refactor

cmd/backoffice/main.go

@@ -20,8 +20,6 @@ func main() {
 	app, err := backofficeadmin.New(backofficeadmin.Config{
 		DataDir:         config.EnvString("CART_DIR", "data"),
 		CheckoutDataDir: config.EnvString("CHECKOUT_DIR", "checkout-data"),
-		RedisAddress:    os.Getenv("REDIS_ADDRESS"),
-		RedisPassword:   os.Getenv("REDIS_PASSWORD"),
 	})
 	if err != nil {
 		log.Fatalf("Error creating backoffice: %v", err)

cmd/cart/main.go

@@ -104,21 +104,6 @@ type CartChangeEvent struct {
 	Mutations []actor.ApplyResult `json:"mutations"`
 }
 
-func matchesSkuAndLocation(update inventory.InventoryResult, item cart.CartItem) bool {
-	if string(update.SKU) == item.Sku {
-		if update.LocationID == "se" && item.StoreId == nil {
-			return true
-		}
-		if item.StoreId == nil {
-			return false
-		}
-		if *item.StoreId == string(update.LocationID) {
-			return true
-		}
-	}
-	return false
-}
-
 // catalogProjectionCache is the cart's per-pod, cold-start-ready catalog
 // projection cache, backed by platform/catalog.ProjectionStore. It consumes the
 // catalog.projection_published wire — a full snapshot (begin/chunk/end, framed by
@@ -232,18 +217,13 @@ func main() {
 		Password: redisPassword,
 		DB:       0,
 	})
-	inventoryService, err := inventory.NewRedisInventoryService(rdb)
-	if err != nil {
-		log.Fatalf("Error creating inventory service: %v\n", err)
-	}
-	_ = inventoryService
-
 	inventoryReservationService, err := inventory.NewRedisCartReservationService(rdb)
 	if err != nil {
 		log.Fatalf("Error creating inventory reservation service: %v\n", err)
 	}
+	reservationPolicy := inventory.NewReservationPolicyAdapter(inventoryReservationService)
 
-	reg := cart.NewCartMultationRegistry(cart.NewCartMutationContext(inventoryReservationService))
+	reg := cart.NewCartMultationRegistry(cart.NewCartMutationContext(reservationPolicy))
 	reg.RegisterProcessor(
 		actor.NewMutationProcessor(func(ctx context.Context, g *cart.CartGrain) error {
 			_, span := tracer.Start(ctx, "Totals and promotions")

cmd/checkout/klarna-handlers.go

@@ -11,7 +11,7 @@ import (
 	"git.k6n.net/mats/go-cart-actor/pkg/cart"
 	"git.k6n.net/mats/go-cart-actor/pkg/checkout"
 	messages "git.k6n.net/mats/go-cart-actor/proto/checkout"
-	"git.k6n.net/mats/go-redis-inventory/pkg/inventory"
+	"git.k6n.net/mats/platform/inventory"
 	"google.golang.org/protobuf/types/known/timestamppb"
 )
 
@@ -244,7 +244,7 @@ func createOrderFromCheckout(ctx context.Context, s *CheckoutPoolServer, grain *
 
 func getLocationId(item *cart.CartItem) inventory.LocationID {
 	if item.StoreId == nil || *item.StoreId == "" {
-		return "se"
+		return inventory.LocationID("se")
 	}
 	return inventory.LocationID(*item.StoreId)
 }
@@ -259,23 +259,6 @@ func shouldTrackInventory(item *cart.CartItem) bool {
 	return false
 }
 
-func getInventoryRequests(items []*cart.CartItem) []inventory.ReserveRequest {
-	var requests []inventory.ReserveRequest
-	for _, item := range items {
-		if item == nil || !shouldTrackInventory(item) {
-			continue
-		}
-		requests = append(requests, inventory.ReserveRequest{
-			InventoryReference: &inventory.InventoryReference{
-				SKU:        inventory.SKU(item.Sku),
-				LocationID: getLocationId(item),
-			},
-			Quantity: uint32(item.Quantity),
-		})
-	}
-	return requests
-}
-
 func (a *CheckoutPoolServer) getGrainFromKlarnaOrder(ctx context.Context, order *CheckoutOrder) (*checkout.CheckoutGrain, error) {
 	cartId, ok := cart.ParseCartId(order.MerchantReference1)
 	if !ok {

cmd/checkout/main.go

@@ -15,7 +15,7 @@ import (
 	"git.k6n.net/mats/go-cart-actor/pkg/checkout"
 	"git.k6n.net/mats/go-cart-actor/pkg/proxy"
 	"git.k6n.net/mats/go-cart-actor/pkg/telemetry"
-	"git.k6n.net/mats/go-redis-inventory/pkg/inventory"
+	redisinv "git.k6n.net/mats/go-redis-inventory/pkg/inventory"
 	"git.k6n.net/mats/platform/config"
 	"git.k6n.net/mats/platform/rabbit"
 	"git.k6n.net/mats/platform/tax"
@@ -102,15 +102,12 @@ func main() {
 		Password: redisPassword,
 		DB:       0,
 	})
-	inventoryService, err := inventory.NewRedisInventoryService(rdb)
-	if err != nil {
-		log.Fatalf("Error creating inventory service: %v\n", err)
-	}
 
-	reservationService, err := inventory.NewRedisCartReservationService(rdb)
+	reservationService, err := redisinv.NewRedisCartReservationService(rdb)
 	if err != nil {
 		log.Fatalf("Error creating reservation service: %v\n", err)
 	}
+	reservationPolicy := redisinv.NewReservationPolicyAdapter(reservationService)
 
 	checkoutDir := os.Getenv("CHECKOUT_DIR")
 	if checkoutDir == "" {
@@ -194,8 +191,7 @@ func main() {
 	pool.AddListener(checkoutFeed)
 
 	syncedServer = NewCheckoutPoolServer(pool, fmt.Sprintf("%s, %s", name, podIp), klarnaClient, cartClient, adyenClient, orderClient, orderHandler)
-	syncedServer.inventoryService = inventoryService
-	syncedServer.reservationService = reservationService
+	syncedServer.reservationPolicy = reservationPolicy
 	syncedServer.taxProvider = selectTaxProvider()
 
 	mux := http.NewServeMux()

cmd/checkout/order_client.go

@@ -66,6 +66,7 @@ type OrderLine struct {
 	Quantity  int32  `json:"quantity"`
 	UnitPrice int64  `json:"unitPrice"`
 	TaxRate   int32  `json:"taxRate"`
+	DropShip  bool   `json:"drop_ship,omitempty"`
 	Location  string `json:"location,omitempty"`
 }
 

cmd/checkout/order_create.go

@@ -58,6 +58,7 @@ func buildOrderLinesFromGrain(grain *checkout.CheckoutGrain) []OrderLine {
 			// CartItem.Tax and OrderLine.TaxRate share the platform basis-point scale
 			// (2500 = 25%), so the rate passes through unchanged.
 			TaxRate:   int32(it.Tax),
+			DropShip:  it.DropShip,
 			Location:  location,
 		})
 	}

cmd/checkout/pool-server.go

@@ -16,8 +16,8 @@ import (
 	"git.k6n.net/mats/platform/tax"
 	messages "git.k6n.net/mats/go-cart-actor/proto/checkout"
 
+	"git.k6n.net/mats/platform/inventory"
 	adyen "github.com/adyen/adyen-go-api-library/v21/src/adyen"
-	"git.k6n.net/mats/go-redis-inventory/pkg/inventory"
 
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promauto"
@@ -52,8 +52,7 @@ type CheckoutPoolServer struct {
 	cartClient       *CartClient
 	orderClient      *OrderClient
 	orderHandler     *AmqpOrderHandler
-	inventoryService   *inventory.RedisInventoryService
-	reservationService *inventory.RedisCartReservationService
+	reservationPolicy inventory.ReservationPolicy
 	taxProvider       tax.Provider
 }
 
@@ -556,14 +555,14 @@ func (s *CheckoutPoolServer) Serve(mux *http.ServeMux) {
 }
 
 func (s *CheckoutPoolServer) releaseCartReservations(ctx context.Context, grain *checkout.CheckoutGrain) {
-	if s.reservationService == nil || grain.CartState == nil {
+	if s.reservationPolicy == nil || grain.CartState == nil {
 		return
 	}
 	for _, item := range grain.CartState.Items {
 		if item == nil || !shouldTrackInventory(item) {
 			continue
 		}
-		if err := s.reservationService.ReleaseForCart(ctx, inventory.SKU(item.Sku), getLocationId(item), inventory.CartID(grain.CartId.String())); err != nil {
+		if err := s.reservationPolicy.Release(ctx, inventory.SKU(item.Sku), getLocationId(item), inventory.CartID(grain.CartId.String())); err != nil {
 			logger.WarnContext(ctx, "failed to release cart reservation", "sku", item.Sku, "err", err)
 		}
 	}

cmd/checkout/utils.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"context"
+	"fmt"
 	"log"
 	"net/http"
 	"strings"
@@ -9,6 +10,7 @@ import (
 
 	"git.k6n.net/mats/go-cart-actor/pkg/cart"
 	"git.k6n.net/mats/go-cart-actor/pkg/checkout"
+	"git.k6n.net/mats/platform/inventory"
 	"go.opentelemetry.io/otel/attribute"
 	"go.opentelemetry.io/otel/metric"
 )
@@ -77,12 +79,23 @@ func getCountryFromHost(host string) string {
 }
 
 func (a *CheckoutPoolServer) reserveInventory(ctx context.Context, grain *checkout.CheckoutGrain) error {
-	if a.inventoryService != nil {
-		inventoryRequests := getInventoryRequests(grain.CartState.Items)
-		_, err := a.inventoryService.ReservationCheck(ctx, inventoryRequests...)
+	if a.reservationPolicy == nil {
+		return nil
+	}
+	for _, item := range grain.CartState.Items {
+		if item == nil || !shouldTrackInventory(item) {
+			continue
+		}
+		loc := inventory.LocationID("se")
+		if item.StoreId != nil && *item.StoreId != "" {
+			loc = inventory.LocationID(*item.StoreId)
+		}
+		avail, err := a.reservationPolicy.Available(ctx, inventory.SKU(item.Sku), loc)
 		if err != nil {
-			logger.WarnContext(ctx, "placeorder inventory check failed")
-			return err
+			return fmt.Errorf("inventory check failed for SKU %s: %w", item.Sku, err)
+		}
+		if int64(item.Quantity) > avail {
+			return fmt.Errorf("insufficient inventory for SKU %s: have %d, need %d", item.Sku, avail, item.Quantity)
 		}
 	}
 	return nil

cmd/inventory/batch.go

@@ -0,0 +1,100 @@
+package main
+
+import (
+	"encoding/json"
+	"io"
+	"net/http"
+
+	"git.k6n.net/mats/go-redis-inventory/pkg/inventory"
+)
+
+// batchItem is one stock set in a batch request. LocationID is optional; an
+// empty value defaults to the service's country location (the same location the
+// catalog-feed listener writes to).
+type batchItem struct {
+	SKU        string `json:"sku"`
+	LocationID string `json:"locationId,omitempty"`
+	Quantity   int64  `json:"quantity"`
+}
+
+// batchResult mirrors one input item with the location actually written and an
+// optional per-item error (empty on success).
+type batchResult struct {
+	SKU        string `json:"sku"`
+	LocationID string `json:"locationId"`
+	Quantity   int64  `json:"quantity"`
+	Error      string `json:"error,omitempty"`
+}
+
+// batchInventoryHandler SETS stock to absolute values for many SKUs in one
+// pipelined call — for re-seeding/import and for testing the inventory + reserve
+// paths directly. Same write as the catalog-feed listener (UpdateInventory +
+// level crossing), so a value set here is authoritative until the next
+// catalog.item_changed for that SKU overwrites it (catalog is the source of
+// truth). Body is a JSON array of {sku, locationId?, quantity}.
+func (srv *Server) batchInventoryHandler(w http.ResponseWriter, r *http.Request) {
+	body, err := io.ReadAll(io.LimitReader(r.Body, 16<<20)) // 16 MiB
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusBadRequest)
+		return
+	}
+	var items []batchItem
+	if err := json.Unmarshal(body, &items); err != nil {
+		http.Error(w, "body must be a JSON array of {sku, locationId?, quantity}: "+err.Error(), http.StatusBadRequest)
+		return
+	}
+	if len(items) == 0 {
+		http.Error(w, "empty batch", http.StatusBadRequest)
+		return
+	}
+
+	ctx := r.Context()
+	results := make([]batchResult, len(items))
+	pipe := srv.rdb.Pipeline()
+	for i, it := range items {
+		loc := it.LocationID
+		if loc == "" {
+			loc = country
+		}
+		results[i] = batchResult{SKU: it.SKU, LocationID: loc, Quantity: it.Quantity}
+		if it.SKU == "" {
+			results[i].Error = "sku is required"
+			continue
+		}
+		srv.inventoryService.UpdateInventory(ctx, pipe, inventory.SKU(it.SKU), inventory.LocationID(loc), it.Quantity)
+	}
+
+	hadError := false
+	if _, err := pipe.Exec(ctx); err != nil {
+		// Exec reports the first failing command; flag the whole batch rather than
+		// guess which items committed.
+		hadError = true
+		for i := range results {
+			if results[i].Error == "" {
+				results[i].Error = err.Error()
+			}
+		}
+	} else {
+		// Emit level crossings for the items that were actually written, so the
+		// finder/level listeners react the same way they do for catalog feeds.
+		for i := range results {
+			if results[i].Error == "" {
+				emitLevelIfChanged(ctx, srv.rdb, srv.conn, country, lowWatermark, results[i].SKU, results[i].LocationID, results[i].Quantity)
+			}
+		}
+	}
+	for i := range results {
+		if results[i].Error != "" {
+			hadError = true
+			break
+		}
+	}
+
+	status := http.StatusOK
+	if hadError {
+		status = http.StatusMultiStatus // 207
+	}
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(status)
+	json.NewEncoder(w).Encode(map[string]any{"count": len(results), "results": results})
+}

cmd/inventory/commit.go

@@ -40,6 +40,11 @@ func commitOrder(ctx context.Context, rdb *redis.Client, svc *inventory.RedisInv
 		if line.SKU == "" || line.Quantity <= 0 {
 			continue
 		}
+		// Drop-ship items are fulfilled by the supplier — never decrement
+		// local stock for them.
+		if line.DropShip {
+			continue
+		}
 		loc := inventory.LocationID(defaultLoc)
 		if line.Location != "" {
 			loc = inventory.LocationID(line.Location)

cmd/inventory/main.go

@@ -24,6 +24,11 @@ import (
 type Server struct {
 	inventoryService   *inventory.RedisInventoryService
 	reservationService *inventory.RedisCartReservationService
+
+	// rdb + conn back the batch write path (pipelined UpdateInventory + level
+	// crossing). conn is nil when RABBIT_HOST is unset; emit is then skipped.
+	rdb  *redis.Client
+	conn *rabbit.Conn
 }
 
 func (srv *Server) livezHandler(w http.ResponseWriter, r *http.Request) {
@@ -124,13 +129,16 @@ func main() {
 		return
 	}
 
-	server := &Server{inventoryService: s, reservationService: r}
+	server := &Server{inventoryService: s, reservationService: r, rdb: rdb}
 
 	// Set up HTTP routes
 	http.HandleFunc("/livez", server.livezHandler)
 	http.HandleFunc("/readyz", server.readyzHandler)
 	http.HandleFunc("/inventory/{sku}/{locationId}", server.getInventoryHandler)
 	http.HandleFunc("/reservations/{sku}/{locationId}", server.getReservationHandler)
+	http.HandleFunc("POST /reservations", server.reserveInventoryHandler)
+	http.HandleFunc("POST /reservations/release", server.releaseReservationHandler)
+	http.HandleFunc("POST /inventory/batch", server.batchInventoryHandler)
 
 	stockhandler := &StockHandler{
 		MainStockLocationID: inventory.LocationID(country),
@@ -151,6 +159,9 @@ func main() {
 		// The catalog-feed handler emits inventory.level_changed crossings
 		// directly on this connection as it writes stock.
 		stockhandler.conn = conn
+		// Share the bus connection with the batch handler so its writes emit
+		// inventory.level_changed crossings too.
+		server.conn = conn
 		// Reconnecting consumer: re-listen on reconnect.
 		conn.NotifyOnReconnect(func() {
 			ch, err := conn.Channel()

cmd/inventory/reservations.go

@@ -0,0 +1,98 @@
+package main
+
+import (
+	"encoding/json"
+	"errors"
+	"net/http"
+	"time"
+
+	"git.k6n.net/mats/go-redis-inventory/pkg/inventory"
+)
+
+type reservationLineReq struct {
+	SKU        string `json:"sku"`
+	LocationID string `json:"locationId"`
+	Quantity   uint32 `json:"quantity"`
+}
+
+type reservationBatchReq struct {
+	HolderID   string               `json:"holderId"`
+	TTLSeconds int64                `json:"ttlSeconds,omitempty"`
+	Lines      []reservationLineReq `json:"lines"`
+}
+
+func (srv *Server) reserveInventoryHandler(w http.ResponseWriter, r *http.Request) {
+	var req reservationBatchReq
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+		http.Error(w, "invalid request body", http.StatusBadRequest)
+		return
+	}
+	if req.HolderID == "" {
+		http.Error(w, "missing holderId", http.StatusBadRequest)
+		return
+	}
+	if len(req.Lines) == 0 {
+		http.Error(w, "missing lines", http.StatusBadRequest)
+		return
+	}
+	ttl := 15 * time.Minute
+	if req.TTLSeconds > 0 {
+		ttl = time.Duration(req.TTLSeconds) * time.Second
+	}
+	for _, line := range req.Lines {
+		if line.SKU == "" || line.LocationID == "" || line.Quantity == 0 {
+			http.Error(w, "each line must include sku, locationId, and quantity", http.StatusBadRequest)
+			return
+		}
+		if err := srv.reservationService.ReserveForCart(r.Context(), inventory.CartReserveRequest{
+			InventoryReference: &inventory.InventoryReference{
+				SKU:        inventory.SKU(line.SKU),
+				LocationID: inventory.LocationID(line.LocationID),
+			},
+			CartID:   inventory.CartID(req.HolderID),
+			Quantity: line.Quantity,
+			TTL:      ttl,
+		}); err != nil {
+			status := http.StatusInternalServerError
+			if errors.Is(err, inventory.ErrInsufficientInventory) {
+				status = http.StatusConflict
+			}
+			http.Error(w, err.Error(), status)
+			return
+		}
+	}
+	w.Header().Set("Content-Type", "application/json")
+	_ = json.NewEncoder(w).Encode(map[string]any{"status": "reserved", "holderId": req.HolderID})
+}
+
+func (srv *Server) releaseReservationHandler(w http.ResponseWriter, r *http.Request) {
+	var req reservationBatchReq
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+		http.Error(w, "invalid request body", http.StatusBadRequest)
+		return
+	}
+	if req.HolderID == "" {
+		http.Error(w, "missing holderId", http.StatusBadRequest)
+		return
+	}
+	if len(req.Lines) == 0 {
+		http.Error(w, "missing lines", http.StatusBadRequest)
+		return
+	}
+	for _, line := range req.Lines {
+		if line.SKU == "" || line.LocationID == "" {
+			http.Error(w, "each line must include sku and locationId", http.StatusBadRequest)
+			return
+		}
+		if err := srv.reservationService.ReleaseForCart(r.Context(),
+			inventory.SKU(line.SKU),
+			inventory.LocationID(line.LocationID),
+			inventory.CartID(req.HolderID),
+		); err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+	}
+	w.Header().Set("Content-Type", "application/json")
+	_ = json.NewEncoder(w).Encode(map[string]any{"status": "released", "holderId": req.HolderID})
+}

cmd/order/amqp_test.go

@@ -10,8 +10,8 @@ import (
 	"time"
 
 	"git.k6n.net/mats/go-cart-actor/pkg/actor"
-	"git.k6n.net/mats/go-cart-actor/pkg/idempotency"
 	"git.k6n.net/mats/go-cart-actor/pkg/flow"
+	"git.k6n.net/mats/go-cart-actor/pkg/idempotency"
 	"git.k6n.net/mats/go-cart-actor/pkg/order"
 )
 
@@ -41,10 +41,7 @@ func testServer(t *testing.T) *server {
 	applier := &orderedApplier{pool: pool, storage: storage}
 	provider := order.NewPassthroughProvider("legacy", "ref", 15000)
 
-	freg := flow.NewRegistry()
-	flow.RegisterBuiltinHooks(freg)
-	order.RegisterFlowActions(freg, applier, provider)
-	order.RegisterEmitHook(freg, nil)
+	freg := buildFlowRegistry(applier, provider, nil, nil, nil, nil, slog.New(slog.NewTextHandler(io.Discard, nil)))
 	engine := flow.NewEngine(freg, slog.New(slog.NewTextHandler(io.Discard, nil)))
 
 	def, err := order.EmbeddedFlow("place-and-pay")

cmd/order/custom_hooks.go

@@ -0,0 +1,68 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"log/slog"
+
+	"git.k6n.net/mats/go-cart-actor/pkg/flow"
+	"git.k6n.net/mats/go-cart-actor/pkg/order"
+)
+
+type projectFulfillmentHookParams struct {
+	Integration string `json:"integration,omitempty"`
+	Target      string `json:"target,omitempty"`
+	Dropship    bool   `json:"dropship,omitempty"`
+}
+
+// registerProjectFlowHooks is the project-layer seam for customer-specific flow
+// integrations. These belong here rather than pkg/order so core order logic
+// stays generic while deployments can register their own fulfillment tools.
+func registerProjectFlowHooks(reg *flow.Registry, app *orderedApplier, logger *slog.Logger) {
+	if logger == nil {
+		logger = slog.Default()
+	}
+	reg.HookWithMeta("project_fulfillment_integration", func(ctx context.Context, st *flow.State, info flow.HookInfo, params json.RawMessage) error {
+		var p projectFulfillmentHookParams
+		if len(params) > 0 {
+			if err := json.Unmarshal(params, &p); err != nil {
+				return fmt.Errorf("project_fulfillment_integration: bad params: %w", err)
+			}
+		}
+		if p.Integration == "" {
+			p.Integration = "order-integration"
+		}
+
+		o, err := app.Get(ctx, st.ID)
+		if err != nil {
+			return err
+		}
+		if len(o.Fulfillments) == 0 {
+			return fmt.Errorf("project_fulfillment_integration: order %s has no fulfillment yet", order.OrderId(st.ID).String())
+		}
+		last := o.Fulfillments[len(o.Fulfillments)-1]
+
+		log := st.Logger
+		if log == nil {
+			log = logger
+		}
+		log.Info("project fulfillment integration",
+			"orderId", order.OrderId(st.ID).String(),
+			"orderReference", o.OrderReference,
+			"customerEmail", o.CustomerEmail,
+			"integration", p.Integration,
+			"target", p.Target,
+			"dropship", p.Dropship,
+			"step", info.Step,
+			"phase", info.Phase,
+			"fulfillmentId", last.ID,
+			"carrier", last.Carrier,
+			"trackingNumber", last.TrackingNumber,
+		)
+		return nil
+	}, flow.CapabilityMeta{
+		Description:   "Project-specific fulfillment integration seam for local or testing adapters.",
+		ExampleParams: json.RawMessage(`{"integration":"dropship-test","target":"erp-sandbox","dropship":true}`),
+	})
+}

cmd/order/custom_hooks_test.go

@@ -0,0 +1,87 @@
+package main
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"log/slog"
+	"strings"
+	"testing"
+
+	"git.k6n.net/mats/go-cart-actor/pkg/flow"
+	"git.k6n.net/mats/go-cart-actor/pkg/order"
+	messages "git.k6n.net/mats/go-cart-actor/proto/order"
+)
+
+func TestProjectFulfillmentIntegrationHookIsRegistered(t *testing.T) {
+	s := testServer(t)
+	if !strings.Contains(strings.Join(s.freg.Capabilities().Hooks, ","), "project_fulfillment_integration") {
+		t.Fatalf("hooks = %v, want project_fulfillment_integration", s.freg.Capabilities().Hooks)
+	}
+}
+
+func TestProjectFulfillmentIntegrationLogs(t *testing.T) {
+	s := testServer(t)
+	var logs bytes.Buffer
+	logger := slog.New(slog.NewJSONHandler(&logs, nil))
+
+	provider := order.NewPassthroughProvider("legacy", "ref", 25000)
+	freg := buildFlowRegistry(s.applier, provider, nil, nil, nil, nil, logger)
+	engine := flow.NewEngine(freg, logger)
+
+	st := flow.NewState(801, logger)
+	po := orderTestPlaceMsg()
+	po.CustomerEmail = "dropship@example.com"
+	st.Vars[order.PlaceOrderVar] = po
+
+	def, err := order.EmbeddedFlow("place-and-pay")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if _, err := engine.Run(context.Background(), def, st); err != nil {
+		t.Fatal(err)
+	}
+
+	ship := &flow.Definition{Name: "ship", Steps: []flow.Step{{
+		Name:   "fulfill",
+		Action: "create_fulfillment",
+		Params: json.RawMessage(`{"carrier":"dropshipper","trackingNumber":"DS-123","lines":[{"reference":"l1","quantity":1}]}`),
+		Hooks: flow.Hooks{After: []flow.HookRef{{
+			Type:   "project_fulfillment_integration",
+			Params: json.RawMessage(`{"integration":"dropship-test","target":"erp-sandbox","dropship":true}`),
+		}}},
+	}}}
+	if _, err := engine.Run(context.Background(), ship, flow.NewState(801, logger)); err != nil {
+		t.Fatal(err)
+	}
+
+	got := logs.String()
+	for _, want := range []string{
+		`"msg":"project fulfillment integration"`,
+		`"integration":"dropship-test"`,
+		`"target":"erp-sandbox"`,
+		`"dropship":true`,
+		`"trackingNumber":"DS-123"`,
+	} {
+		if !strings.Contains(got, want) {
+			t.Fatalf("log output missing %s: %s", want, got)
+		}
+	}
+}
+
+func orderTestPlaceMsg() *messages.PlaceOrder {
+	return &messages.PlaceOrder{
+		OrderReference: "ref-1",
+		CartId:         "cart-1",
+		Currency:       "SEK",
+		Country:        "SE",
+		CustomerName:   "Dropship Customer",
+		TotalAmount:    25000,
+		TotalTax:       5000,
+		PlacedAtMs:     1718877600000,
+		Lines: []*messages.OrderLine{
+			{Reference: "l1", Sku: "ABC", Name: "Widget", Quantity: 2, UnitPrice: 10000, TaxRate: 25, TotalAmount: 20000},
+			{Reference: "l2", Sku: "DEF", Name: "Gizmo", Quantity: 1, UnitPrice: 5000, TaxRate: 25, TotalAmount: 5000},
+		},
+	}
+}

cmd/order/flow_registry.go

@@ -0,0 +1,29 @@
+package main
+
+import (
+	"log/slog"
+
+	"git.k6n.net/mats/go-cart-actor/pkg/flow"
+	"git.k6n.net/mats/go-cart-actor/pkg/order"
+)
+
+func buildFlowRegistry(
+	applier *orderedApplier,
+	provider order.PaymentProvider,
+	inventoryReservations order.InventoryReservationService,
+	emitPub order.Publisher,
+	emailSender order.EmailSender,
+	emailTemplates order.EmailTemplateStore,
+	logger *slog.Logger,
+) *flow.Registry {
+	freg := flow.NewRegistry()
+	flow.RegisterBuiltinHooks(freg)
+	order.RegisterFlowActions(freg, applier, provider)
+	order.RegisterInventoryReservationActions(freg, applier, inventoryReservations)
+	order.RegisterEmitHook(freg, emitPub)
+	order.RegisterEmailHook(freg, applier, emailSender, emailTemplates)
+	order.RegisterFulfillmentWebhookHook(freg, applier, nil)
+	order.RegisterOrderCreatedEmit(freg, applier, emitPub, "order", "order")
+	registerProjectFlowHooks(freg, applier, logger)
+	return freg
+}

cmd/order/handlers_checkout.go

@@ -120,11 +120,7 @@ func (s *server) createOrderFromCheckoutInternal(ctx context.Context, req *fromC
 		return 0, nil, nil, false, nil, fmt.Errorf("unknown flow %q", flowName)
 	}
 
-	freg := flow.NewRegistry()
-	flow.RegisterBuiltinHooks(freg)
-	order.RegisterFlowActions(freg, s.applier, provider)
-	order.RegisterEmitHook(freg, nil)
-
+	freg := buildFlowRegistry(s.applier, provider, s.inventoryReservations, nil, nil, nil, s.logger)
 	engine := flow.NewEngine(freg, s.logger)
 	st := flow.NewState(ordID, s.logger)
 	st.Vars[order.PlaceOrderVar] = po
@@ -178,6 +174,7 @@ func buildFromCheckoutPlaceOrder(id order.OrderId, req *fromCheckoutReq) *messag
 			TotalAmount: lineTotal,
 			TotalTax:    lineTax,
 			Location:    l.Location,
+			DropShip:    l.DropShip,
 		})
 	}
 	po.TotalAmount = total

cmd/order/main.go

@@ -12,6 +12,7 @@ import (
 	"log"
 	"log/slog"
 	"net/http"
+	"net/mail"
 	"os"
 	"path/filepath"
 	"strconv"
@@ -49,6 +50,7 @@ type server struct {
 	dataDir               string
 	idem                  *idempotency.Store
 	logger                *slog.Logger
+	inventoryReservations order.InventoryReservationService
 }
 
 func main() {
@@ -101,6 +103,18 @@ func main() {
 	// the broker (publisher is nil without AMQP — the hook then errors at run
 	// time, which is logged, not fatal).
 	amqpURL := os.Getenv("AMQP_URL")
+	emailTemplates, err := order.LoadEmailTemplates(config.EnvString("ORDER_EMAIL_TEMPLATES", "data/order-email-templates"))
+	if err != nil {
+		log.Fatalf("load email templates: %v", err)
+	}
+	emailSender, err := selectEmailSender(logger)
+	if err != nil {
+		log.Fatalf("configure email sender: %v", err)
+	}
+	inventoryReservations, err := selectInventoryReservationService()
+	if err != nil {
+		log.Fatalf("configure inventory reservation service: %v", err)
+	}
 	var emitPub order.Publisher
 	if amqpURL != "" {
 		// The amqp_emit hook writes to a durable outbox rather than the broker
@@ -138,13 +152,7 @@ func main() {
 			}
 		}
 	}
-	freg := flow.NewRegistry()
-	flow.RegisterBuiltinHooks(freg)
-	order.RegisterFlowActions(freg, applier, provider)
-	order.RegisterEmitHook(freg, emitPub)
-	// order.created domain event → durable outbox → "order" topic exchange.
-	// Reactors: inventory commit, fulfillment allocation.
-	order.RegisterOrderCreatedEmit(freg, applier, emitPub, "order", "order")
+	freg := buildFlowRegistry(applier, provider, inventoryReservations, emitPub, emailSender, emailTemplates, logger)
 	engine := flow.NewEngine(freg, logger)
 
 	def, err := order.EmbeddedFlow("place-and-pay")
@@ -171,6 +179,7 @@ func main() {
 		engine: engine, freg: freg, flows: flows, provider: provider,
 		taxProvider: taxProvider,
 		defaultFlow: def.Name, dataDir: dataDir, idem: idem, logger: logger,
+		inventoryReservations: inventoryReservations,
 	}
 
 	mux := http.NewServeMux()
@@ -278,6 +287,7 @@ type lineReq struct {
 	Quantity  int32  `json:"quantity"`
 	UnitPrice int64  `json:"unitPrice"` // inc-vat, minor units
 	TaxRate   int32  `json:"taxRate"`   // basis points (2500 = 25%)
+	DropShip  bool   `json:"drop_ship,omitempty"`
 	Location  string `json:"location,omitempty"` // inventory commit location / store id
 }
 
@@ -384,6 +394,7 @@ func (s *server) buildPlaceOrder(id order.OrderId, req *checkoutReq) *messages.P
 			TaxRate:     l.TaxRate,
 			TotalAmount: lineTotal,
 			TotalTax:    lineTax,
+			DropShip:    l.DropShip,
 		})
 	}
 	po.TotalAmount = total
@@ -502,7 +513,6 @@ func selectTaxProvider() tax.Provider {
 // the dependency-free mock; set PAYMENT_PROVIDER=stripe + STRIPE_SECRET_KEY for
 // real Stripe (STRIPE_API_BASE / STRIPE_PAYMENT_METHOD optionally override).
 func selectProvider(logger *slog.Logger) order.PaymentProvider {
-
 	if os.Getenv("PAYMENT_PROVIDER") == "stripe" {
 		key := os.Getenv("STRIPE_SECRET_KEY")
 		if key == "" {
@@ -515,6 +525,48 @@ func selectProvider(logger *slog.Logger) order.PaymentProvider {
 	return order.NewMockProvider()
 }
 
+// selectEmailSender picks the flow-email transport. SMTP is the only sender
+// implementation for now; when no SMTP host is configured the hook still exists
+// in capabilities but errors at run time if a flow tries to use it.
+func selectEmailSender(logger *slog.Logger) (order.EmailSender, error) {
+	kind := config.EnvString("ORDER_EMAIL_SENDER", "")
+	if kind == "" && os.Getenv("ORDER_EMAIL_SMTP_HOST") == "" {
+		return nil, nil
+	}
+	if kind == "" {
+		kind = "smtp"
+	}
+	if kind != "smtp" {
+		return nil, fmt.Errorf("unsupported ORDER_EMAIL_SENDER %q", kind)
+	}
+
+	fromAddr := strings.TrimSpace(os.Getenv("ORDER_EMAIL_FROM_ADDRESS"))
+	if fromAddr == "" {
+		return nil, fmt.Errorf("ORDER_EMAIL_FROM_ADDRESS is required when email sender is configured")
+	}
+	from := mail.Address{
+		Name:    strings.TrimSpace(os.Getenv("ORDER_EMAIL_FROM_NAME")),
+		Address: fromAddr,
+	}
+	sender, err := order.NewSMTPEmailSender(order.SMTPEmailSenderConfig{
+		Host:        config.EnvString("ORDER_EMAIL_SMTP_HOST", ""),
+		Port:        config.EnvInt("ORDER_EMAIL_SMTP_PORT", 587, func(n int) bool { return n > 0 }),
+		Username:    os.Getenv("ORDER_EMAIL_SMTP_USERNAME"),
+		Password:    os.Getenv("ORDER_EMAIL_SMTP_PASSWORD"),
+		DefaultFrom: from,
+		Timeout:     config.EnvDuration("ORDER_EMAIL_SMTP_TIMEOUT", 10*time.Second),
+	})
+	if err != nil {
+		return nil, err
+	}
+	logger.Info("email sender enabled", "kind", kind, "host", config.EnvString("ORDER_EMAIL_SMTP_HOST", ""), "from", from.Address)
+	return sender, nil
+}
+
+func selectInventoryReservationService() (order.InventoryReservationService, error) {
+	return order.NewHTTPInventoryReservationService(config.EnvString("INVENTORY_URL", "http://localhost:8080"), nil)
+}
+
 // loadUCPOrderSigner loads the UCP ECDSA signing key from the path specified in
 // the UCP_SIGNING_KEY_PATH environment variable. Returns nil if unset or unreadable.
 func loadUCPOrderSigner() *ucp.SigningConfig {

go.work.sum

@@ -127,6 +127,7 @@ github.com/golang/glog v1.2.5/go.mod h1:6AhwSGph0fcJtXVM/PEHPqZlFeoLxhs7/t5UDAwm
 github.com/golang/groupcache v0.0.0-20210331224755-41bb18bfe9da/go.mod h1:cIg4eruTrX1D+g88fzRXU5OdNfaM+9IcxsU14FzY7Hc=
 github.com/golang/snappy v0.0.4/go.mod h1:/XxbfmMg8lxefKM7IXC3fBNl/7bRcc72aCRzEWrmP2Q=
 github.com/google/btree v1.1.3/go.mod h1:qOPhT0dTNdNzV6Z/lhRX0YXUafgPLFUh+gZMl761Gm4=
+github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/google/go-pkcs11 v0.3.0/go.mod h1:6eQoGcuNJpa7jnd5pMGdkSaQpNDYvPlXWMcjXXThLlY=
 github.com/google/shlex v0.0.0-20191202100458-e7afc7fbc510/go.mod h1:pupxD2MaaD3pAXIBCelhxNneeOaAeabZDe5s4K6zSpQ=
 github.com/gorilla/mux v1.8.0/go.mod h1:DVbg23sWSpFRCP0SfiEN6jmj59UnW/n46BH5rLB71So=
@@ -152,8 +153,14 @@ github.com/xhit/go-str2duration/v2 v2.1.0/go.mod h1:ohY8p+0f07DiV6Em5LKB0s2YpLtX
 github.com/zeebo/assert v1.3.0/go.mod h1:Pq9JiuJQpG8JLJdtkwrJESF0Foym2/D9XMU5ciN/wJ0=
 github.com/zeebo/errs v1.4.0/go.mod h1:sgbWHsvVuTPHcqJJGQ1WhI5KbWlHYz+2+2C/LSEtCw4=
 go.opencensus.io v0.24.0/go.mod h1:vNK8G9p7aAivkbmorf4v+7Hgx+Zs0yY+0fOtgBfjQKo=
+golang.org/x/crypto v0.51.0/go.mod h1:8AdwkbraGNABw2kOX6YFPs3WM22XqI4EXEd8g+x7Oc8=
+golang.org/x/mod v0.36.0/go.mod h1:moc6ELqsWcOw5Ef3xVprK5ul/MvtVvkIXLziUOICjUQ=
+golang.org/x/net v0.54.0/go.mod h1:Sj4oj8jK6XmHpBZU/zWHw3BV3abl4Kvi+Ut7cQcY+cQ=
 golang.org/x/sys v0.30.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+golang.org/x/sys v0.44.0/go.mod h1:4GL1E5IUh+htKOUEOaiffhrAeqysfVGipDYzABqnCmw=
 golang.org/x/telemetry v0.0.0-20260409153401-be6f6cb8b1fa/go.mod h1:kHjTxDEnAu6/Nl9lDkzjWpR+bmKfxeiRuSDlsMb70gE=
+golang.org/x/telemetry v0.0.0-20260508192327-42602be52be6/go.mod h1:Eqhaxk/wZsWEH8CRxLwj6xzEJbz7k1EFGqx7nyCoabE=
+golang.org/x/tools v0.45.0/go.mod h1:LuUGqqaXcXMEFEruIVJVm5mgDD8vww/z/SR1gQ4uE/0=
 golang.org/x/tools/go/expect v0.1.0-deprecated/go.mod h1:eihoPOH+FgIqa3FpoTwguz/bVUSGBlGQU67vpBeOrBY=
 golang.org/x/tools/go/packages/packagestest v0.1.1-deprecated/go.mod h1:RVAQXBGNv1ib0J382/DPCRS/BPnsGebyM1Gj5VSDpG8=
 google.golang.org/appengine v1.6.8/go.mod h1:1jJ3jBArFh5pcgW8gCtRJnepW8FzD1V44FJffLiz/Ds=

internal/ucp/checkout.go

@@ -451,6 +451,8 @@ type orderLine struct {
 	Quantity  int32       `json:"quantity"`
 	UnitPrice money.Cents `json:"unitPrice"`
 	TaxRate   int32       `json:"taxRate"`
+	DropShip  bool        `json:"drop_ship,omitempty"`
+	Location  string      `json:"location,omitempty"`
 }
 
 type orderPayment struct {
@@ -549,6 +551,10 @@ func buildOrderLines(g *checkout.CheckoutGrain) []orderLine {
 		if it.Meta != nil {
 			name = it.Meta.Name
 		}
+		location := ""
+		if it.StoreId != nil {
+			location = *it.StoreId
+		}
 		lines = append(lines, orderLine{
 			Reference: it.Sku,
 			Sku:       it.Sku,
@@ -558,6 +564,8 @@ func buildOrderLines(g *checkout.CheckoutGrain) []orderLine {
 			// CartItem.Tax and OrderLine.TaxRate share the platform basis-point scale
 			// (2500 = 25%), so the rate passes through unchanged.
 			TaxRate:   int32(it.Tax),
+			DropShip:  it.DropShip,
+			Location:  location,
 		})
 	}
 	for _, d := range g.Deliveries {

pkg/backofficeadmin/app.go

@@ -12,7 +12,6 @@ package backofficeadmin
 
 import (
 	"context"
-	"encoding/json"
 	"log"
 	"net/http"
 	"os"
@@ -22,10 +21,8 @@ import (
 	"git.k6n.net/mats/go-cart-actor/pkg/cart"
 	"git.k6n.net/mats/go-cart-actor/pkg/checkout"
 	"git.k6n.net/mats/go-cart-actor/pkg/profile"
-	"git.k6n.net/mats/go-redis-inventory/pkg/inventory"
 	"git.k6n.net/mats/platform/rabbit"
 	amqp "github.com/rabbitmq/amqp091-go"
-	"github.com/redis/go-redis/v9"
 )
 
 // CartFileInfo is the metadata returned by the cart listing endpoint.
@@ -52,9 +49,6 @@ type Config struct {
 	CheckoutDataDir string
 	// ProfileDataDir holds the profile event logs (optional, default "" — customer endpoints disabled).
 	ProfileDataDir string
-	// RedisAddress / RedisPassword reach the inventory store.
-	RedisAddress  string
-	RedisPassword string
 }
 
 // App is the commerce admin control plane. Construct with New, register its
@@ -62,15 +56,15 @@ type Config struct {
 type App struct {
 	fs  *FileServer
 	hub *Hub
-	rdb *redis.Client
-	inv *inventory.RedisInventoryService
 	cs  *CustomerServer
 }
 
-// New constructs the commerce admin: it opens the Redis inventory service, the
-// cart/checkout disk event-log stores, the file server, and the WebSocket hub.
-// It does not register routes (RegisterRoutes), start background work (Start),
-// or open a listener.
+// New constructs the commerce admin: it opens the cart/checkout disk event-log
+// stores, the file server, and the WebSocket hub. It does not register routes
+// (RegisterRoutes), start background work (Start), or open a listener.
+//
+// Inventory writes no longer live here — they go through the standalone inventory
+// service's HTTP API (/api/inventory/batch), reverse-proxied by the host.
 func New(cfg Config) (*App, error) {
 	if cfg.DataDir == "" {
 		cfg.DataDir = "data"
@@ -79,16 +73,6 @@ func New(cfg Config) (*App, error) {
 		cfg.CheckoutDataDir = "checkout-data"
 	}
 
-	rdb := redis.NewClient(&redis.Options{
-		Addr:     cfg.RedisAddress,
-		Password: cfg.RedisPassword,
-		DB:       0,
-	})
-	inventoryService, err := inventory.NewRedisInventoryService(rdb)
-	if err != nil {
-		return nil, err
-	}
-
 	_ = os.MkdirAll(cfg.DataDir, 0755)
 	reg := cart.NewCartMultationRegistry(cart.NewCartMutationContext(nil))
 	diskStorage := actor.NewDiskStorage[cart.CartGrain](cfg.DataDir, reg)
@@ -109,8 +93,6 @@ func New(cfg Config) (*App, error) {
 	return &App{
 		fs:  NewFileServer(cfg.DataDir, cfg.CheckoutDataDir, diskStorage, diskStorageCheckout),
 		hub: NewHub(),
-		rdb: rdb,
-		inv: inventoryService,
 		cs:  customerSrv,
 	}, nil
 }
@@ -123,7 +105,6 @@ func (a *App) RegisterRoutes(mux *http.ServeMux) {
 	mux.HandleFunc("GET /cart/{id}", a.fs.CartHandler)
 	mux.HandleFunc("GET /checkouts", a.fs.CheckoutsHandler)
 	mux.HandleFunc("GET /checkout/{id}", a.fs.CheckoutHandler)
-	mux.HandleFunc("PUT /inventory/{locationId}/{sku}", a.updateInventory)
 	mux.HandleFunc("/promotions", a.fs.PromotionsHandler)
 	mux.HandleFunc("/vouchers", a.fs.VoucherHandler)
 	mux.HandleFunc("/promotion/{id}", a.fs.PromotionPartHandler)
@@ -134,28 +115,7 @@ func (a *App) RegisterRoutes(mux *http.ServeMux) {
 	}
 }
 
-func (a *App) updateInventory(w http.ResponseWriter, r *http.Request) {
-	locationID := inventory.LocationID(r.PathValue("locationId"))
-	sku := inventory.SKU(r.PathValue("sku"))
-	pipe := a.rdb.Pipeline()
-	var payload struct {
-		Quantity int64 `json:"quantity"`
-	}
-	if err := json.NewDecoder(r.Body).Decode(&payload); err != nil {
-		http.Error(w, "invalid payload", http.StatusBadRequest)
-		return
-	}
-	a.inv.UpdateInventory(r.Context(), pipe, sku, locationID, payload.Quantity)
-	if _, err := pipe.Exec(r.Context()); err != nil {
-		http.Error(w, "failed to update inventory", http.StatusInternalServerError)
-		return
-	}
-	if err := a.inv.SendInventoryChanged(r.Context(), sku, locationID); err != nil {
-		w.WriteHeader(http.StatusBadRequest)
-		return
-	}
-	w.WriteHeader(http.StatusOK)
-}
+
 
 // Start runs the WebSocket hub loop and, when conn is non-nil, the RabbitMQ
 // mutation consumer that broadcasts cart mutations to connected clients. The
@@ -169,10 +129,10 @@ func (a *App) Start(ctx context.Context, conn *rabbit.Conn) error {
 	return nil
 }
 
-// Shutdown releases the App's resources (the Redis client). The background
-// goroutines are stopped by cancelling the ctx passed to Start.
+// Shutdown releases the App's resources. The background goroutines are stopped
+// by cancelling the ctx passed to Start.
 func (a *App) Shutdown(_ context.Context) error {
-	return a.rdb.Close()
+	return nil
 }
 
 // startMutationConsumer subscribes to the cart "mutation" topic and forwards

pkg/cart/cart-mutation-helper.go

@@ -5,14 +5,14 @@ import (
 	"time"
 
 	"git.k6n.net/mats/go-cart-actor/pkg/actor"
-	"git.k6n.net/mats/go-redis-inventory/pkg/inventory"
+	"git.k6n.net/mats/platform/inventory"
 )
 
 type CartMutationContext struct {
-	reservationService inventory.CartReservationService
+	reservationService inventory.ReservationPolicy
 }
 
-func NewCartMutationContext(reservationService inventory.CartReservationService) *CartMutationContext {
+func NewCartMutationContext(reservationService inventory.ReservationPolicy) *CartMutationContext {
 	return &CartMutationContext{
 		reservationService: reservationService,
 	}
@@ -30,7 +30,7 @@ func (c *CartMutationContext) ReserveItem(ctx context.Context, cartId CartId, sk
 	}
 	ttl := time.Minute * 15
 	endTime := time.Now().Add(ttl)
-	err := c.reservationService.ReserveForCart(ctx, inventory.CartReserveRequest{
+	err := c.reservationService.Reserve(ctx, inventory.CartReserveRequest{
 		CartID: inventory.CartID(cartId.String()),
 		InventoryReference: &inventory.InventoryReference{
 			SKU:        inventory.SKU(sku),
@@ -57,7 +57,7 @@ func (c *CartMutationContext) UseReservations(item *CartItem) bool {
 	if item.InventoryTracked {
 		return true
 	}
-	return item.Cgm == "55010"
+	return false
 }
 
 func (c *CartMutationContext) ReleaseItem(ctx context.Context, cartId CartId, sku string, locationId *string) error {
@@ -68,7 +68,7 @@ func (c *CartMutationContext) ReleaseItem(ctx context.Context, cartId CartId, sk
 	if locationId != nil {
 		l = inventory.LocationID(*locationId)
 	}
-	return c.reservationService.ReleaseForCart(ctx, inventory.SKU(sku), l, inventory.CartID(cartId.String()))
+	return c.reservationService.Release(ctx, inventory.SKU(sku), l, inventory.CartID(cartId.String()))
 }
 
 func NewCartMultationRegistry(context *CartMutationContext) actor.MutationRegistry {

pkg/flow/engine.go

@@ -54,42 +54,78 @@ type HookInfo struct {
 // — so observability/notification hooks can't break the business transaction.
 type Hook func(ctx context.Context, st *State, info HookInfo, params json.RawMessage) error
 
+// CapabilityMeta is the editor-facing documentation attached at registration
+// time. The server generates `/sagas/capabilities` from these registrations, so
+// UIs should consume this payload instead of hardcoding per-tool help.
+//
+// Register every action/predicate/hook with the matching *WithMeta helper when
+// it should be discoverable in editors. ExampleParams is arbitrary JSON shown as
+// a starter payload for params-capable tools.
+type CapabilityMeta struct {
+	Description   string          `json:"description,omitempty"`
+	ExampleParams json.RawMessage `json:"exampleParams,omitempty"`
+}
+
 // Registry holds the named actions, predicates and hooks a flow can reference.
 type Registry struct {
 	mu            sync.RWMutex
 	actions       map[string]Action
+	actionMeta    map[string]CapabilityMeta
 	predicates    map[string]Predicate
+	predicateMeta map[string]CapabilityMeta
 	hooks         map[string]Hook
+	hookMeta      map[string]CapabilityMeta
 }
 
 // NewRegistry returns an empty registry.
 func NewRegistry() *Registry {
 	return &Registry{
 		actions:       map[string]Action{},
+		actionMeta:    map[string]CapabilityMeta{},
 		predicates:    map[string]Predicate{},
+		predicateMeta: map[string]CapabilityMeta{},
 		hooks:         map[string]Hook{},
+		hookMeta:      map[string]CapabilityMeta{},
 	}
 }
 
 // Action registers an action under name (overwrites an existing one).
 func (r *Registry) Action(name string, fn Action) {
+	r.ActionWithMeta(name, fn, CapabilityMeta{})
+}
+
+// ActionWithMeta registers an action plus the metadata editors should display.
+func (r *Registry) ActionWithMeta(name string, fn Action, meta CapabilityMeta) {
 	r.mu.Lock()
 	defer r.mu.Unlock()
 	r.actions[name] = fn
+	r.actionMeta[name] = meta
 }
 
 // Predicate registers a predicate under name.
 func (r *Registry) Predicate(name string, fn Predicate) {
+	r.PredicateWithMeta(name, fn, CapabilityMeta{})
+}
+
+// PredicateWithMeta registers a predicate plus the metadata editors should display.
+func (r *Registry) PredicateWithMeta(name string, fn Predicate, meta CapabilityMeta) {
 	r.mu.Lock()
 	defer r.mu.Unlock()
 	r.predicates[name] = fn
+	r.predicateMeta[name] = meta
 }
 
 // Hook registers a hook under name.
 func (r *Registry) Hook(name string, fn Hook) {
+	r.HookWithMeta(name, fn, CapabilityMeta{})
+}
+
+// HookWithMeta registers a hook plus the metadata editors should display.
+func (r *Registry) HookWithMeta(name string, fn Hook, meta CapabilityMeta) {
 	r.mu.Lock()
 	defer r.mu.Unlock()
 	r.hooks[name] = fn
+	r.hookMeta[name] = meta
 }
 
 func (r *Registry) action(name string) (Action, bool) {
@@ -117,8 +153,11 @@ func (r *Registry) hook(name string) (Hook, bool) {
 // offer exactly the actions/predicates/hooks a flow may reference.
 type Capabilities struct {
 	Actions       []string                  `json:"actions"`
+	ActionMeta    map[string]CapabilityMeta `json:"actionMeta,omitempty"`
 	Predicates    []string                  `json:"predicates"`
+	PredicateMeta map[string]CapabilityMeta `json:"predicateMeta,omitempty"`
 	Hooks         []string                  `json:"hooks"`
+	HookMeta      map[string]CapabilityMeta `json:"hookMeta,omitempty"`
 }
 
 // Capabilities returns the sorted registered names.
@@ -127,11 +166,22 @@ func (r *Registry) Capabilities() Capabilities {
 	defer r.mu.RUnlock()
 	return Capabilities{
 		Actions:       sortedKeys(r.actions),
+		ActionMeta:    cloneMeta(r.actionMeta),
 		Predicates:    sortedKeys(r.predicates),
+		PredicateMeta: cloneMeta(r.predicateMeta),
 		Hooks:         sortedKeys(r.hooks),
+		HookMeta:      cloneMeta(r.hookMeta),
 	}
 }
 
+func cloneMeta(in map[string]CapabilityMeta) map[string]CapabilityMeta {
+	out := make(map[string]CapabilityMeta, len(in))
+	for k, v := range in {
+		out[k] = v
+	}
+	return out
+}
+
 func sortedKeys[V any](m map[string]V) []string {
 	out := make([]string, 0, len(m))
 	for k := range m {

pkg/flow/hooks.go

@@ -13,9 +13,17 @@ import (
 // (structured log line) and "webhook" (HTTP POST of the event). Domain packages
 // register their own hooks (e.g. "amqp_emit") on the same registry.
 func RegisterBuiltinHooks(reg *Registry) {
-	reg.Hook("log", logHook)
-	reg.Hook("noop", func(context.Context, *State, HookInfo, json.RawMessage) error { return nil })
-	reg.Hook("webhook", webhookHook(&http.Client{Timeout: 10 * time.Second}))
+	reg.HookWithMeta("log", logHook, CapabilityMeta{
+		Description:   "Write a structured log line for the current step and phase.",
+		ExampleParams: json.RawMessage(`{"message":"payment captured"}`),
+	})
+	reg.HookWithMeta("noop", func(context.Context, *State, HookInfo, json.RawMessage) error { return nil }, CapabilityMeta{
+		Description: "Do nothing. Useful as a placeholder while shaping a flow.",
+	})
+	reg.HookWithMeta("webhook", webhookHook(&http.Client{Timeout: 10 * time.Second}), CapabilityMeta{
+		Description:   "POST the flow event payload to an external HTTP endpoint.",
+		ExampleParams: json.RawMessage(`{"url":"https://example.test/order-events","headers":{"X-Flow":"place-and-pay"}}`),
+	})
 }
 
 // logHook emits a structured log line for the step/phase. Params (optional):

pkg/order/actions.go

@@ -64,7 +64,7 @@ const PlaceOrderVar = "placeOrder"
 // grain through app and taking payment via provider. Compose with
 // flow.RegisterBuiltinHooks(reg) to get the "log"/"webhook" hooks too.
 func RegisterFlowActions(reg *flow.Registry, app Applier, provider PaymentProvider) {
-	reg.Action("place_order", func(ctx context.Context, st *flow.State, _ json.RawMessage) error {
+	reg.ActionWithMeta("place_order", func(ctx context.Context, st *flow.State, _ json.RawMessage) error {
 		po, ok := st.Vars[PlaceOrderVar].(*messages.PlaceOrder)
 		if !ok || po == nil {
 			return fmt.Errorf("place_order: flow var %q is not a *PlaceOrder", PlaceOrderVar)
@@ -78,9 +78,9 @@ func RegisterFlowActions(reg *flow.Registry, app Applier, provider PaymentProvid
 		st.Vars["currency"] = po.GetCurrency()
 		st.Vars["orderReference"] = po.GetOrderReference()
 		return nil
-	})
+	}, flow.CapabilityMeta{Description: "Create the order from the flow state variable `placeOrder`."})
 
-	reg.Action("authorize_payment", func(ctx context.Context, st *flow.State, _ json.RawMessage) error {
+	reg.ActionWithMeta("authorize_payment", func(ctx context.Context, st *flow.State, _ json.RawMessage) error {
 		o, err := app.Get(ctx, st.ID)
 		if err != nil {
 			return err
@@ -101,9 +101,9 @@ func RegisterFlowActions(reg *flow.Registry, app Applier, provider PaymentProvid
 		st.Vars["authProvider"] = auth.Provider
 		st.Vars["authAmount"] = auth.Amount
 		return nil
-	})
+	}, flow.CapabilityMeta{Description: "Authorize payment with the configured provider."})
 
-	reg.Action("capture_payment", func(ctx context.Context, st *flow.State, _ json.RawMessage) error {
+	reg.ActionWithMeta("capture_payment", func(ctx context.Context, st *flow.State, _ json.RawMessage) error {
 		authRef, _ := st.Vars["authRef"].(string)
 		amount, _ := st.Vars["authAmount"].(int64)
 		if amount == 0 {
@@ -121,11 +121,11 @@ func RegisterFlowActions(reg *flow.Registry, app Applier, provider PaymentProvid
 			Reference: capture.Reference,
 			AtMs:      nowMs(),
 		})
-	})
+	}, flow.CapabilityMeta{Description: "Capture the authorized payment."})
 
 	// void_payment is the compensation for authorize_payment: void with the
 	// provider and cancel the order if it is still in a cancellable state.
-	reg.Action("void_payment", func(ctx context.Context, st *flow.State, _ json.RawMessage) error {
+	reg.ActionWithMeta("void_payment", func(ctx context.Context, st *flow.State, _ json.RawMessage) error {
 		if authRef, ok := st.Vars["authRef"].(string); ok && authRef != "" {
 			if err := provider.Void(ctx, authRef); err != nil {
 				return err
@@ -134,9 +134,9 @@ func RegisterFlowActions(reg *flow.Registry, app Applier, provider PaymentProvid
 		// Best-effort cancel; ignore if no longer cancellable.
 		_, _ = app.Apply(ctx, st.ID, &messages.CancelOrder{Reason: "compensation: payment voided", AtMs: nowMs()})
 		return nil
-	})
+	}, flow.CapabilityMeta{Description: "Void the authorization and cancel the order as compensation."})
 
-	reg.Action("cancel_order", func(ctx context.Context, st *flow.State, params json.RawMessage) error {
+	reg.ActionWithMeta("cancel_order", func(ctx context.Context, st *flow.State, params json.RawMessage) error {
 		reason := "cancelled"
 		if len(params) > 0 {
 			var p struct {
@@ -147,9 +147,12 @@ func RegisterFlowActions(reg *flow.Registry, app Applier, provider PaymentProvid
 			}
 		}
 		return applyOne(ctx, app, st.ID, &messages.CancelOrder{Reason: reason, AtMs: nowMs()})
+	}, flow.CapabilityMeta{
+		Description:   "Cancel the order with an optional reason.",
+		ExampleParams: json.RawMessage(`{"reason":"customer requested cancellation"}`),
 	})
 
-	reg.Action("issue_refund", func(ctx context.Context, st *flow.State, params json.RawMessage) error {
+	reg.ActionWithMeta("issue_refund", func(ctx context.Context, st *flow.State, params json.RawMessage) error {
 		o, err := app.Get(ctx, st.ID)
 		if err != nil {
 			return err
@@ -180,6 +183,64 @@ func RegisterFlowActions(reg *flow.Registry, app Applier, provider PaymentProvid
 			Reference: ref.Reference,
 			AtMs:      nowMs(),
 		})
+	}, flow.CapabilityMeta{
+		Description:   "Refund the remaining or specified captured amount.",
+		ExampleParams: json.RawMessage(`{"amount":2500}`),
+	})
+
+	reg.ActionWithMeta("create_fulfillment", func(ctx context.Context, st *flow.State, params json.RawMessage) error {
+		var p struct {
+			ID             string `json:"id"`
+			Carrier        string `json:"carrier,omitempty"`
+			TrackingNumber string `json:"trackingNumber,omitempty"`
+			TrackingURI    string `json:"trackingUri,omitempty"`
+			AtMs           int64  `json:"atMs,omitempty"`
+			Lines          []struct {
+				Reference string `json:"reference"`
+				Quantity  int32  `json:"quantity"`
+			} `json:"lines"`
+		}
+		if err := json.Unmarshal(params, &p); err != nil {
+			return fmt.Errorf("create_fulfillment: bad params: %w", err)
+		}
+		if len(p.Lines) == 0 {
+			return fmt.Errorf("create_fulfillment: missing lines")
+		}
+		id := p.ID
+		if id == "" {
+			fid, err := NewOrderId()
+			if err != nil {
+				return err
+			}
+			id = "f_" + fid.String()
+		}
+		atMs := p.AtMs
+		if atMs == 0 {
+			atMs = nowMs()
+		}
+		msg := &messages.CreateFulfillment{
+			Id:             id,
+			Carrier:        p.Carrier,
+			TrackingNumber: p.TrackingNumber,
+			TrackingUri:    p.TrackingURI,
+			AtMs:           atMs,
+		}
+		for _, line := range p.Lines {
+			if line.Reference == "" {
+				return fmt.Errorf("create_fulfillment: line missing reference")
+			}
+			if line.Quantity <= 0 {
+				return fmt.Errorf("create_fulfillment: line %q has invalid quantity %d", line.Reference, line.Quantity)
+			}
+			msg.Lines = append(msg.Lines, &messages.FulfillmentLine{
+				Reference: line.Reference,
+				Quantity:  line.Quantity,
+			})
+		}
+		return applyOne(ctx, app, st.ID, msg)
+	}, flow.CapabilityMeta{
+		Description:   "Create a shipment / fulfillment and advance the order fulfillment status.",
+		ExampleParams: json.RawMessage(`{"carrier":"dropshipper","trackingNumber":"TRACK-123","trackingUri":"https://tracking.example/TRACK-123","lines":[{"reference":"l1","quantity":1}]}`),
 	})
 
 	registerPredicates(reg, app)
@@ -193,39 +254,39 @@ func RegisterFlowActions(reg *flow.Registry, app Applier, provider PaymentProvid
 func registerPredicates(reg *flow.Registry, app Applier) {
 	get := func(ctx context.Context, st *flow.State) (*OrderGrain, error) { return app.Get(ctx, st.ID) }
 
-	reg.Predicate("has_customer_email", func(ctx context.Context, st *flow.State) (bool, error) {
+	reg.PredicateWithMeta("has_customer_email", func(ctx context.Context, st *flow.State) (bool, error) {
 		o, err := get(ctx, st)
 		if err != nil {
 			return false, err
 		}
 		return o.CustomerEmail != "", nil
-	})
-	reg.Predicate("has_items", func(ctx context.Context, st *flow.State) (bool, error) {
+	}, flow.CapabilityMeta{Description: "Run only when the order has a customer email address."})
+	reg.PredicateWithMeta("has_items", func(ctx context.Context, st *flow.State) (bool, error) {
 		o, err := get(ctx, st)
 		if err != nil {
 			return false, err
 		}
 		return len(o.Lines) > 0, nil
-	})
-	reg.Predicate("is_captured", func(ctx context.Context, st *flow.State) (bool, error) {
+	}, flow.CapabilityMeta{Description: "Run only when the order contains at least one line item."})
+	reg.PredicateWithMeta("is_captured", func(ctx context.Context, st *flow.State) (bool, error) {
 		o, err := get(ctx, st)
 		if err != nil {
 			return false, err
 		}
 		return o.Status == StatusCaptured, nil
-	})
-	reg.Predicate("not_captured", func(ctx context.Context, st *flow.State) (bool, error) {
+	}, flow.CapabilityMeta{Description: "Run only after payment has been captured."})
+	reg.PredicateWithMeta("not_captured", func(ctx context.Context, st *flow.State) (bool, error) {
 		o, err := get(ctx, st)
 		if err != nil {
 			return false, err
 		}
 		return o.Status != StatusCaptured, nil
-	})
-	reg.Predicate("has_open_balance", func(ctx context.Context, st *flow.State) (bool, error) {
+	}, flow.CapabilityMeta{Description: "Run only before payment is captured."})
+	reg.PredicateWithMeta("has_open_balance", func(ctx context.Context, st *flow.State) (bool, error) {
 		o, err := get(ctx, st)
 		if err != nil {
 			return false, err
 		}
 		return o.CapturedAmount-o.RefundedAmount > 0, nil
-	})
+	}, flow.CapabilityMeta{Description: "Run only when captured amount remains to refund."})
 }

pkg/order/capabilities_test.go

@@ -3,19 +3,28 @@ package order
 import (
 	"context"
 	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"net/mail"
 	"slices"
 	"strings"
 	"testing"
+	"time"
 
 	"git.k6n.net/mats/go-cart-actor/pkg/flow"
 )
 
 func fullRegistry(t *testing.T, pub Publisher) *flow.Registry {
 	t.Helper()
+	pool := newPool(t)
 	reg := flow.NewRegistry()
 	flow.RegisterBuiltinHooks(reg)
-	RegisterFlowActions(reg, newPool(t), NewMockProvider())
+	RegisterFlowActions(reg, pool, NewMockProvider())
+	RegisterInventoryReservationActions(reg, pool, nil)
 	RegisterEmitHook(reg, pub)
+	RegisterEmailHook(reg, pool, nil, nil)
+	RegisterFulfillmentWebhookHook(reg, pool, nil)
 	return reg
 }
 
@@ -30,6 +39,92 @@ func TestCapabilitiesIncludesPredicatesAndEmit(t *testing.T) {
 	if !slices.Contains(caps.Hooks, "amqp_emit") {
 		t.Errorf("hooks missing amqp_emit (got %v)", caps.Hooks)
 	}
+	if !slices.Contains(caps.Hooks, "send_email") {
+		t.Errorf("hooks missing send_email (got %v)", caps.Hooks)
+	}
+	if !slices.Contains(caps.Hooks, "fulfillment_webhook") {
+		t.Errorf("hooks missing fulfillment_webhook (got %v)", caps.Hooks)
+	}
+	if !slices.Contains(caps.Actions, "create_fulfillment") {
+		t.Errorf("actions missing create_fulfillment (got %v)", caps.Actions)
+	}
+	if !slices.Contains(caps.Actions, "reserve_inventory") {
+		t.Errorf("actions missing reserve_inventory (got %v)", caps.Actions)
+	}
+	if !slices.Contains(caps.Actions, "release_inventory") {
+		t.Errorf("actions missing release_inventory (got %v)", caps.Actions)
+	}
+	if caps.ActionMeta["create_fulfillment"].Description == "" {
+		t.Fatalf("action meta missing for create_fulfillment: %#v", caps.ActionMeta["create_fulfillment"])
+	}
+	if len(caps.HookMeta["fulfillment_webhook"].ExampleParams) == 0 {
+		t.Fatalf("hook meta missing example params for fulfillment_webhook: %#v", caps.HookMeta["fulfillment_webhook"])
+	}
+	if caps.PredicateMeta["has_customer_email"].Description == "" {
+		t.Fatalf("predicate meta missing for has_customer_email: %#v", caps.PredicateMeta["has_customer_email"])
+	}
+}
+
+type fakeInventoryReservationService struct {
+	reserved []InventoryReservationRequest
+	released []InventoryReservationRequest
+}
+
+func (f *fakeInventoryReservationService) Reserve(_ context.Context, req InventoryReservationRequest) error {
+	f.reserved = append(f.reserved, req)
+	return nil
+}
+
+func (f *fakeInventoryReservationService) Release(_ context.Context, req InventoryReservationRequest) error {
+	f.released = append(f.released, req)
+	return nil
+}
+
+func TestReserveInventoryActionBuildsReservationRequest(t *testing.T) {
+	pool := newPool(t)
+	reg := flow.NewRegistry()
+	RegisterFlowActions(reg, pool, NewMockProvider())
+	fake := &fakeInventoryReservationService{}
+	RegisterInventoryReservationActions(reg, pool, fake)
+	eng := flow.NewEngine(reg, nil)
+
+	const id = 703
+	st := flow.NewState(id, nil)
+	po := placeMsg()
+	st.Vars[PlaceOrderVar] = po
+	def, err := EmbeddedFlow("place-and-pay")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if _, err := eng.Run(context.Background(), def, st); err != nil {
+		t.Fatal(err)
+	}
+
+	reserve := &flow.Definition{Name: "reserve", Steps: []flow.Step{{
+		Name:   "reserve",
+		Action: "reserve_inventory",
+		Params: json.RawMessage(`{"ttlSeconds":600,"lines":[{"reference":"l1","quantity":1,"locationId":"se"}]}`),
+		Compensate: &flow.ActionRef{
+			Action: "release_inventory",
+			Params: json.RawMessage(`{"lines":[{"reference":"l1","quantity":1,"locationId":"se"}]}`),
+		},
+	}}}
+	if _, err := eng.Run(context.Background(), reserve, flow.NewState(id, nil)); err != nil {
+		t.Fatal(err)
+	}
+	if len(fake.reserved) != 1 {
+		t.Fatalf("reserved = %d, want 1", len(fake.reserved))
+	}
+	got := fake.reserved[0]
+	if got.HolderID != "order:"+OrderId(id).String() {
+		t.Fatalf("holderId = %q", got.HolderID)
+	}
+	if got.TTL != 10*time.Minute {
+		t.Fatalf("ttl = %s", got.TTL)
+	}
+	if len(got.Lines) != 1 || got.Lines[0].SKU != "ABC" || got.Lines[0].Quantity != 1 {
+		t.Fatalf("lines = %+v", got.Lines)
+	}
 }
 
 func TestIsCapturedPredicateGatesStep(t *testing.T) {
@@ -94,3 +189,148 @@ func TestAmqpEmitHookPublishes(t *testing.T) {
 		t.Fatalf("expected one message routed to k, got %v", fp.msgs)
 	}
 }
+
+type fakeEmailSender struct {
+	defaultFrom mail.Address
+	msgs        []EmailMessage
+}
+
+func (f *fakeEmailSender) DefaultFrom() mail.Address { return f.defaultFrom }
+
+func (f *fakeEmailSender) Send(_ context.Context, msg EmailMessage) error {
+	f.msgs = append(f.msgs, msg)
+	return nil
+}
+
+func TestSendEmailHookRendersFulfillmentTemplate(t *testing.T) {
+	pool := newPool(t)
+	reg := flow.NewRegistry()
+	RegisterFlowActions(reg, pool, NewMockProvider())
+
+	sender := &fakeEmailSender{defaultFrom: mail.Address{Name: "Ops", Address: "ops@example.com"}}
+	templates := newEmailTemplateCatalog(map[string]EmailTemplate{
+		"ship": {
+			Subject: "Order {{ .Order.OrderReference }} shipped",
+			Text:    "Tracking {{ .Fulfillment.TrackingNumber }} for {{ .Order.CustomerEmail }}",
+		},
+	})
+	RegisterEmailHook(reg, pool, sender, templates)
+	eng := flow.NewEngine(reg, nil)
+
+	const id = 701
+	st := flow.NewState(id, nil)
+	po := placeMsg()
+	po.CustomerEmail = "alice@example.com"
+	po.CustomerName = "Alice"
+	st.Vars[PlaceOrderVar] = po
+
+	def, err := EmbeddedFlow("place-and-pay")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if _, err := eng.Run(context.Background(), def, st); err != nil {
+		t.Fatal(err)
+	}
+
+	ship := &flow.Definition{Name: "ship", Steps: []flow.Step{{
+		Name:   "fulfill",
+		Action: "create_fulfillment",
+		Params: json.RawMessage(`{"carrier":"postnord","trackingNumber":"TRACK-123","trackingUri":"https://track.example/TRACK-123","lines":[{"reference":"l1","quantity":1}]}`),
+		Hooks:  flow.Hooks{After: []flow.HookRef{{Type: "send_email", Params: json.RawMessage(`{"template":"ship"}`)}}},
+	}}}
+	if _, err := eng.Run(context.Background(), ship, flow.NewState(id, nil)); err != nil {
+		t.Fatal(err)
+	}
+
+	if len(sender.msgs) != 1 {
+		t.Fatalf("sent %d emails, want 1", len(sender.msgs))
+	}
+	got := sender.msgs[0]
+	if got.From.Address != "ops@example.com" {
+		t.Fatalf("from = %q, want ops@example.com", got.From.Address)
+	}
+	if len(got.To) != 1 || got.To[0].Address != "alice@example.com" {
+		t.Fatalf("to = %+v, want alice@example.com", got.To)
+	}
+	if got.Subject != "Order ref-1 shipped" {
+		t.Fatalf("subject = %q", got.Subject)
+	}
+	if !strings.Contains(got.TextBody, "TRACK-123") {
+		t.Fatalf("text body = %q, want tracking number", got.TextBody)
+	}
+}
+
+func TestFulfillmentWebhookPostsOrderPayload(t *testing.T) {
+	pool := newPool(t)
+	reg := flow.NewRegistry()
+	RegisterFlowActions(reg, pool, NewMockProvider())
+
+	var gotMethod, gotPath, gotHeader string
+	var gotBody map[string]any
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		gotMethod = r.Method
+		gotPath = r.URL.Path
+		gotHeader = r.Header.Get("X-Integration")
+		if err := json.NewDecoder(r.Body).Decode(&gotBody); err != nil {
+			t.Fatalf("decode webhook body: %v", err)
+		}
+		w.WriteHeader(http.StatusAccepted)
+	}))
+	defer srv.Close()
+
+	RegisterFulfillmentWebhookHook(reg, pool, srv.Client())
+	eng := flow.NewEngine(reg, nil)
+
+	const id = 702
+	st := flow.NewState(id, nil)
+	po := placeMsg()
+	po.CustomerEmail = "dropship@example.com"
+	st.Vars[PlaceOrderVar] = po
+
+	def, err := EmbeddedFlow("place-and-pay")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if _, err := eng.Run(context.Background(), def, st); err != nil {
+		t.Fatal(err)
+	}
+
+	ship := &flow.Definition{Name: "ship", Steps: []flow.Step{{
+		Name:   "fulfill",
+		Action: "create_fulfillment",
+		Params: json.RawMessage(`{"carrier":"dropshipper","trackingNumber":"DS-123","lines":[{"reference":"l1","quantity":1}]}`),
+		Hooks: flow.Hooks{After: []flow.HookRef{{
+			Type: "fulfillment_webhook",
+			Params: json.RawMessage(fmt.Sprintf(`{
+				"url": %q,
+				"method": "POST",
+				"headers": {
+					"X-Integration": "dropship {{ .Order.OrderReference }}"
+				}
+			}`, srv.URL+`/hooks/{{ .OrderID }}`)),
+		}}},
+	}}}
+	if _, err := eng.Run(context.Background(), ship, flow.NewState(id, nil)); err != nil {
+		t.Fatal(err)
+	}
+
+	if gotMethod != http.MethodPost {
+		t.Fatalf("method = %q, want POST", gotMethod)
+	}
+	if gotPath != "/hooks/"+OrderId(id).String() {
+		t.Fatalf("path = %q", gotPath)
+	}
+	if gotHeader != "dropship ref-1" {
+		t.Fatalf("header = %q", gotHeader)
+	}
+	if gotBody["orderId"] != OrderId(id).String() {
+		t.Fatalf("body orderId = %v", gotBody["orderId"])
+	}
+	fulfillment, ok := gotBody["fulfillment"].(map[string]any)
+	if !ok {
+		t.Fatalf("body fulfillment missing: %#v", gotBody["fulfillment"])
+	}
+	if fulfillment["trackingNumber"] != "DS-123" {
+		t.Fatalf("trackingNumber = %v", fulfillment["trackingNumber"])
+	}
+}

pkg/order/email.go

@@ -0,0 +1,508 @@
+package order
+
+import (
+	"bytes"
+	"context"
+	"crypto/tls"
+	"embed"
+	"encoding/json"
+	"fmt"
+	htmltmpl "html/template"
+	"io/fs"
+	"mime"
+	"mime/quotedprintable"
+	"net"
+	"net/mail"
+	"net/smtp"
+	"os"
+	"path/filepath"
+	"strings"
+	texttmpl "text/template"
+	"time"
+
+	"git.k6n.net/mats/go-cart-actor/pkg/flow"
+)
+
+// EmailMessage is the rendered mail payload a sender delivers.
+type EmailMessage struct {
+	From     mail.Address
+	To       []mail.Address
+	Subject  string
+	TextBody string
+	HTMLBody string
+}
+
+// EmailSender delivers an already-rendered mail and exposes its default sender.
+type EmailSender interface {
+	Send(ctx context.Context, msg EmailMessage) error
+	DefaultFrom() mail.Address
+}
+
+// SMTPEmailSenderConfig configures the SMTP mail transport.
+type SMTPEmailSenderConfig struct {
+	Host        string
+	Port        int
+	Username    string
+	Password    string
+	DefaultFrom mail.Address
+	Timeout     time.Duration
+}
+
+type smtpEmailSender struct {
+	host        string
+	addr        string
+	auth        smtp.Auth
+	defaultFrom mail.Address
+	timeout     time.Duration
+}
+
+// NewSMTPEmailSender returns an SMTP-backed sender. It supports plain SMTP with
+// opportunistic STARTTLS, which is the only configured transport for now.
+func NewSMTPEmailSender(cfg SMTPEmailSenderConfig) (EmailSender, error) {
+	if strings.TrimSpace(cfg.Host) == "" {
+		return nil, fmt.Errorf("smtp sender: missing host")
+	}
+	if cfg.Port <= 0 {
+		return nil, fmt.Errorf("smtp sender: invalid port %d", cfg.Port)
+	}
+	if cfg.Timeout <= 0 {
+		cfg.Timeout = 10 * time.Second
+	}
+	if strings.TrimSpace(cfg.DefaultFrom.Address) == "" {
+		return nil, fmt.Errorf("smtp sender: missing default from address")
+	}
+	s := &smtpEmailSender{
+		host:        cfg.Host,
+		addr:        net.JoinHostPort(cfg.Host, fmt.Sprintf("%d", cfg.Port)),
+		defaultFrom: cfg.DefaultFrom,
+		timeout:     cfg.Timeout,
+	}
+	if cfg.Username != "" {
+		s.auth = smtp.PlainAuth("", cfg.Username, cfg.Password, cfg.Host)
+	}
+	return s, nil
+}
+
+func (s *smtpEmailSender) DefaultFrom() mail.Address { return s.defaultFrom }
+
+func (s *smtpEmailSender) Send(ctx context.Context, msg EmailMessage) error {
+	if strings.TrimSpace(msg.From.Address) == "" {
+		return fmt.Errorf("smtp sender: missing from address")
+	}
+	if len(msg.To) == 0 {
+		return fmt.Errorf("smtp sender: missing recipients")
+	}
+	if strings.TrimSpace(msg.Subject) == "" {
+		return fmt.Errorf("smtp sender: missing subject")
+	}
+	body, err := buildSMTPMessage(msg)
+	if err != nil {
+		return err
+	}
+
+	conn, err := (&net.Dialer{Timeout: s.timeout}).DialContext(ctx, "tcp", s.addr)
+	if err != nil {
+		return fmt.Errorf("smtp sender: dial %s: %w", s.addr, err)
+	}
+	defer conn.Close()
+	_ = conn.SetDeadline(time.Now().Add(s.timeout))
+
+	client, err := smtp.NewClient(conn, s.host)
+	if err != nil {
+		return fmt.Errorf("smtp sender: create client: %w", err)
+	}
+	defer client.Close()
+
+	if ok, _ := client.Extension("STARTTLS"); ok {
+		if err := client.StartTLS(&tls.Config{ServerName: s.host, MinVersion: tls.VersionTLS12}); err != nil {
+			return fmt.Errorf("smtp sender: starttls: %w", err)
+		}
+	}
+	if s.auth != nil {
+		if ok, _ := client.Extension("AUTH"); !ok {
+			return fmt.Errorf("smtp sender: server does not support auth")
+		}
+		if err := client.Auth(s.auth); err != nil {
+			return fmt.Errorf("smtp sender: auth: %w", err)
+		}
+	}
+	if err := client.Mail(msg.From.Address); err != nil {
+		return fmt.Errorf("smtp sender: mail from %s: %w", msg.From.Address, err)
+	}
+	for _, rcpt := range msg.To {
+		if err := client.Rcpt(rcpt.Address); err != nil {
+			return fmt.Errorf("smtp sender: rcpt to %s: %w", rcpt.Address, err)
+		}
+	}
+	w, err := client.Data()
+	if err != nil {
+		return fmt.Errorf("smtp sender: data: %w", err)
+	}
+	if _, err := w.Write(body); err != nil {
+		_ = w.Close()
+		return fmt.Errorf("smtp sender: write body: %w", err)
+	}
+	if err := w.Close(); err != nil {
+		return fmt.Errorf("smtp sender: close body: %w", err)
+	}
+	if err := client.Quit(); err != nil {
+		return fmt.Errorf("smtp sender: quit: %w", err)
+	}
+	return nil
+}
+
+func buildSMTPMessage(msg EmailMessage) ([]byte, error) {
+	if strings.TrimSpace(msg.TextBody) == "" && strings.TrimSpace(msg.HTMLBody) == "" {
+		return nil, fmt.Errorf("email: missing body")
+	}
+
+	var buf bytes.Buffer
+	writeHeader := func(name, value string) {
+		buf.WriteString(name)
+		buf.WriteString(": ")
+		buf.WriteString(value)
+		buf.WriteString("\r\n")
+	}
+	writeHeader("From", msg.From.String())
+	toList := make([]string, 0, len(msg.To))
+	for _, rcpt := range msg.To {
+		toList = append(toList, rcpt.String())
+	}
+	writeHeader("To", strings.Join(toList, ", "))
+	writeHeader("Subject", mime.QEncoding.Encode("utf-8", msg.Subject))
+	writeHeader("Date", time.Now().Format(time.RFC1123Z))
+	writeHeader("MIME-Version", "1.0")
+
+	switch {
+	case msg.TextBody != "" && msg.HTMLBody != "":
+		boundary := fmt.Sprintf("alt-%d", time.Now().UnixNano())
+		writeHeader("Content-Type", fmt.Sprintf(`multipart/alternative; boundary="%s"`, boundary))
+		buf.WriteString("\r\n")
+		writeMIMEPart(&buf, boundary, "text/plain; charset=utf-8", msg.TextBody)
+		writeMIMEPart(&buf, boundary, "text/html; charset=utf-8", msg.HTMLBody)
+		buf.WriteString("--")
+		buf.WriteString(boundary)
+		buf.WriteString("--\r\n")
+	case msg.HTMLBody != "":
+		writeHeader("Content-Type", `text/html; charset=utf-8`)
+		writeHeader("Content-Transfer-Encoding", "quoted-printable")
+		buf.WriteString("\r\n")
+		if err := writeQuotedPrintable(&buf, msg.HTMLBody); err != nil {
+			return nil, fmt.Errorf("email: encode html body: %w", err)
+		}
+	default:
+		writeHeader("Content-Type", `text/plain; charset=utf-8`)
+		writeHeader("Content-Transfer-Encoding", "quoted-printable")
+		buf.WriteString("\r\n")
+		if err := writeQuotedPrintable(&buf, msg.TextBody); err != nil {
+			return nil, fmt.Errorf("email: encode text body: %w", err)
+		}
+	}
+	return buf.Bytes(), nil
+}
+
+func writeMIMEPart(buf *bytes.Buffer, boundary, contentType, body string) {
+	buf.WriteString("--")
+	buf.WriteString(boundary)
+	buf.WriteString("\r\n")
+	buf.WriteString("Content-Type: ")
+	buf.WriteString(contentType)
+	buf.WriteString("\r\n")
+	buf.WriteString("Content-Transfer-Encoding: quoted-printable\r\n\r\n")
+	_ = writeQuotedPrintable(buf, body)
+	buf.WriteString("\r\n")
+}
+
+func writeQuotedPrintable(buf *bytes.Buffer, body string) error {
+	w := quotedprintable.NewWriter(buf)
+	if _, err := w.Write([]byte(strings.ReplaceAll(body, "\n", "\r\n"))); err != nil {
+		return err
+	}
+	return w.Close()
+}
+
+// EmailTemplate is a named mail template, typically selected by a flow hook.
+type EmailTemplate struct {
+	Subject string `json:"subject"`
+	Text    string `json:"text,omitempty"`
+	HTML    string `json:"html,omitempty"`
+}
+
+func (t EmailTemplate) validate(name string) error {
+	if strings.TrimSpace(t.Subject) == "" {
+		return fmt.Errorf("email template %q: missing subject", name)
+	}
+	if strings.TrimSpace(t.Text) == "" && strings.TrimSpace(t.HTML) == "" {
+		return fmt.Errorf("email template %q: missing text/html body", name)
+	}
+	return nil
+}
+
+// EmailTemplateStore resolves a template by name.
+type EmailTemplateStore interface {
+	Get(name string) (EmailTemplate, error)
+}
+
+type emailTemplateCatalog struct {
+	templates map[string]EmailTemplate
+}
+
+func newEmailTemplateCatalog(seed map[string]EmailTemplate) *emailTemplateCatalog {
+	out := &emailTemplateCatalog{templates: make(map[string]EmailTemplate, len(seed))}
+	for name, tmpl := range seed {
+		out.templates[name] = tmpl
+	}
+	return out
+}
+
+func (c *emailTemplateCatalog) Get(name string) (EmailTemplate, error) {
+	tmpl, ok := c.templates[name]
+	if !ok {
+		return EmailTemplate{}, fmt.Errorf("unknown template %q", name)
+	}
+	return tmpl, nil
+}
+
+//go:embed email_templates/*.json
+var embeddedEmailTemplateFS embed.FS
+
+// LoadEmailTemplates returns the embedded templates overlaid by any JSON files in
+// dir (same precedence model as flow definitions: on-disk wins).
+func LoadEmailTemplates(dir string) (EmailTemplateStore, error) {
+	templates := map[string]EmailTemplate{}
+
+	matches, err := fs.Glob(embeddedEmailTemplateFS, "email_templates/*.json")
+	if err != nil {
+		return nil, fmt.Errorf("list embedded email templates: %w", err)
+	}
+	for _, match := range matches {
+		data, err := embeddedEmailTemplateFS.ReadFile(match)
+		if err != nil {
+			return nil, fmt.Errorf("read embedded email template %s: %w", match, err)
+		}
+		name := strings.TrimSuffix(filepath.Base(match), ".json")
+		tmpl, err := parseEmailTemplate(name, data)
+		if err != nil {
+			return nil, err
+		}
+		templates[name] = tmpl
+	}
+
+	if dir != "" {
+		if _, err := os.Stat(dir); err == nil {
+			files, err := filepath.Glob(filepath.Join(dir, "*.json"))
+			if err != nil {
+				return nil, fmt.Errorf("list email templates in %s: %w", dir, err)
+			}
+			for _, file := range files {
+				data, err := os.ReadFile(file)
+				if err != nil {
+					return nil, fmt.Errorf("read email template %s: %w", file, err)
+				}
+				name := strings.TrimSuffix(filepath.Base(file), ".json")
+				tmpl, err := parseEmailTemplate(name, data)
+				if err != nil {
+					return nil, err
+				}
+				templates[name] = tmpl
+			}
+		} else if !os.IsNotExist(err) {
+			return nil, fmt.Errorf("stat email template dir %s: %w", dir, err)
+		}
+	}
+
+	return newEmailTemplateCatalog(templates), nil
+}
+
+func parseEmailTemplate(name string, data []byte) (EmailTemplate, error) {
+	var tmpl EmailTemplate
+	if err := json.Unmarshal(data, &tmpl); err != nil {
+		return EmailTemplate{}, fmt.Errorf("parse email template %q: %w", name, err)
+	}
+	if err := tmpl.validate(name); err != nil {
+		return EmailTemplate{}, err
+	}
+	return tmpl, nil
+}
+
+type emailHookParams struct {
+	Template string `json:"template"`
+	To       string `json:"to,omitempty"`
+	From     string `json:"from,omitempty"`
+	Subject  string `json:"subject,omitempty"`
+}
+
+type flowTemplateData struct {
+	Order           *OrderGrain
+	OrderID         string
+	Step            string
+	Phase           flow.Phase
+	Error           string
+	Vars            map[string]any
+	Fulfillment     *Fulfillment
+	ShippingAddress any
+	BillingAddress  any
+}
+
+// RegisterEmailHook registers the "send_email" flow hook. It reads the current
+// order for template data, renders the named template, and delivers it through
+// the configured sender. Hook params:
+//
+//	{
+//	  "template": "fulfillment-shipped",
+//	  "to": "{{ .Order.CustomerEmail }}",
+//	  "from": "Warehouse <warehouse@example.com>"
+//	}
+func RegisterEmailHook(reg *flow.Registry, app Applier, sender EmailSender, templates EmailTemplateStore) {
+	reg.HookWithMeta("send_email", func(ctx context.Context, st *flow.State, info flow.HookInfo, params json.RawMessage) error {
+		if sender == nil {
+			return fmt.Errorf("send_email: no sender configured")
+		}
+		if templates == nil {
+			return fmt.Errorf("send_email: no template store configured")
+		}
+		var p emailHookParams
+		if len(params) > 0 {
+			if err := json.Unmarshal(params, &p); err != nil {
+				return fmt.Errorf("send_email: bad params: %w", err)
+			}
+		}
+		if p.Template == "" {
+			return fmt.Errorf("send_email: missing template")
+		}
+		o, err := app.Get(ctx, st.ID)
+		if err != nil {
+			return err
+		}
+		tmpl, err := templates.Get(p.Template)
+		if err != nil {
+			return fmt.Errorf("send_email: %w", err)
+		}
+		data := buildFlowTemplateData(o, st, info)
+
+		subjectSource := tmpl.Subject
+		if p.Subject != "" {
+			subjectSource = p.Subject
+		}
+		subject, err := renderTextTemplate("email-subject", subjectSource, data)
+		if err != nil {
+			return fmt.Errorf("send_email: render subject: %w", err)
+		}
+		textBody, err := renderOptionalTextTemplate("email-text", tmpl.Text, data)
+		if err != nil {
+			return fmt.Errorf("send_email: render text body: %w", err)
+		}
+		htmlBody, err := renderOptionalHTMLTemplate("email-html", tmpl.HTML, data)
+		if err != nil {
+			return fmt.Errorf("send_email: render html body: %w", err)
+		}
+
+		toSource := p.To
+		if strings.TrimSpace(toSource) == "" {
+			toSource = o.CustomerEmail
+		}
+		toRendered, err := renderTextTemplate("email-to", toSource, data)
+		if err != nil {
+			return fmt.Errorf("send_email: render recipient: %w", err)
+		}
+		recipients, err := mail.ParseAddressList(toRendered)
+		if err != nil {
+			return fmt.Errorf("send_email: parse recipient %q: %w", toRendered, err)
+		}
+		to := make([]mail.Address, 0, len(recipients))
+		for _, rcpt := range recipients {
+			to = append(to, *rcpt)
+		}
+
+		from := sender.DefaultFrom()
+		if strings.TrimSpace(p.From) != "" {
+			fromRendered, err := renderTextTemplate("email-from", p.From, data)
+			if err != nil {
+				return fmt.Errorf("send_email: render sender: %w", err)
+			}
+			parsed, err := mail.ParseAddress(strings.TrimSpace(fromRendered))
+			if err != nil {
+				return fmt.Errorf("send_email: parse sender %q: %w", fromRendered, err)
+			}
+			from = *parsed
+		}
+
+		return sender.Send(ctx, EmailMessage{
+			From:     from,
+			To:       to,
+			Subject:  subject,
+			TextBody: textBody,
+			HTMLBody: htmlBody,
+		})
+	}, flow.CapabilityMeta{
+		Description:   "Render a named email template and send it through the configured sender.",
+		ExampleParams: json.RawMessage(`{"template":"fulfillment-shipped","to":"{{ .Order.CustomerEmail }}","from":"Store <no-reply@example.com>"}`),
+	})
+}
+
+func buildFlowTemplateData(o *OrderGrain, st *flow.State, info flow.HookInfo) flowTemplateData {
+	errStr := ""
+	if info.Err != nil {
+		errStr = info.Err.Error()
+	}
+	var lastFulfillment *Fulfillment
+	if n := len(o.Fulfillments); n > 0 {
+		lastFulfillment = &o.Fulfillments[n-1]
+	}
+	return flowTemplateData{
+		Order:           o,
+		OrderID:         OrderId(st.ID).String(),
+		Step:            info.Step,
+		Phase:           info.Phase,
+		Error:           errStr,
+		Vars:            st.Vars,
+		Fulfillment:     lastFulfillment,
+		ShippingAddress: decodeEmailTemplateJSON(o.ShippingAddress),
+		BillingAddress:  decodeEmailTemplateJSON(o.BillingAddress),
+	}
+}
+
+func decodeEmailTemplateJSON(raw json.RawMessage) any {
+	if len(raw) == 0 {
+		return nil
+	}
+	var v any
+	if err := json.Unmarshal(raw, &v); err != nil {
+		return string(raw)
+	}
+	return v
+}
+
+func renderTextTemplate(name, src string, data any) (string, error) {
+	tmpl, err := texttmpl.New(name).Option("missingkey=error").Parse(src)
+	if err != nil {
+		return "", err
+	}
+	var buf bytes.Buffer
+	if err := tmpl.Execute(&buf, data); err != nil {
+		return "", err
+	}
+	return strings.TrimSpace(buf.String()), nil
+}
+
+func renderOptionalTextTemplate(name, src string, data any) (string, error) {
+	if strings.TrimSpace(src) == "" {
+		return "", nil
+	}
+	return renderTextTemplate(name, src, data)
+}
+
+func renderOptionalHTMLTemplate(name, src string, data any) (string, error) {
+	if strings.TrimSpace(src) == "" {
+		return "", nil
+	}
+	tmpl, err := htmltmpl.New(name).Option("missingkey=error").Parse(src)
+	if err != nil {
+		return "", err
+	}
+	var buf bytes.Buffer
+	if err := tmpl.Execute(&buf, data); err != nil {
+		return "", err
+	}
+	return strings.TrimSpace(buf.String()), nil
+}

pkg/order/email_templates/fulfillment-shipped.json

@@ -0,0 +1,5 @@
+{
+  "subject": "Your order {{ .Order.OrderReference }} has shipped",
+  "text": "Hi {{ if .Order.CustomerName }}{{ .Order.CustomerName }}{{ else }}there{{ end }},\n\nYour order {{ .Order.OrderReference }} has shipped.\n{{ with .Fulfillment }}Carrier: {{ .Carrier }}\nTracking number: {{ .TrackingNumber }}\n{{ if .TrackingURI }}Track your shipment: {{ .TrackingURI }}\n{{ end }}{{ end }}\nOrder id: {{ .OrderID }}\n",
+  "html": "<p>Hi {{ if .Order.CustomerName }}{{ .Order.CustomerName }}{{ else }}there{{ end }},</p><p>Your order <strong>{{ .Order.OrderReference }}</strong> has shipped.</p>{{ with .Fulfillment }}<ul><li><strong>Carrier:</strong> {{ .Carrier }}</li><li><strong>Tracking number:</strong> {{ .TrackingNumber }}</li>{{ if .TrackingURI }}<li><a href=\"{{ .TrackingURI }}\">Track your shipment</a></li>{{ end }}</ul>{{ end }}<p>Order id: <code>{{ .OrderID }}</code></p>"
+}

pkg/order/emit_created.go

@@ -21,7 +21,7 @@ import (
 // retries delivery on its own. With a nil publisher (dev without AMQP) it is a
 // no-op. Attach it to the "after" hooks of the final paid step, e.g. capture.
 func RegisterOrderCreatedEmit(reg *flow.Registry, app Applier, pub Publisher, exchange, source string) {
-	reg.Hook("emit_order_created", func(ctx context.Context, st *flow.State, _ flow.HookInfo, _ json.RawMessage) error {
+	reg.HookWithMeta("emit_order_created", func(ctx context.Context, st *flow.State, _ flow.HookInfo, _ json.RawMessage) error {
 		if pub == nil {
 			return nil // no broker configured (dev)
 		}
@@ -51,19 +51,21 @@ func RegisterOrderCreatedEmit(reg *flow.Registry, app Applier, pub Publisher, ex
 			return err
 		}
 		return pub.Publish(exchange, string(event.OrderCreated), body)
+	}, flow.CapabilityMeta{
+		Description: "Emit the order.created domain event after a paid order is finalized.",
 	})
 }
 
 // buildOrderCreated projects the grain onto the exported order.created contract.
-// Lines carry only SKU + quantity (what reactors need); inventory commits at the
-// order's Country location.
+// Lines carry SKU, quantity, the inventory commit location, and the drop-ship
+// flag so the inventory reactor can skip the stock decrement for supplier-fulfilled items.
 func buildOrderCreated(o *OrderGrain) contract.Created {
 	lines := make([]contract.Line, 0, len(o.Lines))
 	for _, l := range o.Lines {
 		if l.Sku == "" || l.Quantity <= 0 {
 			continue
 		}
-		lines = append(lines, contract.Line{SKU: l.Sku, Quantity: l.Quantity, Location: l.Location})
+		lines = append(lines, contract.Line{SKU: l.Sku, Quantity: l.Quantity, Location: l.Location, DropShip: l.DropShip})
 	}
 	return contract.Created{
 		OrderID:        OrderId(o.Id).String(),

pkg/order/fulfillment_webhook.go

@@ -0,0 +1,109 @@
+package order
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"strings"
+	"time"
+
+	"git.k6n.net/mats/go-cart-actor/pkg/flow"
+)
+
+type fulfillmentWebhookParams struct {
+	URL         string            `json:"url"`
+	Method      string            `json:"method,omitempty"`
+	Headers     map[string]string `json:"headers,omitempty"`
+	ContentType string            `json:"contentType,omitempty"`
+}
+
+// RegisterFulfillmentWebhookHook registers the "fulfillment_webhook" flow hook.
+// It posts the current order + latest fulfillment to an external integration,
+// with templated URL/headers so flows can target dropship or ERP adapters
+// without custom Go code. Params:
+//
+//	{
+//	  "url": "https://example.test/hooks/{{ .OrderID }}",
+//	  "method": "POST",
+//	  "headers": {
+//	    "X-Integration": "dropship",
+//	    "Authorization": "Bearer {{ index .Vars \"token\" }}"
+//	  }
+//	}
+func RegisterFulfillmentWebhookHook(reg *flow.Registry, app Applier, client *http.Client) {
+	if client == nil {
+		client = &http.Client{Timeout: 10 * time.Second}
+	}
+	reg.HookWithMeta("fulfillment_webhook", func(ctx context.Context, st *flow.State, info flow.HookInfo, params json.RawMessage) error {
+		var p fulfillmentWebhookParams
+		if err := json.Unmarshal(params, &p); err != nil {
+			return fmt.Errorf("fulfillment_webhook: bad params: %w", err)
+		}
+		if strings.TrimSpace(p.URL) == "" {
+			return fmt.Errorf("fulfillment_webhook: missing url")
+		}
+		method := strings.ToUpper(strings.TrimSpace(p.Method))
+		if method == "" {
+			method = http.MethodPost
+		}
+		if p.ContentType == "" {
+			p.ContentType = "application/json"
+		}
+
+		o, err := app.Get(ctx, st.ID)
+		if err != nil {
+			return err
+		}
+		data := buildFlowTemplateData(o, st, info)
+		if data.Fulfillment == nil {
+			return fmt.Errorf("fulfillment_webhook: order %s has no fulfillment yet", data.OrderID)
+		}
+
+		url, err := renderTextTemplate("fulfillment-webhook-url", p.URL, data)
+		if err != nil {
+			return fmt.Errorf("fulfillment_webhook: render url: %w", err)
+		}
+
+		body, err := json.Marshal(map[string]any{
+			"orderId":         data.OrderID,
+			"step":            data.Step,
+			"phase":           data.Phase,
+			"error":           data.Error,
+			"order":           data.Order,
+			"fulfillment":     data.Fulfillment,
+			"billingAddress":  data.BillingAddress,
+			"shippingAddress": data.ShippingAddress,
+			"vars":            data.Vars,
+		})
+		if err != nil {
+			return fmt.Errorf("fulfillment_webhook: encode body: %w", err)
+		}
+
+		req, err := http.NewRequestWithContext(ctx, method, url, bytes.NewReader(body))
+		if err != nil {
+			return fmt.Errorf("fulfillment_webhook: build request: %w", err)
+		}
+		req.Header.Set("Content-Type", p.ContentType)
+		for key, raw := range p.Headers {
+			value, err := renderTextTemplate("fulfillment-webhook-header-"+key, raw, data)
+			if err != nil {
+				return fmt.Errorf("fulfillment_webhook: render header %s: %w", key, err)
+			}
+			req.Header.Set(key, value)
+		}
+		resp, err := client.Do(req)
+		if err != nil {
+			return fmt.Errorf("fulfillment_webhook: post %s: %w", url, err)
+		}
+		defer resp.Body.Close()
+		if resp.StatusCode >= 300 {
+			return fmt.Errorf("fulfillment_webhook: %s returned %d", url, resp.StatusCode)
+		}
+		return nil
+	}, flow.CapabilityMeta{
+		Description:   "POST the order and latest fulfillment to an external dropship or ERP endpoint.",
+		ExampleParams: json.RawMessage(`{"url":"https://dropship.example/hooks/{{ .OrderID }}","method":"POST","headers":{"X-Integration":"dropship {{ .Order.OrderReference }}","Authorization":"Bearer {{ index .Vars \"token\" }}"}}`),
+	})
+}

pkg/order/hooks.go

@@ -26,7 +26,7 @@ type Publisher interface {
 // still registered (so the editor lists it) but errors at run time — and since
 // hook errors never abort a flow, that failure is logged, not fatal.
 func RegisterEmitHook(reg *flow.Registry, pub Publisher) {
-	reg.Hook("amqp_emit", func(_ context.Context, st *flow.State, info flow.HookInfo, params json.RawMessage) error {
+	reg.HookWithMeta("amqp_emit", func(_ context.Context, st *flow.State, info flow.HookInfo, params json.RawMessage) error {
 		if pub == nil {
 			return fmt.Errorf("amqp_emit: no publisher configured")
 		}
@@ -54,5 +54,8 @@ func RegisterEmitHook(reg *flow.Registry, pub Publisher) {
 			"vars":  st.Vars,
 		})
 		return pub.Publish(p.Exchange, p.RoutingKey, body)
+	}, flow.CapabilityMeta{
+		Description:   "Publish the flow event payload to RabbitMQ.",
+		ExampleParams: json.RawMessage(`{"exchange":"order","routingKey":"order-events"}`),
 	})
 }

pkg/order/inventory_reservation.go

@@ -0,0 +1,179 @@
+package order
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"strings"
+	"time"
+
+	"git.k6n.net/mats/go-cart-actor/pkg/flow"
+)
+
+type InventoryReservationLine struct {
+	SKU        string `json:"sku"`
+	LocationID string `json:"locationId"`
+	Quantity   uint32 `json:"quantity"`
+}
+
+type InventoryReservationRequest struct {
+	HolderID string                     `json:"holderId"`
+	TTL      time.Duration              `json:"-"`
+	Lines    []InventoryReservationLine `json:"lines"`
+}
+
+type InventoryReservationService interface {
+	Reserve(ctx context.Context, req InventoryReservationRequest) error
+	Release(ctx context.Context, req InventoryReservationRequest) error
+}
+
+type HTTPInventoryReservationService struct {
+	baseURL string
+	client  *http.Client
+}
+
+func NewHTTPInventoryReservationService(baseURL string, client *http.Client) (*HTTPInventoryReservationService, error) {
+	baseURL = strings.TrimRight(strings.TrimSpace(baseURL), "/")
+	if baseURL == "" {
+		return nil, fmt.Errorf("inventory reservation service: missing base url")
+	}
+	if client == nil {
+		client = &http.Client{Timeout: 10 * time.Second}
+	}
+	return &HTTPInventoryReservationService{baseURL: baseURL, client: client}, nil
+}
+
+func (s *HTTPInventoryReservationService) Reserve(ctx context.Context, req InventoryReservationRequest) error {
+	return s.post(ctx, "/reservations", req)
+}
+
+func (s *HTTPInventoryReservationService) Release(ctx context.Context, req InventoryReservationRequest) error {
+	return s.post(ctx, "/reservations/release", req)
+}
+
+func (s *HTTPInventoryReservationService) post(ctx context.Context, path string, req InventoryReservationRequest) error {
+	body := map[string]any{
+		"holderId": req.HolderID,
+		"lines":    req.Lines,
+	}
+	if req.TTL > 0 {
+		body["ttlSeconds"] = int64(req.TTL / time.Second)
+	}
+	raw, err := json.Marshal(body)
+	if err != nil {
+		return err
+	}
+	httpReq, err := http.NewRequestWithContext(ctx, http.MethodPost, s.baseURL+path, bytes.NewReader(raw))
+	if err != nil {
+		return err
+	}
+	httpReq.Header.Set("Content-Type", "application/json")
+	resp, err := s.client.Do(httpReq)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode >= 300 {
+		return fmt.Errorf("inventory reservation service: %s returned %d", path, resp.StatusCode)
+	}
+	return nil
+}
+
+type reserveInventoryParams struct {
+	HolderID   string `json:"holderId,omitempty"`
+	TTLSeconds int64  `json:"ttlSeconds,omitempty"`
+	Lines      []struct {
+		Reference  string `json:"reference"`
+		Quantity   int32  `json:"quantity"`
+		LocationID string `json:"locationId,omitempty"`
+	} `json:"lines"`
+}
+
+func RegisterInventoryReservationActions(reg *flow.Registry, app Applier, svc InventoryReservationService) {
+	reg.ActionWithMeta("reserve_inventory", func(ctx context.Context, st *flow.State, params json.RawMessage) error {
+		if svc == nil {
+			return fmt.Errorf("reserve_inventory: no reservation service configured")
+		}
+		req, err := buildInventoryReservationRequest(ctx, app, st, params, "reserve_inventory")
+		if err != nil {
+			return err
+		}
+		return svc.Reserve(ctx, req)
+	}, flow.CapabilityMeta{
+		Description:   "Reserve inventory for specific order lines through the inventory service.",
+		ExampleParams: json.RawMessage(`{"ttlSeconds":900,"lines":[{"reference":"l1","quantity":1,"locationId":"se"}]}`),
+	})
+
+	reg.ActionWithMeta("release_inventory", func(ctx context.Context, st *flow.State, params json.RawMessage) error {
+		if svc == nil {
+			return fmt.Errorf("release_inventory: no reservation service configured")
+		}
+		req, err := buildInventoryReservationRequest(ctx, app, st, params, "release_inventory")
+		if err != nil {
+			return err
+		}
+		return svc.Release(ctx, req)
+	}, flow.CapabilityMeta{
+		Description:   "Release a prior inventory reservation for specific order lines.",
+		ExampleParams: json.RawMessage(`{"lines":[{"reference":"l1","quantity":1,"locationId":"se"}]}`),
+	})
+}
+
+func buildInventoryReservationRequest(ctx context.Context, app Applier, st *flow.State, params json.RawMessage, action string) (InventoryReservationRequest, error) {
+	var p reserveInventoryParams
+	if err := json.Unmarshal(params, &p); err != nil {
+		return InventoryReservationRequest{}, fmt.Errorf("%s: bad params: %w", action, err)
+	}
+	if len(p.Lines) == 0 {
+		return InventoryReservationRequest{}, fmt.Errorf("%s: missing lines", action)
+	}
+	o, err := app.Get(ctx, st.ID)
+	if err != nil {
+		return InventoryReservationRequest{}, err
+	}
+	holderID := p.HolderID
+	if holderID == "" {
+		holderID = "order:" + OrderId(st.ID).String()
+	}
+	req := InventoryReservationRequest{HolderID: holderID}
+	if p.TTLSeconds > 0 {
+		req.TTL = time.Duration(p.TTLSeconds) * time.Second
+	}
+	for _, lineReq := range p.Lines {
+		if lineReq.Reference == "" {
+			return InventoryReservationRequest{}, fmt.Errorf("%s: line missing reference", action)
+		}
+		if lineReq.Quantity <= 0 {
+			return InventoryReservationRequest{}, fmt.Errorf("%s: line %q has invalid quantity %d", action, lineReq.Reference, lineReq.Quantity)
+		}
+		line := o.findLine(lineReq.Reference)
+		if line == nil {
+			return InventoryReservationRequest{}, fmt.Errorf("%s: unknown line %q", action, lineReq.Reference)
+		}
+		if line.Sku == "" {
+			return InventoryReservationRequest{}, fmt.Errorf("%s: line %q has no sku", action, lineReq.Reference)
+		}
+		remaining := line.Quantity - line.Fulfilled
+		if int(lineReq.Quantity) > remaining {
+			return InventoryReservationRequest{}, fmt.Errorf("%s: line %q quantity %d exceeds remaining fulfillable %d", action, lineReq.Reference, lineReq.Quantity, remaining)
+		}
+		locationID := strings.TrimSpace(lineReq.LocationID)
+		if locationID == "" {
+			locationID = strings.TrimSpace(line.Location)
+		}
+		if locationID == "" {
+			locationID = strings.TrimSpace(o.Country)
+		}
+		if locationID == "" {
+			return InventoryReservationRequest{}, fmt.Errorf("%s: line %q has no location", action, lineReq.Reference)
+		}
+		req.Lines = append(req.Lines, InventoryReservationLine{
+			SKU:        line.Sku,
+			LocationID: locationID,
+			Quantity:   uint32(lineReq.Quantity),
+		})
+	}
+	return req, nil
+}

pkg/order/mutations.go

@@ -60,6 +60,7 @@ func HandlePlaceOrder(o *OrderGrain, m *messages.PlaceOrder) error {
 			TotalAmount: money.Cents(l.GetTotalAmount()),
 			TotalTax:    money.Cents(l.GetTotalTax()),
 			Location:    l.GetLocation(),
+			DropShip:    l.GetDropShip(),
 		})
 	}
 	o.Status = StatusPending

pkg/order/order-grain.go

@@ -66,6 +66,9 @@ type Line struct {
 	// Location is the inventory location / store id to commit against (empty =
 	// order country). Carried through to the order.created event for commit.
 	Location string `json:"location,omitempty"`
+	// DropShip marks items fulfilled by the supplier; the inventory reactor
+	// must skip the stock decrement. Set from the cart item at order creation.
+	DropShip bool `json:"drop_ship,omitempty"`
 	// Fulfilled tracks how many units of this line have shipped.
 	Fulfilled int `json:"fulfilled"`
 }

proto/order/order.pb.go

@@ -32,6 +32,7 @@ type OrderLine struct {
 	TotalAmount   int64                  `protobuf:"varint,7,opt,name=total_amount,json=totalAmount,proto3" json:"total_amount,omitempty"`
 	TotalTax      int64                  `protobuf:"varint,8,opt,name=total_tax,json=totalTax,proto3" json:"total_tax,omitempty"`
 	Location      string                 `protobuf:"bytes,9,opt,name=location,proto3" json:"location,omitempty"` // inventory location / store id for commit; empty = order country
+	DropShip      bool                   `protobuf:"varint,10,opt,name=drop_ship,json=dropShip,proto3" json:"drop_ship,omitempty"`
 	unknownFields protoimpl.UnknownFields
 	sizeCache     protoimpl.SizeCache
 }
@@ -129,6 +130,13 @@ func (x *OrderLine) GetLocation() string {
 	return ""
 }
 
+func (x *OrderLine) GetDropShip() bool {
+	if x != nil {
+		return x.DropShip
+	}
+	return false
+}
+
 // PlaceOrder creates the order (only legal when the order does not yet exist).
 type PlaceOrder struct {
 	state           protoimpl.MessageState `protogen:"open.v1"`