Merge branch 'main' of git-ssh.tornberg.me:mats/go-cart-actor into refactor/http-proxy

Co-authored-by: matst80 <mats.tornberg@gmail.com>
Reviewed-on: https://git.tornberg.me/mats/go-cart-actor/pulls/4
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 +1,77 @@
 name: Build and Publish
-run-name: ${{ gitea.actor }} is building 🚀
+run-name: ${{ gitea.actor }} build 🚀
 on: [push]
 
 jobs:
+  Metadata:
+    runs-on: arm64
+    outputs:
+      version: ${{ steps.meta.outputs.version }}
+      git_commit: ${{ steps.meta.outputs.git_commit }}
+      build_date: ${{ steps.meta.outputs.build_date }}
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+      - id: meta
+        name: Derive build metadata
+        run: |
+          GIT_COMMIT=$(git rev-parse HEAD)
+          if git describe --tags --exact-match >/dev/null 2>&1; then
+            VERSION=$(git describe --tags --exact-match)
+          else
+            VERSION=$(git rev-parse --short=12 HEAD)
+          fi
+          BUILD_DATE=$(date -u +"%Y-%m-%dT%H:%M:%SZ")
+          echo "git_commit=$GIT_COMMIT" >> $GITHUB_OUTPUT
+          echo "version=$VERSION" >> $GITHUB_OUTPUT
+          echo "build_date=$BUILD_DATE" >> $GITHUB_OUTPUT
+
   BuildAndDeployAmd64:
+    needs: Metadata
     runs-on: amd64
     steps:
-      - name: Check out repository code
+      - uses: actions/checkout@v4
-        uses: actions/checkout@v4
+      - name: Build amd64 image
-      - name: Build docker image
+        run: |
-        run: docker build --progress=plain -t registry.knatofs.se/go-cart-actor-amd64:latest .
+          docker build \
-      - name: Push to registry
+            --build-arg VERSION=${{ needs.Metadata.outputs.version }} \
-        run: docker push registry.knatofs.se/go-cart-actor-amd64:latest
+            --build-arg GIT_COMMIT=${{ needs.Metadata.outputs.git_commit }} \
-      - name: Deploy to Kubernetes
+            --build-arg BUILD_DATE=${{ needs.Metadata.outputs.build_date }} \
+            --progress=plain \
+            -t registry.knatofs.se/go-cart-actor-amd64:latest \
+            -t registry.knatofs.se/go-cart-actor-amd64:${{ needs.Metadata.outputs.version }} \
+            .
+      - name: Push amd64 images
+        run: |
+          docker push registry.knatofs.se/go-cart-actor-amd64:latest
+          docker push registry.knatofs.se/go-cart-actor-amd64:${{ needs.Metadata.outputs.version }}
+      - name: Apply deployment manifests
         run: kubectl apply -f deployment/deployment.yaml -n cart
-      - name: Rollout amd64 deployment
+      - name: Rollout amd64 deployment (pin to version)
-        run: kubectl rollout restart deployment/cart-actor-x86 -n cart
+        run: |
+          kubectl set image deployment/cart-actor-x86 -n cart cart-actor-amd64=registry.knatofs.se/go-cart-actor-amd64:${{ needs.Metadata.outputs.version }}
+          kubectl rollout status deployment/cart-actor-x86 -n cart
 
-  BuildAndDeploy:
+  BuildAndDeployArm64:
+    needs: Metadata
     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
+            --build-arg VERSION=${{ needs.Metadata.outputs.version }} \
-        run: docker push registry.knatofs.se/go-cart-actor
+            --build-arg GIT_COMMIT=${{ needs.Metadata.outputs.git_commit }} \
-      - name: Rollout arm64 deployment
+            --build-arg BUILD_DATE=${{ needs.Metadata.outputs.build_date }} \
-        run: kubectl rollout restart deployment/cart-actor-arm64 -n cart
+            --progress=plain \
+            -t registry.knatofs.se/go-cart-actor:latest \
+            -t registry.knatofs.se/go-cart-actor:${{ needs.Metadata.outputs.version }} \
+            .
+      - name: Push arm64 images
+        run: |
+          docker push registry.knatofs.se/go-cart-actor:latest
+          docker push registry.knatofs.se/go-cart-actor:${{ needs.Metadata.outputs.version }}
+      - name: Rollout arm64 deployment (pin to version)
+        run: |
+          kubectl set image deployment/cart-actor-arm64 -n cart cart-actor-arm64=registry.knatofs.se/go-cart-actor:${{ needs.Metadata.outputs.version }}
+          kubectl rollout status deployment/cart-actor-arm64 -n cart

Dockerfile

@@ -1,17 +1,75 @@
-# 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
+
+############################
+# 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
+
+# Document (not expose forcibly) typical ports: 8080 (HTTP), 1337 (gRPC)
+EXPOSE 8080 1337
+
+USER nonroot:nonroot
 ENTRYPOINT ["/go-cart-actor"]

GRPC-MIGRATION-PLAN.md

@@ -1,396 +0,0 @@
-# gRPC Migration Plan
-
-File: GRPC-MIGRATION-PLAN.md  
-Author: (Generated plan)  
-Status: Draft for review  
-Target Release: Next major version (breaking change – no mixed compatibility)
-
----
-
-## 1. Overview
-
-This document describes the full migration of the current custom TCP frame-based protocol (both the cart mutation/state channel on port `1337` and the control plane on port `1338`) to gRPC. We will remove all legacy packet framing (`FrameWithPayload`, `RemoteGrain`, `GenericListener` handlers for these two ports) and replace them with two gRPC services:
-
-1. Cart Actor Service (mutations + state retrieval)
-2. Control Plane Service (cluster membership, negotiation, ownership change, lifecycle)
-
-We intentionally keep:
-- Internal `CartGrain` logic, message storage format, disk persistence, and JSON cart serialization.
-- Existing message type numeric mapping for backward compatibility with persisted event logs.
-- HTTP/REST API layer unchanged (it still consumes JSON state from the local/remote grain pipeline).
-
-We do NOT implement mixed-version compatibility; migration occurs atomically (cluster restart with new image).
-
----
-
-## 2. Goals
-
-- Remove custom binary frame protocol & simplify maintenance.
-- Provide clearer, strongly defined interfaces via `.proto` schemas.
-- Improve observability via gRPC interceptors (metrics & tracing hooks).
-- Reduce per-call overhead compared with the current manual connection pooling + handwritten framing (HTTP/2 multiplexing + connection reuse).
-- Prepare groundwork for future enhancements (streaming, typed state, event streaming) without rewriting again.
-
----
-
-## 3. Non-Goals (Phase 1)
-
-- Converting the cart state payload from JSON to a strongly typed proto.
-- Introducing authentication / mTLS (may be added later).
-- Changing persistence or replay format.
-- Changing the HTTP API contract.
-- Implementing streaming watchers or push updates.
-
----
-
-## 4. Architecture After Migration
-
-Ports:  
-- `:1337` → gRPC CartActor service.  
-- `:1338` → gRPC ControlPlane service.
-
-Each node:
-- Runs one gRPC server with both services (can use a single listener bound to two services or keep two separate listeners; we will keep two ports initially to minimize operational surprise, but they could be merged later).
-- Maintains a connection pool of `*grpc.ClientConn` objects keyed by remote hostname (one per remote host, reused for both services).
-
-Call Flow (Mutation):
-1. HTTP request hits `PoolServer`.
-2. `SyncedPool.getGrain(cartId)`:
-   - Local: direct invocation.
-   - Remote: uses `RemoteGrainGRPC` (new) which invokes `CartActor.Mutate`.
-3. Response JSON returned unchanged.
-
-Control Plane Flow:
-- Discovery (K8s watch) still triggers `AddRemote(host)`.
-- Instead of custom `Ping`, `Negotiate`, etc. via frames, call gRPC methods on `ControlPlane` service.
-- Ownership changes use `ConfirmOwner` RPC.
-
----
-
-## 5. Proto Design
-
-### 5.1 Cart Actor Proto (Envelope Pattern)
-
-We keep an envelope with `bytes payload` holding the serialized underlying cart mutation proto (existing types in `messages.proto`). This minimizes churn.
-
-Indented code block (proto sketch):
-
-    syntax = "proto3";
-    package cart;
-    option go_package = "git.tornberg.me/go-cart-actor/proto;proto";
-
-    enum MutationType {
-      MUTATION_TYPE_UNSPECIFIED = 0;
-      MUTATION_ADD_REQUEST = 1;
-      MUTATION_ADD_ITEM = 2;
-      MUTATION_REMOVE_ITEM = 4;
-      MUTATION_REMOVE_DELIVERY = 5;
-      MUTATION_CHANGE_QUANTITY = 6;
-      MUTATION_SET_DELIVERY = 7;
-      MUTATION_SET_PICKUP_POINT = 8;
-      MUTATION_CREATE_CHECKOUT_ORDER = 9;
-      MUTATION_SET_CART_ITEMS = 10;
-      MUTATION_ORDER_COMPLETED = 11;
-    }
-
-    message MutationRequest {
-      string cart_id = 1;
-      MutationType type = 2;
-      bytes payload = 3;          // Serialized specific mutation proto
-      int64 client_timestamp = 4; // Optional; server fills if zero
-    }
-
-    message MutationReply {
-      int32 status_code = 1;
-      bytes payload = 2; // JSON cart state or error string
-    }
-
-    message StateRequest {
-      string cart_id = 1;
-    }
-
-    message StateReply {
-      int32 status_code = 1;
-      bytes payload = 2; // JSON cart state
-    }
-
-    service CartActor {
-      rpc Mutate(MutationRequest) returns (MutationReply);
-      rpc GetState(StateRequest) returns (StateReply);
-    }
-
-### 5.2 Control Plane Proto
-
-    syntax = "proto3";
-    package control;
-    option go_package = "git.tornberg.me/go-cart-actor/proto;proto";
-
-    message Empty {}
-
-    message PingReply {
-      string host = 1;
-      int64 unix_time = 2;
-    }
-
-    message NegotiateRequest {
-      repeated string known_hosts = 1;
-    }
-    message NegotiateReply {
-      repeated string hosts = 1; // Healthy hosts returned
-    }
-
-    message CartIdsReply {
-      repeated string cart_ids = 1;
-    }
-
-    message OwnerChangeRequest {
-      string cart_id = 1;
-      string new_host = 2;
-    }
-    message OwnerChangeAck {
-      bool accepted = 1;
-      string message = 2;
-    }
-
-    message ClosingNotice {
-      string host = 1;
-    }
-
-    service ControlPlane {
-      rpc Ping(Empty) returns (PingReply);
-      rpc Negotiate(NegotiateRequest) returns (NegotiateReply);
-      rpc GetCartIds(Empty) returns (CartIdsReply);
-      rpc ConfirmOwner(OwnerChangeRequest) returns (OwnerChangeAck);
-      rpc Closing(ClosingNotice) returns (OwnerChangeAck);
-    }
-
----
-
-## 6. Message Type Mapping
-
-| Legacy Constant | Numeric | New Enum Value              |
-|-----------------|---------|-----------------------------|
-| AddRequestType  | 1       | MUTATION_ADD_REQUEST        |
-| AddItemType     | 2       | MUTATION_ADD_ITEM           |
-| RemoveItemType  | 4       | MUTATION_REMOVE_ITEM        |
-| RemoveDeliveryType | 5    | MUTATION_REMOVE_DELIVERY    |
-| ChangeQuantityType | 6    | MUTATION_CHANGE_QUANTITY    |
-| SetDeliveryType | 7       | MUTATION_SET_DELIVERY       |
-| SetPickupPointType | 8    | MUTATION_SET_PICKUP_POINT   |
-| CreateCheckoutOrderType | 9 | MUTATION_CREATE_CHECKOUT_ORDER |
-| SetCartItemsType | 10     | MUTATION_SET_CART_ITEMS     |
-| OrderCompletedType | 11   | MUTATION_ORDER_COMPLETED    |
-
-Persisted events keep original numeric codes; reconstruction simply casts to `MutationType`.
-
----
-
-## 7. Components To Remove / Replace
-
-Remove (after migration complete):
-- `remote-grain.go`
-- `rpc-server.go`
-- Any packet/frame-specific types solely used by the above (search: `FrameWithPayload`, `RemoteHandleMutation`, `RemoteGetState` where not reused by disk or internal logic).
-- The constants representing network frame types in `synced-pool.go` (RemoteNegotiate, AckChange, etc.) replaced by gRPC calls.
-- netpool usage for remote cart channel (control plane also no longer needs `Connection` abstraction).
-
-Retain (until reworked or optionally cleaned later):
-- `message.go` (for persistence)
-- `message-handler.go`
-- `cart-grain.go`
-- `messages.proto` (underlying mutation messages)
-- HTTP API server and REST handlers.
-
----
-
-## 8. New / Modified Components
-
-New files (planned):
-- `proto/cart_actor.proto`
-- `proto/control_plane.proto`
-- `grpc/cart_actor_server.go` (server impl)
-- `grpc/cart_actor_client.go` (client adapter implementing `Grain`)
-- `grpc/control_plane_server.go`
-- `grpc/control_plane_client.go`
-- `grpc/interceptors.go` (metrics, logging, optional tracing hooks)
-- `remote_grain_grpc.go` (adapter bridging existing interfaces)
-- `control_plane_adapter.go` (replaces frame handlers in `SyncedPool`)
-
-Modified:
-- `synced-pool.go` (remote host management now uses gRPC clients; negotiation logic updated)
-- `main.go` (initialize both gRPC services on startup)
-- `go.mod` (add `google.golang.org/grpc`)
-
----
-
-## 9. Step-by-Step Migration Plan
-
-1. Add proto files and generate Go code (`protoc --go_out --go-grpc_out`).
-2. Implement `CartActorServer`:
-   - Translate `MutationRequest` to `Message`.
-   - Use existing handler registry for payload encode/decode.
-   - Return JSON cart state.
-3. Implement `CartActorClient` wrapper (`RemoteGrainGRPC`) implementing:
-   - `HandleMessage`: Build envelope, call `Mutate`.
-   - `GetCurrentState`: Call `GetState`.
-4. Implement `ControlPlaneServer` with methods:
-   - `Ping`: returns host + time.
-   - `Negotiate`: merge host lists; emulate old logic.
-   - `GetCartIds`: iterate local grains.
-   - `ConfirmOwner`: replicate quorum flow (accept always; error path for future).
-   - `Closing`: schedule remote removal.
-5. Implement `ControlPlaneClient` used inside `SyncedPool.AddRemote`.
-6. Refactor `SyncedPool`:
-   - Replace frame handlers registration with gRPC client calls.
-   - Replace `Server.AddHandler(...)` start-up with launching gRPC server.
-   - Implement periodic health checks using `Ping`.
-7. Remove old connection constructs for 1337/1338.
-8. Metrics:
-   - Add unary interceptor capturing duration and status.
-   - Replace packet counters with `cart_grpc_mutate_calls_total`, `cart_grpc_control_calls_total`, histograms for latency.
-9. Update `main.go` to start:
-   - gRPC server(s).
-   - HTTP server as before.
-10. Delete legacy files & update README build instructions.
-11. Load testing & profiling on Raspberry Pi hardware (or ARM emulation).
-12. Final cleanup & dead code removal (search for now-unused constants & structs).
-13. Tag release.
-
----
-
-## 10. Performance Considerations (Raspberry Pi Focus)
-
-- Single `*grpc.ClientConn` per remote host (HTTP/2 multiplexing) to reduce file descriptor and handshake overhead.
-- Use small keepalive pings (optional) only if connections drop; default may suffice.
-- Avoid reflection / dynamic dispatch in hot path: pre-build a mapping from `MutationType` to handler function.
-- Reuse byte buffers:
-  - Implement a `sync.Pool` for mutation serialization to reduce GC pressure.
-- Enforce per-RPC deadlines (e.g. 300–400ms) to avoid pile-ups.
-- Backpressure:
-  - Before dispatch: if local grain pool at capacity and target grain is remote, abort early with 503 to caller (optional).
-- Disable gRPC compression for small payloads (mutation messages are small). Condition compression if payload > threshold (e.g. 8KB).
-- Compile with `-ldflags="-s -w"` in production to reduce binary size (optional).
-- Enable `GOMAXPROCS` tuned to CPU cores; Pi often benefits from leaving default but monitor.
-- Use histograms with limited buckets to reduce Prometheus cardinality.
-
----
-
-## 11. Testing Strategy
-
-Unit:
-- Message type mapping tests (legacy -> enum).
-- Envelope roundtrip: Original proto -> payload -> gRPC -> server decode -> internal Message.
-
-Integration:
-- Two-node cluster simulation:
-  - Mutate cart on Node A, ownership moves, verify remote access from Node B.
-  - Quorum failure simulation (temporarily reject `ConfirmOwner`).
-- Control plane negotiation: start nodes in staggered order, assert final membership.
-
-Load/Perf:
-- Benchmark local mutation vs remote mutation latency.
-- High concurrency test (N goroutines each performing X mutations).
-- Memory profiling (ensure no large buffer retention).
-
-Failure Injection:
-- Kill a node mid-mutation; client call should timeout and not corrupt local state.
-- Simulated network partition: drop `Ping` replies; ensure host removal path triggers.
-
----
-
-## 12. Rollback Strategy
-
-Because no mixed-version compatibility is provided, rollback = redeploy previous version containing legacy protocol:
-1. Stop all new-version pods.
-2. Deploy old version cluster-wide.
-3. No data migration needed (event persistence unaffected).
-
-Note: Avoid partial upgrades; perform full rolling restart quickly to prevent split-brain (new nodes won’t talk to old nodes).
-
----
-
-## 13. Risks & Mitigations
-
-| Risk | Description | Mitigation |
-|------|-------------|------------|
-| Full-cluster restart required | No mixed compatibility | Schedule maintenance window |
-| gRPC adds CPU overhead | Envelope + marshaling cost | Buffer reuse, keep small messages uncompressed |
-| Ownership race | Timing differences after refactor | Add explicit logs + tests around `RequestOwnership` path |
-| Hidden dependency on frame-level status codes | Some code may assume `FrameWithPayload` fields | Wrap gRPC responses into minimal compatibility structs until fully removed |
-| Memory growth | Connection reuse & pooled buffers not implemented initially | Add `sync.Pool` & track memory via pprof early |
-
----
-
-## 14. Logging & Observability
-
-- Structured log entries for:
-  - Ownership changes
-  - Negotiation rounds
-  - Remote spawn events
-  - Mutation failures (with cart id, mutation type)
-- Metrics:
-  - `cart_grpc_mutate_duration_seconds` (histogram)
-  - `cart_grpc_mutate_errors_total`
-  - `cart_grpc_control_duration_seconds`
-  - `cart_remote_hosts` (gauge)
-  - Retain existing grain counts.
-- Optional future: OpenTelemetry tracing (span per remote mutation).
-
----
-
-## 15. Future Enhancements (Post-Migration)
-
-- Replace JSON state with `CartState` proto and provide streaming watch API.
-- mTLS between nodes (certificate rotation via K8s Secret or SPIRE).
-- Distributed tracing integration.
-- Ownership leasing with TTL and optimistic renewal.
-- Delta replication or CRDT-based conflict resolution for experimentation.
-
----
-
-## 16. Task Breakdown & Estimates
-
-| Task | Estimate |
-|------|----------|
-| Proto definitions & generation | 0.5d |
-| CartActor server/client | 1.0d |
-| ControlPlane server/client | 1.0d |
-| SyncedPool refactor | 1.0d |
-| Metrics & interceptors | 0.5d |
-| Remove legacy code & cleanup | 0.5d |
-| Tests (unit + integration) | 1.5d |
-| Benchmark & tuning | 0.5–1.0d |
-| Total | ~6–7d |
-
----
-
-## 17. Open Questions (Confirm Before Implementation)
-
-1. Combine both services on a single port (simplify ops) or keep dual-port first? (Default here: keep dual, but easy to merge.)
-2. Minimum Go version remains 1.24.x—acceptable to add `google.golang.org/grpc` latest?
-3. Accept adding `sync.Pool` micro-optimizations in first pass or postpone?
-
----
-
-## 18. Acceptance Criteria
-
-- All previous integration tests (adjusted to gRPC) pass.
-- Cart operations (add, remove, delivery, checkout) function across at least a 2‑node cluster.
-- Control plane negotiation forms consistent host list.
-- Latency for a remote mutation does not degrade beyond an acceptable threshold (define baseline before merge).
-- Legacy networking code fully removed.
-
----
-
-## 19. Next Steps (If Approved)
-
-1. Implement proto files and commit.
-2. Scaffold server & client code.
-3. Refactor `SyncedPool` and `main.go`.
-4. Add metrics and tests.
-5. Run benchmark on target Pi hardware.
-6. Review & merge.
-
----
-
-End of Plan.

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

@@ -1,5 +1,36 @@
 # Go Cart Actor
 
+## Migration Notes (Ring-based Ownership Transition)
+
+This release removes the legacy ConfirmOwner ownership negotiation RPC in favor of deterministic ownership via the consistent hashing ring.
+
+Summary of changes:
+- ConfirmOwner RPC removed from the ControlPlane service.
+- OwnerChangeRequest message removed (was only used by ConfirmOwner).
+- OwnerChangeAck retained solely as the response type for the Closing RPC.
+- SyncedPool now relies exclusively on the ring for ownership (no quorum negotiation).
+- Remote proxy creation includes a bounded readiness retry to reduce first-call failures.
+- New Prometheus ring metrics: 
+  - cart_ring_epoch
+  - cart_ring_hosts
+  - cart_ring_vnodes
+  - cart_ring_host_share{host}
+  - cart_ring_lookup_local_total
+  - cart_ring_lookup_remote_total
+
+Action required for consumers:
+1. Regenerate protobuf code after pulling (requires protoc-gen-go and protoc-gen-go-grpc installed).
+2. Remove any client code or automation invoking ConfirmOwner (calls will now return UNIMPLEMENTED if using stale generated stubs).
+3. Update monitoring/alerts that referenced ConfirmOwner or ownership quorum failures—use ring metrics instead.
+4. If you previously interpreted “ownership flapping” via ConfirmOwner logs, now check for:
+   - Rapid changes in ring epoch (cart_ring_epoch)
+   - Host churn (cart_ring_hosts)
+   - Imbalance in vnode distribution (cart_ring_host_share)
+
+No data migration is necessary; cart IDs and grain state are unaffected.
+
+---
+
 A distributed cart management system using the actor model pattern.
 
 ## Prerequisites
@@ -176,3 +207,238 @@ curl --cookie cookies.txt http://localhost:8080/cart/add/TEST-SKU-123
 - 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`)
+
+---
+
+## 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

@@ -1,621 +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
-
-// String returns the cart id as a trimmed UTF-8 string (trailing zero bytes removed).
-func (id CartId) String() string {
-	n := 0
-	for n < len(id) && id[n] != 0 {
-		n++
-	}
-	return string(id[:n])
-}
-
-// ToCartId converts an arbitrary string to a fixed-size CartId (truncating or padding with zeros).
-func ToCartId(s string) CartId {
-	var id CartId
-	copy(id[:], []byte(s))
-	return id
-}
-
-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 float64, ok bool) (int, error) {
-	if !ok {
-		return 0, fmt.Errorf("invalid type")
-	}
-	return int(data), nil
-}
-
-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.GetNumberFieldValue(5)) // getInt(item.Fields[5])
-
-	price, priceErr := getInt(item.GetNumberFieldValue(4)) //Fields[4]
-
-	if priceErr != nil {
-		return nil, fmt.Errorf("invalid price")
-	}
-
-	stock := InStock
-	/*item.t
-	if item.StockLevel == "0" || item.StockLevel == "" {
-		stock = OutOfStock
-	} else if item.StockLevel == "5+" {
-		stock = LowStock
-		}*/
-	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:      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)
-	}
-
-}

cmd/backoffice/main.go

@@ -0,0 +1,5 @@
+package main
+
+func main() {
+	// Your code here
+}

cmd/cart/amqp-order-handler.go

@@ -0,0 +1,61 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	amqp "github.com/rabbitmq/amqp091-go"
+)
+
+type AmqpOrderHandler struct {
+	Url        string
+	Connection *amqp.Connection
+	Channel    *amqp.Channel
+}
+
+func (h *AmqpOrderHandler) Connect() error {
+	conn, err := amqp.Dial(h.Url)
+	if err != nil {
+		return fmt.Errorf("failed to connect to RabbitMQ: %w", err)
+	}
+	h.Connection = conn
+
+	ch, err := conn.Channel()
+	if err != nil {
+		return fmt.Errorf("failed to open a channel: %w", err)
+	}
+	h.Channel = ch
+
+	return nil
+}
+
+func (h *AmqpOrderHandler) Close() error {
+	if h.Channel != nil {
+		h.Channel.Close()
+	}
+	if h.Connection != nil {
+		return h.Connection.Close()
+	}
+	return nil
+}
+
+func (h *AmqpOrderHandler) OrderCompleted(body []byte) error {
+	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+	defer cancel()
+
+	err := h.Channel.PublishWithContext(ctx,
+		"orders", // exchange
+		"new",    // routing key
+		false,    // mandatory
+		false,    // immediate
+		amqp.Publishing{
+			ContentType: "application/json",
+			Body:        body,
+		})
+	if err != nil {
+		return fmt.Errorf("failed to publish a message: %w", err)
+	}
+
+	return nil
+}

cmd/cart/cart-grain.go

@@ -0,0 +1,268 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"slices"
+	"sync"
+	"time"
+
+	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"`
+	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"`
+}
+
+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 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
+	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"`
+}
+
+type Voucher struct {
+	Code  string                  `json:"code"`
+	Rules []*messages.VoucherRule `json:"rules"`
+	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 _, rule := range v.Rules {
+		expr := rule.GetCondition()
+		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 (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
+}
+
+func getInt(data float64, ok bool) (int, error) {
+	if !ok {
+		return 0, fmt.Errorf("invalid type")
+	}
+	return int(data), nil
+}
+
+// func (c *CartGrain) AddItem(sku string, qty int, country string, storeId *string) (*CartGrain, error) {
+// 	cartItem, err := getItemData(sku, qty, country)
+// 	if err != nil {
+// 		return nil, err
+// 	}
+// 	cartItem.StoreId = storeId
+// 	return c.Apply(cartItem, false)
+// }
+
+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))
+
+		item.TotalPrice = *rowTotal
+
+		c.TotalPrice.Add(*rowTotal)
+
+		if item.OrgPrice != nil {
+			diff := NewPrice()
+			diff.Add(*item.OrgPrice)
+			diff.Subtract(item.Price)
+			if diff.IncVat > 0 {
+				c.TotalDiscount.Add(*diff)
+			}
+		}
+
+	}
+	for _, delivery := range c.Deliveries {
+		c.TotalPrice.Add(delivery.Price)
+	}
+	for _, voucher := range c.Vouchers {
+		if _, ok := voucher.AppliesTo(c); ok {
+			value := NewPriceFromIncVat(voucher.Value, 25)
+
+			c.TotalDiscount.Add(*value)
+			c.TotalPrice.Subtract(*value)
+		}
+	}
+}

cmd/cart/cart_grain_totals_test.go

@@ -0,0 +1,48 @@
+package main
+
+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 != 250 {
+		t.Fatalf("TotalDiscount expected 250 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)
+	}
+}

cmd/cart/cart_id.go

@@ -0,0 +1,159 @@
+package main
+
+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
+}

cmd/cart/cart_id_test.go

@@ -0,0 +1,185 @@
+package main
+
+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
+}

cmd/cart/checkout_builder.go

@@ -0,0 +1,119 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+)
+
+// 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
+	Validation   string
+	Push         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 *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:        2500, // 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,
+			Validation:   meta.Validation,
+			Push:         meta.Push,
+		},
+	}
+
+	payload, err := json.Marshal(order)
+	if err != nil {
+		return nil, nil, fmt.Errorf("marshal checkout order: %w", err)
+	}
+
+	return payload, order, nil
+}

cmd/cart/main.go

@@ -12,10 +12,15 @@ import (
 	"syscall"
 	"time"
 
-	messages "git.tornberg.me/go-cart-actor/proto"
+	"git.tornberg.me/go-cart-actor/pkg/actor"
+	"git.tornberg.me/go-cart-actor/pkg/discovery"
+	messages "git.tornberg.me/go-cart-actor/pkg/messages"
+	"git.tornberg.me/go-cart-actor/pkg/proxy"
+	"git.tornberg.me/go-cart-actor/pkg/voucher"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promauto"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
+	"k8s.io/apimachinery/pkg/watch"
 	"k8s.io/client-go/kubernetes"
 	"k8s.io/client-go/rest"
 )
@@ -35,84 +40,17 @@ var (
 	})
 )
 
-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
+	pool *actor.SimpleGrainPool[CartGrain]
-	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">
@@ -132,70 +70,159 @@ func getCountryFromHost(host string) string {
 	if strings.Contains(strings.ToLower(host), "-no") {
 		return "no"
 	}
+	if strings.Contains(strings.ToLower(host), "-se") {
 		return "se"
 	}
-
+	return ""
-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{
+func GetDiscovery() discovery.Discovery {
-		Terms:        fmt.Sprintf("%s/terms", baseUrl),
+	if podIp == "" {
-		Checkout:     fmt.Sprintf("%s/checkout?order_id={checkout.order.id}", baseUrl),
+		return nil
-		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,
 	}
+
+	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)
+}
+
+type MutationContext struct {
+	VoucherService voucher.Service
 }
 
 func main() {
 
-	storage, err := NewDiskStorage(fmt.Sprintf("data/%s_state.gob", name))
+	controlPlaneConfig := actor.DefaultServerConfig()
+
+	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{}
+		}),
+	)
+	diskStorage := actor.NewDiskStorage[CartGrain]("data", reg)
+	poolConfig := actor.GrainPoolConfig[CartGrain]{
+		MutationRegistry: reg,
+		Storage:          diskStorage,
+		Spawn: func(id uint64) (actor.Grain[CartGrain], error) {
+			grainSpawns.Inc()
+			ret := &CartGrain{
+				lastItemId:     0,
+				lastDeliveryId: 0,
+				Deliveries:     []*CartDelivery{},
+				Id:             CartId(id),
+				Items:          []*CartItem{},
+				TotalPrice:     NewPrice(),
+			}
+			// Set baseline lastChange at spawn; replay may update it to last event timestamp.
+			ret.lastChange = time.Now()
+			ret.lastAccess = time.Now()
+
+			err := diskStorage.LoadEvents(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.Printf("Error loading state: %v\n", err)
+		log.Fatalf("Error creating cart pool: %v\n", err)
 	}
 	app := &App{
-		pool:    NewGrainLocalPool(65535, 5*time.Minute, spawn),
+		pool: pool,
-		storage: storage,
 	}
 
-	syncedPool, err := NewSyncedPool(app.pool, podIp, GetDiscovery())
+	grpcSrv, err := actor.NewControlServer[*CartGrain](controlPlaneConfig, pool)
 	if err != nil {
-		log.Fatalf("Error creating synced pool: %v\n", err)
+		log.Fatalf("Error starting control plane gRPC server: %v\n", err)
-	}
-
-	// Start unified gRPC server (CartActor + ControlPlane) replacing legacy RPC server on :1337
-	// TODO: Remove any remaining legacy RPC server references and deprecated frame-based code after full gRPC migration is validated.
-	grpcSrv, err := StartGRPCServer(":1337", app.pool, syncedPool)
-	if err != nil {
-		log.Fatalf("Error starting gRPC server: %v\n", err)
 	}
 	defer grpcSrv.GracefulStop()
 
-	go func() {
+	go diskStorage.SaveLoop(10 * time.Second)
-		for range time.Tick(time.Minute * 10) {
+
-			err := app.Save()
+	go func(hw discovery.Discovery) {
+		if hw == nil {
+			log.Print("No discovery service available")
+			return
+		}
+		ch, err := hw.Watch()
 		if err != nil {
-				log.Printf("Error saving: %v\n", err)
+			log.Printf("Discovery error: %v", err)
+			return
+		}
+		for evt := range ch {
+			if evt.Host == "" {
+				continue
+			}
+			switch evt.Type {
+			case watch.Deleted:
+				if pool.IsKnown(evt.Host) {
+					pool.RemoveHost(evt.Host)
+				}
+			default:
+				if !pool.IsKnown(evt.Host) {
+					log.Printf("Discovered host %s", evt.Host)
+					pool.AddRemote(evt.Host)
 				}
 			}
-	}()
+		}
+	}(GetDiscovery())
+
 	orderHandler := &AmqpOrderHandler{
 		Url: amqpUrl,
 	}
+	klarnaClient := NewKlarnaClient(KlarnaPlaygroundUrl, os.Getenv("KLARNA_API_USERNAME"), os.Getenv("KLARNA_API_PASSWORD"))
 
-	syncedServer := NewPoolServer(syncedPool, fmt.Sprintf("%s, %s", name, podIp))
+	syncedServer := NewPoolServer(pool, fmt.Sprintf("%s, %s", name, podIp), klarnaClient)
 	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) {
+	mux.HandleFunc("GET /add/remote/{host}", func(w http.ResponseWriter, r *http.Request) {
-	// 	syncedPool.AddRemote(r.PathValue("host"))
+		pool.AddRemote(r.PathValue("host"))
-	// })
+	})
 	// mux.HandleFunc("GET /save", app.HandleSave)
 	//mux.HandleFunc("/", app.RewritePath)
 	mux.HandleFunc("/debug/pprof/", pprof.Index)
@@ -206,16 +233,13 @@ func main() {
 	mux.Handle("/metrics", promhttp.Handler())
 	mux.HandleFunc("/healthz", func(w http.ResponseWriter, r *http.Request) {
 		// Grain pool health: simple capacity check (mirrors previous GrainHandler.IsHealthy)
-		app.pool.mu.RLock()
+		grainCount, capacity := app.pool.LocalUsage()
-		grainCount := len(app.pool.grains)
-		capacity := app.pool.PoolSize
-		app.pool.mu.RUnlock()
 		if grainCount >= capacity {
 			w.WriteHeader(http.StatusInternalServerError)
 			w.Write([]byte("grain pool at capacity"))
 			return
 		}
-		if !syncedPool.IsHealthy() {
+		if !pool.IsHealthy() {
 			w.WriteHeader(http.StatusInternalServerError)
 			w.Write([]byte("control plane not healthy"))
 			return
@@ -248,39 +272,49 @@ func main() {
 				w.Write([]byte("no cart id to checkout is empty"))
 				return
 			}
-			cartId := ToCartId(cookie.Value)
+			parsed, ok := ParseCartId(cookie.Value)
-			reply, err := syncedServer.pool.Process(cartId, Message{
+			if !ok {
-				Type:    CreateCheckoutOrderType,
+				w.WriteHeader(http.StatusBadRequest)
-				Content: getCheckoutOrder(r.Host, cartId),
+				w.Write([]byte("invalid cart id format"))
-			})
-			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
 			}
+			cartId := parsed
+			syncedServer.ProxyHandler(func(w http.ResponseWriter, r *http.Request, cartId CartId) error {
+				order, err = syncedServer.CreateOrUpdateCheckout(r.Host, cartId)
+				if err != nil {
+					return err
+				}
+				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)
+				fmt.Fprintf(w, tpl, order.HTMLSnippet)
+				return nil
+			})(cartId, w, r)
+
+			if err != nil {
+				w.WriteHeader(http.StatusInternalServerError)
+				w.Write([]byte(err.Error()))
+			}
+
+			// v2: Apply now returns *CartGrain; order creation handled inside grain (no payload to unmarshal)
 		} else {
-			prevOrder, err := KlarnaInstance.GetOrder(orderId)
+			order, err = klarnaClient.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)))
+			fmt.Fprintf(w, 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)
+		order, err := klarnaClient.GetOrder(orderId)
 
 		if err != nil {
 			w.WriteHeader(http.StatusInternalServerError)
@@ -302,7 +336,7 @@ func main() {
 		}
 
 		w.WriteHeader(http.StatusOK)
-		w.Write([]byte(fmt.Sprintf(tpl, order.HTMLSnippet)))
+		fmt.Fprintf(w, tpl, order.HTMLSnippet)
 	})
 	mux.HandleFunc("/validate", func(w http.ResponseWriter, r *http.Request) {
 		log.Printf("Klarna order validation, method: %s", r.Method)
@@ -340,7 +374,7 @@ func main() {
 		orderId := r.URL.Query().Get("order_id")
 		log.Printf("Order confirmation push: %s", orderId)
 
-		order, err := KlarnaInstance.GetOrder(orderId)
+		order, err := klarnaClient.GetOrder(orderId)
 
 		if err != nil {
 			log.Printf("Error creating request: %v\n", err)
@@ -355,13 +389,13 @@ func main() {
 			return
 		}
 
-		err = triggerOrderCompleted(err, syncedServer, order)
+		err = triggerOrderCompleted(syncedServer, order)
 		if err != nil {
 			log.Printf("Error processing cart message: %v\n", err)
 			w.WriteHeader(http.StatusInternalServerError)
 			return
 		}
-		err = KlarnaInstance.AcknowledgeOrder(orderId)
+		err = klarnaClient.AcknowledgeOrder(orderId)
 		if err != nil {
 			log.Printf("Error acknowledging order: %v\n", err)
 		}
@@ -373,6 +407,8 @@ func main() {
 		w.Write([]byte("1.0.0"))
 	})
 
+	mux.HandleFunc("/openapi.json", ServeEmbeddedOpenAPI)
+
 	sigs := make(chan os.Signal, 1)
 	done := make(chan bool, 1)
 	signal.Notify(sigs, syscall.SIGTERM)
@@ -380,8 +416,9 @@ func main() {
 	go func() {
 		sig := <-sigs
 		fmt.Println("Shutting down due to signal:", sig)
-		go syncedPool.Close()
+		diskStorage.Close()
-		app.Save()
+		pool.Close()
+
 		done <- true
 	}()
 
@@ -391,15 +428,18 @@ func main() {
 
 }
 
-func triggerOrderCompleted(err error, syncedServer *PoolServer, order *CheckoutOrder) error {
+func triggerOrderCompleted(syncedServer *PoolServer, order *CheckoutOrder) error {
-	_, err = syncedServer.pool.Process(ToCartId(order.MerchantReference1), Message{
+	mutation := &messages.OrderCreated{
-		Type: OrderCompletedType,
-		Content: &messages.OrderCreated{
 		OrderId: order.ID,
 		Status:  order.Status,
-		},
+	}
-	})
+	cid, ok := ParseCartId(order.MerchantReference1)
-	return err
+	if !ok {
+		return fmt.Errorf("invalid cart id in order reference: %s", order.MerchantReference1)
+	}
+	_, applyErr := syncedServer.Apply(uint64(cid), mutation)
+
+	return applyErr
 }
 
 func confirmOrder(order *CheckoutOrder, orderHandler *AmqpOrderHandler) error {

cmd/cart/mutation_add_item.go

@@ -0,0 +1,91 @@
+package main
+
+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)
+	}
+
+	// Fast path: merge with existing item having same SKU
+	if existing, found := g.FindItemWithSku(m.Sku); found {
+		if existing.StoreId == m.StoreId {
+			existing.Quantity += int(m.Quantity)
+			existing.Stock = StockStatus(m.Stock)
+			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,
+		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,
+		},
+
+		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)
+}

cmd/cart/mutation_add_voucher.go

@@ -0,0 +1,64 @@
+package main
+
+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,
+		Code:  m.Code,
+		Rules: m.VoucherRules,
+		Value: m.Value,
+	})
+	g.UpdateTotals()
+	return nil
+}

cmd/cart/mutation_change_quantity.go

@@ -0,0 +1,54 @@
+package main
+
+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:]...)
+		return nil
+	}
+
+	g.Items[foundIndex].Quantity = int(m.Quantity)
+	g.UpdateTotals()
+	return nil
+}

cmd/cart/mutation_initialize_checkout.go

@@ -0,0 +1,44 @@
+package main
+
+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
+}

cmd/cart/mutation_order_created.go

@@ -0,0 +1,48 @@
+package main
+
+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
+}

cmd/cart/mutation_remove_delivery.go

@@ -0,0 +1,49 @@
+package main
+
+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
+}

cmd/cart/mutation_remove_item.go

@@ -0,0 +1,45 @@
+package main
+
+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
+}

cmd/cart/mutation_set_delivery.go

@@ -0,0 +1,96 @@
+package main
+
+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
+}

cmd/cart/mutation_set_pickup_point.go

@@ -0,0 +1,62 @@
+package main
+
+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
+}

cmd/cart/openapi.json

@@ -0,0 +1,677 @@
+{
+  "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": { "$ref": "#/components/schemas/CartGrain" }
+              }
+            }
+          },
+          "400": { "description": "Invalid body" },
+          "500": { "description": "Server error" }
+        }
+      }
+    },
+    "/cart/byid/{id}": {
+      "get": {
+        "summary": "Get cart by explicit id",
+        "parameters": [{ "$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" }
+        }
+      }
+    },
+    "/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]+$",
+          "minLength": 1
+        }
+      },
+      "DeliveryIdParam": {
+        "name": "deliveryId",
+        "in": "path",
+        "required": true,
+        "schema": { "type": "integer", "format": "int64", "minimum": 0 }
+      }
+    },
+    "schemas": {
+      "CartGrain": {
+        "type": "object",
+        "description": "Cart aggregate (actor state)",
+        "properties": {
+          "id": {
+            "type": "string",
+            "description": "Cart id (base62 encoded uint64)"
+          },
+          "items": {
+            "type": "array",
+            "items": { "$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" }
+        },
+        "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"]
+      }
+    }
+  },
+  "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/pool-server.go

@@ -0,0 +1,532 @@
+package main
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"log"
+	"net/http"
+	"strconv"
+	"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"
+	"github.com/gogo/protobuf/proto"
+)
+
+type PoolServer struct {
+	actor.GrainPool[*CartGrain]
+	pod_name     string
+	klarnaClient *KlarnaClient
+}
+
+func NewPoolServer(pool actor.GrainPool[*CartGrain], pod_name string, klarnaClient *KlarnaClient) *PoolServer {
+	return &PoolServer{
+		GrainPool:    pool,
+		pod_name:     pod_name,
+		klarnaClient: klarnaClient,
+	}
+}
+
+func (s *PoolServer) ApplyLocal(id CartId, mutation ...proto.Message) (*actor.MutationResult[*CartGrain], error) {
+	return s.Apply(uint64(id), mutation...)
+}
+
+func (s *PoolServer) GetCartHandler(w http.ResponseWriter, r *http.Request, id CartId) error {
+	grain, err := s.Get(uint64(id))
+	if err != nil {
+		return err
+	}
+
+	return s.WriteResult(w, grain)
+}
+
+func (s *PoolServer) AddSkuToCartHandler(w http.ResponseWriter, r *http.Request, id CartId) error {
+	sku := r.PathValue("sku")
+	msg, err := GetItemAddMessage(sku, 1, getCountryFromHost(r.Host), nil)
+	if err != nil {
+		return err
+	}
+	data, err := s.ApplyLocal(id, msg)
+	if err != nil {
+		return err
+	}
+	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 CartId) error {
+
+	itemIdString := r.PathValue("itemId")
+	itemId, err := strconv.ParseInt(itemIdString, 10, 64)
+	if err != nil {
+		return err
+	}
+	data, err := s.ApplyLocal(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 CartId) error {
+
+	delivery := SetDeliveryRequest{}
+	err := json.NewDecoder(r.Body).Decode(&delivery)
+	if err != nil {
+		return err
+	}
+	data, err := s.ApplyLocal(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 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(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 CartId) error {
+
+	deliveryIdString := r.PathValue("deliveryId")
+	deliveryId, err := strconv.Atoi(deliveryIdString)
+	if err != nil {
+		return err
+	}
+	reply, err := s.ApplyLocal(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 CartId) error {
+	changeQuantity := messages.ChangeQuantity{}
+	err := json.NewDecoder(r.Body).Decode(&changeQuantity)
+	if err != nil {
+		return err
+	}
+	reply, err := s.ApplyLocal(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(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(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 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(setCartItems.Items, setCartItems.Country)...)
+
+	reply, err := s.ApplyLocal(id, msgs...)
+	if err != nil {
+		return err
+	}
+	return s.WriteResult(w, reply)
+}
+
+func (s *PoolServer) AddMultipleItemHandler(w http.ResponseWriter, r *http.Request, id CartId) error {
+	setCartItems := SetCartItems{}
+	err := json.NewDecoder(r.Body).Decode(&setCartItems)
+	if err != nil {
+		return err
+	}
+
+	reply, err := s.ApplyLocal(id, getMultipleAddMessages(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 CartId) error {
+	addRequest := AddRequest{Quantity: 1}
+	err := json.NewDecoder(r.Body).Decode(&addRequest)
+	if err != nil {
+		return err
+	}
+	msg, err := GetItemAddMessage(addRequest.Sku, int(addRequest.Quantity), addRequest.Country, addRequest.StoreId)
+	if err != nil {
+		return err
+	}
+	reply, err := s.ApplyLocal(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 (s *PoolServer) CreateOrUpdateCheckout(host string, id CartId) (*CheckoutOrder, error) {
+	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),
+		Validation:   fmt.Sprintf("https://%s/validate", host),
+		Push:         fmt.Sprintf("https://%s/push?order_id={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(uint64(id))
+	if err != nil {
+		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(grain.OrderReference, bytes.NewReader(payload))
+	} else {
+		return s.klarnaClient.CreateOrder(bytes.NewReader(payload))
+	}
+}
+
+func (s *PoolServer) ApplyCheckoutStarted(klarnaOrder *CheckoutOrder, id CartId) (*actor.MutationResult[*CartGrain], error) {
+	// Persist initialization state via mutation (best-effort)
+	return s.ApplyLocal(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 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 CartId
+		cookie, err := r.Cookie("cartid")
+		if err != nil || cookie.Value == "" {
+			id = 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 := ParseCartId(cookie.Value)
+			if !ok {
+				id = 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 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 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 CartId
+		raw := r.PathValue("id")
+		// If no id supplied, generate a new one
+		if raw == "" {
+			id := MustNewCartId()
+			w.Header().Set("Set-Cart-Id", id.String())
+		} else {
+			// Parse base62 cart id
+			if parsedId, ok := 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 CartId) error) func(cartId CartId, w http.ResponseWriter, r *http.Request) error {
+	return func(cartId CartId, w http.ResponseWriter, r *http.Request) error {
+		if ownerHost, ok := s.OwnerHost(uint64(cartId)); ok {
+			handled, err := ownerHost.Proxy(uint64(cartId), w, r)
+			if err == nil && handled {
+				return nil
+			}
+		}
+
+		return fn(w, r, cartId)
+
+	}
+}
+
+type AddVoucherRequest struct {
+	VoucherCode string `json:"code"`
+}
+
+func (s *PoolServer) AddVoucherHandler(w http.ResponseWriter, r *http.Request, cartId CartId) error {
+	data := &AddVoucherRequest{}
+	json.NewDecoder(r.Body).Decode(data)
+	v := voucher.Service{}
+	msg, err := v.GetVoucher(data.VoucherCode)
+	if err != nil {
+		w.WriteHeader(http.StatusInternalServerError)
+		w.Write([]byte(err.Error()))
+		return err
+	}
+	reply, err := s.ApplyLocal(cartId, msg)
+	if err != nil {
+		w.WriteHeader(http.StatusInternalServerError)
+		w.Write([]byte(err.Error()))
+		return err
+	}
+	s.WriteResult(w, reply)
+	return nil
+}
+
+func (s *PoolServer) RemoveVoucherHandler(w http.ResponseWriter, r *http.Request, cartId 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(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() *http.ServeMux {
+
+	mux := http.NewServeMux()
+	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 /", CookieCartIdHandler(s.ProxyHandler(s.GetCartHandler)))
+	mux.HandleFunc("GET /add/{sku}", CookieCartIdHandler(s.ProxyHandler(s.AddSkuToCartHandler)))
+	mux.HandleFunc("POST /add", CookieCartIdHandler(s.ProxyHandler(s.AddMultipleItemHandler)))
+	mux.HandleFunc("POST /", CookieCartIdHandler(s.ProxyHandler(s.AddSkuRequestHandler)))
+	mux.HandleFunc("POST /set", CookieCartIdHandler(s.ProxyHandler(s.SetCartItemsHandler)))
+	mux.HandleFunc("DELETE /{itemId}", CookieCartIdHandler(s.ProxyHandler(s.DeleteItemHandler)))
+	mux.HandleFunc("PUT /", CookieCartIdHandler(s.ProxyHandler(s.QuantityChangeHandler)))
+	mux.HandleFunc("DELETE /", CookieCartIdHandler(s.ProxyHandler(s.RemoveCartCookie)))
+	mux.HandleFunc("POST /delivery", CookieCartIdHandler(s.ProxyHandler(s.SetDeliveryHandler)))
+	mux.HandleFunc("DELETE /delivery/{deliveryId}", CookieCartIdHandler(s.ProxyHandler(s.RemoveDeliveryHandler)))
+	mux.HandleFunc("PUT /delivery/{deliveryId}/pickupPoint", CookieCartIdHandler(s.ProxyHandler(s.SetPickupPointHandler)))
+	mux.HandleFunc("PUT /voucher", CookieCartIdHandler(s.ProxyHandler(s.AddVoucherHandler)))
+	mux.HandleFunc("DELETE /voucher/{voucherId}", CookieCartIdHandler(s.ProxyHandler(s.RemoveVoucherHandler)))
+
+	//mux.HandleFunc("GET /checkout", CookieCartIdHandler(s.ProxyHandler(s.HandleCheckout)))
+	//mux.HandleFunc("GET /confirmation/{orderId}", CookieCartIdHandler(s.ProxyHandler(s.HandleConfirmation)))
+
+	mux.HandleFunc("GET /byid/{id}", CartIdHandler(s.ProxyHandler(s.GetCartHandler)))
+	mux.HandleFunc("GET /byid/{id}/add/{sku}", CartIdHandler(s.ProxyHandler(s.AddSkuToCartHandler)))
+	mux.HandleFunc("POST /byid/{id}", CartIdHandler(s.ProxyHandler(s.AddSkuRequestHandler)))
+	mux.HandleFunc("DELETE /byid/{id}/{itemId}", CartIdHandler(s.ProxyHandler(s.DeleteItemHandler)))
+	mux.HandleFunc("PUT /byid/{id}", CartIdHandler(s.ProxyHandler(s.QuantityChangeHandler)))
+	mux.HandleFunc("POST /byid/{id}/delivery", CartIdHandler(s.ProxyHandler(s.SetDeliveryHandler)))
+	mux.HandleFunc("DELETE /byid/{id}/delivery/{deliveryId}", CartIdHandler(s.ProxyHandler(s.RemoveDeliveryHandler)))
+	mux.HandleFunc("PUT /byid/{id}/delivery/{deliveryId}/pickupPoint", CartIdHandler(s.ProxyHandler(s.SetPickupPointHandler)))
+	mux.HandleFunc("PUT /byid/{id}/voucher", CookieCartIdHandler(s.ProxyHandler(s.AddVoucherHandler)))
+	mux.HandleFunc("DELETE /byid/{id}/voucher/{voucherId}", CookieCartIdHandler(s.ProxyHandler(s.RemoveVoucherHandler)))
+	//mux.HandleFunc("GET /byid/{id}/checkout", CartIdHandler(s.ProxyHandler(s.HandleCheckout)))
+	//mux.HandleFunc("GET /byid/{id}/confirmation", CartIdHandler(s.ProxyHandler(s.HandleConfirmation)))
+
+	return mux
+}

cmd/cart/price.go

@@ -0,0 +1,131 @@
+package main
+
+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
+}

cmd/cart/price_test.go

@@ -0,0 +1,135 @@
+package main
+
+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(1000, 0.25)
+	if p.IncVat != 1000 {
+		t.Fatalf("expected IncVat %d got %d", 1000, p.IncVat)
+	}
+	if p.VatRates[25] != 250 {
+		t.Fatalf("expected VAT 25 rate %d got %d", 250, p.VatRates[25])
+	}
+	if p.ValueExVat() != 750 {
+		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())
+	}
+}

cmd/cart/product-fetcher.go

@@ -0,0 +1,121 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"strconv"
+	"strings"
+
+	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(sku string, country string) (*index.DataItem, error) {
+	baseUrl := getBaseUrl(country)
+	res, err := http.Get(fmt.Sprintf("%s/api/by-sku/%s", baseUrl, sku))
+	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(sku string, qty int, country string, storeId *string) (*messages.AddItem, error) {
+	item, err := FetchItem(sku, country)
+	if err != nil {
+		return nil, err
+	}
+	return ToItemAddMessage(item, storeId, qty, country), nil
+}
+
+func ToItemAddMessage(item *index.DataItem, storeId *string, qty int, country string) *messages.AddItem {
+	orgPrice, _ := getInt(item.GetNumberFieldValue(5)) // getInt(item.Fields[5])
+
+	price, err := getInt(item.GetNumberFieldValue(4)) //Fields[4]
+	if err != nil {
+		return nil
+	}
+
+	stock := StockStatus(0)
+	centralStockValue, ok := item.GetStringFieldValue(3)
+	if storeId == nil {
+		if ok {
+			pureNumber := strings.Replace(centralStockValue, "+", "", -1)
+			if centralStock, err := strconv.ParseInt(pureNumber, 10, 64); err == nil {
+				stock = StockStatus(centralStock)
+			}
+		}
+	} else {
+		storeStock, ok := item.Stock.GetStock()[*storeId]
+		if ok {
+			stock = 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,
+	}
+}
+
+func getTax(articleType string) int32 {
+	switch articleType {
+	case "ZDIE":
+		return 600
+	default:
+		return 2500
+	}
+}

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

@@ -15,7 +15,7 @@ metadata:
     arch: amd64
   name: cart-actor-x86
 spec:
-  replicas: 0
+  replicas: 3
   selector:
     matchLabels:
       app: cart-actor
@@ -55,12 +55,8 @@ spec:
           ports:
             - containerPort: 8080
               name: web
-            - containerPort: 1234
-              name: echo
             - containerPort: 1337
               name: rpc
-            - containerPort: 1338
-              name: quorum
           livenessProbe:
             httpGet:
               path: /livez
@@ -161,12 +157,8 @@ spec:
           ports:
             - containerPort: 8080
               name: web
-            - containerPort: 1234
-              name: echo
             - containerPort: 1337
               name: rpc
-            - containerPort: 1338
-              name: quorum
           livenessProbe:
             httpGet:
               path: /livez
@@ -217,18 +209,6 @@ 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:
@@ -248,10 +228,10 @@ 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

deployment/scaling.yaml

@@ -1,4 +1,4 @@
-apiVersion: autoscaling/v1
+apiVersion: autoscaling/v2
 kind: HorizontalPodAutoscaler
 metadata:
     name: cart-scaler-amd
@@ -9,9 +9,47 @@ spec:
         name: cart-actor-x86
     minReplicas: 3
     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
@@ -22,4 +60,42 @@ spec:
         name: cart-actor-arm64
     minReplicas: 3
     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

@@ -1,84 +0,0 @@
-package main
-
-import (
-	"fmt"
-	"log"
-	"net"
-	"sync"
-	"time"
-)
-
-type DiscardedHost struct {
-	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++
-		if host.Tries >= 5 {
-			// Exceeded retry threshold; will be dropped by run loop.
-		}
-	} 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,
-	})
-}

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
-}

frames.go

@@ -1,102 +0,0 @@
-package main
-
-// Minimal frame abstractions retained after removal of the legacy TCP/frame
-// networking layer. These types remain only to avoid a wide cascading refactor
-// across existing grain / pool logic that still constructs and passes
-// FrameWithPayload objects internally.
-//
-// The original responsibilities this replaces:
-//   - Binary framing, checksums, network IO
-//   - Distinction between request / reply frame types
-//
-// What remains:
-//   - A light weight container (FrameWithPayload) used as an in‑process
-//     envelope for status code + typed marker + payload bytes (JSON or proto).
-//   - Message / status constants referenced in existing code paths.
-//
-// Recommended future cleanup (post‑migration):
-//   - Remove FrameType entirely and replace with enumerated semantic results
-//     or error values.
-//   - Replace FrameWithPayload with a struct { Status int; Data []byte }.
-//   - Remove remote_* reply type branching once all callers rely on gRPC
-//     status + strongly typed responses.
-//
-// For now we keep this minimal surface to keep the gRPC migration focused.
-
-type (
-	// FrameType is a symbolic identifier carried through existing code paths.
-	// No ordering or bit semantics are required anymore.
-	FrameType  uint32
-	StatusCode uint32
-)
-
-type Frame struct {
-	Type       FrameType
-	StatusCode StatusCode
-	Length     uint32
-	// Checksum retained for compatibility; no longer validated.
-	Checksum uint32
-}
-
-// FrameWithPayload wraps a Frame with an opaque payload.
-// Payload usually contains JSON encoded cart state or an error message.
-type FrameWithPayload struct {
-	Frame
-	Payload []byte
-}
-
-// -----------------------------------------------------------------------------
-// Legacy Frame Type Constants (minimal subset still referenced)
-// -----------------------------------------------------------------------------
-const (
-	RemoteGetState            = FrameType(0x01)
-	RemoteHandleMutation      = FrameType(0x02)
-	ResponseBody              = FrameType(0x03) // (rarely used; kept for completeness)
-	RemoteGetStateReply       = FrameType(0x04)
-	RemoteHandleMutationReply = FrameType(0x05)
-	RemoteCreateOrderReply    = FrameType(0x06)
-)
-
-// MakeFrameWithPayload constructs an in‑process frame wrapper.
-// Length & Checksum are filled for backward compatibility (no validation logic
-// depends on the checksum anymore).
-func MakeFrameWithPayload(msg FrameType, statusCode StatusCode, payload []byte) FrameWithPayload {
-	length := uint32(len(payload))
-	return FrameWithPayload{
-		Frame: Frame{
-			Type:       msg,
-			StatusCode: statusCode,
-			Length:     length,
-			Checksum:   (uint32(msg) + uint32(statusCode) + length) / 8, // simple legacy formula
-		},
-		Payload: payload,
-	}
-}
-
-// Clone creates a shallow copy of the frame, duplicating the payload slice.
-func (f *FrameWithPayload) Clone() *FrameWithPayload {
-	if f == nil {
-		return nil
-	}
-	cp := make([]byte, len(f.Payload))
-	copy(cp, f.Payload)
-	return &FrameWithPayload{
-		Frame:   f.Frame,
-		Payload: cp,
-	}
-}
-
-// NewErrorFrame helper for creating an error frame with a textual payload.
-func NewErrorFrame(msg FrameType, code StatusCode, err error) FrameWithPayload {
-	var b []byte
-	if err != nil {
-		b = []byte(err.Error())
-	}
-	return MakeFrameWithPayload(msg, code, b)
-}
-
-// IsSuccess returns true if the status code indicates success in the
-// conventional HTTP style range (200–299). This mirrors previous usage patterns.
-func (f *FrameWithPayload) IsSuccess() bool {
-	return f != nil && f.StatusCode >= 200 && f.StatusCode < 300
-}

go.mod

@@ -3,6 +3,7 @@ module git.tornberg.me/go-cart-actor
 go 1.25.1
 
 require (
+	github.com/gogo/protobuf v1.3.2
 	github.com/google/uuid v1.6.0
 	github.com/matst80/slask-finder v0.0.0-20251009175145-ce05aff5a548
 	github.com/prometheus/client_golang v1.23.2
@@ -20,8 +21,10 @@ require (
 	github.com/bits-and-blooms/bitset v1.24.0 // indirect
 	github.com/cespare/xxhash/v2 v2.3.0 // indirect
 	github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc // indirect
+	github.com/dprotaso/go-yit v0.0.0-20220510233725-9ba8df137936 // indirect
 	github.com/emicklei/go-restful/v3 v3.13.0 // indirect
 	github.com/fxamacker/cbor/v2 v2.9.0 // indirect
+	github.com/getkin/kin-openapi v0.132.0 // indirect
 	github.com/go-logr/logr v1.4.3 // indirect
 	github.com/go-openapi/jsonpointer v0.22.1 // indirect
 	github.com/go-openapi/jsonreference v0.21.2 // indirect
@@ -37,32 +40,46 @@ require (
 	github.com/go-openapi/swag/stringutils v0.25.1 // indirect
 	github.com/go-openapi/swag/typeutils v0.25.1 // indirect
 	github.com/go-openapi/swag/yamlutils v0.25.1 // indirect
-	github.com/gogo/protobuf v1.3.2 // indirect
 	github.com/google/gnostic-models v0.7.0 // indirect
 	github.com/google/go-cmp v0.7.0 // indirect
 	github.com/gorilla/schema v1.4.1 // indirect
+	github.com/josharian/intern v1.0.0 // indirect
 	github.com/json-iterator/go v1.1.12 // indirect
+	github.com/mailru/easyjson v0.7.7 // indirect
 	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // 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/oapi-codegen/oapi-codegen/v2 v2.5.0 // 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 v1.0.0 // indirect
 	github.com/prometheus/client_model v0.6.2 // indirect
 	github.com/prometheus/common v0.67.1 // indirect
 	github.com/prometheus/procfs v0.17.0 // indirect
+	github.com/speakeasy-api/jsonpath v0.6.0 // indirect
+	github.com/speakeasy-api/openapi-overlay v0.10.2 // indirect
 	github.com/spf13/pflag v1.0.6 // indirect
+	github.com/vmware-labs/yaml-jsonpath v0.3.2 // indirect
 	github.com/x448/float16 v0.8.4 // indirect
 	go.yaml.in/yaml/v2 v2.4.3 // indirect
 	go.yaml.in/yaml/v3 v3.0.4 // indirect
+	golang.org/x/mod v0.28.0 // indirect
 	golang.org/x/net v0.46.0 // indirect
 	golang.org/x/oauth2 v0.32.0 // indirect
+	golang.org/x/sync v0.17.0 // indirect
 	golang.org/x/sys v0.37.0 // indirect
 	golang.org/x/term v0.36.0 // indirect
 	golang.org/x/text v0.30.0 // indirect
 	golang.org/x/time v0.14.0 // indirect
+	golang.org/x/tools v0.37.0 // indirect
 	google.golang.org/genproto/googleapis/rpc v0.0.0-20251007200510-49b9836ed3ff // 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 v0.0.0-20250910181357-589584f1c912 // indirect
 	k8s.io/utils v0.0.0-20251002143259-bc988d571ff4 // indirect
@@ -71,3 +88,5 @@ require (
 	sigs.k8s.io/structured-merge-diff/v6 v6.3.0 // indirect
 	sigs.k8s.io/yaml v1.6.0 // indirect
 )
+
+tool github.com/oapi-codegen/oapi-codegen/v2/cmd/oapi-codegen

go.sum

@@ -7,14 +7,25 @@ github.com/bits-and-blooms/bitset v1.24.0 h1:H4x4TuulnokZKvHLfzVRTHJfFfnHEeSYJiz
 github.com/bits-and-blooms/bitset v1.24.0/go.mod h1:7hO7Gc7Pp1vODcmWvKMRA9BNmbv6a/7QIWpPxHddWR8=
 github.com/cespare/xxhash/v2 v2.3.0 h1:UL815xU9SqsFlibzuggzjXhog7bL6oX9BbNZnL2UFvs=
 github.com/cespare/xxhash/v2 v2.3.0/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
+github.com/chzyer/logex v1.1.10/go.mod h1:+Ywpsq7O8HXn0nuIou7OrIPyXbp3wmkHB+jjWRnGsAI=
+github.com/chzyer/readline v0.0.0-20180603132655-2972be24d48e/go.mod h1:nSuG5e5PlCu98SY8svDHJxuZscDgtXS6KTTbou5AhLI=
+github.com/chzyer/test v0.0.0-20180213035817-a1ea475d72b1/go.mod h1:Q3SI9o4m/ZMnBNeIyt5eFwwo7qiLfzFZmjNmxjkiQlU=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc h1:U9qPSI2PIWSS1VwoXQT9A3Wy9MM3WgvqSxFWenqJduM=
 github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/dprotaso/go-yit v0.0.0-20191028211022-135eb7262960/go.mod h1:9HQzr9D/0PGwMEbC3d5AB7oi67+h4TsQqItC1GVYG58=
+github.com/dprotaso/go-yit v0.0.0-20220510233725-9ba8df137936 h1:PRxIJD8XjimM5aTknUK9w6DHLDox2r2M3DI4i2pnd3w=
+github.com/dprotaso/go-yit v0.0.0-20220510233725-9ba8df137936/go.mod h1:ttYvX5qlB+mlV1okblJqcSMtR4c52UKxDiX9GRBS8+Q=
 github.com/emicklei/go-restful/v3 v3.13.0 h1:C4Bl2xDndpU6nJ4bc1jXd+uTmYPVUwkD6bFY/oTyCes=
 github.com/emicklei/go-restful/v3 v3.13.0/go.mod h1:6n3XBCmQQb25CM2LCACGz8ukIrRry+4bhvbpWn3mrbc=
+github.com/fsnotify/fsnotify v1.4.7/go.mod h1:jwhsz4b93w/PPRr/qN1Yymfu8t87LnFCMoQvtojpjFo=
+github.com/fsnotify/fsnotify v1.4.9 h1:hsms1Qyu0jgnwNXIxa+/V/PDsU6CfLf6CNO8H7IWoS4=
+github.com/fsnotify/fsnotify v1.4.9/go.mod h1:znqG4EE+3YCdAaPaxE2ZRY/06pZUdp0tY4IgpuI1SZQ=
 github.com/fxamacker/cbor/v2 v2.9.0 h1:NpKPmjDBgUfBms6tr6JZkTHtfFGcMKsw3eGcmD/sapM=
 github.com/fxamacker/cbor/v2 v2.9.0/go.mod h1:vM4b+DJCtHn+zz7h3FFp/hDAI9WNWCsZj23V5ytsSxQ=
+github.com/getkin/kin-openapi v0.132.0 h1:3ISeLMsQzcb5v26yeJrBcdTCEQTag36ZjaGk7MIRUwk=
+github.com/getkin/kin-openapi v0.132.0/go.mod h1:3OlG51PCYNsPByuiMB0t4fjnNlIDnaEDsjiKUV8nL58=
 github.com/go-logr/logr v1.4.3 h1:CjnDlHq8ikf6E492q6eKboGOC0T8CDaOvkHCIg8idEI=
 github.com/go-logr/logr v1.4.3/go.mod h1:9T104GzyrTigFIr8wt5mBrctHMim0Nb2HLGrmQ40KvY=
 github.com/go-logr/stdr v1.2.2 h1:hSWxHoqTgW2S2qGc0LTAI563KZ5YKYRhT3MFKZMbjag=
@@ -49,35 +60,62 @@ github.com/go-openapi/swag/typeutils v0.25.1 h1:rD/9HsEQieewNt6/k+JBwkxuAHktFtH3
 github.com/go-openapi/swag/typeutils v0.25.1/go.mod h1:9McMC/oCdS4BKwk2shEB7x17P6HmMmA6dQRtAkSnNb8=
 github.com/go-openapi/swag/yamlutils v0.25.1 h1:mry5ez8joJwzvMbaTGLhw8pXUnhDK91oSJLDPF1bmGk=
 github.com/go-openapi/swag/yamlutils v0.25.1/go.mod h1:cm9ywbzncy3y6uPm/97ysW8+wZ09qsks+9RS8fLWKqg=
+github.com/go-task/slim-sprig v0.0.0-20210107165309-348f09dbbbc0 h1:p104kn46Q8WdvHunIJ9dAyjPVtrBPhSr3KT2yUst43I=
+github.com/go-task/slim-sprig v0.0.0-20210107165309-348f09dbbbc0/go.mod h1:fyg7847qk6SyHyPtNmDHnmrv/HOrqktSC+C9fM+CJOE=
 github.com/go-task/slim-sprig/v3 v3.0.0 h1:sUs3vkvUymDpBKi3qH1YSqBQk9+9D/8M2mN1vB6EwHI=
 github.com/go-task/slim-sprig/v3 v3.0.0/go.mod h1:W848ghGpv3Qj3dhTPRyJypKRiqCdHZiAzKg9hl15HA8=
+github.com/go-test/deep v1.0.8 h1:TDsG77qcSprGbC6vTN8OuXp5g+J+b5Pcguhf7Zt61VM=
+github.com/go-test/deep v1.0.8/go.mod h1:5C2ZWiW0ErCdrYzpqxLbTX7MG14M9iiw8DgHncVwcsE=
 github.com/gogo/protobuf v1.3.2 h1:Ov1cvc58UF3b5XjBnZv7+opcTcQFZebYjWzi34vdm4Q=
 github.com/gogo/protobuf v1.3.2/go.mod h1:P1XiOD3dCwIKUDQYPy72D8LYyHL2YPYrpS2s69NZV8Q=
+github.com/golang/protobuf v1.2.0/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
+github.com/golang/protobuf v1.4.0-rc.1/go.mod h1:ceaxUfeHdC40wWswd/P6IGgMaK3YpKi5j83Wpe3EHw8=
+github.com/golang/protobuf v1.4.0-rc.1.0.20200221234624-67d41d38c208/go.mod h1:xKAWHe0F5eneWXFV3EuXVDTCmh+JuBKY0li0aMyXATA=
+github.com/golang/protobuf v1.4.0-rc.2/go.mod h1:LlEzMj4AhA7rCAGe4KMBDvJI+AwstrUpVNzEA03Pprs=
+github.com/golang/protobuf v1.4.0-rc.4.0.20200313231945-b860323f09d0/go.mod h1:WU3c8KckQ9AFe+yFwt9sWVRKCVIyN9cPHBJSNnbL67w=
+github.com/golang/protobuf v1.4.0/go.mod h1:jodUvKwWbYaEsadDk5Fwe5c77LiNKVO9IDvqG2KuDX0=
+github.com/golang/protobuf v1.4.2/go.mod h1:oDoupMAO8OvCJWAcko0GGGIgR6R6ocIYbsSw735rRwI=
+github.com/golang/protobuf v1.5.0/go.mod h1:FsONVRAS9T7sI+LIUmWTfcYkHO4aIWwzhcaSAoJOfIk=
+github.com/golang/protobuf v1.5.2/go.mod h1:XVQd3VNwM+JqD3oG2Ue2ip4fOMUkwXdXDdiuN0vRsmY=
 github.com/golang/protobuf v1.5.4 h1:i7eJL8qZTpSEXOPTxNKhASYpMn+8e5Q6AdndVa1dWek=
 github.com/golang/protobuf v1.5.4/go.mod h1:lnTiLA8Wa4RWRcIUkrtSVa5nRhsEGBg48fD6rSs7xps=
 github.com/google/gnostic-models v0.7.0 h1:qwTtogB15McXDaNqTZdzPJRHvaVJlAl+HVQnLmJEJxo=
 github.com/google/gnostic-models v0.7.0/go.mod h1:whL5G0m6dmc5cPxKc5bdKdEN3UjI7OUGxBlw57miDrQ=
+github.com/google/go-cmp v0.3.0/go.mod h1:8QqcDgzrUqlUb/G2PQTWiueGozuR1884gddMywk6iLU=
+github.com/google/go-cmp v0.3.1/go.mod h1:8QqcDgzrUqlUb/G2PQTWiueGozuR1884gddMywk6iLU=
+github.com/google/go-cmp v0.4.0/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
+github.com/google/go-cmp v0.5.5/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
 github.com/google/go-cmp v0.7.0 h1:wk8382ETsv4JYUZwIsn6YpYiWiBsYLSJiTsyBybVuN8=
 github.com/google/go-cmp v0.7.0/go.mod h1:pXiqmnSA92OHEEa9HXL2W4E7lf9JzCmGVUdgjX3N/iU=
 github.com/google/gofuzz v1.0.0/go.mod h1:dBl0BpW6vV/+mYPU4Po3pmUjxk6FQPldtuIdl/M65Eg=
+github.com/google/pprof v0.0.0-20210407192527-94a9f03dee38/go.mod h1:kpwsk12EmLew5upagYY7GY0pfYCcupk39gWOCRROcvE=
 github.com/google/pprof v0.0.0-20241029153458-d1b30febd7db h1:097atOisP2aRj7vFgYQBbFN4U4JNXUNYpxael3UzMyo=
 github.com/google/pprof v0.0.0-20241029153458-d1b30febd7db/go.mod h1:vavhavw2zAxS5dIdcRluK6cSGGPlZynqzFM8NdvU144=
 github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
 github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
 github.com/gorilla/schema v1.4.1 h1:jUg5hUjCSDZpNGLuXQOgIWGdlgrIdYvgQ0wZtdK1M3E=
 github.com/gorilla/schema v1.4.1/go.mod h1:Dg5SSm5PV60mhF2NFaTV1xuYYj8tV8NOPRo4FggUMnM=
+github.com/hpcloud/tail v1.0.0/go.mod h1:ab1qPbhIpdTxEkNHXyeSf5vhxWSCs/tWer42PpOxQnU=
+github.com/ianlancetaylor/demangle v0.0.0-20200824232613-28f6c0f3b639/go.mod h1:aSSvb/t6k1mPoxDqO4vJh6VOCGPwU4O0C2/Eqndh1Sc=
+github.com/josharian/intern v1.0.0 h1:vlS4z54oSdjm0bgjRigI+G1HpF+tI+9rE5LLzOg8HmY=
+github.com/josharian/intern v1.0.0/go.mod h1:5DoeVV0s6jJacbCEi61lwdGj/aVlrQvzHFFd8Hwg//Y=
 github.com/json-iterator/go v1.1.12 h1:PV8peI4a0ysnczrg+LtxykD8LfKY9ML6u2jnxaEnrnM=
 github.com/json-iterator/go v1.1.12/go.mod h1:e30LSqwooZae/UwlEbR2852Gd8hjQvJoHmT4TnhNGBo=
 github.com/kisielk/errcheck v1.5.0/go.mod h1:pFxgyoBC7bSaBwPgfKdkLd5X25qrDl4LWUI2bnpBCr8=
 github.com/kisielk/gotool v1.0.0/go.mod h1:XhKaO+MFFWcvkIS/tQcRk01m1F5IRFswLeQ+oQHNcck=
 github.com/klauspost/compress v1.18.0 h1:c/Cqfb0r+Yi+JtIEq73FWXVkRonBlf0CRNYc8Zttxdo=
 github.com/klauspost/compress v1.18.0/go.mod h1:2Pp+KzxcywXVXMr50+X0Q/Lsb43OQHYWRCY2AiWywWQ=
+github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
 github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=
 github.com/kr/pretty v0.3.1/go.mod h1:hoEshYVHaxMs3cyo3Yncou5ZscifuDolrwPKZanG3xk=
+github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
+github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
 github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
 github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
 github.com/kylelemons/godebug v1.1.0 h1:RPNrshWIDI6G2gRW9EHilWtl7Z6Sb1BR0xunSBf0SNc=
 github.com/kylelemons/godebug v1.1.0/go.mod h1:9/0rRGxNHcop5bhtWyNeEfOS8JIWk580+fNqagV/RAw=
+github.com/mailru/easyjson v0.7.7 h1:UGYAvKxe3sBsEDzO8ZeWOSlIQfWFlxbzLZe7hwFURr0=
+github.com/mailru/easyjson v0.7.7/go.mod h1:xzfreul335JAWq5oZzymOObrkdz5UnU4kGfJJLY9Nlc=
 github.com/matst80/slask-finder v0.0.0-20251009175145-ce05aff5a548 h1:lkxVz5lNPlU78El49cx1c3Rxo/bp7Gbzp2BjSRFgg1U=
 github.com/matst80/slask-finder v0.0.0-20251009175145-ce05aff5a548/go.mod h1:k4lo5gFYb3AqrgftlraCnv95xvjB/w8udRqJQJ12mAE=
 github.com/modern-go/concurrent v0.0.0-20180228061459-e0a39a4cb421/go.mod h1:6dJC0mAP4ikYIbvyc7fijjWJddQyLn8Ig3JB5CqoB9Q=
@@ -86,14 +124,38 @@ github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd/go.mod h1:6dJ
 github.com/modern-go/reflect2 v1.0.2/go.mod h1:yWuevngMOJpCy52FWWMvUC8ws7m/LJsjYzDa0/r8luk=
 github.com/modern-go/reflect2 v1.0.3-0.20250322232337-35a7c28c31ee h1:W5t00kpgFdJifH4BDsTlE89Zl93FEloxaWZfGcifgq8=
 github.com/modern-go/reflect2 v1.0.3-0.20250322232337-35a7c28c31ee/go.mod h1:yWuevngMOJpCy52FWWMvUC8ws7m/LJsjYzDa0/r8luk=
+github.com/mohae/deepcopy v0.0.0-20170929034955-c48cc78d4826 h1:RWengNIwukTxcDr9M+97sNutRR1RKhG96O6jWumTTnw=
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@@ -144,26 +218,50 @@ golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8U
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@@ -171,6 +269,7 @@ golang.org/x/time v0.14.0/go.mod h1:eL/Oa2bBBK0TkX57Fyni+NgnyQQN4LitPmob2Hjnqw4=
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@@ -184,15 +283,34 @@ google.golang.org/genproto/googleapis/rpc v0.0.0-20251007200510-49b9836ed3ff h1:
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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
-}

grpc_integration_test.go

@@ -1,135 +0,0 @@
-package main
-
-import (
-	"bytes"
-	"context"
-	"encoding/json"
-	"fmt"
-	"testing"
-	"time"
-
-	messages "git.tornberg.me/go-cart-actor/proto"
-	"google.golang.org/grpc"
-)
-
-// TestCartActorMutationAndState validates end-to-end gRPC mutation + state retrieval
-// against a locally started gRPC server (single-node scenario).
-// This test uses AddItemType directly to avoid hitting external product
-// fetching logic (FetchItem) which would require network I/O.
-func TestCartActorMutationAndState(t *testing.T) {
-	// Setup local grain pool + synced pool (no discovery, single host)
-	pool := NewGrainLocalPool(1024, time.Minute, spawn)
-	synced, err := NewSyncedPool(pool, "127.0.0.1", nil)
-	if err != nil {
-		t.Fatalf("NewSyncedPool error: %v", err)
-	}
-
-	// Start gRPC server (CartActor + ControlPlane) on :1337
-	grpcSrv, err := StartGRPCServer(":1337", pool, synced)
-	if err != nil {
-		t.Fatalf("StartGRPCServer error: %v", err)
-	}
-	defer grpcSrv.GracefulStop()
-
-	// Dial the local server
-	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
-	defer cancel()
-	conn, err := grpc.DialContext(ctx, "127.0.0.1:1337",
-		grpc.WithInsecure(),
-		grpc.WithBlock(),
-	)
-	if err != nil {
-		t.Fatalf("grpc.Dial error: %v", err)
-	}
-	defer conn.Close()
-
-	cartClient := messages.NewCartActorClient(conn)
-
-	// Create a short cart id (<=16 chars so it fits into the fixed CartId 16-byte array cleanly)
-	cartID := fmt.Sprintf("cart-%d", time.Now().UnixNano())
-
-	// Build an AddItem payload (bypasses FetchItem to keep test deterministic)
-	addItem := &messages.AddItem{
-		ItemId:   1,
-		Quantity: 1,
-		Price:    1000,
-		OrgPrice: 1000,
-		Sku:      "test-sku",
-		Name:     "Test SKU",
-		Image:    "/img.png",
-		Stock:    2, // InStock
-		Tax:      2500,
-		Country:  "se",
-	}
-
-	// Marshal underlying mutation payload using the existing handler code path
-	handler, ok := Handlers[AddItemType]
-	if !ok {
-		t.Fatalf("Handler for AddItemType missing")
-	}
-	payloadData, err := getSerializedPayload(handler, AddItemType, addItem)
-	if err != nil {
-		t.Fatalf("serialize add item: %v", err)
-	}
-
-	// Issue Mutate RPC
-	mutResp, err := cartClient.Mutate(context.Background(), &messages.MutationRequest{
-		CartId:          cartID,
-		Type:            messages.MutationType(AddItemType),
-		Payload:         payloadData,
-		ClientTimestamp: time.Now().Unix(),
-	})
-	if err != nil {
-		t.Fatalf("Mutate RPC error: %v", err)
-	}
-	if mutResp.StatusCode != 200 {
-		t.Fatalf("Mutate returned non-200 status: %d payload=%s", mutResp.StatusCode, string(mutResp.Payload))
-	}
-
-	// Decode cart state JSON and validate
-	state := &CartGrain{}
-	if err := json.Unmarshal(mutResp.Payload, state); err != nil {
-		t.Fatalf("Unmarshal mutate cart state: %v\nPayload: %s", err, string(mutResp.Payload))
-	}
-	if len(state.Items) != 1 {
-		t.Fatalf("Expected 1 item after mutation, got %d", len(state.Items))
-	}
-	if state.Items[0].Sku != "test-sku" {
-		t.Fatalf("Unexpected item SKU: %s", state.Items[0].Sku)
-	}
-
-	// Issue GetState RPC
-	getResp, err := cartClient.GetState(context.Background(), &messages.StateRequest{
-		CartId: cartID,
-	})
-	if err != nil {
-		t.Fatalf("GetState RPC error: %v", err)
-	}
-	if getResp.StatusCode != 200 {
-		t.Fatalf("GetState returned non-200 status: %d payload=%s", getResp.StatusCode, string(getResp.Payload))
-	}
-
-	state2 := &CartGrain{}
-	if err := json.Unmarshal(getResp.Payload, state2); err != nil {
-		t.Fatalf("Unmarshal get state: %v", err)
-	}
-	if len(state2.Items) != 1 {
-		t.Fatalf("Expected 1 item in GetState, got %d", len(state2.Items))
-	}
-	if state2.Items[0].Sku != "test-sku" {
-		t.Fatalf("Unexpected SKU in GetState: %s", state2.Items[0].Sku)
-	}
-}
-
-// getSerializedPayload serializes a mutation proto using the registered handler.
-func getSerializedPayload(handler MessageHandler, msgType uint16, content interface{}) ([]byte, error) {
-	msg := &Message{
-		Type:    msgType,
-		Content: content,
-	}
-	var buf bytes.Buffer
-	if err := handler.Write(msg, &buf); err != nil {
-		return nil, err
-	}
-	return buf.Bytes(), nil
-}

grpc_server.go

@@ -1,379 +0,0 @@
-package main
-
-import (
-	"context"
-	"errors"
-	"fmt"
-	"log"
-	"net"
-	"time"
-
-	proto "git.tornberg.me/go-cart-actor/proto" // underlying generated package name is 'messages'
-	"github.com/prometheus/client_golang/prometheus"
-	"github.com/prometheus/client_golang/prometheus/promauto"
-	"google.golang.org/grpc"
-	"google.golang.org/grpc/codes"
-	"google.golang.org/grpc/status"
-)
-
-// -----------------------------------------------------------------------------
-// Metrics
-// -----------------------------------------------------------------------------
-
-var (
-	grpcMutateDuration = promauto.NewHistogram(prometheus.HistogramOpts{
-		Name:    "cart_grpc_mutate_duration_seconds",
-		Help:    "Duration of CartActor.Mutate RPCs",
-		Buckets: prometheus.DefBuckets,
-	})
-	grpcMutateErrors = promauto.NewCounter(prometheus.CounterOpts{
-		Name: "cart_grpc_mutate_errors_total",
-		Help: "Total number of failed CartActor.Mutate RPCs",
-	})
-	grpcStateDuration = promauto.NewHistogram(prometheus.HistogramOpts{
-		Name:    "cart_grpc_get_state_duration_seconds",
-		Help:    "Duration of CartActor.GetState RPCs",
-		Buckets: prometheus.DefBuckets,
-	})
-	grpcControlDuration = promauto.NewHistogram(prometheus.HistogramOpts{
-		Name:    "cart_grpc_control_duration_seconds",
-		Help:    "Duration of ControlPlane RPCs",
-		Buckets: prometheus.DefBuckets,
-	})
-	grpcControlErrors = promauto.NewCounter(prometheus.CounterOpts{
-		Name: "cart_grpc_control_errors_total",
-		Help: "Total number of failed ControlPlane RPCs",
-	})
-)
-
-// timeTrack wraps a closure and records duration into the supplied histogram.
-func timeTrack(hist prometheus.Observer, fn func() error) (err error) {
-	start := time.Now()
-	defer func() {
-		hist.Observe(time.Since(start).Seconds())
-	}()
-	return fn()
-}
-
-// -----------------------------------------------------------------------------
-// CartActor Service Implementation
-// -----------------------------------------------------------------------------
-
-type cartActorService struct {
-	proto.UnimplementedCartActorServer
-	pool GrainPool
-}
-
-func newCartActorService(pool GrainPool) *cartActorService {
-	return &cartActorService{pool: pool}
-}
-
-func (s *cartActorService) Mutate(ctx context.Context, req *proto.MutationRequest) (*proto.MutationReply, error) {
-	var reply *proto.MutationReply
-	err := timeTrack(grpcMutateDuration, func() error {
-		if req == nil {
-			return status.Error(codes.InvalidArgument, "request is nil")
-		}
-		if req.CartId == "" {
-			return status.Error(codes.InvalidArgument, "cart_id is empty")
-		}
-		mt := uint16(req.Type.Number())
-		handler, ok := Handlers[mt]
-		if !ok {
-			return status.Errorf(codes.InvalidArgument, "unknown mutation type %d", mt)
-		}
-		content, err := handler.Read(req.Payload)
-		if err != nil {
-			return status.Errorf(codes.InvalidArgument, "decode payload: %v", err)
-		}
-
-		ts := req.ClientTimestamp
-		if ts == 0 {
-			ts = time.Now().Unix()
-		}
-		msg := Message{
-			Type:      mt,
-			TimeStamp: &ts,
-			Content:   content,
-		}
-
-		frame, err := s.pool.Process(ToCartId(req.CartId), msg)
-		if err != nil {
-			return err
-		}
-		reply = &proto.MutationReply{
-			StatusCode: int32(frame.StatusCode),
-			Payload:    frame.Payload,
-		}
-		return nil
-	})
-	if err != nil {
-		grpcMutateErrors.Inc()
-		return nil, err
-	}
-	return reply, nil
-}
-
-func (s *cartActorService) GetState(ctx context.Context, req *proto.StateRequest) (*proto.StateReply, error) {
-	var reply *proto.StateReply
-	err := timeTrack(grpcStateDuration, func() error {
-		if req == nil || req.CartId == "" {
-			return status.Error(codes.InvalidArgument, "cart_id is empty")
-		}
-		frame, err := s.pool.Get(ToCartId(req.CartId))
-		if err != nil {
-			return err
-		}
-		reply = &proto.StateReply{
-			StatusCode: int32(frame.StatusCode),
-			Payload:    frame.Payload,
-		}
-		return nil
-	})
-	if err != nil {
-		return nil, err
-	}
-	return reply, nil
-}
-
-// -----------------------------------------------------------------------------
-// ControlPlane Service Implementation
-// -----------------------------------------------------------------------------
-
-// controlPlaneService directly leverages SyncedPool internals (same package).
-// NOTE: This is a transitional adapter; once the legacy frame-based code is
-// removed, related fields/methods in SyncedPool can be slimmed.
-type controlPlaneService struct {
-	proto.UnimplementedControlPlaneServer
-	pool *SyncedPool
-}
-
-func newControlPlaneService(pool *SyncedPool) *controlPlaneService {
-	return &controlPlaneService{pool: pool}
-}
-
-func (s *controlPlaneService) Ping(ctx context.Context, _ *proto.Empty) (*proto.PingReply, error) {
-	var reply *proto.PingReply
-	err := timeTrack(grpcControlDuration, func() error {
-		reply = &proto.PingReply{
-			Host:     s.pool.Hostname,
-			UnixTime: time.Now().Unix(),
-		}
-		return nil
-	})
-	if err != nil {
-		grpcControlErrors.Inc()
-		return nil, err
-	}
-	return reply, nil
-}
-
-func (s *controlPlaneService) Negotiate(ctx context.Context, req *proto.NegotiateRequest) (*proto.NegotiateReply, error) {
-	var reply *proto.NegotiateReply
-	err := timeTrack(grpcControlDuration, func() error {
-		if req == nil {
-			return status.Error(codes.InvalidArgument, "request is nil")
-		}
-		// Add unknown hosts
-		for _, host := range req.KnownHosts {
-			if host == "" || host == s.pool.Hostname {
-				continue
-			}
-			if !s.pool.IsKnown(host) {
-				go s.pool.AddRemote(host)
-			}
-		}
-		// Build healthy host list
-		hosts := make([]string, 0)
-		for _, r := range s.pool.GetHealthyRemotes() {
-			hosts = append(hosts, r.Host)
-		}
-		hosts = append(hosts, s.pool.Hostname)
-		reply = &proto.NegotiateReply{
-			Hosts: hosts,
-		}
-		return nil
-	})
-	if err != nil {
-		grpcControlErrors.Inc()
-		return nil, err
-	}
-	return reply, nil
-}
-
-func (s *controlPlaneService) GetCartIds(ctx context.Context, _ *proto.Empty) (*proto.CartIdsReply, error) {
-	var reply *proto.CartIdsReply
-	err := timeTrack(grpcControlDuration, func() error {
-		s.pool.mu.RLock()
-		defer s.pool.mu.RUnlock()
-		ids := make([]string, 0, len(s.pool.local.grains))
-		for id, g := range s.pool.local.grains {
-			if g == nil {
-				continue
-			}
-			if id.String() == "" {
-				continue
-			}
-			ids = append(ids, id.String())
-		}
-		reply = &proto.CartIdsReply{
-			CartIds: ids,
-		}
-		return nil
-	})
-	if err != nil {
-		grpcControlErrors.Inc()
-		return nil, err
-	}
-	return reply, nil
-}
-
-func (s *controlPlaneService) ConfirmOwner(ctx context.Context, req *proto.OwnerChangeRequest) (*proto.OwnerChangeAck, error) {
-	var reply *proto.OwnerChangeAck
-	err := timeTrack(grpcControlDuration, func() error {
-		if req == nil || req.CartId == "" || req.NewHost == "" {
-			return status.Error(codes.InvalidArgument, "cart_id or new_host missing")
-		}
-		id := ToCartId(req.CartId)
-		newHost := req.NewHost
-
-		// Mirror GrainOwnerChangeHandler semantics
-		log.Printf("gRPC ConfirmOwner: cart %s newHost=%s", id, newHost)
-		for _, r := range s.pool.remoteHosts {
-			if r.Host == newHost && r.IsHealthy() {
-				go s.pool.SpawnRemoteGrain(id, newHost)
-				break
-			}
-		}
-		go s.pool.AddRemote(newHost)
-
-		reply = &proto.OwnerChangeAck{
-			Accepted: true,
-			Message:  "ok",
-		}
-		return nil
-	})
-	if err != nil {
-		grpcControlErrors.Inc()
-		return nil, err
-	}
-	return reply, nil
-}
-
-func (s *controlPlaneService) Closing(ctx context.Context, notice *proto.ClosingNotice) (*proto.OwnerChangeAck, error) {
-	var reply *proto.OwnerChangeAck
-	err := timeTrack(grpcControlDuration, func() error {
-		if notice == nil || notice.Host == "" {
-			return status.Error(codes.InvalidArgument, "host missing")
-		}
-		host := notice.Host
-		s.pool.mu.RLock()
-		_, exists := s.pool.remoteHosts[host]
-		s.pool.mu.RUnlock()
-		if exists {
-			go s.pool.RemoveHost(host)
-		}
-		reply = &proto.OwnerChangeAck{
-			Accepted: true,
-			Message:  "removed",
-		}
-		return nil
-	})
-	if err != nil {
-		grpcControlErrors.Inc()
-		return nil, err
-	}
-	return reply, nil
-}
-
-// -----------------------------------------------------------------------------
-// Server Bootstrap
-// -----------------------------------------------------------------------------
-
-type GRPCServer struct {
-	server *grpc.Server
-	lis    net.Listener
-	addr   string
-}
-
-// StartGRPCServer sets up a gRPC server hosting both CartActor and ControlPlane services.
-// addr example: ":1337" (for combined) OR run two servers if you want separate ports.
-// For the migration we can host both on the same listener to reduce open ports.
-func StartGRPCServer(addr string, pool GrainPool, synced *SyncedPool, opts ...grpc.ServerOption) (*GRPCServer, error) {
-	if pool == nil {
-		return nil, errors.New("nil grain pool")
-	}
-	if synced == nil {
-		return nil, errors.New("nil synced pool")
-	}
-
-	lis, err := net.Listen("tcp", addr)
-	if err != nil {
-		return nil, fmt.Errorf("listen %s: %w", addr, err)
-	}
-
-	grpcServer := grpc.NewServer(opts...)
-	proto.RegisterCartActorServer(grpcServer, newCartActorService(pool))
-	proto.RegisterControlPlaneServer(grpcServer, newControlPlaneService(synced))
-
-	go func() {
-		log.Printf("gRPC server listening on %s", addr)
-		if serveErr := grpcServer.Serve(lis); serveErr != nil {
-			log.Printf("gRPC server stopped: %v", serveErr)
-		}
-	}()
-
-	return &GRPCServer{
-		server: grpcServer,
-		lis:    lis,
-		addr:   addr,
-	}, nil
-}
-
-// GracefulStop stops the server gracefully.
-func (s *GRPCServer) GracefulStop() {
-	if s == nil || s.server == nil {
-		return
-	}
-	s.server.GracefulStop()
-}
-
-// Addr returns the bound address.
-func (s *GRPCServer) Addr() string {
-	if s == nil {
-		return ""
-	}
-	return s.addr
-}
-
-// -----------------------------------------------------------------------------
-// Client Dial Helpers (used later by refactored remote grain + control plane)
-// -----------------------------------------------------------------------------
-
-// DialRemote establishes (or reuses externally) a gRPC client connection.
-func DialRemote(ctx context.Context, target string, opts ...grpc.DialOption) (*grpc.ClientConn, error) {
-	dialOpts := []grpc.DialOption{
-		grpc.WithInsecure(), // NOTE: Intentional for initial migration; replace with TLS / mTLS later.
-		grpc.WithBlock(),
-	}
-	dialOpts = append(dialOpts, opts...)
-	ctxDial, cancel := context.WithTimeout(ctx, 5*time.Second)
-	defer cancel()
-	conn, err := grpc.DialContext(ctxDial, target, dialOpts...)
-	if err != nil {
-		return nil, err
-	}
-	return conn, nil
-}
-
-// -----------------------------------------------------------------------------
-// Utility for converting internal errors to gRPC status (if needed later).
-// -----------------------------------------------------------------------------
-
-func grpcError(err error) error {
-	if err == nil {
-		return nil
-	}
-	// Extend mapping if we add richer error types.
-	return status.Error(codes.Internal, err.Error())
-}

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,
+        ),
+    };
+}

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-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
-}

pkg/actor/disk_storage.go

@@ -0,0 +1,137 @@
+package actor
+
+import (
+	"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(id uint64, grain Grain[V]) error
+	AppendEvent(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(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(grain, msg)
+	})
+}
+
+func (s *DiskStorage[V]) Close() {
+	s.save()
+	close(s.done)
+}
+
+func (s *DiskStorage[V]) AppendEvent(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 +1,41 @@
+package actor
+
+import (
+	"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(id uint64, mutation ...proto.Message) (*MutationResult[V], error)
+	Get(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)
+	IsHealthy() bool
+	IsKnown(string) bool
+	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 +1,119 @@
+package actor
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"net"
+	"time"
+
+	messages "git.tornberg.me/go-cart-actor/pkg/messages"
+	"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]
+}
+
+func (s *ControlServer[V]) AnnounceOwnership(ctx context.Context, req *messages.OwnershipAnnounce) (*messages.OwnerChangeAck, error) {
+	err := s.pool.HandleOwnershipChange(req.Host, req.Ids)
+	if err != nil {
+		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) {
+	err := s.pool.HandleRemoteExpiry(req.Host, req.Ids)
+	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) {
+	// log.Printf("got ping")
+	return &messages.PingReply{
+		Host:     s.pool.Hostname(),
+		UnixTime: time.Now().Unix(),
+	}, nil
+}
+
+// ControlPlane: Negotiate (merge host views)
+func (s *ControlServer[V]) Negotiate(ctx context.Context, req *messages.NegotiateRequest) (*messages.NegotiateReply, error) {
+
+	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) {
+	return &messages.ActorIdsReply{Ids: s.pool.GetLocalIds()}, nil
+}
+
+// ControlPlane: Closing (peer shutdown notification)
+func (s *ControlServer[V]) Closing(ctx context.Context, req *messages.ClosingNotice) (*messages.OwnerChangeAck, error) {
+	if req.GetHost() != "" {
+		s.pool.RemoveHost(req.GetHost())
+	}
+	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/mutation_registry.go

@@ -0,0 +1,226 @@
+package actor
+
+import (
+	"fmt"
+	"log"
+	"reflect"
+	"sync"
+
+	"github.com/gogo/protobuf/proto"
+)
+
+type ApplyResult struct {
+	Type     string        `json:"type"`
+	Mutation proto.Message `json:"mutation"`
+	Error    error         `json:"error,omitempty"`
+}
+
+type MutationRegistry interface {
+	Apply(grain any, msg ...proto.Message) ([]ApplyResult, error)
+	RegisterMutations(handlers ...MutationHandler)
+	Create(typeName string) (proto.Message, bool)
+	GetTypeName(msg proto.Message) (string, bool)
+	//GetStorageEvent(msg proto.Message) StorageEvent
+	//FromStorageEvent(event StorageEvent) (proto.Message, error)
+}
+
+type ProtoMutationRegistry struct {
+	mutationRegistryMu sync.RWMutex
+	mutationRegistry   map[reflect.Type]MutationHandler
+}
+
+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{},
+	}
+}
+
+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(grain any, msg ...proto.Message) ([]ApplyResult, error) {
+	results := make([]ApplyResult, 0, len(msg))
+
+	if grain == nil {
+		return results, fmt.Errorf("nil grain")
+	}
+	if msg == nil {
+		return results, fmt.Errorf("nil mutation message")
+	}
+
+	for _, m := range msg {
+		rt := indirectType(reflect.TypeOf(m))
+		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
+		}
+		err := entry.Handle(grain, m)
+		results = append(results, ApplyResult{Error: err, Type: rt.Name(), Mutation: m})
+	}
+
+	// if entry.updateTotals {
+	// 	grain.UpdateTotals()
+	// }
+
+	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 +1,134 @@
+package actor
+
+import (
+	"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(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(state, nil); err == nil {
+		t.Fatalf("expected error for nil mutation message")
+	}
+
+	// Apply unregistered message
+	if _, err := reg.Apply(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/simple_grain_pool.go

@@ -0,0 +1,433 @@
+package actor
+
+import (
+	"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(id uint64) (Grain[V], error)
+	spawnHost        func(host string) (Host, error)
+	storage          LogStorage[V]
+	ttl              time.Duration
+	poolSize         int
+
+	// 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(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]) 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)
+
+			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]) 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(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(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(id uint64, mutation ...proto.Message) (*MutationResult[*V], error) {
+	grain, err := p.getOrClaimGrain(id)
+	if err != nil {
+		return nil, err
+	}
+
+	mutations, err := p.mutationRegistry.Apply(grain, mutation...)
+	if err != nil {
+		return nil, err
+	}
+	if p.storage != nil {
+		go func() {
+			if err := p.storage.AppendEvent(id, mutation...); err != nil {
+				log.Printf("failed to store mutation for grain %d: %v", id, err)
+			}
+		}()
+	}
+	result, err := grain.GetCurrentState()
+	if err != nil {
+		return nil, err
+	}
+	return &MutationResult[*V]{
+		Result:    result,
+		Mutations: mutations,
+	}, nil
+}
+
+// Get returns the current state of a grain.
+func (p *SimpleGrainPool[V]) Get(id uint64) (*V, error) {
+	grain, err := p.getOrClaimGrain(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
+}
+
+// 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/discovery/discovery.go

@@ -1,4 +1,4 @@
-package main
+package discovery
 
 import (
 	"context"
@@ -11,11 +11,6 @@ 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
@@ -51,7 +46,7 @@ func (k *K8sDiscovery) Watch() (<-chan HostChange, error) {
 			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
 	}
@@ -60,6 +55,7 @@ func (k *K8sDiscovery) Watch() (<-chan HostChange, error) {
 		for event := range watcher.ResultChan() {
 
 			pod := event.Object.(*v1.Pod)
+			// log.Printf("pod change %+v", pod.Status.Phase == v1.PodRunning)
 			ch <- HostChange{
 				Host: pod.Status.PodIP,
 				Type: event.Type,

pkg/discovery/discovery_mock.go

@@ -0,0 +1,102 @@
+package discovery
+
+import (
+	"context"
+	"sync"
+
+	"k8s.io/apimachinery/pkg/watch"
+)
+
+// 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
+	}
+	for _, h := range m.hosts {
+		if h == host {
+			return
+		}
+	}
+	m.hosts = append(m.hosts, host)
+	if m.started {
+		m.events <- HostChange{Host: host, Type: watch.Added}
+	}
+}
+
+// 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, Type: watch.Deleted}
+	}
+}
+
+// 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"

pkg/discovery/types.go

@@ -0,0 +1,6 @@
+package discovery
+
+type Discovery interface {
+	Discover() ([]string, error)
+	Watch() (<-chan HostChange, error)
+}

pkg/messages/control_plane.pb.go

@@ -1,7 +1,7 @@
 // Code generated by protoc-gen-go. DO NOT EDIT.
 // versions:
-// 	protoc-gen-go v1.36.10
+// 	protoc-gen-go v1.36.5
-// 	protoc        v3.21.12
+// 	protoc        v5.29.3
 // source: control_plane.proto
 
 package messages
@@ -202,27 +202,27 @@ func (x *NegotiateReply) GetHosts() []string {
 }
 
 // CartIdsReply returns the list of cart IDs (string form) currently owned locally.
-type CartIdsReply struct {
+type ActorIdsReply struct {
 	state         protoimpl.MessageState `protogen:"open.v1"`
-	CartIds       []string               `protobuf:"bytes,1,rep,name=cart_ids,json=cartIds,proto3" json:"cart_ids,omitempty"`
+	Ids           []uint64               `protobuf:"varint,1,rep,packed,name=ids,proto3" json:"ids,omitempty"`
 	unknownFields protoimpl.UnknownFields
 	sizeCache     protoimpl.SizeCache
 }
 
-func (x *CartIdsReply) Reset() {
+func (x *ActorIdsReply) Reset() {
-	*x = CartIdsReply{}
+	*x = ActorIdsReply{}
 	mi := &file_control_plane_proto_msgTypes[4]
 	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 	ms.StoreMessageInfo(mi)
 }
 
-func (x *CartIdsReply) String() string {
+func (x *ActorIdsReply) String() string {
 	return protoimpl.X.MessageStringOf(x)
 }
 
-func (*CartIdsReply) ProtoMessage() {}
+func (*ActorIdsReply) ProtoMessage() {}
 
-func (x *CartIdsReply) ProtoReflect() protoreflect.Message {
+func (x *ActorIdsReply) ProtoReflect() protoreflect.Message {
 	mi := &file_control_plane_proto_msgTypes[4]
 	if x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
@@ -234,72 +234,19 @@ func (x *CartIdsReply) ProtoReflect() protoreflect.Message {
 	return mi.MessageOf(x)
 }
 
-// Deprecated: Use CartIdsReply.ProtoReflect.Descriptor instead.
+// Deprecated: Use ActorIdsReply.ProtoReflect.Descriptor instead.
-func (*CartIdsReply) Descriptor() ([]byte, []int) {
+func (*ActorIdsReply) Descriptor() ([]byte, []int) {
 	return file_control_plane_proto_rawDescGZIP(), []int{4}
 }
 
-func (x *CartIdsReply) GetCartIds() []string {
+func (x *ActorIdsReply) GetIds() []uint64 {
 	if x != nil {
-		return x.CartIds
+		return x.Ids
 	}
 	return nil
 }
 
-// OwnerChangeRequest notifies peers that ownership of a cart moved (or is moving) to new_host.
+// OwnerChangeAck retained as response type for Closing RPC (ConfirmOwner removed).
-type OwnerChangeRequest struct {
-	state         protoimpl.MessageState `protogen:"open.v1"`
-	CartId        string                 `protobuf:"bytes,1,opt,name=cart_id,json=cartId,proto3" json:"cart_id,omitempty"`
-	NewHost       string                 `protobuf:"bytes,2,opt,name=new_host,json=newHost,proto3" json:"new_host,omitempty"`
-	unknownFields protoimpl.UnknownFields
-	sizeCache     protoimpl.SizeCache
-}
-
-func (x *OwnerChangeRequest) Reset() {
-	*x = OwnerChangeRequest{}
-	mi := &file_control_plane_proto_msgTypes[5]
-	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
-	ms.StoreMessageInfo(mi)
-}
-
-func (x *OwnerChangeRequest) String() string {
-	return protoimpl.X.MessageStringOf(x)
-}
-
-func (*OwnerChangeRequest) ProtoMessage() {}
-
-func (x *OwnerChangeRequest) 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 OwnerChangeRequest.ProtoReflect.Descriptor instead.
-func (*OwnerChangeRequest) Descriptor() ([]byte, []int) {
-	return file_control_plane_proto_rawDescGZIP(), []int{5}
-}
-
-func (x *OwnerChangeRequest) GetCartId() string {
-	if x != nil {
-		return x.CartId
-	}
-	return ""
-}
-
-func (x *OwnerChangeRequest) GetNewHost() string {
-	if x != nil {
-		return x.NewHost
-	}
-	return ""
-}
-
-// OwnerChangeAck indicates acceptance or rejection of an ownership change.
 type OwnerChangeAck struct {
 	state         protoimpl.MessageState `protogen:"open.v1"`
 	Accepted      bool                   `protobuf:"varint,1,opt,name=accepted,proto3" json:"accepted,omitempty"`
@@ -310,7 +257,7 @@ type OwnerChangeAck struct {
 
 func (x *OwnerChangeAck) Reset() {
 	*x = OwnerChangeAck{}
-	mi := &file_control_plane_proto_msgTypes[6]
+	mi := &file_control_plane_proto_msgTypes[5]
 	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 	ms.StoreMessageInfo(mi)
 }
@@ -322,7 +269,7 @@ func (x *OwnerChangeAck) String() string {
 func (*OwnerChangeAck) ProtoMessage() {}
 
 func (x *OwnerChangeAck) ProtoReflect() protoreflect.Message {
-	mi := &file_control_plane_proto_msgTypes[6]
+	mi := &file_control_plane_proto_msgTypes[5]
 	if x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -335,7 +282,7 @@ func (x *OwnerChangeAck) ProtoReflect() protoreflect.Message {
 
 // Deprecated: Use OwnerChangeAck.ProtoReflect.Descriptor instead.
 func (*OwnerChangeAck) Descriptor() ([]byte, []int) {
-	return file_control_plane_proto_rawDescGZIP(), []int{6}
+	return file_control_plane_proto_rawDescGZIP(), []int{5}
 }
 
 func (x *OwnerChangeAck) GetAccepted() bool {
@@ -362,7 +309,7 @@ type ClosingNotice struct {
 
 func (x *ClosingNotice) Reset() {
 	*x = ClosingNotice{}
-	mi := &file_control_plane_proto_msgTypes[7]
+	mi := &file_control_plane_proto_msgTypes[6]
 	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 	ms.StoreMessageInfo(mi)
 }
@@ -374,7 +321,7 @@ func (x *ClosingNotice) String() string {
 func (*ClosingNotice) ProtoMessage() {}
 
 func (x *ClosingNotice) ProtoReflect() protoreflect.Message {
-	mi := &file_control_plane_proto_msgTypes[7]
+	mi := &file_control_plane_proto_msgTypes[6]
 	if x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -387,7 +334,7 @@ func (x *ClosingNotice) ProtoReflect() protoreflect.Message {
 
 // Deprecated: Use ClosingNotice.ProtoReflect.Descriptor instead.
 func (*ClosingNotice) Descriptor() ([]byte, []int) {
-	return file_control_plane_proto_rawDescGZIP(), []int{7}
+	return file_control_plane_proto_rawDescGZIP(), []int{6}
 }
 
 func (x *ClosingNotice) GetHost() string {
@@ -397,38 +344,174 @@ func (x *ClosingNotice) GetHost() string {
 	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
 
-const file_control_plane_proto_rawDesc = "" +
+var file_control_plane_proto_rawDesc = string([]byte{
-	"\n" +
+	0x0a, 0x13, 0x63, 0x6f, 0x6e, 0x74, 0x72, 0x6f, 0x6c, 0x5f, 0x70, 0x6c, 0x61, 0x6e, 0x65, 0x2e,
-	"\x13control_plane.proto\x12\bmessages\"\a\n" +
+	0x70, 0x72, 0x6f, 0x74, 0x6f, 0x12, 0x08, 0x6d, 0x65, 0x73, 0x73, 0x61, 0x67, 0x65, 0x73, 0x22,
-	"\x05Empty\"<\n" +
+	0x07, 0x0a, 0x05, 0x45, 0x6d, 0x70, 0x74, 0x79, 0x22, 0x3c, 0x0a, 0x09, 0x50, 0x69, 0x6e, 0x67,
-	"\tPingReply\x12\x12\n" +
+	0x52, 0x65, 0x70, 0x6c, 0x79, 0x12, 0x12, 0x0a, 0x04, 0x68, 0x6f, 0x73, 0x74, 0x18, 0x01, 0x20,
-	"\x04host\x18\x01 \x01(\tR\x04host\x12\x1b\n" +
+	0x01, 0x28, 0x09, 0x52, 0x04, 0x68, 0x6f, 0x73, 0x74, 0x12, 0x1b, 0x0a, 0x09, 0x75, 0x6e, 0x69,
-	"\tunix_time\x18\x02 \x01(\x03R\bunixTime\"3\n" +
+	0x78, 0x5f, 0x74, 0x69, 0x6d, 0x65, 0x18, 0x02, 0x20, 0x01, 0x28, 0x03, 0x52, 0x08, 0x75, 0x6e,
-	"\x10NegotiateRequest\x12\x1f\n" +
+	0x69, 0x78, 0x54, 0x69, 0x6d, 0x65, 0x22, 0x33, 0x0a, 0x10, 0x4e, 0x65, 0x67, 0x6f, 0x74, 0x69,
-	"\vknown_hosts\x18\x01 \x03(\tR\n" +
+	0x61, 0x74, 0x65, 0x52, 0x65, 0x71, 0x75, 0x65, 0x73, 0x74, 0x12, 0x1f, 0x0a, 0x0b, 0x6b, 0x6e,
-	"knownHosts\"&\n" +
+	0x6f, 0x77, 0x6e, 0x5f, 0x68, 0x6f, 0x73, 0x74, 0x73, 0x18, 0x01, 0x20, 0x03, 0x28, 0x09, 0x52,
-	"\x0eNegotiateReply\x12\x14\n" +
+	0x0a, 0x6b, 0x6e, 0x6f, 0x77, 0x6e, 0x48, 0x6f, 0x73, 0x74, 0x73, 0x22, 0x26, 0x0a, 0x0e, 0x4e,
-	"\x05hosts\x18\x01 \x03(\tR\x05hosts\")\n" +
+	0x65, 0x67, 0x6f, 0x74, 0x69, 0x61, 0x74, 0x65, 0x52, 0x65, 0x70, 0x6c, 0x79, 0x12, 0x14, 0x0a,
-	"\fCartIdsReply\x12\x19\n" +
+	0x05, 0x68, 0x6f, 0x73, 0x74, 0x73, 0x18, 0x01, 0x20, 0x03, 0x28, 0x09, 0x52, 0x05, 0x68, 0x6f,
-	"\bcart_ids\x18\x01 \x03(\tR\acartIds\"H\n" +
+	0x73, 0x74, 0x73, 0x22, 0x21, 0x0a, 0x0d, 0x41, 0x63, 0x74, 0x6f, 0x72, 0x49, 0x64, 0x73, 0x52,
-	"\x12OwnerChangeRequest\x12\x17\n" +
+	0x65, 0x70, 0x6c, 0x79, 0x12, 0x10, 0x0a, 0x03, 0x69, 0x64, 0x73, 0x18, 0x01, 0x20, 0x03, 0x28,
-	"\acart_id\x18\x01 \x01(\tR\x06cartId\x12\x19\n" +
+	0x04, 0x52, 0x03, 0x69, 0x64, 0x73, 0x22, 0x46, 0x0a, 0x0e, 0x4f, 0x77, 0x6e, 0x65, 0x72, 0x43,
-	"\bnew_host\x18\x02 \x01(\tR\anewHost\"F\n" +
+	0x68, 0x61, 0x6e, 0x67, 0x65, 0x41, 0x63, 0x6b, 0x12, 0x1a, 0x0a, 0x08, 0x61, 0x63, 0x63, 0x65,
-	"\x0eOwnerChangeAck\x12\x1a\n" +
+	0x70, 0x74, 0x65, 0x64, 0x18, 0x01, 0x20, 0x01, 0x28, 0x08, 0x52, 0x08, 0x61, 0x63, 0x63, 0x65,
-	"\baccepted\x18\x01 \x01(\bR\baccepted\x12\x18\n" +
+	0x70, 0x74, 0x65, 0x64, 0x12, 0x18, 0x0a, 0x07, 0x6d, 0x65, 0x73, 0x73, 0x61, 0x67, 0x65, 0x18,
-	"\amessage\x18\x02 \x01(\tR\amessage\"#\n" +
+	0x02, 0x20, 0x01, 0x28, 0x09, 0x52, 0x07, 0x6d, 0x65, 0x73, 0x73, 0x61, 0x67, 0x65, 0x22, 0x23,
-	"\rClosingNotice\x12\x12\n" +
+	0x0a, 0x0d, 0x43, 0x6c, 0x6f, 0x73, 0x69, 0x6e, 0x67, 0x4e, 0x6f, 0x74, 0x69, 0x63, 0x65, 0x12,
-	"\x04host\x18\x01 \x01(\tR\x04host2\xbc\x02\n" +
+	0x12, 0x0a, 0x04, 0x68, 0x6f, 0x73, 0x74, 0x18, 0x01, 0x20, 0x01, 0x28, 0x09, 0x52, 0x04, 0x68,
-	"\fControlPlane\x12,\n" +
+	0x6f, 0x73, 0x74, 0x22, 0x39, 0x0a, 0x11, 0x4f, 0x77, 0x6e, 0x65, 0x72, 0x73, 0x68, 0x69, 0x70,
-	"\x04Ping\x12\x0f.messages.Empty\x1a\x13.messages.PingReply\x12A\n" +
+	0x41, 0x6e, 0x6e, 0x6f, 0x75, 0x6e, 0x63, 0x65, 0x12, 0x12, 0x0a, 0x04, 0x68, 0x6f, 0x73, 0x74,
-	"\tNegotiate\x12\x1a.messages.NegotiateRequest\x1a\x18.messages.NegotiateReply\x125\n" +
+	0x18, 0x01, 0x20, 0x01, 0x28, 0x09, 0x52, 0x04, 0x68, 0x6f, 0x73, 0x74, 0x12, 0x10, 0x0a, 0x03,
-	"\n" +
+	0x69, 0x64, 0x73, 0x18, 0x02, 0x20, 0x03, 0x28, 0x04, 0x52, 0x03, 0x69, 0x64, 0x73, 0x22, 0x36,
-	"GetCartIds\x12\x0f.messages.Empty\x1a\x16.messages.CartIdsReply\x12F\n" +
+	0x0a, 0x0e, 0x45, 0x78, 0x70, 0x69, 0x72, 0x79, 0x41, 0x6e, 0x6e, 0x6f, 0x75, 0x6e, 0x63, 0x65,
-	"\fConfirmOwner\x12\x1c.messages.OwnerChangeRequest\x1a\x18.messages.OwnerChangeAck\x12<\n" +
+	0x12, 0x12, 0x0a, 0x04, 0x68, 0x6f, 0x73, 0x74, 0x18, 0x01, 0x20, 0x01, 0x28, 0x09, 0x52, 0x04,
-	"\aClosing\x12\x17.messages.ClosingNotice\x1a\x18.messages.OwnerChangeAckB\fZ\n" +
+	0x68, 0x6f, 0x73, 0x74, 0x12, 0x10, 0x0a, 0x03, 0x69, 0x64, 0x73, 0x18, 0x02, 0x20, 0x03, 0x28,
-	".;messagesb\x06proto3"
+	0x04, 0x52, 0x03, 0x69, 0x64, 0x73, 0x32, 0x8d, 0x03, 0x0a, 0x0c, 0x43, 0x6f, 0x6e, 0x74, 0x72,
+	0x6f, 0x6c, 0x50, 0x6c, 0x61, 0x6e, 0x65, 0x12, 0x2c, 0x0a, 0x04, 0x50, 0x69, 0x6e, 0x67, 0x12,
+	0x0f, 0x2e, 0x6d, 0x65, 0x73, 0x73, 0x61, 0x67, 0x65, 0x73, 0x2e, 0x45, 0x6d, 0x70, 0x74, 0x79,
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+	0x74, 0x65, 0x12, 0x1a, 0x2e, 0x6d, 0x65, 0x73, 0x73, 0x61, 0x67, 0x65, 0x73, 0x2e, 0x4e, 0x65,
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+	0x41, 0x6e, 0x6e, 0x6f, 0x75, 0x6e, 0x63, 0x65, 0x1a, 0x18, 0x2e, 0x6d, 0x65, 0x73, 0x73, 0x61,
+	0x67, 0x65, 0x73, 0x2e, 0x4f, 0x77, 0x6e, 0x65, 0x72, 0x43, 0x68, 0x61, 0x6e, 0x67, 0x65, 0x41,
+	0x63, 0x6b, 0x12, 0x44, 0x0a, 0x0e, 0x41, 0x6e, 0x6e, 0x6f, 0x75, 0x6e, 0x63, 0x65, 0x45, 0x78,
+	0x70, 0x69, 0x72, 0x79, 0x12, 0x18, 0x2e, 0x6d, 0x65, 0x73, 0x73, 0x61, 0x67, 0x65, 0x73, 0x2e,
+	0x45, 0x78, 0x70, 0x69, 0x72, 0x79, 0x41, 0x6e, 0x6e, 0x6f, 0x75, 0x6e, 0x63, 0x65, 0x1a, 0x18,
+	0x2e, 0x6d, 0x65, 0x73, 0x73, 0x61, 0x67, 0x65, 0x73, 0x2e, 0x4f, 0x77, 0x6e, 0x65, 0x72, 0x43,
+	0x68, 0x61, 0x6e, 0x67, 0x65, 0x41, 0x63, 0x6b, 0x12, 0x3c, 0x0a, 0x07, 0x43, 0x6c, 0x6f, 0x73,
+	0x69, 0x6e, 0x67, 0x12, 0x17, 0x2e, 0x6d, 0x65, 0x73, 0x73, 0x61, 0x67, 0x65, 0x73, 0x2e, 0x43,
+	0x6c, 0x6f, 0x73, 0x69, 0x6e, 0x67, 0x4e, 0x6f, 0x74, 0x69, 0x63, 0x65, 0x1a, 0x18, 0x2e, 0x6d,
+	0x65, 0x73, 0x73, 0x61, 0x67, 0x65, 0x73, 0x2e, 0x4f, 0x77, 0x6e, 0x65, 0x72, 0x43, 0x68, 0x61,
+	0x6e, 0x67, 0x65, 0x41, 0x63, 0x6b, 0x42, 0x2e, 0x5a, 0x2c, 0x67, 0x69, 0x74, 0x2e, 0x74, 0x6f,
+	0x72, 0x6e, 0x62, 0x65, 0x72, 0x67, 0x2e, 0x6d, 0x65, 0x2f, 0x67, 0x6f, 0x2d, 0x63, 0x61, 0x72,
+	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
@@ -442,30 +525,33 @@ func file_control_plane_proto_rawDescGZIP() []byte {
 	return file_control_plane_proto_rawDescData
 }
 
-var file_control_plane_proto_msgTypes = make([]protoimpl.MessageInfo, 8)
+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
-	(*CartIdsReply)(nil),       // 4: messages.CartIdsReply
+	(*ActorIdsReply)(nil),     // 4: messages.ActorIdsReply
-	(*OwnerChangeRequest)(nil), // 5: messages.OwnerChangeRequest
+	(*OwnerChangeAck)(nil),    // 5: messages.OwnerChangeAck
-	(*OwnerChangeAck)(nil),     // 6: messages.OwnerChangeAck
+	(*ClosingNotice)(nil),     // 6: messages.ClosingNotice
-	(*ClosingNotice)(nil),      // 7: 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.GetCartIds:input_type -> messages.Empty
+	0, // 2: messages.ControlPlane.GetLocalActorIds:input_type -> messages.Empty
-	5, // 3: messages.ControlPlane.ConfirmOwner:input_type -> messages.OwnerChangeRequest
+	7, // 3: messages.ControlPlane.AnnounceOwnership:input_type -> messages.OwnershipAnnounce
-	7, // 4: messages.ControlPlane.Closing:input_type -> messages.ClosingNotice
+	8, // 4: messages.ControlPlane.AnnounceExpiry:input_type -> messages.ExpiryAnnounce
-	1, // 5: messages.ControlPlane.Ping:output_type -> messages.PingReply
+	6, // 5: messages.ControlPlane.Closing:input_type -> messages.ClosingNotice
-	3, // 6: messages.ControlPlane.Negotiate:output_type -> messages.NegotiateReply
+	1, // 6: messages.ControlPlane.Ping:output_type -> messages.PingReply
-	4, // 7: messages.ControlPlane.GetCartIds:output_type -> messages.CartIdsReply
+	3, // 7: messages.ControlPlane.Negotiate:output_type -> messages.NegotiateReply
-	6, // 8: messages.ControlPlane.ConfirmOwner:output_type -> messages.OwnerChangeAck
+	4, // 8: messages.ControlPlane.GetLocalActorIds:output_type -> messages.ActorIdsReply
-	6, // 9: messages.ControlPlane.Closing:output_type -> messages.OwnerChangeAck
+	5, // 9: messages.ControlPlane.AnnounceOwnership:output_type -> messages.OwnerChangeAck
-	5, // [5:10] is the sub-list for method output_type
+	5, // 10: messages.ControlPlane.AnnounceExpiry:output_type -> messages.OwnerChangeAck
-	0, // [0:5] is the sub-list for method input_type
+	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
@@ -482,7 +568,7 @@ func file_control_plane_proto_init() {
 			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
 			RawDescriptor: unsafe.Slice(unsafe.StringData(file_control_plane_proto_rawDesc), len(file_control_plane_proto_rawDesc)),
 			NumEnums:      0,
-			NumMessages:   8,
+			NumMessages:   9,
 			NumExtensions: 0,
 			NumServices:   1,
 		},

pkg/messages/control_plane_grpc.pb.go

@@ -1,7 +1,7 @@
 // Code generated by protoc-gen-go-grpc. DO NOT EDIT.
 // versions:
 // - protoc-gen-go-grpc v1.5.1
-// - protoc             v3.21.12
+// - protoc             v5.29.3
 // source: control_plane.proto
 
 package messages
@@ -21,8 +21,9 @@ const _ = grpc.SupportPackageIsVersion9
 const (
 	ControlPlane_Ping_FullMethodName              = "/messages.ControlPlane/Ping"
 	ControlPlane_Negotiate_FullMethodName         = "/messages.ControlPlane/Negotiate"
-	ControlPlane_GetCartIds_FullMethodName   = "/messages.ControlPlane/GetCartIds"
+	ControlPlane_GetLocalActorIds_FullMethodName  = "/messages.ControlPlane/GetLocalActorIds"
-	ControlPlane_ConfirmOwner_FullMethodName = "/messages.ControlPlane/ConfirmOwner"
+	ControlPlane_AnnounceOwnership_FullMethodName = "/messages.ControlPlane/AnnounceOwnership"
+	ControlPlane_AnnounceExpiry_FullMethodName    = "/messages.ControlPlane/AnnounceExpiry"
 	ControlPlane_Closing_FullMethodName           = "/messages.ControlPlane/Closing"
 )
 
@@ -37,9 +38,11 @@ type ControlPlaneClient interface {
 	// 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.
-	GetCartIds(ctx context.Context, in *Empty, opts ...grpc.CallOption) (*CartIdsReply, error)
+	GetLocalActorIds(ctx context.Context, in *Empty, opts ...grpc.CallOption) (*ActorIdsReply, error)
-	// ConfirmOwner announces/asks peers to acknowledge ownership transfer.
+	// Ownership announcement: first-touch claim broadcast (idempotent; best-effort).
-	ConfirmOwner(ctx context.Context, in *OwnerChangeRequest, opts ...grpc.CallOption) (*OwnerChangeAck, error)
+	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)
 }
@@ -72,20 +75,30 @@ func (c *controlPlaneClient) Negotiate(ctx context.Context, in *NegotiateRequest
 	return out, nil
 }
 
-func (c *controlPlaneClient) GetCartIds(ctx context.Context, in *Empty, opts ...grpc.CallOption) (*CartIdsReply, error) {
+func (c *controlPlaneClient) GetLocalActorIds(ctx context.Context, in *Empty, opts ...grpc.CallOption) (*ActorIdsReply, error) {
 	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
-	out := new(CartIdsReply)
+	out := new(ActorIdsReply)
-	err := c.cc.Invoke(ctx, ControlPlane_GetCartIds_FullMethodName, in, out, cOpts...)
+	err := c.cc.Invoke(ctx, ControlPlane_GetLocalActorIds_FullMethodName, in, out, cOpts...)
 	if err != nil {
 		return nil, err
 	}
 	return out, nil
 }
 
-func (c *controlPlaneClient) ConfirmOwner(ctx context.Context, in *OwnerChangeRequest, opts ...grpc.CallOption) (*OwnerChangeAck, error) {
+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_ConfirmOwner_FullMethodName, in, out, cOpts...)
+	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
 	}
@@ -113,9 +126,11 @@ type ControlPlaneServer interface {
 	// Negotiate merges host views; used during discovery & convergence.
 	Negotiate(context.Context, *NegotiateRequest) (*NegotiateReply, error)
 	// GetCartIds lists currently owned cart IDs on this node.
-	GetCartIds(context.Context, *Empty) (*CartIdsReply, error)
+	GetLocalActorIds(context.Context, *Empty) (*ActorIdsReply, error)
-	// ConfirmOwner announces/asks peers to acknowledge ownership transfer.
+	// Ownership announcement: first-touch claim broadcast (idempotent; best-effort).
-	ConfirmOwner(context.Context, *OwnerChangeRequest) (*OwnerChangeAck, error)
+	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()
@@ -134,11 +149,14 @@ func (UnimplementedControlPlaneServer) Ping(context.Context, *Empty) (*PingReply
 func (UnimplementedControlPlaneServer) Negotiate(context.Context, *NegotiateRequest) (*NegotiateReply, error) {
 	return nil, status.Errorf(codes.Unimplemented, "method Negotiate not implemented")
 }
-func (UnimplementedControlPlaneServer) GetCartIds(context.Context, *Empty) (*CartIdsReply, error) {
+func (UnimplementedControlPlaneServer) GetLocalActorIds(context.Context, *Empty) (*ActorIdsReply, error) {
-	return nil, status.Errorf(codes.Unimplemented, "method GetCartIds not implemented")
+	return nil, status.Errorf(codes.Unimplemented, "method GetLocalActorIds not implemented")
 }
-func (UnimplementedControlPlaneServer) ConfirmOwner(context.Context, *OwnerChangeRequest) (*OwnerChangeAck, error) {
+func (UnimplementedControlPlaneServer) AnnounceOwnership(context.Context, *OwnershipAnnounce) (*OwnerChangeAck, error) {
-	return nil, status.Errorf(codes.Unimplemented, "method ConfirmOwner not implemented")
+	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")
@@ -200,38 +218,56 @@ func _ControlPlane_Negotiate_Handler(srv interface{}, ctx context.Context, dec f
 	return interceptor(ctx, in, info, handler)
 }
 
-func _ControlPlane_GetCartIds_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+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).GetCartIds(ctx, in)
+		return srv.(ControlPlaneServer).GetLocalActorIds(ctx, in)
 	}
 	info := &grpc.UnaryServerInfo{
 		Server:     srv,
-		FullMethod: ControlPlane_GetCartIds_FullMethodName,
+		FullMethod: ControlPlane_GetLocalActorIds_FullMethodName,
 	}
 	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
-		return srv.(ControlPlaneServer).GetCartIds(ctx, req.(*Empty))
+		return srv.(ControlPlaneServer).GetLocalActorIds(ctx, req.(*Empty))
 	}
 	return interceptor(ctx, in, info, handler)
 }
 
-func _ControlPlane_ConfirmOwner_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+func _ControlPlane_AnnounceOwnership_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
-	in := new(OwnerChangeRequest)
+	in := new(OwnershipAnnounce)
 	if err := dec(in); err != nil {
 		return nil, err
 	}
 	if interceptor == nil {
-		return srv.(ControlPlaneServer).ConfirmOwner(ctx, in)
+		return srv.(ControlPlaneServer).AnnounceOwnership(ctx, in)
 	}
 	info := &grpc.UnaryServerInfo{
 		Server:     srv,
-		FullMethod: ControlPlane_ConfirmOwner_FullMethodName,
+		FullMethod: ControlPlane_AnnounceOwnership_FullMethodName,
 	}
 	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
-		return srv.(ControlPlaneServer).ConfirmOwner(ctx, req.(*OwnerChangeRequest))
+		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)
 }
@@ -270,12 +306,16 @@ var ControlPlane_ServiceDesc = grpc.ServiceDesc{
 			Handler:    _ControlPlane_Negotiate_Handler,
 		},
 		{
-			MethodName: "GetCartIds",
+			MethodName: "GetLocalActorIds",
-			Handler:    _ControlPlane_GetCartIds_Handler,
+			Handler:    _ControlPlane_GetLocalActorIds_Handler,
 		},
 		{
-			MethodName: "ConfirmOwner",
+			MethodName: "AnnounceOwnership",
-			Handler:    _ControlPlane_ConfirmOwner_Handler,
+			Handler:    _ControlPlane_AnnounceOwnership_Handler,
+		},
+		{
+			MethodName: "AnnounceExpiry",
+			Handler:    _ControlPlane_AnnounceExpiry_Handler,
 		},
 		{
 			MethodName: "Closing",

pkg/proxy/remotehost.go

@@ -0,0 +1,187 @@
+package proxy
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"io"
+	"log"
+	"net/http"
+	"time"
+
+	messages "git.tornberg.me/go-cart-actor/pkg/messages"
+	"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
+}
+
+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/cart", 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())
+
+	req, err := http.NewRequestWithContext(r.Context(), r.Method, target, r.Body)
+	if err != nil {
+		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 {
+		http.Error(w, "proxy request error", http.StatusBadGateway)
+		return false, err
+	}
+	defer res.Body.Close()
+	for k, v := range res.Header {
+		for _, vv := range v {
+			w.Header().Add(k, vv)
+		}
+	}
+	w.Header().Set("X-Cart-Owner-Routed", "true")
+	if res.StatusCode >= 200 && res.StatusCode <= 299 {
+		w.WriteHeader(res.StatusCode)
+		_, copyErr := io.Copy(w, res.Body)
+		if copyErr != nil {
+			return true, copyErr
+		}
+		return true, nil
+	}
+	return false, fmt.Errorf("proxy response status %d", res.StatusCode)
+}
+
+func (r *RemoteHost) IsHealthy() bool {
+	return r.missedPings < 3
+}

pkg/voucher/parser.go

@@ -0,0 +1,347 @@
+package voucher
+
+import (
+	"errors"
+	"fmt"
+	"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 {
+	for _, it := range items {
+		if pred(it) {
+			return true
+		}
+	}
+	return false
+}
+
+// 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 +1,179 @@
+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 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 +1,39 @@
+package voucher
+
+import (
+	"errors"
+
+	"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:"discount"`
+	TaxValue int64  `json:"taxValue"`
+	TaxRate  int    `json:"taxRate"`
+	rules    []Rule `json:"rules"`
+}
+
+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
+	}
+	value := int64(250_00)
+	return &messages.AddVoucher{
+		Code:         code,
+		Value:        value,
+		VoucherRules: make([]*messages.VoucherRule, 0),
+	}, 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
-}

product-fetcher.go

@@ -1,35 +0,0 @@
-package main
-
-import (
-	"encoding/json"
-	"fmt"
-	"net/http"
-
-	"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(sku string, country string) (*index.DataItem, error) {
-	baseUrl := getBaseUrl(country)
-	res, err := http.Get(fmt.Sprintf("%s/api/by-sku/%s", baseUrl, sku))
-	if err != nil {
-		return nil, err
-	}
-	defer res.Body.Close()
-	var item index.DataItem
-	err = json.NewDecoder(res.Body).Decode(&item)
-	return &item, err
-}

proto/cart_actor.pb.go

@@ -1,420 +0,0 @@
-// Code generated by protoc-gen-go. DO NOT EDIT.
-// versions:
-// 	protoc-gen-go v1.36.10
-// 	protoc        v3.21.12
-// source: cart_actor.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)
-)
-
-// MutationType corresponds 1:1 with the legacy uint16 message type constants.
-type MutationType int32
-
-const (
-	MutationType_MUTATION_TYPE_UNSPECIFIED MutationType = 0
-	MutationType_MUTATION_ADD_REQUEST      MutationType = 1
-	MutationType_MUTATION_ADD_ITEM         MutationType = 2
-	// (3 was unused / reserved in legacy framing)
-	MutationType_MUTATION_REMOVE_ITEM           MutationType = 4
-	MutationType_MUTATION_REMOVE_DELIVERY       MutationType = 5
-	MutationType_MUTATION_CHANGE_QUANTITY       MutationType = 6
-	MutationType_MUTATION_SET_DELIVERY          MutationType = 7
-	MutationType_MUTATION_SET_PICKUP_POINT      MutationType = 8
-	MutationType_MUTATION_CREATE_CHECKOUT_ORDER MutationType = 9
-	MutationType_MUTATION_SET_CART_ITEMS        MutationType = 10
-	MutationType_MUTATION_ORDER_COMPLETED       MutationType = 11
-)
-
-// Enum value maps for MutationType.
-var (
-	MutationType_name = map[int32]string{
-		0:  "MUTATION_TYPE_UNSPECIFIED",
-		1:  "MUTATION_ADD_REQUEST",
-		2:  "MUTATION_ADD_ITEM",
-		4:  "MUTATION_REMOVE_ITEM",
-		5:  "MUTATION_REMOVE_DELIVERY",
-		6:  "MUTATION_CHANGE_QUANTITY",
-		7:  "MUTATION_SET_DELIVERY",
-		8:  "MUTATION_SET_PICKUP_POINT",
-		9:  "MUTATION_CREATE_CHECKOUT_ORDER",
-		10: "MUTATION_SET_CART_ITEMS",
-		11: "MUTATION_ORDER_COMPLETED",
-	}
-	MutationType_value = map[string]int32{
-		"MUTATION_TYPE_UNSPECIFIED":      0,
-		"MUTATION_ADD_REQUEST":           1,
-		"MUTATION_ADD_ITEM":              2,
-		"MUTATION_REMOVE_ITEM":           4,
-		"MUTATION_REMOVE_DELIVERY":       5,
-		"MUTATION_CHANGE_QUANTITY":       6,
-		"MUTATION_SET_DELIVERY":          7,
-		"MUTATION_SET_PICKUP_POINT":      8,
-		"MUTATION_CREATE_CHECKOUT_ORDER": 9,
-		"MUTATION_SET_CART_ITEMS":        10,
-		"MUTATION_ORDER_COMPLETED":       11,
-	}
-)
-
-func (x MutationType) Enum() *MutationType {
-	p := new(MutationType)
-	*p = x
-	return p
-}
-
-func (x MutationType) String() string {
-	return protoimpl.X.EnumStringOf(x.Descriptor(), protoreflect.EnumNumber(x))
-}
-
-func (MutationType) Descriptor() protoreflect.EnumDescriptor {
-	return file_cart_actor_proto_enumTypes[0].Descriptor()
-}
-
-func (MutationType) Type() protoreflect.EnumType {
-	return &file_cart_actor_proto_enumTypes[0]
-}
-
-func (x MutationType) Number() protoreflect.EnumNumber {
-	return protoreflect.EnumNumber(x)
-}
-
-// Deprecated: Use MutationType.Descriptor instead.
-func (MutationType) EnumDescriptor() ([]byte, []int) {
-	return file_cart_actor_proto_rawDescGZIP(), []int{0}
-}
-
-// MutationRequest is an envelope:
-// - cart_id: string form of CartId (legacy 16-byte array truncated/padded).
-// - type: mutation kind (see enum).
-// - payload: serialized underlying proto message (AddRequest, AddItem, etc.).
-// - client_timestamp: optional unix timestamp; server sets if zero.
-type MutationRequest struct {
-	state           protoimpl.MessageState `protogen:"open.v1"`
-	CartId          string                 `protobuf:"bytes,1,opt,name=cart_id,json=cartId,proto3" json:"cart_id,omitempty"`
-	Type            MutationType           `protobuf:"varint,2,opt,name=type,proto3,enum=messages.MutationType" json:"type,omitempty"`
-	Payload         []byte                 `protobuf:"bytes,3,opt,name=payload,proto3" json:"payload,omitempty"`
-	ClientTimestamp int64                  `protobuf:"varint,4,opt,name=client_timestamp,json=clientTimestamp,proto3" json:"client_timestamp,omitempty"`
-	unknownFields   protoimpl.UnknownFields
-	sizeCache       protoimpl.SizeCache
-}
-
-func (x *MutationRequest) Reset() {
-	*x = MutationRequest{}
-	mi := &file_cart_actor_proto_msgTypes[0]
-	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
-	ms.StoreMessageInfo(mi)
-}
-
-func (x *MutationRequest) String() string {
-	return protoimpl.X.MessageStringOf(x)
-}
-
-func (*MutationRequest) ProtoMessage() {}
-
-func (x *MutationRequest) ProtoReflect() protoreflect.Message {
-	mi := &file_cart_actor_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 MutationRequest.ProtoReflect.Descriptor instead.
-func (*MutationRequest) Descriptor() ([]byte, []int) {
-	return file_cart_actor_proto_rawDescGZIP(), []int{0}
-}
-
-func (x *MutationRequest) GetCartId() string {
-	if x != nil {
-		return x.CartId
-	}
-	return ""
-}
-
-func (x *MutationRequest) GetType() MutationType {
-	if x != nil {
-		return x.Type
-	}
-	return MutationType_MUTATION_TYPE_UNSPECIFIED
-}
-
-func (x *MutationRequest) GetPayload() []byte {
-	if x != nil {
-		return x.Payload
-	}
-	return nil
-}
-
-func (x *MutationRequest) GetClientTimestamp() int64 {
-	if x != nil {
-		return x.ClientTimestamp
-	}
-	return 0
-}
-
-// MutationReply returns a status code (legacy semantics) plus a JSON payload
-// representing the full cart state (or an error message if non-200).
-type MutationReply struct {
-	state         protoimpl.MessageState `protogen:"open.v1"`
-	StatusCode    int32                  `protobuf:"varint,1,opt,name=status_code,json=statusCode,proto3" json:"status_code,omitempty"`
-	Payload       []byte                 `protobuf:"bytes,2,opt,name=payload,proto3" json:"payload,omitempty"` // JSON cart state or error string
-	unknownFields protoimpl.UnknownFields
-	sizeCache     protoimpl.SizeCache
-}
-
-func (x *MutationReply) Reset() {
-	*x = MutationReply{}
-	mi := &file_cart_actor_proto_msgTypes[1]
-	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
-	ms.StoreMessageInfo(mi)
-}
-
-func (x *MutationReply) String() string {
-	return protoimpl.X.MessageStringOf(x)
-}
-
-func (*MutationReply) ProtoMessage() {}
-
-func (x *MutationReply) ProtoReflect() protoreflect.Message {
-	mi := &file_cart_actor_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 MutationReply.ProtoReflect.Descriptor instead.
-func (*MutationReply) Descriptor() ([]byte, []int) {
-	return file_cart_actor_proto_rawDescGZIP(), []int{1}
-}
-
-func (x *MutationReply) GetStatusCode() int32 {
-	if x != nil {
-		return x.StatusCode
-	}
-	return 0
-}
-
-func (x *MutationReply) GetPayload() []byte {
-	if x != nil {
-		return x.Payload
-	}
-	return nil
-}
-
-// StateRequest fetches current cart state without mutation.
-type StateRequest struct {
-	state         protoimpl.MessageState `protogen:"open.v1"`
-	CartId        string                 `protobuf:"bytes,1,opt,name=cart_id,json=cartId,proto3" json:"cart_id,omitempty"`
-	unknownFields protoimpl.UnknownFields
-	sizeCache     protoimpl.SizeCache
-}
-
-func (x *StateRequest) Reset() {
-	*x = StateRequest{}
-	mi := &file_cart_actor_proto_msgTypes[2]
-	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
-	ms.StoreMessageInfo(mi)
-}
-
-func (x *StateRequest) String() string {
-	return protoimpl.X.MessageStringOf(x)
-}
-
-func (*StateRequest) ProtoMessage() {}
-
-func (x *StateRequest) ProtoReflect() protoreflect.Message {
-	mi := &file_cart_actor_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 StateRequest.ProtoReflect.Descriptor instead.
-func (*StateRequest) Descriptor() ([]byte, []int) {
-	return file_cart_actor_proto_rawDescGZIP(), []int{2}
-}
-
-func (x *StateRequest) GetCartId() string {
-	if x != nil {
-		return x.CartId
-	}
-	return ""
-}
-
-// StateReply mirrors MutationReply for consistency.
-type StateReply struct {
-	state         protoimpl.MessageState `protogen:"open.v1"`
-	StatusCode    int32                  `protobuf:"varint,1,opt,name=status_code,json=statusCode,proto3" json:"status_code,omitempty"`
-	Payload       []byte                 `protobuf:"bytes,2,opt,name=payload,proto3" json:"payload,omitempty"` // JSON cart state or error string
-	unknownFields protoimpl.UnknownFields
-	sizeCache     protoimpl.SizeCache
-}
-
-func (x *StateReply) Reset() {
-	*x = StateReply{}
-	mi := &file_cart_actor_proto_msgTypes[3]
-	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
-	ms.StoreMessageInfo(mi)
-}
-
-func (x *StateReply) String() string {
-	return protoimpl.X.MessageStringOf(x)
-}
-
-func (*StateReply) ProtoMessage() {}
-
-func (x *StateReply) ProtoReflect() protoreflect.Message {
-	mi := &file_cart_actor_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 StateReply.ProtoReflect.Descriptor instead.
-func (*StateReply) Descriptor() ([]byte, []int) {
-	return file_cart_actor_proto_rawDescGZIP(), []int{3}
-}
-
-func (x *StateReply) GetStatusCode() int32 {
-	if x != nil {
-		return x.StatusCode
-	}
-	return 0
-}
-
-func (x *StateReply) GetPayload() []byte {
-	if x != nil {
-		return x.Payload
-	}
-	return nil
-}
-
-var File_cart_actor_proto protoreflect.FileDescriptor
-
-const file_cart_actor_proto_rawDesc = "" +
-	"\n" +
-	"\x10cart_actor.proto\x12\bmessages\"\x9b\x01\n" +
-	"\x0fMutationRequest\x12\x17\n" +
-	"\acart_id\x18\x01 \x01(\tR\x06cartId\x12*\n" +
-	"\x04type\x18\x02 \x01(\x0e2\x16.messages.MutationTypeR\x04type\x12\x18\n" +
-	"\apayload\x18\x03 \x01(\fR\apayload\x12)\n" +
-	"\x10client_timestamp\x18\x04 \x01(\x03R\x0fclientTimestamp\"J\n" +
-	"\rMutationReply\x12\x1f\n" +
-	"\vstatus_code\x18\x01 \x01(\x05R\n" +
-	"statusCode\x12\x18\n" +
-	"\apayload\x18\x02 \x01(\fR\apayload\"'\n" +
-	"\fStateRequest\x12\x17\n" +
-	"\acart_id\x18\x01 \x01(\tR\x06cartId\"G\n" +
-	"\n" +
-	"StateReply\x12\x1f\n" +
-	"\vstatus_code\x18\x01 \x01(\x05R\n" +
-	"statusCode\x12\x18\n" +
-	"\apayload\x18\x02 \x01(\fR\apayload*\xcd\x02\n" +
-	"\fMutationType\x12\x1d\n" +
-	"\x19MUTATION_TYPE_UNSPECIFIED\x10\x00\x12\x18\n" +
-	"\x14MUTATION_ADD_REQUEST\x10\x01\x12\x15\n" +
-	"\x11MUTATION_ADD_ITEM\x10\x02\x12\x18\n" +
-	"\x14MUTATION_REMOVE_ITEM\x10\x04\x12\x1c\n" +
-	"\x18MUTATION_REMOVE_DELIVERY\x10\x05\x12\x1c\n" +
-	"\x18MUTATION_CHANGE_QUANTITY\x10\x06\x12\x19\n" +
-	"\x15MUTATION_SET_DELIVERY\x10\a\x12\x1d\n" +
-	"\x19MUTATION_SET_PICKUP_POINT\x10\b\x12\"\n" +
-	"\x1eMUTATION_CREATE_CHECKOUT_ORDER\x10\t\x12\x1b\n" +
-	"\x17MUTATION_SET_CART_ITEMS\x10\n" +
-	"\x12\x1c\n" +
-	"\x18MUTATION_ORDER_COMPLETED\x10\v2\x83\x01\n" +
-	"\tCartActor\x12<\n" +
-	"\x06Mutate\x12\x19.messages.MutationRequest\x1a\x17.messages.MutationReply\x128\n" +
-	"\bGetState\x12\x16.messages.StateRequest\x1a\x14.messages.StateReplyB\fZ\n" +
-	".;messagesb\x06proto3"
-
-var (
-	file_cart_actor_proto_rawDescOnce sync.Once
-	file_cart_actor_proto_rawDescData []byte
-)
-
-func file_cart_actor_proto_rawDescGZIP() []byte {
-	file_cart_actor_proto_rawDescOnce.Do(func() {
-		file_cart_actor_proto_rawDescData = protoimpl.X.CompressGZIP(unsafe.Slice(unsafe.StringData(file_cart_actor_proto_rawDesc), len(file_cart_actor_proto_rawDesc)))
-	})
-	return file_cart_actor_proto_rawDescData
-}
-
-var file_cart_actor_proto_enumTypes = make([]protoimpl.EnumInfo, 1)
-var file_cart_actor_proto_msgTypes = make([]protoimpl.MessageInfo, 4)
-var file_cart_actor_proto_goTypes = []any{
-	(MutationType)(0),       // 0: messages.MutationType
-	(*MutationRequest)(nil), // 1: messages.MutationRequest
-	(*MutationReply)(nil),   // 2: messages.MutationReply
-	(*StateRequest)(nil),    // 3: messages.StateRequest
-	(*StateReply)(nil),      // 4: messages.StateReply
-}
-var file_cart_actor_proto_depIdxs = []int32{
-	0, // 0: messages.MutationRequest.type:type_name -> messages.MutationType
-	1, // 1: messages.CartActor.Mutate:input_type -> messages.MutationRequest
-	3, // 2: messages.CartActor.GetState:input_type -> messages.StateRequest
-	2, // 3: messages.CartActor.Mutate:output_type -> messages.MutationReply
-	4, // 4: messages.CartActor.GetState:output_type -> messages.StateReply
-	3, // [3:5] is the sub-list for method output_type
-	1, // [1:3] is the sub-list for method input_type
-	1, // [1:1] is the sub-list for extension type_name
-	1, // [1:1] is the sub-list for extension extendee
-	0, // [0:1] is the sub-list for field type_name
-}
-
-func init() { file_cart_actor_proto_init() }
-func file_cart_actor_proto_init() {
-	if File_cart_actor_proto != nil {
-		return
-	}
-	type x struct{}
-	out := protoimpl.TypeBuilder{
-		File: protoimpl.DescBuilder{
-			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
-			RawDescriptor: unsafe.Slice(unsafe.StringData(file_cart_actor_proto_rawDesc), len(file_cart_actor_proto_rawDesc)),
-			NumEnums:      1,
-			NumMessages:   4,
-			NumExtensions: 0,
-			NumServices:   1,
-		},
-		GoTypes:           file_cart_actor_proto_goTypes,
-		DependencyIndexes: file_cart_actor_proto_depIdxs,
-		EnumInfos:         file_cart_actor_proto_enumTypes,
-		MessageInfos:      file_cart_actor_proto_msgTypes,
-	}.Build()
-	File_cart_actor_proto = out.File
-	file_cart_actor_proto_goTypes = nil
-	file_cart_actor_proto_depIdxs = nil
-}

proto/cart_actor.proto

@@ -1,89 +0,0 @@
-syntax = "proto3";
-
-package messages;
-
-option go_package = ".;messages";
-
-// -----------------------------------------------------------------------------
-// Cart Actor gRPC API (Envelope Variant)
-// -----------------------------------------------------------------------------
-// This service replaces the legacy custom TCP frame protocol used on port 1337.
-// It keeps the existing per-mutation proto messages (defined in messages.proto)
-// serialized into an opaque `bytes payload` field for minimal refactor cost.
-// The numeric values in MutationType MUST match the legacy message type
-// constants (see message-types.go) so persisted event logs replay correctly.
-// -----------------------------------------------------------------------------
-
-// MutationType corresponds 1:1 with the legacy uint16 message type constants.
-enum MutationType {
-  MUTATION_TYPE_UNSPECIFIED        = 0;
-  MUTATION_ADD_REQUEST             = 1;
-  MUTATION_ADD_ITEM                = 2;
-  // (3 was unused / reserved in legacy framing)
-  MUTATION_REMOVE_ITEM             = 4;
-  MUTATION_REMOVE_DELIVERY         = 5;
-  MUTATION_CHANGE_QUANTITY         = 6;
-  MUTATION_SET_DELIVERY            = 7;
-  MUTATION_SET_PICKUP_POINT        = 8;
-  MUTATION_CREATE_CHECKOUT_ORDER   = 9;
-  MUTATION_SET_CART_ITEMS          = 10;
-  MUTATION_ORDER_COMPLETED         = 11;
-}
-
-// MutationRequest is an envelope:
-// - cart_id: string form of CartId (legacy 16-byte array truncated/padded).
-// - type: mutation kind (see enum).
-// - payload: serialized underlying proto message (AddRequest, AddItem, etc.).
-// - client_timestamp: optional unix timestamp; server sets if zero.
-message MutationRequest {
-  string cart_id        = 1;
-  MutationType type     = 2;
-  bytes payload         = 3;
-  int64 client_timestamp = 4;
-}
-
-// MutationReply returns a status code (legacy semantics) plus a JSON payload
-// representing the full cart state (or an error message if non-200).
-message MutationReply {
-  int32 status_code = 1;
-  bytes payload     = 2; // JSON cart state or error string
-}
-
-// StateRequest fetches current cart state without mutation.
-message StateRequest {
-  string cart_id = 1;
-}
-
-// StateReply mirrors MutationReply for consistency.
-message StateReply {
-  int32 status_code = 1;
-  bytes payload     = 2; // JSON cart state or error string
-}
-
-// CartActor exposes mutation and state retrieval for remote grains.
-service CartActor {
-  // Mutate applies a single mutation to a cart, creating the cart lazily if needed.
-  rpc Mutate(MutationRequest) returns (MutationReply);
-
-  // GetState retrieves the cart's current state (JSON).
-  rpc GetState(StateRequest) returns (StateReply);
-}
-
-// -----------------------------------------------------------------------------
-// Notes:
-//
-// 1. Generation:
-//    protoc --go_out=. --go_opt=paths=source_relative \
-//           --go-grpc_out=. --go-grpc_opt=paths=source_relative \
-//           cart_actor.proto
-//
-// 2. Underlying mutation payloads originate from messages.proto definitions.
-//    The server side will route based on MutationType and decode payload bytes
-//    using existing handler registry logic.
-//
-// 3. Future Enhancements:
-//    - Replace JSON state payload with a strongly typed CartState proto.
-//    - Add streaming RPC (e.g. WatchState) for live updates.
-//    - Migrate control plane (negotiate/ownership) into a separate proto
-//      (control_plane.proto) as per the migration plan.
-// -----------------------------------------------------------------------------

proto/cart_actor_grpc.pb.go

@@ -1,167 +0,0 @@
-// Code generated by protoc-gen-go-grpc. DO NOT EDIT.
-// versions:
-// - protoc-gen-go-grpc v1.5.1
-// - protoc             v3.21.12
-// source: cart_actor.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 (
-	CartActor_Mutate_FullMethodName   = "/messages.CartActor/Mutate"
-	CartActor_GetState_FullMethodName = "/messages.CartActor/GetState"
-)
-
-// CartActorClient is the client API for CartActor 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.
-//
-// CartActor exposes mutation and state retrieval for remote grains.
-type CartActorClient interface {
-	// Mutate applies a single mutation to a cart, creating the cart lazily if needed.
-	Mutate(ctx context.Context, in *MutationRequest, opts ...grpc.CallOption) (*MutationReply, error)
-	// GetState retrieves the cart's current state (JSON).
-	GetState(ctx context.Context, in *StateRequest, opts ...grpc.CallOption) (*StateReply, error)
-}
-
-type cartActorClient struct {
-	cc grpc.ClientConnInterface
-}
-
-func NewCartActorClient(cc grpc.ClientConnInterface) CartActorClient {
-	return &cartActorClient{cc}
-}
-
-func (c *cartActorClient) Mutate(ctx context.Context, in *MutationRequest, opts ...grpc.CallOption) (*MutationReply, error) {
-	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
-	out := new(MutationReply)
-	err := c.cc.Invoke(ctx, CartActor_Mutate_FullMethodName, in, out, cOpts...)
-	if err != nil {
-		return nil, err
-	}
-	return out, nil
-}
-
-func (c *cartActorClient) GetState(ctx context.Context, in *StateRequest, opts ...grpc.CallOption) (*StateReply, error) {
-	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
-	out := new(StateReply)
-	err := c.cc.Invoke(ctx, CartActor_GetState_FullMethodName, in, out, cOpts...)
-	if err != nil {
-		return nil, err
-	}
-	return out, nil
-}
-
-// CartActorServer is the server API for CartActor service.
-// All implementations must embed UnimplementedCartActorServer
-// for forward compatibility.
-//
-// CartActor exposes mutation and state retrieval for remote grains.
-type CartActorServer interface {
-	// Mutate applies a single mutation to a cart, creating the cart lazily if needed.
-	Mutate(context.Context, *MutationRequest) (*MutationReply, error)
-	// GetState retrieves the cart's current state (JSON).
-	GetState(context.Context, *StateRequest) (*StateReply, error)
-	mustEmbedUnimplementedCartActorServer()
-}
-
-// UnimplementedCartActorServer 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 UnimplementedCartActorServer struct{}
-
-func (UnimplementedCartActorServer) Mutate(context.Context, *MutationRequest) (*MutationReply, error) {
-	return nil, status.Errorf(codes.Unimplemented, "method Mutate not implemented")
-}
-func (UnimplementedCartActorServer) GetState(context.Context, *StateRequest) (*StateReply, error) {
-	return nil, status.Errorf(codes.Unimplemented, "method GetState not implemented")
-}
-func (UnimplementedCartActorServer) mustEmbedUnimplementedCartActorServer() {}
-func (UnimplementedCartActorServer) testEmbeddedByValue()                   {}
-
-// UnsafeCartActorServer may be embedded to opt out of forward compatibility for this service.
-// Use of this interface is not recommended, as added methods to CartActorServer will
-// result in compilation errors.
-type UnsafeCartActorServer interface {
-	mustEmbedUnimplementedCartActorServer()
-}
-
-func RegisterCartActorServer(s grpc.ServiceRegistrar, srv CartActorServer) {
-	// If the following call pancis, it indicates UnimplementedCartActorServer 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(&CartActor_ServiceDesc, srv)
-}
-
-func _CartActor_Mutate_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
-	in := new(MutationRequest)
-	if err := dec(in); err != nil {
-		return nil, err
-	}
-	if interceptor == nil {
-		return srv.(CartActorServer).Mutate(ctx, in)
-	}
-	info := &grpc.UnaryServerInfo{
-		Server:     srv,
-		FullMethod: CartActor_Mutate_FullMethodName,
-	}
-	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
-		return srv.(CartActorServer).Mutate(ctx, req.(*MutationRequest))
-	}
-	return interceptor(ctx, in, info, handler)
-}
-
-func _CartActor_GetState_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
-	in := new(StateRequest)
-	if err := dec(in); err != nil {
-		return nil, err
-	}
-	if interceptor == nil {
-		return srv.(CartActorServer).GetState(ctx, in)
-	}
-	info := &grpc.UnaryServerInfo{
-		Server:     srv,
-		FullMethod: CartActor_GetState_FullMethodName,
-	}
-	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
-		return srv.(CartActorServer).GetState(ctx, req.(*StateRequest))
-	}
-	return interceptor(ctx, in, info, handler)
-}
-
-// CartActor_ServiceDesc is the grpc.ServiceDesc for CartActor service.
-// It's only intended for direct use with grpc.RegisterService,
-// and not to be introspected or modified (even as a copy)
-var CartActor_ServiceDesc = grpc.ServiceDesc{
-	ServiceName: "messages.CartActor",
-	HandlerType: (*CartActorServer)(nil),
-	Methods: []grpc.MethodDesc{
-		{
-			MethodName: "Mutate",
-			Handler:    _CartActor_Mutate_Handler,
-		},
-		{
-			MethodName: "GetState",
-			Handler:    _CartActor_GetState_Handler,
-		},
-	},
-	Streams:  []grpc.StreamDesc{},
-	Metadata: "cart_actor.proto",
-}

proto/control_plane.proto

@@ -2,7 +2,7 @@ syntax = "proto3";
 
 package messages;
 
-option go_package = ".;messages";
+option go_package = "git.tornberg.me/go-cart-actor/proto;messages";
 
 // -----------------------------------------------------------------------------
 // Control Plane gRPC API
@@ -11,8 +11,8 @@ option go_package = ".;messages";
 // Responsibilities:
 //   - Liveness (Ping)
 //   - Membership negotiation (Negotiate)
-//   - Cart ownership change propagation (ConfirmOwner)
+//   - Deterministic ring-based ownership (ConfirmOwner RPC removed)
-//   - Cart ID listing for remote grain spawning (GetCartIds)
+//   - Actor ID listing for remote grain spawning (GetActorIds)
 //   - Graceful shutdown notifications (Closing)
 // No authentication / TLS is defined initially (can be added later).
 // -----------------------------------------------------------------------------
@@ -37,17 +37,11 @@ message NegotiateReply {
 }
 
 // CartIdsReply returns the list of cart IDs (string form) currently owned locally.
-message CartIdsReply {
+message ActorIdsReply {
-  repeated string cart_ids = 1;
+  repeated uint64 ids = 1;
 }
 
-// OwnerChangeRequest notifies peers that ownership of a cart moved (or is moving) to new_host.
+// OwnerChangeAck retained as response type for Closing RPC (ConfirmOwner removed).
-message OwnerChangeRequest {
-  string cart_id = 1;
-  string new_host = 2;
-}
-
-// OwnerChangeAck indicates acceptance or rejection of an ownership change.
 message OwnerChangeAck {
   bool accepted = 1;
   string message = 2;
@@ -58,6 +52,19 @@ message ClosingNotice {
   string host = 1;
 }
 
+// OwnershipAnnounce broadcasts first-touch ownership claims for cart IDs.
+// First claim wins; receivers SHOULD NOT overwrite an existing different owner.
+message OwnershipAnnounce {
+  string host = 1;               // announcing host
+  repeated uint64 ids = 2;   // newly claimed cart ids
+}
+
+// ExpiryAnnounce broadcasts that a host evicted the provided cart IDs.
+message ExpiryAnnounce {
+  string host = 1;
+  repeated uint64 ids = 2;
+}
+
 // ControlPlane defines cluster coordination and ownership operations.
 service ControlPlane {
   // Ping for liveness; lightweight health signal.
@@ -67,10 +74,15 @@ service ControlPlane {
   rpc Negotiate(NegotiateRequest) returns (NegotiateReply);
 
   // GetCartIds lists currently owned cart IDs on this node.
-  rpc GetCartIds(Empty) returns (CartIdsReply);
+  rpc GetLocalActorIds(Empty) returns (ActorIdsReply);
 
-  // ConfirmOwner announces/asks peers to acknowledge ownership transfer.
+  // ConfirmOwner RPC removed (was legacy ownership acknowledgement; ring-based ownership now authoritative)
-  rpc ConfirmOwner(OwnerChangeRequest) returns (OwnerChangeAck);
+
+  // Ownership announcement: first-touch claim broadcast (idempotent; best-effort).
+  rpc AnnounceOwnership(OwnershipAnnounce) returns (OwnerChangeAck);
+
+  // Expiry announcement: drop remote ownership hints when local TTL expires.
+  rpc AnnounceExpiry(ExpiryAnnounce) returns (OwnerChangeAck);
 
   // Closing announces graceful shutdown so peers can proactively adjust.
   rpc Closing(ClosingNotice) returns (OwnerChangeAck);

proto/messages.proto

@@ -1,20 +1,13 @@
 syntax = "proto3";
 package messages;
-option go_package = ".;messages";
+option go_package = "git.tornberg.me/go-cart-actor/proto;messages";
 
-message AddRequest {
+message ClearCartRequest {
-		int32 quantity = 1;
-		string sku = 2;
-		string country = 3;
-		optional string storeId = 4;
-}
 
-message SetCartRequest {
-		repeated AddRequest items = 1;
 }
 
 message AddItem {
-		int64 item_id = 1;
+	uint32 item_id = 1;
 	int32 quantity = 2;
 	int64 price = 3;
 	int64 orgPrice = 9;
@@ -36,20 +29,21 @@ message AddItem {
 	string country = 21;
 	optional string outlet = 12;
 	optional string storeId = 22;
+	optional uint32 parentId = 23;
 }
 
 message RemoveItem {
-		int64 Id = 1;
+	uint32 Id = 1;
 }
 
 message ChangeQuantity {
-		int64 id = 1;
+    uint32 Id = 1;
 	int32 quantity = 2;
 }
 
 message SetDelivery {
 	string provider = 1;
-		repeated int64 items = 2;
+	repeated uint32 items = 2;
 	optional PickupPoint pickupPoint = 3;
 	string country = 4;
 	string zip = 5;
@@ -58,7 +52,7 @@ message SetDelivery {
 }
 
 message SetPickupPoint {
-        int64 deliveryId = 1;
+	uint32 deliveryId = 1;
 	string id = 2;
 	optional string name = 3;
 	optional string address = 4;
@@ -77,7 +71,7 @@ message PickupPoint {
 }
 
 message RemoveDelivery {
-		int64 id = 1;
+	uint32 id = 1;
 }
 
 message CreateCheckoutOrder {
@@ -93,3 +87,30 @@ message OrderCreated {
 	string orderId = 1;
 	string status = 2;
 }
+
+message Noop {
+	// Intentionally empty - used for ownership acquisition or health pings
+}
+
+message InitializeCheckout {
+	string orderId = 1;
+	string status = 2;
+	bool paymentInProgress = 3;
+}
+
+message VoucherRule {
+	string type = 2;
+	string description = 3;
+	string condition = 4;
+	string action = 5;
+}
+
+message AddVoucher {
+    string code = 1;
+    int64 value = 2;
+    repeated VoucherRule voucherRules = 3;
+}
+
+message RemoveVoucher {
+    uint32 id = 1;
+}

remote-grain-pool._go

@@ -1,67 +0,0 @@
-// package main
-
-// import "sync"
-
-// type RemoteGrainPool struct {
-// 	mu     sync.RWMutex
-// 	Host   string
-// 	grains map[CartId]*RemoteGrain
-// }
-
-// func NewRemoteGrainPool(addr string) *RemoteGrainPool {
-// 	return &RemoteGrainPool{
-// 		Host:   addr,
-// 		grains: make(map[CartId]*RemoteGrain),
-// 	}
-// }
-
-// func (p *RemoteGrainPool) findRemoteGrain(id CartId) *RemoteGrain {
-// 	p.mu.RLock()
-// 	grain, ok := p.grains[id]
-// 	p.mu.RUnlock()
-// 	if !ok {
-// 		return nil
-// 	}
-// 	return grain
-// }
-
-// func (p *RemoteGrainPool) findOrCreateGrain(id CartId) (*RemoteGrain, error) {
-// 	grain := p.findRemoteGrain(id)
-
-// 	if grain == nil {
-// 		grain, err := NewRemoteGrain(id, p.Host)
-// 		if err != nil {
-// 			return nil, err
-// 		}
-// 		p.mu.Lock()
-// 		p.grains[id] = grain
-// 		p.mu.Unlock()
-// 	}
-// 	return grain, nil
-// }
-
-// func (p *RemoteGrainPool) Delete(id CartId) {
-// 	p.mu.Lock()
-// 	delete(p.grains, id)
-// 	p.mu.Unlock()
-// }
-
-// func (p *RemoteGrainPool) Process(id CartId, messages ...Message) (*FrameWithPayload, error) {
-// 	var result *FrameWithPayload
-// 	grain, err := p.findOrCreateGrain(id)
-// 	if err != nil {
-// 		return nil, err
-// 	}
-// 	for _, message := range messages {
-// 		result, err = grain.HandleMessage(&message, false)
-// 	}
-// 	return result, err
-// }
-
-// func (p *RemoteGrainPool) Get(id CartId) (*FrameWithPayload, error) {
-// 	grain, err := p.findOrCreateGrain(id)
-// 	if err != nil {
-// 		return nil, err
-// 	}
-// 	return grain.GetCurrentState()
-// }

remote_grain_grpc.go

@@ -1,147 +0,0 @@
-package main
-
-import (
-	"bytes"
-	"context"
-	"fmt"
-	"log"
-	"time"
-
-	proto "git.tornberg.me/go-cart-actor/proto" // generated package name is 'messages'; aliased as proto for consistency
-	"google.golang.org/grpc"
-)
-
-// RemoteGrainGRPC is the gRPC-backed implementation of a remote grain.
-// It mirrors the previous RemoteGrain (TCP/frame based) while using the
-// new CartActor gRPC service. It implements the Grain interface so that
-// SyncedPool can remain largely unchanged when swapping transport layers.
-type RemoteGrainGRPC struct {
-	Id     CartId
-	Host   string
-	client proto.CartActorClient
-	// Optional: keep the underlying conn so higher-level code can close if needed
-	conn *grpc.ClientConn
-
-	// Per-call timeout settings (tunable)
-	mutateTimeout time.Duration
-	stateTimeout  time.Duration
-}
-
-// NewRemoteGrainGRPC constructs a remote grain adapter from an existing gRPC client.
-func NewRemoteGrainGRPC(id CartId, host string, client proto.CartActorClient) *RemoteGrainGRPC {
-	return &RemoteGrainGRPC{
-		Id:            id,
-		Host:          host,
-		client:        client,
-		mutateTimeout: 800 * time.Millisecond,
-		stateTimeout:  400 * time.Millisecond,
-	}
-}
-
-// NewRemoteGrainGRPCWithConn dials the target and creates the gRPC client.
-// target should be host:port (where the CartActor service is exposed).
-func NewRemoteGrainGRPCWithConn(id CartId, host string, target string, dialOpts ...grpc.DialOption) (*RemoteGrainGRPC, error) {
-	// NOTE: insecure for initial migration; should be replaced with TLS later.
-	baseOpts := []grpc.DialOption{grpc.WithInsecure(), grpc.WithBlock()}
-	baseOpts = append(baseOpts, dialOpts...)
-
-	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
-	defer cancel()
-
-	conn, err := grpc.DialContext(ctx, target, baseOpts...)
-	if err != nil {
-		return nil, err
-	}
-
-	client := proto.NewCartActorClient(conn)
-	return &RemoteGrainGRPC{
-		Id:            id,
-		Host:          host,
-		client:        client,
-		conn:          conn,
-		mutateTimeout: 800 * time.Millisecond,
-		stateTimeout:  400 * time.Millisecond,
-	}, nil
-}
-
-func (g *RemoteGrainGRPC) GetId() CartId {
-	return g.Id
-}
-
-// HandleMessage serializes the underlying mutation proto (without legacy message header)
-// and invokes the CartActor.Mutate RPC. It wraps the reply into a FrameWithPayload
-// for compatibility with existing higher-level code paths.
-func (g *RemoteGrainGRPC) HandleMessage(message *Message, isReplay bool) (*FrameWithPayload, error) {
-	if message == nil {
-		return nil, fmt.Errorf("nil message")
-	}
-	if isReplay {
-		// Remote replay not expected; ignore to keep parity with old implementation.
-		return nil, fmt.Errorf("replay not supported for remote grains")
-	}
-
-	handler, err := GetMessageHandler(message.Type)
-	if err != nil {
-		return nil, err
-	}
-
-	// Ensure timestamp set (legacy behavior)
-	if message.TimeStamp == nil {
-		ts := time.Now().Unix()
-		message.TimeStamp = &ts
-	}
-
-	// Marshal underlying proto payload only (no StorableMessageHeader)
-	var buf bytes.Buffer
-	err = handler.Write(message, &buf)
-	if err != nil {
-		return nil, fmt.Errorf("encode mutation payload: %w", err)
-	}
-
-	req := &proto.MutationRequest{
-		CartId:          g.Id.String(),
-		Type:            proto.MutationType(message.Type), // numeric mapping preserved
-		Payload:         buf.Bytes(),
-		ClientTimestamp: *message.TimeStamp,
-	}
-
-	ctx, cancel := context.WithTimeout(context.Background(), g.mutateTimeout)
-	defer cancel()
-
-	resp, err := g.client.Mutate(ctx, req)
-	if err != nil {
-		return nil, err
-	}
-
-	frame := MakeFrameWithPayload(RemoteHandleMutationReply, StatusCode(resp.StatusCode), resp.Payload)
-	return &frame, nil
-}
-
-// GetCurrentState calls CartActor.GetState and returns a FrameWithPayload
-// shaped like the legacy RemoteGetStateReply.
-func (g *RemoteGrainGRPC) GetCurrentState() (*FrameWithPayload, error) {
-	ctx, cancel := context.WithTimeout(context.Background(), g.stateTimeout)
-	defer cancel()
-
-	resp, err := g.client.GetState(ctx, &proto.StateRequest{
-		CartId: g.Id.String(),
-	})
-	if err != nil {
-		return nil, err
-	}
-	frame := MakeFrameWithPayload(RemoteGetStateReply, StatusCode(resp.StatusCode), resp.Payload)
-	return &frame, nil
-}
-
-// Close closes the underlying gRPC connection if this adapter created it.
-func (g *RemoteGrainGRPC) Close() error {
-	if g.conn != nil {
-		return g.conn.Close()
-	}
-	return nil
-}
-
-// Debug helper to log operations (optional).
-func (g *RemoteGrainGRPC) logf(format string, args ...interface{}) {
-	log.Printf("[remote-grain-grpc host=%s id=%s] %s", g.Host, g.Id.String(), fmt.Sprintf(format, args...))
-}

synced-pool.go

@@ -1,473 +0,0 @@
-package main
-
-import (
-	"context"
-	"fmt"
-	"log"
-	"sync"
-	"time"
-
-	proto "git.tornberg.me/go-cart-actor/proto"
-	"github.com/prometheus/client_golang/prometheus"
-	"github.com/prometheus/client_golang/prometheus/promauto"
-	"google.golang.org/grpc"
-	"k8s.io/apimachinery/pkg/watch"
-)
-
-// SyncedPool coordinates cart grain ownership across nodes using gRPC control plane
-// and cart actor services. Legacy frame / TCP code has been removed.
-//
-// Responsibilities:
-//   - Local grain access (delegates to GrainLocalPool)
-//   - Remote grain proxy management (RemoteGrainGRPC)
-//   - Cluster membership (AddRemote via discovery + negotiation)
-//   - Ownership acquisition (quorum via ConfirmOwner RPC)
-//   - Health/ping monitoring & remote removal
-//
-// Thread-safety: public methods that mutate internal maps lock p.mu (RWMutex).
-type SyncedPool struct {
-	Hostname string
-	local    *GrainLocalPool
-
-	mu sync.RWMutex
-
-	// Remote host state (gRPC only)
-	remoteHosts map[string]*RemoteHostGRPC // host -> remote host
-
-	// Remote grain proxies (by cart id)
-	remoteIndex map[CartId]Grain
-
-	// Discovery handler for re-adding hosts after failures
-	discardedHostHandler *DiscardedHostHandler
-
-	// Metrics / instrumentation dependencies already declared globally
-}
-
-// RemoteHostGRPC tracks a remote host's clients & health.
-type RemoteHostGRPC struct {
-	Host          string
-	Conn          *grpc.ClientConn
-	CartClient    proto.CartActorClient
-	ControlClient proto.ControlPlaneClient
-	MissedPings   int
-}
-
-func (r *RemoteHostGRPC) IsHealthy() bool {
-	return r.MissedPings < 3
-}
-
-var (
-	negotiationCount = promauto.NewCounter(prometheus.CounterOpts{
-		Name: "cart_remote_negotiation_total",
-		Help: "The total number of remote negotiations",
-	})
-	grainSyncCount = promauto.NewCounter(prometheus.CounterOpts{
-		Name: "cart_grain_sync_total",
-		Help: "The total number of grain owner changes",
-	})
-	connectedRemotes = promauto.NewGauge(prometheus.GaugeOpts{
-		Name: "cart_connected_remotes",
-		Help: "The number of connected remotes",
-	})
-	remoteLookupCount = promauto.NewCounter(prometheus.CounterOpts{
-		Name: "cart_remote_lookup_total",
-		Help: "The total number of remote lookups",
-	})
-)
-
-func NewSyncedPool(local *GrainLocalPool, hostname string, discovery Discovery) (*SyncedPool, error) {
-	p := &SyncedPool{
-		Hostname:             hostname,
-		local:                local,
-		remoteHosts:          make(map[string]*RemoteHostGRPC),
-		remoteIndex:          make(map[CartId]Grain),
-		discardedHostHandler: NewDiscardedHostHandler(1338),
-	}
-	p.discardedHostHandler.SetReconnectHandler(p.AddRemote)
-
-	if discovery != nil {
-		go func() {
-			time.Sleep(3 * time.Second) // allow gRPC server startup
-			log.Printf("Starting discovery watcher")
-			ch, err := discovery.Watch()
-			if err != nil {
-				log.Printf("Discovery error: %v", err)
-				return
-			}
-			for evt := range ch {
-				if evt.Host == "" {
-					continue
-				}
-				switch evt.Type {
-				case watch.Deleted:
-					if p.IsKnown(evt.Host) {
-						p.RemoveHost(evt.Host)
-					}
-				default:
-					if !p.IsKnown(evt.Host) {
-						log.Printf("Discovered host %s", evt.Host)
-						p.AddRemote(evt.Host)
-					}
-				}
-			}
-		}()
-	} else {
-		log.Printf("No discovery configured; expecting manual AddRemote or static host injection")
-	}
-
-	return p, nil
-}
-
-// ------------------------- Remote Host Management -----------------------------
-
-// AddRemote dials a remote host and initializes grain proxies.
-func (p *SyncedPool) AddRemote(host string) {
-	if host == "" || host == p.Hostname {
-		return
-	}
-
-	p.mu.Lock()
-	if _, exists := p.remoteHosts[host]; exists {
-		p.mu.Unlock()
-		return
-	}
-	p.mu.Unlock()
-
-	target := fmt.Sprintf("%s:1337", host)
-	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
-	defer cancel()
-	conn, err := grpc.DialContext(ctx, target, grpc.WithInsecure(), grpc.WithBlock())
-	if err != nil {
-		log.Printf("AddRemote: dial %s failed: %v", target, err)
-		return
-	}
-
-	cartClient := proto.NewCartActorClient(conn)
-	controlClient := proto.NewControlPlaneClient(conn)
-
-	// Health check (Ping) with limited retries
-	pings := 3
-	for pings > 0 {
-		ctxPing, cancelPing := context.WithTimeout(context.Background(), 1*time.Second)
-		_, pingErr := controlClient.Ping(ctxPing, &proto.Empty{})
-		cancelPing()
-		if pingErr == nil {
-			break
-		}
-		pings--
-		time.Sleep(200 * time.Millisecond)
-		if pings == 0 {
-			log.Printf("AddRemote: ping %s failed after retries: %v", host, pingErr)
-			conn.Close()
-			return
-		}
-	}
-
-	remote := &RemoteHostGRPC{
-		Host:          host,
-		Conn:          conn,
-		CartClient:    cartClient,
-		ControlClient: controlClient,
-		MissedPings:   0,
-	}
-
-	p.mu.Lock()
-	p.remoteHosts[host] = remote
-	p.mu.Unlock()
-	connectedRemotes.Set(float64(p.RemoteCount()))
-
-	log.Printf("Connected to remote host %s", host)
-
-	go p.pingLoop(remote)
-	go p.initializeRemote(remote)
-	go p.Negotiate()
-}
-
-// initializeRemote fetches remote cart ids and sets up remote grain proxies.
-func (p *SyncedPool) initializeRemote(remote *RemoteHostGRPC) {
-	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
-	defer cancel()
-	reply, err := remote.ControlClient.GetCartIds(ctx, &proto.Empty{})
-	if err != nil {
-		log.Printf("Init remote %s: GetCartIds error: %v", remote.Host, err)
-		return
-	}
-	count := 0
-	for _, idStr := range reply.CartIds {
-		if idStr == "" {
-			continue
-		}
-		p.SpawnRemoteGrain(ToCartId(idStr), remote.Host)
-		count++
-	}
-	log.Printf("Remote %s reported %d grains", remote.Host, count)
-}
-
-// RemoveHost removes remote host and its grains.
-func (p *SyncedPool) RemoveHost(host string) {
-	p.mu.Lock()
-	remote, exists := p.remoteHosts[host]
-	if exists {
-		delete(p.remoteHosts, host)
-	}
-	// remove grains pointing to host
-	for id, g := range p.remoteIndex {
-		if rg, ok := g.(*RemoteGrainGRPC); ok && rg.Host == host {
-			delete(p.remoteIndex, id)
-		}
-	}
-	p.mu.Unlock()
-
-	if exists {
-		remote.Conn.Close()
-	}
-	connectedRemotes.Set(float64(p.RemoteCount()))
-}
-
-// RemoteCount returns number of tracked remote hosts.
-func (p *SyncedPool) RemoteCount() int {
-	p.mu.RLock()
-	defer p.mu.RUnlock()
-	return len(p.remoteHosts)
-}
-
-func (p *SyncedPool) IsKnown(host string) bool {
-	if host == p.Hostname {
-		return true
-	}
-	p.mu.RLock()
-	defer p.mu.RUnlock()
-	_, ok := p.remoteHosts[host]
-	return ok
-}
-
-func (p *SyncedPool) ExcludeKnown(hosts []string) []string {
-	ret := make([]string, 0, len(hosts))
-	for _, h := range hosts {
-		if !p.IsKnown(h) {
-			ret = append(ret, h)
-		}
-	}
-	return ret
-}
-
-// ------------------------- Health / Ping -------------------------------------
-
-func (p *SyncedPool) pingLoop(remote *RemoteHostGRPC) {
-	ticker := time.NewTicker(3 * time.Second)
-	defer ticker.Stop()
-	for range ticker.C {
-		ctx, cancel := context.WithTimeout(context.Background(), 1*time.Second)
-		_, err := remote.ControlClient.Ping(ctx, &proto.Empty{})
-		cancel()
-		if err != nil {
-			remote.MissedPings++
-			log.Printf("Ping %s failed (%d)", remote.Host, remote.MissedPings)
-			if !remote.IsHealthy() {
-				log.Printf("Remote %s unhealthy, removing", remote.Host)
-				p.RemoveHost(remote.Host)
-				return
-			}
-			continue
-		}
-		remote.MissedPings = 0
-	}
-}
-
-func (p *SyncedPool) IsHealthy() bool {
-	p.mu.RLock()
-	defer p.mu.RUnlock()
-	for _, r := range p.remoteHosts {
-		if !r.IsHealthy() {
-			return false
-		}
-	}
-	return true
-}
-
-// ------------------------- Negotiation ---------------------------------------
-
-func (p *SyncedPool) Negotiate() {
-	negotiationCount.Inc()
-
-	p.mu.RLock()
-	hosts := make([]string, 0, len(p.remoteHosts)+1)
-	hosts = append(hosts, p.Hostname)
-	for h := range p.remoteHosts {
-		hosts = append(hosts, h)
-	}
-	remotes := make([]*RemoteHostGRPC, 0, len(p.remoteHosts))
-	for _, r := range p.remoteHosts {
-		remotes = append(remotes, r)
-	}
-	p.mu.RUnlock()
-
-	for _, r := range remotes {
-		ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
-		reply, err := r.ControlClient.Negotiate(ctx, &proto.NegotiateRequest{KnownHosts: hosts})
-		cancel()
-		if err != nil {
-			log.Printf("Negotiate with %s failed: %v", r.Host, err)
-			continue
-		}
-		for _, h := range reply.Hosts {
-			if !p.IsKnown(h) {
-				p.AddRemote(h)
-			}
-		}
-	}
-}
-
-// ------------------------- Grain Management ----------------------------------
-
-// RemoveRemoteGrain removes a remote grain mapping.
-func (p *SyncedPool) RemoveRemoteGrain(id CartId) {
-	p.mu.Lock()
-	delete(p.remoteIndex, id)
-	p.mu.Unlock()
-}
-
-// SpawnRemoteGrain creates/updates a remote grain proxy for a given host.
-func (p *SyncedPool) SpawnRemoteGrain(id CartId, host string) {
-	if id.String() == "" {
-		return
-	}
-	p.mu.Lock()
-	// If local grain exists, remove it (ownership changed)
-	if g, ok := p.local.grains[id]; ok && g != nil {
-		delete(p.local.grains, id)
-	}
-	remoteHost, ok := p.remoteHosts[host]
-	if !ok {
-		p.mu.Unlock()
-		log.Printf("SpawnRemoteGrain: host %s unknown (id=%s), attempting AddRemote", host, id)
-		go p.AddRemote(host)
-		return
-	}
-	rg := NewRemoteGrainGRPC(id, host, remoteHost.CartClient)
-	p.remoteIndex[id] = rg
-	p.mu.Unlock()
-}
-
-// GetHealthyRemotes returns a copy slice of healthy remote hosts.
-func (p *SyncedPool) GetHealthyRemotes() []*RemoteHostGRPC {
-	p.mu.RLock()
-	defer p.mu.RUnlock()
-	ret := make([]*RemoteHostGRPC, 0, len(p.remoteHosts))
-	for _, r := range p.remoteHosts {
-		if r.IsHealthy() {
-			ret = append(ret, r)
-		}
-	}
-	return ret
-}
-
-// RequestOwnership attempts to become owner of a cart, requiring quorum.
-// On success local grain is (or will be) created; peers spawn remote proxies.
-func (p *SyncedPool) RequestOwnership(id CartId) error {
-	ok := 0
-	all := 0
-	remotes := p.GetHealthyRemotes()
-	for _, r := range remotes {
-		ctx, cancel := context.WithTimeout(context.Background(), 800*time.Millisecond)
-		reply, err := r.ControlClient.ConfirmOwner(ctx, &proto.OwnerChangeRequest{
-			CartId:  id.String(),
-			NewHost: p.Hostname,
-		})
-		cancel()
-		all++
-		if err != nil || reply == nil || !reply.Accepted {
-			log.Printf("ConfirmOwner failure from %s for %s: %v (reply=%v)", r.Host, id, err, reply)
-			continue
-		}
-		ok++
-	}
-
-	// Quorum rule mirrors legacy:
-	//  - If fewer than 3 total, require all.
-	//  - Else require majority (ok >= all/2).
-	if (all < 3 && ok < all) || ok < (all/2) {
-		p.removeLocalGrain(id)
-		return fmt.Errorf("quorum not reached (ok=%d all=%d)", ok, all)
-	}
-	grainSyncCount.Inc()
-	return nil
-}
-
-func (p *SyncedPool) removeLocalGrain(id CartId) {
-	p.mu.Lock()
-	delete(p.local.grains, id)
-	p.mu.Unlock()
-}
-
-// getGrain returns a local or remote grain; if absent, attempts ownership.
-func (p *SyncedPool) getGrain(id CartId) (Grain, error) {
-	p.mu.RLock()
-	localGrain, isLocal := p.local.grains[id]
-	remoteGrain, isRemote := p.remoteIndex[id]
-	p.mu.RUnlock()
-
-	if isLocal && localGrain != nil {
-		return localGrain, nil
-	}
-	if isRemote {
-		remoteLookupCount.Inc()
-		return remoteGrain, nil
-	}
-
-	// Attempt to claim ownership (async semantics preserved)
-	go p.RequestOwnership(id)
-
-	// Create local grain (lazy spawn) - may be rolled back by quorum failure
-	grain, err := p.local.GetGrain(id)
-	if err != nil {
-		return nil, err
-	}
-	return grain, nil
-}
-
-// Process applies mutation(s) to a grain (local or remote).
-func (p *SyncedPool) Process(id CartId, messages ...Message) (*FrameWithPayload, error) {
-	grain, err := p.getGrain(id)
-	if err != nil {
-		return nil, err
-	}
-	var res *FrameWithPayload
-	for _, m := range messages {
-		res, err = grain.HandleMessage(&m, false)
-		if err != nil {
-			return nil, err
-		}
-	}
-	return res, nil
-}
-
-// Get returns current state of a grain (local or remote).
-func (p *SyncedPool) Get(id CartId) (*FrameWithPayload, error) {
-	grain, err := p.getGrain(id)
-	if err != nil {
-		return nil, err
-	}
-	return grain.GetCurrentState()
-}
-
-// Close notifies remotes this host is terminating.
-func (p *SyncedPool) Close() {
-	p.mu.RLock()
-	remotes := make([]*RemoteHostGRPC, 0, len(p.remoteHosts))
-	for _, r := range p.remoteHosts {
-		remotes = append(remotes, r)
-	}
-	p.mu.RUnlock()
-
-	for _, r := range remotes {
-		go func(rh *RemoteHostGRPC) {
-			ctx, cancel := context.WithTimeout(context.Background(), 1*time.Second)
-			_, err := rh.ControlClient.Closing(ctx, &proto.ClosingNotice{Host: p.Hostname})
-			cancel()
-			if err != nil {
-				log.Printf("Close notify to %s failed: %v", rh.Host, err)
-			}
-		}(r)
-	}
-}

tcp-connection_test.go

@@ -1,8 +0,0 @@
-/*
-Legacy TCP networking (GenericListener / Frame protocol) has been removed
-as part of the gRPC migration. This file intentionally contains no tests.
-
-Keeping an empty Go file (with a package declaration) ensures the old
-tcp-connection test target no longer runs without causing build issues.
-*/
-package main