir string
+	storage actor.LogStorage[cart.CartGrain]
+}
+
+func NewFileServer(dataDir string, storage actor.LogStorage[cart.CartGrain]) *FileServer {
+	return &FileServer{
+		dataDir: dataDir,
+		storage: storage,
+	}
+}
+
+func isValidId(id string) (uint64, bool) {
+	if nr, err := strconv.ParseUint(id, 10, 64); err == nil {
+		return nr, true
+	}
+	if nr, ok := cart.ParseCartId(id); ok {
+		return uint64(nr), true
+	}
+	return 0, false
+}
+
+func isValidFileId(name string) (uint64, bool) {
+
+	parts := strings.Split(name, ".")
+	if len(parts) > 1 && parts[1] == "events" {
+		idStr := parts[0]
+
+		return isValidId(idStr)
+	}
+	return 0, false
+}
+
+// func AccessTime(info os.FileInfo) (time.Time, bool) {
+// 	switch stat := info.Sys().(type) {
+// 	case *syscall.Stat_t:
+// 		// Linux: Atim; macOS/BSD: Atimespec
+// 		// Use reflection or build tags if naming differs.
+// 		// Linux:
+// 		if stat.Atim.Sec != 0 || stat.Atim.Nsec != 0 {
+// 			return time.Unix(int64(stat.Atim.Sec), int64(stat.Atim.Nsec)), true
+// 		}
+// 		// macOS/BSD example (uncomment if needed):
+// 		//return time.Unix(int64(stat.Atimespec.Sec), int64(stat.Atimespec.Nsec)), true
+// 	}
+// 	return time.Time{}, false
+// }
+
+func appendFileInfo(info fs.FileInfo, out *CartFileInfo) *CartFileInfo {
+	//sys := info.Sys()
+	//fmt.Printf("sys type %T", sys)
+	out.Size = info.Size()
+	out.Modified = info.ModTime()
+	//out.Accessed, _ = AccessTime(info)
+	return out
+}
+
+// var cartFileRe = regexp.MustCompile(`^(\d+)\.events\.log$`)
+
+func listCartFiles(dir string) ([]*CartFileInfo, error) {
+	entries, err := os.ReadDir(dir)
+	if err != nil {
+		if errors.Is(err, os.ErrNotExist) {
+			return []*CartFileInfo{}, nil
+		}
+		return nil, err
+	}
+	out := make([]*CartFileInfo, 0)
+	for _, e := range entries {
+		if e.IsDir() {
+			continue
+		}
+		id, valid := isValidFileId(e.Name())
+		if !valid {
+			continue
+		}
+
+		info, err := e.Info()
+		if err != nil {
+			continue
+		}
+		info.Sys()
+		out = append(out, appendFileInfo(info, &CartFileInfo{
+			ID:     fmt.Sprintf("%d", id),
+			CartId: cart.CartId(id),
+		}))
+	}
+	return out, nil
+}
+
+func readRawLogLines(path string) ([]json.RawMessage, error) {
+	fh, err := os.Open(path)
+	if err != nil {
+		return nil, err
+	}
+	defer fh.Close()
+	lines := make([]json.RawMessage, 0, 64)
+	s := bufio.NewScanner(fh)
+	// increase buffer to handle larger JSON lines
+	buf := make([]byte, 0, 1024*1024)
+	s.Buffer(buf, 1024*1024)
+	for s.Scan() {
+		line := s.Bytes()
+		if line == nil {
+			continue
+		}
+		lines = append(lines, line)
+	}
+	if err := s.Err(); err != nil {
+		return nil, err
+	}
+	return lines, nil
+}
+
+func writeJSON(w http.ResponseWriter, status int, v any) {
+	w.Header().Set("Content-Type", "application/json")
+	w.Header().Set("Cache-Control", "no-cache")
+	w.WriteHeader(status)
+	_ = json.NewEncoder(w).Encode(v)
+}
+
+func (fs *FileServer) CartsHandler(w http.ResponseWriter, r *http.Request) {
+	list, err := listCartFiles(fs.dataDir)
+	if err != nil {
+		writeJSON(w, http.StatusInternalServerError, map[string]string{"error": err.Error()})
+		return
+	}
+	// sort by modified desc
+	sort.Slice(list, func(i, j int) bool { return list[i].Modified.After(list[j].Modified) })
+
+	writeJSON(w, http.StatusOK, map[string]any{
+		"count": len(list),
+		"carts": list,
+	})
+}
+
+func (fs *FileServer) PromotionsHandler(w http.ResponseWriter, r *http.Request) {
+	fileName := filepath.Join(fs.dataDir, "promotions.json")
+	if r.Method == http.MethodGet {
+		file, err := os.Open(fileName)
+		if err != nil {
+			writeJSON(w, http.StatusInternalServerError, map[string]string{"error": err.Error()})
+			return
+		}
+		defer file.Close()
+
+		io.Copy(w, file)
+		return
+	}
+	if r.Method == http.MethodPost {
+		file, err := os.Create(fileName)
+		if err != nil {
+			writeJSON(w, http.StatusInternalServerError, map[string]string{"error": err.Error()})
+			return
+		}
+		defer file.Close()
+
+		io.Copy(file, r.Body)
+		return
+	}
+
+	w.WriteHeader(http.StatusMethodNotAllowed)
+}
+
+func (fs *FileServer) VoucherHandler(w http.ResponseWriter, r *http.Request) {
+	fileName := filepath.Join(fs.dataDir, "vouchers.json")
+	if r.Method == http.MethodGet {
+		file, err := os.Open(fileName)
+		if err != nil {
+			writeJSON(w, http.StatusInternalServerError, map[string]string{"error": err.Error()})
+			return
+		}
+		defer file.Close()
+
+		io.Copy(w, file)
+		return
+	}
+	if r.Method == http.MethodPost {
+		file, err := os.Create(fileName)
+		if err != nil {
+			writeJSON(w, http.StatusInternalServerError, map[string]string{"error": err.Error()})
+			return
+		}
+		defer file.Close()
+
+		io.Copy(file, r.Body)
+		return
+	}
+
+	w.WriteHeader(http.StatusMethodNotAllowed)
+}
+
+func (fs *FileServer) PromotionPartHandler(w http.ResponseWriter, r *http.Request) {
+	idStr := r.PathValue("id")
+	if idStr == "" {
+		w.WriteHeader(http.StatusBadRequest)
+		fmt.Fprintf(w, "missing id")
+		return
+	}
+	_, ok := isValidId(idStr)
+	if !ok {
+		w.WriteHeader(http.StatusBadRequest)
+		fmt.Fprintf(w, "invalid id %s", idStr)
+		return
+	}
+	w.WriteHeader(http.StatusNotImplemented)
+}
+
+type JsonError struct {
+	Error string `json:"error"`
+}
+
+func (fs *FileServer) CartHandler(w http.ResponseWriter, r *http.Request) {
+	idStr := r.PathValue("id")
+	if idStr == "" {
+		writeJSON(w, http.StatusBadRequest, JsonError{Error: "missing id"})
+		return
+	}
+	id, ok := isValidId(idStr)
+	if !ok {
+		writeJSON(w, http.StatusBadRequest, JsonError{Error: "invalid id"})
+		return
+	}
+	// reconstruct state from event log if present
+	grain := cart.NewCartGrain(id, time.Now())
+
+	err := fs.storage.LoadEvents(r.Context(), id, grain)
+	if err != nil {
+		writeJSON(w, http.StatusInternalServerError, JsonError{Error: err.Error()})
+		return
+	}
+
+	path := filepath.Join(fs.dataDir, fmt.Sprintf("%d.events.log", id))
+	info, err := os.Stat(path)
+	if err != nil && errors.Is(err, os.ErrNotExist) {
+		writeJSON(w, http.StatusNotFound, JsonError{Error: "cart not found"})
+		return
+	} else if err != nil {
+		writeJSON(w, http.StatusInternalServerError, JsonError{Error: err.Error()})
+		return
+	}
+	lines, err := readRawLogLines(path)
+	if err != nil {
+		writeJSON(w, http.StatusInternalServerError, JsonError{Error: err.Error()})
+		return
+	}
+	writeJSON(w, http.StatusOK, map[string]any{
+		"id":        id,
+		"cartId":    cart.CartId(id).String(),
+		"state":     grain,
+		"mutations": lines,
+		"meta": map[string]any{
+			"size":     info.Size(),
+			"modified": info.ModTime(),
+			"path":     path,
+		},
+	})
+}

cmd/backoffice/fileserver_test.go

@@ -0,0 +1,89 @@
+package main
+
+import (
+	"math/rand"
+	"os"
+	"path/filepath"
+	"testing"
+	"time"
+
+	"git.tornberg.me/go-cart-actor/pkg/cart"
+)
+
+// TestAppendFileInfoRandomProjectFile picks a random existing .go source file in the
+// repository (from a small curated list to keep the test hermetic) and verifies
+// that appendFileInfo populates Size, Modified and System without mutating the
+// identity fields (ID, CartId). The randomness is only to satisfy the requirement
+// of using "a random project file"; the test behavior is deterministic enough for
+// CI because all chosen files are expected to exist.
+func TestAppendFileInfoRandomProjectFile(t *testing.T) {
+	candidates := []string{
+		filepath.FromSlash("../../pkg/cart/cart_id.go"),
+		filepath.FromSlash("../../pkg/actor/grain.go"),
+		filepath.FromSlash("../../cmd/cart/main.go"),
+	}
+	// Pick one at random.
+	rand.Seed(time.Now().UnixNano())
+	path := candidates[rand.Intn(len(candidates))]
+
+	info, err := os.Stat(path)
+	if err != nil {
+		t.Fatalf("stat failed for %s: %v", path, err)
+	}
+
+	// Pre-populate a CartFileInfo with identity fields.
+	origID := "test-id"
+	origCartId := cart.CartId(12345)
+	cf := &CartFileInfo{ID: origID, CartId: origCartId}
+
+	// Call function under test.
+	got := appendFileInfo(info, cf)
+
+	if got != cf {
+		t.Fatalf("appendFileInfo should return the same pointer instance")
+	}
+
+	if cf.ID != origID {
+		t.Fatalf("ID mutated: expected %q got %q", origID, cf.ID)
+	}
+	if cf.CartId != origCartId {
+		t.Fatalf("CartId mutated: expected %v got %v", origCartId, cf.CartId)
+	}
+
+	if cf.Size != info.Size() {
+		t.Fatalf("Size mismatch: expected %d got %d", info.Size(), cf.Size)
+	}
+
+	mod := info.ModTime()
+	// Allow small clock skew / coarse timestamp truncation.
+	if cf.Modified.Before(mod.Add(-2*time.Second)) || cf.Modified.After(mod.Add(2*time.Second)) {
+		t.Fatalf("Modified not within expected range: want ~%v got %v", mod, cf.Modified)
+	}
+
+}
+
+// TestAppendFileInfoTempFile creates a temporary file to ensure Size and Modified
+// are updated for a freshly written file with known content length.
+func TestAppendFileInfoTempFile(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "temp.events.log")
+	content := []byte("hello world\nanother line\n")
+	if err := os.WriteFile(path, content, 0644); err != nil {
+		t.Fatalf("write temp file failed: %v", err)
+	}
+
+	info, err := os.Stat(path)
+	if err != nil {
+		t.Fatalf("stat temp file failed: %v", err)
+	}
+
+	cf := &CartFileInfo{ID: "temp", CartId: cart.CartId(0)}
+	appendFileInfo(info, cf)
+
+	if cf.Size != int64(len(content)) {
+		t.Fatalf("expected Size %d got %d", len(content), cf.Size)
+	}
+	if cf.Modified.IsZero() {
+		t.Fatalf("Modified should be set")
+	}
+}

cmd/backoffice/hub.go

@@ -0,0 +1,248 @@
+package main
+
+import (
+	"bufio"
+	"crypto/sha1"
+	"encoding/base64"
+	"encoding/binary"
+	"io"
+	"net"
+	"net/http"
+	"strings"
+	"time"
+)
+
+// Hub manages websocket clients and broadcasts messages to them.
+type Hub struct {
+	register   chan *Client
+	unregister chan *Client
+	broadcast  chan []byte
+	clients    map[*Client]bool
+}
+
+// Client represents a single websocket client connection.
+type Client struct {
+	hub  *Hub
+	conn net.Conn
+	send chan []byte
+}
+
+// NewHub constructs a new Hub instance.
+func NewHub() *Hub {
+	return &Hub{
+		register:   make(chan *Client),
+		unregister: make(chan *Client),
+		broadcast:  make(chan []byte, 1024),
+		clients:    make(map[*Client]bool),
+	}
+}
+
+// Run starts the hub event loop.
+func (h *Hub) Run() {
+	for {
+		select {
+		case c := <-h.register:
+			h.clients[c] = true
+		case c := <-h.unregister:
+			if _, ok := h.clients[c]; ok {
+				delete(h.clients, c)
+				close(c.send)
+				_ = c.conn.Close()
+			}
+		case msg := <-h.broadcast:
+			for c := range h.clients {
+				select {
+				case c.send <- msg:
+				default:
+					// Client is slow or dead; drop it.
+					delete(h.clients, c)
+					close(c.send)
+					_ = c.conn.Close()
+				}
+			}
+		}
+	}
+}
+
+// computeAccept computes the Sec-WebSocket-Accept header value.
+func computeAccept(key string) string {
+	const magic = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11"
+	h := sha1.New()
+	h.Write([]byte(key + magic))
+	return base64.StdEncoding.EncodeToString(h.Sum(nil))
+}
+
+// ServeWS upgrades the HTTP request to a WebSocket connection and registers a client.
+func (h *Hub) ServeWS(w http.ResponseWriter, r *http.Request) {
+	if !strings.Contains(strings.ToLower(r.Header.Get("Connection")), "upgrade") || strings.ToLower(r.Header.Get("Upgrade")) != "websocket" {
+		http.Error(w, "upgrade required", http.StatusBadRequest)
+		return
+	}
+	key := r.Header.Get("Sec-WebSocket-Key")
+	if key == "" {
+		http.Error(w, "missing Sec-WebSocket-Key", http.StatusBadRequest)
+		return
+	}
+	accept := computeAccept(key)
+
+	hj, ok := w.(http.Hijacker)
+	if !ok {
+		http.Error(w, "websocket not supported", http.StatusInternalServerError)
+		return
+	}
+	conn, buf, err := hj.Hijack()
+	if err != nil {
+		return
+	}
+
+	// Write the upgrade response
+	response := "HTTP/1.1 101 Switching Protocols\r\n" +
+		"Upgrade: websocket\r\n" +
+		"Connection: Upgrade\r\n" +
+		"Sec-WebSocket-Accept: " + accept + "\r\n" +
+		"\r\n"
+	if _, err := buf.WriteString(response); err != nil {
+		_ = conn.Close()
+		return
+	}
+	if err := buf.Flush(); err != nil {
+		_ = conn.Close()
+		return
+	}
+
+	client := &Client{
+		hub:  h,
+		conn: conn,
+		send: make(chan []byte, 256),
+	}
+	h.register <- client
+	go client.writePump()
+	go client.readPump()
+}
+
+// writeWSFrame writes a single WebSocket frame to the writer.
+func writeWSFrame(w io.Writer, opcode byte, payload []byte) error {
+	// FIN set, opcode as provided
+	header := []byte{0x80 | (opcode & 0x0F)}
+	l := len(payload)
+	switch {
+	case l < 126:
+		header = append(header, byte(l))
+	case l <= 65535:
+		ext := make([]byte, 2)
+		binary.BigEndian.PutUint16(ext, uint16(l))
+		header = append(header, 126)
+		header = append(header, ext...)
+	default:
+		ext := make([]byte, 8)
+		binary.BigEndian.PutUint64(ext, uint64(l))
+		header = append(header, 127)
+		header = append(header, ext...)
+	}
+	if _, err := w.Write(header); err != nil {
+		return err
+	}
+	if l > 0 {
+		if _, err := w.Write(payload); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// readPump handles control frames from the client and discards other incoming frames.
+// This server is broadcast-only to clients.
+func (c *Client) readPump() {
+	defer func() {
+		c.hub.unregister <- c
+	}()
+	reader := bufio.NewReader(c.conn)
+	for {
+		// Read first two bytes
+		b1, err := reader.ReadByte()
+		if err != nil {
+			return
+		}
+		b2, err := reader.ReadByte()
+		if err != nil {
+			return
+		}
+		opcode := b1 & 0x0F
+		masked := (b2 & 0x80) != 0
+		length := int64(b2 & 0x7F)
+		if length == 126 {
+			ext := make([]byte, 2)
+			if _, err := io.ReadFull(reader, ext); err != nil {
+				return
+			}
+			length = int64(binary.BigEndian.Uint16(ext))
+		} else if length == 127 {
+			ext := make([]byte, 8)
+			if _, err := io.ReadFull(reader, ext); err != nil {
+				return
+			}
+			length = int64(binary.BigEndian.Uint64(ext))
+		}
+		var maskKey [4]byte
+		if masked {
+			if _, err := io.ReadFull(reader, maskKey[:]); err != nil {
+				return
+			}
+		}
+
+		// Handle Ping -> Pong
+		if opcode == 0x9 && length <= 125 {
+			payload := make([]byte, length)
+			if _, err := io.ReadFull(reader, payload); err != nil {
+				return
+			}
+			// Unmask if masked
+			if masked {
+				for i := int64(0); i < length; i++ {
+					payload[i] ^= maskKey[i%4]
+				}
+			}
+			_ = writeWSFrame(c.conn, 0xA, payload) // best-effort pong
+			continue
+		}
+
+		// Close frame
+		if opcode == 0x8 {
+			// Drain payload if any, then exit
+			if _, err := io.CopyN(io.Discard, reader, length); err != nil {
+				return
+			}
+			return
+		}
+
+		// For other frames, just discard payload
+		if _, err := io.CopyN(io.Discard, reader, length); err != nil {
+			return
+		}
+	}
+}
+
+// writePump sends queued messages to the client and pings periodically to keep the connection alive.
+func (c *Client) writePump() {
+	ticker := time.NewTicker(30 * time.Second)
+	defer func() {
+		ticker.Stop()
+		_ = c.conn.Close()
+	}()
+	for {
+		select {
+		case msg, ok := <-c.send:
+			if !ok {
+				// try to send close frame
+				_ = writeWSFrame(c.conn, 0x8, nil)
+				return
+			}
+			if err := writeWSFrame(c.conn, 0x1, msg); err != nil {
+				return
+			}
+		case <-ticker.C:
+			// Send a ping to keep connections alive behind proxies
+			_ = writeWSFrame(c.conn, 0x9, []byte("ping"))
+		}
+	}
+}

cmd/backoffice/main.go

@@ -0,0 +1,152 @@
+package main
+
+import (
+	"context"
+	"errors"
+	"log"
+	"net/http"
+	"os"
+	"time"
+
+	actor "git.tornberg.me/go-cart-actor/pkg/actor"
+	"git.tornberg.me/go-cart-actor/pkg/cart"
+	"github.com/matst80/slask-finder/pkg/messaging"
+	amqp "github.com/rabbitmq/amqp091-go"
+)
+
+type CartFileInfo struct {
+	ID       string      `json:"id"`
+	CartId   cart.CartId `json:"cartId"`
+	Size     int64       `json:"size"`
+	Modified time.Time   `json:"modified"`
+}
+
+func envOrDefault(key, def string) string {
+	if v := os.Getenv(key); v != "" {
+		return v
+	}
+	return def
+}
+
+func startMutationConsumer(ctx context.Context, conn *amqp.Connection, hub *Hub) error {
+	ch, err := conn.Channel()
+	if err != nil {
+		_ = conn.Close()
+		return err
+	}
+	msgs, err := messaging.DeclareBindAndConsume(ch, "cart", "mutation")
+	if err != nil {
+		_ = ch.Close()
+		return err
+	}
+
+	go func() {
+		defer ch.Close()
+
+		for {
+			select {
+			case <-ctx.Done():
+				return
+			case m, ok := <-msgs:
+				if !ok {
+					log.Fatalf("connection closed")
+					continue
+				}
+				// Log and broadcast to all websocket clients
+				log.Printf("mutation event: %s", string(m.Body))
+
+				if hub != nil {
+					select {
+					case hub.broadcast <- m.Body:
+					default:
+						// if hub queue is full, drop to avoid blocking
+					}
+				}
+				if err := m.Ack(false); err != nil {
+					log.Printf("error acknowledging message: %v", err)
+				}
+			}
+		}
+	}()
+	return nil
+}
+
+func main() {
+	dataDir := envOrDefault("DATA_DIR", "data")
+	addr := envOrDefault("ADDR", ":8080")
+	amqpURL := os.Getenv("AMQP_URL")
+
+	_ = os.MkdirAll(dataDir, 0755)
+
+	reg := cart.NewCartMultationRegistry()
+	diskStorage := actor.NewDiskStorage[cart.CartGrain](dataDir, reg)
+
+	fs := NewFileServer(dataDir, diskStorage)
+
+	hub := NewHub()
+	go hub.Run()
+
+	mux := http.NewServeMux()
+	mux.HandleFunc("GET /carts", fs.CartsHandler)
+	mux.HandleFunc("GET /cart/{id}", fs.CartHandler)
+	mux.HandleFunc("/promotions", fs.PromotionsHandler)
+	mux.HandleFunc("/vouchers", fs.VoucherHandler)
+	mux.HandleFunc("/promotion/{id}", fs.PromotionPartHandler)
+
+	mux.HandleFunc("/ws", hub.ServeWS)
+	mux.HandleFunc("/healthz", func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusOK)
+		_, _ = w.Write([]byte("ok"))
+	})
+	mux.HandleFunc("/readyz", func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusOK)
+		_, _ = w.Write([]byte("ok"))
+	})
+	mux.HandleFunc("/livez", func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusOK)
+		_, _ = w.Write([]byte("ok"))
+	})
+
+	// Global CORS middleware allowing all origins and handling preflight
+	handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Access-Control-Allow-Origin", "*")
+		w.Header().Set("Access-Control-Allow-Methods", "GET, POST, PUT, PATCH, DELETE, OPTIONS")
+		w.Header().Set("Access-Control-Allow-Headers", "Content-Type, Authorization, X-Requested-With")
+		w.Header().Set("Access-Control-Expose-Headers", "*")
+		if r.Method == http.MethodOptions {
+			w.WriteHeader(http.StatusNoContent)
+			return
+		}
+		mux.ServeHTTP(w, r)
+	})
+
+	srv := &http.Server{
+		Addr:         addr,
+		Handler:      handler,
+		ReadTimeout:  15 * time.Second,
+		WriteTimeout: 30 * time.Second,
+		IdleTimeout:  60 * time.Second,
+	}
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	if amqpURL != "" {
+		conn, err := amqp.Dial(amqpURL)
+		if err != nil {
+			log.Fatalf("failed to connect to RabbitMQ: %v", err)
+		}
+		if err := startMutationConsumer(ctx, conn, hub); err != nil {
+			log.Printf("AMQP listener disabled: %v", err)
+		} else {
+			log.Printf("AMQP listener connected")
+		}
+	}
+
+	log.Printf("backoffice HTTP listening on %s (dataDir=%s)", addr, dataDir)
+	if err := srv.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
+		log.Fatalf("http server error: %v", err)
+	}
+
+	// server stopped
+}

cmd/cart/amqp-order-handler.go

@@ -0,0 +1,64 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	amqp "github.com/rabbitmq/amqp091-go"
+)
+
+type AmqpOrderHandler struct {
+	conn  *amqp.Connection
+	queue *amqp.Queue
+}
+
+func NewAmqpOrderHandler(conn *amqp.Connection) *AmqpOrderHandler {
+	return &AmqpOrderHandler{
+		conn: conn,
+	}
+}
+
+func (h *AmqpOrderHandler) DefineQueue() error {
+	ch, err := h.conn.Channel()
+	if err != nil {
+		return fmt.Errorf("failed to open a channel: %w", err)
+	}
+	defer ch.Close()
+
+	queue, err := ch.QueueDeclare(
+		"order-queue", // name
+		false,
+		false,
+		false,
+		false,
+		nil,
+	)
+	if err != nil {
+		return fmt.Errorf("failed to declare an exchange: %w", err)
+	}
+	h.queue = &queue
+	return nil
+}
+
+func (h *AmqpOrderHandler) OrderCompleted(body []byte) error {
+	ch, err := h.conn.Channel()
+	if err != nil {
+		return fmt.Errorf("failed to open a channel: %w", err)
+	}
+	defer ch.Close()
+	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+	defer cancel()
+
+	return ch.PublishWithContext(ctx,
+		"",           // exchange
+		h.queue.Name, // routing key
+		false,        // mandatory
+		false,        // immediate
+		amqp.Publishing{
+			//DeliveryMode: amqp.,
+			ContentType: "application/json",
+			Body:        body,
+		})
+
+}

cmd/cart/checkout_builder.go

@@ -0,0 +1,120 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+
+	"git.tornberg.me/go-cart-actor/pkg/cart"
+)
+
+// CheckoutMeta carries the external / URL metadata required to build a
+// Klarna CheckoutOrder from a CartGrain snapshot. It deliberately excludes
+// any Klarna-specific response fields (HTML snippet, client token, etc.).
+type CheckoutMeta struct {
+	Terms        string
+	Checkout     string
+	Confirmation string
+	Country      string
+	Currency     string // optional override (defaults to "SEK" if empty)
+	Locale       string // optional override (defaults to "sv-se" if empty)
+}
+
+// BuildCheckoutOrderPayload converts the current cart grain + meta information
+// into a CheckoutOrder domain struct and returns its JSON-serialized payload
+// (to send to Klarna) alongside the structured CheckoutOrder object.
+//
+// This function is PURE: it does not perform any network I/O or mutate the
+// grain. The caller is responsible for:
+//
+//  1. Choosing whether to create or update the Klarna order.
+//  2. Invoking KlarnaClient.CreateOrder / UpdateOrder with the returned payload.
+//  3. Applying an InitializeCheckout mutation (or equivalent) with the
+//     resulting Klarna order id + status.
+//
+// If you later need to support different tax rates per line, you can extend
+// CartItem / Delivery to expose that data and propagate it here.
+func BuildCheckoutOrderPayload(grain *cart.CartGrain, meta *CheckoutMeta) ([]byte, *CheckoutOrder, error) {
+	if grain == nil {
+		return nil, nil, fmt.Errorf("nil grain")
+	}
+	if meta == nil {
+		return nil, nil, fmt.Errorf("nil checkout meta")
+	}
+
+	currency := meta.Currency
+	if currency == "" {
+		currency = "SEK"
+	}
+	locale := meta.Locale
+	if locale == "" {
+		locale = "sv-se"
+	}
+	country := meta.Country
+	if country == "" {
+		country = "SE" // sensible default; adjust if multi-country support changes
+	}
+
+	lines := make([]*Line, 0, len(grain.Items)+len(grain.Deliveries))
+
+	// Item lines
+	for _, it := range grain.Items {
+		if it == nil {
+			continue
+		}
+		lines = append(lines, &Line{
+			Type:           "physical",
+			Reference:      it.Sku,
+			Name:           it.Meta.Name,
+			Quantity:       it.Quantity,
+			UnitPrice:      int(it.Price.IncVat),
+			TaxRate:        it.Tax, // TODO: derive if variable tax rates are introduced
+			QuantityUnit:   "st",
+			TotalAmount:    int(it.TotalPrice.IncVat),
+			TotalTaxAmount: int(it.TotalPrice.TotalVat()),
+			ImageURL:       fmt.Sprintf("https://www.elgiganten.se%s", it.Meta.Image),
+		})
+	}
+
+	// Delivery lines
+	for _, d := range grain.Deliveries {
+		if d == nil || d.Price.IncVat <= 0 {
+			continue
+		}
+		lines = append(lines, &Line{
+			Type:           "shipping_fee",
+			Reference:      d.Provider,
+			Name:           "Delivery",
+			Quantity:       1,
+			UnitPrice:      int(d.Price.IncVat),
+			TaxRate:        2500,
+			QuantityUnit:   "st",
+			TotalAmount:    int(d.Price.IncVat),
+			TotalTaxAmount: int(d.Price.TotalVat()),
+		})
+	}
+
+	order := &CheckoutOrder{
+		PurchaseCountry:    country,
+		PurchaseCurrency:   currency,
+		Locale:             locale,
+		OrderAmount:        int(grain.TotalPrice.IncVat),
+		OrderTaxAmount:     int(grain.TotalPrice.TotalVat()),
+		OrderLines:         lines,
+		MerchantReference1: grain.Id.String(),
+		MerchantURLS: &CheckoutMerchantURLS{
+			Terms:        meta.Terms,
+			Checkout:     meta.Checkout,
+			Confirmation: meta.Confirmation,
+			Notification: "https://cart.tornberg.me/notification",
+			Validation:   "https://cart.tornberg.me/validate",
+			Push:         "https://cart.tornberg.me/push?order_id={checkout.order.id}",
+		},
+	}
+
+	payload, err := json.Marshal(order)
+	if err != nil {
+		return nil, nil, fmt.Errorf("marshal checkout order: %w", err)
+	}
+
+	return payload, order, nil
+}

cmd/cart/checkout_server.go

@@ -0,0 +1,203 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"log"
+	"net/http"
+	"time"
+
+	"git.tornberg.me/go-cart-actor/pkg/actor"
+	"git.tornberg.me/go-cart-actor/pkg/cart"
+	"git.tornberg.me/go-cart-actor/pkg/messages"
+	"git.tornberg.me/mats/go-redis-inventory/pkg/inventory"
+	amqp "github.com/rabbitmq/amqp091-go"
+)
+
+var tpl = `<!DOCTYPE html>
+<html lang="en">
+  <head>
+    <meta charset="UTF-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <title>s10r testing - checkout</title>
+  </head>
+
+  <body>
+    %s
+  </body>
+</html>
+`
+
+func (a *App) getGrainFromOrder(ctx context.Context, order *CheckoutOrder) (*cart.CartGrain, error) {
+	cartId, ok := cart.ParseCartId(order.MerchantReference1)
+	if !ok {
+		return nil, fmt.Errorf("invalid cart id in order reference: %s", order.MerchantReference1)
+	}
+	grain, err := a.pool.Get(ctx, uint64(cartId))
+	if err != nil {
+		return nil, fmt.Errorf("failed to get cart grain: %w", err)
+	}
+	return grain, nil
+}
+
+func (a *App) HandleCheckoutRequests(amqpUrl string, mux *http.ServeMux, inventoryService inventory.InventoryService) {
+	conn, err := amqp.Dial(amqpUrl)
+	if err != nil {
+		log.Fatalf("failed to connect to RabbitMQ: %v", err)
+	}
+
+	amqpListener := actor.NewAmqpListener(conn, func(id uint64, msg []actor.ApplyResult) (any, error) {
+		return &CartChangeEvent{
+			CartId:    cart.CartId(id),
+			Mutations: msg,
+		}, nil
+	})
+	amqpListener.DefineTopics()
+	a.pool.AddListener(amqpListener)
+	orderHandler := NewAmqpOrderHandler(conn)
+	orderHandler.DefineQueue()
+
+	mux.HandleFunc("/push", func(w http.ResponseWriter, r *http.Request) {
+		log.Printf("Klarna order confirmation push, method: %s", r.Method)
+		if r.Method != http.MethodPost {
+			w.WriteHeader(http.StatusMethodNotAllowed)
+			return
+		}
+		orderId := r.URL.Query().Get("order_id")
+		log.Printf("Order confirmation push: %s", orderId)
+
+		order, err := a.klarnaClient.GetOrder(r.Context(), orderId)
+
+		if err != nil {
+			log.Printf("Error creating request: %v\n", err)
+			w.WriteHeader(http.StatusInternalServerError)
+			return
+		}
+
+		grain, err := a.getGrainFromOrder(r.Context(), order)
+		if err != nil {
+			logger.ErrorContext(r.Context(), "Unable to get grain from klarna order", "error", err.Error())
+			w.WriteHeader(http.StatusInternalServerError)
+			return
+		}
+
+		if inventoryService != nil {
+			inventoryRequests := getInventoryRequests(grain.Items)
+			err = inventoryService.ReserveInventory(r.Context(), inventoryRequests...)
+
+			if err != nil {
+				logger.WarnContext(r.Context(), "placeorder inventory reservation failed")
+				w.WriteHeader(http.StatusNotAcceptable)
+				return
+			}
+			a.pool.Apply(r.Context(), uint64(grain.Id), &messages.InventoryReserved{
+				Id:     grain.Id.String(),
+				Status: "success",
+			})
+		}
+
+		err = confirmOrder(r.Context(), order, orderHandler)
+		if err != nil {
+			log.Printf("Error confirming order: %v\n", err)
+			w.WriteHeader(http.StatusInternalServerError)
+			return
+		}
+
+		err = triggerOrderCompleted(r.Context(), a.server, order)
+		if err != nil {
+			log.Printf("Error processing cart message: %v\n", err)
+			w.WriteHeader(http.StatusInternalServerError)
+			return
+		}
+		err = a.klarnaClient.AcknowledgeOrder(r.Context(), orderId)
+		if err != nil {
+			log.Printf("Error acknowledging order: %v\n", err)
+		}
+
+		w.WriteHeader(http.StatusOK)
+	})
+
+	mux.HandleFunc("GET /checkout", a.server.CheckoutHandler(func(order *CheckoutOrder, w http.ResponseWriter) error {
+		w.Header().Set("Content-Type", "text/html; charset=utf-8")
+		w.Header().Set("Permissions-Policy", "payment=(self \"https://js.stripe.com\" \"https://m.stripe.network\" \"https://js.playground.kustom.co\")")
+		w.WriteHeader(http.StatusOK)
+		_, err := fmt.Fprintf(w, tpl, order.HTMLSnippet)
+		return err
+	}))
+
+	mux.HandleFunc("GET /confirmation/{order_id}", func(w http.ResponseWriter, r *http.Request) {
+
+		orderId := r.PathValue("order_id")
+		order, err := a.klarnaClient.GetOrder(r.Context(), orderId)
+
+		if err != nil {
+			w.WriteHeader(http.StatusInternalServerError)
+			w.Write([]byte(err.Error()))
+			return
+		}
+
+		w.Header().Set("Content-Type", "text/html; charset=utf-8")
+		if order.Status == "checkout_complete" {
+			http.SetCookie(w, &http.Cookie{
+				Name:     "cartid",
+				Value:    "",
+				Path:     "/",
+				Secure:   true,
+				HttpOnly: true,
+				Expires:  time.Unix(0, 0),
+				SameSite: http.SameSiteLaxMode,
+			})
+		}
+
+		w.WriteHeader(http.StatusOK)
+		fmt.Fprintf(w, tpl, order.HTMLSnippet)
+	})
+	mux.HandleFunc("/notification", func(w http.ResponseWriter, r *http.Request) {
+		log.Printf("Klarna order notification, method: %s", r.Method)
+		logger.InfoContext(r.Context(), "Klarna order notification received", "method", r.Method)
+		if r.Method != "POST" {
+			w.WriteHeader(http.StatusMethodNotAllowed)
+			return
+		}
+		order := &CheckoutOrder{}
+		err := json.NewDecoder(r.Body).Decode(order)
+		if err != nil {
+			w.WriteHeader(http.StatusBadRequest)
+		}
+		log.Printf("Klarna order notification: %s", order.ID)
+		logger.InfoContext(r.Context(), "Klarna order notification received", "order_id", order.ID)
+
+		w.WriteHeader(http.StatusOK)
+	})
+	mux.HandleFunc("POST /validate", func(w http.ResponseWriter, r *http.Request) {
+		log.Printf("Klarna order validation, method: %s", r.Method)
+		if r.Method != "POST" {
+			w.WriteHeader(http.StatusMethodNotAllowed)
+			return
+		}
+		order := &CheckoutOrder{}
+		err := json.NewDecoder(r.Body).Decode(order)
+		if err != nil {
+			w.WriteHeader(http.StatusBadRequest)
+		}
+		logger.InfoContext(r.Context(), "Klarna order validation received", "order_id", order.ID, "cart_id", order.MerchantReference1)
+		grain, err := a.getGrainFromOrder(r.Context(), order)
+		if err != nil {
+			logger.ErrorContext(r.Context(), "Unable to get grain from klarna order", "error", err.Error())
+			w.WriteHeader(http.StatusInternalServerError)
+			return
+		}
+		if inventoryService != nil {
+			inventoryRequests := getInventoryRequests(grain.Items)
+			_, err = inventoryService.ReservationCheck(r.Context(), inventoryRequests...)
+			if err != nil {
+				logger.WarnContext(r.Context(), "placeorder inventory check failed")
+				w.WriteHeader(http.StatusNotAcceptable)
+				return
+			}
+		}
+
+		w.WriteHeader(http.StatusOK)
+	})
+}

cmd/cart/k8s-host-discovery.go

@@ -0,0 +1,60 @@
+package main
+
+import (
+	"log"
+
+	"git.tornberg.me/go-cart-actor/pkg/actor"
+	"git.tornberg.me/go-cart-actor/pkg/cart"
+	"git.tornberg.me/go-cart-actor/pkg/discovery"
+	"k8s.io/client-go/kubernetes"
+	"k8s.io/client-go/rest"
+)
+
+func GetDiscovery() discovery.Discovery {
+	if podIp == "" {
+		return nil
+	}
+
+	config, kerr := rest.InClusterConfig()
+
+	if kerr != nil {
+		log.Fatalf("Error creating kubernetes client: %v\n", kerr)
+	}
+	client, err := kubernetes.NewForConfig(config)
+	if err != nil {
+		log.Fatalf("Error creating client: %v\n", err)
+	}
+	return discovery.NewK8sDiscovery(client)
+}
+
+func UseDiscovery(pool actor.GrainPool[*cart.CartGrain]) {
+
+	go func(hw discovery.Discovery) {
+		if hw == nil {
+			log.Print("No discovery service available")
+			return
+		}
+		ch, err := hw.Watch()
+		if err != nil {
+			log.Printf("Discovery error: %v", err)
+			return
+		}
+		for evt := range ch {
+			if evt.Host == "" {
+				continue
+			}
+			switch evt.IsReady {
+			case false:
+				if pool.IsKnown(evt.Host) {
+					log.Printf("Host %s is not ready, removing", evt.Host)
+					pool.RemoveHost(evt.Host)
+				}
+			default:
+				if !pool.IsKnown(evt.Host) {
+					log.Printf("Discovered host %s", evt.Host)
+					pool.AddRemoteHost(evt.Host)
+				}
+			}
+		}
+	}(GetDiscovery())
+}

cmd/cart/klarna-client.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"context"
 	"encoding/json"
 	"fmt"
 	"io"
@@ -30,11 +31,14 @@ const (
 	KlarnaPlaygroundUrl = "https://api.playground.klarna.com"
 )
 
-func (k *KlarnaClient) GetOrder(orderId string) (*CheckoutOrder, error) {
+func (k *KlarnaClient) GetOrder(ctx context.Context, orderId string) (*CheckoutOrder, error) {
 	req, err := http.NewRequest("GET", k.Url+"/checkout/v3/orders/"+orderId, nil)
 	if err != nil {
 		return nil, err
 	}
+	spanCtx, span := tracer.Start(ctx, "Get klarna order")
+	defer span.End()
+	req = req.WithContext(spanCtx)
 	req.Header.Add("Content-Type", "application/json")
 	req.SetBasicAuth(k.UserName, k.Password)
 
@@ -64,13 +68,15 @@ func (k *KlarnaClient) getOrderResponse(res *http.Response) (*CheckoutOrder, err
 	return nil, fmt.Errorf("%s", res.Status)
 }
 
-func (k *KlarnaClient) CreateOrder(reader io.Reader) (*CheckoutOrder, error) {
+func (k *KlarnaClient) CreateOrder(ctx context.Context, reader io.Reader) (*CheckoutOrder, error) {
 	//bytes.NewReader(reply.Payload)
 	req, err := http.NewRequest("POST", k.Url+"/checkout/v3/orders", reader)
 	if err != nil {
 		return nil, err
 	}
-
+	spanCtx, span := tracer.Start(ctx, "Create klarna order")
+	defer span.End()
+	req = req.WithContext(spanCtx)
 	req.Header.Add("Content-Type", "application/json")
 	req.SetBasicAuth(k.UserName, k.Password)
 
@@ -82,13 +88,16 @@ func (k *KlarnaClient) CreateOrder(reader io.Reader) (*CheckoutOrder, error) {
 	return k.getOrderResponse(res)
 }
 
-func (k *KlarnaClient) UpdateOrder(orderId string, reader io.Reader) (*CheckoutOrder, error) {
+func (k *KlarnaClient) UpdateOrder(ctx context.Context, orderId string, reader io.Reader) (*CheckoutOrder, error) {
 	//bytes.NewReader(reply.Payload)
 	req, err := http.NewRequest("POST", fmt.Sprintf("%s/checkout/v3/orders/%s", k.Url, orderId), reader)
 	if err != nil {
 		return nil, err
 	}
 
+	spanCtx, span := tracer.Start(ctx, "Update klarna order")
+	defer span.End()
+	req = req.WithContext(spanCtx)
 	req.Header.Add("Content-Type", "application/json")
 	req.SetBasicAuth(k.UserName, k.Password)
 
@@ -100,12 +109,14 @@ func (k *KlarnaClient) UpdateOrder(orderId string, reader io.Reader) (*CheckoutO
 	return k.getOrderResponse(res)
 }
 
-func (k *KlarnaClient) AbortOrder(orderId string) error {
+func (k *KlarnaClient) AbortOrder(ctx context.Context, orderId string) error {
 	req, err := http.NewRequest("POST", fmt.Sprintf("%s/checkout/v3/orders/%s/abort", k.Url, orderId), nil)
 	if err != nil {
 		return err
 	}
-
+	spanCtx, span := tracer.Start(ctx, "Abort klarna order")
+	defer span.End()
+	req = req.WithContext(spanCtx)
 	req.SetBasicAuth(k.UserName, k.Password)
 
 	_, err = http.DefaultClient.Do(req)
@@ -113,11 +124,14 @@ func (k *KlarnaClient) AbortOrder(orderId string) error {
 }
 
 // ordermanagement/v1/orders/{order_id}/acknowledge
-func (k *KlarnaClient) AcknowledgeOrder(orderId string) error {
+func (k *KlarnaClient) AcknowledgeOrder(ctx context.Context, orderId string) error {
 	req, err := http.NewRequest("POST", fmt.Sprintf("%s/ordermanagement/v1/orders/%s/acknowledge", k.Url, orderId), nil)
 	if err != nil {
 		return err
 	}
+	spanCtx, span := tracer.Start(ctx, "Acknowledge klarna order")
+	defer span.End()
+	req = req.WithContext(spanCtx)
 	id := uuid.New()
 
 	req.SetBasicAuth(k.UserName, k.Password)

cmd/cart/main.go

@@ -0,0 +1,290 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"log"
+	"net"
+	"net/http"
+	"net/http/pprof"
+	"os"
+	"os/signal"
+	"strings"
+	"time"
+
+	"git.tornberg.me/go-cart-actor/pkg/actor"
+	"git.tornberg.me/go-cart-actor/pkg/cart"
+	messages "git.tornberg.me/go-cart-actor/pkg/messages"
+	"git.tornberg.me/go-cart-actor/pkg/promotions"
+	"git.tornberg.me/go-cart-actor/pkg/proxy"
+	"git.tornberg.me/go-cart-actor/pkg/voucher"
+	"git.tornberg.me/mats/go-redis-inventory/pkg/inventory"
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promauto"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+	"github.com/redis/go-redis/v9"
+	"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
+)
+
+var (
+	grainSpawns = promauto.NewCounter(prometheus.CounterOpts{
+		Name: "cart_grain_spawned_total",
+		Help: "The total number of spawned grains",
+	})
+)
+
+func init() {
+	os.Mkdir("data", 0755)
+}
+
+type App struct {
+	pool         *actor.SimpleGrainPool[cart.CartGrain]
+	server       *PoolServer
+	klarnaClient *KlarnaClient
+}
+
+var podIp = os.Getenv("POD_IP")
+var name = os.Getenv("POD_NAME")
+var amqpUrl = os.Getenv("AMQP_URL")
+var redisAddress = os.Getenv("REDIS_ADDRESS")
+var redisPassword = os.Getenv("REDIS_PASSWORD")
+
+func getCountryFromHost(host string) string {
+	if strings.Contains(strings.ToLower(host), "-no") {
+		return "no"
+	}
+	if strings.Contains(strings.ToLower(host), "-se") {
+		return "se"
+	}
+	return ""
+}
+
+type MutationContext struct {
+	VoucherService voucher.Service
+}
+
+type CartChangeEvent struct {
+	CartId    cart.CartId         `json:"cartId"`
+	Mutations []actor.ApplyResult `json:"mutations"`
+}
+
+func main() {
+
+	controlPlaneConfig := actor.DefaultServerConfig()
+
+	promotionData, err := promotions.LoadStateFile("data/promotions.json")
+	if err != nil {
+		log.Printf("Error loading promotions: %v\n", err)
+	}
+
+	log.Printf("loaded %d promotions", len(promotionData.State.Promotions))
+
+	promotionService := promotions.NewPromotionService(nil)
+
+	reg := cart.NewCartMultationRegistry()
+	reg.RegisterProcessor(
+		actor.NewMutationProcessor(func(ctx context.Context, g *cart.CartGrain) error {
+			_, span := tracer.Start(ctx, "Totals and promotions")
+			defer span.End()
+			g.UpdateTotals()
+
+			promotionCtx := promotions.NewContextFromCart(g, promotions.WithNow(time.Now()), promotions.WithCustomerSegment("vip"))
+			_, actions := promotionService.EvaluateAll(promotionData.State.Promotions, promotionCtx)
+			for _, action := range actions {
+				log.Printf("apply: %+v", action)
+				g.UpdateTotals()
+			}
+			return nil
+		}),
+	)
+
+	diskStorage := actor.NewDiskStorage[cart.CartGrain]("data", reg)
+	poolConfig := actor.GrainPoolConfig[cart.CartGrain]{
+		MutationRegistry: reg,
+		Storage:          diskStorage,
+		Spawn: func(ctx context.Context, id uint64) (actor.Grain[cart.CartGrain], error) {
+			_, span := tracer.Start(ctx, fmt.Sprintf("Spawn cart id %d", id))
+			defer span.End()
+			grainSpawns.Inc()
+			ret := cart.NewCartGrain(id, time.Now())
+			// Set baseline lastChange at spawn; replay may update it to last event timestamp.
+
+			err := diskStorage.LoadEvents(ctx, id, ret)
+
+			return ret, err
+		},
+		SpawnHost: func(host string) (actor.Host, error) {
+			return proxy.NewRemoteHost(host)
+		},
+		TTL:      15 * time.Minute,
+		PoolSize: 2 * 65535,
+		Hostname: podIp,
+	}
+
+	pool, err := actor.NewSimpleGrainPool(poolConfig)
+	if err != nil {
+		log.Fatalf("Error creating cart pool: %v\n", err)
+	}
+
+	pool.SetPubSub(actor.NewPubSub(func(id uint64, event actor.Event) {
+		grain, _ := pool.Get(context.Background(), id)
+		if sub, ok := any(grain).(actor.Subscribable); ok {
+			sub.Notify(event)
+		}
+	}))
+
+	klarnaClient := NewKlarnaClient(KlarnaPlaygroundUrl, os.Getenv("KLARNA_API_USERNAME"), os.Getenv("KLARNA_API_PASSWORD"))
+	rdb := redis.NewClient(&redis.Options{
+		Addr:     redisAddress,
+		Password: redisPassword,
+		DB:       0,
+	})
+	inventoryService, err := inventory.NewRedisInventoryService(rdb)
+	if err != nil {
+		log.Fatalf("Error creating inventory service: %v\n", err)
+	}
+
+	syncedServer := NewPoolServer(pool, fmt.Sprintf("%s, %s", name, podIp), klarnaClient, inventoryService)
+
+	app := &App{
+		pool:         pool,
+		server:       syncedServer,
+		klarnaClient: klarnaClient,
+	}
+
+	mux := http.NewServeMux()
+	debugMux := http.NewServeMux()
+
+	if amqpUrl == "" {
+		log.Printf("no connection to amqp defined")
+	} else {
+		app.HandleCheckoutRequests(amqpUrl, mux, inventoryService)
+	}
+
+	grpcSrv, err := actor.NewControlServer[*cart.CartGrain](controlPlaneConfig, pool)
+	if err != nil {
+		log.Fatalf("Error starting control plane gRPC server: %v\n", err)
+	}
+	defer grpcSrv.GracefulStop()
+
+	// go diskStorage.SaveLoop(10 * time.Second)
+	UseDiscovery(pool)
+
+	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt)
+	defer stop()
+
+	otelShutdown, err := setupOTelSDK(ctx)
+	if err != nil {
+		log.Fatalf("Unable to start otel %v", err)
+	}
+
+	syncedServer.Serve(mux)
+	// only for local
+	mux.HandleFunc("GET /add/remote/{host}", func(w http.ResponseWriter, r *http.Request) {
+		pool.AddRemote(r.PathValue("host"))
+	})
+
+	debugMux.HandleFunc("/debug/pprof/", pprof.Index)
+	debugMux.HandleFunc("/debug/pprof/cmdline", pprof.Cmdline)
+	debugMux.HandleFunc("/debug/pprof/profile", pprof.Profile)
+	debugMux.HandleFunc("/debug/pprof/symbol", pprof.Symbol)
+	debugMux.HandleFunc("/debug/pprof/trace", pprof.Trace)
+	debugMux.Handle("/metrics", promhttp.Handler())
+	mux.HandleFunc("/healthz", func(w http.ResponseWriter, r *http.Request) {
+		// Grain pool health: simple capacity check (mirrors previous GrainHandler.IsHealthy)
+		grainCount, capacity := app.pool.LocalUsage()
+		if grainCount >= capacity {
+			w.WriteHeader(http.StatusInternalServerError)
+			w.Write([]byte("grain pool at capacity"))
+			return
+		}
+		if !pool.IsHealthy() {
+			w.WriteHeader(http.StatusInternalServerError)
+			w.Write([]byte("control plane not healthy"))
+			return
+		}
+		w.WriteHeader(http.StatusOK)
+		w.Write([]byte("ok"))
+	})
+	mux.HandleFunc("/readyz", func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusOK)
+		w.Write([]byte("ok"))
+	})
+	mux.HandleFunc("/livez", func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusOK)
+		w.Write([]byte("ok"))
+	})
+
+	mux.HandleFunc("/version", func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusOK)
+		w.Write([]byte("1.0.0"))
+	})
+
+	mux.HandleFunc("/openapi.json", ServeEmbeddedOpenAPI)
+
+	srv := &http.Server{
+		Addr:         ":8080",
+		BaseContext:  func(net.Listener) context.Context { return ctx },
+		ReadTimeout:  10 * time.Second,
+		WriteTimeout: 20 * time.Second,
+		Handler:      otelhttp.NewHandler(mux, "/"),
+	}
+
+	defer func() {
+
+		fmt.Println("Shutting down due to signal")
+		otelShutdown(context.Background())
+		diskStorage.Close()
+		pool.Close()
+
+	}()
+
+	srvErr := make(chan error, 1)
+	go func() {
+		srvErr <- srv.ListenAndServe()
+	}()
+
+	log.Print("Server started at port 8080")
+
+	go http.ListenAndServe(":8081", debugMux)
+
+	select {
+	case err = <-srvErr:
+		// Error when starting HTTP server.
+		log.Fatalf("Unable to start server: %v", err)
+	case <-ctx.Done():
+		// Wait for first CTRL+C.
+		// Stop receiving signal notifications as soon as possible.
+		stop()
+	}
+
+}
+
+func triggerOrderCompleted(ctx context.Context, syncedServer *PoolServer, order *CheckoutOrder) error {
+	mutation := &messages.OrderCreated{
+		OrderId: order.ID,
+		Status:  order.Status,
+	}
+	cid, ok := cart.ParseCartId(order.MerchantReference1)
+	if !ok {
+		return fmt.Errorf("invalid cart id in order reference: %s", order.MerchantReference1)
+	}
+	_, applyErr := syncedServer.Apply(ctx, uint64(cid), mutation)
+
+	return applyErr
+}
+
+func confirmOrder(ctx context.Context, order *CheckoutOrder, orderHandler *AmqpOrderHandler) error {
+	orderToSend, err := json.Marshal(order)
+	if err != nil {
+		return err
+	}
+
+	err = orderHandler.OrderCompleted(orderToSend)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}

cmd/cart/openapi.json

@@ -0,0 +1,852 @@
+{
+  "openapi": "3.0.3",
+  "info": {
+    "title": "Cart Service API",
+    "description": "HTTP API for shopping cart operations (cookie-based or explicit id): retrieve cart, add/replace items, update quantity, manage deliveries.",
+    "version": "1.0.0"
+  },
+  "servers": [
+    {
+      "url": "https://cart.tornberg.me",
+      "description": "Production server"
+    },
+    {
+      "url": "http://localhost:8080",
+      "description": "Local development (cart API mounted under /cart)"
+    }
+  ],
+  "paths": {
+    "/cart": {
+      "get": {
+        "summary": "Get (or create) current cart (cookie based)",
+        "description": "Returns the current cart. If no cartid cookie is present a new cart is created and Set-Cart-Id response header plus a Set-Cookie header are sent.",
+        "responses": {
+          "200": {
+            "description": "Cart retrieved",
+            "headers": {
+              "Set-Cart-Id": {
+                "description": "Returned when a new cart was created this request",
+                "schema": { "type": "string" }
+              },
+              "X-Pod-Name": {
+                "description": "Pod identifier serving the request",
+                "schema": { "type": "string" }
+              }
+            },
+            "content": {
+              "application/json": {
+                "schema": { "$ref": "#/components/schemas/CartGrain" }
+              }
+            }
+          },
+          "500": { "description": "Server error" }
+        }
+      },
+      "post": {
+        "summary": "Add single SKU (body)",
+        "description": "Adds (or increases quantity of) a single SKU using request body.",
+        "requestBody": {
+          "required": true,
+          "content": {
+            "application/json": {
+              "schema": { "$ref": "#/components/schemas/AddRequest" }
+            }
+          }
+        },
+        "responses": {
+          "200": {
+            "description": "Item added",
+            "content": {
+              "application/json": {
+                "schema": { "$ref": "#/components/schemas/CartGrain" }
+              }
+            }
+          },
+          "400": { "description": "Invalid request body" },
+          "500": { "description": "Server error" }
+        }
+      },
+      "put": {
+        "summary": "Change quantity of an item",
+        "requestBody": {
+          "required": true,
+          "content": {
+            "application/json": {
+              "schema": { "$ref": "#/components/schemas/ChangeQuantity" }
+            }
+          }
+        },
+        "responses": {
+          "200": {
+            "description": "Quantity updated",
+            "content": {
+              "application/json": {
+                "schema": { "$ref": "#/components/schemas/CartGrain" }
+              }
+            }
+          },
+          "400": { "description": "Invalid request body" },
+          "500": { "description": "Server error" }
+        }
+      },
+      "delete": {
+        "summary": "Clear cart cookie (logical cart reused only if referenced later)",
+        "description": "Removes the cartid cookie by expiring it. Does not mutate server-side cart state.",
+        "responses": {
+          "200": { "description": "Cookie cleared (empty body)" }
+        }
+      }
+    },
+    "/cart/add/{sku}": {
+      "get": {
+        "summary": "Add a SKU (path)",
+        "description": "Adds a single SKU with implicit quantity 1. Country inferred from Host header (-se / -no).",
+        "parameters": [{ "$ref": "#/components/parameters/SkuParam" }],
+        "responses": {
+          "200": {
+            "description": "Item added",
+            "content": {
+              "application/json": {
+                "schema": { "$ref": "#/components/schemas/CartGrain" }
+              }
+            }
+          },
+          "500": { "description": "Server error" }
+        }
+      }
+    },
+    "/cart/add": {
+      "post": {
+        "summary": "Add multiple items (append)",
+        "description": "Adds multiple items to the cart without clearing existing contents.",
+        "requestBody": {
+          "required": true,
+          "content": {
+            "application/json": {
+              "schema": { "$ref": "#/components/schemas/SetCartItems" }
+            }
+          }
+        },
+        "responses": {
+          "200": {
+            "description": "Items added",
+            "content": {
+              "application/json": {
+                "schema": { "$ref": "#/components/schemas/CartGrain" }
+              }
+            }
+          },
+          "400": { "description": "Invalid body" },
+          "500": { "description": "Server error" }
+        }
+      }
+    },
+    "/cart/set": {
+      "post": {
+        "summary": "Replace cart contents",
+        "description": "Clears the cart first, then adds the provided items (idempotent with respect to target set).",
+        "requestBody": {
+          "required": true,
+          "content": {
+            "application/json": {
+              "schema": { "$ref": "#/components/schemas/SetCartItems" }
+            }
+          }
+        },
+        "responses": {
+          "200": {
+            "description": "Cart replaced",
+            "content": {
+              "application/json": {
+                "schema": { "$ref": "#/components/schemas/CartGrain" }
+              }
+            }
+          },
+          "400": { "description": "Invalid body" },
+          "500": { "description": "Server error" }
+        }
+      }
+    },
+    "/cart/{itemId}": {
+      "delete": {
+        "summary": "Remove item by line id",
+        "parameters": [
+          {
+            "name": "itemId",
+            "in": "path",
+            "required": true,
+            "schema": { "type": "integer", "format": "int64", "minimum": 0 },
+            "description": "Internal cart line item identifier (not SKU)."
+          }
+        ],
+        "responses": {
+          "200": {
+            "description": "Item removed",
+            "content": {
+              "application/json": {
+                "schema": { "$ref": "#/components/schemas/CartGrain" }
+              }
+            }
+          },
+          "400": { "description": "Bad id" },
+          "500": { "description": "Server error" }
+        }
+      }
+    },
+    "/cart/delivery": {
+      "post": {
+        "summary": "Set (add) delivery",
+        "description": "Adds a delivery option referencing one or more line item ids.",
+        "requestBody": {
+          "required": true,
+          "content": {
+            "application/json": {
+              "schema": { "$ref": "#/components/schemas/SetDeliveryRequest" }
+            }
+          }
+        },
+        "responses": {
+          "200": {
+            "description": "Delivery added/updated",
+            "content": {
+              "application/json": {
+                "schema": { "$ref": "#/components/schemas/CartGrain" }
+              }
+            }
+          },
+          "400": { "description": "Invalid body" },
+          "500": { "description": "Server error" }
+        }
+      }
+    },
+    "/cart/delivery/{deliveryId}": {
+      "delete": {
+        "summary": "Remove delivery",
+        "parameters": [{ "$ref": "#/components/parameters/DeliveryIdParam" }],
+        "responses": {
+          "200": {
+            "description": "Delivery removed",
+            "content": {
+              "application/json": {
+                "schema": { "$ref": "#/components/schemas/CartGrain" }
+              }
+            }
+          },
+          "400": { "description": "Bad id" },
+          "500": { "description": "Server error" }
+        }
+      }
+    },
+    "/cart/delivery/{deliveryId}/pickupPoint": {
+      "put": {
+        "summary": "Set pickup point for delivery",
+        "parameters": [{ "$ref": "#/components/parameters/DeliveryIdParam" }],
+        "requestBody": {
+          "required": true,
+          "content": {
+            "application/json": {
+              "schema": { "$ref": "#/components/schemas/PickupPoint" }
+            }
+          }
+        },
+        "responses": {
+          "200": {
+            "description": "Pickup point set",
+            "content": {
+              "application/json": {
+                "schema": { "$ref": "#/components/schemas/CartGrain" }
+              }
+            }
+          },
+          "400": { "description": "Invalid body" },
+          "500": { "description": "Server error" }
+        }
+      }
+    },
+    "/cart/voucher": {
+      "put": {
+        "summary": "Add voucher to cart",
+        "requestBody": {
+          "required": true,
+          "content": {
+            "application/json": {
+              "schema": { "$ref": "#/components/schemas/AddVoucherRequest" }
+            }
+          }
+        },
+        "responses": {
+          "200": {
+            "description": "Voucher added",
+            "content": {
+              "application/json": {
+                "schema": { "$ref": "#/components/schemas/CartGrain" }
+              }
+            }
+          },
+          "400": { "description": "Invalid body" },
+          "500": { "description": "Server error" }
+        }
+      }
+    },
+    "/cart/subscription-details": {
+      "put": {
+        "summary": "Upsert subscription details",
+        "requestBody": {
+          "required": true,
+          "content": {
+            "application/json": {
+              "schema": {
+                "$ref": "#/components/schemas/UpsertSubscriptionDetails"
+              }
+            }
+          }
+        },
+        "responses": {
+          "200": {
+            "description": "Subscription details updated",
+            "content": {
+              "application/json": {
+                "schema": { "$ref": "#/components/schemas/CartGrain" }
+              }
+            }
+          },
+          "400": { "description": "Invalid body" },
+          "500": { "description": "Server error" }
+        }
+      }
+    },
+    "/cart/voucher/{voucherId}": {
+      "delete": {
+        "summary": "Remove voucher from cart",
+        "parameters": [{ "$ref": "#/components/parameters/VoucherIdParam" }],
+        "responses": {
+          "200": {
+            "description": "Voucher removed",
+            "content": {
+              "application/json": {
+                "schema": { "$ref": "#/components/schemas/CartGrain" }
+              }
+            }
+          },
+          "400": { "description": "Invalid id" },
+          "500": { "description": "Server error" }
+        }
+      }
+    },
+    "/cart/byid/{id}": {
+      "get": {
+        "summary": "Get cart by explicit id",
+        "parameters": [{ "$ref": "#/components/parameters/CartIdParam" }],
+        "responses": {
+          "200": {
+            "description": "Cart retrieved",
+            "content": {
+              "application/json": {
+                "schema": { "$ref": "#/components/schemas/CartGrain" }
+              }
+            }
+          },
+          "400": { "description": "Invalid id" },
+          "500": { "description": "Server error" }
+        }
+      },
+      "post": {
+        "summary": "Add single SKU (body) by cart id",
+        "parameters": [{ "$ref": "#/components/parameters/CartIdParam" }],
+        "requestBody": {
+          "required": true,
+          "content": {
+            "application/json": {
+              "schema": { "$ref": "#/components/schemas/AddRequest" }
+            }
+          }
+        },
+        "responses": {
+          "200": {
+            "description": "Item added",
+            "content": {
+              "application/json": {
+                "schema": { "$ref": "#/components/schemas/CartGrain" }
+              }
+            }
+          },
+          "400": { "description": "Invalid body" },
+          "500": { "description": "Server error" }
+        }
+      },
+      "put": {
+        "summary": "Change quantity (by id variant)",
+        "parameters": [{ "$ref": "#/components/parameters/CartIdParam" }],
+        "requestBody": {
+          "required": true,
+          "content": {
+            "application/json": {
+              "schema": { "$ref": "#/components/schemas/ChangeQuantity" }
+            }
+          }
+        },
+        "responses": {
+          "200": {
+            "description": "Quantity updated",
+            "content": {
+              "application/json": {
+                "schema": { "$ref": "#/components/schemas/CartGrain" }
+              }
+            }
+          },
+          "400": { "description": "Invalid body" },
+          "500": { "description": "Server error" }
+        }
+      }
+    },
+    "/cart/byid/{id}/add/{sku}": {
+      "get": {
+        "summary": "Add SKU (path) by explicit cart id",
+        "parameters": [
+          { "$ref": "#/components/parameters/CartIdParam" },
+          { "$ref": "#/components/parameters/SkuParam" }
+        ],
+        "responses": {
+          "200": {
+            "description": "Item added",
+            "content": {
+              "application/json": {
+                "schema": { "$ref": "#/components/schemas/CartGrain" }
+              }
+            }
+          },
+          "400": { "description": "Invalid id/sku" },
+          "500": { "description": "Server error" }
+        }
+      }
+    },
+    "/cart/byid/{id}/{itemId}": {
+      "delete": {
+        "summary": "Remove item (by id variant)",
+        "parameters": [
+          { "$ref": "#/components/parameters/CartIdParam" },
+          {
+            "name": "itemId",
+            "in": "path",
+            "required": true,
+            "schema": { "type": "integer", "format": "int64", "minimum": 0 }
+          }
+        ],
+        "responses": {
+          "200": {
+            "description": "Item removed",
+            "content": {
+              "application/json": {
+                "schema": { "$ref": "#/components/schemas/CartGrain" }
+              }
+            }
+          },
+          "400": { "description": "Invalid id" },
+          "500": { "description": "Server error" }
+        }
+      }
+    },
+    "/cart/byid/{id}/delivery": {
+      "post": {
+        "summary": "Set delivery (by id variant)",
+        "parameters": [{ "$ref": "#/components/parameters/CartIdParam" }],
+        "requestBody": {
+          "required": true,
+          "content": {
+            "application/json": {
+              "schema": { "$ref": "#/components/schemas/SetDeliveryRequest" }
+            }
+          }
+        },
+        "responses": {
+          "200": {
+            "description": "Delivery added/updated",
+            "content": {
+              "application/json": {
+                "schema": { "$ref": "#/components/schemas/CartGrain" }
+              }
+            }
+          },
+          "400": { "description": "Invalid body" },
+          "500": { "description": "Server error" }
+        }
+      }
+    },
+    "/cart/byid/{id}/delivery/{deliveryId}": {
+      "delete": {
+        "summary": "Remove delivery (by id variant)",
+        "parameters": [
+          { "$ref": "#/components/parameters/CartIdParam" },
+          { "$ref": "#/components/parameters/DeliveryIdParam" }
+        ],
+        "responses": {
+          "200": {
+            "description": "Delivery removed",
+            "content": {
+              "application/json": {
+                "schema": { "$ref": "#/components/schemas/CartGrain" }
+              }
+            }
+          },
+          "400": { "description": "Invalid ids" },
+          "500": { "description": "Server error" }
+        }
+      }
+    },
+    "/cart/byid/{id}/delivery/{deliveryId}/pickupPoint": {
+      "put": {
+        "summary": "Set pickup point (by id variant)",
+        "parameters": [
+          { "$ref": "#/components/parameters/CartIdParam" },
+          { "$ref": "#/components/parameters/DeliveryIdParam" }
+        ],
+        "requestBody": {
+          "required": true,
+          "content": {
+            "application/json": {
+              "schema": { "$ref": "#/components/schemas/PickupPoint" }
+            }
+          }
+        },
+        "responses": {
+          "200": {
+            "description": "Pickup point updated",
+            "content": {
+              "application/json": {
+                "schema": { "$ref": "#/components/schemas/CartGrain" }
+              }
+            }
+          },
+          "400": { "description": "Invalid body" },
+          "500": { "description": "Server error" }
+        }
+      }
+    },
+    "/cart/byid/{id}/voucher": {
+      "put": {
+        "summary": "Add voucher (by id variant)",
+        "parameters": [{ "$ref": "#/components/parameters/CartIdParam" }],
+        "requestBody": {
+          "required": true,
+          "content": {
+            "application/json": {
+              "schema": { "$ref": "#/components/schemas/AddVoucherRequest" }
+            }
+          }
+        },
+        "responses": {
+          "200": {
+            "description": "Voucher added",
+            "content": {
+              "application/json": {
+                "schema": { "$ref": "#/components/schemas/CartGrain" }
+              }
+            }
+          },
+          "400": { "description": "Invalid body" },
+          "500": { "description": "Server error" }
+        }
+      }
+    },
+    "/cart/byid/{id}/voucher/{voucherId}": {
+      "delete": {
+        "summary": "Remove voucher (by id variant)",
+        "parameters": [
+          { "$ref": "#/components/parameters/CartIdParam" },
+          { "$ref": "#/components/parameters/VoucherIdParam" }
+        ],
+        "responses": {
+          "200": {
+            "description": "Voucher removed",
+            "content": {
+              "application/json": {
+                "schema": { "$ref": "#/components/schemas/CartGrain" }
+              }
+            }
+          },
+          "400": { "description": "Invalid ids" },
+          "500": { "description": "Server error" }
+        }
+      }
+    },
+    "/healthz": {
+      "get": {
+        "summary": "Liveness & capacity probe",
+        "responses": {
+          "200": { "description": "Healthy" },
+          "500": { "description": "Unhealthy" }
+        }
+      }
+    },
+    "/readyz": {
+      "get": {
+        "summary": "Readiness probe",
+        "responses": {
+          "200": { "description": "Ready" }
+        }
+      }
+    },
+    "/livez": {
+      "get": {
+        "summary": "Liveness probe",
+        "responses": {
+          "200": { "description": "Alive" }
+        }
+      }
+    },
+    "/version": {
+      "get": {
+        "summary": "Service version",
+        "responses": {
+          "200": {
+            "description": "Version string",
+            "content": {
+              "text/plain": {
+                "schema": { "type": "string", "example": "1.0.0" }
+              }
+            }
+          }
+        }
+      }
+    }
+  },
+  "components": {
+    "parameters": {
+      "SkuParam": {
+        "name": "sku",
+        "in": "path",
+        "required": true,
+        "schema": { "type": "string" }
+      },
+      "CartIdParam": {
+        "name": "id",
+        "in": "path",
+        "required": true,
+        "description": "Base62 encoded cart id",
+        "schema": {
+          "type": "string",
+          "pattern": "^[0-9A-Za-z]+$",
+          "minLength": 1
+        }
+      },
+      "DeliveryIdParam": {
+        "name": "deliveryId",
+        "in": "path",
+        "required": true,
+        "schema": { "type": "integer", "format": "int64", "minimum": 0 }
+      },
+      "VoucherIdParam": {
+        "name": "voucherId",
+        "in": "path",
+        "required": true,
+        "schema": { "type": "integer", "format": "int64", "minimum": 0 }
+      }
+    },
+    "schemas": {
+      "CartGrain": {
+        "type": "object",
+        "description": "Cart aggregate (actor state)",
+        "properties": {
+          "id": {
+            "type": "string",
+            "description": "Cart id (base62 encoded uint64)"
+          },
+          "items": {
+            "type": "array",
+            "items": { "$ref": "#/components/schemas/CartItem" }
+          },
+          "totalPrice": { "type": "integer", "format": "int64" },
+          "totalTax": { "type": "integer", "format": "int64" },
+          "totalDiscount": { "type": "integer", "format": "int64" },
+          "deliveries": {
+            "type": "array",
+            "items": { "$ref": "#/components/schemas/CartDelivery" }
+          },
+          "processing": { "type": "boolean" },
+          "paymentInProgress": { "type": "boolean" },
+          "orderReference": { "type": "string" },
+          "paymentStatus": { "type": "string" },
+          "vouchers": {
+            "type": "array",
+            "items": { "$ref": "#/components/schemas/Voucher" }
+          },
+          "subscriptionDetails": {
+            "type": "object",
+            "additionalProperties": {
+              "$ref": "#/components/schemas/SubscriptionDetails"
+            }
+          }
+        },
+        "required": ["id", "items", "totalPrice", "totalTax", "totalDiscount"]
+      },
+      "CartItem": {
+        "type": "object",
+        "properties": {
+          "id": { "type": "integer" },
+          "itemId": { "type": "integer" },
+          "parentId": { "type": "integer" },
+          "sku": { "type": "string" },
+          "name": { "type": "string" },
+          "price": { "type": "integer", "format": "int64" },
+          "totalPrice": { "type": "integer", "format": "int64" },
+          "totalTax": { "type": "integer", "format": "int64" },
+          "orgPrice": { "type": "integer", "format": "int64" },
+          "stock": {
+            "type": "integer",
+            "description": "0=OutOfStock,1=LowStock,2=InStock"
+          },
+          "qty": { "type": "integer" },
+          "tax": { "type": "integer" },
+          "taxRate": { "type": "integer" },
+          "brand": { "type": "string" },
+          "category": { "type": "string" },
+          "category2": { "type": "string" },
+          "category3": { "type": "string" },
+          "category4": { "type": "string" },
+          "category5": { "type": "string" },
+          "disclaimer": { "type": "string" },
+          "sellerId": { "type": "string" },
+          "sellerName": { "type": "string" },
+          "type": { "type": "string", "description": "Article type" },
+          "image": { "type": "string" },
+          "outlet": { "type": "string", "nullable": true },
+          "storeId": { "type": "string", "nullable": true }
+        },
+        "required": ["id", "sku", "name", "price", "qty", "tax"]
+      },
+      "CartDelivery": {
+        "type": "object",
+        "properties": {
+          "id": { "type": "integer" },
+          "provider": { "type": "string" },
+          "price": { "type": "integer", "format": "int64" },
+          "items": {
+            "type": "array",
+            "items": { "type": "integer" }
+          },
+          "pickupPoint": { "$ref": "#/components/schemas/PickupPoint" }
+        },
+        "required": ["id", "provider", "price", "items"]
+      },
+      "PickupPoint": {
+        "type": "object",
+        "properties": {
+          "id": { "type": "string" },
+          "name": { "type": "string", "nullable": true },
+          "address": { "type": "string", "nullable": true },
+          "city": { "type": "string", "nullable": true },
+          "zip": { "type": "string", "nullable": true },
+          "country": { "type": "string", "nullable": true }
+        },
+        "required": ["id"]
+      },
+      "AddRequest": {
+        "type": "object",
+        "properties": {
+          "quantity": {
+            "type": "integer",
+            "format": "int32",
+            "minimum": 1,
+            "default": 1
+          },
+          "sku": { "type": "string" },
+          "country": {
+            "type": "string",
+            "description": "Two-letter country code (inferred if omitted)"
+          },
+          "storeId": { "type": "string", "nullable": true }
+        },
+        "required": ["sku"]
+      },
+      "ChangeQuantity": {
+        "type": "object",
+        "properties": {
+          "id": {
+            "type": "integer",
+            "format": "int64",
+            "description": "Cart line item id"
+          },
+          "quantity": { "type": "integer", "format": "int32", "minimum": 0 }
+        },
+        "required": ["id", "quantity"]
+      },
+      "Item": {
+        "type": "object",
+        "properties": {
+          "sku": { "type": "string" },
+          "quantity": { "type": "integer", "minimum": 1 },
+          "storeId": { "type": "string", "nullable": true }
+        },
+        "required": ["sku", "quantity"]
+      },
+      "SetCartItems": {
+        "type": "object",
+        "properties": {
+          "country": { "type": "string" },
+          "items": {
+            "type": "array",
+            "items": { "$ref": "#/components/schemas/Item" },
+            "minItems": 0
+          }
+        },
+        "required": ["items"]
+      },
+      "SetDeliveryRequest": {
+        "type": "object",
+        "properties": {
+          "provider": { "type": "string" },
+          "items": {
+            "type": "array",
+            "items": { "type": "integer", "format": "int64" },
+            "description": "Line item ids served by this delivery"
+          },
+          "pickupPoint": { "$ref": "#/components/schemas/PickupPoint" }
+        },
+        "required": ["provider", "items"]
+      },
+      "AddVoucherRequest": {
+        "type": "object",
+        "properties": {
+          "code": { "type": "string" }
+        },
+        "required": ["code"]
+      },
+      "UpsertSubscriptionDetails": {
+        "type": "object",
+        "properties": {
+          "id": { "type": "string" },
+          "offeringCode": { "type": "string" },
+          "signingType": { "type": "string" },
+          "data": { "type": "object" }
+        },
+        "required": ["offeringCode", "signingType"]
+      },
+      "Voucher": {
+        "type": "object",
+        "properties": {
+          "code": { "type": "string" },
+          "applied": { "type": "boolean" },
+          "rules": {
+            "type": "array",
+            "items": { "type": "string" }
+          },
+          "description": { "type": "string" },
+          "id": { "type": "integer", "format": "int64" },
+          "value": { "type": "integer", "format": "int64" }
+        },
+        "required": ["code", "applied", "rules", "id", "value"]
+      },
+      "SubscriptionDetails": {
+        "type": "object",
+        "properties": {
+          "id": { "type": "string" },
+          "offeringCode": { "type": "string" },
+          "signingType": { "type": "string" },
+          "data": { "type": "object" }
+        },
+        "required": ["id"]
+      }
+    }
+  },
+  "tags": [{ "name": "Cart" }, { "name": "Delivery" }, { "name": "System" }]
+}

cmd/cart/openapi_embed.go

@@ -0,0 +1,69 @@
+package main
+
+import (
+	"bytes"
+	"crypto/sha256"
+	_ "embed"
+	"encoding/hex"
+	"net/http"
+	"sync"
+)
+
+// openapi_embed.go: Provides embedded OpenAPI spec and helper to mount handler.
+
+//go:embed openapi.json
+var openapiJSON []byte
+
+var (
+	openapiOnce sync.Once
+	openapiETag string
+)
+
+// initOpenAPIMetadata computes immutable metadata for the embedded spec.
+func initOpenAPIMetadata() {
+	sum := sha256.Sum256(openapiJSON)
+	openapiETag = `W/"` + hex.EncodeToString(sum[:8]) + `"` // weak ETag with first 8 bytes
+}
+
+// ServeEmbeddedOpenAPI serves the embedded OpenAPI JSON spec at /openapi.json.
+// It supports GET and HEAD and implements basic ETag caching.
+func ServeEmbeddedOpenAPI(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodGet && r.Method != http.MethodHead {
+		w.Header().Set("Allow", "GET, HEAD")
+		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
+		return
+	}
+
+	openapiOnce.Do(initOpenAPIMetadata)
+
+	w.Header().Set("Content-Type", "application/json; charset=utf-8")
+	w.Header().Set("Cache-Control", "no-cache")
+	w.Header().Set("Access-Control-Allow-Origin", "*")
+	w.Header().Set("ETag", openapiETag)
+
+	if match := r.Header.Get("If-None-Match"); match != "" {
+		if bytes.Contains([]byte(match), []byte(openapiETag)) {
+			w.WriteHeader(http.StatusNotModified)
+			return
+		}
+	}
+
+	if r.Method == http.MethodHead {
+		w.WriteHeader(http.StatusOK)
+		return
+	}
+
+	w.WriteHeader(http.StatusOK)
+	_, _ = w.Write(openapiJSON)
+}
+
+// Optional: function to access raw spec bytes programmatically.
+func OpenAPISpecBytes() []byte {
+	return openapiJSON
+}
+
+// Optional: function to access current ETag.
+func OpenAPIETag() string {
+	openapiOnce.Do(initOpenAPIMetadata)
+	return openapiETag
+}

cmd/cart/otel.go

@@ -0,0 +1,117 @@
+package main
+
+import (
+	"context"
+	"errors"
+	"time"
+
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploggrpc"
+	"go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc"
+	"go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc"
+	"go.opentelemetry.io/otel/log/global"
+	"go.opentelemetry.io/otel/propagation"
+	"go.opentelemetry.io/otel/sdk/log"
+	"go.opentelemetry.io/otel/sdk/metric"
+	"go.opentelemetry.io/otel/sdk/trace"
+)
+
+// setupOTelSDK bootstraps the OpenTelemetry pipeline.
+// If it does not return an error, make sure to call shutdown for proper cleanup.
+func setupOTelSDK(ctx context.Context) (func(context.Context) error, error) {
+	var shutdownFuncs []func(context.Context) error
+	var err error
+
+	// shutdown calls cleanup functions registered via shutdownFuncs.
+	// The errors from the calls are joined.
+	// Each registered cleanup will be invoked once.
+	shutdown := func(ctx context.Context) error {
+		var err error
+		for _, fn := range shutdownFuncs {
+			err = errors.Join(err, fn(ctx))
+		}
+		shutdownFuncs = nil
+		return err
+	}
+
+	// handleErr calls shutdown for cleanup and makes sure that all errors are returned.
+	handleErr := func(inErr error) {
+		err = errors.Join(inErr, shutdown(ctx))
+	}
+
+	// Set up propagator.
+	prop := newPropagator()
+	otel.SetTextMapPropagator(prop)
+
+	// Set up trace provider.
+	tracerProvider, err := newTracerProvider()
+	if err != nil {
+		handleErr(err)
+		return shutdown, err
+	}
+	shutdownFuncs = append(shutdownFuncs, tracerProvider.Shutdown)
+	otel.SetTracerProvider(tracerProvider)
+
+	// Set up meter provider.
+	meterProvider, err := newMeterProvider()
+	if err != nil {
+		handleErr(err)
+		return shutdown, err
+	}
+	shutdownFuncs = append(shutdownFuncs, meterProvider.Shutdown)
+	otel.SetMeterProvider(meterProvider)
+
+	// Set up logger provider.
+	loggerProvider, err := newLoggerProvider()
+	if err != nil {
+		handleErr(err)
+		return shutdown, err
+	}
+	shutdownFuncs = append(shutdownFuncs, loggerProvider.Shutdown)
+	global.SetLoggerProvider(loggerProvider)
+
+	return shutdown, err
+}
+
+func newPropagator() propagation.TextMapPropagator {
+	return propagation.NewCompositeTextMapPropagator(
+		propagation.TraceContext{},
+		propagation.Baggage{},
+	)
+}
+
+func newTracerProvider() (*trace.TracerProvider, error) {
+	traceExporter, err := otlptracegrpc.New(context.Background())
+	if err != nil {
+		return nil, err
+	}
+
+	tracerProvider := trace.NewTracerProvider(
+		trace.WithBatcher(traceExporter,
+			// Default is 5s. Set to 1s for demonstrative purposes.
+			trace.WithBatchTimeout(time.Second)),
+	)
+	return tracerProvider, nil
+}
+
+func newMeterProvider() (*metric.MeterProvider, error) {
+	exporter, err := otlpmetricgrpc.New(context.Background())
+	if err != nil {
+		return nil, err
+	}
+
+	provider := metric.NewMeterProvider(metric.WithReader(metric.NewPeriodicReader(exporter)))
+	return provider, nil
+}
+
+func newLoggerProvider() (*log.LoggerProvider, error) {
+	logExporter, err := otlploggrpc.New(context.Background())
+	if err != nil {
+		return nil, err
+	}
+
+	loggerProvider := log.NewLoggerProvider(
+		log.WithProcessor(log.NewBatchProcessor(logExporter)),
+	)
+	return loggerProvider, nil
+}

cmd/cart/pool-server.go

@@ -0,0 +1,699 @@
+package main
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"log"
+	"net/http"
+	"strconv"
+	"sync"
+	"time"
+
+	"git.tornberg.me/go-cart-actor/pkg/actor"
+	"git.tornberg.me/go-cart-actor/pkg/cart"
+	messages "git.tornberg.me/go-cart-actor/pkg/messages"
+	"git.tornberg.me/go-cart-actor/pkg/voucher"
+	"git.tornberg.me/mats/go-redis-inventory/pkg/inventory"
+	"github.com/gogo/protobuf/proto"
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promauto"
+	"go.opentelemetry.io/contrib/bridges/otelslog"
+	"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
+	"google.golang.org/protobuf/types/known/anypb"
+
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/metric"
+	"go.opentelemetry.io/otel/trace"
+)
+
+var (
+	grainMutations = promauto.NewCounter(prometheus.CounterOpts{
+		Name: "cart_grain_mutations_total",
+		Help: "The total number of mutations",
+	})
+	grainLookups = promauto.NewCounter(prometheus.CounterOpts{
+		Name: "cart_grain_lookups_total",
+		Help: "The total number of lookups",
+	})
+)
+
+type PoolServer struct {
+	actor.GrainPool[*cart.CartGrain]
+	pod_name         string
+	klarnaClient     *KlarnaClient
+	inventoryService inventory.InventoryService
+}
+
+func NewPoolServer(pool actor.GrainPool[*cart.CartGrain], pod_name string, klarnaClient *KlarnaClient, inventoryService inventory.InventoryService) *PoolServer {
+	return &PoolServer{
+		GrainPool:        pool,
+		pod_name:         pod_name,
+		klarnaClient:     klarnaClient,
+		inventoryService: inventoryService,
+	}
+}
+
+func (s *PoolServer) ApplyLocal(ctx context.Context, id cart.CartId, mutation ...proto.Message) (*actor.MutationResult[*cart.CartGrain], error) {
+	return s.Apply(ctx, uint64(id), mutation...)
+}
+
+func (s *PoolServer) GetCartHandler(w http.ResponseWriter, r *http.Request, id cart.CartId) error {
+	grain, err := s.Get(r.Context(), uint64(id))
+	if err != nil {
+		return err
+	}
+
+	return s.WriteResult(w, grain)
+}
+
+func (s *PoolServer) AddSkuToCartHandler(w http.ResponseWriter, r *http.Request, id cart.CartId) error {
+	sku := r.PathValue("sku")
+	msg, err := GetItemAddMessage(r.Context(), sku, 1, getCountryFromHost(r.Host), nil)
+	if err != nil {
+		return err
+	}
+	data, err := s.ApplyLocal(r.Context(), id, msg)
+	if err != nil {
+		return err
+	}
+	grainMutations.Add(float64(len(data.Mutations)))
+	return s.WriteResult(w, data)
+}
+
+func (s *PoolServer) WriteResult(w http.ResponseWriter, result any) error {
+	w.Header().Set("Content-Type", "application/json")
+	w.Header().Set("Cache-Control", "no-cache")
+	w.Header().Set("Access-Control-Allow-Origin", "*")
+	w.Header().Set("X-Pod-Name", s.pod_name)
+	if result == nil {
+
+		w.WriteHeader(http.StatusInternalServerError)
+
+		return nil
+	}
+	w.WriteHeader(http.StatusOK)
+	enc := json.NewEncoder(w)
+	err := enc.Encode(result)
+	return err
+}
+
+func (s *PoolServer) DeleteItemHandler(w http.ResponseWriter, r *http.Request, id cart.CartId) error {
+
+	itemIdString := r.PathValue("itemId")
+	itemId, err := strconv.ParseInt(itemIdString, 10, 64)
+	if err != nil {
+		return err
+	}
+	data, err := s.ApplyLocal(r.Context(), id, &messages.RemoveItem{Id: uint32(itemId)})
+	if err != nil {
+		return err
+	}
+	return s.WriteResult(w, data)
+}
+
+type SetDeliveryRequest struct {
+	Provider    string                `json:"provider"`
+	Items       []uint32              `json:"items"`
+	PickupPoint *messages.PickupPoint `json:"pickupPoint,omitempty"`
+}
+
+func (s *PoolServer) SetDeliveryHandler(w http.ResponseWriter, r *http.Request, id cart.CartId) error {
+
+	delivery := SetDeliveryRequest{}
+	err := json.NewDecoder(r.Body).Decode(&delivery)
+	if err != nil {
+		return err
+	}
+	data, err := s.ApplyLocal(r.Context(), id, &messages.SetDelivery{
+		Provider:    delivery.Provider,
+		Items:       delivery.Items,
+		PickupPoint: delivery.PickupPoint,
+	})
+	if err != nil {
+		return err
+	}
+	return s.WriteResult(w, data)
+}
+
+func (s *PoolServer) SetPickupPointHandler(w http.ResponseWriter, r *http.Request, id cart.CartId) error {
+
+	deliveryIdString := r.PathValue("deliveryId")
+	deliveryId, err := strconv.ParseInt(deliveryIdString, 10, 64)
+	if err != nil {
+		return err
+	}
+	pickupPoint := messages.PickupPoint{}
+	err = json.NewDecoder(r.Body).Decode(&pickupPoint)
+	if err != nil {
+		return err
+	}
+	reply, err := s.ApplyLocal(r.Context(), id, &messages.SetPickupPoint{
+		DeliveryId: uint32(deliveryId),
+		Id:         pickupPoint.Id,
+		Name:       pickupPoint.Name,
+		Address:    pickupPoint.Address,
+		City:       pickupPoint.City,
+		Zip:        pickupPoint.Zip,
+		Country:    pickupPoint.Country,
+	})
+	if err != nil {
+		return err
+	}
+	return s.WriteResult(w, reply)
+}
+
+func (s *PoolServer) RemoveDeliveryHandler(w http.ResponseWriter, r *http.Request, id cart.CartId) error {
+
+	deliveryIdString := r.PathValue("deliveryId")
+	deliveryId, err := strconv.Atoi(deliveryIdString)
+	if err != nil {
+		return err
+	}
+	reply, err := s.ApplyLocal(r.Context(), id, &messages.RemoveDelivery{Id: uint32(deliveryId)})
+	if err != nil {
+		return err
+	}
+	return s.WriteResult(w, reply)
+}
+
+func (s *PoolServer) QuantityChangeHandler(w http.ResponseWriter, r *http.Request, id cart.CartId) error {
+	changeQuantity := messages.ChangeQuantity{}
+	err := json.NewDecoder(r.Body).Decode(&changeQuantity)
+	if err != nil {
+		return err
+	}
+	reply, err := s.ApplyLocal(r.Context(), id, &changeQuantity)
+	if err != nil {
+		return err
+	}
+	return s.WriteResult(w, reply)
+}
+
+type Item struct {
+	Sku      string  `json:"sku"`
+	Quantity int     `json:"quantity"`
+	StoreId  *string `json:"storeId,omitempty"`
+}
+
+type SetCartItems struct {
+	Country string `json:"country"`
+	Items   []Item `json:"items"`
+}
+
+func getMultipleAddMessages(ctx context.Context, items []Item, country string) []proto.Message {
+	wg := sync.WaitGroup{}
+	mu := sync.Mutex{}
+	msgs := make([]proto.Message, 0, len(items))
+	for _, itm := range items {
+		wg.Go(
+			func() {
+				msg, err := GetItemAddMessage(ctx, itm.Sku, itm.Quantity, country, itm.StoreId)
+				if err != nil {
+					log.Printf("error adding item %s: %v", itm.Sku, err)
+					return
+				}
+				mu.Lock()
+				msgs = append(msgs, msg)
+				mu.Unlock()
+			})
+	}
+	wg.Wait()
+	return msgs
+}
+
+func (s *PoolServer) SetCartItemsHandler(w http.ResponseWriter, r *http.Request, id cart.CartId) error {
+	setCartItems := SetCartItems{}
+	err := json.NewDecoder(r.Body).Decode(&setCartItems)
+	if err != nil {
+		return err
+	}
+
+	msgs := make([]proto.Message, 0, len(setCartItems.Items)+1)
+	msgs = append(msgs, &messages.ClearCartRequest{})
+	msgs = append(msgs, getMultipleAddMessages(r.Context(), setCartItems.Items, setCartItems.Country)...)
+
+	reply, err := s.ApplyLocal(r.Context(), id, msgs...)
+	if err != nil {
+		return err
+	}
+	return s.WriteResult(w, reply)
+}
+
+func (s *PoolServer) AddMultipleItemHandler(w http.ResponseWriter, r *http.Request, id cart.CartId) error {
+	setCartItems := SetCartItems{}
+	err := json.NewDecoder(r.Body).Decode(&setCartItems)
+	if err != nil {
+		return err
+	}
+
+	reply, err := s.ApplyLocal(r.Context(), id, getMultipleAddMessages(r.Context(), setCartItems.Items, setCartItems.Country)...)
+	if err != nil {
+		return err
+	}
+	return s.WriteResult(w, reply)
+}
+
+type AddRequest struct {
+	Sku      string  `json:"sku"`
+	Quantity int32   `json:"quantity"`
+	Country  string  `json:"country"`
+	StoreId  *string `json:"storeId"`
+}
+
+func (s *PoolServer) AddSkuRequestHandler(w http.ResponseWriter, r *http.Request, id cart.CartId) error {
+	addRequest := AddRequest{Quantity: 1}
+	err := json.NewDecoder(r.Body).Decode(&addRequest)
+	if err != nil {
+		return err
+	}
+	msg, err := GetItemAddMessage(r.Context(), addRequest.Sku, int(addRequest.Quantity), addRequest.Country, addRequest.StoreId)
+	if err != nil {
+		return err
+	}
+	reply, err := s.ApplyLocal(r.Context(), id, msg)
+	if err != nil {
+		return err
+	}
+
+	return s.WriteResult(w, reply)
+}
+
+// func (s *PoolServer) HandleConfirmation(w http.ResponseWriter, r *http.Request, id CartId) error {
+// 	orderId := r.PathValue("orderId")
+// 	if orderId == "" {
+// 		return fmt.Errorf("orderId is empty")
+// 	}
+// 	order, err := KlarnaInstance.GetOrder(orderId)
+
+// 	if err != nil {
+// 		return err
+// 	}
+
+// 	w.Header().Set("Content-Type", "application/json")
+// 	w.Header().Set("X-Pod-Name", s.pod_name)
+// 	w.Header().Set("Cache-Control", "no-cache")
+// 	w.Header().Set("Access-Control-Allow-Origin", "*")
+// 	w.WriteHeader(http.StatusOK)
+// 	return json.NewEncoder(w).Encode(order)
+// }
+
+func getCurrency(country string) string {
+	if country == "no" {
+		return "NOK"
+	}
+	return "SEK"
+}
+
+func getLocale(country string) string {
+	if country == "no" {
+		return "nb-no"
+	}
+	return "sv-se"
+}
+
+func getLocationId(item *cart.CartItem) inventory.LocationID {
+	if item.StoreId == nil || *item.StoreId == "" {
+		return "se"
+	}
+	return inventory.LocationID(*item.StoreId)
+}
+
+func getInventoryRequests(items []*cart.CartItem) []inventory.ReserveRequest {
+	var requests []inventory.ReserveRequest
+	for _, item := range items {
+		if item == nil {
+			continue
+		}
+		requests = append(requests, inventory.ReserveRequest{
+			SKU:        inventory.SKU(item.Sku),
+			LocationID: getLocationId(item),
+			Quantity:   uint32(item.Quantity),
+		})
+	}
+	return requests
+}
+
+func getOriginalHost(r *http.Request) string {
+	proxyHost := r.Header.Get("X-Forwarded-Host")
+	if proxyHost != "" {
+		return proxyHost
+	}
+	return r.Host
+}
+
+func (s *PoolServer) CreateOrUpdateCheckout(r *http.Request, id cart.CartId) (*CheckoutOrder, error) {
+	host := getOriginalHost(r)
+	country := getCountryFromHost(host)
+	meta := &CheckoutMeta{
+		Terms:        fmt.Sprintf("https://%s/terms", host),
+		Checkout:     fmt.Sprintf("https://%s/checkout?order_id={checkout.order.id}", host),
+		Confirmation: fmt.Sprintf("https://%s/confirmation/{checkout.order.id}", host),
+		Country:      country,
+		Currency:     getCurrency(country),
+		Locale:       getLocale(country),
+	}
+
+	// Get current grain state (may be local or remote)
+	grain, err := s.Get(r.Context(), uint64(id))
+	if err != nil {
+		return nil, err
+	}
+	if s.inventoryService != nil {
+		inventoryRequests := getInventoryRequests(grain.Items)
+		failingRequest, err := s.inventoryService.ReservationCheck(r.Context(), inventoryRequests...)
+		if err != nil {
+			logger.WarnContext(r.Context(), "inventory check failed", string(failingRequest.SKU), string(failingRequest.LocationID))
+			return nil, err
+		}
+	}
+
+	// Build pure checkout payload
+	payload, _, err := BuildCheckoutOrderPayload(grain, meta)
+	if err != nil {
+		return nil, err
+	}
+
+	if grain.OrderReference != "" {
+		return s.klarnaClient.UpdateOrder(r.Context(), grain.OrderReference, bytes.NewReader(payload))
+	} else {
+		return s.klarnaClient.CreateOrder(r.Context(), bytes.NewReader(payload))
+	}
+}
+
+func (s *PoolServer) ApplyCheckoutStarted(ctx context.Context, klarnaOrder *CheckoutOrder, id cart.CartId) (*actor.MutationResult[*cart.CartGrain], error) {
+	// Persist initialization state via mutation (best-effort)
+	return s.ApplyLocal(ctx, id, &messages.InitializeCheckout{
+		OrderId:           klarnaOrder.ID,
+		Status:            klarnaOrder.Status,
+		PaymentInProgress: true,
+	})
+}
+
+// func (s *PoolServer) HandleCheckout(w http.ResponseWriter, r *http.Request, id CartId) error {
+// 	klarnaOrder, err := s.CreateOrUpdateCheckout(r.Host, id)
+// 	if err != nil {
+// 		return err
+// 	}
+
+// 	s.ApplyCheckoutStarted(klarnaOrder, id)
+
+// 	w.Header().Set("Content-Type", "application/json")
+// 	return json.NewEncoder(w).Encode(klarnaOrder)
+// }
+//
+
+func CookieCartIdHandler(fn func(cartId cart.CartId, w http.ResponseWriter, r *http.Request) error) func(w http.ResponseWriter, r *http.Request) {
+	return func(w http.ResponseWriter, r *http.Request) {
+		var id cart.CartId
+		cookie, err := r.Cookie("cartid")
+		if err != nil || cookie.Value == "" {
+			id = cart.MustNewCartId()
+			http.SetCookie(w, &http.Cookie{
+				Name:     "cartid",
+				Value:    id.String(),
+				Secure:   r.TLS != nil,
+				HttpOnly: true,
+				Path:     "/",
+				Expires:  time.Now().AddDate(0, 0, 14),
+				SameSite: http.SameSiteLaxMode,
+			})
+			w.Header().Set("Set-Cart-Id", id.String())
+		} else {
+			parsed, ok := cart.ParseCartId(cookie.Value)
+			if !ok {
+				id = cart.MustNewCartId()
+				http.SetCookie(w, &http.Cookie{
+					Name:     "cartid",
+					Value:    id.String(),
+					Secure:   r.TLS != nil,
+					HttpOnly: true,
+					Path:     "/",
+					Expires:  time.Now().AddDate(0, 0, 14),
+					SameSite: http.SameSiteLaxMode,
+				})
+				w.Header().Set("Set-Cart-Id", id.String())
+			} else {
+				id = parsed
+			}
+		}
+
+		err = fn(id, w, r)
+		if err != nil {
+			log.Printf("Server error, not remote error: %v\n", err)
+			w.WriteHeader(http.StatusInternalServerError)
+			w.Write([]byte(err.Error()))
+		}
+
+	}
+}
+
+// Removed leftover legacy block after CookieCartIdHandler (obsolete code referencing cid/legacy)
+
+func (s *PoolServer) RemoveCartCookie(w http.ResponseWriter, r *http.Request, cartId cart.CartId) error {
+	// Clear cart cookie (breaking change: do not issue a new legacy id here)
+	http.SetCookie(w, &http.Cookie{
+		Name:     "cartid",
+		Value:    "",
+		Path:     "/",
+		Secure:   r.TLS != nil,
+		HttpOnly: true,
+		Expires:  time.Unix(0, 0),
+		SameSite: http.SameSiteLaxMode,
+	})
+	w.WriteHeader(http.StatusOK)
+	return nil
+}
+
+func CartIdHandler(fn func(cartId cart.CartId, w http.ResponseWriter, r *http.Request) error) func(w http.ResponseWriter, r *http.Request) {
+	return func(w http.ResponseWriter, r *http.Request) {
+		var id cart.CartId
+		raw := r.PathValue("id")
+		// If no id supplied, generate a new one
+		if raw == "" {
+			id := cart.MustNewCartId()
+			w.Header().Set("Set-Cart-Id", id.String())
+		} else {
+			// Parse base62 cart id
+			if parsedId, ok := cart.ParseCartId(raw); !ok {
+				w.WriteHeader(http.StatusBadRequest)
+				w.Write([]byte("cart id is invalid"))
+				return
+			} else {
+				id = parsedId
+			}
+		}
+
+		err := fn(id, w, r)
+		if err != nil {
+			log.Printf("Server error, not remote error: %v\n", err)
+			w.WriteHeader(http.StatusInternalServerError)
+			w.Write([]byte(err.Error()))
+		}
+	}
+}
+
+func (s *PoolServer) ProxyHandler(fn func(w http.ResponseWriter, r *http.Request, cartId cart.CartId) error) func(cartId cart.CartId, w http.ResponseWriter, r *http.Request) error {
+	return func(cartId cart.CartId, w http.ResponseWriter, r *http.Request) error {
+		if ownerHost, ok := s.OwnerHost(uint64(cartId)); ok {
+			ctx, span := tracer.Start(r.Context(), "proxy")
+			defer span.End()
+			span.SetAttributes(attribute.String("cartid", cartId.String()))
+			hostAttr := attribute.String("other host", ownerHost.Name())
+			span.SetAttributes(hostAttr)
+			logger.InfoContext(ctx, "cart proxyed", "result", ownerHost.Name())
+			proxyCalls.Add(ctx, 1, metric.WithAttributes(hostAttr))
+			handled, err := ownerHost.Proxy(uint64(cartId), w, r)
+
+			grainLookups.Inc()
+			if err == nil && handled {
+				return nil
+			}
+		}
+		_, span := tracer.Start(r.Context(), "own")
+		span.SetAttributes(attribute.String("cartid", cartId.String()))
+		defer span.End()
+		return fn(w, r, cartId)
+
+	}
+}
+
+var (
+	tracer = otel.Tracer(name)
+
+	meter      = otel.Meter(name)
+	logger     = otelslog.NewLogger(name)
+	proxyCalls metric.Int64Counter
+
+// rollCnt metric.Int64Counter
+)
+
+func init() {
+	var err error
+	proxyCalls, err = meter.Int64Counter("proxy.calls",
+		metric.WithDescription("Number of proxy calls"),
+		metric.WithUnit("{calls}"))
+	if err != nil {
+		panic(err)
+	}
+
+}
+
+type AddVoucherRequest struct {
+	VoucherCode string `json:"code"`
+}
+
+func (s *PoolServer) AddVoucherHandler(w http.ResponseWriter, r *http.Request, cartId cart.CartId) error {
+	data := &AddVoucherRequest{}
+	json.NewDecoder(r.Body).Decode(data)
+	v := voucher.Service{}
+	msg, err := v.GetVoucher(data.VoucherCode)
+	if err != nil {
+		s.ApplyLocal(r.Context(), cartId, &messages.PreConditionFailed{
+			Operation: "AddVoucher",
+			Error:     err.Error(),
+		})
+		w.WriteHeader(http.StatusInternalServerError)
+		w.Write([]byte(err.Error()))
+		return err
+	}
+	reply, err := s.ApplyLocal(r.Context(), cartId, msg)
+	if err != nil {
+		w.WriteHeader(http.StatusInternalServerError)
+		w.Write([]byte(err.Error()))
+		return err
+	}
+	s.WriteResult(w, reply)
+	return nil
+}
+
+type SubscriptionDetailsRequest struct {
+	Id           *string         `json:"id,omitempty"`
+	OfferingCode string          `json:"offeringCode,omitempty"`
+	SigningType  string          `json:"signingType,omitempty"`
+	Data         json.RawMessage `json:"data,omitempty"`
+}
+
+func (sd *SubscriptionDetailsRequest) ToMessage() *messages.UpsertSubscriptionDetails {
+	return &messages.UpsertSubscriptionDetails{
+		Id:           sd.Id,
+		OfferingCode: sd.OfferingCode,
+		SigningType:  sd.SigningType,
+		Data:         &anypb.Any{Value: sd.Data},
+	}
+}
+
+func (s *PoolServer) SubscriptionDetailsHandler(w http.ResponseWriter, r *http.Request, cartId cart.CartId) error {
+	data := &SubscriptionDetailsRequest{}
+	err := json.NewDecoder(r.Body).Decode(data)
+	if err != nil {
+		w.WriteHeader(http.StatusInternalServerError)
+		w.Write([]byte(err.Error()))
+		return err
+	}
+	reply, err := s.ApplyLocal(r.Context(), cartId, data.ToMessage())
+	if err != nil {
+		w.WriteHeader(http.StatusInternalServerError)
+		w.Write([]byte(err.Error()))
+		return err
+	}
+	s.WriteResult(w, reply)
+	return nil
+}
+
+func (s *PoolServer) CheckoutHandler(fn func(order *CheckoutOrder, w http.ResponseWriter) error) func(w http.ResponseWriter, r *http.Request) {
+	return CookieCartIdHandler(s.ProxyHandler(func(w http.ResponseWriter, r *http.Request, cartId cart.CartId) error {
+		orderId := r.URL.Query().Get("order_id")
+		if orderId == "" {
+			order, err := s.CreateOrUpdateCheckout(r, cartId)
+			if err != nil {
+				logger.Error("unable to create klarna session", "error", err)
+				return err
+			}
+			s.ApplyCheckoutStarted(r.Context(), order, cartId)
+			return fn(order, w)
+		}
+		order, err := s.klarnaClient.GetOrder(r.Context(), orderId)
+		if err != nil {
+			return err
+		}
+		return fn(order, w)
+	}))
+}
+
+func (s *PoolServer) RemoveVoucherHandler(w http.ResponseWriter, r *http.Request, cartId cart.CartId) error {
+
+	idStr := r.PathValue("voucherId")
+	id, err := strconv.ParseInt(idStr, 10, 64)
+	if err != nil {
+		w.WriteHeader(http.StatusInternalServerError)
+		w.Write([]byte(err.Error()))
+		return err
+	}
+	reply, err := s.ApplyLocal(r.Context(), cartId, &messages.RemoveVoucher{Id: uint32(id)})
+	if err != nil {
+		w.WriteHeader(http.StatusInternalServerError)
+		w.Write([]byte(err.Error()))
+		return err
+	}
+	s.WriteResult(w, reply)
+	return nil
+}
+
+func (s *PoolServer) Serve(mux *http.ServeMux) {
+
+	// mux.HandleFunc("OPTIONS /cart", func(w http.ResponseWriter, r *http.Request) {
+	// 	w.Header().Set("Access-Control-Allow-Origin", "*")
+	// 	w.Header().Set("Access-Control-Allow-Methods", "GET, PUT, POST, DELETE")
+	// 	w.Header().Set("Access-Control-Allow-Headers", "Content-Type")
+	// 	w.WriteHeader(http.StatusOK)
+	// })
+
+	handleFunc := func(pattern string, handlerFunc func(http.ResponseWriter, *http.Request)) {
+		attr := attribute.String("http.route", pattern)
+		mux.HandleFunc(pattern, http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			span := trace.SpanFromContext(r.Context())
+			span.SetName(pattern)
+			span.SetAttributes(attr)
+
+			labeler, _ := otelhttp.LabelerFromContext(r.Context())
+			labeler.Add(attr)
+
+			handlerFunc(w, r)
+		}))
+	}
+
+	handleFunc("GET /cart", CookieCartIdHandler(s.ProxyHandler(s.GetCartHandler)))
+	handleFunc("GET /cart/add/{sku}", CookieCartIdHandler(s.ProxyHandler(s.AddSkuToCartHandler)))
+	handleFunc("POST /cart/add", CookieCartIdHandler(s.ProxyHandler(s.AddMultipleItemHandler)))
+	handleFunc("POST /cart", CookieCartIdHandler(s.ProxyHandler(s.AddSkuRequestHandler)))
+	handleFunc("POST /cart/set", CookieCartIdHandler(s.ProxyHandler(s.SetCartItemsHandler)))
+	handleFunc("DELETE /cart/{itemId}", CookieCartIdHandler(s.ProxyHandler(s.DeleteItemHandler)))
+	handleFunc("PUT /cart", CookieCartIdHandler(s.ProxyHandler(s.QuantityChangeHandler)))
+	handleFunc("DELETE /cart", CookieCartIdHandler(s.ProxyHandler(s.RemoveCartCookie)))
+	handleFunc("POST /cart/delivery", CookieCartIdHandler(s.ProxyHandler(s.SetDeliveryHandler)))
+	handleFunc("DELETE /cart/delivery/{deliveryId}", CookieCartIdHandler(s.ProxyHandler(s.RemoveDeliveryHandler)))
+	handleFunc("PUT /cart/delivery/{deliveryId}/pickupPoint", CookieCartIdHandler(s.ProxyHandler(s.SetPickupPointHandler)))
+	handleFunc("PUT /cart/voucher", CookieCartIdHandler(s.ProxyHandler(s.AddVoucherHandler)))
+	handleFunc("PUT /cart/subscription-details", CookieCartIdHandler(s.ProxyHandler(s.SubscriptionDetailsHandler)))
+	handleFunc("DELETE /cart/voucher/{voucherId}", CookieCartIdHandler(s.ProxyHandler(s.RemoveVoucherHandler)))
+
+	//mux.HandleFunc("GET /cart/checkout", CookieCartIdHandler(s.ProxyHandler(s.HandleCheckout)))
+	//mux.HandleFunc("GET /cart/confirmation/{orderId}", CookieCartIdHandler(s.ProxyHandler(s.HandleConfirmation)))
+
+	handleFunc("GET /cart/byid/{id}", CartIdHandler(s.ProxyHandler(s.GetCartHandler)))
+	handleFunc("GET /cart/byid/{id}/add/{sku}", CartIdHandler(s.ProxyHandler(s.AddSkuToCartHandler)))
+	handleFunc("POST /cart/byid/{id}", CartIdHandler(s.ProxyHandler(s.AddSkuRequestHandler)))
+	handleFunc("DELETE /cart/byid/{id}/{itemId}", CartIdHandler(s.ProxyHandler(s.DeleteItemHandler)))
+	handleFunc("PUT /cart/byid/{id}", CartIdHandler(s.ProxyHandler(s.QuantityChangeHandler)))
+	handleFunc("POST /cart/byid/{id}/delivery", CartIdHandler(s.ProxyHandler(s.SetDeliveryHandler)))
+	handleFunc("DELETE /cart/byid/{id}/delivery/{deliveryId}", CartIdHandler(s.ProxyHandler(s.RemoveDeliveryHandler)))
+	handleFunc("PUT /cart/byid/{id}/delivery/{deliveryId}/pickupPoint", CartIdHandler(s.ProxyHandler(s.SetPickupPointHandler)))
+	handleFunc("PUT /cart/byid/{id}/voucher", CookieCartIdHandler(s.ProxyHandler(s.AddVoucherHandler)))
+	handleFunc("DELETE /cart/byid/{id}/voucher/{voucherId}", CookieCartIdHandler(s.ProxyHandler(s.RemoveVoucherHandler)))
+	//mux.HandleFunc("GET /cart/byid/{id}/checkout", CartIdHandler(s.ProxyHandler(s.HandleCheckout)))
+	//mux.HandleFunc("GET /cart/byid/{id}/confirmation", CartIdHandler(s.ProxyHandler(s.HandleConfirmation)))
+
+}

cmd/cart/product-fetcher.go

@@ -0,0 +1,146 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"net/http"
+
+	"git.tornberg.me/go-cart-actor/pkg/cart"
+	messages "git.tornberg.me/go-cart-actor/pkg/messages"
+	"github.com/matst80/slask-finder/pkg/index"
+)
+
+// TODO make this configurable
+func getBaseUrl(country string) string {
+	// if country == "se" {
+	// 	return "http://s10n-se:8080"
+	// }
+	if country == "no" {
+		return "http://s10n-no.s10n:8080"
+	}
+	if country == "se" {
+		return "http://s10n-se.s10n:8080"
+	}
+	return "http://localhost:8082"
+}
+
+func FetchItem(ctx context.Context, sku string, country string) (*index.DataItem, error) {
+	baseUrl := getBaseUrl(country)
+	req, err := http.NewRequest("GET", fmt.Sprintf("%s/api/by-sku/%s", baseUrl, sku), nil)
+	innerCtx, span := tracer.Start(ctx, fmt.Sprintf("fetching data for %s", sku))
+	defer span.End()
+	req = req.WithContext(innerCtx)
+	if err != nil {
+		return nil, err
+	}
+	res, err := http.DefaultClient.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer res.Body.Close()
+	var item index.DataItem
+	err = json.NewDecoder(res.Body).Decode(&item)
+	return &item, err
+}
+
+func GetItemAddMessage(ctx context.Context, sku string, qty int, country string, storeId *string) (*messages.AddItem, error) {
+	item, err := FetchItem(ctx, sku, country)
+	if err != nil {
+		return nil, err
+	}
+	return ToItemAddMessage(item, storeId, qty, country)
+}
+
+func ToItemAddMessage(item *index.DataItem, storeId *string, qty int, country string) (*messages.AddItem, error) {
+	orgPrice, _ := getInt(item.GetNumberFieldValue(5)) // getInt(item.Fields[5])
+
+	price, err := getInt(item.GetNumberFieldValue(4)) //Fields[4]
+	if err != nil {
+		return nil, err
+	}
+	stk := item.GetStock()
+	stock := cart.StockStatus(0)
+
+	if storeId == nil {
+		centralStock, ok := stk[country]
+		if ok {
+			if !item.Buyable {
+				return nil, fmt.Errorf("item not available")
+			}
+
+			if centralStock == 0 && item.SaleStatus == "TBD" {
+				return nil, fmt.Errorf("no items available")
+			}
+			stock = cart.StockStatus(centralStock)
+		}
+
+	} else {
+		if !item.BuyableInStore {
+			return nil, fmt.Errorf("item not available in store")
+		}
+		storeStock, ok := stk[*storeId]
+		if ok {
+			stock = cart.StockStatus(storeStock)
+		}
+
+	}
+
+	articleType, _ := item.GetStringFieldValue(1)   //.Fields[1].(string)
+	outletGrade, ok := item.GetStringFieldValue(20) //.Fields[20].(string)
+	var outlet *string
+	if ok {
+		outlet = &outletGrade
+	}
+	sellerId, _ := item.GetStringFieldValue(24)  // .Fields[24].(string)
+	sellerName, _ := item.GetStringFieldValue(9) // .Fields[9].(string)
+
+	brand, _ := item.GetStringFieldValue(2)      //.Fields[2].(string)
+	category, _ := item.GetStringFieldValue(10)  //.Fields[10].(string)
+	category2, _ := item.GetStringFieldValue(11) //.Fields[11].(string)
+	category3, _ := item.GetStringFieldValue(12) //.Fields[12].(string)
+	category4, _ := item.GetStringFieldValue(13) //Fields[13].(string)
+	category5, _ := item.GetStringFieldValue(14) //.Fields[14].(string)
+
+	return &messages.AddItem{
+		ItemId:      uint32(item.Id),
+		Quantity:    int32(qty),
+		Price:       int64(price),
+		OrgPrice:    int64(orgPrice),
+		Sku:         item.GetSku(),
+		Name:        item.Title,
+		Image:       item.Img,
+		Stock:       int32(stock),
+		Brand:       brand,
+		Category:    category,
+		Category2:   category2,
+		Category3:   category3,
+		Category4:   category4,
+		Category5:   category5,
+		Tax:         getTax(articleType),
+		SellerId:    sellerId,
+		SellerName:  sellerName,
+		ArticleType: articleType,
+		Disclaimer:  item.Disclaimer,
+		Country:     country,
+		Outlet:      outlet,
+		StoreId:     storeId,
+		SaleStatus:  item.SaleStatus,
+	}, nil
+}
+
+func getTax(articleType string) int32 {
+	switch articleType {
+	case "ZDIE":
+		return 600
+	default:
+		return 2500
+	}
+}
+
+func getInt(data float64, ok bool) (int, error) {
+	if !ok {
+		return 0, fmt.Errorf("invalid type")
+	}
+	return int(data), nil
+}

cmd/inventory/main.go

@@ -0,0 +1,143 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"log"
+	"net/http"
+	"os"
+	"strings"
+	"sync"
+
+	"git.tornberg.me/mats/go-redis-inventory/pkg/inventory"
+	"github.com/matst80/slask-finder/pkg/index"
+	"github.com/matst80/slask-finder/pkg/messaging"
+	"github.com/redis/go-redis/v9"
+	"github.com/redis/go-redis/v9/maintnotifications"
+
+	amqp "github.com/rabbitmq/amqp091-go"
+)
+
+type Server struct {
+	service *inventory.RedisInventoryService
+}
+
+func (srv *Server) livezHandler(w http.ResponseWriter, r *http.Request) {
+	w.WriteHeader(http.StatusOK)
+	w.Write([]byte("OK"))
+}
+
+func (srv *Server) readyzHandler(w http.ResponseWriter, r *http.Request) {
+	w.WriteHeader(http.StatusOK)
+	w.Write([]byte("OK"))
+}
+
+func (srv *Server) getInventoryHandler(w http.ResponseWriter, r *http.Request) {
+	// Parse path: /inventory/{sku}/{location}
+	path := r.URL.Path
+	parts := strings.Split(strings.Trim(path, "/"), "/")
+	if len(parts) != 3 || parts[0] != "inventory" {
+		http.Error(w, "Invalid path", http.StatusBadRequest)
+		return
+	}
+	sku := inventory.SKU(parts[1])
+	locationID := inventory.LocationID(parts[2])
+
+	quantity, err := srv.service.GetInventory(r.Context(), sku, locationID)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	response := map[string]int64{"quantity": quantity}
+	w.Header().Set("Content-Type", "application/json")
+	json.NewEncoder(w).Encode(response)
+}
+
+var country = "se"
+var redisAddress = "10.10.3.18:6379"
+var redisPassword = "slaskredis"
+
+func init() {
+	// Override redis config from environment variables if set
+	if addr, ok := os.LookupEnv("REDIS_ADDRESS"); ok {
+		redisAddress = addr
+	}
+	if password, ok := os.LookupEnv("REDIS_PASSWORD"); ok {
+		redisPassword = password
+	}
+	if ctry, ok := os.LookupEnv("COUNTRY"); ok {
+		country = ctry
+	}
+}
+
+func main() {
+	var ctx = context.Background()
+	rdb := redis.NewClient(&redis.Options{
+		Addr:     redisAddress,
+		Password: redisPassword, // no password set
+		DB:       0,             // use default DB
+		MaintNotificationsConfig: &maintnotifications.Config{
+			Mode: maintnotifications.ModeDisabled,
+		},
+	})
+	s, err := inventory.NewRedisInventoryService(rdb)
+	if err != nil {
+		log.Fatalf("Unable to connect to inventory redis: %v", err)
+		return
+	}
+
+	server := &Server{service: s}
+
+	// Set up HTTP routes
+	http.HandleFunc("/livez", server.livezHandler)
+	http.HandleFunc("/readyz", server.readyzHandler)
+	http.HandleFunc("/inventory/", server.getInventoryHandler)
+
+	stockhandler := &StockHandler{
+		MainStockLocationID: inventory.LocationID(country),
+		rdb:                 rdb,
+		ctx:                 ctx,
+		svc:                 *s,
+	}
+
+	amqpUrl, ok := os.LookupEnv("RABBIT_HOST")
+	if ok {
+		log.Printf("Connecting to rabbitmq")
+		conn, err := amqp.DialConfig(amqpUrl, amqp.Config{
+			Properties: amqp.NewConnectionProperties(),
+		})
+		//a.conn = conn
+		if err != nil {
+			log.Fatalf("Failed to connect to RabbitMQ: %v", err)
+		}
+		ch, err := conn.Channel()
+		if err != nil {
+			log.Fatalf("Failed to open a channel: %v", err)
+		}
+		// items listener
+		err = messaging.ListenToTopic(ch, country, "item_added", func(d amqp.Delivery) error {
+			var items []*index.DataItem
+			err := json.Unmarshal(d.Body, &items)
+			if err == nil {
+				log.Printf("Got upserts %d, message count %d", len(items), d.MessageCount)
+				wg := &sync.WaitGroup{}
+				for _, item := range items {
+					stockhandler.HandleItem(item, wg)
+				}
+				wg.Wait()
+				log.Print("Batch done...")
+			} else {
+				log.Printf("Failed to unmarshal upsert message %v", err)
+			}
+			return err
+		})
+		if err != nil {
+			log.Fatalf("Failed to listen to item_added topic: %v", err)
+		}
+	}
+
+	// Start HTTP server
+	log.Println("Starting HTTP server on :8080")
+	log.Fatal(http.ListenAndServe(":8080", nil))
+}

cmd/inventory/stockhandler.go

@@ -0,0 +1,49 @@
+package main
+
+import (
+	"context"
+	"log"
+	"strconv"
+	"strings"
+	"sync"
+
+	"git.tornberg.me/mats/go-redis-inventory/pkg/inventory"
+	"github.com/matst80/slask-finder/pkg/types"
+	"github.com/redis/go-redis/v9"
+)
+
+type StockHandler struct {
+	rdb                 *redis.Client
+	ctx                 context.Context
+	svc                 inventory.RedisInventoryService
+	MainStockLocationID inventory.LocationID
+}
+
+func (s *StockHandler) HandleItem(item types.Item, wg *sync.WaitGroup) {
+	wg.Go(func() {
+		ctx := s.ctx
+		pipe := s.rdb.Pipeline()
+		centralStockString, ok := item.GetStringFieldValue(3)
+		if !ok {
+			centralStockString = "0"
+		}
+		centralStockString = strings.Replace(centralStockString, "+", "", -1)
+		centralStockString = strings.Replace(centralStockString, "<", "", -1)
+		centralStockString = strings.Replace(centralStockString, ">", "", -1)
+		centralStock, err := strconv.ParseInt(centralStockString, 10, 64)
+
+		if err != nil {
+			log.Printf("unable to parse central stock for item %s: %v", item.GetSku(), err)
+			centralStock = 0
+		} else {
+			s.svc.UpdateInventory(ctx, pipe, inventory.SKU(item.GetSku()), s.MainStockLocationID, int64(centralStock))
+		}
+		for id, value := range item.GetStock() {
+			s.svc.UpdateInventory(ctx, pipe, inventory.SKU(item.GetSku()), inventory.LocationID(id), int64(value))
+		}
+		_, err = pipe.Exec(ctx)
+		if err != nil {
+			log.Printf("unable to update stock: %v", err)
+		}
+	})
+}

cookies.txt

@@ -0,0 +1,5 @@
+# Netscape HTTP Cookie File
+# https://curl.se/docs/http-cookies.html
+# This file was generated by libcurl! Edit at your own risk.
+
+#HttpOnly_localhost	FALSE	/	FALSE	1761304670	cartid	4393545184291837

deployment/deployment-no.yaml

@@ -1,276 +0,0 @@
-apiVersion: v1
-kind: Secret
-metadata:
-  name:  klarna-api-credentials
-data:
-  username: ZjQzZDY3YjEtNzA2Yy00NTk2LTliNTgtYjg1YjU2NDEwZTUw
-  password: a2xhcm5hX3Rlc3RfYXBpX0trUWhWVE5yYVZsV2FsTnhTRVp3Y1ZSSFF5UkVNRmxyY25Kd1AxSndQMGdzWmpRelpEWTNZakV0TnpBMll5MDBOVGsyTFRsaU5UZ3RZamcxWWpVMk5ERXdaVFV3TERFc2JUUkNjRFpWU1RsTllsSk1aMlEyVEc4MmRVODNZMkozUlRaaFdEZDViV3AwYkhGV1JqTjVNQzlaYXow
-type: Opaque
----
-apiVersion: apps/v1
-kind: Deployment
-metadata:
-  labels:
-    app: cart-actor
-    arch: amd64
-  name: cart-actor-x86
-spec:
-  replicas: 0
-  selector:
-    matchLabels:
-      app: cart-actor
-      arch: amd64
-  template:
-    metadata:
-      labels:
-        app: cart-actor
-        actor-pool: cart
-        arch: amd64
-    spec:
-      affinity:
-        nodeAffinity:
-          requiredDuringSchedulingIgnoredDuringExecution:
-            nodeSelectorTerms:
-              - matchExpressions:
-                - key: kubernetes.io/arch
-                  operator: NotIn
-                  values:
-                    - arm64
-      volumes:
-        - name: data
-          nfs:
-            path: /i-data/7a8af061/nfs/cart-actor-no
-            server: 10.10.1.10
-      imagePullSecrets:
-        - name: regcred
-      serviceAccountName: default
-      containers:
-        - image: registry.knatofs.se/go-cart-actor-amd64:latest
-          name: cart-actor-amd64
-          imagePullPolicy: Always
-          lifecycle:
-            preStop:
-              exec:
-                command: ["sleep", "15"]
-          ports:
-            - containerPort: 8080
-              name: web
-            - containerPort: 1234
-              name: echo
-            - containerPort: 1337
-              name: rpc
-            - containerPort: 1338
-              name: quorum
-          livenessProbe:
-            httpGet:
-              path: /livez
-              port: web
-            failureThreshold: 1
-            periodSeconds: 10
-          readinessProbe:
-            httpGet:
-              path: /readyz
-              port: web
-            failureThreshold: 2
-            initialDelaySeconds: 2
-            periodSeconds: 10
-          volumeMounts:
-            - mountPath: "/data"
-              name: data
-          resources:
-            limits:
-              memory: "768Mi"
-            requests:
-              memory: "70Mi"
-              cpu: "1200m"
-          env:
-            - name: TZ
-              value: "Europe/Stockholm"
-            - name: KLARNA_API_USERNAME
-              valueFrom:
-                secretKeyRef:
-                  name: klarna-api-credentials
-                  key: username
-            - name: KLARNA_API_PASSWORD
-              valueFrom:
-                secretKeyRef:
-                  name: klarna-api-credentials
-                  key: password
-            - name: POD_IP
-              valueFrom:
-                fieldRef:
-                  fieldPath: status.podIP
-            - name: AMQP_URL
-              value: "amqp://admin:12bananer@rabbitmq.dev:5672/"
-            - name: BASE_URL
-              value: "https://s10n-no.tornberg.me"
-            - name: CART_BASE_URL
-              value: "https://cart-no.tornberg.me"
-            - name: POD_NAME
-              valueFrom:
-                fieldRef:
-                  fieldPath: metadata.name
----
-apiVersion: apps/v1
-kind: Deployment
-metadata:
-  labels:
-    app: cart-actor
-    arch: arm64
-  name: cart-actor-arm64
-spec:
-  replicas: 3
-  selector:
-    matchLabels:
-      app: cart-actor
-      arch: arm64
-  template:
-    metadata:
-      labels:
-        app: cart-actor
-        actor-pool: cart
-        arch: arm64
-    spec:
-      affinity:
-        nodeAffinity:
-          requiredDuringSchedulingIgnoredDuringExecution:
-            nodeSelectorTerms:
-              - matchExpressions:
-                - key: kubernetes.io/hostname
-                  operator: NotIn
-                  values:
-                    - masterpi
-                - key: kubernetes.io/arch
-                  operator: In
-                  values:
-                    - arm64
-      volumes:
-        - name: data
-          nfs:
-            path: /i-data/7a8af061/nfs/cart-actor-no
-            server: 10.10.1.10
-      imagePullSecrets:
-        - name: regcred
-      serviceAccountName: default
-      containers:
-        - image: registry.knatofs.se/go-cart-actor:latest
-          name: cart-actor-arm64
-          imagePullPolicy: Always
-          lifecycle:
-            preStop:
-              exec:
-                command: ["sleep", "15"]
-          ports:
-            - containerPort: 8080
-              name: web
-            - containerPort: 1234
-              name: echo
-            - containerPort: 1337
-              name: rpc
-            - containerPort: 1338
-              name: quorum
-          livenessProbe:
-            httpGet:
-              path: /livez
-              port: web
-            failureThreshold: 1
-            periodSeconds: 10
-          readinessProbe:
-            httpGet:
-              path: /readyz
-              port: web
-            failureThreshold: 2
-            initialDelaySeconds: 2
-            periodSeconds: 10
-          volumeMounts:
-            - mountPath: "/data"
-              name: data
-          resources:
-            limits:
-              memory: "768Mi"
-            requests:
-              memory: "70Mi"
-              cpu: "1200m"
-          env:
-            - name: TZ
-              value: "Europe/Stockholm"
-            - name: KLARNA_API_USERNAME
-              valueFrom:
-                secretKeyRef:
-                  name: klarna-api-credentials
-                  key: username
-            - name: KLARNA_API_PASSWORD
-              valueFrom:
-                secretKeyRef:
-                  name: klarna-api-credentials
-                  key: password
-            - name: POD_IP
-              valueFrom:
-                fieldRef:
-                  fieldPath: status.podIP
-            - name: AMQP_URL
-              value: "amqp://admin:12bananer@rabbitmq.dev:5672/"
-            - name: BASE_URL
-              value: "https://s10n-no.tornberg.me"
-            - name: CART_BASE_URL
-              value: "https://cart-no.tornberg.me"
-            - name: POD_NAME
-              valueFrom:
-                fieldRef:
-                  fieldPath: metadata.name
----
-kind: Service
-apiVersion: v1
-metadata:
-  name: cart-echo
-spec:
-  selector:
-    app: cart-actor
-  type: LoadBalancer
-  ports:
-    - name: echo
-      port: 1234
----
-kind: Service
-apiVersion: v1
-metadata:
-  name: cart-actor
-  annotations:
-    prometheus.io/port: "8080"
-    prometheus.io/scrape: "true"
-    prometheus.io/path: "/metrics"
-spec:
-  selector:
-    app: cart-actor
-  ports:
-    - name: web
-      port: 8080
----
-apiVersion: networking.k8s.io/v1
-kind: Ingress
-metadata:
-  name: cart-ingress
-  annotations:
-    cert-manager.io/cluster-issuer: letsencrypt-prod
-    # nginx.ingress.kubernetes.io/affinity: "cookie"
-    # nginx.ingress.kubernetes.io/session-cookie-name: "cart-affinity"
-    # nginx.ingress.kubernetes.io/session-cookie-expires: "172800"
-    # nginx.ingress.kubernetes.io/session-cookie-max-age: "172800"
-    nginx.ingress.kubernetes.io/proxy-body-size: 4m
-spec:
-  ingressClassName: nginx
-  tls:
-    - hosts:
-        - cart-no.tornberg.me
-      secretName: cart-actor-no-tls-secret
-  rules:
-    - host: cart-no.tornberg.me
-      http:
-        paths:
-          - path: /
-            pathType: Prefix
-            backend:
-              service:
-                name: cart-actor
-                port:
-                  number: 8080

deployment/deployment.yaml

@@ -1,7 +1,7 @@
 apiVersion: v1
 kind: Secret
 metadata:
-  name:  klarna-api-credentials
+  name: klarna-api-credentials
 data:
   username: ZjQzZDY3YjEtNzA2Yy00NTk2LTliNTgtYjg1YjU2NDEwZTUw
   password: a2xhcm5hX3Rlc3RfYXBpX0trUWhWVE5yYVZsV2FsTnhTRVp3Y1ZSSFF5UkVNRmxyY25Kd1AxSndQMGdzWmpRelpEWTNZakV0TnpBMll5MDBOVGsyTFRsaU5UZ3RZamcxWWpVMk5ERXdaVFV3TERFc2JUUkNjRFpWU1RsTllsSk1aMlEyVEc4MmRVODNZMkozUlRaaFdEZDViV3AwYkhGV1JqTjVNQzlaYXow
@@ -11,20 +11,19 @@ apiVersion: apps/v1
 kind: Deployment
 metadata:
   labels:
-    app: cart-actor
+    app: cart-backoffice
     arch: amd64
-  name: cart-actor-x86
+  name: cart-backoffice-x86
 spec:
-  replicas: 0
+  replicas: 1
   selector:
     matchLabels:
-      app: cart-actor
+      app: cart-backoffice
       arch: amd64
   template:
     metadata:
       labels:
-        app: cart-actor
+        app: cart-backoffice
-        actor-pool: cart
         arch: amd64
     spec:
       affinity:
@@ -32,22 +31,21 @@ spec:
           requiredDuringSchedulingIgnoredDuringExecution:
             nodeSelectorTerms:
               - matchExpressions:
-                - key: kubernetes.io/arch
+                  - key: kubernetes.io/arch
-                  operator: NotIn
+                    operator: NotIn
-                  values:
+                    values:
-                    - arm64
+                      - arm64
       volumes:
         - name: data
           nfs:
             path: /i-data/7a8af061/nfs/cart-actor
             server: 10.10.1.10
-      imagePullSecrets:
-        - name: regcred
       serviceAccountName: default
       containers:
-        - image: registry.knatofs.se/go-cart-actor-amd64:latest
+        - image: registry.k6n.net/go-cart-actor-amd64:latest
           name: cart-actor-amd64
           imagePullPolicy: Always
+          command: ["/go-cart-backoffice"]
           lifecycle:
             preStop:
               exec:
@@ -55,25 +53,19 @@ spec:
           ports:
             - containerPort: 8080
               name: web
-            - containerPort: 1234
-              name: echo
-            - containerPort: 1337
-              name: rpc
-            - containerPort: 1338
-              name: quorum
           livenessProbe:
             httpGet:
               path: /livez
               port: web
             failureThreshold: 1
-            periodSeconds: 10
+            periodSeconds: 30
           readinessProbe:
             httpGet:
               path: /readyz
               port: web
             failureThreshold: 2
             initialDelaySeconds: 2
-            periodSeconds: 10
+            periodSeconds: 30
           volumeMounts:
             - mountPath: "/data"
               name: data
@@ -96,6 +88,104 @@ spec:
                 secretKeyRef:
                   name: klarna-api-credentials
                   key: password
+            - name: AMQP_URL
+              value: "amqp://admin:12bananer@rabbitmq.dev:5672/"
+            # - name: BASE_URL
+            #   value: "https://s10n-no.tornberg.me"
+---
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  labels:
+    app: cart-actor
+    arch: amd64
+  name: cart-actor-x86
+spec:
+  replicas: 3
+  selector:
+    matchLabels:
+      app: cart-actor
+      arch: amd64
+  template:
+    metadata:
+      labels:
+        app: cart-actor
+        actor-pool: cart
+        arch: amd64
+    spec:
+      affinity:
+        nodeAffinity:
+          requiredDuringSchedulingIgnoredDuringExecution:
+            nodeSelectorTerms:
+              - matchExpressions:
+                  - key: kubernetes.io/arch
+                    operator: NotIn
+                    values:
+                      - arm64
+      volumes:
+        - name: data
+          nfs:
+            path: /i-data/7a8af061/nfs/cart-actor
+            server: 10.10.1.10
+      serviceAccountName: default
+      containers:
+        - image: registry.k6n.net/go-cart-actor-amd64:latest
+          name: cart-actor-amd64
+          imagePullPolicy: Always
+          lifecycle:
+            preStop:
+              exec:
+                command: ["sleep", "15"]
+          ports:
+            - containerPort: 8080
+              name: web
+            - containerPort: 8081
+              name: debug
+            - containerPort: 1337
+              name: rpc
+          livenessProbe:
+            httpGet:
+              path: /livez
+              port: web
+            failureThreshold: 1
+            periodSeconds: 30
+          readinessProbe:
+            httpGet:
+              path: /readyz
+              port: web
+            failureThreshold: 2
+            initialDelaySeconds: 2
+            periodSeconds: 50
+          volumeMounts:
+            - mountPath: "/data"
+              name: data
+          resources:
+            limits:
+              memory: "768Mi"
+            requests:
+              memory: "70Mi"
+              cpu: "1200m"
+          env:
+            - name: TZ
+              value: "Europe/Stockholm"
+            - name: KLARNA_API_USERNAME
+              valueFrom:
+                secretKeyRef:
+                  name: klarna-api-credentials
+                  key: username
+            - name: REDIS_ADDRESS
+              value: "10.10.3.18:6379"
+            - name: REDIS_PASSWORD
+              value: "slaskredis"
+            - name: OTEL_RESOURCE_ATTRIBUTES
+              value: "service.name=cart,service.version=0.1.2"
+            - name: OTEL_EXPORTER_OTLP_ENDPOINT
+              value: "http://otel-debug-service.monitoring:4317"
+            - name: KLARNA_API_PASSWORD
+              valueFrom:
+                secretKeyRef:
+                  name: klarna-api-credentials
+                  key: password
             - name: POD_IP
               valueFrom:
                 fieldRef:
@@ -134,24 +224,22 @@ spec:
           requiredDuringSchedulingIgnoredDuringExecution:
             nodeSelectorTerms:
               - matchExpressions:
-                - key: kubernetes.io/hostname
+                  - key: kubernetes.io/hostname
-                  operator: NotIn
+                    operator: NotIn
-                  values:
+                    values:
-                    - masterpi
+                      - masterpi
-                - key: kubernetes.io/arch
+                  - key: kubernetes.io/arch
-                  operator: In
+                    operator: In
-                  values:
+                    values:
-                    - arm64
+                      - arm64
       volumes:
         - name: data
           nfs:
             path: /i-data/7a8af061/nfs/cart-actor
             server: 10.10.1.10
-      imagePullSecrets:
-        - name: regcred
       serviceAccountName: default
       containers:
-        - image: registry.knatofs.se/go-cart-actor:latest
+        - image: registry.k6n.net/go-cart-actor:latest
           name: cart-actor-arm64
           imagePullPolicy: Always
           lifecycle:
@@ -161,25 +249,23 @@ spec:
           ports:
             - containerPort: 8080
               name: web
-            - containerPort: 1234
+            - containerPort: 8081
-              name: echo
+              name: debug
             - containerPort: 1337
               name: rpc
-            - containerPort: 1338
-              name: quorum
           livenessProbe:
             httpGet:
               path: /livez
               port: web
             failureThreshold: 1
-            periodSeconds: 10
+            periodSeconds: 30
           readinessProbe:
             httpGet:
               path: /readyz
               port: web
             failureThreshold: 2
             initialDelaySeconds: 2
-            periodSeconds: 10
+            periodSeconds: 30
           volumeMounts:
             - mountPath: "/data"
               name: data
@@ -192,6 +278,14 @@ spec:
           env:
             - name: TZ
               value: "Europe/Stockholm"
+            - name: REDIS_ADDRESS
+              value: "redis.home:6379"
+            - name: REDIS_PASSWORD
+              value: "slaskredis"
+            - name: OTEL_RESOURCE_ATTRIBUTES
+              value: "service.name=cart,service.version=0.1.2"
+            - name: OTEL_EXPORTER_OTLP_ENDPOINT
+              value: "http://otel-debug-service.monitoring:4317"
             - name: KLARNA_API_USERNAME
               valueFrom:
                 secretKeyRef:
@@ -217,22 +311,10 @@ spec:
 ---
 kind: Service
 apiVersion: v1
-metadata:
-  name: cart-echo
-spec:
-  selector:
-    app: cart-actor
-  type: LoadBalancer
-  ports:
-    - name: echo
-      port: 1234
----
-kind: Service
-apiVersion: v1
 metadata:
   name: cart-actor
   annotations:
-    prometheus.io/port: "8080"
+    prometheus.io/port: "8081"
     prometheus.io/scrape: "true"
     prometheus.io/path: "/metrics"
 spec:
@@ -242,16 +324,27 @@ spec:
     - name: web
       port: 8080
 ---
+kind: Service
+apiVersion: v1
+metadata:
+  name: cart-backoffice
+spec:
+  selector:
+    app: cart-backoffice
+  ports:
+    - name: web
+      port: 8080
+---
 apiVersion: networking.k8s.io/v1
 kind: Ingress
 metadata:
   name: cart-ingress
   annotations:
     cert-manager.io/cluster-issuer: letsencrypt-prod
-    # nginx.ingress.kubernetes.io/affinity: "cookie"
+    nginx.ingress.kubernetes.io/affinity: "cookie"
-    # nginx.ingress.kubernetes.io/session-cookie-name: "cart-affinity"
+    nginx.ingress.kubernetes.io/session-cookie-name: "cart-affinity"
-    # nginx.ingress.kubernetes.io/session-cookie-expires: "172800"
+    nginx.ingress.kubernetes.io/session-cookie-expires: "172800"
-    # nginx.ingress.kubernetes.io/session-cookie-max-age: "172800"
+    nginx.ingress.kubernetes.io/session-cookie-max-age: "172800"
     nginx.ingress.kubernetes.io/proxy-body-size: 4m
 spec:
   ingressClassName: nginx
@@ -269,4 +362,99 @@ spec:
               service:
                 name: cart-actor
                 port:
-                  number: 8080
+                  number: 8080
+---
+apiVersion: networking.k8s.io/v1
+kind: Ingress
+metadata:
+  name: cart-backend-ingress
+  annotations:
+    cert-manager.io/cluster-issuer: letsencrypt-prod
+spec:
+  ingressClassName: nginx
+  tls:
+    - hosts:
+        - slask-cart.tornberg.me
+      secretName: cart-backoffice-actor-tls-secret
+  rules:
+    - host: slask-cart.tornberg.me
+      http:
+        paths:
+          - path: /
+            pathType: Prefix
+            backend:
+              service:
+                name: cart-backoffice
+                port:
+                  number: 8080
+---
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  labels:
+    app: cart-inventory
+    arch: amd64
+  name: cart-inventory-x86
+spec:
+  replicas: 1
+  selector:
+    matchLabels:
+      app: cart-inventory
+      arch: amd64
+  template:
+    metadata:
+      labels:
+        app: cart-inventory
+        arch: amd64
+    spec:
+      affinity:
+        nodeAffinity:
+          requiredDuringSchedulingIgnoredDuringExecution:
+            nodeSelectorTerms:
+              - matchExpressions:
+                  - key: kubernetes.io/arch
+                    operator: NotIn
+                    values:
+                      - arm64
+      serviceAccountName: default
+      containers:
+        - image: registry.k6n.net/go-cart-actor-amd64:latest
+          name: cart-inventory-amd64
+          imagePullPolicy: Always
+          command: ["/go-cart-inventory"]
+          lifecycle:
+            preStop:
+              exec:
+                command: ["sleep", "15"]
+          ports:
+            - containerPort: 8080
+              name: web
+          livenessProbe:
+            httpGet:
+              path: /livez
+              port: web
+            failureThreshold: 1
+            periodSeconds: 30
+          readinessProbe:
+            httpGet:
+              path: /readyz
+              port: web
+            failureThreshold: 2
+            initialDelaySeconds: 2
+            periodSeconds: 30
+          resources:
+            limits:
+              memory: "256Mi"
+              cpu: "500m"
+            requests:
+              memory: "50Mi"
+              cpu: "500m"
+          env:
+            - name: TZ
+              value: "Europe/Stockholm"
+            - name: RABBIT_HOST
+              value: amqp://admin:12bananer@rabbitmq.s10n:5672/
+            - name: REDIS_ADDRESS
+              value: "redis.home:6379"
+            - name: REDIS_PASSWORD
+              value: "slaskredis"

deployment/scaling.yaml

@@ -1,25 +1,101 @@
-apiVersion: autoscaling/v1
+apiVersion: autoscaling/v2
 kind: HorizontalPodAutoscaler
 metadata:
-  name: cart-scaler-amd
+    name: cart-scaler-amd
 spec:
-  scaleTargetRef:
+    scaleTargetRef:
-    apiVersion: apps/v1
+        apiVersion: apps/v1
-    kind: Deployment
+        kind: Deployment
-    name: cart-actor-x86
+        name: cart-actor-x86
-  minReplicas: 3
+    minReplicas: 3
-  maxReplicas: 9
+    maxReplicas: 9
-  targetCPUUtilizationPercentage: 30
+    behavior:
+        scaleUp:
+            stabilizationWindowSeconds: 60
+            policies:
+                - type: Percent
+                  value: 100
+                  periodSeconds: 60
+        scaleDown:
+            stabilizationWindowSeconds: 180
+            policies:
+                - type: Percent
+                  value: 50
+                  periodSeconds: 60
+    metrics:
+        - type: Resource
+          resource:
+              name: cpu
+              target:
+                  type: Utilization
+                  averageUtilization: 50
+        # Future custom metric (example):
+        # - type: Pods
+        #   pods:
+        #     metric:
+        #       name: cart_mutations_per_second
+        #     target:
+        #       type: AverageValue
+        #       averageValue: "15"
+        # - type: Object
+        #   object:
+        #     describedObject:
+        #       apiVersion: networking.k8s.io/v1
+        #       kind: Ingress
+        #       name: cart-ingress
+        #     metric:
+        #       name: http_requests_per_second
+        #     target:
+        #       type: Value
+        #       value: "100"
 ---
-apiVersion: autoscaling/v1
+apiVersion: autoscaling/v2
 kind: HorizontalPodAutoscaler
 metadata:
-  name: cart-scaler-arm
+    name: cart-scaler-arm
 spec:
-  scaleTargetRef:
+    scaleTargetRef:
-    apiVersion: apps/v1
+        apiVersion: apps/v1
-    kind: Deployment
+        kind: Deployment
-    name: cart-actor-arm64
+        name: cart-actor-arm64
-  minReplicas: 3
+    minReplicas: 3
-  maxReplicas: 9
+    maxReplicas: 9
-  targetCPUUtilizationPercentage: 30
+    behavior:
+        scaleUp:
+            stabilizationWindowSeconds: 60
+            policies:
+                - type: Percent
+                  value: 100
+                  periodSeconds: 60
+        scaleDown:
+            stabilizationWindowSeconds: 180
+            policies:
+                - type: Percent
+                  value: 50
+                  periodSeconds: 60
+    metrics:
+        - type: Resource
+          resource:
+              name: cpu
+              target:
+                  type: Utilization
+                  averageUtilization: 50
+        # Future custom metric (example):
+        # - type: Pods
+        #   pods:
+        #     metric:
+        #       name: cart_mutations_per_second
+        #     target:
+        #       type: AverageValue
+        #       averageValue: "15"
+        # - type: Object
+        #   object:
+        #     describedObject:
+        #       apiVersion: networking.k8s.io/v1
+        #       kind: Ingress
+        #       name: cart-ingress
+        #     metric:
+        #       name: http_requests_per_second
+        #     target:
+        #       type: Value
+        #       value: "100"

discarded-host.go

@@ -1,83 +0,0 @@
-package main
-
-import (
-	"fmt"
-	"log"
-	"net"
-	"sync"
-	"time"
-)
-
-type DiscardedHost struct {
-	*Connection
-	Host  string
-	Tries int
-}
-
-type DiscardedHostHandler struct {
-	mu           sync.RWMutex
-	port         int
-	hosts        []*DiscardedHost
-	onConnection *func(string)
-}
-
-func (d *DiscardedHostHandler) run() {
-	for range time.Tick(time.Second) {
-		d.mu.RLock()
-		lst := make([]*DiscardedHost, 0, len(d.hosts))
-		for _, host := range d.hosts {
-			if host.Tries >= 0 || host.Tries < 5 {
-				go d.testConnection(host)
-				lst = append(lst, host)
-			} else {
-				if host.Tries > 0 {
-					log.Printf("Host %s discarded after %d tries", host.Host, host.Tries)
-				}
-			}
-		}
-		d.mu.RUnlock()
-		d.mu.Lock()
-		d.hosts = lst
-		d.mu.Unlock()
-	}
-
-}
-
-func (d *DiscardedHostHandler) testConnection(host *DiscardedHost) {
-	addr := fmt.Sprintf("%s:%d", host.Host, d.port)
-	conn, err := net.Dial("tcp", addr)
-
-	if err != nil {
-		host.Tries++
-		host.Tries = -1
-	} else {
-		conn.Close()
-		if d.onConnection != nil {
-			fn := *d.onConnection
-			fn(host.Host)
-		}
-	}
-}
-
-func NewDiscardedHostHandler(port int) *DiscardedHostHandler {
-	ret := &DiscardedHostHandler{
-		hosts: make([]*DiscardedHost, 0),
-		port:  port,
-	}
-	go ret.run()
-	return ret
-}
-
-func (d *DiscardedHostHandler) SetReconnectHandler(fn func(string)) {
-	d.onConnection = &fn
-}
-
-func (d *DiscardedHostHandler) AppendHost(host string) {
-	d.mu.Lock()
-	defer d.mu.Unlock()
-	log.Printf("Adding host %s to retry list", host)
-	d.hosts = append(d.hosts, &DiscardedHost{
-		Host:  host,
-		Tries: 0,
-	})
-}

discarded-host_test.go

@@ -1,18 +0,0 @@
-package main
-
-import (
-	"testing"
-	"time"
-)
-
-func TestDiscardedHost(t *testing.T) {
-	dh := NewDiscardedHostHandler(8080)
-	dh.SetReconnectHandler(func(host string) {
-		t.Log(host)
-	})
-	dh.AppendHost("localhost")
-	time.Sleep(2 * time.Second)
-	if dh.hosts[0].Tries == 0 {
-		t.Error("Host not tested")
-	}
-}

disk-storage.go

@@ -1,119 +0,0 @@
-package main
-
-import (
-	"encoding/gob"
-	"fmt"
-	"log"
-	"os"
-	"time"
-)
-
-type DiskStorage struct {
-	stateFile string
-	lastSave  int64
-	LastSaves map[CartId]int64
-}
-
-func NewDiskStorage(stateFile string) (*DiskStorage, error) {
-	ret := &DiskStorage{
-		stateFile: stateFile,
-		LastSaves: make(map[CartId]int64),
-	}
-	err := ret.loadState()
-	return ret, err
-}
-
-func saveMessages(messages []StorableMessage, id CartId) error {
-
-	if len(messages) == 0 {
-		return nil
-	}
-	log.Printf("%d messages to save for grain id %s", len(messages), id)
-	var file *os.File
-	var err error
-	path := getCartPath(id.String())
-	file, err = os.OpenFile(path, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
-	if err != nil {
-		return err
-	}
-	defer file.Close()
-
-	for _, m := range messages {
-		err := m.Write(file)
-		if err != nil {
-			return err
-		}
-	}
-	return err
-}
-
-func getCartPath(id string) string {
-	return fmt.Sprintf("data/%s.prot", id)
-}
-
-func loadMessages(grain Grain, id CartId) error {
-	var err error
-	path := getCartPath(id.String())
-
-	file, err := os.Open(path)
-	if err != nil {
-		if os.IsNotExist(err) {
-			return nil
-		}
-		return err
-	}
-	defer file.Close()
-
-	for err == nil {
-		var msg Message
-		err = ReadMessage(file, &msg)
-		if err == nil {
-			grain.HandleMessage(&msg, true)
-		}
-	}
-
-	if err.Error() == "EOF" {
-		return nil
-	}
-	return err
-}
-
-func (s *DiskStorage) saveState() error {
-	tmpFile := s.stateFile + "_tmp"
-	file, err := os.Create(tmpFile)
-	if err != nil {
-		return err
-	}
-	defer file.Close()
-	err = gob.NewEncoder(file).Encode(s.LastSaves)
-	if err != nil {
-		return err
-	}
-	os.Remove(s.stateFile + ".bak")
-	os.Rename(s.stateFile, s.stateFile+".bak")
-	return os.Rename(tmpFile, s.stateFile)
-}
-
-func (s *DiskStorage) loadState() error {
-	file, err := os.Open(s.stateFile)
-	if err != nil {
-		return err
-	}
-	defer file.Close()
-	return gob.NewDecoder(file).Decode(&s.LastSaves)
-}
-
-func (s *DiskStorage) Store(id CartId, grain *CartGrain) error {
-	lastSavedMessage, ok := s.LastSaves[id]
-	if ok && lastSavedMessage > grain.GetLastChange() {
-		return nil
-	}
-	err := saveMessages(grain.GetStorageMessage(lastSavedMessage), id)
-	if err != nil {
-		return err
-	}
-	ts := time.Now().Unix()
-	s.LastSaves[id] = ts
-	s.lastSave = ts
-	return nil
-}

go.mod

@@ -1,63 +1,117 @@
 module git.tornberg.me/go-cart-actor
 
-go 1.24.2
+go 1.25.3
 
 require (
-	github.com/matst80/slask-finder v0.0.0-20250418094723-2eb7d6615761
+	git.tornberg.me/mats/go-redis-inventory v0.0.0-20251113201741-8bf0efac50ee
-	github.com/prometheus/client_golang v1.22.0
+	github.com/gogo/protobuf v1.3.2
+	github.com/google/uuid v1.6.0
+	github.com/matst80/slask-finder v0.0.0-20251118173753-f66c21cfbda4
+	github.com/prometheus/client_golang v1.23.2
 	github.com/rabbitmq/amqp091-go v1.10.0
-	github.com/yudhasubki/netpool v0.0.0-20230717065341-3c1353ca328e
+	github.com/redis/go-redis/v9 v9.16.0
-	google.golang.org/protobuf v1.36.6
+	go.opentelemetry.io/contrib/bridges/otelslog v0.13.0
-	k8s.io/api v0.32.3
+	go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.63.0
-	k8s.io/apimachinery v0.32.3
+	go.opentelemetry.io/otel v1.38.0
-	k8s.io/client-go v0.32.3
+	go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploggrpc v0.14.0
+	go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc v1.38.0
+	go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc v1.38.0
+	go.opentelemetry.io/otel/log v0.14.0
+	go.opentelemetry.io/otel/metric v1.38.0
+	go.opentelemetry.io/otel/sdk v1.38.0
+	go.opentelemetry.io/otel/sdk/log v0.14.0
+	go.opentelemetry.io/otel/sdk/metric v1.38.0
+	go.opentelemetry.io/otel/trace v1.38.0
+	google.golang.org/grpc v1.77.0
+	google.golang.org/protobuf v1.36.10
+	k8s.io/api v0.34.2
+	k8s.io/apimachinery v0.34.2
+	k8s.io/client-go v0.34.2
 )
 
 require (
+	github.com/RoaringBitmap/roaring/v2 v2.14.4 // indirect
 	github.com/beorn7/perks v1.0.1 // indirect
+	github.com/bits-and-blooms/bitset v1.24.4 // indirect
+	github.com/cenkalti/backoff/v5 v5.0.3 // indirect
 	github.com/cespare/xxhash/v2 v2.3.0 // indirect
 	github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc // indirect
 	github.com/dgryski/go-rendezvous v0.0.0-20200823014737-9f7001d12a5f // indirect
-	github.com/emicklei/go-restful/v3 v3.12.2 // indirect
+	github.com/dprotaso/go-yit v0.0.0-20251117151522-da16f3077589 // indirect
-	github.com/fxamacker/cbor/v2 v2.8.0 // indirect
+	github.com/emicklei/go-restful/v3 v3.13.0 // indirect
-	github.com/go-logr/logr v1.4.2 // indirect
+	github.com/felixge/httpsnoop v1.0.4 // indirect
-	github.com/go-openapi/jsonpointer v0.21.1 // indirect
+	github.com/fxamacker/cbor/v2 v2.9.0 // indirect
-	github.com/go-openapi/jsonreference v0.21.0 // indirect
+	github.com/getkin/kin-openapi v0.133.0 // indirect
-	github.com/go-openapi/swag v0.23.1 // indirect
+	github.com/go-logr/logr v1.4.3 // indirect
-	github.com/gogo/protobuf v1.3.2 // indirect
+	github.com/go-logr/stdr v1.2.2 // indirect
-	github.com/golang/protobuf v1.5.4 // indirect
+	github.com/go-openapi/jsonpointer v0.22.3 // indirect
-	github.com/google/gnostic-models v0.6.9 // indirect
+	github.com/go-openapi/jsonreference v0.21.3 // indirect
+	github.com/go-openapi/swag v0.25.3 // indirect
+	github.com/go-openapi/swag/cmdutils v0.25.3 // indirect
+	github.com/go-openapi/swag/conv v0.25.3 // indirect
+	github.com/go-openapi/swag/fileutils v0.25.3 // indirect
+	github.com/go-openapi/swag/jsonname v0.25.3 // indirect
+	github.com/go-openapi/swag/jsonutils v0.25.3 // indirect
+	github.com/go-openapi/swag/loading v0.25.3 // indirect
+	github.com/go-openapi/swag/mangling v0.25.3 // indirect
+	github.com/go-openapi/swag/netutils v0.25.3 // indirect
+	github.com/go-openapi/swag/stringutils v0.25.3 // indirect
+	github.com/go-openapi/swag/typeutils v0.25.3 // indirect
+	github.com/go-openapi/swag/yamlutils v0.25.3 // indirect
+	github.com/google/gnostic-models v0.7.0 // indirect
 	github.com/google/go-cmp v0.7.0 // indirect
-	github.com/google/gofuzz v1.2.0 // indirect
+	github.com/gorilla/schema v1.4.1 // indirect
-	github.com/google/uuid v1.6.0 // indirect
+	github.com/grpc-ecosystem/grpc-gateway/v2 v2.27.3 // indirect
 	github.com/josharian/intern v1.0.0 // indirect
 	github.com/json-iterator/go v1.1.12 // indirect
-	github.com/mailru/easyjson v0.9.0 // indirect
+	github.com/mailru/easyjson v0.9.1 // indirect
 	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
-	github.com/modern-go/reflect2 v1.0.2 // indirect
+	github.com/modern-go/reflect2 v1.0.3-0.20250322232337-35a7c28c31ee // indirect
+	github.com/mohae/deepcopy v0.0.0-20170929034955-c48cc78d4826 // indirect
+	github.com/mschoch/smat v0.2.0 // indirect
 	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
-	github.com/pkg/errors v0.9.1 // indirect
+	github.com/oapi-codegen/oapi-codegen/v2 v2.5.1 // indirect
+	github.com/oasdiff/yaml v0.0.0-20250309154309-f31be36b4037 // indirect
+	github.com/oasdiff/yaml3 v0.0.0-20250309153720-d2182401db90 // indirect
+	github.com/perimeterx/marshmallow v1.1.5 // indirect
+	github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 // indirect
 	github.com/prometheus/client_model v0.6.2 // indirect
-	github.com/prometheus/common v0.63.0 // indirect
+	github.com/prometheus/common v0.67.3 // indirect
-	github.com/prometheus/procfs v0.16.0 // indirect
+	github.com/prometheus/procfs v0.19.2 // indirect
-	github.com/redis/go-redis/v9 v9.7.0 // indirect
+	github.com/speakeasy-api/jsonpath v0.6.2 // indirect
-	github.com/spf13/pflag v1.0.6 // indirect
+	github.com/speakeasy-api/openapi-overlay v0.10.3 // indirect
+	github.com/spf13/pflag v1.0.10 // indirect
+	github.com/vmware-labs/yaml-jsonpath v0.3.2 // indirect
+	github.com/woodsbury/decimal128 v1.3.0 // indirect
 	github.com/x448/float16 v0.8.4 // indirect
-	golang.org/x/net v0.39.0 // indirect
+	go.opentelemetry.io/auto/sdk v1.2.1 // indirect
-	golang.org/x/oauth2 v0.29.0 // indirect
+	go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.38.0 // indirect
-	golang.org/x/sys v0.32.0 // indirect
+	go.opentelemetry.io/proto/otlp v1.9.0 // indirect
-	golang.org/x/term v0.31.0 // indirect
+	go.yaml.in/yaml/v2 v2.4.3 // indirect
-	golang.org/x/text v0.24.0 // indirect
+	go.yaml.in/yaml/v3 v3.0.4 // indirect
-	golang.org/x/time v0.11.0 // indirect
+	go.yaml.in/yaml/v4 v4.0.0-rc.3 // indirect
-	golang.org/x/tools v0.32.0 // indirect
+	golang.org/x/mod v0.30.0 // indirect
-	gopkg.in/evanphx/json-patch.v4 v4.12.0 // indirect
+	golang.org/x/net v0.47.0 // indirect
+	golang.org/x/oauth2 v0.33.0 // indirect
+	golang.org/x/sync v0.18.0 // indirect
+	golang.org/x/sys v0.38.0 // indirect
+	golang.org/x/term v0.37.0 // indirect
+	golang.org/x/text v0.31.0 // indirect
+	golang.org/x/time v0.14.0 // indirect
+	golang.org/x/tools v0.39.0 // indirect
+	google.golang.org/genproto/googleapis/api v0.0.0-20251111163417-95abcf5c77ba // indirect
+	google.golang.org/genproto/googleapis/rpc v0.0.0-20251111163417-95abcf5c77ba // indirect
+	gopkg.in/evanphx/json-patch.v4 v4.13.0 // indirect
 	gopkg.in/inf.v0 v0.9.1 // indirect
+	gopkg.in/yaml.v2 v2.4.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 	k8s.io/klog/v2 v2.130.1 // indirect
-	k8s.io/kube-openapi v0.0.0-20250318190949-c8a335a9a2ff // indirect
+	k8s.io/kube-openapi v0.0.0-20250910181357-589584f1c912 // indirect
-	k8s.io/utils v0.0.0-20250321185631-1f6e0b77f77e // indirect
+	k8s.io/utils v0.0.0-20251002143259-bc988d571ff4 // indirect
-	sigs.k8s.io/json v0.0.0-20241014173422-cfa47c3a1cc8 // indirect
+	sigs.k8s.io/json v0.0.0-20250730193827-2d320260d730 // indirect
 	sigs.k8s.io/randfill v1.0.0 // indirect
-	sigs.k8s.io/structured-merge-diff/v4 v4.7.0 // indirect
+	sigs.k8s.io/structured-merge-diff/v6 v6.3.0 // indirect
-	sigs.k8s.io/yaml v1.4.0 // indirect
+	sigs.k8s.io/yaml v1.6.0 // indirect
 )
+
+tool github.com/oapi-codegen/oapi-codegen/v2/cmd/oapi-codegen

go.sum

@@ -1,11 +1,17 @@
-github.com/Flaconi/go-klarna v0.0.0-20230216165926-e2f708c721d9 h1:U5gu3M9/khqtvgg6iRKo0+nxGEfPHWFHRlKrbZvFxIY=
+git.tornberg.me/mats/go-redis-inventory v0.0.0-20251113201741-8bf0efac50ee h1:9K/INdO9y/hAjlERsYkJWAla6BUEAPXtChVLfYtWdGI=
-github.com/Flaconi/go-klarna v0.0.0-20230216165926-e2f708c721d9/go.mod h1:+LVFV9FXH5cwN1VcU30WcNYRs5FhkEtL7/IqqTD42cU=
+git.tornberg.me/mats/go-redis-inventory v0.0.0-20251113201741-8bf0efac50ee/go.mod h1:jrDU55O7sdN2RJr99upmig/FAla/mW1Cdju7834TXug=
+github.com/RoaringBitmap/roaring/v2 v2.14.4 h1:4aKySrrg9G/5oRtJ3TrZLObVqxgQ9f1znCRBwEwjuVw=
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 sigs.k8s.io/randfill v1.0.0 h1:JfjMILfT8A6RbawdsK2JXGBR5AQVfd+9TbzrlneTyrU=
 sigs.k8s.io/randfill v1.0.0/go.mod h1:XeLlZ/jmk4i1HRopwe7/aU3H5n1zNUcX6TM94b3QxOY=
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+sigs.k8s.io/structured-merge-diff/v6 v6.3.0 h1:jTijUJbW353oVOd9oTlifJqOGEkUw2jB/fXCbTiQEco=
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-sigs.k8s.io/yaml v1.4.0 h1:Mk1wCc2gy/F0THH0TAp1QYyJNzRm2KCLy3o5ASXVI5E=
+sigs.k8s.io/yaml v1.6.0 h1:G8fkbMSAFqgEFgh4b1wmtzDnioxFCUgTZhlbj5P9QYs=
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grafana_dashboard_cart.json

@@ -0,0 +1,327 @@
+{
+  "uid": "cart-actors",
+  "title": "Cart Actor Cluster",
+  "timezone": "browser",
+  "refresh": "30s",
+  "schemaVersion": 38,
+  "version": 1,
+  "editable": true,
+  "graphTooltip": 0,
+  "panels": [
+    {
+      "type": "row",
+      "title": "Overview",
+      "gridPos": { "x": 0, "y": 0, "w": 24, "h": 1 },
+      "id": 1,
+      "collapsed": false
+    },
+    {
+      "type": "stat",
+      "title": "Active Grains",
+      "id": 2,
+      "gridPos": { "x": 0, "y": 1, "w": 6, "h": 4 },
+      "datasource": "${DS_PROMETHEUS}",
+      "targets": [
+        { "refId": "A", "expr": "cart_active_grains" }
+      ],
+      "options": {
+        "colorMode": "value",
+        "graphMode": "none",
+        "justifyMode": "center",
+        "reduceOptions": { "calcs": ["lastNotNull"], "fields": "", "values": false }
+      }
+    },
+    {
+      "type": "stat",
+      "title": "Grains In Pool",
+      "id": 3,
+      "gridPos": { "x": 6, "y": 1, "w": 6, "h": 4 },
+      "datasource": "${DS_PROMETHEUS}",
+      "targets": [
+        { "refId": "A", "expr": "cart_grains_in_pool" }
+      ],
+      "options": {
+        "colorMode": "value",
+        "graphMode": "none",
+        "justifyMode": "center",
+        "reduceOptions": { "calcs": ["lastNotNull"], "fields": "", "values": false }
+      }
+    },
+    {
+      "type": "stat",
+      "title": "Pool Usage %",
+      "id": 4,
+      "gridPos": { "x": 12, "y": 1, "w": 6, "h": 4 },
+      "datasource": "${DS_PROMETHEUS}",
+      "targets": [
+        { "refId": "A", "expr": "cart_grain_pool_usage * 100" }
+      ],
+      "units": "percent",
+      "options": {
+        "colorMode": "value",
+        "graphMode": "none",
+        "justifyMode": "center",
+        "reduceOptions": { "calcs": ["lastNotNull"] }
+      }
+    },
+    {
+      "type": "stat",
+      "title": "Connected Remotes",
+      "id": 5,
+      "gridPos": { "x": 18, "y": 1, "w": 6, "h": 4 },
+      "datasource": "${DS_PROMETHEUS}",
+      "targets": [
+        { "refId": "A", "expr": "connected_remotes" }
+      ],
+      "options": {
+        "colorMode": "value",
+        "graphMode": "none",
+        "justifyMode": "center",
+        "reduceOptions": { "calcs": ["lastNotNull"] }
+      }
+    },
+
+    {
+      "type": "row",
+      "title": "Mutations",
+      "gridPos": { "x": 0, "y": 5, "w": 24, "h": 1 },
+      "id": 6,
+      "collapsed": false
+    },
+    {
+      "type": "timeseries",
+      "title": "Mutation Rate (1m)",
+      "id": 7,
+      "gridPos": { "x": 0, "y": 6, "w": 12, "h": 8 },
+      "datasource": "${DS_PROMETHEUS}",
+      "targets": [
+        { "refId": "A", "expr": "rate(cart_mutations_total[1m])", "legendFormat": "mutations/s" },
+        { "refId": "B", "expr": "rate(cart_mutation_failures_total[1m])", "legendFormat": "failures/s" }
+      ],
+      "fieldConfig": { "defaults": { "unit": "ops" } }
+    },
+    {
+      "type": "stat",
+      "title": "Failure % (5m)",
+      "id": 8,
+      "gridPos": { "x": 12, "y": 6, "w": 6, "h": 4 },
+      "datasource": "${DS_PROMETHEUS}",
+      "targets": [
+        {
+          "refId": "A",
+          "expr": "100 * (increase(cart_mutation_failures_total[5m]) / clamp_max(increase(cart_mutations_total[5m]), 1))"
+        }
+      ],
+      "options": {
+        "colorMode": "value",
+        "graphMode": "none",
+        "justifyMode": "center",
+        "reduceOptions": { "calcs": ["lastNotNull"] }
+      }
+    },
+    {
+      "type": "timeseries",
+      "title": "Mutation Latency Quantiles",
+      "id": 9,
+      "gridPos": { "x": 18, "y": 6, "w": 6, "h": 8 },
+      "datasource": "${DS_PROMETHEUS}",
+      "targets": [
+        {
+          "refId": "A",
+          "expr": "histogram_quantile(0.50, sum(rate(cart_mutation_latency_seconds_bucket[5m])) by (le))",
+          "legendFormat": "p50"
+        },
+        {
+          "refId": "B",
+          "expr": "histogram_quantile(0.90, sum(rate(cart_mutation_latency_seconds_bucket[5m])) by (le))",
+          "legendFormat": "p90"
+        },
+        {
+          "refId": "C",
+          "expr": "histogram_quantile(0.99, sum(rate(cart_mutation_latency_seconds_bucket[5m])) by (le))",
+          "legendFormat": "p99"
+        }
+      ],
+      "fieldConfig": { "defaults": { "unit": "s" } }
+    },
+
+    {
+      "type": "row",
+      "title": "Event Log",
+      "gridPos": { "x": 0, "y": 14, "w": 24, "h": 1 },
+      "id": 10,
+      "collapsed": false
+    },
+    {
+      "type": "timeseries",
+      "title": "Event Append Rate (5m)",
+      "id": 11,
+      "gridPos": { "x": 0, "y": 15, "w": 8, "h": 6 },
+      "datasource": "${DS_PROMETHEUS}",
+      "targets": [
+        { "refId": "A", "expr": "rate(cart_event_log_appends_total[5m])", "legendFormat": "appends/s" }
+      ]
+    },
+    {
+      "type": "timeseries",
+      "title": "Event Bytes Written Rate (5m)",
+      "id": 12,
+      "gridPos": { "x": 8, "y": 15, "w": 8, "h": 6 },
+      "datasource": "${DS_PROMETHEUS}",
+      "targets": [
+        { "refId": "A", "expr": "rate(cart_event_log_bytes_written_total[5m])", "legendFormat": "bytes/s" }
+      ],
+      "fieldConfig": { "defaults": { "unit": "Bps" } }
+    },
+    {
+      "type": "stat",
+      "title": "Existing Log Files",
+      "id": 13,
+      "gridPos": { "x": 16, "y": 15, "w": 4, "h": 3 },
+      "datasource": "${DS_PROMETHEUS}",
+      "targets": [{ "refId": "A", "expr": "cart_event_log_files_existing" }],
+      "options": { "reduceOptions": { "calcs": ["lastNotNull"] } }
+    },
+    {
+      "type": "stat",
+      "title": "Last Append Age (s)",
+      "id": 14,
+      "gridPos": { "x": 20, "y": 15, "w": 4, "h": 3 },
+      "datasource": "${DS_PROMETHEUS}",
+      "targets": [
+        { "refId": "A", "expr": "(time() - cart_event_log_last_append_unix)" }
+      ],
+      "options": { "reduceOptions": { "calcs": ["lastNotNull"] } }
+    },
+    {
+      "type": "stat",
+      "title": "Replay Failures Total",
+      "id": 15,
+      "gridPos": { "x": 16, "y": 18, "w": 4, "h": 3 },
+      "datasource": "${DS_PROMETHEUS}",
+      "targets": [{ "refId": "A", "expr": "cart_event_log_replay_failures_total" }],
+      "options": { "reduceOptions": { "calcs": ["lastNotNull"] } }
+    },
+    {
+      "type": "stat",
+      "title": "Replay Duration p95 (5m)",
+      "id": 16,
+      "gridPos": { "x": 20, "y": 18, "w": 4, "h": 3 },
+      "datasource": "${DS_PROMETHEUS}",
+      "targets": [
+        {
+          "refId": "A",
+            "expr": "histogram_quantile(0.95, sum(rate(cart_event_log_replay_duration_seconds_bucket[5m])) by (le))"
+        }
+      ],
+      "options": { "reduceOptions": { "calcs": ["lastNotNull"] }, "fieldConfig": { "defaults": { "unit": "s" } } }
+    },
+
+    {
+      "type": "row",
+      "title": "Grain Lifecycle",
+      "gridPos": { "x": 0, "y": 21, "w": 24, "h": 1 },
+      "id": 17,
+      "collapsed": false
+    },
+    {
+      "type": "timeseries",
+      "title": "Spawn & Lookup Rates (1m)",
+      "id": 18,
+      "gridPos": { "x": 0, "y": 22, "w": 12, "h": 8 },
+      "datasource": "${DS_PROMETHEUS}",
+      "targets": [
+        { "refId": "A", "expr": "rate(cart_grain_spawned_total[1m])", "legendFormat": "spawns/s" },
+        { "refId": "B", "expr": "rate(cart_grain_lookups_total[1m])", "legendFormat": "lookups/s" }
+      ]
+    },
+    {
+      "type": "stat",
+      "title": "Negotiations Rate (5m)",
+      "id": 19,
+      "gridPos": { "x": 12, "y": 22, "w": 6, "h": 4 },
+      "datasource": "${DS_PROMETHEUS}",
+      "targets": [
+        { "refId": "A", "expr": "rate(cart_remote_negotiation_total[5m])" }
+      ],
+      "options": { "reduceOptions": { "calcs": ["lastNotNull"] }, "orientation": "horizontal" }
+    },
+    {
+      "type": "stat",
+      "title": "Mutations Total",
+      "id": 20,
+      "gridPos": { "x": 18, "y": 22, "w": 6, "h": 4 },
+      "datasource": "${DS_PROMETHEUS}",
+      "targets": [{ "refId": "A", "expr": "cart_mutations_total" }],
+      "options": { "reduceOptions": { "calcs": ["lastNotNull"] } }
+    },
+
+    {
+      "type": "row",
+      "title": "Event Log Errors",
+      "gridPos": { "x": 0, "y": 30, "w": 24, "h": 1 },
+      "id": 21,
+      "collapsed": false
+    },
+    {
+      "type": "stat",
+      "title": "Unknown Event Types",
+      "id": 22,
+      "gridPos": { "x": 0, "y": 31, "w": 6, "h": 4 },
+      "datasource": "${DS_PROMETHEUS}",
+      "targets": [{ "refId": "A", "expr": "cart_event_log_unknown_types_total" }],
+      "options": { "reduceOptions": { "calcs": ["lastNotNull"] } }
+    },
+    {
+      "type": "stat",
+      "title": "Event Mutation Errors",
+      "id": 23,
+      "gridPos": { "x": 6, "y": 31, "w": 6, "h": 4 },
+      "datasource": "${DS_PROMETHEUS}",
+      "targets": [{ "refId": "A", "expr": "cart_event_log_mutation_errors_total" }],
+      "options": { "reduceOptions": { "calcs": ["lastNotNull"] } }
+    },
+    {
+      "type": "stat",
+      "title": "Replay Success Total",
+      "id": 24,
+      "gridPos": { "x": 12, "y": 31, "w": 6, "h": 4 },
+      "datasource": "${DS_PROMETHEUS}",
+      "targets": [{ "refId": "A", "expr": "cart_event_log_replay_total" }],
+      "options": { "reduceOptions": { "calcs": ["lastNotNull"] } }
+    },
+    {
+      "type": "stat",
+      "title": "Replay Duration p50 (5m)",
+      "id": 25,
+      "gridPos": { "x": 18, "y": 31, "w": 6, "h": 4 },
+      "datasource": "${DS_PROMETHEUS}",
+      "targets": [
+        {
+          "refId": "A",
+          "expr": "histogram_quantile(0.50, sum(rate(cart_event_log_replay_duration_seconds_bucket[5m])) by (le))"
+        }
+      ],
+      "options": { "reduceOptions": { "calcs": ["lastNotNull"] }, "fieldConfig": { "defaults": { "unit": "s" } } }
+    }
+  ],
+  "templating": {
+    "list": [
+      {
+        "name": "DS_PROMETHEUS",
+        "label": "Prometheus",
+        "type": "datasource",
+        "query": "prometheus",
+        "current": { "text": "Prometheus", "value": "Prometheus" }
+      }
+    ]
+  },
+  "time": {
+    "from": "now-6h",
+    "to": "now"
+  },
+  "timepicker": {
+    "refresh_intervals": ["5s","10s","30s","1m","5m","15m","30m","1h"],
+    "time_options": ["5m","15m","30m","1h","6h","12h","24h","2d","7d"]
+  }
+}

grain-pool.go

@@ -1,168 +0,0 @@
-package main
-
-import (
-	"encoding/json"
-	"fmt"
-	"log"
-	"sync"
-	"time"
-
-	"github.com/prometheus/client_golang/prometheus"
-	"github.com/prometheus/client_golang/prometheus/promauto"
-)
-
-var (
-	poolGrains = promauto.NewGauge(prometheus.GaugeOpts{
-		Name: "cart_grains_in_pool",
-		Help: "The total number of grains in the pool",
-	})
-	poolSize = promauto.NewGauge(prometheus.GaugeOpts{
-		Name: "cart_pool_size",
-		Help: "The total number of mutations",
-	})
-	poolUsage = promauto.NewGauge(prometheus.GaugeOpts{
-		Name: "cart_grain_pool_usage",
-		Help: "The current usage of the grain pool",
-	})
-)
-
-type GrainPool interface {
-	Process(id CartId, messages ...Message) (*FrameWithPayload, error)
-	Get(id CartId) (*FrameWithPayload, error)
-}
-
-type Ttl struct {
-	Expires time.Time
-	Grain   *CartGrain
-}
-
-type GrainLocalPool struct {
-	mu       sync.RWMutex
-	grains   map[CartId]*CartGrain
-	expiry   []Ttl
-	spawn    func(id CartId) (*CartGrain, error)
-	Ttl      time.Duration
-	PoolSize int
-}
-
-func NewGrainLocalPool(size int, ttl time.Duration, spawn func(id CartId) (*CartGrain, error)) *GrainLocalPool {
-
-	ret := &GrainLocalPool{
-		spawn:    spawn,
-		grains:   make(map[CartId]*CartGrain),
-		expiry:   make([]Ttl, 0),
-		Ttl:      ttl,
-		PoolSize: size,
-	}
-
-	cartPurge := time.NewTicker(time.Minute)
-	go func() {
-		<-cartPurge.C
-		ret.Purge()
-	}()
-	return ret
-}
-
-func (p *GrainLocalPool) SetAvailable(availableWithLastChangeUnix map[CartId]int64) {
-	p.mu.Lock()
-	defer p.mu.Unlock()
-	for id := range availableWithLastChangeUnix {
-		if _, ok := p.grains[id]; !ok {
-			p.grains[id] = nil
-			p.expiry = append(p.expiry, Ttl{
-				Expires: time.Now().Add(p.Ttl),
-				Grain:   nil,
-			})
-		}
-	}
-}
-
-func (p *GrainLocalPool) Purge() {
-	lastChangeTime := time.Now().Add(-p.Ttl)
-	keepChanged := lastChangeTime.Unix()
-	p.mu.Lock()
-	defer p.mu.Unlock()
-	for i := 0; i < len(p.expiry); i++ {
-		item := p.expiry[i]
-		if item.Expires.Before(time.Now()) {
-			if item.Grain.GetLastChange() > keepChanged {
-				log.Printf("Expired item %s changed, keeping", item.Grain.GetId())
-				if i < len(p.expiry)-1 {
-					p.expiry = append(p.expiry[:i], p.expiry[i+1:]...)
-					p.expiry = append(p.expiry, item)
-				} else {
-					p.expiry = append(p.expiry[:i], item)
-				}
-
-			} else {
-				log.Printf("Item %s expired", item.Grain.GetId())
-				delete(p.grains, item.Grain.GetId())
-				if i < len(p.expiry)-1 {
-					p.expiry = append(p.expiry[:i], p.expiry[i+1:]...)
-				} else {
-					p.expiry = p.expiry[:i]
-				}
-			}
-		} else {
-			break
-		}
-	}
-}
-
-func (p *GrainLocalPool) GetGrains() map[CartId]*CartGrain {
-	return p.grains
-}
-
-func (p *GrainLocalPool) GetGrain(id CartId) (*CartGrain, error) {
-	var err error
-	// p.mu.RLock()
-	// defer p.mu.RUnlock()
-	grain, ok := p.grains[id]
-	grainLookups.Inc()
-	if grain == nil || !ok {
-		if len(p.grains) >= p.PoolSize {
-			if p.expiry[0].Expires.Before(time.Now()) {
-				delete(p.grains, p.expiry[0].Grain.GetId())
-				p.expiry = p.expiry[1:]
-			} else {
-				return nil, fmt.Errorf("pool is full")
-			}
-		}
-		grain, err = p.spawn(id)
-		p.mu.Lock()
-		p.grains[id] = grain
-		p.mu.Unlock()
-	}
-	go func() {
-		l := float64(len(p.grains))
-		ps := float64(p.PoolSize)
-		poolUsage.Set(l / ps)
-		poolGrains.Set(l)
-		poolSize.Set(ps)
-	}()
-	return grain, err
-}
-
-func (p *GrainLocalPool) Process(id CartId, messages ...Message) (*FrameWithPayload, error) {
-	grain, err := p.GetGrain(id)
-	var result *FrameWithPayload
-	if err == nil && grain != nil {
-		for _, message := range messages {
-			result, err = grain.HandleMessage(&message, false)
-		}
-	}
-	return result, err
-}
-
-func (p *GrainLocalPool) Get(id CartId) (*FrameWithPayload, error) {
-	grain, err := p.GetGrain(id)
-	if err != nil {
-		return nil, err
-	}
-	data, err := json.Marshal(grain)
-	if err != nil {
-		return nil, err
-	}
-	ret := MakeFrameWithPayload(0, 200, data)
-	return &ret, nil
-}

id_test.go

@@ -1,19 +0,0 @@
-package main
-
-import (
-	"testing"
-)
-
-func TestIdGeneration(t *testing.T) {
-	// Generate a random ID
-	id := NewCartId()
-
-	// Generate a random ID
-	id2 := NewCartId()
-	// Compare the two IDs
-	if id == id2 {
-		t.Errorf("IDs are the same: %v == %v", id, id2)
-	} else {
-		t.Log("ID generation test passed", id, id2)
-	}
-}

k6/README.md

@@ -0,0 +1,174 @@
+# k6 Load Tests for Cart API
+
+This directory contains a k6 script (`cart_load_test.js`) to stress and observe the cart actor HTTP API.
+
+## Contents
+
+- `cart_load_test.js` – primary k6 scenario script
+- `README.md` – this file
+
+## Prerequisites
+
+- Node not required (k6 runs standalone)
+- k6 installed (>= v0.43 recommended)
+- Prometheus + Grafana (optional) if you want to correlate with the dashboard you generated
+- A running cart service exposing HTTP endpoints at (default) `http://localhost:8080/cart`
+
+## Endpoints Exercised
+
+The script exercises (per iteration):
+
+1. `GET /cart/` – ensure / fetch cart state (creates cart if missing; sets `cartid` & `cartowner` cookies)
+2. `POST /cart/` – add item mutation (random SKU & quantity)
+3. `GET /cart/` – fetch after mutations
+4. `GET /cart/checkout` – occasionally (~2% of iterations) to simulate checkout start
+
+You can extend it easily to hit deliveries, quantity changes, or removal endpoints.
+
+## Environment Variables
+
+| Variable        | Purpose                                      | Default                 |
+|-----------------|----------------------------------------------|-------------------------|
+| `BASE_URL`      | Base URL root (either host or host/cart)     | `http://localhost:8080/cart` |
+| `VUS`           | VUs for steady_mutations scenario            | `20`                    |
+| `DURATION`      | Duration for steady_mutations scenario       | `5m`                    |
+| `RAMP_TARGET`   | Peak VUs for ramp_up scenario                 | `50`                    |
+
+You can also disable one scenario by editing `options.scenarios` inside the script.
+
+Example run:
+
+```bash
+k6 run \
+  -e BASE_URL=https://cart.prod.example.com/cart \
+  -e VUS=40 \
+  -e DURATION=10m \
+  -e RAMP_TARGET=120 \
+  k6/cart_load_test.js
+```
+
+## Metrics (Custom)
+
+The script defines additional k6 metrics:
+
+- `cart_add_item_duration` (Trend) – latency of POST add item
+- `cart_fetch_duration` (Trend) – latency of GET cart state
+- `cart_checkout_duration` (Trend) – latency of checkout
+- `cart_items_added` (Counter) – successful add item operations
+- `cart_checkout_calls` (Counter) – successful checkout calls
+
+Thresholds (in `options.thresholds`) enforce basic SLO:
+- Mutation failure rate < 2%
+- p90 mutation latency < 800 ms
+- p99 overall HTTP latency < 1500 ms
+
+Adjust thresholds to your environment if they trigger prematurely.
+
+## Cookies & Stickiness
+
+The script preserves:
+- `cartid` – cart identity (server sets expiry separately)
+- `cartowner` – owning host for sticky routing
+
+If your load balancer or ingress enforces affinity based on these cookies, traffic will naturally concentrate on the originally claimed host for each cart under test.
+
+## SKU Set
+
+SKUs used (randomly selected each mutation):
+
+```
+778290 778345 778317 778277 778267 778376 778244 778384
+778365 778377 778255 778286 778246 778270 778266 778285
+778329 778425 778407 778418 778430 778469 778358 778351
+778319 778307 778278 778251 778253 778261 778263 778273
+778281 778294 778297 778302
+```
+
+To add/remove SKUs, edit the `SKUS` array. Keeping it non-empty and moderately sized helps randomization.
+
+## Extending the Script
+
+### Add Quantity Change
+
+```js
+function changeQuantity(itemId, newQty) {
+  const payload = JSON.stringify({ Id: itemId, Qty: newQty });
+  http.put(baseUrl() + '/', payload, { headers: headers() });
+}
+```
+
+### Remove Item
+
+```js
+function removeItem(itemId) {
+  http.del(baseUrl() + '/' + itemId, null, { headers: headers() });
+}
+```
+
+### Add Delivery
+
+```js
+function addDelivery(itemIds) {
+  const payload = JSON.stringify({ provider: "POSTNORD", items: itemIds });
+  http.post(baseUrl() + '/delivery', payload, { headers: headers() });
+}
+```
+
+You can integrate these into the iteration loop with probabilities.
+
+## Output Summary
+
+`handleSummary` outputs a JSON summary to stdout:
+- Average & p95 mutation latencies (if present)
+- Fetch p95
+- Checkout count
+- Check statuses
+
+Redirect or parse that output for CI pipelines.
+
+## Running in CI
+
+Use shorter durations (e.g. `DURATION=2m VUS=10`) to keep builds fast. Fail build on threshold breaches:
+
+```bash
+k6 run -e BASE_URL=$TARGET -e VUS=10 -e DURATION=2m k6/cart_load_test.js || exit 1
+```
+
+## Correlating with Prometheus / Grafana
+
+During load, observe:
+- `cart_mutations_total` growth and latency histograms
+- Event log write rate (`cart_event_log_appends_total`)
+- Pool usage (`cart_grain_pool_usage`) and spawn rate (`cart_grain_spawned_total`)
+- Failure counters (`cart_mutation_failures_total`) ensure they remain low
+
+If mutation latency spikes without high error rate, inspect external dependencies (e.g., product fetcher or Klarna endpoints).
+
+## Common Tuning Tips
+
+| Symptom                             | Potential Adjustment                              |
+|------------------------------------|---------------------------------------------------|
+| High latency p99                   | Increase CPU/memory, optimize mutation handlers   |
+| Pool at capacity                   | Raise pool size argument or TTL                   |
+| Frequent cart eviction mid-test    | Confirm TTL is sliding (now 2h on mutation)       |
+| High replay duration               | Consider snapshot + truncate event logs           |
+| Uneven host load                   | Verify `cartowner` cookie is respected upstream   |
+
+## Safety / Load Guardrails
+
+- Start with low VUs (5–10) and short duration.
+- Scale incrementally to find saturation points.
+- If using production endpoints, coordinate off-peak runs.
+
+## License / Attribution
+
+This test script is tailored for your internal cart actor system; adapt freely. k6 is open-source (AGPL v3). Ensure compliance if redistributing.
+
+---
+
+Feel free to request:
+- A variant script for spike tests
+- WebSocket / long poll integration (if added later)
+- Synthetic error injection harness
+
+Happy load testing!

k6/cart_load_test.js

@@ -0,0 +1,248 @@
+import http from "k6/http";
+import { check, sleep, group } from "k6";
+import { Counter, Trend } from "k6/metrics";
+
+// ---------------- Configuration ----------------
+export const options = {
+    // Adjust vus/duration for your environment
+    scenarios: {
+        steady_mutations: {
+            executor: "constant-vus",
+            vus: __ENV.VUS ? parseInt(__ENV.VUS, 10) : 20,
+            duration: __ENV.DURATION || "5m",
+            gracefulStop: "30s",
+        },
+        ramp_up: {
+            executor: "ramping-vus",
+            startVUs: 0,
+            stages: [
+                {
+                    duration: "1m",
+                    target: __ENV.RAMP_TARGET
+                        ? parseInt(__ENV.RAMP_TARGET, 10)
+                        : 50,
+                },
+                {
+                    duration: "1m",
+                    target: __ENV.RAMP_TARGET
+                        ? parseInt(__ENV.RAMP_TARGET, 10)
+                        : 50,
+                },
+                { duration: "1m", target: 0 },
+            ],
+            gracefulStop: "30s",
+            startTime: "30s",
+        },
+    },
+    thresholds: {
+        http_req_failed: ["rate<0.02"], // < 2% failures
+        http_req_duration: ["p(90)<800", "p(99)<1500"], // latency SLO
+        "cart_add_item_duration{op:add}": ["p(90)<800"],
+        "cart_fetch_duration{op:get}": ["p(90)<600"],
+    },
+    summaryTrendStats: ["avg", "min", "med", "max", "p(90)", "p(95)", "p(99)"],
+};
+
+// ---------------- Metrics ----------------
+const addItemTrend = new Trend("cart_add_item_duration", true);
+const fetchTrend = new Trend("cart_fetch_duration", true);
+const checkoutTrend = new Trend("cart_checkout_duration", true);
+const addedItemsCounter = new Counter("cart_items_added");
+const checkoutCounter = new Counter("cart_checkout_calls");
+
+// ---------------- SKUs ----------------
+const SKUS = [
+    "778290",
+    "778345",
+    "778317",
+    "778277",
+    "778267",
+    "778376",
+    "778244",
+    "778384",
+    "778365",
+    "778377",
+    "778255",
+    "778286",
+    "778246",
+    "778270",
+    "778266",
+    "778285",
+    "778329",
+    "778425",
+    "778407",
+    "778418",
+    "778430",
+    "778469",
+    "778358",
+    "778351",
+    "778319",
+    "778307",
+    "778278",
+    "778251",
+    "778253",
+    "778261",
+    "778263",
+    "778273",
+    "778281",
+    "778294",
+    "778297",
+    "778302",
+];
+
+// ---------------- Helpers ----------------
+function randomSku() {
+    return SKUS[Math.floor(Math.random() * SKUS.length)];
+}
+function randomQty() {
+    return 1 + Math.floor(Math.random() * 3); // 1..3
+}
+function baseUrl() {
+    const u = __ENV.BASE_URL || "http://localhost:8080/cart";
+    // Allow user to pass either root host or full /cart path
+    return u.endsWith("/cart") ? u : u.replace(/\/+$/, "") + "/cart";
+}
+function extractCookie(res, name) {
+    const cookies = res.cookies[name];
+    if (!cookies || cookies.length === 0) return null;
+    return cookies[0].value;
+}
+function withCookies(headers, cookieJar) {
+    if (!cookieJar || Object.keys(cookieJar).length === 0) return headers;
+    const cookieStr = Object.entries(cookieJar)
+        .map(([k, v]) => `${k}=${v}`)
+        .join("; ");
+    return { ...headers, Cookie: cookieStr };
+}
+
+// Maintain cart + owner cookies per VU
+let cartState = {
+    cartid: null,
+    cartowner: null,
+};
+
+// Refresh cookies from response
+function updateCookies(res) {
+    const cid = extractCookie(res, "cartid");
+    if (cid) cartState.cartid = cid;
+    const owner = extractCookie(res, "cartowner");
+    if (owner) cartState.cartowner = owner;
+}
+
+// Build headers
+function headers() {
+    const h = { "Content-Type": "application/json" };
+    const jar = {};
+    if (cartState.cartid) jar["cartid"] = cartState.cartid;
+    if (cartState.cartowner) jar["cartowner"] = cartState.cartowner;
+    return withCookies(h, jar);
+}
+
+// Ensure cart exists (GET /)
+function ensureCart() {
+    if (cartState.cartid) return;
+    const res = http.get(baseUrl() + "/", { headers: headers() });
+    updateCookies(res);
+    check(res, {
+        "ensure cart status 200": (r) => r.status === 200,
+        "ensure cart has id": () => !!cartState.cartid,
+    });
+}
+
+// Add random item
+function addRandomItem() {
+    const payload = JSON.stringify({
+        sku: randomSku(),
+        quantity: randomQty(),
+        country: "no",
+    });
+    const start = Date.now();
+    const res = http.post(baseUrl(), payload, { headers: headers() });
+    const dur = Date.now() - start;
+    addItemTrend.add(dur, { op: "add" });
+    if (res.status === 200) {
+        addedItemsCounter.add(1);
+    }
+    updateCookies(res);
+    check(res, {
+        "add item status ok": (r) => r.status === 200,
+    });
+}
+
+// Fetch cart state
+function fetchCart() {
+    const start = Date.now();
+    const res = http.get(baseUrl() + "/", { headers: headers() });
+    const dur = Date.now() - start;
+    fetchTrend.add(dur, { op: "get" });
+    updateCookies(res);
+    check(res, { "fetch status ok": (r) => r.status === 200 });
+}
+
+// Occasional checkout trigger
+function maybeCheckout() {
+    if (!cartState.cartid) return;
+    // // Small probability
+    // if (Math.random() < 0.02) {
+    //     const start = Date.now();
+    //     const res = http.get(baseUrl() + "/checkout", { headers: headers() });
+    //     const dur = Date.now() - start;
+    //     checkoutTrend.add(dur, { op: "checkout" });
+    //     updateCookies(res);
+    //     if (res.status === 200) checkoutCounter.add(1);
+    //     check(res, { "checkout status ok": (r) => r.status === 200 });
+    // }
+}
+
+// ---------------- k6 lifecycle ----------------
+export function setup() {
+    // Provide SKU list length for summary
+    return { skuCount: SKUS.length };
+}
+
+export default function (data) {
+    group("cart flow", () => {
+        // Create or reuse cart
+        ensureCart();
+
+        // Random number of item mutations per iteration (1..5)
+        const ops = 1 + Math.floor(Math.random() * 5);
+        for (let i = 0; i < ops; i++) {
+            addRandomItem();
+        }
+
+        // Fetch state
+        fetchCart();
+
+        // Optional checkout attempt
+        maybeCheckout();
+    });
+
+    // Small think time
+    sleep(Math.random() * 0.5);
+}
+
+export function teardown(data) {
+    // Optionally we could GET confirmation or clear cart cookie
+    // Not implemented for load purpose.
+    console.log(`Test complete. SKU count: ${data.skuCount}`);
+}
+
+// ---------------- Summary ----------------
+export function handleSummary(data) {
+    return {
+        stdout: JSON.stringify(
+            {
+                metrics: {
+                    mutations_avg: data.metrics.cart_add_item_duration?.avg,
+                    mutations_p95: data.metrics.cart_add_item_duration?.p(95),
+                    fetch_p95: data.metrics.cart_fetch_duration?.p(95),
+                    checkout_count: data.metrics.cart_checkout_calls?.count,
+                },
+                checks: data.root_checks,
+            },
+            null,
+            2,
+        ),
+    };
+}

main.go

@@ -1,413 +0,0 @@
-package main
-
-import (
-	"encoding/json"
-	"fmt"
-	"log"
-	"net/http"
-	"net/http/pprof"
-	"os"
-	"os/signal"
-	"strings"
-	"syscall"
-	"time"
-
-	messages "git.tornberg.me/go-cart-actor/proto"
-	"github.com/prometheus/client_golang/prometheus"
-	"github.com/prometheus/client_golang/prometheus/promauto"
-	"github.com/prometheus/client_golang/prometheus/promhttp"
-	"k8s.io/client-go/kubernetes"
-	"k8s.io/client-go/rest"
-)
-
-var (
-	grainSpawns = promauto.NewCounter(prometheus.CounterOpts{
-		Name: "cart_grain_spawned_total",
-		Help: "The total number of spawned grains",
-	})
-	grainMutations = promauto.NewCounter(prometheus.CounterOpts{
-		Name: "cart_grain_mutations_total",
-		Help: "The total number of mutations",
-	})
-	grainLookups = promauto.NewCounter(prometheus.CounterOpts{
-		Name: "cart_grain_lookups_total",
-		Help: "The total number of lookups",
-	})
-)
-
-func spawn(id CartId) (*CartGrain, error) {
-	grainSpawns.Inc()
-	ret := &CartGrain{
-		lastItemId:      0,
-		lastDeliveryId:  0,
-		Deliveries:      []*CartDelivery{},
-		Id:              id,
-		Items:           []*CartItem{},
-		storageMessages: []Message{},
-		TotalPrice:      0,
-	}
-	err := loadMessages(ret, id)
-	return ret, err
-}
-
-func init() {
-	os.Mkdir("data", 0755)
-}
-
-type App struct {
-	pool    *GrainLocalPool
-	storage *DiskStorage
-}
-
-func (a *App) Save() error {
-	hasChanges := false
-	a.pool.mu.RLock()
-	defer a.pool.mu.RUnlock()
-	for id, grain := range a.pool.GetGrains() {
-		if grain == nil {
-			continue
-		}
-		if grain.GetLastChange() > a.storage.LastSaves[id] {
-			hasChanges = true
-			err := a.storage.Store(id, grain)
-			if err != nil {
-				log.Printf("Error saving grain %s: %v\n", id, err)
-			}
-		}
-	}
-
-	if !hasChanges {
-		return nil
-	}
-	return a.storage.saveState()
-}
-
-func (a *App) HandleSave(w http.ResponseWriter, r *http.Request) {
-	err := a.Save()
-	if err != nil {
-		w.WriteHeader(http.StatusInternalServerError)
-		w.Write([]byte(err.Error()))
-	} else {
-		w.WriteHeader(http.StatusCreated)
-	}
-}
-
-var podIp = os.Getenv("POD_IP")
-var name = os.Getenv("POD_NAME")
-var amqpUrl = os.Getenv("AMQP_URL")
-var KlarnaInstance = NewKlarnaClient(KlarnaPlaygroundUrl, os.Getenv("KLARNA_API_USERNAME"), os.Getenv("KLARNA_API_PASSWORD"))
-
-func GetDiscovery() Discovery {
-	if podIp == "" {
-		return nil
-	}
-
-	config, kerr := rest.InClusterConfig()
-
-	if kerr != nil {
-		log.Fatalf("Error creating kubernetes client: %v\n", kerr)
-	}
-	client, err := kubernetes.NewForConfig(config)
-	if err != nil {
-		log.Fatalf("Error creating client: %v\n", err)
-	}
-	return NewK8sDiscovery(client)
-}
-
-var tpl = `<!DOCTYPE html>
-<html lang="en">
-  <head>
-    <meta charset="UTF-8" />
-    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
-    <title>s10r testing - checkout</title>
-  </head>
-
-  <body>
-    %s
-  </body>
-</html>
-`
-
-func getCountryFromHost(host string) string {
-	if strings.Contains(strings.ToLower(host), "-no") {
-		return "no"
-	}
-	return "se"
-}
-
-func getCheckoutOrder(host string, cartId CartId) *messages.CreateCheckoutOrder {
-	baseUrl := fmt.Sprintf("https://%s", host)
-	cartBaseUrl := os.Getenv("CART_BASE_URL")
-	if cartBaseUrl == "" {
-		cartBaseUrl = "https://cart.tornberg.me"
-	}
-	country := getCountryFromHost(host)
-
-	return &messages.CreateCheckoutOrder{
-		Terms:        fmt.Sprintf("%s/terms", baseUrl),
-		Checkout:     fmt.Sprintf("%s/checkout?order_id={checkout.order.id}", baseUrl),
-		Confirmation: fmt.Sprintf("%s/confirmation/{checkout.order.id}", baseUrl),
-		Validation:   fmt.Sprintf("%s/validation", cartBaseUrl),
-		Push:         fmt.Sprintf("%s/push?order_id={checkout.order.id}", cartBaseUrl),
-		Country:      country,
-	}
-}
-
-func main() {
-
-	storage, err := NewDiskStorage(fmt.Sprintf("data/%s_state.gob", name))
-	if err != nil {
-		log.Printf("Error loading state: %v\n", err)
-	}
-	app := &App{
-		pool:    NewGrainLocalPool(65535, 5*time.Minute, spawn),
-		storage: storage,
-	}
-
-	syncedPool, err := NewSyncedPool(app.pool, podIp, GetDiscovery())
-	if err != nil {
-		log.Fatalf("Error creating synced pool: %v\n", err)
-	}
-
-	hg, err := NewGrainHandler(app.pool, ":1337")
-	if err != nil {
-		log.Fatalf("Error creating handler: %v\n", err)
-	}
-
-	go func() {
-		for range time.Tick(time.Minute * 10) {
-			err := app.Save()
-			if err != nil {
-				log.Printf("Error saving: %v\n", err)
-			}
-		}
-	}()
-	orderHandler := &AmqpOrderHandler{
-		Url: amqpUrl,
-	}
-
-	syncedServer := NewPoolServer(syncedPool, fmt.Sprintf("%s, %s", name, podIp))
-	mux := http.NewServeMux()
-	mux.Handle("/cart/", http.StripPrefix("/cart", syncedServer.Serve()))
-	// only for local
-	// mux.HandleFunc("GET /add/remote/{host}", func(w http.ResponseWriter, r *http.Request) {
-	// 	syncedPool.AddRemote(r.PathValue("host"))
-	// })
-	// mux.HandleFunc("GET /save", app.HandleSave)
-	//mux.HandleFunc("/", app.RewritePath)
-	mux.HandleFunc("/debug/pprof/", pprof.Index)
-	mux.HandleFunc("/debug/pprof/cmdline", pprof.Cmdline)
-	mux.HandleFunc("/debug/pprof/profile", pprof.Profile)
-	mux.HandleFunc("/debug/pprof/symbol", pprof.Symbol)
-	mux.HandleFunc("/debug/pprof/trace", pprof.Trace)
-	mux.Handle("/metrics", promhttp.Handler())
-	mux.HandleFunc("/healthz", func(w http.ResponseWriter, r *http.Request) {
-		if !hg.IsHealthy() {
-			w.WriteHeader(http.StatusInternalServerError)
-			w.Write([]byte("handler not healthy"))
-			return
-		}
-		if !syncedPool.IsHealthy() {
-			w.WriteHeader(http.StatusInternalServerError)
-			w.Write([]byte("pool not healthy"))
-			return
-		}
-
-		w.WriteHeader(http.StatusOK)
-		w.Write([]byte("ok"))
-	})
-	mux.HandleFunc("/readyz", func(w http.ResponseWriter, r *http.Request) {
-		w.WriteHeader(http.StatusOK)
-		w.Write([]byte("ok"))
-	})
-	mux.HandleFunc("/livez", func(w http.ResponseWriter, r *http.Request) {
-		w.WriteHeader(http.StatusOK)
-		w.Write([]byte("ok"))
-	})
-
-	mux.HandleFunc("/checkout", func(w http.ResponseWriter, r *http.Request) {
-		orderId := r.URL.Query().Get("order_id")
-		order := &CheckoutOrder{}
-
-		if orderId == "" {
-			cookie, err := r.Cookie("cartid")
-			if err != nil {
-				w.WriteHeader(http.StatusBadRequest)
-				w.Write([]byte(err.Error()))
-				return
-			}
-			if cookie.Value == "" {
-				w.WriteHeader(http.StatusBadRequest)
-				w.Write([]byte("no cart id to checkout is empty"))
-				return
-			}
-			cartId := ToCartId(cookie.Value)
-			reply, err := syncedServer.pool.Process(cartId, Message{
-				Type:    CreateCheckoutOrderType,
-				Content: getCheckoutOrder(r.Host, cartId),
-			})
-			if err != nil {
-				w.WriteHeader(http.StatusInternalServerError)
-				w.Write([]byte(err.Error()))
-			}
-			err = json.Unmarshal(reply.Payload, &order)
-			if err != nil {
-				w.WriteHeader(http.StatusInternalServerError)
-				w.Write([]byte(err.Error()))
-				return
-			}
-		} else {
-			prevOrder, err := KlarnaInstance.GetOrder(orderId)
-			if err != nil {
-				w.WriteHeader(http.StatusBadRequest)
-				w.Write([]byte(err.Error()))
-				return
-			}
-			order = prevOrder
-		}
-		w.Header().Set("Content-Type", "text/html; charset=utf-8")
-		w.Header().Set("Permissions-Policy", "payment=(self \"https://js.stripe.com\" \"https://m.stripe.network\" \"https://js.playground.kustom.co\")")
-		w.WriteHeader(http.StatusOK)
-		w.Write([]byte(fmt.Sprintf(tpl, order.HTMLSnippet)))
-	})
-	mux.HandleFunc("/confirmation/{order_id}", func(w http.ResponseWriter, r *http.Request) {
-
-		orderId := r.PathValue("order_id")
-		order, err := KlarnaInstance.GetOrder(orderId)
-
-		if err != nil {
-			w.WriteHeader(http.StatusInternalServerError)
-			w.Write([]byte(err.Error()))
-			return
-		}
-
-		w.Header().Set("Content-Type", "text/html; charset=utf-8")
-		if order.Status == "checkout_complete" {
-			http.SetCookie(w, &http.Cookie{
-				Name:     "cartid",
-				Value:    "",
-				Path:     "/",
-				Secure:   true,
-				HttpOnly: true,
-				Expires:  time.Unix(0, 0),
-				SameSite: http.SameSiteLaxMode,
-			})
-		}
-
-		w.WriteHeader(http.StatusOK)
-		w.Write([]byte(fmt.Sprintf(tpl, order.HTMLSnippet)))
-	})
-	mux.HandleFunc("/validate", func(w http.ResponseWriter, r *http.Request) {
-		log.Printf("Klarna order validation, method: %s", r.Method)
-		if r.Method != "POST" {
-			w.WriteHeader(http.StatusMethodNotAllowed)
-			return
-		}
-		order := &CheckoutOrder{}
-		err := json.NewDecoder(r.Body).Decode(order)
-		if err != nil {
-			w.WriteHeader(http.StatusBadRequest)
-		}
-		log.Printf("Klarna order validation: %s", order.ID)
-		//err = confirmOrder(order, orderHandler)
-		//if err != nil {
-		//	log.Printf("Error validating order: %v\n", err)
-		//	w.WriteHeader(http.StatusInternalServerError)
-		//	return
-		//}
-		//
-		//err = triggerOrderCompleted(err, syncedServer, order)
-		//if err != nil {
-		//	log.Printf("Error processing cart message: %v\n", err)
-		//	w.WriteHeader(http.StatusInternalServerError)
-		//	return
-		//}
-		w.WriteHeader(http.StatusOK)
-	})
-	mux.HandleFunc("/push", func(w http.ResponseWriter, r *http.Request) {
-
-		if r.Method != http.MethodPost {
-			w.WriteHeader(http.StatusMethodNotAllowed)
-			return
-		}
-		orderId := r.URL.Query().Get("order_id")
-		log.Printf("Order confirmation push: %s", orderId)
-
-		order, err := KlarnaInstance.GetOrder(orderId)
-
-		if err != nil {
-			log.Printf("Error creating request: %v\n", err)
-			w.WriteHeader(http.StatusInternalServerError)
-			return
-		}
-
-		err = confirmOrder(order, orderHandler)
-		if err != nil {
-			log.Printf("Error confirming order: %v\n", err)
-			w.WriteHeader(http.StatusInternalServerError)
-			return
-		}
-
-		err = triggerOrderCompleted(err, syncedServer, order)
-		if err != nil {
-			log.Printf("Error processing cart message: %v\n", err)
-			w.WriteHeader(http.StatusInternalServerError)
-			return
-		}
-		err = KlarnaInstance.AcknowledgeOrder(orderId)
-		if err != nil {
-			log.Printf("Error acknowledging order: %v\n", err)
-		}
-
-		w.WriteHeader(http.StatusOK)
-	})
-	mux.HandleFunc("/version", func(w http.ResponseWriter, r *http.Request) {
-		w.WriteHeader(http.StatusOK)
-		w.Write([]byte("1.0.0"))
-	})
-
-	sigs := make(chan os.Signal, 1)
-	done := make(chan bool, 1)
-	signal.Notify(sigs, syscall.SIGTERM)
-
-	go func() {
-		sig := <-sigs
-		fmt.Println("Shutting down due to signal:", sig)
-		go syncedPool.Close()
-		app.Save()
-		done <- true
-	}()
-
-	go http.ListenAndServe(":8080", mux)
-	<-done
-
-}
-
-func triggerOrderCompleted(err error, syncedServer *PoolServer, order *CheckoutOrder) error {
-	_, err = syncedServer.pool.Process(ToCartId(order.MerchantReference1), Message{
-		Type: OrderCompletedType,
-		Content: &messages.OrderCreated{
-			OrderId: order.ID,
-			Status:  order.Status,
-		},
-	})
-	return err
-}
-
-func confirmOrder(order *CheckoutOrder, orderHandler *AmqpOrderHandler) error {
-	orderToSend, err := json.Marshal(order)
-	if err != nil {
-		return err
-	}
-	err = orderHandler.Connect()
-	if err != nil {
-		return err
-	}
-	defer orderHandler.Close()
-	err = orderHandler.OrderCompleted(orderToSend)
-	if err != nil {
-		return err
-	}
-
-	return nil
-}

main_test.go

@@ -1,286 +0,0 @@
-package main
-
-import (
-	"os"
-	"testing"
-)
-
-func TestGetCountryFromHost(t *testing.T) {
-	tests := []struct {
-		name     string
-		host     string
-		expected string
-	}{
-		{
-			name:     "Norwegian host",
-			host:     "s10n-no.tornberg.me",
-			expected: "no",
-		},
-		{
-			name:     "Swedish host",
-			host:     "s10n-se.tornberg.me",
-			expected: "se",
-		},
-		{
-			name:     "Host with -no in the middle",
-			host:     "api-no-staging.tornberg.me",
-			expected: "no",
-		},
-		{
-			name:     "Host without country suffix",
-			host:     "s10n.tornberg.me",
-			expected: "se",
-		},
-		{
-			name:     "Host with different domain",
-			host:     "example-no.com",
-			expected: "no",
-		},
-		{
-			name:     "Empty host",
-			host:     "",
-			expected: "se",
-		},
-		{
-			name:     "Host with uppercase",
-			host:     "S10N-NO.TORNBERG.ME",
-			expected: "no",
-		},
-		{
-			name:     "Host with mixed case",
-			host:     "S10n-No.Tornberg.Me",
-			expected: "no",
-		},
-	}
-
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			result := getCountryFromHost(tt.host)
-			if result != tt.expected {
-				t.Errorf("getCountryFromHost(%q) = %q, want %q", tt.host, result, tt.expected)
-			}
-		})
-	}
-}
-
-func TestGetCheckoutOrder(t *testing.T) {
-	// Save original environment variable and restore after test
-	originalCartBaseUrl := os.Getenv("CART_BASE_URL")
-	defer func() {
-		if originalCartBaseUrl == "" {
-			os.Unsetenv("CART_BASE_URL")
-		} else {
-			os.Setenv("CART_BASE_URL", originalCartBaseUrl)
-		}
-	}()
-
-	tests := []struct {
-		name         string
-		host         string
-		cartId       CartId
-		cartBaseUrl  string
-		expectedUrls struct {
-			terms        string
-			checkout     string
-			confirmation string
-			validation   string
-			push         string
-			country      string
-		}
-	}{
-		{
-			name:        "Norwegian host with default cart base URL",
-			host:        "s10n-no.tornberg.me",
-			cartId:      ToCartId("test-cart-123"),
-			cartBaseUrl: "", // Use default
-			expectedUrls: struct {
-				terms        string
-				checkout     string
-				confirmation string
-				validation   string
-				push         string
-				country      string
-			}{
-				terms:        "https://s10n-no.tornberg.me/terms",
-				checkout:     "https://s10n-no.tornberg.me/checkout?order_id={checkout.order.id}",
-				confirmation: "https://s10n-no.tornberg.me/confirmation/{checkout.order.id}",
-				validation:   "https://cart.tornberg.me/validation",
-				push:         "https://cart.tornberg.me/push?order_id={checkout.order.id}",
-				country:      "no",
-			},
-		},
-		{
-			name:        "Swedish host with default cart base URL",
-			host:        "s10n-se.tornberg.me",
-			cartId:      ToCartId("test-cart-456"),
-			cartBaseUrl: "", // Use default
-			expectedUrls: struct {
-				terms        string
-				checkout     string
-				confirmation string
-				validation   string
-				push         string
-				country      string
-			}{
-				terms:        "https://s10n-se.tornberg.me/terms",
-				checkout:     "https://s10n-se.tornberg.me/checkout?order_id={checkout.order.id}",
-				confirmation: "https://s10n-se.tornberg.me/confirmation/{checkout.order.id}",
-				validation:   "https://cart.tornberg.me/validation",
-				push:         "https://cart.tornberg.me/push?order_id={checkout.order.id}",
-				country:      "se",
-			},
-		},
-		{
-			name:        "Norwegian host with custom cart base URL",
-			host:        "s10n-no.tornberg.me",
-			cartId:      ToCartId("test-cart-789"),
-			cartBaseUrl: "https://custom-cart.example.com",
-			expectedUrls: struct {
-				terms        string
-				checkout     string
-				confirmation string
-				validation   string
-				push         string
-				country      string
-			}{
-				terms:        "https://s10n-no.tornberg.me/terms",
-				checkout:     "https://s10n-no.tornberg.me/checkout?order_id={checkout.order.id}",
-				confirmation: "https://s10n-no.tornberg.me/confirmation/{checkout.order.id}",
-				validation:   "https://custom-cart.example.com/validation",
-				push:         "https://custom-cart.example.com/push?order_id={checkout.order.id}",
-				country:      "no",
-			},
-		},
-		{
-			name:        "Host without country code defaults to Swedish",
-			host:        "s10n.tornberg.me",
-			cartId:      ToCartId("test-cart-default"),
-			cartBaseUrl: "",
-			expectedUrls: struct {
-				terms        string
-				checkout     string
-				confirmation string
-				validation   string
-				push         string
-				country      string
-			}{
-				terms:        "https://s10n.tornberg.me/terms",
-				checkout:     "https://s10n.tornberg.me/checkout?order_id={checkout.order.id}",
-				confirmation: "https://s10n.tornberg.me/confirmation/{checkout.order.id}",
-				validation:   "https://cart.tornberg.me/validation",
-				push:         "https://cart.tornberg.me/push?order_id={checkout.order.id}",
-				country:      "se",
-			},
-		},
-	}
-
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			// Set up environment variable for this test
-			if tt.cartBaseUrl == "" {
-				os.Unsetenv("CART_BASE_URL")
-			} else {
-				os.Setenv("CART_BASE_URL", tt.cartBaseUrl)
-			}
-
-			result := getCheckoutOrder(tt.host, tt.cartId)
-
-			// Verify the result is not nil
-			if result == nil {
-				t.Fatal("getCheckoutOrder returned nil")
-			}
-
-			// Check each URL field
-			if result.Terms != tt.expectedUrls.terms {
-				t.Errorf("Terms URL: got %q, want %q", result.Terms, tt.expectedUrls.terms)
-			}
-
-			if result.Checkout != tt.expectedUrls.checkout {
-				t.Errorf("Checkout URL: got %q, want %q", result.Checkout, tt.expectedUrls.checkout)
-			}
-
-			if result.Confirmation != tt.expectedUrls.confirmation {
-				t.Errorf("Confirmation URL: got %q, want %q", result.Confirmation, tt.expectedUrls.confirmation)
-			}
-
-			if result.Validation != tt.expectedUrls.validation {
-				t.Errorf("Validation URL: got %q, want %q", result.Validation, tt.expectedUrls.validation)
-			}
-
-			if result.Push != tt.expectedUrls.push {
-				t.Errorf("Push URL: got %q, want %q", result.Push, tt.expectedUrls.push)
-			}
-
-			if result.Country != tt.expectedUrls.country {
-				t.Errorf("Country: got %q, want %q", result.Country, tt.expectedUrls.country)
-			}
-		})
-	}
-}
-
-func TestGetCheckoutOrderIntegration(t *testing.T) {
-	// Test that both functions work together correctly
-	hosts := []string{"s10n-no.tornberg.me", "s10n-se.tornberg.me"}
-	cartId := ToCartId("integration-test-cart")
-
-	for _, host := range hosts {
-		t.Run(host, func(t *testing.T) {
-			// Get country from host
-			country := getCountryFromHost(host)
-
-			// Get checkout order
-			order := getCheckoutOrder(host, cartId)
-
-			// Verify that the country in the order matches what getCountryFromHost returns
-			if order.Country != country {
-				t.Errorf("Country mismatch: getCountryFromHost(%q) = %q, but order.Country = %q",
-					host, country, order.Country)
-			}
-
-			// Verify that all URLs contain the correct host
-			expectedBaseUrl := "https://" + host
-
-			if !containsPrefix(order.Terms, expectedBaseUrl) {
-				t.Errorf("Terms URL should start with %q, got %q", expectedBaseUrl, order.Terms)
-			}
-
-			if !containsPrefix(order.Checkout, expectedBaseUrl) {
-				t.Errorf("Checkout URL should start with %q, got %q", expectedBaseUrl, order.Checkout)
-			}
-
-			if !containsPrefix(order.Confirmation, expectedBaseUrl) {
-				t.Errorf("Confirmation URL should start with %q, got %q", expectedBaseUrl, order.Confirmation)
-			}
-		})
-	}
-}
-
-// Helper function to check if a string starts with a prefix
-func containsPrefix(s, prefix string) bool {
-	return len(s) >= len(prefix) && s[:len(prefix)] == prefix
-}
-
-// Benchmark tests to measure performance
-func BenchmarkGetCountryFromHost(b *testing.B) {
-	hosts := []string{
-		"s10n-no.tornberg.me",
-		"s10n-se.tornberg.me",
-		"api-no-staging.tornberg.me",
-		"s10n.tornberg.me",
-	}
-
-	for i := 0; i < b.N; i++ {
-		for _, host := range hosts {
-			getCountryFromHost(host)
-		}
-	}
-}
-
-func BenchmarkGetCheckoutOrder(b *testing.B) {
-	host := "s10n-no.tornberg.me"
-	cartId := ToCartId("benchmark-cart")
-
-	for i := 0; i < b.N; i++ {
-		getCheckoutOrder(host, cartId)
-	}
-}

message-handler.go

@@ -1,315 +0,0 @@
-package main
-
-import (
-	"fmt"
-	"io"
-
-	messages "git.tornberg.me/go-cart-actor/proto"
-	"google.golang.org/protobuf/proto"
-)
-
-var Handlers = map[uint16]MessageHandler{
-	AddRequestType:          &AddRequestHandler{},
-	AddItemType:             &AddItemHandler{},
-	ChangeQuantityType:      &ChangeQuantityHandler{},
-	SetDeliveryType:         &SetDeliveryHandler{},
-	RemoveItemType:          &RemoveItemHandler{},
-	RemoveDeliveryType:      &RemoveDeliveryHandler{},
-	CreateCheckoutOrderType: &CheckoutHandler{},
-	SetCartItemsType:        &SetCartItemsHandler{},
-	OrderCompletedType:      &OrderCompletedHandler{},
-}
-
-func GetMessageHandler(t uint16) (MessageHandler, error) {
-	h, ok := Handlers[t]
-	if !ok {
-		return nil, fmt.Errorf("no handler for message type %d", t)
-	}
-	return h, nil
-}
-
-type MessageHandler interface {
-	Write(*Message, io.Writer) error
-	Read(data []byte) (interface{}, error)
-	Is(*Message) bool
-}
-type TypedMessageHandler struct {
-	Type uint16
-}
-
-type SetCartItemsHandler struct {
-	TypedMessageHandler
-}
-
-func (h *SetCartItemsHandler) Write(m *Message, w io.Writer) error {
-	messageBytes, err := proto.Marshal(m.Content.(*messages.SetCartRequest))
-	if err != nil {
-		return err
-	}
-	w.Write(messageBytes)
-	return nil
-}
-
-func (h *SetCartItemsHandler) Read(data []byte) (interface{}, error) {
-	msg := &messages.SetCartRequest{}
-
-	err := proto.Unmarshal(data, msg)
-	if err != nil {
-		return nil, err
-	}
-	return msg, nil
-}
-
-func (h *SetCartItemsHandler) Is(m *Message) bool {
-	if m.Type != AddRequestType {
-		return false
-	}
-	_, ok := m.Content.(*messages.SetCartRequest)
-	return ok
-}
-
-type AddRequestHandler struct {
-	TypedMessageHandler
-}
-
-func (h *AddRequestHandler) Write(m *Message, w io.Writer) error {
-	messageBytes, err := proto.Marshal(m.Content.(*messages.AddRequest))
-	if err != nil {
-		return err
-	}
-	w.Write(messageBytes)
-	return nil
-}
-
-func (h *AddRequestHandler) Read(data []byte) (interface{}, error) {
-	msg := &messages.AddRequest{}
-
-	err := proto.Unmarshal(data, msg)
-	if err != nil {
-		return nil, err
-	}
-	return msg, nil
-}
-
-func (h *AddRequestHandler) Is(m *Message) bool {
-	if m.Type != AddRequestType {
-		return false
-	}
-	_, ok := m.Content.(*messages.AddRequest)
-	return ok
-}
-
-type AddItemHandler struct {
-	TypedMessageHandler
-}
-
-func (h *AddItemHandler) Write(m *Message, w io.Writer) error {
-	messageBytes, err := proto.Marshal(m.Content.(*messages.AddItem))
-	if err != nil {
-		return err
-	}
-	w.Write(messageBytes)
-	return nil
-}
-
-func (h *AddItemHandler) Read(data []byte) (interface{}, error) {
-	msg := &messages.AddItem{}
-
-	err := proto.Unmarshal(data, msg)
-	if err != nil {
-		return nil, err
-	}
-	return msg, nil
-}
-
-func (h *AddItemHandler) Is(m *Message) bool {
-	if m.Type != AddItemType {
-		return false
-	}
-	_, ok := m.Content.(*messages.AddItem)
-	return ok
-}
-
-type ChangeQuantityHandler struct {
-	TypedMessageHandler
-}
-
-func (h *ChangeQuantityHandler) Write(m *Message, w io.Writer) error {
-	messageBytes, err := proto.Marshal(m.Content.(*messages.ChangeQuantity))
-	if err != nil {
-		return err
-	}
-	w.Write(messageBytes)
-	return nil
-}
-
-func (h *ChangeQuantityHandler) Read(data []byte) (interface{}, error) {
-	msg := &messages.ChangeQuantity{}
-
-	err := proto.Unmarshal(data, msg)
-	if err != nil {
-		return nil, err
-	}
-	return msg, nil
-}
-
-func (h *ChangeQuantityHandler) Is(m *Message) bool {
-	if m.Type != ChangeQuantityType {
-		return false
-	}
-	_, ok := m.Content.(*messages.ChangeQuantity)
-	return ok
-}
-
-type SetDeliveryHandler struct {
-	TypedMessageHandler
-}
-
-func (h *SetDeliveryHandler) Write(m *Message, w io.Writer) error {
-	messageBytes, err := proto.Marshal(m.Content.(*messages.SetDelivery))
-	if err != nil {
-		return err
-	}
-	w.Write(messageBytes)
-	return nil
-}
-
-func (h *SetDeliveryHandler) Read(data []byte) (interface{}, error) {
-	msg := &messages.SetDelivery{}
-
-	err := proto.Unmarshal(data, msg)
-	if err != nil {
-		return nil, err
-	}
-	return msg, nil
-}
-
-func (h *SetDeliveryHandler) Is(m *Message) bool {
-	if m.Type != ChangeQuantityType {
-		return false
-	}
-	_, ok := m.Content.(*messages.SetDelivery)
-	return ok
-}
-
-type RemoveItemHandler struct {
-	TypedMessageHandler
-}
-
-func (h *RemoveItemHandler) Write(m *Message, w io.Writer) error {
-	messageBytes, err := proto.Marshal(m.Content.(*messages.RemoveItem))
-	if err != nil {
-		return err
-	}
-	w.Write(messageBytes)
-	return nil
-}
-
-func (h *RemoveItemHandler) Read(data []byte) (interface{}, error) {
-	msg := &messages.RemoveItem{}
-
-	err := proto.Unmarshal(data, msg)
-	if err != nil {
-		return nil, err
-	}
-	return msg, nil
-}
-
-func (h *RemoveItemHandler) Is(m *Message) bool {
-	if m.Type != AddItemType {
-		return false
-	}
-	_, ok := m.Content.(*messages.RemoveItem)
-	return ok
-}
-
-type RemoveDeliveryHandler struct {
-	TypedMessageHandler
-}
-
-func (h *RemoveDeliveryHandler) Write(m *Message, w io.Writer) error {
-	messageBytes, err := proto.Marshal(m.Content.(*messages.RemoveDelivery))
-	if err != nil {
-		return err
-	}
-	w.Write(messageBytes)
-	return nil
-}
-
-func (h *RemoveDeliveryHandler) Read(data []byte) (interface{}, error) {
-	msg := &messages.RemoveDelivery{}
-
-	err := proto.Unmarshal(data, msg)
-	if err != nil {
-		return nil, err
-	}
-	return msg, nil
-}
-
-func (h *RemoveDeliveryHandler) Is(m *Message) bool {
-	if m.Type != AddItemType {
-		return false
-	}
-	_, ok := m.Content.(*messages.RemoveDelivery)
-	return ok
-}
-
-type CheckoutHandler struct {
-	TypedMessageHandler
-}
-
-func (h *CheckoutHandler) Write(m *Message, w io.Writer) error {
-	messageBytes, err := proto.Marshal(m.Content.(*messages.CreateCheckoutOrder))
-	if err != nil {
-		return err
-	}
-	w.Write(messageBytes)
-	return nil
-}
-
-func (h *CheckoutHandler) Read(data []byte) (interface{}, error) {
-	msg := &messages.CreateCheckoutOrder{}
-
-	err := proto.Unmarshal(data, msg)
-	if err != nil {
-		return nil, err
-	}
-	return msg, nil
-}
-
-func (h *CheckoutHandler) Is(m *Message) bool {
-	if m.Type != CreateCheckoutOrderType {
-		return false
-	}
-	_, ok := m.Content.(*messages.CreateCheckoutOrder)
-	return ok
-}
-
-type OrderCompletedHandler struct {
-	TypedMessageHandler
-}
-
-func (h *OrderCompletedHandler) Write(m *Message, w io.Writer) error {
-	messageBytes, err := proto.Marshal(m.Content.(*messages.OrderCreated))
-	if err != nil {
-		return err
-	}
-	w.Write(messageBytes)
-	return nil
-}
-func (h *OrderCompletedHandler) Read(data []byte) (interface{}, error) {
-	msg := &messages.OrderCreated{}
-
-	err := proto.Unmarshal(data, msg)
-	if err != nil {
-		return nil, err
-	}
-	return msg, nil
-}
-func (h *OrderCompletedHandler) Is(m *Message) bool {
-	if m.Type != OrderCompletedType {
-		return false
-	}
-	_, ok := m.Content.(*messages.OrderCreated)
-	return ok
-}

message-handler_test.go

@@ -1,129 +0,0 @@
-package main
-
-import (
-	"bytes"
-	"testing"
-
-	messages "git.tornberg.me/go-cart-actor/proto"
-)
-
-func TestAddRequest(t *testing.T) {
-	h, err := GetMessageHandler(AddRequestType)
-	if err != nil {
-		t.Errorf("Error getting message handler: %v\n", err)
-	}
-	if h == nil {
-		t.Errorf("Expected message handler, got nil\n")
-	}
-	message := Message{
-		Type: AddRequestType,
-		Content: &messages.AddRequest{
-			Quantity: 2,
-			Sku:      "123",
-		},
-	}
-	var b bytes.Buffer
-	err = h.Write(&message, &b)
-	if err != nil {
-		t.Errorf("Error writing message: %v\n", err)
-	}
-	result, err := h.Read(b.Bytes())
-	if err != nil {
-		t.Errorf("Error reading message: %v\n", err)
-	}
-	if result == nil {
-		t.Errorf("Expected result, got nil\n")
-	}
-	r, ok := result.(*messages.AddRequest)
-	if !ok {
-		t.Errorf("Expected AddRequest, got %T\n", result)
-	}
-	if r.Quantity != 2 {
-		t.Errorf("Expected quantity 2, got %d\n", r.Quantity)
-	}
-	if r.Sku != "123" {
-		t.Errorf("Expected sku '123', got %s\n", r.Sku)
-	}
-}
-
-func TestItemRequest(t *testing.T) {
-	h, err := GetMessageHandler(AddItemType)
-	if err != nil {
-		t.Errorf("Error getting message handler: %v\n", err)
-	}
-	if h == nil {
-		t.Errorf("Expected message handler, got nil\n")
-	}
-	message := Message{
-		Type: AddItemType,
-		Content: &messages.AddItem{
-			Quantity: 2,
-			Sku:      "123",
-			Price:    100,
-			Name:     "Test item",
-			Image:    "test.jpg",
-		},
-	}
-	var b bytes.Buffer
-	err = h.Write(&message, &b)
-	if err != nil {
-		t.Errorf("Error writing message: %v\n", err)
-	}
-	result, err := h.Read(b.Bytes())
-	if err != nil {
-		t.Errorf("Error reading message: %v\n", err)
-	}
-	if result == nil {
-		t.Errorf("Expected result, got nil\n")
-	}
-	var r *messages.AddItem
-	ok := h.Is(&message)
-	if !ok {
-		t.Errorf("Expected AddRequest, got %T\n", result)
-	}
-	if r.Quantity != 2 {
-		t.Errorf("Expected quantity 2, got %d\n", r.Quantity)
-	}
-	if r.Sku != "123" {
-		t.Errorf("Expected sku '123', got %s\n", r.Sku)
-	}
-}
-
-func TestSetDeliveryMssage(t *testing.T) {
-	h, err := GetMessageHandler(SetDeliveryType)
-	if err != nil {
-		t.Errorf("Error getting message handler: %v\n", err)
-	}
-	if h == nil {
-		t.Errorf("Expected message handler, got nil\n")
-	}
-	message := Message{
-		Type: SetDeliveryType,
-		Content: &messages.SetDelivery{
-			Provider: "test",
-			Items:    []int64{1, 2},
-		},
-	}
-	var b bytes.Buffer
-	err = h.Write(&message, &b)
-	if err != nil {
-		t.Errorf("Error writing message: %v\n", err)
-	}
-	result, err := h.Read(b.Bytes())
-	if err != nil {
-		t.Errorf("Error reading message: %v\n", err)
-	}
-	if result == nil {
-		t.Errorf("Expected result, got nil\n")
-	}
-	r, ok := result.(*messages.SetDelivery)
-	if !ok {
-		t.Errorf("Expected AddRequest, got %T\n", result)
-	}
-	if len(r.Items) != 2 {
-		t.Errorf("Expected 2 items, got %d\n", len(r.Items))
-	}
-	if r.Provider != "test" {
-		t.Errorf("Expected provider 'test', got %s\n", r.Provider)
-	}
-}

message-types.go

@@ -1,15 +0,0 @@
-package main
-
-const (
-	AddRequestType = 1
-	AddItemType    = 2
-
-	RemoveItemType          = 4
-	RemoveDeliveryType      = 5
-	ChangeQuantityType      = 6
-	SetDeliveryType         = 7
-	SetPickupPointType      = 8
-	CreateCheckoutOrderType = 9
-	SetCartItemsType        = 10
-	OrderCompletedType      = 11
-)

message.go

@@ -1,94 +0,0 @@
-package main
-
-import (
-	"bytes"
-	"encoding/binary"
-	"io"
-	"time"
-)
-
-type StorableMessage interface {
-	Write(w io.Writer) error
-}
-
-type Message struct {
-	Type      uint16
-	TimeStamp *int64
-	Content   interface{}
-}
-
-type MessageWriter struct {
-	io.Writer
-}
-
-type StorableMessageHeader struct {
-	Version    uint16
-	Type       uint16
-	TimeStamp  int64
-	DataLength uint64
-}
-
-func GetData(fn func(w io.Writer) error) ([]byte, error) {
-	var buf bytes.Buffer
-	err := fn(&buf)
-	if err != nil {
-		return nil, err
-	}
-	b := buf.Bytes()
-	return b, nil
-}
-
-func (m Message) Write(w io.Writer) error {
-	h, err := GetMessageHandler(m.Type)
-	if err != nil {
-		return err
-	}
-	data, err := GetData(func(w io.Writer) error {
-		return h.Write(&m, w)
-	})
-	if err != nil {
-		return err
-	}
-	ts := time.Now().Unix()
-	if m.TimeStamp != nil {
-		ts = *m.TimeStamp
-	}
-
-	err = binary.Write(w, binary.LittleEndian, StorableMessageHeader{
-		Version:    1,
-		Type:       m.Type,
-		TimeStamp:  ts,
-		DataLength: uint64(len(data)),
-	})
-	w.Write(data)
-
-	return err
-}
-
-func ReadMessage(reader io.Reader, m *Message) error {
-
-	header := StorableMessageHeader{}
-	err := binary.Read(reader, binary.LittleEndian, &header)
-	if err != nil {
-		return err
-	}
-	messageBytes := make([]byte, header.DataLength)
-	_, err = reader.Read(messageBytes)
-	if err != nil {
-		return err
-	}
-	h, err := GetMessageHandler(header.Type)
-	if err != nil {
-		return err
-	}
-	content, err := h.Read(messageBytes)
-	if err != nil {
-		return err
-	}
-	m.Content = content
-
-	m.Type = header.Type
-	m.TimeStamp = &header.TimeStamp
-
-	return nil
-}

packet.go

@@ -1,89 +0,0 @@
-package main
-
-const (
-	RemoteGetState            = FrameType(0x01)
-	RemoteHandleMutation      = FrameType(0x02)
-	ResponseBody              = FrameType(0x03)
-	RemoteGetStateReply       = FrameType(0x04)
-	RemoteHandleMutationReply = FrameType(0x05)
-	RemoteCreateOrderReply    = FrameType(0x06)
-)
-
-// type CartPacket struct {
-// 	Version     PackageVersion
-// 	MessageType CartMessage
-// 	DataLength  uint32
-// 	StatusCode  uint32
-// 	Id          CartId
-// }
-
-// type Packet struct {
-// 	Version     PackageVersion
-// 	MessageType PoolMessage
-// 	DataLength  uint32
-// 	StatusCode  uint32
-// }
-
-// var headerData = make([]byte, 4)
-
-// func matchHeader(conn io.Reader) error {
-
-// 	pos := 0
-// 	for pos < 4 {
-
-// 		l, err := conn.Read(headerData)
-// 		if err != nil {
-// 			return err
-// 		}
-// 		for i := 0; i < l; i++ {
-// 			if headerData[i] == header[pos] {
-// 				pos++
-// 				if pos == 4 {
-// 					return nil
-// 				}
-// 			} else {
-// 				pos = 0
-// 			}
-// 		}
-// 	}
-// 	return nil
-// }
-
-// func ReadPacket(conn io.Reader, packet *Packet) error {
-// 	err := matchHeader(conn)
-// 	if err != nil {
-// 		return err
-// 	}
-// 	return binary.Read(conn, binary.LittleEndian, packet)
-// }
-
-// func ReadCartPacket(conn io.Reader, packet *CartPacket) error {
-// 	err := matchHeader(conn)
-// 	if err != nil {
-// 		return err
-// 	}
-// 	return binary.Read(conn, binary.LittleEndian, packet)
-// }
-
-// func GetPacketData(conn io.Reader, len uint32) ([]byte, error) {
-// 	if len == 0 {
-// 		return []byte{}, nil
-// 	}
-// 	data := make([]byte, len)
-// 	_, err := conn.Read(data)
-// 	return data, err
-// }
-
-// func ReceivePacket(conn io.Reader) (uint32, []byte, error) {
-// 	var packet Packet
-// 	err := ReadPacket(conn, &packet)
-// 	if err != nil {
-// 		return 0, nil, err
-// 	}
-
-// 	data, err := GetPacketData(conn, packet.DataLength)
-// 	if err != nil {
-// 		return 0, nil, err
-// 	}
-// 	return packet.MessageType, data, nil
-// }

pkg/actor/disk_storage.go

@@ -0,0 +1,140 @@
+package actor
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"log"
+	"os"
+	"path/filepath"
+	"sync"
+	"time"
+
+	"github.com/gogo/protobuf/proto"
+)
+
+type QueueEvent struct {
+	TimeStamp time.Time
+	Message   proto.Message
+}
+
+type DiskStorage[V any] struct {
+	*StateStorage
+	path  string
+	done  chan struct{}
+	queue *sync.Map // map[uint64][]QueueEvent
+}
+
+type LogStorage[V any] interface {
+	LoadEvents(ctx context.Context, id uint64, grain Grain[V]) error
+	AppendMutations(id uint64, msg ...proto.Message) error
+}
+
+func NewDiskStorage[V any](path string, registry MutationRegistry) *DiskStorage[V] {
+	return &DiskStorage[V]{
+		StateStorage: NewState(registry),
+		path:         path,
+		done:         make(chan struct{}),
+	}
+}
+
+func (s *DiskStorage[V]) SaveLoop(duration time.Duration) {
+	s.queue = &sync.Map{}
+	ticker := time.NewTicker(duration)
+	defer ticker.Stop()
+	for {
+		select {
+		case <-s.done:
+			s.save()
+			return
+		case <-ticker.C:
+			s.save()
+		}
+	}
+}
+
+func (s *DiskStorage[V]) save() {
+	carts := 0
+	lines := 0
+	s.queue.Range(func(key, value any) bool {
+		id := key.(uint64)
+		path := s.logPath(id)
+		fh, err := os.OpenFile(path, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
+		if err != nil {
+			log.Printf("failed to open event log file: %v", err)
+			return true
+		}
+		defer fh.Close()
+
+		if qe, ok := value.([]QueueEvent); ok {
+			for _, msg := range qe {
+				if err := s.Append(fh, msg.Message, msg.TimeStamp); err != nil {
+					log.Printf("failed to append event to log file: %v", err)
+				}
+				lines++
+			}
+		}
+		carts++
+		s.queue.Delete(id)
+		return true
+	})
+	if lines > 0 {
+		log.Printf("Appended %d carts and %d lines to disk", carts, lines)
+	}
+}
+
+func (s *DiskStorage[V]) logPath(id uint64) string {
+	return filepath.Join(s.path, fmt.Sprintf("%d.events.log", id))
+}
+
+func (s *DiskStorage[V]) LoadEvents(ctx context.Context, id uint64, grain Grain[V]) error {
+	path := s.logPath(id)
+	if _, err := os.Stat(path); errors.Is(err, os.ErrNotExist) {
+		// No log -> nothing to replay
+		return nil
+	}
+
+	fh, err := os.Open(path)
+	if err != nil {
+		return fmt.Errorf("open replay file: %w", err)
+	}
+	defer fh.Close()
+	return s.Load(fh, func(msg proto.Message) {
+		s.registry.Apply(ctx, grain, msg)
+	})
+}
+
+func (s *DiskStorage[V]) Close() {
+	if s.queue != nil {
+		s.save()
+	}
+	close(s.done)
+}
+
+func (s *DiskStorage[V]) AppendMutations(id uint64, msg ...proto.Message) error {
+	if s.queue != nil {
+		queue := make([]QueueEvent, 0)
+		data, found := s.queue.Load(id)
+		if found {
+			queue = data.([]QueueEvent)
+		}
+		for _, m := range msg {
+			queue = append(queue, QueueEvent{Message: m, TimeStamp: time.Now()})
+		}
+		s.queue.Store(id, queue)
+		return nil
+	} else {
+		path := s.logPath(id)
+		fh, err := os.OpenFile(path, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
+		if err != nil {
+			log.Printf("failed to open event log file: %v", err)
+			return err
+		}
+		defer fh.Close()
+		for _, m := range msg {
+			err = s.Append(fh, m, time.Now())
+		}
+		return err
+	}
+
+}

pkg/actor/grain.go

@@ -0,0 +1,13 @@
+package actor
+
+import (
+	"time"
+)
+
+type Grain[V any] interface {
+	GetId() uint64
+
+	GetLastAccess() time.Time
+	GetLastChange() time.Time
+	GetCurrentState() (*V, error)
+}

pkg/actor/grain_pool.go

@@ -0,0 +1,44 @@
+package actor
+
+import (
+	"context"
+	"net/http"
+
+	"github.com/gogo/protobuf/proto"
+)
+
+type MutationResult[V any] struct {
+	Result    V             `json:"result"`
+	Mutations []ApplyResult `json:"mutations,omitempty"`
+}
+
+type GrainPool[V any] interface {
+	Apply(ctx context.Context, id uint64, mutation ...proto.Message) (*MutationResult[V], error)
+	Get(ctx context.Context, id uint64) (V, error)
+	OwnerHost(id uint64) (Host, bool)
+	Hostname() string
+	TakeOwnership(id uint64)
+	HandleOwnershipChange(host string, ids []uint64) error
+	HandleRemoteExpiry(host string, ids []uint64) error
+	Negotiate(otherHosts []string)
+	GetLocalIds() []uint64
+	RemoveHost(host string)
+	AddRemoteHost(host string)
+	IsHealthy() bool
+	IsKnown(string) bool
+	GetPubSub() *PubSub
+	Close()
+}
+
+// Host abstracts a remote node capable of proxying cart requests.
+type Host interface {
+	AnnounceExpiry(ids []uint64)
+	Negotiate(otherHosts []string) ([]string, error)
+	Name() string
+	Proxy(id uint64, w http.ResponseWriter, r *http.Request) (bool, error)
+	GetActorIds() []uint64
+	Close() error
+	Ping() bool
+	IsHealthy() bool
+	AnnounceOwnership(ownerHost string, ids []uint64)
+}

pkg/actor/grpc_server.go

@@ -0,0 +1,233 @@
+package actor
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"net"
+	"time"
+
+	messages "git.tornberg.me/go-cart-actor/pkg/messages"
+	"go.opentelemetry.io/contrib/bridges/otelslog"
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/metric"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/reflection"
+)
+
+// ControlServer implements the ControlPlane gRPC services.
+// It delegates to a grain pool and cluster operations to a synced pool.
+type ControlServer[V any] struct {
+	messages.UnimplementedControlPlaneServer
+	pool GrainPool[V]
+}
+
+const name = "grpc_server"
+
+var (
+	tracer                 = otel.Tracer(name)
+	meter                  = otel.Meter(name)
+	logger                 = otelslog.NewLogger(name)
+	pingCalls              metric.Int64Counter
+	negotiateCalls         metric.Int64Counter
+	getLocalActorIdsCalls  metric.Int64Counter
+	announceOwnershipCalls metric.Int64Counter
+	announceExpiryCalls    metric.Int64Counter
+	closingCalls           metric.Int64Counter
+)
+
+func init() {
+	var err error
+	pingCalls, err = meter.Int64Counter("grpc.ping_calls",
+		metric.WithDescription("Number of ping calls"),
+		metric.WithUnit("{calls}"))
+	if err != nil {
+		panic(err)
+	}
+	negotiateCalls, err = meter.Int64Counter("grpc.negotiate_calls",
+		metric.WithDescription("Number of negotiate calls"),
+		metric.WithUnit("{calls}"))
+	if err != nil {
+		panic(err)
+	}
+	getLocalActorIdsCalls, err = meter.Int64Counter("grpc.get_local_actor_ids_calls",
+		metric.WithDescription("Number of get local actor ids calls"),
+		metric.WithUnit("{calls}"))
+	if err != nil {
+		panic(err)
+	}
+	announceOwnershipCalls, err = meter.Int64Counter("grpc.announce_ownership_calls",
+		metric.WithDescription("Number of announce ownership calls"),
+		metric.WithUnit("{calls}"))
+	if err != nil {
+		panic(err)
+	}
+	announceExpiryCalls, err = meter.Int64Counter("grpc.announce_expiry_calls",
+		metric.WithDescription("Number of announce expiry calls"),
+		metric.WithUnit("{calls}"))
+	if err != nil {
+		panic(err)
+	}
+	closingCalls, err = meter.Int64Counter("grpc.closing_calls",
+		metric.WithDescription("Number of closing calls"),
+		metric.WithUnit("{calls}"))
+	if err != nil {
+		panic(err)
+	}
+}
+
+func (s *ControlServer[V]) AnnounceOwnership(ctx context.Context, req *messages.OwnershipAnnounce) (*messages.OwnerChangeAck, error) {
+	ctx, span := tracer.Start(ctx, "grpc_announce_ownership")
+	defer span.End()
+	span.SetAttributes(
+		attribute.String("component", "controlplane"),
+		attribute.String("host", req.Host),
+		attribute.Int("id_count", len(req.Ids)),
+	)
+	logger.InfoContext(ctx, "announce ownership", "host", req.Host, "id_count", len(req.Ids))
+	announceOwnershipCalls.Add(ctx, 1, metric.WithAttributes(attribute.String("host", req.Host)))
+
+	err := s.pool.HandleOwnershipChange(req.Host, req.Ids)
+	if err != nil {
+		span.RecordError(err)
+		return &messages.OwnerChangeAck{
+			Accepted: false,
+			Message:  "owner change failed",
+		}, err
+	}
+
+	log.Printf("Ack count: %d", len(req.Ids))
+	return &messages.OwnerChangeAck{
+		Accepted: true,
+		Message:  "ownership announced",
+	}, nil
+}
+
+func (s *ControlServer[V]) AnnounceExpiry(ctx context.Context, req *messages.ExpiryAnnounce) (*messages.OwnerChangeAck, error) {
+	ctx, span := tracer.Start(ctx, "grpc_announce_expiry")
+	defer span.End()
+	span.SetAttributes(
+		attribute.String("component", "controlplane"),
+		attribute.String("host", req.Host),
+		attribute.Int("id_count", len(req.Ids)),
+	)
+	logger.InfoContext(ctx, "announce expiry", "host", req.Host, "id_count", len(req.Ids))
+	announceExpiryCalls.Add(ctx, 1, metric.WithAttributes(attribute.String("host", req.Host)))
+
+	err := s.pool.HandleRemoteExpiry(req.Host, req.Ids)
+	if err != nil {
+		span.RecordError(err)
+	}
+	return &messages.OwnerChangeAck{
+		Accepted: err == nil,
+		Message:  "expiry acknowledged",
+	}, nil
+}
+
+// ControlPlane: Ping
+func (s *ControlServer[V]) Ping(ctx context.Context, _ *messages.Empty) (*messages.PingReply, error) {
+
+	host := s.pool.Hostname()
+
+	pingCalls.Add(ctx, 1, metric.WithAttributes(attribute.String("host", host)))
+
+	// log.Printf("got ping")
+	return &messages.PingReply{
+		Host:     host,
+		UnixTime: time.Now().Unix(),
+	}, nil
+}
+
+// ControlPlane: Negotiate (merge host views)
+func (s *ControlServer[V]) Negotiate(ctx context.Context, req *messages.NegotiateRequest) (*messages.NegotiateReply, error) {
+	ctx, span := tracer.Start(ctx, "grpc_negotiate")
+	defer span.End()
+	span.SetAttributes(
+		attribute.String("component", "controlplane"),
+		attribute.Int("known_hosts_count", len(req.KnownHosts)),
+	)
+	logger.InfoContext(ctx, "negotiate", "known_hosts_count", len(req.KnownHosts))
+	negotiateCalls.Add(ctx, 1)
+
+	s.pool.Negotiate(req.KnownHosts)
+	return &messages.NegotiateReply{Hosts: req.GetKnownHosts()}, nil
+}
+
+// ControlPlane: GetCartIds (locally owned carts only)
+func (s *ControlServer[V]) GetLocalActorIds(ctx context.Context, _ *messages.Empty) (*messages.ActorIdsReply, error) {
+	ctx, span := tracer.Start(ctx, "grpc_get_local_actor_ids")
+	defer span.End()
+	ids := s.pool.GetLocalIds()
+	span.SetAttributes(
+		attribute.String("component", "controlplane"),
+		attribute.Int("id_count", len(ids)),
+	)
+	logger.InfoContext(ctx, "get local actor ids", "id_count", len(ids))
+	getLocalActorIdsCalls.Add(ctx, 1)
+
+	return &messages.ActorIdsReply{Ids: ids}, nil
+}
+
+// ControlPlane: Closing (peer shutdown notification)
+func (s *ControlServer[V]) Closing(ctx context.Context, req *messages.ClosingNotice) (*messages.OwnerChangeAck, error) {
+	ctx, span := tracer.Start(ctx, "grpc_closing")
+	defer span.End()
+	host := req.GetHost()
+	span.SetAttributes(
+		attribute.String("component", "controlplane"),
+		attribute.String("host", host),
+	)
+	logger.InfoContext(ctx, "closing notice", "host", host)
+	closingCalls.Add(ctx, 1, metric.WithAttributes(attribute.String("host", host)))
+
+	if host != "" {
+		s.pool.RemoveHost(host)
+	}
+	return &messages.OwnerChangeAck{
+		Accepted: true,
+		Message:  "removed host",
+	}, nil
+}
+
+type ServerConfig struct {
+	Addr    string
+	Options []grpc.ServerOption
+}
+
+func NewServerConfig(addr string, options ...grpc.ServerOption) ServerConfig {
+	return ServerConfig{
+		Addr:    addr,
+		Options: options,
+	}
+}
+
+func DefaultServerConfig() ServerConfig {
+	return NewServerConfig(":1337")
+}
+
+// StartGRPCServer configures and starts the unified gRPC server on the given address.
+// It registers both the CartActor and ControlPlane services.
+func NewControlServer[V any](config ServerConfig, pool GrainPool[V]) (*grpc.Server, error) {
+	lis, err := net.Listen("tcp", config.Addr)
+	if err != nil {
+		return nil, fmt.Errorf("failed to listen: %w", err)
+	}
+
+	grpcServer := grpc.NewServer(config.Options...)
+	server := &ControlServer[V]{
+		pool: pool,
+	}
+
+	messages.RegisterControlPlaneServer(grpcServer, server)
+	reflection.Register(grpcServer)
+
+	log.Printf("gRPC server listening as %s on %s", pool.Hostname(), config.Addr)
+	go func() {
+		if err := grpcServer.Serve(lis); err != nil {
+			log.Fatalf("failed to serve gRPC: %v", err)
+		}
+	}()
+
+	return grpcServer, nil
+}

pkg/actor/log_listerner.go

@@ -0,0 +1,47 @@
+package actor
+
+import (
+	"log"
+
+	"github.com/matst80/slask-finder/pkg/messaging"
+	amqp "github.com/rabbitmq/amqp091-go"
+)
+
+type LogListener interface {
+	AppendMutations(id uint64, msg ...ApplyResult)
+}
+
+type AmqpListener struct {
+	conn        *amqp.Connection
+	transformer func(id uint64, msg []ApplyResult) (any, error)
+}
+
+func NewAmqpListener(conn *amqp.Connection, transformer func(id uint64, msg []ApplyResult) (any, error)) *AmqpListener {
+	return &AmqpListener{
+		conn:        conn,
+		transformer: transformer,
+	}
+}
+
+func (l *AmqpListener) DefineTopics() {
+	ch, err := l.conn.Channel()
+	if err != nil {
+		log.Fatalf("Failed to open a channel: %v", err)
+	}
+	defer ch.Close()
+	if err := messaging.DefineTopic(ch, "cart", "mutation"); err != nil {
+		log.Fatalf("Failed to declare topic mutation: %v", err)
+	}
+}
+
+func (l *AmqpListener) AppendMutations(id uint64, msg ...ApplyResult) {
+	data, err := l.transformer(id, msg)
+	if err != nil {
+		log.Printf("Failed to transform mutation event: %v", err)
+		return
+	}
+	err = messaging.SendChange(l.conn, "cart", "mutation", data)
+	if err != nil {
+		log.Printf("Failed to send mutation event: %v", err)
+	}
+}

pkg/actor/mutation_registry.go

@@ -0,0 +1,285 @@
+package actor
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"reflect"
+	"sync"
+
+	"github.com/gogo/protobuf/proto"
+	"go.opentelemetry.io/otel/attribute"
+)
+
+type ApplyResult struct {
+	Type     string        `json:"type"`
+	Mutation proto.Message `json:"mutation"`
+	Error    error         `json:"error,omitempty"`
+}
+
+type MutationProcessor interface {
+	Process(ctx context.Context, grain any) error
+}
+
+type BasicMutationProcessor[V any] struct {
+	processor func(ctx context.Context, grain V) error
+}
+
+func NewMutationProcessor[V any](process func(ctx context.Context, grain V) error) MutationProcessor {
+	return &BasicMutationProcessor[V]{
+		processor: process,
+	}
+}
+
+func (p *BasicMutationProcessor[V]) Process(ctx context.Context, grain any) error {
+	return p.processor(ctx, grain.(V))
+}
+
+type MutationRegistry interface {
+	Apply(ctx context.Context, grain any, msg ...proto.Message) ([]ApplyResult, error)
+	RegisterMutations(handlers ...MutationHandler)
+	Create(typeName string) (proto.Message, bool)
+	GetTypeName(msg proto.Message) (string, bool)
+	RegisterProcessor(processor ...MutationProcessor)
+	//GetStorageEvent(msg proto.Message) StorageEvent
+	//FromStorageEvent(event StorageEvent) (proto.Message, error)
+}
+
+type ProtoMutationRegistry struct {
+	mutationRegistryMu sync.RWMutex
+	mutationRegistry   map[reflect.Type]MutationHandler
+	processors         []MutationProcessor
+}
+
+var (
+	ErrMutationNotRegistered = &MutationError{
+		Message:    "mutation not registered",
+		Code:       255,
+		StatusCode: 500,
+	}
+)
+
+type MutationError struct {
+	Message    string `json:"message"`
+	Code       uint32 `json:"code"`
+	StatusCode uint32 `json:"status_code"`
+}
+
+func (m MutationError) Error() string {
+	return m.Message
+}
+
+// MutationOption configures additional behavior for a registered mutation.
+type MutationOption func(*mutationOptions)
+
+// mutationOptions holds flags adjustable per registration.
+type mutationOptions struct {
+	updateTotals bool
+}
+
+// WithTotals ensures CartGrain.UpdateTotals() is called after a successful handler.
+func WithTotals() MutationOption {
+	return func(o *mutationOptions) {
+		o.updateTotals = true
+	}
+}
+
+type MutationHandler interface {
+	Handle(state any, msg proto.Message) error
+	Name() string
+	Type() reflect.Type
+	Create() proto.Message
+}
+
+// RegisteredMutation stores metadata + the execution closure.
+type RegisteredMutation[V any, T proto.Message] struct {
+	name    string
+	handler func(*V, T) error
+	create  func() T
+	msgType reflect.Type
+}
+
+func NewMutation[V any, T proto.Message](handler func(*V, T) error, create func() T) *RegisteredMutation[V, T] {
+	// Derive the name and message type from a concrete instance produced by create().
+	// This avoids relying on reflect.TypeFor (which can yield unexpected results in some toolchains)
+	// and ensures we always peel off the pointer layer for proto messages.
+	instance := create()
+	rt := reflect.TypeOf(instance)
+	if rt.Kind() == reflect.Ptr {
+		rt = rt.Elem()
+	}
+	return &RegisteredMutation[V, T]{
+		name:    rt.Name(),
+		handler: handler,
+		create:  create,
+		msgType: rt,
+	}
+}
+
+func (m *RegisteredMutation[V, T]) Handle(state any, msg proto.Message) error {
+	return m.handler(state.(*V), msg.(T))
+}
+
+func (m *RegisteredMutation[V, T]) Name() string {
+	return m.name
+}
+
+func (m *RegisteredMutation[V, T]) Create() proto.Message {
+	return m.create()
+}
+
+func (m *RegisteredMutation[V, T]) Type() reflect.Type {
+	return m.msgType
+}
+
+func NewMutationRegistry() MutationRegistry {
+	return &ProtoMutationRegistry{
+		mutationRegistry:   make(map[reflect.Type]MutationHandler),
+		mutationRegistryMu: sync.RWMutex{},
+		processors:         make([]MutationProcessor, 0),
+	}
+}
+
+func (r *ProtoMutationRegistry) RegisterProcessor(processors ...MutationProcessor) {
+	r.processors = append(r.processors, processors...)
+}
+
+func (r *ProtoMutationRegistry) RegisterMutations(handlers ...MutationHandler) {
+	r.mutationRegistryMu.Lock()
+	defer r.mutationRegistryMu.Unlock()
+
+	for _, handler := range handlers {
+		r.mutationRegistry[handler.Type()] = handler
+	}
+}
+
+func (r *ProtoMutationRegistry) GetTypeName(msg proto.Message) (string, bool) {
+	r.mutationRegistryMu.RLock()
+	defer r.mutationRegistryMu.RUnlock()
+
+	rt := indirectType(reflect.TypeOf(msg))
+	if handler, ok := r.mutationRegistry[rt]; ok {
+		return handler.Name(), true
+	}
+	return "", false
+}
+
+func (r *ProtoMutationRegistry) getHandler(typeName string) MutationHandler {
+	r.mutationRegistryMu.Lock()
+	defer r.mutationRegistryMu.Unlock()
+
+	for _, handler := range r.mutationRegistry {
+		if handler.Name() == typeName {
+			return handler
+		}
+	}
+
+	return nil
+}
+
+func (r *ProtoMutationRegistry) Create(typeName string) (proto.Message, bool) {
+
+	handler := r.getHandler(typeName)
+	if handler == nil {
+		log.Printf("missing handler for %s", typeName)
+		return nil, false
+	}
+
+	return handler.Create(), true
+}
+
+// ApplyRegistered attempts to apply a registered mutation.
+// Returns updated grain if successful.
+//
+// If the mutation is not registered, returns (nil, ErrMutationNotRegistered).
+func (r *ProtoMutationRegistry) Apply(ctx context.Context, grain any, msg ...proto.Message) ([]ApplyResult, error) {
+
+	parentCtx, span := tracer.Start(ctx, "apply mutations")
+	defer span.End()
+	span.SetAttributes(
+		attribute.String("component", "registry"),
+		attribute.Int("mutations", len(msg)),
+	)
+
+	results := make([]ApplyResult, 0, len(msg))
+
+	if grain == nil {
+		return results, fmt.Errorf("nil grain")
+	}
+	// Nil slice of mutations still treated as an error (call contract violation).
+	if msg == nil {
+		return results, fmt.Errorf("nil mutation message")
+	}
+
+	for _, m := range msg {
+		// Ignore nil mutation elements (untyped or typed nil pointers) silently; they carry no data.
+		if m == nil {
+			continue
+		}
+		// Typed nil: interface holds concrete proto message type whose pointer value is nil.
+		rv := reflect.ValueOf(m)
+		if rv.Kind() == reflect.Ptr && rv.IsNil() {
+			continue
+		}
+		rt := indirectType(reflect.TypeOf(m))
+		_, msgSpan := tracer.Start(parentCtx, rt.Name())
+
+		r.mutationRegistryMu.RLock()
+		entry, ok := r.mutationRegistry[rt]
+		r.mutationRegistryMu.RUnlock()
+		if !ok {
+			results = append(results, ApplyResult{Error: ErrMutationNotRegistered, Type: rt.Name(), Mutation: m})
+			continue
+		} else {
+			err := entry.Handle(grain, m)
+			if err != nil {
+				msgSpan.RecordError(err)
+			}
+			results = append(results, ApplyResult{Error: err, Type: rt.Name(), Mutation: m})
+		}
+		msgSpan.End()
+	}
+
+	if len(results) > 0 {
+		processCtx, processSpan := tracer.Start(ctx, "after mutation processors")
+		defer processSpan.End()
+		for _, processor := range r.processors {
+
+			err := processor.Process(processCtx, grain)
+			if err != nil {
+				return results, err
+			}
+		}
+	}
+	return results, nil
+}
+
+// RegisteredMutations returns metadata for all registered mutations (snapshot).
+func (r *ProtoMutationRegistry) RegisteredMutations() []string {
+	r.mutationRegistryMu.RLock()
+	defer r.mutationRegistryMu.RUnlock()
+	out := make([]string, 0, len(r.mutationRegistry))
+	for _, entry := range r.mutationRegistry {
+		out = append(out, entry.Name())
+	}
+	return out
+}
+
+// RegisteredMutationTypes returns the reflect.Type list of all registered messages.
+// Useful for coverage tests ensuring expected set matches actual set.
+func (r *ProtoMutationRegistry) RegisteredMutationTypes() []reflect.Type {
+	r.mutationRegistryMu.RLock()
+	defer r.mutationRegistryMu.RUnlock()
+	out := make([]reflect.Type, 0, len(r.mutationRegistry))
+	for _, entry := range r.mutationRegistry {
+		out = append(out, entry.Type())
+	}
+	return out
+}
+
+func indirectType(t reflect.Type) reflect.Type {
+	for t.Kind() == reflect.Ptr {
+		t = t.Elem()
+	}
+	return t
+}

pkg/actor/mutation_registry_test.go

@@ -0,0 +1,135 @@
+package actor
+
+import (
+	"context"
+	"errors"
+	"reflect"
+	"slices"
+	"testing"
+
+	"git.tornberg.me/go-cart-actor/pkg/messages"
+)
+
+type cartState struct {
+	calls     int
+	lastAdded *messages.AddItem
+}
+
+func TestRegisteredMutationBasics(t *testing.T) {
+	reg := NewMutationRegistry().(*ProtoMutationRegistry)
+
+	addItemMutation := NewMutation(
+		func(state *cartState, msg *messages.AddItem) error {
+			state.calls++
+			// copy to avoid external mutation side-effects (not strictly necessary for the test)
+			cp := msg
+			state.lastAdded = cp
+			return nil
+		},
+		func() *messages.AddItem { return &messages.AddItem{} },
+	)
+
+	// Sanity check on mutation metadata
+	if addItemMutation.Name() != "AddItem" {
+		t.Fatalf("expected mutation Name() == AddItem, got %s", addItemMutation.Name())
+	}
+	if got, want := addItemMutation.Type(), reflect.TypeOf(messages.AddItem{}); got != want {
+		t.Fatalf("expected Type() == %v, got %v", want, got)
+	}
+
+	reg.RegisterMutations(addItemMutation)
+
+	// RegisteredMutations: membership (order not guaranteed)
+	names := reg.RegisteredMutations()
+	if !slices.Contains(names, "AddItem") {
+		t.Fatalf("RegisteredMutations missing AddItem, got %v", names)
+	}
+
+	// RegisteredMutationTypes: membership (order not guaranteed)
+	types := reg.RegisteredMutationTypes()
+	if !slices.Contains(types, reflect.TypeOf(messages.AddItem{})) {
+		t.Fatalf("RegisteredMutationTypes missing AddItem type, got %v", types)
+	}
+
+	// GetTypeName should resolve for a pointer instance
+	name, ok := reg.GetTypeName(&messages.AddItem{})
+	if !ok || name != "AddItem" {
+		t.Fatalf("GetTypeName returned (%q,%v), expected (AddItem,true)", name, ok)
+	}
+
+	// GetTypeName should fail for unregistered type
+	if name, ok := reg.GetTypeName(&messages.Noop{}); ok || name != "" {
+		t.Fatalf("expected GetTypeName to fail for unregistered message, got (%q,%v)", name, ok)
+	}
+
+	// Create by name
+	msg, ok := reg.Create("AddItem")
+	if !ok {
+		t.Fatalf("Create failed for registered mutation")
+	}
+	if _, isAddItem := msg.(*messages.AddItem); !isAddItem {
+		t.Fatalf("Create returned wrong concrete type: %T", msg)
+	}
+
+	// Create unknown
+	if m2, ok := reg.Create("Unknown"); ok || m2 != nil {
+		t.Fatalf("Create should fail for unknown mutation, got (%T,%v)", m2, ok)
+	}
+
+	// Apply happy path
+	state := &cartState{}
+	add := &messages.AddItem{ItemId: 42, Quantity: 3, Sku: "ABC"}
+	if _, err := reg.Apply(context.Background(), state, add); err != nil {
+		t.Fatalf("Apply returned error: %v", err)
+	}
+	if state.calls != 1 {
+		t.Fatalf("handler not invoked expected calls=1 got=%d", state.calls)
+	}
+	if state.lastAdded == nil || state.lastAdded.ItemId != 42 || state.lastAdded.Quantity != 3 {
+		t.Fatalf("state not updated correctly: %+v", state.lastAdded)
+	}
+
+	// Apply nil grain
+	if _, err := reg.Apply(nil, add); err == nil {
+		t.Fatalf("expected error for nil grain")
+	}
+
+	// Apply nil message
+	if _, err := reg.Apply(context.Background(), state, nil); err == nil {
+		t.Fatalf("expected error for nil mutation message")
+	}
+
+	// Apply unregistered message
+	if _, err := reg.Apply(context.Background(), state, &messages.Noop{}); !errors.Is(err, ErrMutationNotRegistered) {
+		t.Fatalf("expected ErrMutationNotRegistered, got %v", err)
+	}
+}
+
+// func TestConcurrentSafeRegistrationLookup(t *testing.T) {
+// 	// This test is light-weight; it ensures locks don't deadlock under simple concurrent access.
+// 	reg := NewMutationRegistry().(*ProtoMutationRegistry)
+// 	mut := NewMutation[cartState, *messages.Noop](
+// 		func(state *cartState, msg *messages.Noop) error { state.calls++; return nil },
+// 		func() *messages.Noop { return &messages.Noop{} },
+// 	)
+// 	reg.RegisterMutations(mut)
+
+// 	done := make(chan struct{})
+// 	const workers = 25
+// 	for i := 0; i < workers; i++ {
+// 		go func() {
+// 			for j := 0; j < 100; j++ {
+// 				_, _ = reg.Create("Noop")
+// 				_, _ = reg.GetTypeName(&messages.Noop{})
+// 				_ = reg.Apply(&cartState{}, &messages.Noop{})
+// 			}
+// 			done <- struct{}{}
+// 		}()
+// 	}
+
+// 	for i := 0; i < workers; i++ {
+// 		<-done
+// 	}
+// }
+
+// Helpers

pkg/actor/pubsub.go

@@ -0,0 +1,93 @@
+package actor
+
+import (
+	"sync"
+)
+
+// Event represents an event to be published.
+type Event struct {
+	Topic   string
+	Payload interface{}
+}
+
+// NotifyFunc is a function to notify a grain of an event.
+type NotifyFunc func(grainID uint64, event Event)
+
+// Subscribable is an interface for grains that can receive notifications.
+type Subscribable interface {
+	Notify(event Event)
+	UpdateSubscriptions(pubsub *PubSub)
+}
+
+// PubSub manages subscriptions for grains to topics.
+// Topics are strings, e.g., "sku:12345"
+// Subscribers are grain IDs (uint64)
+type PubSub struct {
+	subscribers map[string][]uint64
+	mu          sync.RWMutex
+	notify      NotifyFunc
+}
+
+// NewPubSub creates a new PubSub instance.
+func NewPubSub(notify NotifyFunc) *PubSub {
+	return &PubSub{
+		subscribers: make(map[string][]uint64),
+		notify:      notify,
+	}
+}
+
+// Subscribe adds a grain ID to the subscribers of a topic.
+func (p *PubSub) Subscribe(topic string, grainID uint64) {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	p.subscribers[topic] = append(p.subscribers[topic], grainID)
+}
+
+// Unsubscribe removes a grain ID from the subscribers of a topic.
+func (p *PubSub) Unsubscribe(topic string, grainID uint64) {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	list := p.subscribers[topic]
+	for i, id := range list {
+		if id == grainID {
+			p.subscribers[topic] = append(list[:i], list[i+1:]...)
+			break
+		}
+	}
+	// If list is empty, could delete, but not necessary
+}
+
+// UnsubscribeAll removes the grain ID from all topics.
+func (p *PubSub) UnsubscribeAll(grainID uint64) {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	for topic, list := range p.subscribers {
+		newList := make([]uint64, 0, len(list))
+		for _, id := range list {
+			if id != grainID {
+				newList = append(newList, id)
+			}
+		}
+		if len(newList) == 0 {
+			delete(p.subscribers, topic)
+		} else {
+			p.subscribers[topic] = newList
+		}
+	}
+}
+
+// GetSubscribers returns a copy of the subscriber IDs for a topic.
+func (p *PubSub) GetSubscribers(topic string) []uint64 {
+	p.mu.RLock()
+	defer p.mu.RUnlock()
+	list := p.subscribers[topic]
+	return append([]uint64(nil), list...)
+}
+
+// Publish sends an event to all subscribers of the topic.
+func (p *PubSub) Publish(event Event) {
+	subs := p.GetSubscribers(event.Topic)
+	for _, id := range subs {
+		p.notify(id, event)
+	}
+}

pkg/actor/simple_grain_pool.go

@@ -0,0 +1,478 @@
+package actor
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"maps"
+	"sync"
+	"time"
+
+	"github.com/gogo/protobuf/proto"
+)
+
+type SimpleGrainPool[V any] struct {
+	// fields and methods
+	localMu          sync.RWMutex
+	grains           map[uint64]Grain[V]
+	mutationRegistry MutationRegistry
+	spawn            func(ctx context.Context, id uint64) (Grain[V], error)
+	spawnHost        func(host string) (Host, error)
+	listeners        []LogListener
+	storage          LogStorage[V]
+	ttl              time.Duration
+	poolSize         int
+	pubsub           *PubSub
+
+	// Cluster coordination --------------------------------------------------
+	hostname     string
+	remoteMu     sync.RWMutex
+	remoteOwners map[uint64]Host
+	remoteHosts  map[string]Host
+	//discardedHostHandler *DiscardedHostHandler
+
+	// House-keeping ---------------------------------------------------------
+	purgeTicker *time.Ticker
+}
+
+type GrainPoolConfig[V any] struct {
+	Hostname         string
+	Spawn            func(ctx context.Context, id uint64) (Grain[V], error)
+	SpawnHost        func(host string) (Host, error)
+	TTL              time.Duration
+	PoolSize         int
+	MutationRegistry MutationRegistry
+	Storage          LogStorage[V]
+}
+
+func NewSimpleGrainPool[V any](config GrainPoolConfig[V]) (*SimpleGrainPool[V], error) {
+	p := &SimpleGrainPool[V]{
+		grains:           make(map[uint64]Grain[V]),
+		mutationRegistry: config.MutationRegistry,
+		storage:          config.Storage,
+		spawn:            config.Spawn,
+		spawnHost:        config.SpawnHost,
+		ttl:              config.TTL,
+		poolSize:         config.PoolSize,
+		hostname:         config.Hostname,
+		remoteOwners:     make(map[uint64]Host),
+		remoteHosts:      make(map[string]Host),
+	}
+
+	p.purgeTicker = time.NewTicker(time.Minute)
+	go func() {
+		for range p.purgeTicker.C {
+			p.purge()
+		}
+	}()
+
+	return p, nil
+}
+
+func (p *SimpleGrainPool[V]) AddListener(listener LogListener) {
+	p.listeners = append(p.listeners, listener)
+}
+
+func (p *SimpleGrainPool[V]) RemoveListener(listener LogListener) {
+	for i, l := range p.listeners {
+		if l == listener {
+			p.listeners = append(p.listeners[:i], p.listeners[i+1:]...)
+			break
+		}
+	}
+}
+
+func (p *SimpleGrainPool[V]) purge() {
+	purgeLimit := time.Now().Add(-p.ttl)
+	purgedIds := make([]uint64, 0, len(p.grains))
+	p.localMu.Lock()
+	for id, grain := range p.grains {
+		if grain.GetLastAccess().Before(purgeLimit) {
+			purgedIds = append(purgedIds, id)
+			if p.pubsub != nil {
+				p.pubsub.UnsubscribeAll(id)
+			}
+			delete(p.grains, id)
+		}
+	}
+	p.localMu.Unlock()
+	p.forAllHosts(func(remote Host) {
+		remote.AnnounceExpiry(purgedIds)
+	})
+
+}
+
+// LocalUsage returns the number of resident grains and configured capacity.
+func (p *SimpleGrainPool[V]) LocalUsage() (int, int) {
+	p.localMu.RLock()
+	defer p.localMu.RUnlock()
+	return len(p.grains), p.poolSize
+}
+
+// LocalCartIDs returns the currently owned cart ids (for control-plane RPCs).
+func (p *SimpleGrainPool[V]) GetLocalIds() []uint64 {
+	p.localMu.RLock()
+	defer p.localMu.RUnlock()
+	ids := make([]uint64, 0, len(p.grains))
+	for _, g := range p.grains {
+		if g == nil {
+			continue
+		}
+		ids = append(ids, uint64(g.GetId()))
+	}
+	return ids
+}
+
+func (p *SimpleGrainPool[V]) HandleRemoteExpiry(host string, ids []uint64) error {
+	p.remoteMu.Lock()
+	defer p.remoteMu.Unlock()
+	for _, id := range ids {
+		delete(p.remoteOwners, id)
+	}
+	return nil
+}
+
+func (p *SimpleGrainPool[V]) HandleOwnershipChange(host string, ids []uint64) error {
+	log.Printf("host %s now owns %d cart ids", host, len(ids))
+	p.remoteMu.RLock()
+	remoteHost, exists := p.remoteHosts[host]
+	p.remoteMu.RUnlock()
+	if !exists {
+		createdHost, err := p.AddRemote(host)
+		if err != nil {
+			return err
+		}
+		remoteHost = createdHost
+	}
+	p.remoteMu.Lock()
+	defer p.remoteMu.Unlock()
+	p.localMu.Lock()
+	defer p.localMu.Unlock()
+	for _, id := range ids {
+		log.Printf("Handling ownership change for cart %d to host %s", id, host)
+		delete(p.grains, id)
+		p.remoteOwners[id] = remoteHost
+	}
+	return nil
+}
+
+// TakeOwnership takes ownership of a grain.
+func (p *SimpleGrainPool[V]) TakeOwnership(id uint64) {
+	p.broadcastOwnership([]uint64{id})
+}
+
+func (p *SimpleGrainPool[V]) AddRemoteHost(host string) {
+	p.AddRemote(host)
+}
+
+func (p *SimpleGrainPool[V]) AddRemote(host string) (Host, error) {
+	if host == "" {
+		return nil, fmt.Errorf("host is empty")
+	}
+	if host == p.hostname {
+		return nil, fmt.Errorf("same host, this should not happen")
+	}
+	p.remoteMu.RLock()
+	existing, found := p.remoteHosts[host]
+	p.remoteMu.RUnlock()
+	if found {
+		return existing, nil
+	}
+
+	remote, err := p.spawnHost(host)
+	if err != nil {
+		log.Printf("AddRemote %s failed: %v", host, err)
+
+		return nil, err
+	}
+	p.remoteMu.Lock()
+	p.remoteHosts[host] = remote
+	p.remoteMu.Unlock()
+	// connectedRemotes.Set(float64(p.RemoteCount()))
+
+	log.Printf("Connected to remote host %s", host)
+	go p.pingLoop(remote)
+	go p.initializeRemote(remote)
+	go p.SendNegotiation()
+	return remote, nil
+}
+
+func (p *SimpleGrainPool[V]) initializeRemote(remote Host) {
+
+	remotesIds := remote.GetActorIds()
+
+	p.remoteMu.Lock()
+	for _, id := range remotesIds {
+		p.localMu.Lock()
+		delete(p.grains, id)
+		p.localMu.Unlock()
+		if _, exists := p.remoteOwners[id]; !exists {
+			p.remoteOwners[id] = remote
+		}
+	}
+	p.remoteMu.Unlock()
+
+}
+
+func (p *SimpleGrainPool[V]) RemoveHost(host string) {
+	p.remoteMu.Lock()
+	remote, exists := p.remoteHosts[host]
+
+	if exists {
+		go remote.Close()
+		delete(p.remoteHosts, host)
+	}
+	count := 0
+	for id, owner := range p.remoteOwners {
+		if owner.Name() == host {
+			count++
+			delete(p.remoteOwners, id)
+		}
+	}
+	log.Printf("Removing host %s, grains: %d", host, count)
+	p.remoteMu.Unlock()
+
+	if exists {
+		remote.Close()
+	}
+	// connectedRemotes.Set(float64(p.RemoteCount()))
+}
+
+func (p *SimpleGrainPool[V]) RemoteCount() int {
+	p.remoteMu.RLock()
+	defer p.remoteMu.RUnlock()
+	return len(p.remoteHosts)
+}
+
+// RemoteHostNames returns a snapshot of connected remote host identifiers.
+func (p *SimpleGrainPool[V]) RemoteHostNames() []string {
+	p.remoteMu.RLock()
+	defer p.remoteMu.RUnlock()
+	hosts := make([]string, 0, len(p.remoteHosts))
+	for host := range p.remoteHosts {
+		hosts = append(hosts, host)
+	}
+	return hosts
+}
+
+func (p *SimpleGrainPool[V]) IsKnown(host string) bool {
+	if host == p.hostname {
+		return true
+	}
+	p.remoteMu.RLock()
+	defer p.remoteMu.RUnlock()
+	_, ok := p.remoteHosts[host]
+	return ok
+}
+
+func (p *SimpleGrainPool[V]) pingLoop(remote Host) {
+	remote.Ping()
+	ticker := time.NewTicker(5 * time.Second)
+	defer ticker.Stop()
+	for range ticker.C {
+		if !remote.Ping() {
+			if !remote.IsHealthy() {
+				log.Printf("Remote %s unhealthy, removing", remote.Name())
+				p.Close()
+				p.RemoveHost(remote.Name())
+				return
+			}
+			continue
+		}
+	}
+}
+
+func (p *SimpleGrainPool[V]) IsHealthy() bool {
+	p.remoteMu.RLock()
+	defer p.remoteMu.RUnlock()
+	for _, r := range p.remoteHosts {
+		if !r.IsHealthy() {
+			return false
+		}
+	}
+	return true
+}
+
+func (p *SimpleGrainPool[V]) Negotiate(otherHosts []string) {
+
+	for _, host := range otherHosts {
+		if host != p.hostname {
+			p.remoteMu.RLock()
+			_, ok := p.remoteHosts[host]
+			p.remoteMu.RUnlock()
+			if !ok {
+				go p.AddRemote(host)
+			}
+		}
+	}
+}
+
+func (p *SimpleGrainPool[V]) SendNegotiation() {
+	//negotiationCount.Inc()
+
+	p.remoteMu.RLock()
+	hosts := make([]string, 0, len(p.remoteHosts)+1)
+	hosts = append(hosts, p.hostname)
+	remotes := make([]Host, 0, len(p.remoteHosts))
+	for h, r := range p.remoteHosts {
+		hosts = append(hosts, h)
+		remotes = append(remotes, r)
+	}
+	p.remoteMu.RUnlock()
+
+	p.forAllHosts(func(remote Host) {
+		knownByRemote, err := remote.Negotiate(hosts)
+
+		if err != nil {
+			log.Printf("Negotiate with %s failed: %v", remote.Name(), err)
+			return
+		}
+		for _, h := range knownByRemote {
+			if !p.IsKnown(h) {
+				go p.AddRemote(h)
+			}
+		}
+	})
+}
+
+func (p *SimpleGrainPool[V]) forAllHosts(fn func(Host)) {
+	p.remoteMu.RLock()
+	rh := maps.Clone(p.remoteHosts)
+	p.remoteMu.RUnlock()
+
+	wg := sync.WaitGroup{}
+	for _, host := range rh {
+
+		wg.Go(func() { fn(host) })
+
+	}
+
+	for name, host := range rh {
+		if !host.IsHealthy() {
+			host.Close()
+			p.remoteMu.Lock()
+			delete(p.remoteHosts, name)
+			p.remoteMu.Unlock()
+		}
+
+	}
+}
+
+func (p *SimpleGrainPool[V]) broadcastOwnership(ids []uint64) {
+	if len(ids) == 0 {
+		return
+	}
+
+	p.forAllHosts(func(rh Host) {
+		rh.AnnounceOwnership(p.hostname, ids)
+	})
+	log.Printf("%s taking ownership of %d ids", p.hostname, len(ids))
+	// go p.statsUpdate()
+}
+
+func (p *SimpleGrainPool[V]) getOrClaimGrain(ctx context.Context, id uint64) (Grain[V], error) {
+	p.localMu.RLock()
+	grain, exists := p.grains[id]
+	p.localMu.RUnlock()
+	if exists && grain != nil {
+		return grain, nil
+	}
+
+	grain, err := p.spawn(ctx, id)
+	if err != nil {
+		return nil, err
+	}
+	p.localMu.Lock()
+	p.grains[id] = grain
+	p.localMu.Unlock()
+	go p.broadcastOwnership([]uint64{id})
+	return grain, nil
+}
+
+// // ErrNotOwner is returned when a cart belongs to another host.
+// var ErrNotOwner = fmt.Errorf("not owner")
+
+// Apply applies a mutation to a grain.
+func (p *SimpleGrainPool[V]) Apply(ctx context.Context, id uint64, mutation ...proto.Message) (*MutationResult[*V], error) {
+	grain, err := p.getOrClaimGrain(ctx, id)
+	if err != nil {
+		return nil, err
+	}
+
+	mutations, err := p.mutationRegistry.Apply(ctx, grain, mutation...)
+	if err != nil {
+		return nil, err
+	}
+	if p.storage != nil {
+		go func() {
+			if err := p.storage.AppendMutations(id, mutation...); err != nil {
+				log.Printf("failed to store mutation for grain %d: %v", id, err)
+			}
+		}()
+	}
+	for _, listener := range p.listeners {
+		go listener.AppendMutations(id, mutations...)
+	}
+	result, err := grain.GetCurrentState()
+	if err != nil {
+		return nil, err
+	}
+	if p.pubsub != nil {
+		if sub, ok := any(grain).(Subscribable); ok {
+			sub.UpdateSubscriptions(p.pubsub)
+		}
+	}
+	return &MutationResult[*V]{
+		Result:    result,
+		Mutations: mutations,
+	}, nil
+}
+
+// Get returns the current state of a grain.
+func (p *SimpleGrainPool[V]) Get(ctx context.Context, id uint64) (*V, error) {
+	grain, err := p.getOrClaimGrain(ctx, id)
+	if err != nil {
+		return nil, err
+	}
+	return grain.GetCurrentState()
+}
+
+// OwnerHost reports the remote owner (if any) for the supplied cart id.
+func (p *SimpleGrainPool[V]) OwnerHost(id uint64) (Host, bool) {
+	p.remoteMu.RLock()
+	defer p.remoteMu.RUnlock()
+	owner, ok := p.remoteOwners[id]
+	return owner, ok
+}
+
+// Hostname returns the local hostname (pod IP).
+func (p *SimpleGrainPool[V]) Hostname() string {
+	return p.hostname
+}
+
+// GetPubSub returns the pubsub instance.
+func (p *SimpleGrainPool[V]) GetPubSub() *PubSub {
+	return p.pubsub
+}
+
+func (p *SimpleGrainPool[V]) SetPubSub(pubsub *PubSub) {
+	p.pubsub = pubsub
+}
+
+func (p *SimpleGrainPool[V]) Publish(event Event) {
+	if p.pubsub != nil {
+		p.pubsub.Publish(event)
+	}
+}
+
+// Close notifies remotes that this host is shutting down.
+func (p *SimpleGrainPool[V]) Close() {
+
+	p.forAllHosts(func(rh Host) {
+		rh.Close()
+	})
+
+	if p.purgeTicker != nil {
+		p.purgeTicker.Stop()
+	}
+}

pkg/actor/state.go

@@ -0,0 +1,98 @@
+package actor
+
+import (
+	"bufio"
+	"encoding/json"
+	"errors"
+	"io"
+	"time"
+
+	"github.com/gogo/protobuf/proto"
+)
+
+type StateStorage struct {
+	registry MutationRegistry
+}
+
+type StorageEvent struct {
+	Type      string        `json:"type"`
+	TimeStamp time.Time     `json:"timestamp"`
+	Mutation  proto.Message `json:"mutation"`
+}
+
+type rawEvent struct {
+	Type      string          `json:"type"`
+	TimeStamp time.Time       `json:"timestamp"`
+	Mutation  json.RawMessage `json:"mutation"`
+}
+
+func NewState(registry MutationRegistry) *StateStorage {
+	return &StateStorage{
+		registry: registry,
+	}
+}
+
+var ErrUnknownType = errors.New("unknown type")
+
+func (s *StateStorage) Load(r io.Reader, onMessage func(msg proto.Message)) error {
+	var err error
+	var evt *StorageEvent
+	scanner := bufio.NewScanner(r)
+	for err == nil {
+		evt, err = s.Read(scanner)
+		if err == nil {
+			onMessage(evt.Mutation)
+		}
+	}
+	if err == io.EOF {
+		return nil
+	}
+	return err
+}
+
+func (s *StateStorage) Append(io io.Writer, mutation proto.Message, timeStamp time.Time) error {
+	typeName, ok := s.registry.GetTypeName(mutation)
+	if !ok {
+		return ErrUnknownType
+	}
+	event := &StorageEvent{
+		Type:      typeName,
+		TimeStamp: timeStamp,
+		Mutation:  mutation,
+	}
+	jsonBytes, err := json.Marshal(event)
+	if err != nil {
+		return err
+	}
+	if _, err := io.Write(jsonBytes); err != nil {
+		return err
+	}
+	io.Write([]byte("\n"))
+	return nil
+}
+
+func (s *StateStorage) Read(r *bufio.Scanner) (*StorageEvent, error) {
+	var event rawEvent
+
+	if r.Scan() {
+		b := r.Bytes()
+		err := json.Unmarshal(b, &event)
+		if err != nil {
+			return nil, err
+		}
+		typeName := event.Type
+		mutation, ok := s.registry.Create(typeName)
+		if !ok {
+			return nil, ErrUnknownType
+		}
+		if err := json.Unmarshal(event.Mutation, mutation); err != nil {
+			return nil, err
+		}
+		return &StorageEvent{
+			Type:      typeName,
+			TimeStamp: event.TimeStamp,
+			Mutation:  mutation,
+		}, r.Err()
+	}
+	return nil, io.EOF
+}

pkg/cart/cart-grain.go

@@ -0,0 +1,327 @@
+package cart
+
+import (
+	"encoding/json"
+	"slices"
+	"strings"
+	"sync"
+	"time"
+
+	"git.tornberg.me/go-cart-actor/pkg/actor"
+	messages "git.tornberg.me/go-cart-actor/pkg/messages"
+	"git.tornberg.me/go-cart-actor/pkg/voucher"
+)
+
+// Legacy padded [16]byte CartId and its helper methods removed.
+// Unified CartId (uint64 with base62 string form) now defined in cart_id.go.
+
+type StockStatus int
+
+type ItemMeta struct {
+	Name       string  `json:"name"`
+	Brand      string  `json:"brand,omitempty"`
+	Category   string  `json:"category,omitempty"`
+	Category2  string  `json:"category2,omitempty"`
+	Category3  string  `json:"category3,omitempty"`
+	Category4  string  `json:"category4,omitempty"`
+	Category5  string  `json:"category5,omitempty"`
+	SellerId   string  `json:"sellerId,omitempty"`
+	SellerName string  `json:"sellerName,omitempty"`
+	Image      string  `json:"image,omitempty"`
+	Outlet     *string `json:"outlet,omitempty"`
+}
+
+type CartItem struct {
+	Id          uint32  `json:"id"`
+	ItemId      uint32  `json:"itemId,omitempty"`
+	ParentId    *uint32 `json:"parentId,omitempty"`
+	Sku         string  `json:"sku"`
+	Price       Price   `json:"price"`
+	TotalPrice  Price   `json:"totalPrice"`
+	OrgPrice    *Price  `json:"orgPrice,omitempty"`
+	Tax         int
+	Stock       StockStatus `json:"stock"`
+	Quantity    int         `json:"qty"`
+	Discount    *Price      `json:"discount,omitempty"`
+	Disclaimer  string      `json:"disclaimer,omitempty"`
+	ArticleType string      `json:"type,omitempty"`
+	StoreId     *string     `json:"storeId,omitempty"`
+	Meta        *ItemMeta   `json:"meta,omitempty"`
+	SaleStatus  string      `json:"saleStatus"`
+}
+
+type CartDelivery struct {
+	Id          uint32                `json:"id"`
+	Provider    string                `json:"provider"`
+	Price       Price                 `json:"price"`
+	Items       []uint32              `json:"items"`
+	PickupPoint *messages.PickupPoint `json:"pickupPoint,omitempty"`
+}
+
+type CartNotification struct {
+	LinkedId int    `json:"id"`
+	Provider string `json:"provider"`
+	Title    string `json:"title"`
+	Content  string `json:"content"`
+}
+
+type SubscriptionDetails struct {
+	Id           string          `json:"id,omitempty"`
+	Version      uint16          `json:"version"`
+	OfferingCode string          `json:"offeringCode,omitempty"`
+	SigningType  string          `json:"signingType,omitempty"`
+	Meta         json.RawMessage `json:"data,omitempty"`
+}
+
+type CartGrain struct {
+	mu                  sync.RWMutex
+	lastItemId          uint32
+	lastDeliveryId      uint32
+	lastVoucherId       uint32
+	lastAccess          time.Time
+	lastChange          time.Time // unix seconds of last successful mutation (replay sets from event ts)
+	userId              string
+	InventoryReserved   bool                            `json:"inventoryReserved"`
+	Id                  CartId                          `json:"id"`
+	Items               []*CartItem                     `json:"items"`
+	TotalPrice          *Price                          `json:"totalPrice"`
+	TotalDiscount       *Price                          `json:"totalDiscount"`
+	Deliveries          []*CartDelivery                 `json:"deliveries,omitempty"`
+	Processing          bool                            `json:"processing"`
+	PaymentInProgress   bool                            `json:"paymentInProgress"`
+	OrderReference      string                          `json:"orderReference,omitempty"`
+	PaymentStatus       string                          `json:"paymentStatus,omitempty"`
+	Vouchers            []*Voucher                      `json:"vouchers,omitempty"`
+	Notifications       []CartNotification              `json:"cartNotification,omitempty"`
+	SubscriptionDetails map[string]*SubscriptionDetails `json:"subscriptionDetails,omitempty"`
+}
+
+type Voucher struct {
+	Code        string   `json:"code"`
+	Applied     bool     `json:"applied"`
+	Rules       []string `json:"rules"`
+	Description string   `json:"description,omitempty"`
+	Id          uint32   `json:"id"`
+	Value       int64    `json:"value"`
+}
+
+func (v *Voucher) AppliesTo(cart *CartGrain) ([]*CartItem, bool) {
+	// No rules -> applies to entire cart
+	if len(v.Rules) == 0 {
+		return cart.Items, true
+	}
+
+	// Build evaluation context once
+	ctx := voucher.EvalContext{
+		Items:        make([]voucher.Item, 0, len(cart.Items)),
+		CartTotalInc: 0,
+	}
+
+	if cart.TotalPrice != nil {
+		ctx.CartTotalInc = cart.TotalPrice.IncVat
+	}
+
+	for _, it := range cart.Items {
+		category := ""
+		if it.Meta != nil {
+			category = it.Meta.Category
+		}
+		ctx.Items = append(ctx.Items, voucher.Item{
+			Sku:       it.Sku,
+			Category:  category,
+			UnitPrice: it.Price.IncVat,
+		})
+	}
+
+	// All voucher rules must pass (logical AND)
+	for _, expr := range v.Rules {
+
+		if expr == "" {
+			// Empty condition treated as pass (acts like a comment / placeholder)
+			continue
+		}
+		rs, err := voucher.ParseRules(expr)
+		if err != nil {
+			// Fail closed on parse error
+			return nil, false
+		}
+		if !rs.Applies(ctx) {
+			return nil, false
+		}
+	}
+
+	return cart.Items, true
+}
+
+func NewCartGrain(id uint64, ts time.Time) *CartGrain {
+	return &CartGrain{
+		lastItemId:          0,
+		lastDeliveryId:      0,
+		lastVoucherId:       0,
+		lastAccess:          ts,
+		lastChange:          ts,
+		TotalDiscount:       NewPrice(),
+		Vouchers:            []*Voucher{},
+		Deliveries:          []*CartDelivery{},
+		Id:                  CartId(id),
+		Items:               []*CartItem{},
+		TotalPrice:          NewPrice(),
+		SubscriptionDetails: make(map[string]*SubscriptionDetails),
+	}
+}
+
+func (c *CartGrain) GetId() uint64 {
+	return uint64(c.Id)
+}
+
+func (c *CartGrain) GetLastChange() time.Time {
+	return c.lastChange
+}
+
+func (c *CartGrain) GetLastAccess() time.Time {
+	return c.lastAccess
+}
+
+func (c *CartGrain) GetCurrentState() (*CartGrain, error) {
+	c.lastAccess = time.Now()
+	return c, nil
+}
+
+// Notify handles incoming events, e.g., inventory changes.
+func (c *CartGrain) Notify(event actor.Event) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	// Example: if event is inventory change for a SKU in the cart
+	if strings.HasPrefix(event.Topic, "inventory:") {
+		sku := strings.TrimPrefix(event.Topic, "inventory:")
+		for _, item := range c.Items {
+			if item.Sku == sku {
+				// Update stock status based on payload, e.g., if payload is bool available
+				if available, ok := event.Payload.(bool); ok {
+					if available {
+						item.Stock = StockStatus(1) // assuming 1 is in stock
+					} else {
+						item.Stock = StockStatus(0) // out of stock
+					}
+				}
+				break
+			}
+		}
+	}
+}
+
+func (c *CartGrain) UpdateSubscriptions(pubsub *actor.PubSub) {
+	pubsub.UnsubscribeAll(c.GetId())
+	skuSet := make(map[string]bool)
+	for _, item := range c.Items {
+		skuSet[item.Sku] = true
+	}
+	for sku := range skuSet {
+		pubsub.Subscribe("inventory:"+sku, c.GetId())
+	}
+}
+
+func (c *CartGrain) GetState() ([]byte, error) {
+	return json.Marshal(c)
+}
+
+func (c *CartGrain) ItemsWithDelivery() []uint32 {
+	ret := make([]uint32, 0, len(c.Items))
+	for _, item := range c.Items {
+		for _, delivery := range c.Deliveries {
+			for _, id := range delivery.Items {
+				if item.Id == id {
+					ret = append(ret, id)
+				}
+			}
+		}
+	}
+	return ret
+}
+
+func (c *CartGrain) ItemsWithoutDelivery() []uint32 {
+	ret := make([]uint32, 0, len(c.Items))
+	hasDelivery := c.ItemsWithDelivery()
+	for _, item := range c.Items {
+		found := slices.Contains(hasDelivery, item.Id)
+
+		if !found {
+			ret = append(ret, item.Id)
+		}
+	}
+	return ret
+}
+
+func (c *CartGrain) FindItemWithSku(sku string) (*CartItem, bool) {
+	c.mu.RLock()
+	defer c.mu.RUnlock()
+	for _, item := range c.Items {
+		if item.Sku == sku {
+			return item, true
+		}
+	}
+	return nil, false
+}
+
+// func (c *CartGrain) Apply(content proto.Message, isReplay bool) (*CartGrain, error) {
+
+// 	updated, err := ApplyRegistered(c, content)
+// 	if err != nil {
+// 		if err == ErrMutationNotRegistered {
+// 			return nil, fmt.Errorf("unsupported mutation type %T (not registered)", content)
+// 		}
+// 		return nil, err
+// 	}
+
+// 	// Sliding TTL: update lastChange only for non-replay successful mutations.
+// 	if updated != nil && !isReplay {
+// 		c.lastChange = time.Now()
+// 		c.lastAccess = time.Now()
+// 		go AppendCartEvent(c.Id, content)
+// 	}
+
+// 	return updated, nil
+// }
+
+func (c *CartGrain) UpdateTotals() {
+	c.TotalPrice = NewPrice()
+	c.TotalDiscount = NewPrice()
+
+	for _, item := range c.Items {
+		rowTotal := MultiplyPrice(item.Price, int64(item.Quantity))
+
+		if item.OrgPrice != nil {
+			diff := NewPrice()
+			diff.Add(*item.OrgPrice)
+			diff.Subtract(item.Price)
+			diff.Multiply(int64(item.Quantity))
+			//rowTotal.Subtract(*diff)
+			item.Discount = diff
+			if diff.IncVat > 0 {
+				c.TotalDiscount.Add(*diff)
+			}
+		}
+
+		item.TotalPrice = *rowTotal
+
+		c.TotalPrice.Add(*rowTotal)
+
+	}
+	for _, delivery := range c.Deliveries {
+		c.TotalPrice.Add(delivery.Price)
+	}
+	for _, voucher := range c.Vouchers {
+		_, ok := voucher.AppliesTo(c)
+		voucher.Applied = false
+		if ok {
+			value := NewPriceFromIncVat(voucher.Value, 25)
+			if c.TotalPrice.IncVat <= value.IncVat {
+				// don't apply discounts to more than the total price
+				continue
+			}
+			voucher.Applied = true
+			c.TotalDiscount.Add(*value)
+			c.TotalPrice.Subtract(*value)
+		}
+	}
+}

pkg/cart/cart-mutation-helper.go

@@ -0,0 +1,57 @@
+package cart
+
+import (
+	"git.tornberg.me/go-cart-actor/pkg/actor"
+	messages "git.tornberg.me/go-cart-actor/pkg/messages"
+)
+
+func NewCartMultationRegistry() actor.MutationRegistry {
+
+	reg := actor.NewMutationRegistry()
+	reg.RegisterMutations(
+		actor.NewMutation(AddItem, func() *messages.AddItem {
+			return &messages.AddItem{}
+		}),
+		actor.NewMutation(ChangeQuantity, func() *messages.ChangeQuantity {
+			return &messages.ChangeQuantity{}
+		}),
+		actor.NewMutation(RemoveItem, func() *messages.RemoveItem {
+			return &messages.RemoveItem{}
+		}),
+		actor.NewMutation(InitializeCheckout, func() *messages.InitializeCheckout {
+			return &messages.InitializeCheckout{}
+		}),
+		actor.NewMutation(OrderCreated, func() *messages.OrderCreated {
+			return &messages.OrderCreated{}
+		}),
+		actor.NewMutation(RemoveDelivery, func() *messages.RemoveDelivery {
+			return &messages.RemoveDelivery{}
+		}),
+		actor.NewMutation(SetDelivery, func() *messages.SetDelivery {
+			return &messages.SetDelivery{}
+		}),
+		actor.NewMutation(SetPickupPoint, func() *messages.SetPickupPoint {
+			return &messages.SetPickupPoint{}
+		}),
+		actor.NewMutation(ClearCart, func() *messages.ClearCartRequest {
+			return &messages.ClearCartRequest{}
+		}),
+		actor.NewMutation(AddVoucher, func() *messages.AddVoucher {
+			return &messages.AddVoucher{}
+		}),
+		actor.NewMutation(RemoveVoucher, func() *messages.RemoveVoucher {
+			return &messages.RemoveVoucher{}
+		}),
+		actor.NewMutation(UpsertSubscriptionDetails, func() *messages.UpsertSubscriptionDetails {
+			return &messages.UpsertSubscriptionDetails{}
+		}),
+		actor.NewMutation(InventoryReserved, func() *messages.InventoryReserved {
+			return &messages.InventoryReserved{}
+		}),
+		actor.NewMutation(PreConditionFailed, func() *messages.PreConditionFailed {
+			return &messages.PreConditionFailed{}
+		}),
+	)
+	return reg
+
+}

pkg/cart/cart_grain_totals_test.go

@@ -0,0 +1,48 @@
+package cart
+
+import (
+	"testing"
+)
+
+// helper to create a cart grain with items and deliveries
+func newTestCart() *CartGrain {
+	return &CartGrain{Items: []*CartItem{}, Deliveries: []*CartDelivery{}, Vouchers: []*Voucher{}, Notifications: []CartNotification{}}
+}
+
+func TestCartGrainUpdateTotalsBasic(t *testing.T) {
+	c := newTestCart()
+	// Item1 price 1250 (ex 1000 vat 250) org price higher -> discount 200 per unit
+	item1Price := Price{IncVat: 1250, VatRates: map[float32]int64{25: 250}}
+	item1Org := &Price{IncVat: 1500, VatRates: map[float32]int64{25: 300}}
+	item2Price := Price{IncVat: 2000, VatRates: map[float32]int64{25: 400}}
+	c.Items = []*CartItem{
+		{Id: 1, Price: item1Price, OrgPrice: item1Org, Quantity: 2},
+		{Id: 2, Price: item2Price, OrgPrice: &item2Price, Quantity: 1},
+	}
+	deliveryPrice := Price{IncVat: 4900, VatRates: map[float32]int64{25: 980}}
+	c.Deliveries = []*CartDelivery{{Id: 1, Price: deliveryPrice, Items: []uint32{1, 2}}}
+
+	c.UpdateTotals()
+
+	// Expected totals: sum inc vat of items * qty plus delivery
+	// item1 total inc = 1250*2 = 2500
+	// item2 total inc = 2000*1 = 2000
+	// delivery inc = 4900
+	expectedInc := int64(2500 + 2000 + 4900)
+	if c.TotalPrice.IncVat != expectedInc {
+		t.Fatalf("TotalPrice IncVat expected %d got %d", expectedInc, c.TotalPrice.IncVat)
+	}
+
+	// Discount: current implementation computes (OrgPrice - Price) ignoring quantity -> 1500-1250=250
+	if c.TotalDiscount.IncVat != 500 {
+		t.Fatalf("TotalDiscount expected 500 got %d", c.TotalDiscount.IncVat)
+	}
+}
+
+func TestCartGrainUpdateTotalsNoItems(t *testing.T) {
+	c := newTestCart()
+	c.UpdateTotals()
+	if c.TotalPrice.IncVat != 0 || c.TotalDiscount.IncVat != 0 {
+		t.Fatalf("expected zero totals got %+v", c)
+	}
+}

pkg/cart/cart_id.go

@@ -0,0 +1,159 @@
+package cart
+
+import (
+	"crypto/rand"
+	"encoding/json"
+	"fmt"
+)
+
+// cart_id.go
+//
+// Breaking change:
+//   Unified cart identifier as a raw 64-bit unsigned integer (type CartId uint64).
+//   External textual representation: base62 (0-9 A-Z a-z), shortest possible
+//   encoding for 64 bits (max 11 characters, since 62^11 > 2^64).
+//
+// Rationale:
+//   - Replaces legacy fixed [16]byte padded string and transitional CartID wrapper.
+//   - Provides compact, URL/cookie-friendly identifiers.
+//   - O(1) hashing and minimal memory footprint.
+//   - 64 bits of crypto randomness => negligible collision probability at realistic scale.
+//
+// Public API:
+//   type CartId uint64
+//   func NewCartId() (CartId, error)
+//   func MustNewCartId() CartId
+//   func ParseCartId(string) (CartId, bool)
+//   func MustParseCartId(string) CartId
+//   (CartId).String() string
+//   (CartId).MarshalJSON() / UnmarshalJSON()
+//
+// NOTE:
+//   All legacy helpers (UpgradeLegacyCartId, Fallback hashing, Canonicalize variants,
+//   CartIDToLegacy, LegacyToCartID) have been removed as part of the breaking change.
+//
+// ---------------------------------------------------------------------------
+
+type CartId uint64
+
+const base62Alphabet = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
+
+// Reverse lookup (0xFF marks invalid)
+var base62Rev [256]byte
+
+func init() {
+	for i := range base62Rev {
+		base62Rev[i] = 0xFF
+	}
+	for i := 0; i < len(base62Alphabet); i++ {
+		base62Rev[base62Alphabet[i]] = byte(i)
+	}
+}
+
+// String returns the canonical base62 encoding of the 64-bit id.
+func (id CartId) String() string {
+	return encodeBase62(uint64(id))
+}
+
+// MarshalJSON encodes the cart id as a JSON string.
+func (id CartId) MarshalJSON() ([]byte, error) {
+	return json.Marshal(id.String())
+}
+
+// UnmarshalJSON decodes a cart id from a JSON string containing base62 text.
+func (id *CartId) UnmarshalJSON(data []byte) error {
+	var s string
+	if err := json.Unmarshal(data, &s); err != nil {
+		return err
+	}
+	parsed, ok := ParseCartId(s)
+	if !ok {
+		return fmt.Errorf("invalid cart id: %q", s)
+	}
+	*id = parsed
+	return nil
+}
+
+// NewCartId generates a new cryptographically random non-zero 64-bit id.
+func NewCartId() (CartId, error) {
+	var b [8]byte
+	if _, err := rand.Read(b[:]); err != nil {
+		return 0, fmt.Errorf("NewCartId: %w", err)
+	}
+	u := (uint64(b[0]) << 56) |
+		(uint64(b[1]) << 48) |
+		(uint64(b[2]) << 40) |
+		(uint64(b[3]) << 32) |
+		(uint64(b[4]) << 24) |
+		(uint64(b[5]) << 16) |
+		(uint64(b[6]) << 8) |
+		uint64(b[7])
+	if u == 0 {
+		// Extremely unlikely; regenerate once to avoid "0" identifier if desired.
+		return NewCartId()
+	}
+	return CartId(u), nil
+}
+
+// MustNewCartId panics if generation fails.
+func MustNewCartId() CartId {
+	id, err := NewCartId()
+	if err != nil {
+		panic(err)
+	}
+	return id
+}
+
+// ParseCartId parses a base62 string into a CartId.
+// Returns (0,false) for invalid input.
+func ParseCartId(s string) (CartId, bool) {
+	// Accept length 1..11 (11 sufficient for 64 bits). Reject >11 immediately.
+	// Provide a slightly looser upper bound (<=16) only if you anticipate future
+	// extensions; here we stay strict.
+	if len(s) == 0 || len(s) > 11 {
+		return 0, false
+	}
+	u, ok := decodeBase62(s)
+	if !ok {
+		return 0, false
+	}
+	return CartId(u), true
+}
+
+// MustParseCartId panics on invalid base62 input.
+func MustParseCartId(s string) CartId {
+	id, ok := ParseCartId(s)
+	if !ok {
+		panic(fmt.Sprintf("invalid cart id: %q", s))
+	}
+	return id
+}
+
+// encodeBase62 converts a uint64 to base62 (shortest form).
+func encodeBase62(u uint64) string {
+	if u == 0 {
+		return "0"
+	}
+	var buf [11]byte
+	i := len(buf)
+	for u > 0 {
+		i--
+		buf[i] = base62Alphabet[u%62]
+		u /= 62
+	}
+	return string(buf[i:])
+}
+
+// decodeBase62 converts base62 text to uint64.
+func decodeBase62(s string) (uint64, bool) {
+	var v uint64
+	for i := 0; i < len(s); i++ {
+		c := s[i]
+		d := base62Rev[c]
+		if d == 0xFF {
+			return 0, false
+		}
+		v = v*62 + uint64(d)
+	}
+	return v, true
+}

pkg/cart/cart_id_test.go

@@ -0,0 +1,185 @@
+package cart
+
+import (
+	"encoding/json"
+	"fmt"
+	"testing"
+)
+
+// TestNewCartIdUniqueness generates many ids and checks for collisions.
+func TestNewCartIdUniqueness(t *testing.T) {
+	const n = 20000
+	seen := make(map[string]struct{}, n)
+	for i := 0; i < n; i++ {
+		id, err := NewCartId()
+		if err != nil {
+			t.Fatalf("NewCartId error: %v", err)
+		}
+		s := id.String()
+		if _, exists := seen[s]; exists {
+			t.Fatalf("duplicate id encountered: %s", s)
+		}
+		seen[s] = struct{}{}
+		if s == "" {
+			t.Fatalf("empty string representation for id %d", id)
+		}
+		if len(s) > 11 {
+			t.Fatalf("encoded id length exceeds 11 chars: %s (%d)", s, len(s))
+		}
+		if id == 0 {
+			// We force regeneration on zero, extremely unlikely but test guards intent.
+			t.Fatalf("zero id generated (should be regenerated)")
+		}
+	}
+}
+
+// TestParseCartIdRoundTrip ensures parse -> string -> parse is stable.
+func TestParseCartIdRoundTrip(t *testing.T) {
+	id := MustNewCartId()
+	txt := id.String()
+	parsed, ok := ParseCartId(txt)
+	if !ok {
+		t.Fatalf("ParseCartId failed for valid text %q", txt)
+	}
+	if parsed != id {
+		t.Fatalf("round trip mismatch: original=%d parsed=%d txt=%s", id, parsed, txt)
+	}
+}
+
+// TestParseCartIdInvalid covers invalid inputs.
+func TestParseCartIdInvalid(t *testing.T) {
+	invalid := []string{
+		"",               // empty
+		" ",              // space
+		"01234567890abc", // >11 chars
+		"!!!!",           // invalid chars
+		"-underscore-",   // invalid chars
+		"abc_def",        // underscore invalid for base62
+		"0123456789ABCD", // 14 chars
+	}
+	for _, s := range invalid {
+		if _, ok := ParseCartId(s); ok {
+			t.Fatalf("expected parse failure for %q", s)
+		}
+	}
+}
+
+// TestMustParseCartIdPanics verifies panic behavior for invalid input.
+func TestMustParseCartIdPanics(t *testing.T) {
+	defer func() {
+		if r := recover(); r == nil {
+			t.Fatalf("expected panic for invalid MustParseCartId input")
+		}
+	}()
+	_ = MustParseCartId("not*base62")
+}
+
+// TestJSONMarshalUnmarshalCartId verifies JSON round trip.
+func TestJSONMarshalUnmarshalCartId(t *testing.T) {
+	id := MustNewCartId()
+	data, err := json.Marshal(struct {
+		Cart CartId `json:"cart"`
+	}{Cart: id})
+	if err != nil {
+		t.Fatalf("marshal error: %v", err)
+	}
+	var out struct {
+		Cart CartId `json:"cart"`
+	}
+	if err := json.Unmarshal(data, &out); err != nil {
+		t.Fatalf("unmarshal error: %v", err)
+	}
+	if out.Cart != id {
+		t.Fatalf("JSON round trip mismatch: have %d got %d", id, out.Cart)
+	}
+}
+
+// TestBase62LengthBound checks worst-case length (near max uint64).
+func TestBase62LengthBound(t *testing.T) {
+	// Largest uint64
+	const maxU64 = ^uint64(0)
+	s := encodeBase62(maxU64)
+	if len(s) > 11 {
+		t.Fatalf("max uint64 encoded length > 11: %d (%s)", len(s), s)
+	}
+	dec, ok := decodeBase62(s)
+	if !ok || dec != maxU64 {
+		t.Fatalf("decode failed for max uint64: ok=%v dec=%d want=%d", ok, dec, maxU64)
+	}
+}
+
+// TestZeroEncoding ensures zero value encodes to "0" and parses back.
+func TestZeroEncoding(t *testing.T) {
+	if s := encodeBase62(0); s != "0" {
+		t.Fatalf("encodeBase62(0) expected '0', got %q", s)
+	}
+	v, ok := decodeBase62("0")
+	if !ok || v != 0 {
+		t.Fatalf("decodeBase62('0') failed: ok=%v v=%d", ok, v)
+	}
+	if _, ok := ParseCartId("0"); !ok {
+		t.Fatalf("ParseCartId(\"0\") should succeed")
+	}
+}
+
+// TestSequentialParse ensures sequentially generated ids parse correctly.
+func TestSequentialParse(t *testing.T) {
+	for i := 0; i < 1000; i++ {
+		id := MustNewCartId()
+		txt := id.String()
+		parsed, ok := ParseCartId(txt)
+		if !ok || parsed != id {
+			t.Fatalf("sequential parse mismatch: idx=%d orig=%d parsed=%d txt=%s", i, id, parsed, txt)
+		}
+	}
+}
+
+// BenchmarkNewCartId measures generation performance.
+func BenchmarkNewCartId(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		if _, err := NewCartId(); err != nil {
+			b.Fatalf("NewCartId error: %v", err)
+		}
+	}
+}
+
+// BenchmarkEncodeBase62 measures encoding performance.
+func BenchmarkEncodeBase62(b *testing.B) {
+	// Precompute sample values
+	samples := make([]uint64, 1024)
+	for i := range samples {
+		// Spread bits without crypto randomness overhead
+		samples[i] = (uint64(i) << 53) ^ (uint64(i) * 0x9E3779B185EBCA87)
+	}
+	b.ResetTimer()
+	var sink string
+	for i := 0; i < b.N; i++ {
+		sink = encodeBase62(samples[i%len(samples)])
+	}
+	_ = sink
+}
+
+// BenchmarkDecodeBase62 measures decoding performance.
+func BenchmarkDecodeBase62(b *testing.B) {
+	encoded := make([]string, 1024)
+	for i := range encoded {
+		encoded[i] = encodeBase62((uint64(i) << 32) | uint64(i))
+	}
+	b.ResetTimer()
+	var sum uint64
+	for i := 0; i < b.N; i++ {
+		v, ok := decodeBase62(encoded[i%len(encoded)])
+		if !ok {
+			b.Fatalf("decode failure for %s", encoded[i%len(encoded)])
+		}
+		sum ^= v
+	}
+	_ = sum
+}
+
+// ExampleCartIdString documents usage of CartId string form.
+func ExampleCartId_string() {
+	id := MustNewCartId()
+	fmt.Println(len(id.String()) <= 11) // outputs true
+	// Output: true
+}

pkg/cart/mutation_add_item.go

@@ -0,0 +1,103 @@
+package cart
+
+import (
+	"fmt"
+
+	messages "git.tornberg.me/go-cart-actor/pkg/messages"
+)
+
+// mutation_add_item.go
+//
+// Registers the AddItem cart mutation in the generic mutation registry.
+// This replaces the legacy switch-based logic previously found in CartGrain.Apply.
+//
+// Behavior:
+//   * Validates quantity > 0
+//   * If an item with same SKU exists -> increases quantity
+//   * Else creates a new CartItem with computed tax amounts
+//   * Totals recalculated automatically via WithTotals()
+//
+// NOTE: Any future field additions in messages.AddItem that affect pricing / tax
+// must keep this handler in sync.
+
+func AddItem(g *CartGrain, m *messages.AddItem) error {
+	if m == nil {
+		return fmt.Errorf("AddItem: nil payload")
+	}
+	if m.Quantity < 1 {
+		return fmt.Errorf("AddItem: invalid quantity %d", m.Quantity)
+	}
+
+	// Merge with any existing item having same SKU and matching StoreId (including both nil).
+	for _, existing := range g.Items {
+		if existing.Sku != m.Sku {
+			continue
+		}
+		sameStore := (existing.StoreId == nil && m.StoreId == nil) ||
+			(existing.StoreId != nil && m.StoreId != nil && *existing.StoreId == *m.StoreId)
+		if !sameStore {
+			continue
+		}
+		existing.Quantity += int(m.Quantity)
+		existing.Stock = StockStatus(m.Stock)
+		// If existing had nil store but new has one, adopt it.
+		if existing.StoreId == nil && m.StoreId != nil {
+			existing.StoreId = m.StoreId
+		}
+		return nil
+	}
+
+	g.mu.Lock()
+	defer g.mu.Unlock()
+
+	g.lastItemId++
+	taxRate := float32(25.0)
+	if m.Tax > 0 {
+		taxRate = float32(int(m.Tax) / 100)
+	}
+
+	pricePerItem := NewPriceFromIncVat(m.Price, taxRate)
+
+	g.Items = append(g.Items, &CartItem{
+		Id:       g.lastItemId,
+		ItemId:   uint32(m.ItemId),
+		Quantity: int(m.Quantity),
+		Sku:      m.Sku,
+		Tax:      int(taxRate * 100),
+		Meta: &ItemMeta{
+			Name:       m.Name,
+			Image:      m.Image,
+			Brand:      m.Brand,
+			Category:   m.Category,
+			Category2:  m.Category2,
+			Category3:  m.Category3,
+			Category4:  m.Category4,
+			Category5:  m.Category5,
+			Outlet:     m.Outlet,
+			SellerId:   m.SellerId,
+			SellerName: m.SellerName,
+		},
+		SaleStatus: m.SaleStatus,
+		ParentId:   m.ParentId,
+
+		Price:      *pricePerItem,
+		TotalPrice: *MultiplyPrice(*pricePerItem, int64(m.Quantity)),
+
+		Stock:      StockStatus(m.Stock),
+		Disclaimer: m.Disclaimer,
+
+		OrgPrice:    getOrgPrice(m.OrgPrice, taxRate),
+		ArticleType: m.ArticleType,
+
+		StoreId: m.StoreId,
+	})
+	g.UpdateTotals()
+	return nil
+}
+
+func getOrgPrice(orgPrice int64, taxRate float32) *Price {
+	if orgPrice <= 0 {
+		return nil
+	}
+	return NewPriceFromIncVat(orgPrice, taxRate)
+}

pkg/cart/mutation_add_voucher.go

@@ -0,0 +1,66 @@
+package cart
+
+import (
+	"slices"
+
+	"git.tornberg.me/go-cart-actor/pkg/actor"
+	"git.tornberg.me/go-cart-actor/pkg/messages"
+)
+
+func RemoveVoucher(g *CartGrain, m *messages.RemoveVoucher) error {
+	if m == nil {
+		return &actor.MutationError{
+			Message:    "RemoveVoucher: nil payload",
+			Code:       1003,
+			StatusCode: 400,
+		}
+	}
+
+	if !slices.ContainsFunc(g.Vouchers, func(v *Voucher) bool {
+		return v.Id == m.Id
+	}) {
+		return &actor.MutationError{
+			Message:    "voucher not applied",
+			Code:       1004,
+			StatusCode: 400,
+		}
+	}
+
+	g.Vouchers = slices.DeleteFunc(g.Vouchers, func(v *Voucher) bool {
+		return v.Id == m.Id
+	})
+	g.UpdateTotals()
+	return nil
+}
+
+func AddVoucher(g *CartGrain, m *messages.AddVoucher) error {
+	if m == nil {
+		return &actor.MutationError{
+			Message:    "AddVoucher: nil payload",
+			Code:       1001,
+			StatusCode: 400,
+		}
+	}
+
+	if slices.ContainsFunc(g.Vouchers, func(v *Voucher) bool {
+		return v.Code == m.Code
+	}) {
+		return &actor.MutationError{
+			Message:    "voucher already applied",
+			Code:       1002,
+			StatusCode: 400,
+		}
+	}
+
+	g.lastVoucherId++
+	g.Vouchers = append(g.Vouchers, &Voucher{
+		Id:          g.lastVoucherId,
+		Applied:     false,
+		Description: m.Description,
+		Code:        m.Code,
+		Rules:       m.VoucherRules,
+		Value:       m.Value,
+	})
+	g.UpdateTotals()
+	return nil
+}

pkg/cart/mutation_change_quantity.go

@@ -0,0 +1,55 @@
+package cart
+
+import (
+	"fmt"
+
+	messages "git.tornberg.me/go-cart-actor/pkg/messages"
+)
+
+// mutation_change_quantity.go
+//
+// Registers the ChangeQuantity mutation.
+//
+// Behavior:
+//   - Locates an item by its cart-local line item Id (not source item_id).
+//   - If requested quantity <= 0 the line is removed.
+//   - Otherwise the line's Quantity field is updated.
+//   - Totals are recalculated (WithTotals).
+//
+// Error handling:
+//   - Returns an error if the item Id is not found.
+//   - Returns an error if payload is nil (defensive).
+//
+// Concurrency:
+//   - Uses the grain's RW-safe mutation pattern: we mutate in place under
+//     the grain's implicit expectation that higher layers control access.
+//     (If strict locking is required around every mutation, wrap logic in
+//     an explicit g.mu.Lock()/Unlock(), but current model mirrors prior code.)
+
+func ChangeQuantity(g *CartGrain, m *messages.ChangeQuantity) error {
+	if m == nil {
+		return fmt.Errorf("ChangeQuantity: nil payload")
+	}
+
+	foundIndex := -1
+	for i, it := range g.Items {
+		if it.Id == uint32(m.Id) {
+			foundIndex = i
+			break
+		}
+	}
+	if foundIndex == -1 {
+		return fmt.Errorf("ChangeQuantity: item id %d not found", m.Id)
+	}
+
+	if m.Quantity <= 0 {
+		// Remove the item
+		g.Items = append(g.Items[:foundIndex], g.Items[foundIndex+1:]...)
+		g.UpdateTotals()
+		return nil
+	}
+
+	g.Items[foundIndex].Quantity = int(m.Quantity)
+	g.UpdateTotals()
+	return nil
+}

pkg/cart/mutation_initialize_checkout.go

@@ -0,0 +1,44 @@
+package cart
+
+import (
+	"fmt"
+
+	messages "git.tornberg.me/go-cart-actor/pkg/messages"
+)
+
+// mutation_initialize_checkout.go
+//
+// Registers the InitializeCheckout mutation.
+// This mutation is invoked AFTER an external Klarna checkout session
+// has been successfully created or updated. It persists the Klarna
+// order reference / status and marks the cart as having a payment in progress.
+//
+// Behavior:
+//   - Sets OrderReference to the Klarna order ID (overwriting if already set).
+//   - Sets PaymentStatus to the current Klarna status.
+//   - Sets / updates PaymentInProgress flag.
+//   - Does NOT alter pricing or line items (so no totals recalculation).
+//
+// Validation:
+//   - Returns an error if payload is nil.
+//   - Returns an error if orderId is empty (integrity guard).
+//
+// Concurrency:
+//   - Relies on upstream mutation serialization for a single grain. If
+//     parallel checkout attempts are possible, add higher-level guards
+//     (e.g. reject if PaymentInProgress already true unless reusing
+//     the same OrderReference).
+
+func InitializeCheckout(g *CartGrain, m *messages.InitializeCheckout) error {
+	if m == nil {
+		return fmt.Errorf("InitializeCheckout: nil payload")
+	}
+	if m.OrderId == "" {
+		return fmt.Errorf("InitializeCheckout: missing orderId")
+	}
+
+	g.OrderReference = m.OrderId
+	g.PaymentStatus = m.Status
+	g.PaymentInProgress = m.PaymentInProgress
+	return nil
+}

pkg/cart/mutation_inventory_reserved.go

@@ -0,0 +1,8 @@
+package cart
+
+import "git.tornberg.me/go-cart-actor/pkg/messages"
+
+func InventoryReserved(g *CartGrain, m *messages.InventoryReserved) error {
+	g.InventoryReserved = true
+	return nil
+}

pkg/cart/mutation_order_created.go

@@ -0,0 +1,48 @@
+package cart
+
+import (
+	"fmt"
+
+	messages "git.tornberg.me/go-cart-actor/pkg/messages"
+)
+
+// mutation_order_created.go
+//
+// Registers the OrderCreated mutation.
+//
+// This mutation represents the completion (or state transition) of an order
+// initiated earlier via InitializeCheckout / external Klarna processing.
+// It finalizes (or updates) the cart's order metadata.
+//
+// Behavior:
+//   - Validates payload non-nil and OrderId not empty.
+//   - Sets (or overwrites) OrderReference with the provided OrderId.
+//   - Sets PaymentStatus from payload.Status.
+//   - Marks PaymentInProgress = false (checkout flow finished / acknowledged).
+//   - Does NOT adjust monetary totals (no WithTotals()).
+//
+// Notes / Future Extensions:
+//   - If multiple order completion events can arrive (e.g., retries / webhook
+//     replays), this handler is idempotent: it simply overwrites fields.
+//   - If you need to guard against conflicting order IDs, add a check:
+//     if g.OrderReference != "" && g.OrderReference != m.OrderId { ... }
+//   - Add audit logging or metrics here if required.
+//
+// Concurrency:
+//   - Relies on the higher-level guarantee that Apply() calls are serialized
+//     per grain. If out-of-order events are possible, embed versioning or
+//     timestamps in the mutation and compare before applying changes.
+
+func OrderCreated(g *CartGrain, m *messages.OrderCreated) error {
+	if m == nil {
+		return fmt.Errorf("OrderCreated: nil payload")
+	}
+	if m.OrderId == "" {
+		return fmt.Errorf("OrderCreated: missing orderId")
+	}
+
+	g.OrderReference = m.OrderId
+	g.PaymentStatus = m.Status
+	g.PaymentInProgress = false
+	return nil
+}

pkg/cart/mutation_precondition.go

@@ -0,0 +1,7 @@
+package cart
+
+import messages "git.tornberg.me/go-cart-actor/pkg/messages"
+
+func PreConditionFailed(g *CartGrain, m *messages.PreConditionFailed) error {
+	return nil
+}

pkg/cart/mutation_remove_delivery.go

@@ -0,0 +1,49 @@
+package cart
+
+import (
+	"fmt"
+
+	messages "git.tornberg.me/go-cart-actor/pkg/messages"
+)
+
+// mutation_remove_delivery.go
+//
+// Registers the RemoveDelivery mutation.
+//
+// Behavior:
+//   - Removes the delivery entry whose Id == payload.Id.
+//   - If not found, returns an error.
+//   - Cart totals are recalculated (WithTotals) after removal.
+//   - Items previously associated with that delivery simply become "without delivery";
+//     subsequent delivery mutations can reassign them.
+//
+// Differences vs legacy:
+//   - Legacy logic decremented TotalPrice explicitly before recalculating.
+//     Here we rely solely on UpdateTotals() to recompute from remaining
+//     deliveries and items (simpler / single source of truth).
+//
+// Future considerations:
+//   - If delivery pricing logic changes (e.g., dynamic taxes per delivery),
+//     UpdateTotals() may need enhancement to incorporate delivery tax properly.
+
+func RemoveDelivery(g *CartGrain, m *messages.RemoveDelivery) error {
+	if m == nil {
+		return fmt.Errorf("RemoveDelivery: nil payload")
+	}
+	targetID := uint32(m.Id)
+	index := -1
+	for i, d := range g.Deliveries {
+		if d.Id == targetID {
+			index = i
+			break
+		}
+	}
+	if index == -1 {
+		return fmt.Errorf("RemoveDelivery: delivery id %d not found", m.Id)
+	}
+
+	// Remove delivery (order not preserved beyond necessity)
+	g.Deliveries = append(g.Deliveries[:index], g.Deliveries[index+1:]...)
+	g.UpdateTotals()
+	return nil
+}

pkg/cart/mutation_remove_item.go

@@ -0,0 +1,45 @@
+package cart
+
+import (
+	"fmt"
+
+	messages "git.tornberg.me/go-cart-actor/pkg/messages"
+)
+
+// mutation_remove_item.go
+//
+// Registers the RemoveItem mutation.
+//
+// Behavior:
+//   - Removes the cart line whose local cart line Id == payload.Id
+//   - If no such line exists returns an error
+//   - Recalculates cart totals (WithTotals)
+//
+// Notes:
+//   - This removes only the line item; any deliveries referencing the removed
+//     item are NOT automatically adjusted (mirrors prior logic). If future
+//     semantics require pruning delivery.item_ids you can extend this handler.
+//   - If multiple lines somehow shared the same Id (should not happen), only
+//     the first match would be removed—data integrity relies on unique line Ids.
+
+func RemoveItem(g *CartGrain, m *messages.RemoveItem) error {
+	if m == nil {
+		return fmt.Errorf("RemoveItem: nil payload")
+	}
+	targetID := uint32(m.Id)
+
+	index := -1
+	for i, it := range g.Items {
+		if it.Id == targetID {
+			index = i
+			break
+		}
+	}
+	if index == -1 {
+		return fmt.Errorf("RemoveItem: item id %d not found", m.Id)
+	}
+
+	g.Items = append(g.Items[:index], g.Items[index+1:]...)
+	g.UpdateTotals()
+	return nil
+}

pkg/cart/mutation_set_delivery.go

@@ -0,0 +1,96 @@
+package cart
+
+import (
+	"fmt"
+	"slices"
+
+	messages "git.tornberg.me/go-cart-actor/pkg/messages"
+)
+
+// mutation_set_delivery.go
+//
+// Registers the SetDelivery mutation.
+//
+// Semantics (mirrors legacy switch logic):
+//   - If the payload specifies an explicit list of item IDs (payload.Items):
+//   - Each referenced cart line must exist.
+//   - None of the referenced items may already belong to a delivery.
+//   - Only those items are associated with the new delivery.
+//   - If payload.Items is empty:
+//   - All items currently without any delivery are associated with the new delivery.
+//   - A new delivery line is created with:
+//   - Auto-incremented delivery ID (cart-local)
+//   - Provider from payload
+//   - Fixed price (currently hard-coded: 4900 minor units) – adjust as needed
+//   - Optional PickupPoint copied from payload
+//   - Cart totals are recalculated (WithTotals)
+//
+// Error cases:
+//   - Referenced item does not exist
+//   - Referenced item already has a delivery
+//   - No items qualify (resulting association set empty) -> returns error (prevents creating empty delivery)
+//
+// Concurrency:
+//   - Uses g.mu to protect lastDeliveryId increment and append to Deliveries slice.
+//     Item scans are read-only and performed outside the lock for simplicity;
+//     if stricter guarantees are needed, widen the lock section.
+//
+// Future extension points:
+//   - Variable delivery pricing (based on weight, distance, provider, etc.)
+//   - Validation of provider codes
+//   - Multi-currency delivery pricing
+
+func SetDelivery(g *CartGrain, m *messages.SetDelivery) error {
+	if m == nil {
+		return fmt.Errorf("SetDelivery: nil payload")
+	}
+	if m.Provider == "" {
+		return fmt.Errorf("SetDelivery: provider is empty")
+	}
+
+	withDelivery := g.ItemsWithDelivery()
+	targetItems := make([]uint32, 0)
+
+	if len(m.Items) == 0 {
+		// Use every item currently without a delivery
+		targetItems = append(targetItems, g.ItemsWithoutDelivery()...)
+	} else {
+		// Validate explicit list
+		for _, id64 := range m.Items {
+			id := uint32(id64)
+			found := false
+			for _, it := range g.Items {
+				if it.Id == id {
+					found = true
+					break
+				}
+			}
+			if !found {
+				return fmt.Errorf("SetDelivery: item id %d not found", id)
+			}
+			if slices.Contains(withDelivery, id) {
+				return fmt.Errorf("SetDelivery: item id %d already has a delivery", id)
+			}
+			targetItems = append(targetItems, id)
+		}
+	}
+
+	if len(targetItems) == 0 {
+		return fmt.Errorf("SetDelivery: no eligible items to attach")
+	}
+
+	// Append new delivery
+	g.mu.Lock()
+	g.lastDeliveryId++
+	newId := g.lastDeliveryId
+	g.Deliveries = append(g.Deliveries, &CartDelivery{
+		Id:          newId,
+		Provider:    m.Provider,
+		PickupPoint: m.PickupPoint,
+		Price:       *NewPriceFromIncVat(4900, 25.0),
+		Items:       targetItems,
+	})
+	g.mu.Unlock()
+
+	return nil
+}

pkg/cart/mutation_set_pickup_point.go

@@ -0,0 +1,62 @@
+package cart
+
+import (
+	"fmt"
+
+	messages "git.tornberg.me/go-cart-actor/pkg/messages"
+)
+
+// mutation_set_pickup_point.go
+//
+// Registers the SetPickupPoint mutation using the generic mutation registry.
+//
+// Semantics (mirrors original switch-based implementation):
+//   - Locate the delivery with Id == payload.DeliveryId
+//   - Set (or overwrite) its PickupPoint with the provided data
+//   - Does NOT alter pricing or taxes (so no totals recalculation required)
+//
+// Validation / Error Handling:
+//   - If payload is nil -> error
+//   - If DeliveryId not found -> error
+//
+// Concurrency:
+//   - Relies on the existing expectation that higher-level mutation routing
+//     serializes Apply() calls per grain; if stricter guarantees are needed,
+//     a delivery-level lock could be introduced later.
+//
+// Future Extensions:
+//   - Validate pickup point fields (country code, zip format, etc.)
+//   - Track history / audit of pickup point changes
+//   - Trigger delivery price adjustments (which would then require WithTotals()).
+
+func SetPickupPoint(g *CartGrain, m *messages.SetPickupPoint) error {
+	if m == nil {
+		return fmt.Errorf("SetPickupPoint: nil payload")
+	}
+
+	for _, d := range g.Deliveries {
+		if d.Id == uint32(m.DeliveryId) {
+			d.PickupPoint = &messages.PickupPoint{
+				Id:      m.Id,
+				Name:    m.Name,
+				Address: m.Address,
+				City:    m.City,
+				Zip:     m.Zip,
+				Country: m.Country,
+			}
+			return nil
+		}
+	}
+	return fmt.Errorf("SetPickupPoint: delivery id %d not found", m.DeliveryId)
+}
+
+func ClearCart(g *CartGrain, m *messages.ClearCartRequest) error {
+	if m == nil {
+		return fmt.Errorf("ClearCart: nil payload")
+	}
+	// maybe check if payment is done?
+	g.Deliveries = g.Deliveries[:0]
+	g.Items = g.Items[:0]
+	g.UpdateTotals()
+	return nil
+}

pkg/cart/mutation_test.go

@@ -0,0 +1,544 @@
+package cart
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"reflect"
+	"slices"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/gogo/protobuf/proto"
+	"google.golang.org/protobuf/types/known/anypb"
+
+	"git.tornberg.me/go-cart-actor/pkg/actor"
+	messages "git.tornberg.me/go-cart-actor/pkg/messages"
+)
+
+// ----------------------
+// Helper constructors
+// ----------------------
+
+func newTestGrain() *CartGrain {
+	return NewCartGrain(123, time.Now())
+}
+
+func newRegistry() actor.MutationRegistry {
+	return NewCartMultationRegistry()
+}
+
+func msgAddItem(sku string, price int64, qty int32, storePtr *string) *messages.AddItem {
+	return &messages.AddItem{
+		Sku:      sku,
+		Price:    price,
+		Quantity: qty,
+		// Tax left 0 -> handler uses default 25%
+		StoreId: storePtr,
+	}
+}
+
+func msgChangeQty(id uint32, qty int32) *messages.ChangeQuantity {
+	return &messages.ChangeQuantity{Id: id, Quantity: qty}
+}
+
+func msgRemoveItem(id uint32) *messages.RemoveItem {
+	return &messages.RemoveItem{Id: id}
+}
+
+func msgSetDelivery(provider string, items ...uint32) *messages.SetDelivery {
+	uitems := make([]uint32, len(items))
+	copy(uitems, items)
+	return &messages.SetDelivery{Provider: provider, Items: uitems}
+}
+
+func msgSetPickupPoint(deliveryId uint32, id string) *messages.SetPickupPoint {
+	return &messages.SetPickupPoint{
+		DeliveryId: deliveryId,
+		Id:         id,
+		Name:       ptr("Pickup"),
+		Address:    ptr("Street 1"),
+		City:       ptr("Town"),
+		Zip:        ptr("12345"),
+		Country:    ptr("SE"),
+	}
+}
+
+func msgClearCart() *messages.ClearCartRequest {
+	return &messages.ClearCartRequest{}
+}
+
+func msgAddVoucher(code string, value int64, rules ...string) *messages.AddVoucher {
+	return &messages.AddVoucher{Code: code, Value: value, VoucherRules: rules}
+}
+
+func msgRemoveVoucher(id uint32) *messages.RemoveVoucher {
+	return &messages.RemoveVoucher{Id: id}
+}
+
+func msgInitializeCheckout(orderId, status string, inProgress bool) *messages.InitializeCheckout {
+	return &messages.InitializeCheckout{OrderId: orderId, Status: status, PaymentInProgress: inProgress}
+}
+
+func msgOrderCreated(orderId, status string) *messages.OrderCreated {
+	return &messages.OrderCreated{OrderId: orderId, Status: status}
+}
+
+func ptr[T any](v T) *T { return &v }
+
+// ----------------------
+// Apply helpers
+// ----------------------
+
+func applyOne(t *testing.T, reg actor.MutationRegistry, g *CartGrain, msg proto.Message) actor.ApplyResult {
+	t.Helper()
+	results, err := reg.Apply(context.Background(), g, msg)
+	if err != nil {
+		t.Fatalf("unexpected registry-level error applying %T: %v", msg, err)
+	}
+	if len(results) != 1 {
+		t.Fatalf("expected exactly one ApplyResult, got %d", len(results))
+	}
+	return results[0]
+}
+
+// Expect success (nil error inside ApplyResult).
+func applyOK(t *testing.T, reg actor.MutationRegistry, g *CartGrain, msg proto.Message) {
+	t.Helper()
+	res := applyOne(t, reg, g, msg)
+	if res.Error != nil {
+		t.Fatalf("expected mutation %s (%T) to succeed, got error: %v", res.Type, msg, res.Error)
+	}
+}
+
+// Expect an error matching substring.
+func applyErrorContains(t *testing.T, reg actor.MutationRegistry, g *CartGrain, msg proto.Message, substr string) {
+	t.Helper()
+	res := applyOne(t, reg, g, msg)
+	if res.Error == nil {
+		t.Fatalf("expected error applying %T, got nil", msg)
+	}
+	if substr != "" && !strings.Contains(res.Error.Error(), substr) {
+		t.Fatalf("error mismatch, want substring %q got %q", substr, res.Error.Error())
+	}
+}
+
+// ----------------------
+// Tests
+// ----------------------
+
+func TestMutationRegistryCoverage(t *testing.T) {
+	reg := newRegistry()
+
+	expected := []string{
+		"AddItem",
+		"ChangeQuantity",
+		"RemoveItem",
+		"InitializeCheckout",
+		"OrderCreated",
+		"RemoveDelivery",
+		"SetDelivery",
+		"SetPickupPoint",
+		"ClearCartRequest",
+		"AddVoucher",
+		"RemoveVoucher",
+		"UpsertSubscriptionDetails",
+	}
+
+	names := reg.(*actor.ProtoMutationRegistry).RegisteredMutations()
+	for _, want := range expected {
+		if !slices.Contains(names, want) {
+			t.Fatalf("registry missing mutation %s; got %v", want, names)
+		}
+	}
+
+	// Create() by name returns correct concrete type.
+	for _, name := range expected {
+		msg, ok := reg.Create(name)
+		if !ok {
+			t.Fatalf("Create failed for %s", name)
+		}
+		rt := reflect.TypeOf(msg)
+		if rt.Kind() == reflect.Ptr {
+			rt = rt.Elem()
+		}
+		if rt.Name() != name {
+			t.Fatalf("Create(%s) returned wrong type %s", name, rt.Name())
+		}
+	}
+
+	// Unregistered create
+	if m, ok := reg.Create("DoesNotExist"); ok || m != nil {
+		t.Fatalf("Create should fail for unknown; got (%T,%v)", m, ok)
+	}
+
+	// GetTypeName sanity
+	add := &messages.AddItem{}
+	nm, ok := reg.GetTypeName(add)
+	if !ok || nm != "AddItem" {
+		t.Fatalf("GetTypeName failed for AddItem, got (%q,%v)", nm, ok)
+	}
+
+	// Apply unregistered message -> result should contain ErrMutationNotRegistered, no top-level error
+	results, err := reg.Apply(context.Background(), newTestGrain(), &messages.Noop{})
+	if err != nil {
+		t.Fatalf("unexpected top-level error applying unregistered mutation: %v", err)
+	}
+	if len(results) != 1 || results[0].Error == nil || results[0].Error != actor.ErrMutationNotRegistered {
+		t.Fatalf("expected ApplyResult with ErrMutationNotRegistered, got %#v", results)
+	}
+}
+
+func TestAddItemAndMerging(t *testing.T) {
+	reg := newRegistry()
+	g := newTestGrain()
+
+	// Merge scenario (same SKU + same store pointer)
+	add1 := msgAddItem("SKU-1", 1000, 2, nil)
+	applyOK(t, reg, g, add1)
+
+	if len(g.Items) != 1 || g.Items[0].Quantity != 2 {
+		t.Fatalf("expected first item added; items=%d qty=%d", len(g.Items), g.Items[0].Quantity)
+	}
+
+	applyOK(t, reg, g, msgAddItem("SKU-1", 1000, 3, nil)) // should merge
+	if len(g.Items) != 1 || g.Items[0].Quantity != 5 {
+		t.Fatalf("expected merge quantity=5 items=%d qty=%d", len(g.Items), g.Items[0].Quantity)
+	}
+
+	// Different store pointer -> new line
+	store := "S1"
+	applyOK(t, reg, g, msgAddItem("SKU-1", 1000, 1, &store))
+	if len(g.Items) != 2 {
+		t.Fatalf("expected second line for different store pointer; items=%d", len(g.Items))
+	}
+
+	// Same store pointer & SKU -> merge with second line
+	applyOK(t, reg, g, msgAddItem("SKU-1", 1000, 4, &store))
+	if len(g.Items) != 2 || g.Items[1].Quantity != 5 {
+		t.Fatalf("expected merge on second line; items=%d second.qty=%d", len(g.Items), g.Items[1].Quantity)
+	}
+
+	// Invalid quantity
+	applyErrorContains(t, reg, g, msgAddItem("BAD", 1000, 0, nil), "invalid quantity")
+}
+
+func TestChangeQuantityBehavior(t *testing.T) {
+	reg := newRegistry()
+	g := newTestGrain()
+
+	applyOK(t, reg, g, msgAddItem("A", 1500, 2, nil))
+	id := g.Items[0].Id
+
+	// Increase quantity
+	applyOK(t, reg, g, msgChangeQty(id, 5))
+	if g.Items[0].Quantity != 5 {
+		t.Fatalf("quantity not updated expected=5 got=%d", g.Items[0].Quantity)
+	}
+
+	// Remove item by setting <=0
+	applyOK(t, reg, g, msgChangeQty(id, 0))
+	if len(g.Items) != 0 {
+		t.Fatalf("expected item removed; items=%d", len(g.Items))
+	}
+
+	// Not found
+	applyErrorContains(t, reg, g, msgChangeQty(9999, 1), "not found")
+}
+
+func TestRemoveItemBehavior(t *testing.T) {
+	reg := newRegistry()
+	g := newTestGrain()
+
+	applyOK(t, reg, g, msgAddItem("X", 1200, 1, nil))
+	id := g.Items[0].Id
+
+	applyOK(t, reg, g, msgRemoveItem(id))
+	if len(g.Items) != 0 {
+		t.Fatalf("expected item removed; items=%d", len(g.Items))
+	}
+
+	applyErrorContains(t, reg, g, msgRemoveItem(id), "not found")
+}
+
+func TestDeliveryMutations(t *testing.T) {
+	reg := newRegistry()
+	g := newTestGrain()
+
+	applyOK(t, reg, g, msgAddItem("D1", 1000, 1, nil))
+	applyOK(t, reg, g, msgAddItem("D2", 2000, 1, nil))
+	i1 := g.Items[0].Id
+
+	// Explicit items
+	applyOK(t, reg, g, msgSetDelivery("POSTNORD", i1))
+	if len(g.Deliveries) != 1 || len(g.Deliveries[0].Items) != 1 || g.Deliveries[0].Items[0] != i1 {
+		t.Fatalf("delivery not created as expected: %+v", g.Deliveries)
+	}
+
+	// Attempt to attach an already-delivered item
+	applyErrorContains(t, reg, g, msgSetDelivery("POSTNORD", i1), "already has a delivery")
+
+	// Attach remaining item via empty list (auto include items without delivery)
+	applyOK(t, reg, g, msgSetDelivery("DHL"))
+	if len(g.Deliveries) != 2 {
+		t.Fatalf("expected second delivery; deliveries=%d", len(g.Deliveries))
+	}
+
+	// Non-existent item
+	applyErrorContains(t, reg, g, msgSetDelivery("UPS", 99999), "not found")
+
+	// No eligible items left
+	applyErrorContains(t, reg, g, msgSetDelivery("UPS"), "no eligible items")
+
+	// Set pickup point on first delivery
+	did := g.Deliveries[0].Id
+	applyOK(t, reg, g, msgSetPickupPoint(did, "PP1"))
+	if g.Deliveries[0].PickupPoint == nil || g.Deliveries[0].PickupPoint.Id != "PP1" {
+		t.Fatalf("pickup point not set correctly: %+v", g.Deliveries[0].PickupPoint)
+	}
+
+	// Bad delivery id
+	applyErrorContains(t, reg, g, msgSetPickupPoint(9999, "PPX"), "delivery id")
+
+	// Remove delivery
+	applyOK(t, reg, g, &messages.RemoveDelivery{Id: did})
+	if len(g.Deliveries) != 1 || g.Deliveries[0].Id == did {
+		t.Fatalf("expected first delivery removed, remaining: %+v", g.Deliveries)
+	}
+
+	// Remove delivery not found
+	applyErrorContains(t, reg, g, &messages.RemoveDelivery{Id: did}, "not found")
+}
+
+func TestClearCart(t *testing.T) {
+	reg := newRegistry()
+	g := newTestGrain()
+
+	applyOK(t, reg, g, msgAddItem("X", 1000, 2, nil))
+	applyOK(t, reg, g, msgSetDelivery("P", g.Items[0].Id))
+
+	applyOK(t, reg, g, msgClearCart())
+
+	if len(g.Items) != 0 || len(g.Deliveries) != 0 {
+		t.Fatalf("expected cart cleared; items=%d deliveries=%d", len(g.Items), len(g.Deliveries))
+	}
+}
+
+func TestVoucherMutations(t *testing.T) {
+	reg := newRegistry()
+	g := newTestGrain()
+
+	applyOK(t, reg, g, msgAddItem("VOUCH", 10000, 1, nil))
+	applyOK(t, reg, g, msgAddVoucher("PROMO", 5000))
+
+	if len(g.Vouchers) != 1 {
+		t.Fatalf("voucher not stored")
+	}
+	if g.TotalDiscount.IncVat != 5000 {
+		t.Fatalf("expected discount 5000 got %d", g.TotalDiscount.IncVat)
+	}
+	if g.TotalPrice.IncVat != 5000 {
+		t.Fatalf("expected total price 5000 got %d", g.TotalPrice.IncVat)
+	}
+
+	// Duplicate voucher code
+	applyErrorContains(t, reg, g, msgAddVoucher("PROMO", 1000), "already applied")
+
+	// Add a large voucher (should not apply because value > total price)
+	applyOK(t, reg, g, msgAddVoucher("BIG", 100000))
+	if len(g.Vouchers) != 2 {
+		t.Fatalf("expected second voucher stored")
+	}
+	if g.TotalDiscount.IncVat != 5000 || g.TotalPrice.IncVat != 5000 {
+		t.Fatalf("large voucher incorrectly applied discount=%d total=%d",
+			g.TotalDiscount.IncVat, g.TotalPrice.IncVat)
+	}
+
+	// Remove existing voucher
+	firstId := g.Vouchers[0].Id
+	applyOK(t, reg, g, msgRemoveVoucher(firstId))
+
+	if slices.ContainsFunc(g.Vouchers, func(v *Voucher) bool { return v.Id == firstId }) {
+		t.Fatalf("voucher id %d not removed", firstId)
+	}
+	// After removing PROMO, BIG remains but is not applied (exceeds price)
+	if g.TotalDiscount.IncVat != 0 || g.TotalPrice.IncVat != 10000 {
+		t.Fatalf("totals incorrect after removal discount=%d total=%d",
+			g.TotalDiscount.IncVat, g.TotalPrice.IncVat)
+	}
+
+	// Remove not applied
+	applyErrorContains(t, reg, g, msgRemoveVoucher(firstId), "not applied")
+}
+
+func TestCheckoutMutations(t *testing.T) {
+	reg := newRegistry()
+	g := newTestGrain()
+
+	applyOK(t, reg, g, msgInitializeCheckout("ORD-1", "PENDING", true))
+	if g.OrderReference != "ORD-1" || g.PaymentStatus != "PENDING" || !g.PaymentInProgress {
+		t.Fatalf("initialize checkout failed: ref=%s status=%s inProgress=%v",
+			g.OrderReference, g.PaymentStatus, g.PaymentInProgress)
+	}
+
+	applyOK(t, reg, g, msgOrderCreated("ORD-1", "COMPLETED"))
+	if g.OrderReference != "ORD-1" || g.PaymentStatus != "COMPLETED" || g.PaymentInProgress {
+		t.Fatalf("order created mutation failed: ref=%s status=%s inProgress=%v",
+			g.OrderReference, g.PaymentStatus, g.PaymentInProgress)
+	}
+
+	applyErrorContains(t, reg, g, msgInitializeCheckout("", "X", true), "missing orderId")
+	applyErrorContains(t, reg, g, msgOrderCreated("", "X"), "missing orderId")
+}
+
+func TestSubscriptionDetailsMutation(t *testing.T) {
+	reg := newRegistry()
+	g := newTestGrain()
+
+	// Upsert new (Id == nil)
+	msgNew := &messages.UpsertSubscriptionDetails{
+		OfferingCode: "OFF1",
+		SigningType:  "TYPE1",
+	}
+	applyOK(t, reg, g, msgNew)
+	if len(g.SubscriptionDetails) != 1 {
+		t.Fatalf("expected one subscription detail; got=%d", len(g.SubscriptionDetails))
+	}
+
+	// Capture created id
+	var createdId string
+	for k := range g.SubscriptionDetails {
+		createdId = k
+	}
+
+	// Update existing
+	msgUpdate := &messages.UpsertSubscriptionDetails{
+		Id:           &createdId,
+		OfferingCode: "OFF2",
+		SigningType:  "TYPE2",
+	}
+	applyOK(t, reg, g, msgUpdate)
+	if g.SubscriptionDetails[createdId].OfferingCode != "OFF2" ||
+		g.SubscriptionDetails[createdId].SigningType != "TYPE2" {
+		t.Fatalf("subscription details not updated: %+v", g.SubscriptionDetails[createdId])
+	}
+
+	// Update non-existent
+	badId := "NON_EXISTENT"
+	applyErrorContains(t, reg, g, &messages.UpsertSubscriptionDetails{Id: &badId}, "not found")
+
+	// Nil mutation should be ignored and produce zero results.
+	resultsNil, errNil := reg.Apply(context.Background(), g, (*messages.UpsertSubscriptionDetails)(nil))
+	if errNil != nil {
+		t.Fatalf("unexpected error for nil mutation element: %v", errNil)
+	}
+	if len(resultsNil) != 0 {
+		t.Fatalf("expected zero results for nil mutation, got %d", len(resultsNil))
+	}
+}
+
+// Ensure registry Apply handles nil grain and nil message defensive errors consistently.
+func TestRegistryDefensiveErrors(t *testing.T) {
+	reg := newRegistry()
+	g := newTestGrain()
+
+	// Nil grain
+	results, err := reg.Apply(context.Background(), nil, &messages.AddItem{})
+	if err == nil {
+		t.Fatalf("expected error for nil grain")
+	}
+	if len(results) != 0 {
+		t.Fatalf("expected no results for nil grain")
+	}
+
+	// Nil message slice
+	results, _ = reg.Apply(context.Background(), g, nil)
+
+	if len(results) != 0 {
+		t.Fatalf("expected no results when message slice nil")
+	}
+}
+
+type SubscriptionDetailsRequest struct {
+	Id           *string         `json:"id,omitempty"`
+	OfferingCode string          `json:"offeringCode,omitempty"`
+	SigningType  string          `json:"signingType,omitempty"`
+	Data         json.RawMessage `json:"data,omitempty"`
+}
+
+func (sd *SubscriptionDetailsRequest) ToMessage() *messages.UpsertSubscriptionDetails {
+	return &messages.UpsertSubscriptionDetails{
+		Id:           sd.Id,
+		OfferingCode: sd.OfferingCode,
+		SigningType:  sd.SigningType,
+		Data:         &anypb.Any{Value: sd.Data},
+	}
+}
+
+func TestSubscriptionDetailsJSONValidation(t *testing.T) {
+	reg := newRegistry()
+	g := newTestGrain()
+
+	// Valid JSON on create
+	jsonStr := `{"offeringCode": "OFFJSON", "signingType": "TYPEJSON", "data": {"value":"test","a":1}}`
+	var validCreate SubscriptionDetailsRequest
+	if err := json.Unmarshal([]byte(jsonStr), &validCreate); err != nil {
+		t.Fatal(err)
+	}
+	applyOK(t, reg, g, validCreate.ToMessage())
+	if len(g.SubscriptionDetails) != 1 {
+		t.Fatalf("expected one subscription detail after valid create, got %d", len(g.SubscriptionDetails))
+	}
+	var id string
+	for k := range g.SubscriptionDetails {
+		id = k
+	}
+	if string(g.SubscriptionDetails[id].Meta) != `{"value":"test","a":1}` {
+		t.Fatalf("expected meta stored as valid json, got %s", string(g.SubscriptionDetails[id].Meta))
+	}
+
+	// Update with valid JSON replaces meta
+	jsonStr2 := fmt.Sprintf(`{"id": "%s", "data": {"value": "eyJjaGFuZ2VkIjoxMjN9"}}`, id)
+	var updateValid messages.UpsertSubscriptionDetails
+	if err := json.Unmarshal([]byte(jsonStr2), &updateValid); err != nil {
+		t.Fatal(err)
+	}
+	applyOK(t, reg, g, &updateValid)
+	if string(g.SubscriptionDetails[id].Meta) != `{"changed":123}` {
+		t.Fatalf("expected meta updated to new json, got %s", string(g.SubscriptionDetails[id].Meta))
+	}
+
+	// Invalid JSON on create
+	jsonStr3 := `{"offeringCode": "BAD", "signingType": "TYPE", "data": {"value": "eyJicm9rZW4iO30="}}`
+	var invalidCreate messages.UpsertSubscriptionDetails
+	if err := json.Unmarshal([]byte(jsonStr3), &invalidCreate); err != nil {
+		t.Fatal(err)
+	}
+	res := applyOne(t, reg, g, &invalidCreate)
+	if res.Error == nil || !strings.Contains(res.Error.Error(), "invalid json") {
+		t.Fatalf("expected invalid json error on create, got %v", res.Error)
+	}
+
+	// Invalid JSON on update
+	jsonStr4 := fmt.Sprintf(`{"id": "%s", "data": {"value": "e29vcHM="}}`, id)
+	var badUpdate messages.UpsertSubscriptionDetails
+	if err := json.Unmarshal([]byte(jsonStr4), &badUpdate); err != nil {
+		t.Fatal(err)
+	}
+	res2 := applyOne(t, reg, g, &badUpdate)
+	if res2.Error == nil || !strings.Contains(res2.Error.Error(), "invalid json") {
+		t.Fatalf("expected invalid json error on update, got %v", res2.Error)
+	}
+
+	// Empty Data should not overwrite existing meta
+	jsonStr5 := fmt.Sprintf(`{"id": "%s"}`, id)
+	var emptyUpdate messages.UpsertSubscriptionDetails
+	if err := json.Unmarshal([]byte(jsonStr5), &emptyUpdate); err != nil {
+		t.Fatal(err)
+	}
+	applyOK(t, reg, g, &emptyUpdate)
+	if string(g.SubscriptionDetails[id].Meta) != `{"changed":123}` {
+		t.Fatalf("empty update should not change meta, got %s", string(g.SubscriptionDetails[id].Meta))
+	}
+}

pkg/cart/mutation_upsert_subscriptiondetails.go

@@ -0,0 +1,69 @@
+package cart
+
+import (
+	"encoding/json"
+	"fmt"
+
+	messages "git.tornberg.me/go-cart-actor/pkg/messages"
+)
+
+func UpsertSubscriptionDetails(g *CartGrain, m *messages.UpsertSubscriptionDetails) error {
+	if m == nil {
+		return nil
+	}
+	metaBytes := m.Data.GetValue()
+
+	// Create new subscription details when Id is nil.
+	if m.Id == nil {
+		// Validate JSON if provided.
+		var meta json.RawMessage
+		if metaBytes != nil {
+			if !json.Valid(metaBytes) {
+				return fmt.Errorf("subscription details invalid json")
+			}
+			meta = json.RawMessage(metaBytes)
+		}
+
+		id := MustNewCartId().String()
+
+		g.SubscriptionDetails[id] = &SubscriptionDetails{
+			Id:           id,
+			Version:      1,
+			OfferingCode: m.OfferingCode,
+			SigningType:  m.SigningType,
+			Meta:         meta,
+		}
+		return nil
+	}
+
+	// Update existing entry.
+	existing, ok := g.SubscriptionDetails[*m.Id]
+	if !ok {
+		n := &SubscriptionDetails{
+			Id:      *m.Id,
+			Version: 0,
+		}
+		g.SubscriptionDetails[*m.Id] = n
+		existing = n
+	}
+	changed := false
+	if m.OfferingCode != "" {
+		existing.OfferingCode = m.OfferingCode
+		changed = true
+	}
+	if m.SigningType != "" {
+		existing.SigningType = m.SigningType
+		changed = true
+	}
+	if metaBytes != nil {
+		if !json.Valid(metaBytes) {
+			return fmt.Errorf("subscription details invalid json")
+		}
+		existing.Meta = json.RawMessage(metaBytes)
+		changed = true
+	}
+	if changed {
+		existing.Version++
+	}
+	return nil
+}

pkg/cart/price.go

@@ -0,0 +1,131 @@
+package cart
+
+import (
+	"encoding/json"
+	"strconv"
+)
+
+func GetTaxAmount(total int64, tax int) int64 {
+	taxD := 10000 / float64(tax)
+	return int64(float64(total) / float64((1 + taxD)))
+}
+
+type Price struct {
+	IncVat   int64             `json:"incVat"`
+	VatRates map[float32]int64 `json:"vat,omitempty"`
+}
+
+func NewPrice() *Price {
+	return &Price{
+		IncVat:   0,
+		VatRates: make(map[float32]int64),
+	}
+}
+
+func NewPriceFromIncVat(incVat int64, taxRate float32) *Price {
+	tax := GetTaxAmount(incVat, int(taxRate*100))
+	return &Price{
+		IncVat: incVat,
+		VatRates: map[float32]int64{
+			taxRate: tax,
+		},
+	}
+}
+
+func (p *Price) ValueExVat() int64 {
+	exVat := p.IncVat
+	for _, amount := range p.VatRates {
+		exVat -= amount
+	}
+	return exVat
+}
+
+func (p *Price) TotalVat() int64 {
+	total := int64(0)
+	for _, amount := range p.VatRates {
+		total += amount
+	}
+	return total
+}
+
+func MultiplyPrice(p Price, qty int64) *Price {
+	ret := &Price{
+		IncVat:   p.IncVat * qty,
+		VatRates: make(map[float32]int64),
+	}
+	for rate, amount := range p.VatRates {
+		ret.VatRates[rate] = amount * qty
+	}
+	return ret
+}
+
+func (p *Price) Multiply(qty int64) {
+	p.IncVat *= qty
+	for rate, amount := range p.VatRates {
+		p.VatRates[rate] = amount * qty
+	}
+}
+
+func (p Price) MarshalJSON() ([]byte, error) {
+	// Build a stable wire format without calling Price.MarshalJSON recursively
+	exVat := p.ValueExVat()
+	var vat map[string]int64
+	if len(p.VatRates) > 0 {
+		vat = make(map[string]int64, len(p.VatRates))
+		for rate, amount := range p.VatRates {
+			// Rely on default formatting that trims trailing zeros for whole numbers
+			// Using %g could output scientific notation for large numbers; float32 rates here are small.
+			key := trimFloat(rate)
+			vat[key] = amount
+		}
+	}
+	type wire struct {
+		ExVat  int64            `json:"exVat"`
+		IncVat int64            `json:"incVat"`
+		Vat    map[string]int64 `json:"vat,omitempty"`
+	}
+	return json.Marshal(wire{ExVat: exVat, IncVat: p.IncVat, Vat: vat})
+}
+
+// trimFloat converts a float32 tax rate like 25 or 12.5 into a compact string without
+// unnecessary decimals ("25", "12.5").
+func trimFloat(f float32) string {
+	// Convert via FormatFloat then trim trailing zeros and dot.
+	s := strconv.FormatFloat(float64(f), 'f', -1, 32)
+	return s
+}
+
+func (p *Price) Add(price Price) {
+	p.IncVat += price.IncVat
+	for rate, amount := range price.VatRates {
+		p.VatRates[rate] += amount
+	}
+}
+
+func (p *Price) Subtract(price Price) {
+	p.IncVat -= price.IncVat
+	for rate, amount := range price.VatRates {
+		p.VatRates[rate] -= amount
+	}
+}
+
+func SumPrices(prices ...Price) *Price {
+	if len(prices) == 0 {
+		return NewPrice()
+	}
+
+	aggregated := NewPrice()
+
+	for _, price := range prices {
+		aggregated.IncVat += price.IncVat
+		for rate, amount := range price.VatRates {
+			aggregated.VatRates[rate] += amount
+		}
+	}
+
+	if len(aggregated.VatRates) == 0 {
+		aggregated.VatRates = nil
+	}
+
+	return aggregated
+}

pkg/cart/price_test.go

@@ -0,0 +1,238 @@
+package cart
+
+import (
+	"encoding/json"
+	"testing"
+)
+
+func TestPriceMarshalJSON(t *testing.T) {
+	p := Price{IncVat: 13700, VatRates: map[float32]int64{25: 2500, 12: 1200}}
+	// ExVat = 13700 - (2500+1200) = 10000
+	data, err := json.Marshal(p)
+	if err != nil {
+		t.Fatalf("marshal error: %v", err)
+	}
+	// Unmarshal into a generic struct to validate fields
+	var out struct {
+		ExVat  int64            `json:"exVat"`
+		IncVat int64            `json:"incVat"`
+		Vat    map[string]int64 `json:"vat"`
+	}
+	if err := json.Unmarshal(data, &out); err != nil {
+		t.Fatalf("unmarshal error: %v", err)
+	}
+	if out.ExVat != 10000 {
+		t.Fatalf("expected exVat 10000 got %d", out.ExVat)
+	}
+	if out.IncVat != 13700 {
+		t.Fatalf("expected incVat 13700 got %d", out.IncVat)
+	}
+	if out.Vat["25"] != 2500 || out.Vat["12"] != 1200 {
+		t.Fatalf("unexpected vat map: %#v", out.Vat)
+	}
+}
+
+func TestNewPriceFromIncVat(t *testing.T) {
+	p := NewPriceFromIncVat(1250, 25)
+	if p.IncVat != 1250 {
+		t.Fatalf("expected IncVat %d got %d", 1250, p.IncVat)
+	}
+	if p.VatRates[25] != 250 {
+		t.Fatalf("expected VAT 25 rate %d got %d", 250, p.VatRates[25])
+	}
+	if p.ValueExVat() != 1000 {
+		t.Fatalf("expected exVat %d got %d", 750, p.ValueExVat())
+	}
+}
+
+func TestSumPrices(t *testing.T) {
+	// We'll construct prices via raw struct since constructor expects tax math.
+	// IncVat already includes vat portions.
+	a := Price{IncVat: 1250, VatRates: map[float32]int64{25: 250}}          // ex=1000
+	b := Price{IncVat: 2740, VatRates: map[float32]int64{25: 500, 12: 240}} // ex=2000
+	c := Price{IncVat: 0, VatRates: nil}
+
+	sum := SumPrices(a, b, c)
+
+	if sum.IncVat != 3990 { // 1250+2740
+		t.Fatalf("expected incVat 3990 got %d", sum.IncVat)
+	}
+	if len(sum.VatRates) != 2 {
+		t.Fatalf("expected 2 vat rates got %d", len(sum.VatRates))
+	}
+	if sum.VatRates[25] != 750 {
+		t.Fatalf("expected 25%% vat 750 got %d", sum.VatRates[25])
+	}
+	if sum.VatRates[12] != 240 {
+		t.Fatalf("expected 12%% vat 240 got %d", sum.VatRates[12])
+	}
+	if sum.ValueExVat() != 3000 { // 3990 - (750+240)
+		t.Fatalf("expected exVat 3000 got %d", sum.ValueExVat())
+	}
+}
+
+func TestSumPricesEmpty(t *testing.T) {
+	sum := SumPrices()
+	if sum.IncVat != 0 || sum.VatRates == nil { // constructor sets empty map
+		t.Fatalf("expected zero price got %#v", sum)
+	}
+}
+
+func TestMultiplyPriceFunction(t *testing.T) {
+	base := Price{IncVat: 1250, VatRates: map[float32]int64{25: 250}}
+	multiplied := MultiplyPrice(base, 3)
+	if multiplied.IncVat != 1250*3 {
+		t.Fatalf("expected IncVat %d got %d", 1250*3, multiplied.IncVat)
+	}
+	if multiplied.VatRates[25] != 250*3 {
+		t.Fatalf("expected VAT 25 rate %d got %d", 250*3, multiplied.VatRates[25])
+	}
+	if multiplied.ValueExVat() != (1250-250)*3 {
+		t.Fatalf("expected exVat %d got %d", (1250-250)*3, multiplied.ValueExVat())
+	}
+}
+
+func TestPriceAddSubtract(t *testing.T) {
+	a := Price{IncVat: 1000, VatRates: map[float32]int64{25: 200}}
+	b := Price{IncVat: 500, VatRates: map[float32]int64{25: 100, 12: 54}}
+
+	acc := NewPrice()
+	acc.Add(a)
+	acc.Add(b)
+
+	if acc.IncVat != 1500 {
+		t.Fatalf("expected IncVat 1500 got %d", acc.IncVat)
+	}
+	if acc.VatRates[25] != 300 || acc.VatRates[12] != 54 {
+		t.Fatalf("unexpected VAT map: %#v", acc.VatRates)
+	}
+
+	// Subtract b then a returns to zero
+	acc.Subtract(b)
+	acc.Subtract(a)
+	if acc.IncVat != 0 {
+		t.Fatalf("expected IncVat 0 got %d", acc.IncVat)
+	}
+	if len(acc.VatRates) != 2 || acc.VatRates[25] != 0 || acc.VatRates[12] != 0 {
+		t.Fatalf("expected zeroed vat rates got %#v", acc.VatRates)
+	}
+}
+
+func TestPriceMultiplyMethod(t *testing.T) {
+	p := Price{IncVat: 2000, VatRates: map[float32]int64{25: 400}}
+	// Value before multiply
+	exBefore := p.ValueExVat()
+	p.Multiply(2)
+	if p.IncVat != 4000 {
+		t.Fatalf("expected IncVat 4000 got %d", p.IncVat)
+	}
+	if p.VatRates[25] != 800 {
+		t.Fatalf("expected VAT 800 got %d", p.VatRates[25])
+	}
+	if p.ValueExVat() != exBefore*2 {
+		t.Fatalf("expected exVat %d got %d", exBefore*2, p.ValueExVat())
+	}
+}
+
+func TestGetTaxAmount(t *testing.T) {
+	tests := []struct {
+		total    int64
+		tax      int
+		expected int64
+		desc     string
+	}{
+		{1250, 2500, 250, "25% VAT"}, // 1250 / (1 + 100/25) = 1250 / 5 = 250
+		{1000, 2000, 166, "20% VAT"}, // 1000 / (1 + 100/20) = 1000 / 6 ≈ 166
+		{1200, 2500, 240, "25% VAT on 1200"},
+		{0, 2500, 0, "zero total"},
+		{100, 1000, 9, "10% VAT"},    // tax=1000 for 10%, 100 / (1 + 100/10) = 100 / 11 ≈ 9
+		{100, 10000, 50, "100% VAT"}, // tax=10000 for 100%, 100 / (1 + 100/100) = 100 / 2 = 50
+	}
+
+	for _, tt := range tests {
+		result := GetTaxAmount(tt.total, tt.tax)
+		if result != tt.expected {
+			t.Errorf("GetTaxAmount(%d, %d) [%s] = %d; expected %d", tt.total, tt.tax, tt.desc, result, tt.expected)
+		}
+	}
+}
+
+func TestNewPriceFromIncVatEdgeCases(t *testing.T) {
+	// Zero VAT rate
+	p := NewPriceFromIncVat(1000, 0)
+	if p.IncVat != 1000 {
+		t.Errorf("expected IncVat 1000, got %d", p.IncVat)
+	}
+	if len(p.VatRates) != 1 || p.VatRates[0] != 0 {
+		t.Errorf("expected VAT 0 for rate 0, got %v", p.VatRates)
+	}
+	if p.ValueExVat() != 1000 {
+		t.Errorf("expected exVat 1000, got %d", p.ValueExVat())
+	}
+
+	// High VAT rate, e.g., 50%
+	p = NewPriceFromIncVat(1500, 50)
+	expectedVat := int64(1500 / (1 + 100/50)) // 1500 / 3 = 500
+	if p.VatRates[50] != expectedVat {
+		t.Errorf("expected VAT %d for 50%%, got %d", expectedVat, p.VatRates[50])
+	}
+	if p.ValueExVat() != 1500-expectedVat {
+		t.Errorf("expected exVat %d, got %d", 1500-expectedVat, p.ValueExVat())
+	}
+}
+
+func TestPriceValueExVatAndTotalVat(t *testing.T) {
+	p := Price{IncVat: 13700, VatRates: map[float32]int64{25: 2500, 12: 1200}}
+	exVat := p.ValueExVat()
+	totalVat := p.TotalVat()
+	if exVat != 10000 {
+		t.Errorf("expected exVat 10000, got %d", exVat)
+	}
+	if totalVat != 3700 {
+		t.Errorf("expected totalVat 3700, got %d", totalVat)
+	}
+	if exVat+totalVat != p.IncVat {
+		t.Errorf("exVat + totalVat should equal IncVat: %d + %d != %d", exVat, totalVat, p.IncVat)
+	}
+
+	// Empty VAT rates
+	p2 := Price{IncVat: 500, VatRates: nil}
+	if p2.ValueExVat() != 500 {
+		t.Errorf("expected exVat 500 for no VAT, got %d", p2.ValueExVat())
+	}
+	if p2.TotalVat() != 0 {
+		t.Errorf("expected totalVat 0, got %d", p2.TotalVat())
+	}
+}
+
+func TestMultiplyPriceWithZeroQty(t *testing.T) {
+	base := Price{IncVat: 1250, VatRates: map[float32]int64{25: 250}}
+	multiplied := MultiplyPrice(base, 0)
+	if multiplied.IncVat != 0 {
+		t.Errorf("expected IncVat 0, got %d", multiplied.IncVat)
+	}
+	if len(multiplied.VatRates) != 1 || multiplied.VatRates[25] != 0 {
+		t.Errorf("expected VAT 0, got %v", multiplied.VatRates)
+	}
+}
+
+func TestPriceAddSubtractEdgeCases(t *testing.T) {
+	a := Price{IncVat: 1000, VatRates: map[float32]int64{25: 200}}
+	b := Price{IncVat: 500, VatRates: map[float32]int64{12: 54}} // Different rate
+
+	acc := NewPrice()
+	acc.Add(a)
+	acc.Add(b)
+
+	if acc.VatRates[25] != 200 || acc.VatRates[12] != 54 {
+		t.Errorf("expected VAT 25:200, 12:54, got %v", acc.VatRates)
+	}
+
+	// Subtract more than added (negative VAT)
+	acc.Subtract(a)
+	acc.Subtract(b)
+	acc.Subtract(a) // Subtract extra a
+	if acc.VatRates[25] != -200 || acc.VatRates[12] != 0 {
+		t.Errorf("expected negative VAT for 25 after over-subtract, got %v", acc.VatRates)
+	}
+}

pkg/discovery/discovery.go

@@ -1,7 +1,9 @@
-package main
+package discovery
 
 import (
 	"context"
+	"slices"
+	"sync"
 
 	v1 "k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
@@ -11,11 +13,6 @@ import (
 	toolsWatch "k8s.io/client-go/tools/watch"
 )
 
-type Discovery interface {
-	Discover() ([]string, error)
-	Watch() (<-chan HostChange, error)
-}
-
 type K8sDiscovery struct {
 	ctx    context.Context
 	client *kubernetes.Clientset
@@ -38,20 +35,17 @@ func (k *K8sDiscovery) DiscoverInNamespace(namespace string) ([]string, error) {
 	return hosts, nil
 }
 
-type HostChange struct {
-	Host string
-	Type watch.EventType
-}
-
 func (k *K8sDiscovery) Watch() (<-chan HostChange, error) {
 	timeout := int64(30)
+	ipsThatAreReady := make(map[string]bool)
+	m := sync.Mutex{}
 	watcherFn := func(options metav1.ListOptions) (watch.Interface, error) {
 		return k.client.CoreV1().Pods("").Watch(k.ctx, metav1.ListOptions{
 			LabelSelector:  "actor-pool=cart",
 			TimeoutSeconds: &timeout,
 		})
 	}
-	watcher, err := toolsWatch.NewRetryWatcher("1", &cache.ListWatch{WatchFunc: watcherFn})
+	watcher, err := toolsWatch.NewRetryWatcherWithContext(k.ctx, "1", &cache.ListWatch{WatchFunc: watcherFn})
 	if err != nil {
 		return nil, err
 	}
@@ -60,9 +54,22 @@ func (k *K8sDiscovery) Watch() (<-chan HostChange, error) {
 		for event := range watcher.ResultChan() {
 
 			pod := event.Object.(*v1.Pod)
+			isReady := slices.ContainsFunc(pod.Status.Conditions, func(condition v1.PodCondition) bool {
+				return condition.Type == v1.PodReady && condition.Status == v1.ConditionTrue
+			})
+			m.Lock()
+			oldState := ipsThatAreReady[pod.Status.PodIP]
+			ipsThatAreReady[pod.Status.PodIP] = isReady
+			m.Unlock()
+			if oldState != isReady {
+				ch <- HostChange{
+					Host:    pod.Status.PodIP,
+					IsReady: isReady,
+				}
+			}
 			ch <- HostChange{
-				Host: pod.Status.PodIP,
+				Host:    pod.Status.PodIP,
-				Type: event.Type,
+				IsReady: isReady,
 			}
 		}
 	}()

pkg/discovery/discovery_mock.go

@@ -0,0 +1,99 @@
+package discovery
+
+import (
+	"context"
+	"slices"
+	"sync"
+)
+
+// MockDiscovery is an in-memory Discovery implementation for tests.
+// It allows deterministic injection of host additions/removals without
+// depending on Kubernetes API machinery.
+type MockDiscovery struct {
+	mu      sync.RWMutex
+	hosts   []string
+	events  chan HostChange
+	closed  bool
+	started bool
+}
+
+// NewMockDiscovery creates a mock discovery with an initial host list.
+func NewMockDiscovery(initial []string) *MockDiscovery {
+	cp := make([]string, len(initial))
+	copy(cp, initial)
+	return &MockDiscovery{
+		hosts:  cp,
+		events: make(chan HostChange, 32),
+	}
+}
+
+// Discover returns the current host snapshot.
+func (m *MockDiscovery) Discover() ([]string, error) {
+	m.mu.RLock()
+	defer m.mu.RUnlock()
+	cp := make([]string, len(m.hosts))
+	copy(cp, m.hosts)
+	return cp, nil
+}
+
+// Watch returns a channel that will receive HostChange events.
+// The channel is buffered; AddHost/RemoveHost push events non-blockingly.
+func (m *MockDiscovery) Watch() (<-chan HostChange, error) {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	if m.closed {
+		return nil, context.Canceled
+	}
+	m.started = true
+	return m.events, nil
+}
+
+// AddHost inserts a new host (if absent) and emits an Added event.
+func (m *MockDiscovery) AddHost(host string) {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	if m.closed {
+		return
+	}
+	if slices.Contains(m.hosts, host) {
+		return
+	}
+	m.hosts = append(m.hosts, host)
+	if m.started {
+		m.events <- HostChange{Host: host, IsReady: true}
+	}
+}
+
+// RemoveHost removes a host (if present) and emits a Deleted event.
+func (m *MockDiscovery) RemoveHost(host string) {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	if m.closed {
+		return
+	}
+	idx := -1
+	for i, h := range m.hosts {
+		if h == host {
+			idx = i
+			break
+		}
+	}
+	if idx == -1 {
+		return
+	}
+	m.hosts = append(m.hosts[:idx], m.hosts[idx+1:]...)
+	if m.started {
+		m.events <- HostChange{Host: host, IsReady: false}
+	}
+}
+
+// Close closes the event channel (idempotent).
+func (m *MockDiscovery) Close() {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	if m.closed {
+		return
+	}
+	m.closed = true
+	close(m.events)
+}

pkg/discovery/discovery_test.go

@@ -1,4 +1,4 @@
-package main
+package discovery
 
 import (
 	"testing"
@@ -9,7 +9,7 @@ import (
 )
 
 func TestDiscovery(t *testing.T) {
-	config, err := clientcmd.BuildConfigFromFlags("", "/Users/mats/.kube/config")
+	config, err := clientcmd.BuildConfigFromFlags("", "/home/mats/.kube/config")
 	if err != nil {
 		t.Errorf("Error building config: %v", err)
 	}
@@ -28,7 +28,7 @@ func TestDiscovery(t *testing.T) {
 }
 
 func TestWatch(t *testing.T) {
-	config, err := clientcmd.BuildConfigFromFlags("", "/Users/mats/.kube/config")
+	config, err := clientcmd.BuildConfigFromFlags("", "/home/mats/.kube/config")
 	if err != nil {
 		t.Errorf("Error building config: %v", err)
 	}

pkg/discovery/types.go

@@ -0,0 +1,11 @@
+package discovery
+
+type HostChange struct {
+	Host    string
+	IsReady bool
+}
+
+type Discovery interface {
+	Discover() ([]string, error)
+	Watch() (<-chan HostChange, error)
+}

pkg/messages/control_plane.pb.go

@@ -0,0 +1,582 @@
+// Code generated by protoc-gen-go. DO NOT EDIT.
+// versions:
+// 	protoc-gen-go v1.36.5
+// 	protoc        v6.33.1
+// source: control_plane.proto
+
+package messages
+
+import (
+	protoreflect "google.golang.org/protobuf/reflect/protoreflect"
+	protoimpl "google.golang.org/protobuf/runtime/protoimpl"
+	reflect "reflect"
+	sync "sync"
+	unsafe "unsafe"
+)
+
+const (
+	// Verify that this generated code is sufficiently up-to-date.
+	_ = protoimpl.EnforceVersion(20 - protoimpl.MinVersion)
+	// Verify that runtime/protoimpl is sufficiently up-to-date.
+	_ = protoimpl.EnforceVersion(protoimpl.MaxVersion - 20)
+)
+
+// Empty request placeholder (common pattern).
+type Empty struct {
+	state         protoimpl.MessageState `protogen:"open.v1"`
+	unknownFields protoimpl.UnknownFields
+	sizeCache     protoimpl.SizeCache
+}
+
+func (x *Empty) Reset() {
+	*x = Empty{}
+	mi := &file_control_plane_proto_msgTypes[0]
+	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+	ms.StoreMessageInfo(mi)
+}
+
+func (x *Empty) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*Empty) ProtoMessage() {}
+
+func (x *Empty) ProtoReflect() protoreflect.Message {
+	mi := &file_control_plane_proto_msgTypes[0]
+	if x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use Empty.ProtoReflect.Descriptor instead.
+func (*Empty) Descriptor() ([]byte, []int) {
+	return file_control_plane_proto_rawDescGZIP(), []int{0}
+}
+
+// Ping reply includes responding host and its current unix time (seconds).
+type PingReply struct {
+	state         protoimpl.MessageState `protogen:"open.v1"`
+	Host          string                 `protobuf:"bytes,1,opt,name=host,proto3" json:"host,omitempty"`
+	UnixTime      int64                  `protobuf:"varint,2,opt,name=unix_time,json=unixTime,proto3" json:"unix_time,omitempty"`
+	unknownFields protoimpl.UnknownFields
+	sizeCache     protoimpl.SizeCache
+}
+
+func (x *PingReply) Reset() {
+	*x = PingReply{}
+	mi := &file_control_plane_proto_msgTypes[1]
+	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+	ms.StoreMessageInfo(mi)
+}
+
+func (x *PingReply) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*PingReply) ProtoMessage() {}
+
+func (x *PingReply) ProtoReflect() protoreflect.Message {
+	mi := &file_control_plane_proto_msgTypes[1]
+	if x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use PingReply.ProtoReflect.Descriptor instead.
+func (*PingReply) Descriptor() ([]byte, []int) {
+	return file_control_plane_proto_rawDescGZIP(), []int{1}
+}
+
+func (x *PingReply) GetHost() string {
+	if x != nil {
+		return x.Host
+	}
+	return ""
+}
+
+func (x *PingReply) GetUnixTime() int64 {
+	if x != nil {
+		return x.UnixTime
+	}
+	return 0
+}
+
+// NegotiateRequest carries the caller's full view of known hosts (including self).
+type NegotiateRequest struct {
+	state         protoimpl.MessageState `protogen:"open.v1"`
+	KnownHosts    []string               `protobuf:"bytes,1,rep,name=known_hosts,json=knownHosts,proto3" json:"known_hosts,omitempty"`
+	unknownFields protoimpl.UnknownFields
+	sizeCache     protoimpl.SizeCache
+}
+
+func (x *NegotiateRequest) Reset() {
+	*x = NegotiateRequest{}
+	mi := &file_control_plane_proto_msgTypes[2]
+	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+	ms.StoreMessageInfo(mi)
+}
+
+func (x *NegotiateRequest) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*NegotiateRequest) ProtoMessage() {}
+
+func (x *NegotiateRequest) ProtoReflect() protoreflect.Message {
+	mi := &file_control_plane_proto_msgTypes[2]
+	if x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use NegotiateRequest.ProtoReflect.Descriptor instead.
+func (*NegotiateRequest) Descriptor() ([]byte, []int) {
+	return file_control_plane_proto_rawDescGZIP(), []int{2}
+}
+
+func (x *NegotiateRequest) GetKnownHosts() []string {
+	if x != nil {
+		return x.KnownHosts
+	}
+	return nil
+}
+
+// NegotiateReply returns the callee's healthy hosts (including itself).
+type NegotiateReply struct {
+	state         protoimpl.MessageState `protogen:"open.v1"`
+	Hosts         []string               `protobuf:"bytes,1,rep,name=hosts,proto3" json:"hosts,omitempty"`
+	unknownFields protoimpl.UnknownFields
+	sizeCache     protoimpl.SizeCache
+}
+
+func (x *NegotiateReply) Reset() {
+	*x = NegotiateReply{}
+	mi := &file_control_plane_proto_msgTypes[3]
+	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+	ms.StoreMessageInfo(mi)
+}
+
+func (x *NegotiateReply) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*NegotiateReply) ProtoMessage() {}
+
+func (x *NegotiateReply) ProtoReflect() protoreflect.Message {
+	mi := &file_control_plane_proto_msgTypes[3]
+	if x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use NegotiateReply.ProtoReflect.Descriptor instead.
+func (*NegotiateReply) Descriptor() ([]byte, []int) {
+	return file_control_plane_proto_rawDescGZIP(), []int{3}
+}
+
+func (x *NegotiateReply) GetHosts() []string {
+	if x != nil {
+		return x.Hosts
+	}
+	return nil
+}
+
+// CartIdsReply returns the list of cart IDs (string form) currently owned locally.
+type ActorIdsReply struct {
+	state         protoimpl.MessageState `protogen:"open.v1"`
+	Ids           []uint64               `protobuf:"varint,1,rep,packed,name=ids,proto3" json:"ids,omitempty"`
+	unknownFields protoimpl.UnknownFields
+	sizeCache     protoimpl.SizeCache
+}
+
+func (x *ActorIdsReply) Reset() {
+	*x = ActorIdsReply{}
+	mi := &file_control_plane_proto_msgTypes[4]
+	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+	ms.StoreMessageInfo(mi)
+}
+
+func (x *ActorIdsReply) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*ActorIdsReply) ProtoMessage() {}
+
+func (x *ActorIdsReply) ProtoReflect() protoreflect.Message {
+	mi := &file_control_plane_proto_msgTypes[4]
+	if x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use ActorIdsReply.ProtoReflect.Descriptor instead.
+func (*ActorIdsReply) Descriptor() ([]byte, []int) {
+	return file_control_plane_proto_rawDescGZIP(), []int{4}
+}
+
+func (x *ActorIdsReply) GetIds() []uint64 {
+	if x != nil {
+		return x.Ids
+	}
+	return nil
+}
+
+// OwnerChangeAck retained as response type for Closing RPC (ConfirmOwner removed).
+type OwnerChangeAck struct {
+	state         protoimpl.MessageState `protogen:"open.v1"`
+	Accepted      bool                   `protobuf:"varint,1,opt,name=accepted,proto3" json:"accepted,omitempty"`
+	Message       string                 `protobuf:"bytes,2,opt,name=message,proto3" json:"message,omitempty"`
+	unknownFields protoimpl.UnknownFields
+	sizeCache     protoimpl.SizeCache
+}
+
+func (x *OwnerChangeAck) Reset() {
+	*x = OwnerChangeAck{}
+	mi := &file_control_plane_proto_msgTypes[5]
+	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+	ms.StoreMessageInfo(mi)
+}
+
+func (x *OwnerChangeAck) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*OwnerChangeAck) ProtoMessage() {}
+
+func (x *OwnerChangeAck) ProtoReflect() protoreflect.Message {
+	mi := &file_control_plane_proto_msgTypes[5]
+	if x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use OwnerChangeAck.ProtoReflect.Descriptor instead.
+func (*OwnerChangeAck) Descriptor() ([]byte, []int) {
+	return file_control_plane_proto_rawDescGZIP(), []int{5}
+}
+
+func (x *OwnerChangeAck) GetAccepted() bool {
+	if x != nil {
+		return x.Accepted
+	}
+	return false
+}
+
+func (x *OwnerChangeAck) GetMessage() string {
+	if x != nil {
+		return x.Message
+	}
+	return ""
+}
+
+// ClosingNotice notifies peers this host is terminating (so they can drop / re-resolve).
+type ClosingNotice struct {
+	state         protoimpl.MessageState `protogen:"open.v1"`
+	Host          string                 `protobuf:"bytes,1,opt,name=host,proto3" json:"host,omitempty"`
+	unknownFields protoimpl.UnknownFields
+	sizeCache     protoimpl.SizeCache
+}
+
+func (x *ClosingNotice) Reset() {
+	*x = ClosingNotice{}
+	mi := &file_control_plane_proto_msgTypes[6]
+	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+	ms.StoreMessageInfo(mi)
+}
+
+func (x *ClosingNotice) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*ClosingNotice) ProtoMessage() {}
+
+func (x *ClosingNotice) ProtoReflect() protoreflect.Message {
+	mi := &file_control_plane_proto_msgTypes[6]
+	if x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use ClosingNotice.ProtoReflect.Descriptor instead.
+func (*ClosingNotice) Descriptor() ([]byte, []int) {
+	return file_control_plane_proto_rawDescGZIP(), []int{6}
+}
+
+func (x *ClosingNotice) GetHost() string {
+	if x != nil {
+		return x.Host
+	}
+	return ""
+}
+
+// OwnershipAnnounce broadcasts first-touch ownership claims for cart IDs.
+// First claim wins; receivers SHOULD NOT overwrite an existing different owner.
+type OwnershipAnnounce struct {
+	state         protoimpl.MessageState `protogen:"open.v1"`
+	Host          string                 `protobuf:"bytes,1,opt,name=host,proto3" json:"host,omitempty"`       // announcing host
+	Ids           []uint64               `protobuf:"varint,2,rep,packed,name=ids,proto3" json:"ids,omitempty"` // newly claimed cart ids
+	unknownFields protoimpl.UnknownFields
+	sizeCache     protoimpl.SizeCache
+}
+
+func (x *OwnershipAnnounce) Reset() {
+	*x = OwnershipAnnounce{}
+	mi := &file_control_plane_proto_msgTypes[7]
+	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+	ms.StoreMessageInfo(mi)
+}
+
+func (x *OwnershipAnnounce) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*OwnershipAnnounce) ProtoMessage() {}
+
+func (x *OwnershipAnnounce) ProtoReflect() protoreflect.Message {
+	mi := &file_control_plane_proto_msgTypes[7]
+	if x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use OwnershipAnnounce.ProtoReflect.Descriptor instead.
+func (*OwnershipAnnounce) Descriptor() ([]byte, []int) {
+	return file_control_plane_proto_rawDescGZIP(), []int{7}
+}
+
+func (x *OwnershipAnnounce) GetHost() string {
+	if x != nil {
+		return x.Host
+	}
+	return ""
+}
+
+func (x *OwnershipAnnounce) GetIds() []uint64 {
+	if x != nil {
+		return x.Ids
+	}
+	return nil
+}
+
+// ExpiryAnnounce broadcasts that a host evicted the provided cart IDs.
+type ExpiryAnnounce struct {
+	state         protoimpl.MessageState `protogen:"open.v1"`
+	Host          string                 `protobuf:"bytes,1,opt,name=host,proto3" json:"host,omitempty"`
+	Ids           []uint64               `protobuf:"varint,2,rep,packed,name=ids,proto3" json:"ids,omitempty"`
+	unknownFields protoimpl.UnknownFields
+	sizeCache     protoimpl.SizeCache
+}
+
+func (x *ExpiryAnnounce) Reset() {
+	*x = ExpiryAnnounce{}
+	mi := &file_control_plane_proto_msgTypes[8]
+	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+	ms.StoreMessageInfo(mi)
+}
+
+func (x *ExpiryAnnounce) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*ExpiryAnnounce) ProtoMessage() {}
+
+func (x *ExpiryAnnounce) ProtoReflect() protoreflect.Message {
+	mi := &file_control_plane_proto_msgTypes[8]
+	if x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use ExpiryAnnounce.ProtoReflect.Descriptor instead.
+func (*ExpiryAnnounce) Descriptor() ([]byte, []int) {
+	return file_control_plane_proto_rawDescGZIP(), []int{8}
+}
+
+func (x *ExpiryAnnounce) GetHost() string {
+	if x != nil {
+		return x.Host
+	}
+	return ""
+}
+
+func (x *ExpiryAnnounce) GetIds() []uint64 {
+	if x != nil {
+		return x.Ids
+	}
+	return nil
+}
+
+var File_control_plane_proto protoreflect.FileDescriptor
+
+var file_control_plane_proto_rawDesc = string([]byte{
+	0x0a, 0x13, 0x63, 0x6f, 0x6e, 0x74, 0x72, 0x6f, 0x6c, 0x5f, 0x70, 0x6c, 0x61, 0x6e, 0x65, 0x2e,
+	0x70, 0x72, 0x6f, 0x74, 0x6f, 0x12, 0x08, 0x6d, 0x65, 0x73, 0x73, 0x61, 0x67, 0x65, 0x73, 0x22,
+	0x07, 0x0a, 0x05, 0x45, 0x6d, 0x70, 0x74, 0x79, 0x22, 0x3c, 0x0a, 0x09, 0x50, 0x69, 0x6e, 0x67,
+	0x52, 0x65, 0x70, 0x6c, 0x79, 0x12, 0x12, 0x0a, 0x04, 0x68, 0x6f, 0x73, 0x74, 0x18, 0x01, 0x20,
+	0x01, 0x28, 0x09, 0x52, 0x04, 0x68, 0x6f, 0x73, 0x74, 0x12, 0x1b, 0x0a, 0x09, 0x75, 0x6e, 0x69,
+	0x78, 0x5f, 0x74, 0x69, 0x6d, 0x65, 0x18, 0x02, 0x20, 0x01, 0x28, 0x03, 0x52, 0x08, 0x75, 0x6e,
+	0x69, 0x78, 0x54, 0x69, 0x6d, 0x65, 0x22, 0x33, 0x0a, 0x10, 0x4e, 0x65, 0x67, 0x6f, 0x74, 0x69,
+	0x61, 0x74, 0x65, 0x52, 0x65, 0x71, 0x75, 0x65, 0x73, 0x74, 0x12, 0x1f, 0x0a, 0x0b, 0x6b, 0x6e,
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+	0x74, 0x2d, 0x61, 0x63, 0x74, 0x6f, 0x72, 0x2f, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x3b, 0x6d, 0x65,
+	0x73, 0x73, 0x61, 0x67, 0x65, 0x73, 0x62, 0x06, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x33,
+})
+
+var (
+	file_control_plane_proto_rawDescOnce sync.Once
+	file_control_plane_proto_rawDescData []byte
+)
+
+func file_control_plane_proto_rawDescGZIP() []byte {
+	file_control_plane_proto_rawDescOnce.Do(func() {
+		file_control_plane_proto_rawDescData = protoimpl.X.CompressGZIP(unsafe.Slice(unsafe.StringData(file_control_plane_proto_rawDesc), len(file_control_plane_proto_rawDesc)))
+	})
+	return file_control_plane_proto_rawDescData
+}
+
+var file_control_plane_proto_msgTypes = make([]protoimpl.MessageInfo, 9)
+var file_control_plane_proto_goTypes = []any{
+	(*Empty)(nil),             // 0: messages.Empty
+	(*PingReply)(nil),         // 1: messages.PingReply
+	(*NegotiateRequest)(nil),  // 2: messages.NegotiateRequest
+	(*NegotiateReply)(nil),    // 3: messages.NegotiateReply
+	(*ActorIdsReply)(nil),     // 4: messages.ActorIdsReply
+	(*OwnerChangeAck)(nil),    // 5: messages.OwnerChangeAck
+	(*ClosingNotice)(nil),     // 6: messages.ClosingNotice
+	(*OwnershipAnnounce)(nil), // 7: messages.OwnershipAnnounce
+	(*ExpiryAnnounce)(nil),    // 8: messages.ExpiryAnnounce
+}
+var file_control_plane_proto_depIdxs = []int32{
+	0, // 0: messages.ControlPlane.Ping:input_type -> messages.Empty
+	2, // 1: messages.ControlPlane.Negotiate:input_type -> messages.NegotiateRequest
+	0, // 2: messages.ControlPlane.GetLocalActorIds:input_type -> messages.Empty
+	7, // 3: messages.ControlPlane.AnnounceOwnership:input_type -> messages.OwnershipAnnounce
+	8, // 4: messages.ControlPlane.AnnounceExpiry:input_type -> messages.ExpiryAnnounce
+	6, // 5: messages.ControlPlane.Closing:input_type -> messages.ClosingNotice
+	1, // 6: messages.ControlPlane.Ping:output_type -> messages.PingReply
+	3, // 7: messages.ControlPlane.Negotiate:output_type -> messages.NegotiateReply
+	4, // 8: messages.ControlPlane.GetLocalActorIds:output_type -> messages.ActorIdsReply
+	5, // 9: messages.ControlPlane.AnnounceOwnership:output_type -> messages.OwnerChangeAck
+	5, // 10: messages.ControlPlane.AnnounceExpiry:output_type -> messages.OwnerChangeAck
+	5, // 11: messages.ControlPlane.Closing:output_type -> messages.OwnerChangeAck
+	6, // [6:12] is the sub-list for method output_type
+	0, // [0:6] is the sub-list for method input_type
+	0, // [0:0] is the sub-list for extension type_name
+	0, // [0:0] is the sub-list for extension extendee
+	0, // [0:0] is the sub-list for field type_name
+}
+
+func init() { file_control_plane_proto_init() }
+func file_control_plane_proto_init() {
+	if File_control_plane_proto != nil {
+		return
+	}
+	type x struct{}
+	out := protoimpl.TypeBuilder{
+		File: protoimpl.DescBuilder{
+			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
+			RawDescriptor: unsafe.Slice(unsafe.StringData(file_control_plane_proto_rawDesc), len(file_control_plane_proto_rawDesc)),
+			NumEnums:      0,
+			NumMessages:   9,
+			NumExtensions: 0,
+			NumServices:   1,
+		},
+		GoTypes:           file_control_plane_proto_goTypes,
+		DependencyIndexes: file_control_plane_proto_depIdxs,
+		MessageInfos:      file_control_plane_proto_msgTypes,
+	}.Build()
+	File_control_plane_proto = out.File
+	file_control_plane_proto_goTypes = nil
+	file_control_plane_proto_depIdxs = nil
+}

pkg/messages/control_plane_grpc.pb.go

@@ -0,0 +1,327 @@
+// Code generated by protoc-gen-go-grpc. DO NOT EDIT.
+// versions:
+// - protoc-gen-go-grpc v1.5.1
+// - protoc             v6.33.1
+// source: control_plane.proto
+
+package messages
+
+import (
+	context "context"
+	grpc "google.golang.org/grpc"
+	codes "google.golang.org/grpc/codes"
+	status "google.golang.org/grpc/status"
+)
+
+// This is a compile-time assertion to ensure that this generated file
+// is compatible with the grpc package it is being compiled against.
+// Requires gRPC-Go v1.64.0 or later.
+const _ = grpc.SupportPackageIsVersion9
+
+const (
+	ControlPlane_Ping_FullMethodName              = "/messages.ControlPlane/Ping"
+	ControlPlane_Negotiate_FullMethodName         = "/messages.ControlPlane/Negotiate"
+	ControlPlane_GetLocalActorIds_FullMethodName  = "/messages.ControlPlane/GetLocalActorIds"
+	ControlPlane_AnnounceOwnership_FullMethodName = "/messages.ControlPlane/AnnounceOwnership"
+	ControlPlane_AnnounceExpiry_FullMethodName    = "/messages.ControlPlane/AnnounceExpiry"
+	ControlPlane_Closing_FullMethodName           = "/messages.ControlPlane/Closing"
+)
+
+// ControlPlaneClient is the client API for ControlPlane service.
+//
+// For semantics around ctx use and closing/ending streaming RPCs, please refer to https://pkg.go.dev/google.golang.org/grpc/?tab=doc#ClientConn.NewStream.
+//
+// ControlPlane defines cluster coordination and ownership operations.
+type ControlPlaneClient interface {
+	// Ping for liveness; lightweight health signal.
+	Ping(ctx context.Context, in *Empty, opts ...grpc.CallOption) (*PingReply, error)
+	// Negotiate merges host views; used during discovery & convergence.
+	Negotiate(ctx context.Context, in *NegotiateRequest, opts ...grpc.CallOption) (*NegotiateReply, error)
+	// GetCartIds lists currently owned cart IDs on this node.
+	GetLocalActorIds(ctx context.Context, in *Empty, opts ...grpc.CallOption) (*ActorIdsReply, error)
+	// Ownership announcement: first-touch claim broadcast (idempotent; best-effort).
+	AnnounceOwnership(ctx context.Context, in *OwnershipAnnounce, opts ...grpc.CallOption) (*OwnerChangeAck, error)
+	// Expiry announcement: drop remote ownership hints when local TTL expires.
+	AnnounceExpiry(ctx context.Context, in *ExpiryAnnounce, opts ...grpc.CallOption) (*OwnerChangeAck, error)
+	// Closing announces graceful shutdown so peers can proactively adjust.
+	Closing(ctx context.Context, in *ClosingNotice, opts ...grpc.CallOption) (*OwnerChangeAck, error)
+}
+
+type controlPlaneClient struct {
+	cc grpc.ClientConnInterface
+}
+
+func NewControlPlaneClient(cc grpc.ClientConnInterface) ControlPlaneClient {
+	return &controlPlaneClient{cc}
+}
+
+func (c *controlPlaneClient) Ping(ctx context.Context, in *Empty, opts ...grpc.CallOption) (*PingReply, error) {
+	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
+	out := new(PingReply)
+	err := c.cc.Invoke(ctx, ControlPlane_Ping_FullMethodName, in, out, cOpts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+func (c *controlPlaneClient) Negotiate(ctx context.Context, in *NegotiateRequest, opts ...grpc.CallOption) (*NegotiateReply, error) {
+	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
+	out := new(NegotiateReply)
+	err := c.cc.Invoke(ctx, ControlPlane_Negotiate_FullMethodName, in, out, cOpts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+func (c *controlPlaneClient) GetLocalActorIds(ctx context.Context, in *Empty, opts ...grpc.CallOption) (*ActorIdsReply, error) {
+	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
+	out := new(ActorIdsReply)
+	err := c.cc.Invoke(ctx, ControlPlane_GetLocalActorIds_FullMethodName, in, out, cOpts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+func (c *controlPlaneClient) AnnounceOwnership(ctx context.Context, in *OwnershipAnnounce, opts ...grpc.CallOption) (*OwnerChangeAck, error) {
+	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
+	out := new(OwnerChangeAck)
+	err := c.cc.Invoke(ctx, ControlPlane_AnnounceOwnership_FullMethodName, in, out, cOpts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+func (c *controlPlaneClient) AnnounceExpiry(ctx context.Context, in *ExpiryAnnounce, opts ...grpc.CallOption) (*OwnerChangeAck, error) {
+	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
+	out := new(OwnerChangeAck)
+	err := c.cc.Invoke(ctx, ControlPlane_AnnounceExpiry_FullMethodName, in, out, cOpts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+func (c *controlPlaneClient) Closing(ctx context.Context, in *ClosingNotice, opts ...grpc.CallOption) (*OwnerChangeAck, error) {
+	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
+	out := new(OwnerChangeAck)
+	err := c.cc.Invoke(ctx, ControlPlane_Closing_FullMethodName, in, out, cOpts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+// ControlPlaneServer is the server API for ControlPlane service.
+// All implementations must embed UnimplementedControlPlaneServer
+// for forward compatibility.
+//
+// ControlPlane defines cluster coordination and ownership operations.
+type ControlPlaneServer interface {
+	// Ping for liveness; lightweight health signal.
+	Ping(context.Context, *Empty) (*PingReply, error)
+	// Negotiate merges host views; used during discovery & convergence.
+	Negotiate(context.Context, *NegotiateRequest) (*NegotiateReply, error)
+	// GetCartIds lists currently owned cart IDs on this node.
+	GetLocalActorIds(context.Context, *Empty) (*ActorIdsReply, error)
+	// Ownership announcement: first-touch claim broadcast (idempotent; best-effort).
+	AnnounceOwnership(context.Context, *OwnershipAnnounce) (*OwnerChangeAck, error)
+	// Expiry announcement: drop remote ownership hints when local TTL expires.
+	AnnounceExpiry(context.Context, *ExpiryAnnounce) (*OwnerChangeAck, error)
+	// Closing announces graceful shutdown so peers can proactively adjust.
+	Closing(context.Context, *ClosingNotice) (*OwnerChangeAck, error)
+	mustEmbedUnimplementedControlPlaneServer()
+}
+
+// UnimplementedControlPlaneServer must be embedded to have
+// forward compatible implementations.
+//
+// NOTE: this should be embedded by value instead of pointer to avoid a nil
+// pointer dereference when methods are called.
+type UnimplementedControlPlaneServer struct{}
+
+func (UnimplementedControlPlaneServer) Ping(context.Context, *Empty) (*PingReply, error) {
+	return nil, status.Errorf(codes.Unimplemented, "method Ping not implemented")
+}
+func (UnimplementedControlPlaneServer) Negotiate(context.Context, *NegotiateRequest) (*NegotiateReply, error) {
+	return nil, status.Errorf(codes.Unimplemented, "method Negotiate not implemented")
+}
+func (UnimplementedControlPlaneServer) GetLocalActorIds(context.Context, *Empty) (*ActorIdsReply, error) {
+	return nil, status.Errorf(codes.Unimplemented, "method GetLocalActorIds not implemented")
+}
+func (UnimplementedControlPlaneServer) AnnounceOwnership(context.Context, *OwnershipAnnounce) (*OwnerChangeAck, error) {
+	return nil, status.Errorf(codes.Unimplemented, "method AnnounceOwnership not implemented")
+}
+func (UnimplementedControlPlaneServer) AnnounceExpiry(context.Context, *ExpiryAnnounce) (*OwnerChangeAck, error) {
+	return nil, status.Errorf(codes.Unimplemented, "method AnnounceExpiry not implemented")
+}
+func (UnimplementedControlPlaneServer) Closing(context.Context, *ClosingNotice) (*OwnerChangeAck, error) {
+	return nil, status.Errorf(codes.Unimplemented, "method Closing not implemented")
+}
+func (UnimplementedControlPlaneServer) mustEmbedUnimplementedControlPlaneServer() {}
+func (UnimplementedControlPlaneServer) testEmbeddedByValue()                      {}
+
+// UnsafeControlPlaneServer may be embedded to opt out of forward compatibility for this service.
+// Use of this interface is not recommended, as added methods to ControlPlaneServer will
+// result in compilation errors.
+type UnsafeControlPlaneServer interface {
+	mustEmbedUnimplementedControlPlaneServer()
+}
+
+func RegisterControlPlaneServer(s grpc.ServiceRegistrar, srv ControlPlaneServer) {
+	// If the following call pancis, it indicates UnimplementedControlPlaneServer was
+	// embedded by pointer and is nil.  This will cause panics if an
+	// unimplemented method is ever invoked, so we test this at initialization
+	// time to prevent it from happening at runtime later due to I/O.
+	if t, ok := srv.(interface{ testEmbeddedByValue() }); ok {
+		t.testEmbeddedByValue()
+	}
+	s.RegisterService(&ControlPlane_ServiceDesc, srv)
+}
+
+func _ControlPlane_Ping_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(Empty)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(ControlPlaneServer).Ping(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: ControlPlane_Ping_FullMethodName,
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(ControlPlaneServer).Ping(ctx, req.(*Empty))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
+func _ControlPlane_Negotiate_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(NegotiateRequest)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(ControlPlaneServer).Negotiate(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: ControlPlane_Negotiate_FullMethodName,
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(ControlPlaneServer).Negotiate(ctx, req.(*NegotiateRequest))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
+func _ControlPlane_GetLocalActorIds_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(Empty)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(ControlPlaneServer).GetLocalActorIds(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: ControlPlane_GetLocalActorIds_FullMethodName,
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(ControlPlaneServer).GetLocalActorIds(ctx, req.(*Empty))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
+func _ControlPlane_AnnounceOwnership_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(OwnershipAnnounce)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(ControlPlaneServer).AnnounceOwnership(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: ControlPlane_AnnounceOwnership_FullMethodName,
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(ControlPlaneServer).AnnounceOwnership(ctx, req.(*OwnershipAnnounce))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
+func _ControlPlane_AnnounceExpiry_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(ExpiryAnnounce)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(ControlPlaneServer).AnnounceExpiry(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: ControlPlane_AnnounceExpiry_FullMethodName,
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(ControlPlaneServer).AnnounceExpiry(ctx, req.(*ExpiryAnnounce))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
+func _ControlPlane_Closing_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(ClosingNotice)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(ControlPlaneServer).Closing(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: ControlPlane_Closing_FullMethodName,
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(ControlPlaneServer).Closing(ctx, req.(*ClosingNotice))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
+// ControlPlane_ServiceDesc is the grpc.ServiceDesc for ControlPlane service.
+// It's only intended for direct use with grpc.RegisterService,
+// and not to be introspected or modified (even as a copy)
+var ControlPlane_ServiceDesc = grpc.ServiceDesc{
+	ServiceName: "messages.ControlPlane",
+	HandlerType: (*ControlPlaneServer)(nil),
+	Methods: []grpc.MethodDesc{
+		{
+			MethodName: "Ping",
+			Handler:    _ControlPlane_Ping_Handler,
+		},
+		{
+			MethodName: "Negotiate",
+			Handler:    _ControlPlane_Negotiate_Handler,
+		},
+		{
+			MethodName: "GetLocalActorIds",
+			Handler:    _ControlPlane_GetLocalActorIds_Handler,
+		},
+		{
+			MethodName: "AnnounceOwnership",
+			Handler:    _ControlPlane_AnnounceOwnership_Handler,
+		},
+		{
+			MethodName: "AnnounceExpiry",
+			Handler:    _ControlPlane_AnnounceExpiry_Handler,
+		},
+		{
+			MethodName: "Closing",
+			Handler:    _ControlPlane_Closing_Handler,
+		},
+	},
+	Streams:  []grpc.StreamDesc{},
+	Metadata: "control_plane.proto",
+}

pkg/promotions/eval.go

@@ -0,0 +1,724 @@
+package promotions
+
+import (
+	"errors"
+	"fmt"
+	"slices"
+	"strings"
+	"time"
+
+	"git.tornberg.me/go-cart-actor/pkg/cart"
+)
+
+var errInvalidTimeFormat = errors.New("invalid time format")
+
+// Tracer allows callers to receive structured debug information during evaluation.
+type Tracer interface {
+	Trace(event string, data map[string]any)
+}
+
+// NoopTracer is used when no tracer provided.
+type NoopTracer struct{}
+
+func (NoopTracer) Trace(string, map[string]any) {}
+
+// PromotionItem is a lightweight abstraction derived from cart.CartItem
+// for the purpose of promotion condition evaluation.
+type PromotionItem struct {
+	SKU         string
+	Quantity    int
+	Category    string
+	PriceIncVat int64
+}
+
+// PromotionEvalContext carries all dynamic data required to evaluate promotion
+// conditions. It can be constructed from a cart.CartGrain plus optional
+// customer/order metadata.
+type PromotionEvalContext struct {
+	CartTotalIncVat       int64
+	TotalItemQuantity     int
+	Items                 []PromotionItem
+	CustomerSegment       string
+	CustomerLifetimeValue float64
+	OrderCount            int
+	Now                   time.Time
+}
+
+// ContextOption allows customization of fields when building a PromotionEvalContext.
+type ContextOption func(*PromotionEvalContext)
+
+// WithCustomerSegment sets the customer segment.
+func WithCustomerSegment(seg string) ContextOption {
+	return func(c *PromotionEvalContext) { c.CustomerSegment = seg }
+}
+
+// WithCustomerLifetimeValue sets lifetime value metric.
+func WithCustomerLifetimeValue(v float64) ContextOption {
+	return func(c *PromotionEvalContext) { c.CustomerLifetimeValue = v }
+}
+
+// WithOrderCount sets historical order count.
+func WithOrderCount(n int) ContextOption {
+	return func(c *PromotionEvalContext) { c.OrderCount = n }
+}
+
+// WithNow overrides the timestamp used for date/time related conditions.
+func WithNow(t time.Time) ContextOption {
+	return func(c *PromotionEvalContext) { c.Now = t }
+}
+
+// NewContextFromCart builds a PromotionEvalContext from a CartGrain and optional metadata.
+func NewContextFromCart(g *cart.CartGrain, opts ...ContextOption) *PromotionEvalContext {
+	ctx := &PromotionEvalContext{
+		Items:             make([]PromotionItem, 0, len(g.Items)),
+		CartTotalIncVat:   0,
+		TotalItemQuantity: 0,
+		Now:               time.Now(),
+	}
+	if g.TotalPrice != nil {
+		ctx.CartTotalIncVat = g.TotalPrice.IncVat
+	}
+	for _, it := range g.Items {
+		category := ""
+		if it.Meta != nil {
+			category = it.Meta.Category
+		}
+		ctx.Items = append(ctx.Items, PromotionItem{
+			SKU:         it.Sku,
+			Quantity:    it.Quantity,
+			Category:    strings.ToLower(category),
+			PriceIncVat: it.Price.IncVat,
+		})
+		ctx.TotalItemQuantity += it.Quantity
+	}
+	for _, o := range opts {
+		o(ctx)
+	}
+	return ctx
+}
+
+// PromotionService evaluates PromotionRules against a PromotionEvalContext.
+type PromotionService struct {
+	tracer Tracer
+}
+
+// NewPromotionService constructs a PromotionService with an optional tracer.
+func NewPromotionService(t Tracer) *PromotionService {
+	if t == nil {
+		t = NoopTracer{}
+	}
+	return &PromotionService{tracer: t}
+}
+
+// EvaluationResult holds the outcome of evaluating a single rule.
+type EvaluationResult struct {
+	Rule           PromotionRule
+	Applicable     bool
+	FailedReason   string
+	MatchedActions []Action
+}
+
+// EvaluateRule determines if a single PromotionRule applies to the provided context.
+// Returns an EvaluationResult with applicability and actions (if applicable).
+func (s *PromotionService) EvaluateRule(rule PromotionRule, ctx *PromotionEvalContext) EvaluationResult {
+	s.tracer.Trace("rule_start", map[string]any{
+		"rule_id":   rule.ID,
+		"priority":  rule.Priority,
+		"status":    rule.Status,
+		"startDate": rule.StartDate,
+		"endDate":   rule.EndDate,
+	})
+	// Status gate
+	now := ctx.Now
+	switch rule.Status {
+	case StatusInactive, StatusExpired:
+		s.tracer.Trace("rule_skip_status", map[string]any{"rule_id": rule.ID, "status": rule.Status})
+		return EvaluationResult{Rule: rule, Applicable: false, FailedReason: "status"}
+	case StatusScheduled:
+		// Allow scheduled only if current time >= startDate (and within endDate if present)
+	}
+	// Date window checks (if parseable)
+	if rule.StartDate != "" {
+		if tStart, err := parseDate(rule.StartDate); err == nil {
+			if now.Before(tStart) {
+				s.tracer.Trace("rule_skip_before_start", map[string]any{"rule_id": rule.ID})
+				return EvaluationResult{Rule: rule, Applicable: false, FailedReason: "before_start"}
+			}
+		}
+	}
+	if rule.EndDate != nil && *rule.EndDate != "" {
+		if tEnd, err := parseDate(*rule.EndDate); err == nil {
+			if now.After(tEnd.Add(23*time.Hour + 59*time.Minute + 59*time.Second)) { // inclusive day
+				s.tracer.Trace("rule_skip_after_end", map[string]any{"rule_id": rule.ID})
+				return EvaluationResult{Rule: rule, Applicable: false, FailedReason: "after_end"}
+			}
+		}
+	}
+	// Usage limit
+	if rule.UsageLimit != nil && rule.UsageCount >= *rule.UsageLimit {
+		s.tracer.Trace("rule_skip_usage_limit", map[string]any{"rule_id": rule.ID, "usageCount": rule.UsageCount, "limit": *rule.UsageLimit})
+		return EvaluationResult{Rule: rule, Applicable: false, FailedReason: "usage_limit_exhausted"}
+	}
+
+	if !evaluateConditionsTrace(rule.Conditions, ctx, s.tracer, rule.ID) {
+		s.tracer.Trace("rule_conditions_failed", map[string]any{"rule_id": rule.ID})
+		return EvaluationResult{Rule: rule, Applicable: false, FailedReason: "conditions"}
+	}
+
+	s.tracer.Trace("rule_applicable", map[string]any{"rule_id": rule.ID})
+	return EvaluationResult{
+		Rule:           rule,
+		Applicable:     true,
+		MatchedActions: rule.Actions,
+	}
+}
+
+// EvaluateAll returns all applicable promotion actions given a list of rules and context.
+// Rules marked Applicable are sorted by Priority (ascending: lower number = higher precedence).
+func (s *PromotionService) EvaluateAll(rules []PromotionRule, ctx *PromotionEvalContext) ([]EvaluationResult, []Action) {
+	results := make([]EvaluationResult, 0, len(rules))
+	for _, r := range rules {
+		res := s.EvaluateRule(r, ctx)
+		results = append(results, res)
+	}
+	actions := make([]Action, 0)
+	for _, res := range orderedByPriority(results) {
+		if res.Applicable {
+			s.tracer.Trace("actions_add", map[string]any{
+				"rule_id":  res.Rule.ID,
+				"count":    len(res.MatchedActions),
+				"priority": res.Rule.Priority,
+			})
+			actions = append(actions, res.MatchedActions...)
+		}
+	}
+	s.tracer.Trace("evaluation_complete", map[string]any{
+		"rules_total": len(rules),
+		"actions":     len(actions),
+	})
+	return results, actions
+}
+
+// orderedByPriority returns results sorted by PromotionRule.Priority ascending (stable).
+func orderedByPriority(in []EvaluationResult) []EvaluationResult {
+	out := make([]EvaluationResult, len(in))
+	copy(out, in)
+	for i := 1; i < len(out); i++ {
+		j := i
+		for j > 0 && out[j-1].Rule.Priority > out[j].Rule.Priority {
+			out[j-1], out[j] = out[j], out[j-1]
+			j--
+		}
+	}
+	return out
+}
+
+// ----------------------------
+// Condition evaluation (with tracing)
+// ----------------------------
+
+func evaluateConditionsTrace(conds Conditions, ctx *PromotionEvalContext, t Tracer, ruleID string) bool {
+	for idx, c := range conds {
+		if !evaluateConditionTrace(c, ctx, t, ruleID, fmt.Sprintf("root[%d]", idx)) {
+			return false
+		}
+	}
+	return true
+}
+
+func evaluateConditionTrace(c Condition, ctx *PromotionEvalContext, t Tracer, ruleID, path string) bool {
+	if grp, ok := c.(ConditionGroup); ok {
+		return evaluateGroupTrace(grp, ctx, t, ruleID, path)
+	}
+	bc, ok := c.(BaseCondition)
+	if !ok {
+		t.Trace("cond_invalid_type", map[string]any{"rule_id": ruleID, "path": path})
+		return false
+	}
+	res := evaluateBaseCondition(bc, ctx)
+	t.Trace("cond_base", map[string]any{
+		"rule_id": ruleID,
+		"path":    path,
+		"type":    bc.Type,
+		"op":      bc.Operator,
+		"value":   bc.Value.String(),
+		"result":  res,
+	})
+	return res
+}
+
+func evaluateGroupTrace(g ConditionGroup, ctx *PromotionEvalContext, t Tracer, ruleID, path string) bool {
+	op := normalizeLogicOperator(string(g.Operator))
+	if len(g.Conditions) == 0 {
+		t.Trace("cond_group_empty", map[string]any{"rule_id": ruleID, "path": path})
+		return true
+	}
+	if op == string(LogicAND) {
+		for i, child := range g.Conditions {
+			if !evaluateConditionTrace(child, ctx, t, ruleID, path+fmt.Sprintf(".AND[%d]", i)) {
+				t.Trace("cond_group_and_fail", map[string]any{"rule_id": ruleID, "path": path})
+				return false
+			}
+		}
+		t.Trace("cond_group_and_pass", map[string]any{"rule_id": ruleID, "path": path})
+		return true
+	}
+	for i, child := range g.Conditions {
+		if evaluateConditionTrace(child, ctx, t, ruleID, path+fmt.Sprintf(".OR[%d]", i)) {
+			t.Trace("cond_group_or_pass", map[string]any{"rule_id": ruleID, "path": path})
+			return true
+		}
+	}
+	t.Trace("cond_group_or_fail", map[string]any{"rule_id": ruleID, "path": path})
+	return false
+}
+
+// Fallback non-traced evaluation (used internally by traced path)
+func evaluateConditions(conds Conditions, ctx *PromotionEvalContext) bool {
+	for _, c := range conds {
+		if !evaluateCondition(c, ctx) {
+			return false
+		}
+	}
+	return true
+}
+
+func evaluateCondition(c Condition, ctx *PromotionEvalContext) bool {
+	if grp, ok := c.(ConditionGroup); ok {
+		return evaluateGroup(grp, ctx)
+	}
+	bc, ok := c.(BaseCondition)
+	if !ok {
+		return false
+	}
+	return evaluateBaseCondition(bc, ctx)
+}
+
+func evaluateGroup(g ConditionGroup, ctx *PromotionEvalContext) bool {
+	op := normalizeLogicOperator(string(g.Operator))
+	if len(g.Conditions) == 0 {
+		return true
+	}
+	if op == string(LogicAND) {
+		for _, child := range g.Conditions {
+			if !evaluateCondition(child, ctx) {
+				return false
+			}
+		}
+		return true
+	}
+	for _, child := range g.Conditions {
+		if evaluateCondition(child, ctx) {
+			return true
+		}
+	}
+	return false
+}
+
+func evaluateBaseCondition(b BaseCondition, ctx *PromotionEvalContext) bool {
+	switch b.Type {
+	case CondCartTotal:
+		return evalNumberCompare(float64(ctx.CartTotalIncVat), b)
+	case CondItemQuantity:
+		return evalNumberCompare(float64(ctx.TotalItemQuantity), b)
+	case CondCustomerSegment:
+		return evalStringCompare(ctx.CustomerSegment, b)
+	case CondProductCategory:
+		return evalAnyItemMatch(func(it PromotionItem) bool {
+			return evalValueAgainstTarget(strings.ToLower(it.Category), b)
+		}, b, ctx)
+	case CondProductID:
+		return evalAnyItemMatch(func(it PromotionItem) bool {
+			return evalValueAgainstTarget(strings.ToLower(it.SKU), b)
+		}, b, ctx)
+	case CondCustomerLifetime:
+		return evalNumberCompare(ctx.CustomerLifetimeValue, b)
+	case CondOrderCount:
+		return evalNumberCompare(float64(ctx.OrderCount), b)
+	case CondDateRange:
+		return evalDateRange(ctx.Now, b)
+	case CondDayOfWeek:
+		return evalDayOfWeek(ctx.Now, b)
+	case CondTimeOfDay:
+		return evalTimeOfDay(ctx.Now, b)
+	default:
+		return false
+	}
+}
+
+func evalAnyItemMatch(pred func(PromotionItem) bool, b BaseCondition, ctx *PromotionEvalContext) bool {
+	if slices.ContainsFunc(ctx.Items, pred) {
+		return true
+	}
+	switch normalizeOperator(string(b.Operator)) {
+	case string(OpNotIn), string(OpNotContains):
+		return true
+	}
+	return false
+}
+
+// ----------------------------
+// Primitive evaluators
+// ----------------------------
+
+func evalNumberCompare(target float64, b BaseCondition) bool {
+	op := normalizeOperator(string(b.Operator))
+	cond, ok := b.Value.AsFloat64()
+	if !ok {
+		if list, okL := b.Value.AsFloat64Slice(); okL && (op == string(OpIn) || op == string(OpNotIn)) {
+			found := sliceFloatContains(list, target)
+			if op == string(OpIn) {
+				return found
+			}
+			return !found
+		}
+		return false
+	}
+	switch op {
+	case string(OpEquals):
+		return target == cond
+	case string(OpNotEquals):
+		return target != cond
+	case string(OpGreaterThan):
+		return target > cond
+	case string(OpLessThan):
+		return target < cond
+	case string(OpGreaterOrEqual):
+		return target >= cond
+	case string(OpLessOrEqual):
+		return target <= cond
+	default:
+		return false
+	}
+}
+
+func evalStringCompare(target string, b BaseCondition) bool {
+	op := normalizeOperator(string(b.Operator))
+	targetLower := strings.ToLower(target)
+
+	if s, ok := b.Value.AsString(); ok {
+		condLower := strings.ToLower(s)
+		switch op {
+		case string(OpEquals):
+			return targetLower == condLower
+		case string(OpNotEquals):
+			return targetLower != condLower
+		case string(OpContains):
+			return strings.Contains(targetLower, condLower)
+		case string(OpNotContains):
+			return !strings.Contains(targetLower, condLower)
+		}
+	}
+
+	if arr, ok := b.Value.AsStringSlice(); ok {
+		switch op {
+		case string(OpIn):
+			for _, v := range arr {
+				if targetLower == strings.ToLower(v) {
+					return true
+				}
+			}
+			return false
+		case string(OpNotIn):
+			for _, v := range arr {
+				if targetLower == strings.ToLower(v) {
+					return false
+				}
+			}
+			return true
+		case string(OpContains):
+			for _, v := range arr {
+				if strings.Contains(targetLower, strings.ToLower(v)) {
+					return true
+				}
+			}
+			return false
+		case string(OpNotContains):
+			for _, v := range arr {
+				if strings.Contains(targetLower, strings.ToLower(v)) {
+					return false
+				}
+			}
+			return true
+		}
+	}
+
+	return false
+}
+
+func evalValueAgainstTarget(target string, b BaseCondition) bool {
+	op := normalizeOperator(string(b.Operator))
+	tLower := strings.ToLower(target)
+
+	if s, ok := b.Value.AsString(); ok {
+		vLower := strings.ToLower(s)
+		switch op {
+		case string(OpEquals):
+			return tLower == vLower
+		case string(OpNotEquals):
+			return tLower != vLower
+		case string(OpContains):
+			return strings.Contains(tLower, vLower)
+		case string(OpNotContains):
+			return !strings.Contains(tLower, vLower)
+		case string(OpIn):
+			return tLower == vLower
+		case string(OpNotIn):
+			return tLower != vLower
+		}
+	}
+
+	if list, ok := b.Value.AsStringSlice(); ok {
+		found := false
+		for _, v := range list {
+			if tLower == strings.ToLower(v) {
+				found = true
+				break
+			}
+		}
+		switch op {
+		case string(OpIn):
+			return found
+		case string(OpNotIn):
+			return !found
+		case string(OpContains):
+			for _, v := range list {
+				if strings.Contains(tLower, strings.ToLower(v)) {
+					return true
+				}
+			}
+			return false
+		case string(OpNotContains):
+			for _, v := range list {
+				if strings.Contains(tLower, strings.ToLower(v)) {
+					return false
+				}
+			}
+			return true
+		}
+	}
+
+	return false
+}
+
+func evalDateRange(now time.Time, b BaseCondition) bool {
+	var start, end time.Time
+	if ss, ok := b.Value.AsStringSlice(); ok && len(ss) == 2 {
+		t0, e0 := parseDate(ss[0])
+		t1, e1 := parseDate(ss[1])
+		if e0 != nil || e1 != nil {
+			return false
+		}
+		start, end = t0, t1
+	} else if s, ok := b.Value.AsString(); ok {
+		parts := strings.Split(s, "..")
+		if len(parts) != 2 {
+			return false
+		}
+		t0, e0 := parseDate(parts[0])
+		t1, e1 := parseDate(parts[1])
+		if e0 != nil || e1 != nil {
+			return false
+		}
+		start, end = t0, t1
+	} else {
+		return false
+	}
+	endInclusive := end.Add(23*time.Hour + 59*time.Minute + 59*time.Second)
+	return (now.Equal(start) || now.After(start)) && (now.Equal(endInclusive) || now.Before(endInclusive))
+}
+
+func evalDayOfWeek(now time.Time, b BaseCondition) bool {
+	dow := int(now.Weekday())
+	allowed := make(map[int]struct{})
+	if arr, ok := b.Value.AsStringSlice(); ok {
+		for _, v := range arr {
+			if idx, ok := parseDayOfWeek(v); ok {
+				allowed[idx] = struct{}{}
+			}
+		}
+	} else if s, ok := b.Value.AsString(); ok {
+		for _, part := range strings.Split(s, "|") {
+			if idx, ok := parseDayOfWeek(strings.TrimSpace(part)); ok {
+				allowed[idx] = struct{}{}
+			}
+		}
+	} else {
+		return false
+	}
+
+	if len(allowed) == 0 {
+		return false
+	}
+	op := normalizeOperator(string(b.Operator))
+	_, present := allowed[dow]
+	if op == string(OpIn) || op == string(OpEquals) || op == "" {
+		return present
+	}
+	if op == string(OpNotIn) || op == string(OpNotEquals) {
+		return !present
+	}
+	return present
+}
+
+func evalTimeOfDay(now time.Time, b BaseCondition) bool {
+	var startMin, endMin int
+	if arr, ok := b.Value.AsStringSlice(); ok && len(arr) == 2 {
+		s0, e0 := parseClock(arr[0])
+		s1, e1 := parseClock(arr[1])
+		if e0 != nil || e1 != nil {
+			return false
+		}
+		startMin, endMin = s0, s1
+	} else if s, ok := b.Value.AsString(); ok {
+		parts := strings.Split(s, "-")
+		if len(parts) != 2 {
+			return false
+		}
+		s0, e0 := parseClock(parts[0])
+		s1, e1 := parseClock(parts[1])
+		if e0 != nil || e1 != nil {
+			return false
+		}
+		startMin, endMin = s0, s1
+	} else {
+		return false
+	}
+	todayMin := now.Hour()*60 + now.Minute()
+	if startMin > endMin {
+		return todayMin >= startMin || todayMin <= endMin
+	}
+	return todayMin >= startMin && todayMin <= endMin
+}
+
+// ----------------------------
+// Parsing helpers
+// ----------------------------
+
+func parseDate(s string) (time.Time, error) {
+	layouts := []string{
+		"2006-01-02",
+		time.RFC3339,
+		"2006-01-02T15:04:05Z07:00",
+	}
+	for _, l := range layouts {
+		if t, err := time.Parse(l, strings.TrimSpace(s)); err == nil {
+			return t, nil
+		}
+	}
+	return time.Time{}, errInvalidTimeFormat
+}
+
+func parseDayOfWeek(s string) (int, bool) {
+	sl := strings.ToLower(strings.TrimSpace(s))
+	switch sl {
+	case "sun", "sunday", "0":
+		return 0, true
+	case "mon", "monday", "1":
+		return 1, true
+	case "tue", "tues", "tuesday", "2":
+		return 2, true
+	case "wed", "weds", "wednesday", "3":
+		return 3, true
+	case "thu", "thur", "thurs", "thursday", "4":
+		return 4, true
+	case "fri", "friday", "5":
+		return 5, true
+	case "sat", "saturday", "6":
+		return 6, true
+	default:
+		return 0, false
+	}
+}
+
+func parseClock(s string) (int, error) {
+	s = strings.TrimSpace(s)
+	parts := strings.Split(s, ":")
+	if len(parts) != 2 {
+		return 0, errInvalidTimeFormat
+	}
+	h, err := parsePositiveInt(parts[0])
+	if err != nil {
+		return 0, err
+	}
+	m, err := parsePositiveInt(parts[1])
+	if err != nil {
+		return 0, err
+	}
+	if h < 0 || h > 23 || m < 0 || m > 59 {
+		return 0, errInvalidTimeFormat
+	}
+	return h*60 + m, nil
+}
+
+func parsePositiveInt(s string) (int, error) {
+	n := 0
+	for _, r := range s {
+		if r < '0' || r > '9' {
+			return 0, errInvalidTimeFormat
+		}
+		n = n*10 + int(r-'0')
+	}
+	return n, nil
+}
+
+func normalizeOperator(op string) string {
+	o := strings.ToLower(strings.TrimSpace(op))
+	switch o {
+	case "=", "equals", "eq":
+		return string(OpEquals)
+	case "!=", "not_equals", "neq":
+		return string(OpNotEquals)
+	case ">", "greater_than", "gt":
+		return string(OpGreaterThan)
+	case "<", "less_than", "lt":
+		return string(OpLessThan)
+	case ">=", "greater_or_equal", "ge", "gte":
+		return string(OpGreaterOrEqual)
+	case "<=", "less_or_equal", "le", "lte":
+		return string(OpLessOrEqual)
+	case "contains":
+		return string(OpContains)
+	case "not_contains":
+		return string(OpNotContains)
+	case "in":
+		return string(OpIn)
+	case "not_in":
+		return string(OpNotIn)
+	default:
+		return o
+	}
+}
+
+func normalizeLogicOperator(op string) string {
+	o := strings.ToLower(strings.TrimSpace(op))
+	switch o {
+	case "&&", "and":
+		return string(LogicAND)
+	case "||", "or":
+		return string(LogicOR)
+	default:
+		return o
+	}
+}
+
+func sliceFloatContains(list []float64, v float64) bool {
+	return slices.Contains(list, v)
+}
+
+// ----------------------------
+// Potential extension hooks
+// ----------------------------
+//
+// Future ideas:
+//   - Conflict resolution strategies (e.g., best discount wins, stackable tags)
+//   - Action transformation (e.g., applying tiered logic or bundles carefully)
+//   - Recording evaluation traces for debugging / analytics.
+//   - Tracing instrumentation for condition evaluation.
+//
+// These can be integrated by adding strategy interfaces or injecting evaluators
+// into PromotionService.
+//
+// ----------------------------
+// End of file
+// ----------------------------

pkg/promotions/eval_test.go

@@ -0,0 +1,448 @@
+package promotions
+
+import (
+	"encoding/json"
+	"slices"
+	"testing"
+	"time"
+
+	"git.tornberg.me/go-cart-actor/pkg/cart"
+)
+
+// --- Helpers ---------------------------------------------------------------
+
+func cvNum(n float64) ConditionValue {
+	b, _ := json.Marshal(n)
+	return ConditionValue{Raw: b}
+}
+
+func cvString(s string) ConditionValue {
+	b, _ := json.Marshal(s)
+	return ConditionValue{Raw: b}
+}
+
+func cvStrings(ss []string) ConditionValue {
+	b, _ := json.Marshal(ss)
+	return ConditionValue{Raw: b}
+}
+
+// testTracer captures trace events for assertions.
+type testTracer struct {
+	events []traceEvent
+}
+
+type traceEvent struct {
+	event string
+	data  map[string]any
+}
+
+func (t *testTracer) Trace(event string, data map[string]any) {
+	t.events = append(t.events, traceEvent{event: event, data: data})
+}
+
+func (t *testTracer) HasEvent(name string) bool {
+	return slices.ContainsFunc(t.events, func(e traceEvent) bool { return e.event == name })
+}
+
+func (t *testTracer) Count(name string) int {
+	c := 0
+	for _, e := range t.events {
+		if e.event == name {
+			c++
+		}
+	}
+	return c
+}
+
+// makeCart creates a cart with given total and items (each item quantity & price IncVat).
+func makeCart(totalOverride int64, items []struct {
+	sku      string
+	category string
+	qty      int
+	priceInc int64
+}) *cart.CartGrain {
+	g := cart.NewCartGrain(1, time.Now())
+	for _, it := range items {
+		p := cart.NewPriceFromIncVat(it.priceInc, 0.25)
+		g.Items = append(g.Items, &cart.CartItem{
+			Id:    uint32(len(g.Items) + 1),
+			Sku:   it.sku,
+			Price: *p,
+			TotalPrice: cart.Price{
+				IncVat:   p.IncVat * int64(it.qty),
+				VatRates: p.VatRates,
+			},
+			Quantity: it.qty,
+			Meta: &cart.ItemMeta{
+				Category: it.category,
+			},
+		})
+	}
+	// Recalculate totals
+	g.UpdateTotals()
+	if totalOverride >= 0 {
+		g.TotalPrice.IncVat = totalOverride
+	}
+	return g
+}
+
+// --- Tests -----------------------------------------------------------------
+
+func TestEvaluateRuleBasicAND(t *testing.T) {
+	g := makeCart(12000, []struct {
+		sku      string
+		category string
+		qty      int
+		priceInc int64
+	}{
+		{"SKU-1", "summer", 2, 3000},
+		{"SKU-2", "winter", 1, 6000},
+	})
+
+	ctx := NewContextFromCart(g,
+		WithCustomerSegment("vip"),
+		WithOrderCount(10),
+		WithCustomerLifetimeValue(1234.56),
+		WithNow(time.Date(2024, 6, 10, 12, 0, 0, 0, time.UTC)),
+	)
+
+	// Conditions: cart_total >= 10000 AND item_quantity >= 3 AND customer_segment = vip
+	conds := Conditions{
+		ConditionGroup{
+			ID:       "grp",
+			Type:     "group",
+			Operator: LogicAND,
+			Conditions: Conditions{
+				BaseCondition{
+					ID:       "c_cart_total",
+					Type:     CondCartTotal,
+					Operator: OpGreaterOrEqual,
+					Value:    cvNum(10000),
+				},
+				BaseCondition{
+					ID:       "c_item_qty",
+					Type:     CondItemQuantity,
+					Operator: OpGreaterOrEqual,
+					Value:    cvNum(3),
+				},
+				BaseCondition{
+					ID:       "c_segment",
+					Type:     CondCustomerSegment,
+					Operator: OpEquals,
+					Value:    cvString("vip"),
+				},
+			},
+		},
+	}
+
+	rule := PromotionRule{
+		ID:          "rule-AND",
+		Name:        "VIP Summer",
+		Description: "Test rule",
+		Status:      StatusActive,
+		Priority:    1,
+		StartDate:   "2024-06-01",
+		EndDate:     ptr("2024-06-30"),
+		Conditions:  conds,
+		Actions: []Action{
+			{ID: "a1", Type: ActionPercentageDiscount, Value: 10.0},
+		},
+		UsageLimit: ptrInt(100),
+		UsageCount: 5,
+		CreatedAt:  time.Now().Format(time.RFC3339),
+		UpdatedAt:  time.Now().Format(time.RFC3339),
+		CreatedBy:  "tester",
+	}
+
+	tracer := &testTracer{}
+	svc := NewPromotionService(tracer)
+	res := svc.EvaluateRule(rule, ctx)
+	if !res.Applicable {
+		t.Fatalf("expected rule to be applicable, failedReason=%s", res.FailedReason)
+	}
+	if len(res.MatchedActions) != 1 {
+		t.Fatalf("expected 1 action, got %d", len(res.MatchedActions))
+	}
+	if !tracer.HasEvent("rule_applicable") {
+		t.Errorf("expected tracing event rule_applicable")
+	}
+}
+
+func TestEvaluateRuleUsageLimitExhausted(t *testing.T) {
+	rule := PromotionRule{
+		ID:         "limit",
+		Name:       "Limit",
+		Status:     StatusActive,
+		Priority:   1,
+		StartDate:  "2024-01-01",
+		EndDate:    nil,
+		Conditions: Conditions{},
+		UsageLimit: ptrInt(5),
+		UsageCount: 5,
+	}
+
+	ctx := &PromotionEvalContext{Now: time.Date(2024, 2, 1, 0, 0, 0, 0, time.UTC)}
+	tracer := &testTracer{}
+	svc := NewPromotionService(tracer)
+	res := svc.EvaluateRule(rule, ctx)
+	if res.Applicable {
+		t.Fatalf("expected rule NOT applicable due to usage limit")
+	}
+	if res.FailedReason != "usage_limit_exhausted" {
+		t.Fatalf("expected failedReason usage_limit_exhausted, got %s", res.FailedReason)
+	}
+	if !tracer.HasEvent("rule_skip_usage_limit") {
+		t.Errorf("tracer missing rule_skip_usage_limit event")
+	}
+}
+
+func TestEvaluateRuleDateWindow(t *testing.T) {
+	// Start in future
+	rule := PromotionRule{
+		ID:         "date",
+		Name:       "DateWindow",
+		Status:     StatusActive,
+		Priority:   1,
+		StartDate:  "2025-01-01",
+		EndDate:    ptr("2025-01-31"),
+		Conditions: Conditions{},
+	}
+	ctx := &PromotionEvalContext{Now: time.Date(2024, 12, 15, 12, 0, 0, 0, time.UTC)}
+	tracer := &testTracer{}
+	svc := NewPromotionService(tracer)
+	res := svc.EvaluateRule(rule, ctx)
+	if res.Applicable {
+		t.Fatalf("expected rule NOT applicable (before start)")
+	}
+	if res.FailedReason != "before_start" {
+		t.Fatalf("expected failedReason before_start, got %s", res.FailedReason)
+	}
+	if !tracer.HasEvent("rule_skip_before_start") {
+		t.Errorf("missing rule_skip_before_start trace event")
+	}
+}
+
+func TestEvaluateProductCategoryIN(t *testing.T) {
+	g := makeCart(-1, []struct {
+		sku      string
+		category string
+		qty      int
+		priceInc int64
+	}{
+		{"A", "shoes", 1, 5000},
+		{"B", "bags", 1, 7000},
+	})
+
+	ctx := NewContextFromCart(g)
+	conds := Conditions{
+		BaseCondition{
+			ID:       "c_category",
+			Type:     CondProductCategory,
+			Operator: OpIn,
+			Value:    cvStrings([]string{"shoes", "hats"}),
+		},
+	}
+	rule := PromotionRule{
+		ID:         "cat-in",
+		Status:     StatusActive,
+		Priority:   10,
+		StartDate:  "2024-01-01",
+		EndDate:    nil,
+		Conditions: conds,
+		Actions: []Action{
+			{ID: "discount", Type: ActionFixedDiscount, Value: 1000},
+		},
+	}
+	tracer := &testTracer{}
+	svc := NewPromotionService(tracer)
+	res := svc.EvaluateRule(rule, ctx)
+	if !res.Applicable {
+		t.Fatalf("expected category IN rule to apply")
+	}
+	if !tracer.HasEvent("rule_applicable") {
+		t.Errorf("tracing missing rule_applicable")
+	}
+}
+
+func TestEvaluateGroupOR(t *testing.T) {
+	g := makeCart(3000, []struct {
+		sku      string
+		category string
+		qty      int
+		priceInc int64
+	}{
+		{"ONE", "x", 1, 3000},
+	})
+
+	ctx := NewContextFromCart(g)
+
+	// OR group: (cart_total >= 10000) OR (item_quantity >= 1)
+	group := ConditionGroup{
+		ID:       "grp-or",
+		Type:     "group",
+		Operator: LogicOR,
+		Conditions: Conditions{
+			BaseCondition{
+				ID:       "c_total",
+				Type:     CondCartTotal,
+				Operator: OpGreaterOrEqual,
+				Value:    cvNum(10000),
+			},
+			BaseCondition{
+				ID:       "c_qty",
+				Type:     CondItemQuantity,
+				Operator: OpGreaterOrEqual,
+				Value:    cvNum(1),
+			},
+		},
+	}
+	rule := PromotionRule{
+		ID:         "or-rule",
+		Status:     StatusActive,
+		Priority:   5,
+		StartDate:  "2024-01-01",
+		EndDate:    nil,
+		Conditions: Conditions{group},
+		Actions:    []Action{{ID: "a", Type: ActionFixedDiscount, Value: 500}},
+	}
+	tracer := &testTracer{}
+	svc := NewPromotionService(tracer)
+	res := svc.EvaluateRule(rule, ctx)
+	if !res.Applicable {
+		t.Fatalf("expected OR rule to apply (second condition true)")
+	}
+	// Ensure group pass event
+	if !tracer.HasEvent("cond_group_or_pass") {
+		t.Errorf("expected cond_group_or_pass trace event")
+	}
+}
+
+func TestEvaluateAllPriorityOrdering(t *testing.T) {
+	ctx := &PromotionEvalContext{
+		CartTotalIncVat:   20000,
+		TotalItemQuantity: 2,
+		Items: []PromotionItem{
+			{SKU: "X", Quantity: 2, Category: "general", PriceIncVat: 10000},
+		},
+		Now: time.Date(2024, 5, 10, 10, 0, 0, 0, time.UTC),
+	}
+
+	// Rule A: priority 5
+	ruleA := PromotionRule{
+		ID:         "A",
+		Status:     StatusActive,
+		Priority:   5,
+		StartDate:  "2024-01-01",
+		EndDate:    nil,
+		Conditions: Conditions{},
+		Actions: []Action{
+			{ID: "actionA", Type: ActionFixedDiscount, Value: 100},
+		},
+	}
+
+	// Rule B: priority 1
+	ruleB := PromotionRule{
+		ID:         "B",
+		Status:     StatusActive,
+		Priority:   1,
+		StartDate:  "2024-01-01",
+		EndDate:    nil,
+		Conditions: Conditions{},
+		Actions: []Action{
+			{ID: "actionB", Type: ActionFixedDiscount, Value: 200},
+		},
+	}
+
+	tracer := &testTracer{}
+	svc := NewPromotionService(tracer)
+	results, actions := svc.EvaluateAll([]PromotionRule{ruleA, ruleB}, ctx)
+	if len(results) != 2 {
+		t.Fatalf("expected 2 results, got %d", len(results))
+	}
+	if len(actions) != 2 {
+		t.Fatalf("expected 2 actions, got %d", len(actions))
+	}
+
+	// Actions should follow priority order: ruleB (1) then ruleA (5)
+	if actions[0].ID != "actionB" || actions[1].ID != "actionA" {
+		t.Fatalf("actions order invalid: %+v", actions)
+	}
+	if tracer.Count("actions_add") != 2 {
+		t.Errorf("expected 2 actions_add trace events, got %d", tracer.Count("actions_add"))
+	}
+	if !tracer.HasEvent("evaluation_complete") {
+		t.Errorf("missing evaluation_complete trace")
+	}
+}
+
+func TestDayOfWeekAndTimeOfDay(t *testing.T) {
+	// Wednesday 14:30 UTC
+	now := time.Date(2024, 6, 12, 14, 30, 0, 0, time.UTC) // 2024-06-12 is Wednesday
+	ctx := &PromotionEvalContext{
+		Now: now,
+	}
+
+	condDay := BaseCondition{
+		ID:       "dow",
+		Type:     CondDayOfWeek,
+		Operator: OpIn,
+		Value:    cvStrings([]string{"wed", "fri"}),
+	}
+	condTime := BaseCondition{
+		ID:       "tod",
+		Type:     CondTimeOfDay,
+		Operator: OpEquals, // operator is ignored for time-of-day internally
+		Value:    cvString("13:00-15:00"),
+	}
+
+	rule := PromotionRule{
+		ID:         "day-time",
+		Status:     StatusActive,
+		Priority:   1,
+		StartDate:  "2024-01-01",
+		EndDate:    nil,
+		Conditions: Conditions{condDay, condTime},
+		Actions:    []Action{{ID: "a", Type: ActionPercentageDiscount, Value: 15}},
+	}
+
+	tracer := &testTracer{}
+	svc := NewPromotionService(tracer)
+	res := svc.EvaluateRule(rule, ctx)
+	if !res.Applicable {
+		t.Fatalf("expected rule to apply for Wednesday 14:30 in window 13-15")
+	}
+}
+
+func TestDateRangeCondition(t *testing.T) {
+	now := time.Date(2024, 3, 15, 9, 0, 0, 0, time.UTC)
+	ctx := &PromotionEvalContext{Now: now}
+
+	condRange := BaseCondition{
+		ID:       "date_range",
+		Type:     CondDateRange,
+		Operator: OpEquals, // not used
+		Value:    cvStrings([]string{"2024-03-01", "2024-03-31"}),
+	}
+
+	rule := PromotionRule{
+		ID:         "range",
+		Status:     StatusActive,
+		Priority:   1,
+		StartDate:  "2024-01-01",
+		EndDate:    nil,
+		Conditions: Conditions{condRange},
+		Actions:    []Action{{ID: "a", Type: ActionFixedDiscount, Value: 500}},
+	}
+
+	tracer := &testTracer{}
+	svc := NewPromotionService(tracer)
+	res := svc.EvaluateRule(rule, ctx)
+	if !res.Applicable {
+		t.Fatalf("expected date range rule to apply for 2024-03-15")
+	}
+}
+
+// --- Utilities -------------------------------------------------------------
+
+func ptr(s string) *string { return &s }
+func ptrInt(i int) *int    { return &i }

pkg/promotions/type_test.go

@@ -0,0 +1,443 @@
+package promotions
+
+import (
+	"encoding/json"
+	"testing"
+)
+
+// sampleJSON mirrors the user's full example data (all three rules)
+var sampleJSON = []byte(`[
+  {
+    "id": "1",
+    "name": "Summer Sale 2024",
+    "description": "20% off on all summer items",
+    "status": "active",
+    "priority": 1,
+    "startDate": "2024-06-01",
+    "endDate": "2024-08-31",
+    "conditions": [
+      {
+        "id": "group1",
+        "type": "group",
+        "operator": "AND",
+        "conditions": [
+          {
+            "id": "c1",
+            "type": "product_category",
+            "operator": "in",
+            "value": ["summer", "beachwear"],
+            "label": "Product category is Summer or Beachwear"
+          },
+          {
+            "id": "c2",
+            "type": "cart_total",
+            "operator": "greater_or_equal",
+            "value": 50,
+            "label": "Cart total is at least $50"
+          }
+        ]
+      }
+    ],
+    "actions": [
+      {
+        "id": "a1",
+        "type": "percentage_discount",
+        "value": 20,
+        "label": "20% discount"
+      }
+    ],
+    "usageLimit": 1000,
+    "usageCount": 342,
+    "createdAt": "2024-05-15T10:00:00Z",
+    "updatedAt": "2024-05-20T14:30:00Z",
+    "createdBy": "admin@example.com",
+    "tags": ["seasonal", "summer"]
+  },
+  {
+    "id": "2",
+    "name": "VIP Customer Exclusive",
+    "description": "Free shipping for VIP customers",
+    "status": "active",
+    "priority": 2,
+    "startDate": "2024-01-01",
+    "endDate": null,
+    "conditions": [
+      {
+        "id": "c3",
+        "type": "customer_segment",
+        "operator": "equals",
+        "value": "vip",
+        "label": "Customer segment is VIP"
+      }
+    ],
+    "actions": [
+      {
+        "id": "a2",
+        "type": "free_shipping",
+        "value": 0,
+        "label": "Free shipping"
+      }
+    ],
+    "usageCount": 1523,
+    "createdAt": "2023-12-15T09:00:00Z",
+    "updatedAt": "2024-01-05T11:20:00Z",
+    "createdBy": "marketing@example.com",
+    "tags": ["vip", "loyalty"]
+  },
+  {
+    "id": "3",
+    "name": "Buy 2 Get 1 Free",
+    "description": "Buy 2 items, get the cheapest one free",
+    "status": "scheduled",
+    "priority": 3,
+    "startDate": "2024-12-01",
+    "endDate": "2024-12-25",
+    "conditions": [
+      {
+        "id": "c4",
+        "type": "item_quantity",
+        "operator": "greater_or_equal",
+        "value": 3,
+        "label": "Cart has at least 3 items"
+      }
+    ],
+    "actions": [
+      {
+        "id": "a3",
+        "type": "buy_x_get_y",
+        "value": 0,
+        "config": { "buy": 2, "get": 1, "discount": 100 },
+        "label": "Buy 2 Get 1 Free"
+      }
+    ],
+    "usageCount": 0,
+    "createdAt": "2024-11-01T08:00:00Z",
+    "updatedAt": "2024-11-01T08:00:00Z",
+    "createdBy": "admin@example.com",
+    "tags": ["holiday", "christmas"]
+  }
+]`)
+
+func TestDecodePromotionRulesBasic(t *testing.T) {
+	rules, err := DecodePromotionRules(sampleJSON)
+	if err != nil {
+		t.Fatalf("DecodePromotionRules failed: %v", err)
+	}
+	if len(rules) != 3 {
+		t.Fatalf("expected 3 rules, got %d", len(rules))
+	}
+
+	// Rule 1 checks
+	r1 := rules[0]
+	if r1.ID != "1" {
+		t.Errorf("rule[0].ID = %s, want 1", r1.ID)
+	}
+	if r1.Status != StatusActive {
+		t.Errorf("rule[0].Status = %s, want %s", r1.Status, StatusActive)
+	}
+	if r1.EndDate == nil || *r1.EndDate != "2024-08-31" {
+		t.Errorf("rule[0].EndDate = %v, want 2024-08-31", r1.EndDate)
+	}
+	if r1.UsageLimit == nil || *r1.UsageLimit != 1000 {
+		t.Errorf("rule[0].UsageLimit = %v, want 1000", r1.UsageLimit)
+	}
+
+	// Rule 2 checks
+	r2 := rules[1]
+	if r2.ID != "2" {
+		t.Errorf("rule[1].ID = %s, want 2", r2.ID)
+	}
+	if r2.EndDate != nil {
+		t.Errorf("rule[1].EndDate should be nil (from null), got %v", *r2.EndDate)
+	}
+	if r2.UsageLimit != nil {
+		t.Errorf("rule[1].UsageLimit should be nil (missing), got %v", *r2.UsageLimit)
+	}
+}
+
+func TestConditionDecoding(t *testing.T) {
+	rules, err := DecodePromotionRules(sampleJSON)
+	if err != nil {
+		t.Fatalf("DecodePromotionRules failed: %v", err)
+	}
+	r1 := rules[0]
+	if len(r1.Conditions) != 1 {
+		t.Fatalf("expected 1 top-level condition group, got %d", len(r1.Conditions))
+	}
+
+	grp, ok := r1.Conditions[0].(ConditionGroup)
+	if !ok {
+		t.Fatalf("top-level condition is not a group, type=%T", r1.Conditions[0])
+	}
+	if grp.Operator != LogicAND {
+		t.Errorf("group operator = %s, want AND", grp.Operator)
+	}
+
+	if len(grp.Conditions) != 2 {
+		t.Fatalf("expected 2 child conditions, got %d", len(grp.Conditions))
+	}
+
+	// First child: product_category condition with slice value
+	c0, ok := grp.Conditions[0].(BaseCondition)
+	if !ok {
+		t.Fatalf("first child not BaseCondition, got %T", grp.Conditions[0])
+	}
+	if c0.Type != CondProductCategory {
+		t.Errorf("first child type = %s, want %s", c0.Type, CondProductCategory)
+	}
+	if c0.Operator != OpIn {
+		t.Errorf("first child operator = %s, want %s", c0.Operator, OpIn)
+	}
+	if arr, ok := c0.Value.AsStringSlice(); !ok || len(arr) != 2 || arr[0] != "summer" {
+		t.Errorf("expected string slice value [summer,...], got %v", arr)
+	}
+
+	// Second child: cart_total numeric
+	c1, ok := grp.Conditions[1].(BaseCondition)
+	if !ok {
+		t.Fatalf("second child not BaseCondition, got %T", grp.Conditions[1])
+	}
+	if c1.Type != CondCartTotal {
+		t.Errorf("second child type = %s, want %s", c1.Type, CondCartTotal)
+	}
+	if val, ok := c1.Value.AsFloat64(); !ok || val != 50 {
+		t.Errorf("expected numeric value 50, got %v (ok=%v)", val, ok)
+	}
+}
+
+func TestConditionValueHelpers(t *testing.T) {
+	tests := []struct {
+		name    string
+		jsonVal string
+		wantStr string
+		wantNum *float64
+		wantSS  []string
+		wantFS  []float64
+	}{
+		{
+			name:    "string value",
+			jsonVal: `"vip"`,
+			wantStr: "vip",
+		},
+		{
+			name:    "number value",
+			jsonVal: `42`,
+			wantNum: floatPtr(42),
+		},
+		{
+			name:    "string slice",
+			jsonVal: `["a","b"]`,
+			wantSS:  []string{"a", "b"},
+		},
+		{
+			name:    "number slice int",
+			jsonVal: `[1,2,3]`,
+			wantFS:  []float64{1, 2, 3},
+		},
+		{
+			name:    "number slice float",
+			jsonVal: `[1.5,2.25]`,
+			wantFS:  []float64{1.5, 2.25},
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			var cv ConditionValue
+			if err := json.Unmarshal([]byte(tc.jsonVal), &cv); err != nil {
+				t.Fatalf("unmarshal value failed: %v", err)
+			}
+			if tc.wantStr != "" {
+				if got, ok := cv.AsString(); !ok || got != tc.wantStr {
+					t.Errorf("AsString got=%q ok=%v want=%q", got, ok, tc.wantStr)
+				}
+			}
+			if tc.wantNum != nil {
+				if got, ok := cv.AsFloat64(); !ok || got != *tc.wantNum {
+					t.Errorf("AsFloat64 got=%v ok=%v want=%v", got, ok, *tc.wantNum)
+				}
+			}
+			if tc.wantSS != nil {
+				if got, ok := cv.AsStringSlice(); !ok || len(got) != len(tc.wantSS) || got[0] != tc.wantSS[0] {
+					t.Errorf("AsStringSlice got=%v ok=%v want=%v", got, ok, tc.wantSS)
+				}
+			}
+			if tc.wantFS != nil {
+				if got, ok := cv.AsFloat64Slice(); !ok || len(got) != len(tc.wantFS) {
+					t.Errorf("AsFloat64Slice got=%v ok=%v want=%v", got, ok, tc.wantFS)
+				} else {
+					for i := range got {
+						if got[i] != tc.wantFS[i] {
+							t.Errorf("AsFloat64Slice[%d]=%v want=%v", i, got[i], tc.wantFS[i])
+						}
+					}
+				}
+			}
+		})
+	}
+}
+
+func TestWalkConditionsTraversal(t *testing.T) {
+	rules, err := DecodePromotionRules(sampleJSON)
+	if err != nil {
+		t.Fatalf("DecodePromotionRules failed: %v", err)
+	}
+	visited := 0
+	WalkConditions(rules[0].Conditions, func(c Condition) bool {
+		visited++
+		return true
+	})
+	// group + 2 children
+	if visited != 3 {
+		t.Errorf("expected 3 visited conditions, got %d", visited)
+	}
+}
+
+func TestActionBundleConfigParsing(t *testing.T) {
+	jsonData := []byte(`[
+	  {
+	    "id": "bundle-1",
+	    "name": "Bundle Deal",
+	    "description": "Fixed price bundle",
+	    "status": "active",
+	    "priority": 1,
+	    "startDate": "2024-01-01",
+	    "endDate": null,
+	    "conditions": [],
+	    "actions": [
+	      {
+	        "id": "act-bundle",
+	        "type": "bundle_discount",
+	        "value": 0,
+	        "bundleConfig": {
+	          "containers": [
+	            {
+	              "id": "cont1",
+	              "name": "Shoes",
+	              "quantity": 2,
+	              "selectionType": "any",
+	              "qualifyingRules": {
+	                "type": "category",
+	                "value": "shoes"
+	              }
+	            },
+	            {
+	              "id": "cont2",
+	              "name": "Socks",
+	              "quantity": 3,
+	              "selectionType": "specific",
+	              "qualifyingRules": {
+	                "type": "product_ids",
+	                "value": ["sock-1", "sock-2"]
+	              },
+	              "allowedProducts": ["sock-1","sock-2"]
+	            }
+	          ],
+	          "pricing": {
+	            "type": "fixed_price",
+	            "value": 49.99
+	          },
+	          "requireAllContainers": true
+	        },
+	        "config": { "note": "Bundle applies to footwear + socks" }
+	      }
+	    ],
+	    "usageCount": 0,
+	    "createdAt": "2024-01-01T00:00:00Z",
+	    "updatedAt": "2024-01-01T00:00:00Z",
+	    "createdBy": "bundle@example.com",
+	    "tags": ["bundle","footwear"]
+	  }
+	]`)
+	rules, err := DecodePromotionRules(jsonData)
+	if err != nil {
+		t.Fatalf("decode failed: %v", err)
+	}
+	if len(rules) != 1 {
+		t.Fatalf("expected 1 rule, got %d", len(rules))
+	}
+	if len(rules[0].Actions) != 1 {
+		t.Fatalf("expected 1 action, got %d", len(rules[0].Actions))
+	}
+	act := rules[0].Actions[0]
+	if act.Type != ActionBundleDiscount {
+		t.Fatalf("action type = %s, want %s", act.Type, ActionBundleDiscount)
+	}
+	if act.BundleConfig == nil {
+		t.Fatalf("bundleConfig nil")
+	}
+	if act.BundleConfig.Pricing.Type != "fixed_price" {
+		t.Errorf("pricing.type = %s, want fixed_price", act.BundleConfig.Pricing.Type)
+	}
+	if act.BundleConfig.Pricing.Value != 49.99 {
+		t.Errorf("pricing.value = %v, want 49.99", act.BundleConfig.Pricing.Value)
+	}
+	if !act.BundleConfig.RequireAllContainers {
+		t.Errorf("RequireAllContainers expected true")
+	}
+	if len(act.BundleConfig.Containers) != 2 {
+		t.Fatalf("expected 2 containers, got %d", len(act.BundleConfig.Containers))
+	}
+	if act.Config == nil || act.Config["note"] != "Bundle applies to footwear + socks" {
+		t.Errorf("config.note mismatch: %v", act.Config)
+	}
+}
+
+func TestConditionValueInvalidTypes(t *testing.T) {
+	cases := []struct {
+		name string
+		raw  string
+	}{
+		{"object", `{}`},
+		{"booleanTrue", `true`},
+		{"booleanFalse", `false`},
+		{"null", `null`},
+	}
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			var cv ConditionValue
+			if err := json.Unmarshal([]byte(tc.raw), &cv); err != nil {
+				t.Fatalf("unmarshal failed: %v", err)
+			}
+			if s, ok := cv.AsString(); ok {
+				t.Errorf("AsString unexpectedly succeeded (%q) for %s", s, tc.name)
+			}
+			if n, ok := cv.AsFloat64(); ok {
+				t.Errorf("AsFloat64 unexpectedly succeeded (%v) for %s", n, tc.name)
+			}
+			if ss, ok := cv.AsStringSlice(); ok {
+				t.Errorf("AsStringSlice unexpectedly succeeded (%v) for %s", ss, tc.name)
+			}
+			if fs, ok := cv.AsFloat64Slice(); ok {
+				t.Errorf("AsFloat64Slice unexpectedly succeeded (%v) for %s", fs, tc.name)
+			}
+		})
+	}
+}
+
+func TestPromotionRuleRoundTrip(t *testing.T) {
+	orig, err := DecodePromotionRules(sampleJSON)
+	if err != nil {
+		t.Fatalf("initial decode failed: %v", err)
+	}
+	data, err := json.Marshal(orig)
+	if err != nil {
+		t.Fatalf("marshal failed: %v", err)
+	}
+	round, err := DecodePromotionRules(data)
+	if err != nil {
+		t.Fatalf("round-trip decode failed: %v", err)
+	}
+	if len(orig) != len(round) {
+		t.Fatalf("rule count mismatch: orig=%d round=%d", len(orig), len(round))
+	}
+	// spot-check first rule
+	if orig[0].Name != round[0].Name {
+		t.Errorf("first rule name mismatch: %s vs %s", orig[0].Name, round[0].Name)
+	}
+	if len(orig[0].Conditions) != len(round[0].Conditions) {
+		t.Errorf("first rule condition count mismatch: %d vs %d", len(orig[0].Conditions), len(round[0].Conditions))
+	}
+}
+
+func floatPtr(f float64) *float64 { return &f }

pkg/promotions/types.go

@@ -0,0 +1,413 @@
+package promotions
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+)
+
+// -----------------------------
+// Enum-like string types
+// -----------------------------
+
+type ConditionOperator string
+
+const (
+	OpEquals         ConditionOperator = "="
+	OpNotEquals      ConditionOperator = "!="
+	OpGreaterThan    ConditionOperator = ">"
+	OpLessThan       ConditionOperator = "<"
+	OpGreaterOrEqual ConditionOperator = ">="
+	OpLessOrEqual    ConditionOperator = "<="
+	OpContains       ConditionOperator = "contains"
+	OpNotContains    ConditionOperator = "not_contains"
+	OpIn             ConditionOperator = "in"
+	OpNotIn          ConditionOperator = "not_in"
+)
+
+type ConditionType string
+
+const (
+	CondCartTotal        ConditionType = "cart_total"
+	CondItemQuantity     ConditionType = "item_quantity"
+	CondCustomerSegment  ConditionType = "customer_segment"
+	CondProductCategory  ConditionType = "product_category"
+	CondProductID        ConditionType = "product_id"
+	CondCustomerLifetime ConditionType = "customer_lifetime_value"
+	CondOrderCount       ConditionType = "order_count"
+	CondDateRange        ConditionType = "date_range"
+	CondDayOfWeek        ConditionType = "day_of_week"
+	CondTimeOfDay        ConditionType = "time_of_day"
+	CondGroup            ConditionType = "group" // synthetic value for groups
+)
+
+type ActionType string
+
+const (
+	ActionPercentageDiscount ActionType = "percentage_discount"
+	ActionFixedDiscount      ActionType = "fixed_discount"
+	ActionFreeShipping       ActionType = "free_shipping"
+	ActionBuyXGetY           ActionType = "buy_x_get_y"
+	ActionTieredDiscount     ActionType = "tiered_discount"
+	ActionBundleDiscount     ActionType = "bundle_discount"
+)
+
+type LogicOperator string
+
+const (
+	LogicAND LogicOperator = "&&"
+	LogicOR  LogicOperator = "||"
+)
+
+type PromotionStatus string
+
+const (
+	StatusActive    PromotionStatus = "active"
+	StatusInactive  PromotionStatus = "inactive"
+	StatusScheduled PromotionStatus = "scheduled"
+	StatusExpired   PromotionStatus = "expired"
+)
+
+// -----------------------------
+// Condition Value (union)
+// -----------------------------
+//
+// Represents: string | number | []string | []number
+// We store raw JSON and lazily interpret.
+
+type ConditionValue struct {
+	Raw json.RawMessage
+}
+
+func (cv *ConditionValue) UnmarshalJSON(b []byte) error {
+	if len(b) == 0 {
+		return errors.New("empty ConditionValue")
+	}
+	// Just store raw; interpretation happens via helpers.
+	cv.Raw = append(cv.Raw[0:0], b...)
+	return nil
+}
+
+// Helpers to interpret value:
+func (cv ConditionValue) AsString() (string, bool) {
+	// Treat explicit JSON null as invalid
+	if string(cv.Raw) == "null" {
+		return "", false
+	}
+	var s string
+	if err := json.Unmarshal(cv.Raw, &s); err == nil {
+		return s, true
+	}
+	return "", false
+}
+
+func (cv ConditionValue) AsFloat64() (float64, bool) {
+	if string(cv.Raw) == "null" {
+		return 0, false
+	}
+	var f float64
+	if err := json.Unmarshal(cv.Raw, &f); err == nil {
+		return f, true
+	}
+	// Attempt integer decode into float64
+	var i int64
+	if err := json.Unmarshal(cv.Raw, &i); err == nil {
+		return float64(i), true
+	}
+	return 0, false
+}
+
+func (cv ConditionValue) AsStringSlice() ([]string, bool) {
+	if string(cv.Raw) == "null" {
+		return nil, false
+	}
+	var arr []string
+	if err := json.Unmarshal(cv.Raw, &arr); err == nil {
+		return arr, true
+	}
+	return nil, false
+}
+
+func (cv ConditionValue) AsFloat64Slice() ([]float64, bool) {
+	if string(cv.Raw) == "null" {
+		return nil, false
+	}
+	var arrNum []float64
+	if err := json.Unmarshal(cv.Raw, &arrNum); err == nil {
+		return arrNum, true
+	}
+	// Try []int -> []float64
+	var arrInt []int64
+	if err := json.Unmarshal(cv.Raw, &arrInt); err == nil {
+		out := make([]float64, len(arrInt))
+		for i, v := range arrInt {
+			out[i] = float64(v)
+		}
+		return out, true
+	}
+	return nil, false
+}
+
+func (cv ConditionValue) String() string {
+	if s, ok := cv.AsString(); ok {
+		return s
+	}
+	if f, ok := cv.AsFloat64(); ok {
+		return strconv.FormatFloat(f, 'f', -1, 64)
+	}
+	if ss, ok := cv.AsStringSlice(); ok {
+		return fmt.Sprintf("%v", ss)
+	}
+	if fs, ok := cv.AsFloat64Slice(); ok {
+		return fmt.Sprintf("%v", fs)
+	}
+	return string(cv.Raw)
+}
+
+// -----------------------------
+// BaseCondition
+// -----------------------------
+
+type BaseCondition struct {
+	ID       string            `json:"id"`
+	Type     ConditionType     `json:"type"`
+	Operator ConditionOperator `json:"operator"`
+	Value    ConditionValue    `json:"value"`
+	Label    *string           `json:"label,omitempty"`
+}
+
+func (b BaseCondition) IsGroup() bool { return false }
+
+// -----------------------------
+// ConditionGroup
+// -----------------------------
+
+type ConditionGroup struct {
+	ID         string        `json:"id"`
+	Type       string        `json:"type"` // always "group"
+	Operator   LogicOperator `json:"operator"`
+	Conditions Conditions    `json:"conditions"`
+}
+
+// Custom unmarshaller ensures nested polymorphic conditions are decoded
+// using the Conditions type (which applies the raw element discriminator).
+func (g *ConditionGroup) UnmarshalJSON(b []byte) error {
+	type alias struct {
+		ID         string          `json:"id"`
+		Type       string          `json:"type"`
+		Operator   LogicOperator   `json:"operator"`
+		Conditions json.RawMessage `json:"conditions"`
+	}
+	var a alias
+	if err := json.Unmarshal(b, &a); err != nil {
+		return err
+	}
+	// Basic validation
+	if a.Type != "group" {
+		return fmt.Errorf("ConditionGroup expected type 'group', got %q", a.Type)
+	}
+
+	var conds Conditions
+	if len(a.Conditions) > 0 {
+		if err := json.Unmarshal(a.Conditions, &conds); err != nil {
+			return err
+		}
+	}
+
+	g.ID = a.ID
+	g.Type = a.Type
+	switch strings.ToLower(string(a.Operator)) {
+	case "and":
+		g.Operator = LogicAND
+	case "or":
+		g.Operator = LogicOR
+	default:
+		g.Operator = a.Operator
+	}
+	g.Conditions = conds
+	return nil
+}
+
+func (g ConditionGroup) IsGroup() bool { return true }
+
+// -----------------------------
+// Condition interface + slice
+// -----------------------------
+
+type Condition interface {
+	IsGroup() bool
+}
+
+// Internal wrapper to help decode each element.
+type rawCond struct {
+	Type string `json:"type"`
+}
+
+// Custom unmarshaler for a Condition slice
+type Conditions []Condition
+
+func (cs *Conditions) UnmarshalJSON(b []byte) error {
+	var rawList []json.RawMessage
+	if err := json.Unmarshal(b, &rawList); err != nil {
+		return err
+	}
+	out := make([]Condition, 0, len(rawList))
+	for _, elem := range rawList {
+		var hdr rawCond
+		if err := json.Unmarshal(elem, &hdr); err != nil {
+			return err
+		}
+		if hdr.Type == "group" {
+			var grp ConditionGroup
+			if err := json.Unmarshal(elem, &grp); err != nil {
+				return err
+			}
+			// Recursively decode grp.Conditions (already handled because field type is []Condition)
+			out = append(out, grp)
+		} else {
+			var bc BaseCondition
+			if err := json.Unmarshal(elem, &bc); err != nil {
+				return err
+			}
+			out = append(out, bc)
+		}
+	}
+	*cs = out
+	return nil
+}
+
+// -----------------------------
+// Bundle Structures
+// -----------------------------
+
+type BundleQualifyingRules struct {
+	Type  string      `json:"type"`  // "category" | "product_ids" | "tag" | "all"
+	Value interface{} `json:"value"` // string or []string
+}
+
+type BundleContainer struct {
+	ID              string                `json:"id"`
+	Name            string                `json:"name"`
+	Quantity        int                   `json:"quantity"`
+	SelectionType   string                `json:"selectionType"` // "any" | "specific"
+	QualifyingRules BundleQualifyingRules `json:"qualifyingRules"`
+	AllowedProducts []string              `json:"allowedProducts,omitempty"`
+}
+
+type BundlePricing struct {
+	Type  string  `json:"type"` // "fixed_price" | "percentage_discount" | "fixed_discount"
+	Value float64 `json:"value"`
+}
+
+type BundleConfig struct {
+	Containers           []BundleContainer `json:"containers"`
+	Pricing              BundlePricing     `json:"pricing"`
+	RequireAllContainers bool              `json:"requireAllContainers"`
+}
+
+// -----------------------------
+// Action
+// -----------------------------
+
+type Action struct {
+	ID           string                 `json:"id"`
+	Type         ActionType             `json:"type"`
+	Value        interface{}            `json:"value"` // number or string
+	Config       map[string]interface{} `json:"config,omitempty"`
+	BundleConfig *BundleConfig          `json:"bundleConfig,omitempty"`
+	Label        *string                `json:"label,omitempty"`
+}
+
+// -----------------------------
+// Promotion Rule
+// -----------------------------
+
+type PromotionRule struct {
+	ID          string          `json:"id"`
+	Name        string          `json:"name"`
+	Description string          `json:"description"`
+	Status      PromotionStatus `json:"status"`
+	Priority    int             `json:"priority"`
+	StartDate   string          `json:"startDate"`
+	EndDate     *string         `json:"endDate"` // null -> nil
+	Conditions  Conditions      `json:"conditions"`
+	Actions     []Action        `json:"actions"`
+	UsageLimit  *int            `json:"usageLimit,omitempty"`
+	UsageCount  int             `json:"usageCount"`
+	CreatedAt   string          `json:"createdAt"`
+	UpdatedAt   string          `json:"updatedAt"`
+	CreatedBy   string          `json:"createdBy"`
+	Tags        []string        `json:"tags"`
+}
+
+// -----------------------------
+// Promotion Stats
+// -----------------------------
+
+type PromotionStats struct {
+	TotalPromotions  int     `json:"totalPromotions"`
+	ActivePromotions int     `json:"activePromotions"`
+	TotalRevenue     float64 `json:"totalRevenue"`
+	TotalOrders      int     `json:"totalOrders"`
+	AverageDiscount  float64 `json:"averageDiscount"`
+}
+
+// -----------------------------
+// Utility: Decode array of rules
+// -----------------------------
+
+func DecodePromotionRules(data []byte) ([]PromotionRule, error) {
+	var rules []PromotionRule
+	if err := json.Unmarshal(data, &rules); err != nil {
+		return nil, err
+	}
+	return rules, nil
+}
+
+// Example helper to inspect conditions programmatically.
+func WalkConditions(conds []Condition, fn func(c Condition) bool) {
+	for _, c := range conds {
+		if !fn(c) {
+			return
+		}
+		if grp, ok := c.(ConditionGroup); ok {
+			WalkConditions(grp.Conditions, fn)
+		}
+	}
+}
+
+type PromotionState struct {
+	Promotions []PromotionRule `json:"promotions"`
+}
+
+type StateFile struct {
+	State   PromotionState `json:"state"`
+	Version int            `json:"version"`
+}
+
+func (sf *StateFile) GetPromotion(id string) (*PromotionRule, bool) {
+	for _, v := range sf.State.Promotions {
+		if v.ID == id {
+			return &v, true
+		}
+	}
+	return nil, false
+}
+
+func LoadStateFile(fileName string) (*StateFile, error) {
+	f, err := os.Open(fileName)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+	dec := json.NewDecoder(f)
+	sf := &StateFile{}
+	err = dec.Decode(sf)
+	if err != nil {
+		return nil, err
+	}
+	return sf, nil
+}

pkg/proxy/remotehost.go

@@ -0,0 +1,212 @@
+package proxy
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"io"
+	"log"
+	"net/http"
+	"time"
+
+	messages "git.tornberg.me/go-cart-actor/pkg/messages"
+	"go.opentelemetry.io/contrib/bridges/otelslog"
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/attribute"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/credentials/insecure"
+)
+
+// RemoteHost mirrors the lightweight controller used for remote node
+// interaction.
+type RemoteHost struct {
+	host          string
+	httpBase      string
+	conn          *grpc.ClientConn
+	transport     *http.Transport
+	client        *http.Client
+	controlClient messages.ControlPlaneClient
+	missedPings   int
+}
+
+const name = "proxy"
+
+var (
+	tracer = otel.Tracer(name)
+	meter  = otel.Meter(name)
+	logger = otelslog.NewLogger(name)
+)
+
+func NewRemoteHost(host string) (*RemoteHost, error) {
+
+	target := fmt.Sprintf("%s:1337", host)
+
+	conn, err := grpc.NewClient(target, grpc.WithTransportCredentials(insecure.NewCredentials()))
+
+	if err != nil {
+		log.Printf("AddRemote: dial %s failed: %v", target, err)
+		return nil, err
+	}
+
+	controlClient := messages.NewControlPlaneClient(conn)
+
+	transport := &http.Transport{
+		MaxIdleConns:        100,
+		MaxIdleConnsPerHost: 100,
+		DisableKeepAlives:   false,
+		IdleConnTimeout:     120 * time.Second,
+	}
+	client := &http.Client{Transport: transport, Timeout: 10 * time.Second}
+
+	return &RemoteHost{
+		host:          host,
+		httpBase:      fmt.Sprintf("http://%s:8080", host),
+		conn:          conn,
+		transport:     transport,
+		client:        client,
+		controlClient: controlClient,
+		missedPings:   0,
+	}, nil
+}
+
+func (h *RemoteHost) Name() string {
+	return h.host
+}
+
+func (h *RemoteHost) Close() error {
+	if h.conn != nil {
+		h.conn.Close()
+	}
+	return nil
+}
+
+func (h *RemoteHost) Ping() bool {
+	var err error = errors.ErrUnsupported
+	for err != nil {
+		ctx, cancel := context.WithTimeout(context.Background(), time.Second)
+		_, err = h.controlClient.Ping(ctx, &messages.Empty{})
+		cancel()
+		if err != nil {
+			h.missedPings++
+			log.Printf("Ping %s failed (%d) %v", h.host, h.missedPings, err)
+		}
+		if !h.IsHealthy() {
+			return false
+		}
+		time.Sleep(time.Millisecond * 200)
+	}
+
+	h.missedPings = 0
+	return true
+}
+
+func (h *RemoteHost) Negotiate(knownHosts []string) ([]string, error) {
+	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+	defer cancel()
+
+	resp, err := h.controlClient.Negotiate(ctx, &messages.NegotiateRequest{
+		KnownHosts: knownHosts,
+	})
+	if err != nil {
+		h.missedPings++
+		log.Printf("Negotiate %s failed: %v", h.host, err)
+		return nil, err
+	}
+	h.missedPings = 0
+	return resp.Hosts, nil
+}
+
+func (h *RemoteHost) GetActorIds() []uint64 {
+	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
+	defer cancel()
+	reply, err := h.controlClient.GetLocalActorIds(ctx, &messages.Empty{})
+	if err != nil {
+		log.Printf("Init remote %s: GetCartIds error: %v", h.host, err)
+		h.missedPings++
+		return []uint64{}
+	}
+	return reply.GetIds()
+}
+
+func (h *RemoteHost) AnnounceOwnership(ownerHost string, uids []uint64) {
+	_, err := h.controlClient.AnnounceOwnership(context.Background(), &messages.OwnershipAnnounce{
+		Host: ownerHost,
+		Ids:  uids,
+	})
+	if err != nil {
+		log.Printf("ownership announce to %s failed: %v", h.host, err)
+		h.missedPings++
+		return
+	}
+	h.missedPings = 0
+}
+
+func (h *RemoteHost) AnnounceExpiry(uids []uint64) {
+	_, err := h.controlClient.AnnounceExpiry(context.Background(), &messages.ExpiryAnnounce{
+		Host: h.host,
+		Ids:  uids,
+	})
+	if err != nil {
+		log.Printf("expiry announce to %s failed: %v", h.host, err)
+		h.missedPings++
+		return
+	}
+	h.missedPings = 0
+}
+
+func (h *RemoteHost) Proxy(id uint64, w http.ResponseWriter, r *http.Request) (bool, error) {
+	target := fmt.Sprintf("%s%s", h.httpBase, r.URL.RequestURI())
+
+	ctx, span := tracer.Start(r.Context(), "remote_proxy")
+	defer span.End()
+	span.SetAttributes(
+		attribute.String("component", "proxy"),
+		attribute.String("cartid", fmt.Sprintf("%d", id)),
+		attribute.String("host", h.host),
+		attribute.String("method", r.Method),
+		attribute.String("target", target),
+	)
+	logger.InfoContext(ctx, "proxying request", "cartid", id, "host", h.host, "method", r.Method)
+
+	req, err := http.NewRequestWithContext(ctx, r.Method, target, r.Body)
+	if err != nil {
+		span.RecordError(err)
+		http.Error(w, "proxy build error", http.StatusBadGateway)
+		return false, err
+	}
+	//r.Body = io.NopCloser(bytes.NewReader(bodyCopy))
+	req.Header.Set("X-Forwarded-Host", r.Host)
+
+	for k, v := range r.Header {
+		for _, vv := range v {
+			req.Header.Add(k, vv)
+		}
+	}
+	res, err := h.client.Do(req)
+	if err != nil {
+		span.RecordError(err)
+		http.Error(w, "proxy request error", http.StatusBadGateway)
+		return false, err
+	}
+	defer res.Body.Close()
+	span.SetAttributes(attribute.Int("status_code", res.StatusCode))
+	for k, v := range res.Header {
+		for _, vv := range v {
+			w.Header().Add(k, vv)
+		}
+	}
+	w.Header().Set("X-Cart-Owner-Routed", "true")
+
+	w.WriteHeader(res.StatusCode)
+	_, copyErr := io.Copy(w, res.Body)
+	if copyErr != nil {
+		span.RecordError(copyErr)
+		return true, copyErr
+	}
+	return true, nil
+
+}
+
+func (r *RemoteHost) IsHealthy() bool {
+	return r.missedPings < 3
+}

pkg/voucher/parser.go

@@ -0,0 +1,343 @@
+package voucher
+
+import (
+	"errors"
+	"fmt"
+	"slices"
+	"strconv"
+	"strings"
+	"unicode"
+)
+
+/*
+Package voucher - rule parser
+
+A lightweight parser for voucher rule expressions.
+
+Supported rule kinds (case-insensitive keywords):
+
+  sku=SKU1|SKU2|SKU3
+    - At least one of the listed SKUs must be present in the cart.
+
+  category=CatA|CatB|CatC
+    - At least one of the listed categories must be present.
+
+  min_total>=12345
+    - Cart total (Inc VAT) must be at least this value (int64).
+
+  min_item_price>=5000
+    - At least one individual item (Inc VAT single unit price) must be at least this value (int64).
+
+Rule list grammar (simplified):
+  rules := rule (sep rule)*
+  rule  := (sku|category) '=' valueList
+         | (min_total|min_item_price) comparator number
+  valueList := value ('|' value)*
+  comparator := '>='   (only comparator currently supported for numeric rules)
+  sep := ';' | ',' | newline
+
+Whitespace is ignored around tokens.
+
+Example:
+  sku=ABC123|XYZ999; category=Shoes|Bags
+  min_total>=10000
+  min_item_price>=2500, category=Accessories
+
+Parsing returns a RuleSet which can later be evaluated against a generic context.
+The evaluation context uses simple Item abstractions to avoid tight coupling with
+the cart implementation (which currently lives under cmd/cart and cannot be
+imported due to being in package main).
+
+This is intentionally conservative and extensible:
+  * Adding new rule kinds: extend RuleKind constants, add parse + evaluate logic.
+  * Supporting new operators: extend numeric rule parsing & evaluation.
+*/
+
+var (
+	// ErrEmptyExpression is returned when the input string has only whitespace.
+	ErrEmptyExpression = errors.New("voucher: empty rule expression")
+	// ErrInvalidRule indicates a syntactic or semantic issue with a single rule fragment.
+	ErrInvalidRule = errors.New("voucher: invalid rule")
+)
+
+// RuleKind enumerates supported rule kinds.
+type RuleKind string
+
+const (
+	RuleSku          RuleKind = "sku"
+	RuleCategory     RuleKind = "category"
+	RuleMinTotal     RuleKind = "min_total"
+	RuleMinItemPrice RuleKind = "min_item_price"
+)
+
+// ruleCondition represents a single, parsed rule.
+type ruleCondition struct {
+	Kind       RuleKind
+	StringVals []string // For sku / category multi-value list
+	MinValue   *int64   // For numeric threshold rules
+	// Operator reserved for future (e.g., >, >=, ==). Currently always ">=" for numeric kinds.
+	Operator string
+}
+
+// RuleSet groups multiple rule conditions (logical AND).
+// All conditions must pass for Applies() to return true.
+type RuleSet struct {
+	Conditions []ruleCondition
+	Source     string // original, trimmed source string
+}
+
+// Item is a minimal abstraction for evaluation (decoupled from cart domain structs).
+type Item struct {
+	Sku       string
+	Category  string
+	UnitPrice int64 // Inc VAT (single unit)
+}
+
+// EvalContext bundles cart-like data necessary for evaluation.
+type EvalContext struct {
+	Items        []Item
+	CartTotalInc int64
+}
+
+// Applies returns true if all rule conditions pass for the context.
+func (rs *RuleSet) Applies(ctx EvalContext) bool {
+	for _, c := range rs.Conditions {
+		switch c.Kind {
+		case RuleSku:
+			if !anyItem(ctx.Items, func(it Item) bool {
+				return containsFold(c.StringVals, it.Sku)
+			}) {
+				return false
+			}
+		case RuleCategory:
+			if !anyItem(ctx.Items, func(it Item) bool {
+				return containsFold(c.StringVals, it.Category)
+			}) {
+				return false
+			}
+		case RuleMinTotal:
+			if c.MinValue == nil || ctx.CartTotalInc < *c.MinValue {
+				return false
+			}
+		case RuleMinItemPrice:
+			if c.MinValue == nil {
+				return false
+			}
+			if !anyItem(ctx.Items, func(it Item) bool {
+				return it.UnitPrice >= *c.MinValue
+			}) {
+				return false
+			}
+		default:
+			// Unknown kinds fail closed to avoid granting unintended discounts.
+			return false
+		}
+	}
+	return true
+}
+
+// anyItem returns true if predicate matches any item.
+func anyItem(items []Item, pred func(Item) bool) bool {
+	return slices.ContainsFunc(items, pred)
+}
+
+// ParseRules parses a rule expression into a RuleSet.
+func ParseRules(input string) (*RuleSet, error) {
+	trimmed := strings.TrimSpace(input)
+	if trimmed == "" {
+		return nil, ErrEmptyExpression
+	}
+
+	fragments := splitRuleFragments(trimmed)
+	if len(fragments) == 0 {
+		return nil, ErrInvalidRule
+	}
+
+	var conditions []ruleCondition
+	for _, frag := range fragments {
+		if frag == "" {
+			continue
+		}
+		c, err := parseFragment(frag)
+		if err != nil {
+			return nil, fmt.Errorf("%w: %s (%v)", ErrInvalidRule, frag, err)
+		}
+		conditions = append(conditions, c)
+	}
+
+	if len(conditions) == 0 {
+		return nil, ErrInvalidRule
+	}
+
+	return &RuleSet{
+		Conditions: conditions,
+		Source:     trimmed,
+	}, nil
+}
+
+// splitRuleFragments splits on ; , or newline, while respecting basic structure.
+func splitRuleFragments(s string) []string {
+	// Normalize line endings
+	s = strings.ReplaceAll(s, "\r\n", "\n")
+
+	// We allow separators: newline, semicolon, comma.
+	seps := func(r rune) bool {
+		return r == ';' || r == '\n' || r == ','
+	}
+	raw := strings.FieldsFunc(s, seps)
+	out := make([]string, 0, len(raw))
+	for _, f := range raw {
+		t := strings.TrimSpace(f)
+		if t != "" {
+			out = append(out, t)
+		}
+	}
+	return out
+}
+
+// parseFragment parses an individual rule fragment.
+func parseFragment(frag string) (ruleCondition, error) {
+	lower := strings.ToLower(frag)
+
+	// Numeric rules have form: <kind> >= number
+	if strings.HasPrefix(lower, string(RuleMinTotal)) ||
+		strings.HasPrefix(lower, string(RuleMinItemPrice)) {
+
+		return parseNumericRule(frag)
+	}
+
+	// Key=Value list rules (sku / category).
+	if i := strings.Index(frag, "="); i > 0 {
+		key := strings.TrimSpace(frag[:i])
+		valPart := strings.TrimSpace(frag[i+1:])
+		if key == "" || valPart == "" {
+			return ruleCondition{}, errors.New("empty key/value")
+		}
+		kind := RuleKind(strings.ToLower(key))
+		switch kind {
+		case RuleSku, RuleCategory:
+			values := splitAndClean(valPart, "|")
+			if len(values) == 0 {
+				return ruleCondition{}, errors.New("empty value list")
+			}
+			return ruleCondition{
+				Kind:       kind,
+				StringVals: values,
+			}, nil
+		default:
+			return ruleCondition{}, fmt.Errorf("unsupported key '%s'", key)
+		}
+	}
+
+	return ruleCondition{}, fmt.Errorf("unrecognized fragment '%s'", frag)
+}
+
+func parseNumericRule(frag string) (ruleCondition, error) {
+	// Support only '>=' for now.
+	var kind RuleKind
+	var rest string
+
+	fragTrim := strings.TrimSpace(frag)
+
+	switch {
+	case strings.HasPrefix(strings.ToLower(fragTrim), string(RuleMinTotal)):
+		kind = RuleMinTotal
+		rest = strings.TrimSpace(fragTrim[len(RuleMinTotal):])
+	case strings.HasPrefix(strings.ToLower(fragTrim), string(RuleMinItemPrice)):
+		kind = RuleMinItemPrice
+		rest = strings.TrimSpace(fragTrim[len(RuleMinItemPrice):])
+	default:
+		return ruleCondition{}, fmt.Errorf("unknown numeric rule '%s'", frag)
+	}
+
+	// Expect operator and number (>= <number>)
+	rest = stripLeadingSpace(rest)
+	if !strings.HasPrefix(rest, ">=") {
+		return ruleCondition{}, fmt.Errorf("expected '>=' in '%s'", frag)
+	}
+	numStr := strings.TrimSpace(rest[2:])
+	if numStr == "" {
+		return ruleCondition{}, fmt.Errorf("missing numeric value in '%s'", frag)
+	}
+
+	value, err := strconv.ParseInt(numStr, 10, 64)
+	if err != nil {
+		return ruleCondition{}, fmt.Errorf("invalid number '%s': %v", numStr, err)
+	}
+	if value < 0 {
+		return ruleCondition{}, fmt.Errorf("negative threshold %d", value)
+	}
+
+	return ruleCondition{
+		Kind:     kind,
+		MinValue: &value,
+		Operator: ">=",
+	}, nil
+}
+
+func stripLeadingSpace(s string) string {
+	for len(s) > 0 && unicode.IsSpace(rune(s[0])) {
+		s = s[1:]
+	}
+	return s
+}
+
+func splitAndClean(s string, sep string) []string {
+	raw := strings.Split(s, sep)
+	out := make([]string, 0, len(raw))
+	for _, r := range raw {
+		t := strings.TrimSpace(r)
+		if t != "" {
+			out = append(out, t)
+		}
+	}
+	return out
+}
+
+func containsFold(list []string, candidate string) bool {
+	for _, v := range list {
+		if strings.EqualFold(v, candidate) {
+			return true
+		}
+	}
+	return false
+}
+
+// Describe returns a human-friendly summary of the parsed rule set.
+func (rs *RuleSet) Describe() string {
+	if rs == nil {
+		return "<nil>"
+	}
+	var parts []string
+	for _, c := range rs.Conditions {
+		switch c.Kind {
+		case RuleSku, RuleCategory:
+			parts = append(parts, fmt.Sprintf("%s in (%s)", c.Kind, strings.Join(c.StringVals, "|")))
+		case RuleMinTotal, RuleMinItemPrice:
+			if c.MinValue != nil {
+				parts = append(parts, fmt.Sprintf("%s %s %d", c.Kind, c.OperatorOr(">="), *c.MinValue))
+			}
+		default:
+			parts = append(parts, fmt.Sprintf("unknown(%s)", c.Kind))
+		}
+	}
+	return strings.Join(parts, " AND ")
+}
+
+func (c ruleCondition) OperatorOr(def string) string {
+	if c.Operator == "" {
+		return def
+	}
+	return c.Operator
+}
+
+// --- Convenience helpers for incremental adoption ---
+
+// MustParseRules panics on parse error (useful in tests or static initialization).
+func MustParseRules(expr string) *RuleSet {
+	rs, err := ParseRules(expr)
+	if err != nil {
+		panic(err)
+	}
+	return rs
+}

pkg/voucher/parser_test.go

@@ -0,0 +1,205 @@
+package voucher
+
+import (
+	"errors"
+	"testing"
+)
+
+func TestParseRules_SimpleSku(t *testing.T) {
+	rs, err := ParseRules("sku=ABC123|XYZ999|def456")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if len(rs.Conditions) != 1 {
+		t.Fatalf("expected 1 condition got %d", len(rs.Conditions))
+	}
+	c := rs.Conditions[0]
+	if c.Kind != RuleSku {
+		t.Fatalf("expected kind sku got %s", c.Kind)
+	}
+	if len(c.StringVals) != 3 {
+		t.Fatalf("expected 3 sku values got %d", len(c.StringVals))
+	}
+	want := []string{"ABC123", "XYZ999", "def456"}
+	for i, v := range want {
+		if c.StringVals[i] != v {
+			t.Fatalf("expected sku[%d]=%s got %s", i, v, c.StringVals[i])
+		}
+	}
+}
+
+func TestRuleCartTotal(t *testing.T) {
+	rs, err := ParseRules("min_total>=500000")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if len(rs.Conditions) != 1 {
+		t.Fatalf("expected 1 condition got %d", len(rs.Conditions))
+	}
+	c := rs.Conditions[0]
+	if c.Kind != RuleMinTotal {
+		t.Fatalf("expected kind cart total got %s", c.Kind)
+	}
+	ctx := EvalContext{
+		Items: []Item{
+			Item{
+				Sku: "123",
+			},
+		},
+		CartTotalInc: 400000,
+	}
+	applied := rs.Applies(ctx)
+	if applied {
+		t.Fatalf("expected")
+	}
+}
+
+func TestParseRules_CategoryAndSkuMixedSeparators(t *testing.T) {
+	rs, err := ParseRules("  category=Shoes|Bags ; sku= A | B , min_total>=1000\nmin_item_price>=500")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if len(rs.Conditions) != 4 {
+		t.Fatalf("expected 4 conditions got %d", len(rs.Conditions))
+	}
+
+	kinds := []RuleKind{RuleCategory, RuleSku, RuleMinTotal, RuleMinItemPrice}
+	for i, k := range kinds {
+		if rs.Conditions[i].Kind != k {
+			t.Fatalf("expected condition[%d] kind %s got %s", i, k, rs.Conditions[i].Kind)
+		}
+	}
+
+	// Validate numeric thresholds
+	if rs.Conditions[2].MinValue == nil || *rs.Conditions[2].MinValue != 1000 {
+		t.Fatalf("expected min_total>=1000 got %+v", rs.Conditions[2])
+	}
+	if rs.Conditions[3].MinValue == nil || *rs.Conditions[3].MinValue != 500 {
+		t.Fatalf("expected min_item_price>=500 got %+v", rs.Conditions[3])
+	}
+}
+
+func TestParseRules_Empty(t *testing.T) {
+	_, err := ParseRules("   \n  ")
+	if !errors.Is(err, ErrEmptyExpression) {
+		t.Fatalf("expected ErrEmptyExpression got %v", err)
+	}
+}
+
+func TestParseRules_Invalid(t *testing.T) {
+	_, err := ParseRules("unknown=foo")
+	if err == nil {
+		t.Fatal("expected error for unknown key")
+	}
+	_, err = ParseRules("min_total>100") // wrong operator
+	if err == nil {
+		t.Fatal("expected error for wrong operator")
+	}
+	_, err = ParseRules("min_total>=") // missing value
+	if err == nil {
+		t.Fatal("expected error for missing numeric value")
+	}
+}
+
+func TestRuleSet_Applies(t *testing.T) {
+	rs := MustParseRules("sku=ABC123|XYZ999; category=Shoes|min_total>=10000; min_item_price>=3000")
+
+	ctx := EvalContext{
+		Items: []Item{
+			{Sku: "ABC123", Category: "Shoes", UnitPrice: 2500},
+			{Sku: "FFF000", Category: "Accessories", UnitPrice: 3200},
+		},
+		CartTotalInc: 12000,
+	}
+
+	if !rs.Applies(ctx) {
+		t.Fatalf("expected rules to apply")
+	}
+
+	// Fail due to missing sku/category
+	ctx2 := EvalContext{
+		Items: []Item{
+			{Sku: "NOPE", Category: "Different", UnitPrice: 4000},
+		},
+		CartTotalInc: 20000,
+	}
+	if rs.Applies(ctx2) {
+		t.Fatalf("expected rules NOT to apply (sku/category mismatch)")
+	}
+
+	// Fail due to min_total
+	ctx3 := EvalContext{
+		Items: []Item{
+			{Sku: "ABC123", Category: "Shoes", UnitPrice: 2500},
+			{Sku: "FFF000", Category: "Accessories", UnitPrice: 3200},
+		},
+		CartTotalInc: 9000,
+	}
+	if rs.Applies(ctx3) {
+		t.Fatalf("expected rules NOT to apply (min_total not reached)")
+	}
+
+	// Fail due to min_item_price (no item >=3000)
+	ctx4 := EvalContext{
+		Items: []Item{
+			{Sku: "ABC123", Category: "Shoes", UnitPrice: 2500},
+			{Sku: "FFF000", Category: "Accessories", UnitPrice: 2800},
+		},
+		CartTotalInc: 15000,
+	}
+	if rs.Applies(ctx4) {
+		t.Fatalf("expected rules NOT to apply (min_item_price not satisfied)")
+	}
+}
+
+func TestRuleSet_Applies_CaseInsensitive(t *testing.T) {
+	rs := MustParseRules("SKU=abc123|xyz999; CATEGORY=Shoes")
+	ctx := EvalContext{
+		Items: []Item{
+			{Sku: "AbC123", Category: "shoes", UnitPrice: 1000},
+		},
+		CartTotalInc: 1000,
+	}
+	if !rs.Applies(ctx) {
+		t.Fatalf("expected rules to apply (case-insensitive match)")
+	}
+}
+
+func TestDescribe(t *testing.T) {
+	rs := MustParseRules("sku=A|B|min_total>=500")
+	desc := rs.Describe()
+	// Loose assertions to avoid over-specification
+	if desc == "" {
+		t.Fatalf("expected non-empty description")
+	}
+	if !(contains(desc, "sku") && contains(desc, "min_total")) {
+		t.Fatalf("description missing expected parts: %s", desc)
+	}
+}
+
+func contains(haystack, needle string) bool {
+	return len(haystack) >= len(needle) && indexOf(haystack, needle) >= 0
+}
+
+// Simple substring search (avoid importing strings to show intent explicitly here)
+func indexOf(s, sub string) int {
+outer:
+	for i := 0; i+len(sub) <= len(s); i++ {
+		for j := 0; j < len(sub); j++ {
+			if s[i+j] != sub[j] {
+				continue outer
+			}
+		}
+		return i
+	}
+	return -1
+}
+
+func TestMustParseRules_Panics(t *testing.T) {
+	defer func() {
+		if r := recover(); r == nil {
+			t.Fatalf("expected panic for invalid expression")
+		}
+	}()
+	MustParseRules("~~ totally invalid ~~")
+}

pkg/voucher/service.go

@@ -0,0 +1,84 @@
+package voucher
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"os"
+
+	"git.tornberg.me/go-cart-actor/pkg/messages"
+)
+
+type Rule struct {
+	Type  string `json:"type"`
+	Value int64  `json:"value"`
+}
+
+type Voucher struct {
+	Code        string `json:"code"`
+	Value       int64  `json:"value"`
+	Rules       string `json:"rules"`
+	Description string `json:"description,omitempty"`
+}
+
+type Service struct {
+	// Add fields here
+}
+
+var ErrInvalidCode = errors.New("invalid vouchercode")
+
+func (s *Service) GetVoucher(code string) (*messages.AddVoucher, error) {
+	if code == "" {
+		return nil, ErrInvalidCode
+	}
+	sf, err := LoadStateFile("data/vouchers.json")
+	if err != nil {
+		return nil, err
+	}
+	v, ok := sf.GetVoucher(code)
+	if !ok {
+		return nil, fmt.Errorf("no voucher found for code: %s", code)
+	}
+
+	return &messages.AddVoucher{
+		Code:        code,
+		Value:       v.Value,
+		Description: v.Description,
+		VoucherRules: []string{
+			v.Rules,
+		},
+	}, nil
+}
+
+type State struct {
+	Vouchers []Voucher `json:"vouchers"`
+}
+
+type StateFile struct {
+	State   State `json:"state"`
+	Version int   `json:"version"`
+}
+
+func (sf *StateFile) GetVoucher(code string) (*Voucher, bool) {
+	for _, v := range sf.State.Vouchers {
+		if v.Code == code {
+			return &v, true
+		}
+	}
+	return nil, false
+}
+
+func LoadStateFile(fileName string) (*StateFile, error) {
+	f, err := os.Open(fileName)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+	dec := json.NewDecoder(f)
+	sf := &StateFile{}
+	err = dec.Decode(sf)
+	if err != nil {
+		return nil, err
+	}
+	return sf, nil
+}

pool-server.go

@@ -1,349 +0,0 @@
-package main
-
-import (
-	"encoding/json"
-	"fmt"
-	"log"
-	"math/rand"
-	"net/http"
-	"strconv"
-	"time"
-
-	messages "git.tornberg.me/go-cart-actor/proto"
-)
-
-type PoolServer struct {
-	pod_name string
-	pool     GrainPool
-}
-
-func NewPoolServer(pool GrainPool, pod_name string) *PoolServer {
-	return &PoolServer{
-		pod_name: pod_name,
-		pool:     pool,
-	}
-}
-
-func (s *PoolServer) HandleGet(w http.ResponseWriter, r *http.Request, id CartId) error {
-	data, err := s.pool.Get(id)
-	if err != nil {
-		return err
-	}
-
-	return s.WriteResult(w, data)
-}
-
-func (s *PoolServer) HandleAddSku(w http.ResponseWriter, r *http.Request, id CartId) error {
-	sku := r.PathValue("sku")
-	data, err := s.pool.Process(id, Message{
-		Type:    AddRequestType,
-		Content: &messages.AddRequest{Sku: sku, Quantity: 1},
-	})
-	if err != nil {
-		return err
-	}
-	return s.WriteResult(w, data)
-}
-
-func ErrorHandler(fn func(w http.ResponseWriter, r *http.Request) error) func(w http.ResponseWriter, r *http.Request) {
-	return func(w http.ResponseWriter, r *http.Request) {
-		err := fn(w, r)
-		if err != nil {
-			log.Printf("Server error, not remote error: %v\n", err)
-			w.WriteHeader(http.StatusInternalServerError)
-			w.Write([]byte(err.Error()))
-		}
-	}
-}
-
-func (s *PoolServer) WriteResult(w http.ResponseWriter, result *FrameWithPayload) error {
-	w.Header().Set("Content-Type", "application/json")
-	w.Header().Set("Cache-Control", "no-cache")
-	w.Header().Set("Access-Control-Allow-Origin", "*")
-	w.Header().Set("X-Pod-Name", s.pod_name)
-	if result.StatusCode != 200 {
-		log.Printf("Call error: %d\n", result.StatusCode)
-		if result.StatusCode >= 200 && result.StatusCode < 600 {
-			w.WriteHeader(int(result.StatusCode))
-		} else {
-			w.WriteHeader(http.StatusInternalServerError)
-		}
-		w.Write([]byte(result.Payload))
-		return nil
-	}
-	w.WriteHeader(http.StatusOK)
-	_, err := w.Write(result.Payload)
-	return err
-}
-
-func (s *PoolServer) HandleDeleteItem(w http.ResponseWriter, r *http.Request, id CartId) error {
-
-	itemIdString := r.PathValue("itemId")
-	itemId, err := strconv.Atoi(itemIdString)
-	if err != nil {
-		return err
-	}
-	data, err := s.pool.Process(id, Message{
-		Type:    RemoveItemType,
-		Content: &messages.RemoveItem{Id: int64(itemId)},
-	})
-	if err != nil {
-		return err
-	}
-	return s.WriteResult(w, data)
-}
-
-type SetDelivery struct {
-	Provider    string                `json:"provider"`
-	Items       []int64               `json:"items"`
-	PickupPoint *messages.PickupPoint `json:"pickupPoint,omitempty"`
-}
-
-func (s *PoolServer) HandleSetDelivery(w http.ResponseWriter, r *http.Request, id CartId) error {
-
-	delivery := SetDelivery{}
-	err := json.NewDecoder(r.Body).Decode(&delivery)
-	if err != nil {
-		return err
-	}
-	data, err := s.pool.Process(id, Message{
-		Type: SetDeliveryType,
-		Content: &messages.SetDelivery{
-			Provider:    delivery.Provider,
-			Items:       delivery.Items,
-			PickupPoint: delivery.PickupPoint,
-		},
-	})
-	if err != nil {
-		return err
-	}
-	return s.WriteResult(w, data)
-}
-
-func (s *PoolServer) HandleSetPickupPoint(w http.ResponseWriter, r *http.Request, id CartId) error {
-
-	deliveryIdString := r.PathValue("deliveryId")
-	deliveryId, err := strconv.Atoi(deliveryIdString)
-	if err != nil {
-		return err
-	}
-	pickupPoint := messages.PickupPoint{}
-	err = json.NewDecoder(r.Body).Decode(&pickupPoint)
-	if err != nil {
-		return err
-	}
-	reply, err := s.pool.Process(id, Message{
-		Type: SetPickupPointType,
-		Content: &messages.SetPickupPoint{
-			DeliveryId: int64(deliveryId),
-			Id:         pickupPoint.Id,
-			Name:       pickupPoint.Name,
-			Address:    pickupPoint.Address,
-			City:       pickupPoint.City,
-			Zip:        pickupPoint.Zip,
-			Country:    pickupPoint.Country,
-		},
-	})
-	if err != nil {
-		return err
-	}
-	return s.WriteResult(w, reply)
-}
-
-func (s *PoolServer) HandleRemoveDelivery(w http.ResponseWriter, r *http.Request, id CartId) error {
-
-	deliveryIdString := r.PathValue("deliveryId")
-	deliveryId, err := strconv.Atoi(deliveryIdString)
-	if err != nil {
-		return err
-	}
-	reply, err := s.pool.Process(id, Message{
-		Type:    RemoveDeliveryType,
-		Content: &messages.RemoveDelivery{Id: int64(deliveryId)},
-	})
-	if err != nil {
-		return err
-	}
-	return s.WriteResult(w, reply)
-}
-
-func (s *PoolServer) HandleQuantityChange(w http.ResponseWriter, r *http.Request, id CartId) error {
-	changeQuantity := messages.ChangeQuantity{}
-	err := json.NewDecoder(r.Body).Decode(&changeQuantity)
-	if err != nil {
-		return err
-	}
-	reply, err := s.pool.Process(id, Message{
-		Type:    ChangeQuantityType,
-		Content: &changeQuantity,
-	})
-	if err != nil {
-		return err
-	}
-	return s.WriteResult(w, reply)
-}
-
-func (s *PoolServer) HandleSetCartItems(w http.ResponseWriter, r *http.Request, id CartId) error {
-	setCartItems := messages.SetCartRequest{}
-	err := json.NewDecoder(r.Body).Decode(&setCartItems)
-	if err != nil {
-		return err
-	}
-	reply, err := s.pool.Process(id, Message{
-		Type:    SetCartItemsType,
-		Content: &setCartItems,
-	})
-	if err != nil {
-		return err
-	}
-	return s.WriteResult(w, reply)
-}
-
-func (s *PoolServer) HandleAddRequest(w http.ResponseWriter, r *http.Request, id CartId) error {
-	addRequest := messages.AddRequest{}
-	err := json.NewDecoder(r.Body).Decode(&addRequest)
-	if err != nil {
-		return err
-	}
-	reply, err := s.pool.Process(id, Message{
-		Type:    AddRequestType,
-		Content: &addRequest,
-	})
-	if err != nil {
-		return err
-	}
-	return s.WriteResult(w, reply)
-}
-
-func (s *PoolServer) HandleConfirmation(w http.ResponseWriter, r *http.Request, id CartId) error {
-	orderId := r.PathValue("orderId")
-	if orderId == "" {
-		return fmt.Errorf("orderId is empty")
-	}
-	order, err := KlarnaInstance.GetOrder(orderId)
-
-	if err != nil {
-		return err
-	}
-
-	w.Header().Set("Content-Type", "application/json")
-	w.Header().Set("X-Pod-Name", s.pod_name)
-	w.Header().Set("Cache-Control", "no-cache")
-	w.Header().Set("Access-Control-Allow-Origin", "*")
-	w.WriteHeader(http.StatusOK)
-	return json.NewEncoder(w).Encode(order)
-}
-
-func (s *PoolServer) HandleCheckout(w http.ResponseWriter, r *http.Request, id CartId) error {
-
-	reply, err := s.pool.Process(id, Message{
-		Type: CreateCheckoutOrderType,
-		Content: &messages.CreateCheckoutOrder{
-			Terms:        "https://slask-finder.tornberg.me/terms",
-			Checkout:     "https://slask-finder.tornberg.me/checkout?order_id={checkout.order.id}",
-			Confirmation: "https://slask-finder.tornberg.me/confirmation/{checkout.order.id}",
-			Push:         "https://cart.tornberg.me/push?order_id={checkout.order.id}",
-		},
-	})
-	if err != nil {
-		return err
-	}
-	if reply.StatusCode != 200 {
-		return s.WriteResult(w, reply)
-	}
-
-	// w.Header().Set("Content-Type", "application/json")
-	// w.Header().Set("X-Pod-Name", s.pod_name)
-	// w.Header().Set("Cache-Control", "no-cache")
-	// w.Header().Set("Access-Control-Allow-Origin", "*")
-	// w.WriteHeader(http.StatusOK)
-
-	return s.WriteResult(w, reply)
-}
-
-func NewCartId() CartId {
-	id := time.Now().UnixNano() + rand.Int63()
-
-	return ToCartId(fmt.Sprintf("%d", id))
-}
-
-func CookieCartIdHandler(fn func(w http.ResponseWriter, r *http.Request, cartId CartId) error) func(w http.ResponseWriter, r *http.Request) error {
-	return func(w http.ResponseWriter, r *http.Request) error {
-		var cartId CartId
-		cartIdCookie := r.CookiesNamed("cartid")
-		if cartIdCookie == nil || len(cartIdCookie) == 0 {
-			cartId = NewCartId()
-			http.SetCookie(w, &http.Cookie{
-				Name:     "cartid",
-				Value:    cartId.String(),
-				Secure:   true,
-				HttpOnly: true,
-				Path:     "/",
-				Expires:  time.Now().AddDate(0, 0, 14),
-				SameSite: http.SameSiteLaxMode,
-			})
-		} else {
-			cartId = ToCartId(cartIdCookie[0].Value)
-		}
-		return fn(w, r, cartId)
-	}
-}
-
-func (s *PoolServer) RemoveCartCookie(w http.ResponseWriter, r *http.Request, cartId CartId) error {
-	cartId = NewCartId()
-	http.SetCookie(w, &http.Cookie{
-		Name:     "cartid",
-		Value:    cartId.String(),
-		Path:     "/",
-		Secure:   true,
-		HttpOnly: true,
-		Expires:  time.Unix(0, 0),
-		SameSite: http.SameSiteLaxMode,
-	})
-	w.WriteHeader(http.StatusOK)
-	return nil
-}
-
-func CartIdHandler(fn func(w http.ResponseWriter, r *http.Request, cartId CartId) error) func(w http.ResponseWriter, r *http.Request) error {
-	return func(w http.ResponseWriter, r *http.Request) error {
-		cartId := ToCartId(r.PathValue("id"))
-		return fn(w, r, cartId)
-	}
-}
-
-func (s *PoolServer) Serve() *http.ServeMux {
-	mux := http.NewServeMux()
-	//mux.HandleFunc("/", s.RewritePath)
-	mux.HandleFunc("OPTIONS /", func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("Access-Control-Allow-Origin", "*")
-		w.Header().Set("Access-Control-Allow-Methods", "GET, PUT, POST, DELETE")
-		w.Header().Set("Access-Control-Allow-Headers", "Content-Type")
-		w.WriteHeader(http.StatusOK)
-	})
-
-	mux.HandleFunc("GET /", ErrorHandler(CookieCartIdHandler(s.HandleGet)))
-	mux.HandleFunc("GET /add/{sku}", ErrorHandler(CookieCartIdHandler(s.HandleAddSku)))
-	mux.HandleFunc("POST /", ErrorHandler(CookieCartIdHandler(s.HandleAddRequest)))
-	mux.HandleFunc("POST /set", ErrorHandler(CookieCartIdHandler(s.HandleSetCartItems)))
-	mux.HandleFunc("DELETE /{itemId}", ErrorHandler(CookieCartIdHandler(s.HandleDeleteItem)))
-	mux.HandleFunc("PUT /", ErrorHandler(CookieCartIdHandler(s.HandleQuantityChange)))
-	mux.HandleFunc("DELETE /", ErrorHandler(CookieCartIdHandler(s.RemoveCartCookie)))
-	mux.HandleFunc("POST /delivery", ErrorHandler(CookieCartIdHandler(s.HandleSetDelivery)))
-	mux.HandleFunc("DELETE /delivery/{deliveryId}", ErrorHandler(CookieCartIdHandler(s.HandleRemoveDelivery)))
-	mux.HandleFunc("PUT /delivery/{deliveryId}/pickupPoint", ErrorHandler(CookieCartIdHandler(s.HandleSetPickupPoint)))
-	mux.HandleFunc("GET /checkout", ErrorHandler(CookieCartIdHandler(s.HandleCheckout)))
-	mux.HandleFunc("GET /confirmation/{orderId}", ErrorHandler(CookieCartIdHandler(s.HandleConfirmation)))
-
-	mux.HandleFunc("GET /byid/{id}", ErrorHandler(CartIdHandler(s.HandleGet)))
-	mux.HandleFunc("GET /byid/{id}/add/{sku}", ErrorHandler(CartIdHandler(s.HandleAddSku)))
-	mux.HandleFunc("POST /byid/{id}", ErrorHandler(CartIdHandler(s.HandleAddRequest)))
-	mux.HandleFunc("DELETE /byid/{id}/{itemId}", ErrorHandler(CartIdHandler(s.HandleDeleteItem)))
-	mux.HandleFunc("PUT /byid/{id}", ErrorHandler(CartIdHandler(s.HandleQuantityChange)))
-	mux.HandleFunc("POST /byid/{id}/delivery", ErrorHandler(CartIdHandler(s.HandleSetDelivery)))
-	mux.HandleFunc("DELETE /byid/{id}/delivery/{deliveryId}", ErrorHandler(CartIdHandler(s.HandleRemoveDelivery)))
-	mux.HandleFunc("PUT /byid/{id}/delivery/{deliveryId}/pickupPoint", ErrorHandler(CartIdHandler(s.HandleSetPickupPoint)))
-	mux.HandleFunc("GET /byid/{id}/checkout", ErrorHandler(CartIdHandler(s.HandleCheckout)))
-	mux.HandleFunc("GET /byid/{id}/confirmation", ErrorHandler(CartIdHandler(s.HandleConfirmation)))
-
-	return mux
-}