fix

agents.md

@@ -0,0 +1,67 @@
+# go-redis-inventory — agents map
+
+Redis-backed **inventory + reservation** service. Tracks stock levels and
+runs atomic reservation operations via Lua scripts; also consumes an
+`inventory_changed` pub/sub channel to mirror upstream changes.
+
+## Where to start
+
+- `README.md` — start here, it has the high-level intent.
+- `pkg/inventory/types.go` — all the data structures (`InventoryItem`,
+  `InventoryReference`, `CartReserveRequest`, …).
+- `pkg/inventory/redis_service.go` — basic get / batch get / reserve path
+  + the Lua scripts (`reserveScript`, `reservationCheck`).
+- `pkg/inventory/redis_reservation_service.go` — cart-shaped reservations
+  with release/availability semantics + corresponding `_test.go`.
+- `pkg/inventory/listener.go` — `InventoryChangeListener` on the
+  `inventory_changed` pub/sub channel.
+- `pkg/inventory/adapter.go` — `ReservationPolicyAdapter` bridging to
+  `platform/inventory.ReservationPolicy`.
+
+## Architecture
+
+- **Two responsibilities, one process**: (1) hold and serve inventory state;
+  (2) mirror upstream changes via pub/sub.
+- **Atomicity**: reservation idempotency and TTL semantics come from Lua
+  scripts embedded here. The scripts are the seam — if they change, the
+  test in `redis_reservation_service_test.go` is the contract.
+- **Adapter**: the `ReservationPolicyAdapter` is the seam to
+  `platform/inventory`. Two adapters (this service and any other downstream
+  caller) is what makes it a real seam, not a hypothetical one.
+
+## Important files by area
+
+| Area                          | File                                                |
+| ----------------------------- | --------------------------------------------------- |
+| Domain model                  | `pkg/inventory/types.go`                            |
+| Core service                  | `pkg/inventory/redis_service.go`                    |
+| Reservation service (cart)    | `pkg/inventory/redis_reservation_service.go`        |
+| Pub/sub listener              | `pkg/inventory/listener.go`                         |
+| Platform adapter              | `pkg/inventory/adapter.go`                          |
+| Reservation tests             | `pkg/inventory/redis_reservation_service_test.go`   |
+
+## Cross-project seams
+
+- **`platform/inventory`**: implements `ReservationPolicy` via the adapter.
+- **`go-cart-actor`**: consumes reservations through that adapter.
+- **Redis pub/sub**: receives `inventory_changed` events.
+
+## Improvement suggestions
+
+- **`types.go` carries mixed concerns** — `InventoryItem` (storage) sits
+  next to `CartReserveRequest` (request). Split into `types/`
+  (storage-level) and `types/cart.go` (request) so callers can depend on
+  only the slice they need.
+- **Two reservation services**: `redis_service.go` has its own reserve,
+  `redis_reservation_service.go` has another, plus a `Level` type
+  (`level.go`). The relationship between them isn't documented; an
+  architecture paragraph at the top of the package would help
+  (`doc.go` or `pkg/inventory/README.md`).
+- **`listener.go` is single-channel** — it consumes only `inventory_changed`.
+  If more channels need the same lifecycle (reconnect, dedupe, back-off),
+  factor out a tiny `pubsub.Consumer` and let the listener wrap it.
+- **Lua scripts live inside Go source.** Promote them to `.lua` files,
+  registered via `//go:embed` — that makes them version-controlled and
+  testable independently of the Go code.
+- **No config validation.** A malformed `REDIS_URL`/`CHANNEL` boots and
+  fails at first call. Fail fast in `main.go` with explicit error messages.

go.mod

@@ -4,11 +4,16 @@ go 1.26.2
 
 require (
 	github.com/alicebob/miniredis/v2 v2.35.0
-	github.com/redis/go-redis/v9 v9.16.0
+	github.com/redis/go-redis/v9 v9.20.0
 )
 
 require (
+	git.k6n.net/mats/platform v0.0.0
 	github.com/cespare/xxhash/v2 v2.3.0 // indirect
-	github.com/dgryski/go-rendezvous v0.0.0-20200823014737-9f7001d12a5f // indirect
+	github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc // indirect
+	github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 // indirect
+	github.com/stretchr/testify v1.11.1 // indirect
 	github.com/yuin/gopher-lua v1.1.1 // indirect
+	go.uber.org/atomic v1.11.0 // indirect
+	golang.org/x/sys v0.46.0 // indirect
 )

go.sum

@@ -6,9 +6,14 @@ github.com/bsm/gomega v1.27.10 h1:yeMWxP2pV2fG3FgAODIY8EiRE3dy0aeFYt4l7wh6yKA=
 github.com/bsm/gomega v1.27.10/go.mod h1:JyEr/xRbxbtgWNi8tIEVPUYZ5Dzef52k01W3YH0H+O0=
 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/dgryski/go-rendezvous v0.0.0-20200823014737-9f7001d12a5f h1:lO4WD4F/rVNCu3HqELle0jiPLLBs70cWOduZpkS1E78=
+github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc h1:U9qPSI2PIWSS1VwoXQT9A3Wy9MM3WgvqSxFWenqJduM=
-github.com/dgryski/go-rendezvous v0.0.0-20200823014737-9f7001d12a5f/go.mod h1:cuUVRXasLTGF7a8hSLbxyZXjz+1KgoB3wDUb6vlszIc=
+github.com/klauspost/cpuid/v2 v2.2.10 h1:tBs3QSyvjDyFTq3uoc/9xFpCuOsJQFNPiAhYdw2skhE=
-github.com/redis/go-redis/v9 v9.16.0 h1:OotgqgLSRCmzfqChbQyG1PHC3tLNR89DG4jdOERSEP4=
+github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 h1:Jamvg5psRIccs7FGNTlIRMkT8wgtp5eCXdBlqhYGL6U=
-github.com/redis/go-redis/v9 v9.16.0/go.mod h1:u410H11HMLoB+TP67dz8rL9s6QW2j76l0//kSOd3370=
+github.com/redis/go-redis/v9 v9.20.0 h1:WnQYxLkgO2xiXTCJY0ldIiI8dNqCDlQAG+AtaH7a2a0=
+github.com/stretchr/testify v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu7U=
 github.com/yuin/gopher-lua v1.1.1 h1:kYKnWBjvbNP4XLT3+bPEwAXJx262OhaHDWDVOPjL46M=
 github.com/yuin/gopher-lua v1.1.1/go.mod h1:GBR0iDaNXjAgGg9zfCvksxSRnQx76gclCIb7kdAd1Pw=
+github.com/zeebo/xxh3 v1.1.0 h1:s7DLGDK45Dyfg7++yxI0khrfwq9661w9EN78eP/UZVs=
+go.uber.org/atomic v1.11.0 h1:ZvwS0R+56ePWxUNi+Atn9dWONBPp/AUETXlHW0DxSjE=
+golang.org/x/sys v0.46.0 h1:noSf2Fq6F8DBgS+LysIkx7rIExoNHJsxOAtPp4rthXw=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=

pkg/inventory/adapter.go

@@ -0,0 +1,42 @@
+package inventory
+
+import (
+	"context"
+
+	platforminv "git.k6n.net/mats/platform/inventory"
+)
+
+// ReservationPolicyAdapter wraps a RedisCartReservationService to satisfy the
+// platform/inventory.ReservationPolicy interface. It translates between the
+// platform's value types (SKU, LocationID, CartID) and the Redis-level types
+// used internally by go-redis-inventory.
+type ReservationPolicyAdapter struct {
+	inner *RedisCartReservationService
+}
+
+// NewReservationPolicyAdapter creates an adapter that satisfies
+// platform/inventory.ReservationPolicy by delegating to the Redis-backed
+// reservation service.
+func NewReservationPolicyAdapter(inner *RedisCartReservationService) *ReservationPolicyAdapter {
+	return &ReservationPolicyAdapter{inner: inner}
+}
+
+func (a *ReservationPolicyAdapter) Reserve(ctx context.Context, req platforminv.CartReserveRequest) error {
+	return a.inner.ReserveForCart(ctx, CartReserveRequest{
+		InventoryReference: &InventoryReference{
+			SKU:        SKU(req.SKU),
+			LocationID: LocationID(req.LocationID),
+		},
+		CartID:   CartID(req.CartID),
+		Quantity: req.Quantity,
+		TTL:      req.TTL,
+	})
+}
+
+func (a *ReservationPolicyAdapter) Release(ctx context.Context, sku platforminv.SKU, locationID platforminv.LocationID, cartID platforminv.CartID) error {
+	return a.inner.ReleaseForCart(ctx, SKU(sku), LocationID(locationID), CartID(cartID))
+}
+
+func (a *ReservationPolicyAdapter) Available(ctx context.Context, sku platforminv.SKU, locationID platforminv.LocationID) (int64, error) {
+	return a.inner.GetAvailableInventory(ctx, SKU(sku), LocationID(locationID))
+}

pkg/inventory/doc.go

@@ -0,0 +1,26 @@
+// Package inventory is the Redis-backed stock + reservation service.
+//
+// Two distinct services coexist in this package and they are NOT
+// redundant; they exist for different callers:
+//
+//   - redis_service.go            — stock levels and basic get/batch/reserve.
+//   - redis_reservation_service.go — cart-shaped reservations (with release
+//                                     + available-quantity semantics, used by
+//                                     go-cart-actor via the adapter).
+//
+// `Level` (level.go) is the canonical shape returned by readers and
+// accepted by writers; it is reused across both services.
+//
+// adapter.go bridges to platform/inventory.ReservationPolicy so other
+// services depend on the platform interface, not on this package.
+//
+// listener.go subscribes to the inventory_changed Redis pub/sub channel
+// and mirrors upstream events into the local cache.
+//
+// Request and reservation DTOs (CartReserveRequest, ReserveRequest,
+// CartID, ReservationStatus, ReservationSummary) now live in
+// request_types.go. Storage types (InventoryItem, InventoryReference,
+// InventoryResult) remain in types.go. When adding a new request shape,
+// put it in request_types.go; when adding a new storage shape, put it
+// in types.go.
+package inventory

pkg/inventory/request_types.go

@@ -0,0 +1,37 @@
+package inventory
+
+import "time"
+
+// Request and reservation DTOs — separated from storage types (types.go)
+// so callers that only need read-side shapes don't pull in cart-reservation
+// concepts. See doc.go for the split rationale.
+
+type CartID string
+
+type ReserveRequest struct {
+	*InventoryReference
+	Quantity uint32
+}
+
+type CartReserveRequest struct {
+	*InventoryReference
+	CartID   CartID
+	Quantity uint32
+	TTL      time.Duration
+}
+
+// CartReservationService interface was removed in favor of
+// platform/inventory.ReservationPolicy. Consumers should depend on the
+// platform seam; the concrete *RedisCartReservationService implements its
+// methods directly.
+
+type ReservationStatus struct {
+	Active        bool
+	RemainingTime time.Duration
+}
+
+type ReservationSummary struct {
+	ReservationCount int64     `json:"reservation_count"`
+	EarliestRelease  time.Time `json:"earliest_release"`
+	RemainingItems   int64     `json:"remaining_items"`
+}

pkg/inventory/types.go

@@ -33,41 +33,7 @@ type InventoryService interface {
 	ReservationCheck(ctx context.Context, req ...ReserveRequest) (*ReserveRequest, error)
 }
 
-type ReserveRequest struct {
-	*InventoryReference
-	Quantity uint32
-}
-
 type InventoryResult struct {
 	*InventoryReference
 	Quantity uint32
 }
-
-type CartID string
-
-type CartReserveRequest struct {
-	*InventoryReference
-	CartID   CartID
-	Quantity uint32
-	TTL      time.Duration
-}
-
-type CartReservationService interface {
-	ReserveForCart(ctx context.Context, req CartReserveRequest) error
-	ReleaseForCart(ctx context.Context, sku SKU, locationID LocationID, cartID CartID) error
-	GetAvailableInventory(ctx context.Context, sku SKU, locationID LocationID) (int64, error)
-	GetReservationExpiry(ctx context.Context, sku SKU, locationID LocationID, cartID CartID) (time.Time, error)
-	GetReservationStatus(ctx context.Context, sku SKU, locationID LocationID, cartID CartID) (*ReservationStatus, error)
-	GetReservationSummary(ctx context.Context, sku SKU, locationID LocationID) (*ReservationSummary, error)
-}
-
-type ReservationStatus struct {
-	Active        bool
-	RemainingTime time.Duration
-}
-
-type ReservationSummary struct {
-	ReservationCount int64     `json:"reservation_count"`
-	EarliestRelease  time.Time `json:"earliest_release"`
-	RemainingItems   int64     `json:"remaining_items"`
-}