mcp and ucp

cmd/checkout/main.go

@@ -10,6 +10,7 @@ import (
 	"os/signal"
 	"time"
 
+	"git.k6n.net/mats/go-cart-actor/internal/ucp"
 	"git.k6n.net/mats/go-cart-actor/pkg/actor"
 	"git.k6n.net/mats/go-cart-actor/pkg/checkout"
 	"git.k6n.net/mats/go-cart-actor/pkg/proxy"
@@ -48,6 +49,26 @@ var redisAddress = os.Getenv("REDIS_ADDRESS")
 var redisPassword = os.Getenv("REDIS_PASSWORD")
 var cartInternalUrl = os.Getenv("CART_INTERNAL_URL") // e.g., http://cart-service:8081
 
+// loadUCPCheckoutSigner 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 loadUCPCheckoutSigner() *ucp.SigningConfig {
+	path := os.Getenv("UCP_SIGNING_KEY_PATH")
+	if path == "" {
+		return nil
+	}
+	pemData, err := os.ReadFile(path)
+	if err != nil {
+		log.Printf("ucp signing: cannot read key %s: %v", path, err)
+		return nil
+	}
+	cfg, err := ucp.NewSigningConfigFromPEM(pemData, "k6n-ecdsa-2026")
+	if err != nil {
+		log.Printf("ucp signing: invalid key at %s: %v", path, err)
+		return nil
+	}
+	return cfg
+}
+
 func main() {
 
 	controlPlaneConfig := actor.DefaultServerConfig()
@@ -160,6 +181,22 @@ func main() {
 
 	syncedServer.Serve(mux)
 
+	// UCP REST adapter — Universal Commerce Protocol checkout sessions
+	// When an order service URL is configured, the complete endpoint creates
+	// real orders via the order service's from-checkout API.
+	var ucpOrderSvc ucp.OrderApplier
+	if orderServiceURL := os.Getenv("ORDER_SERVICE_URL"); orderServiceURL != "" {
+		ucpOrderSvc = ucp.NewOrderHTTPClient(orderServiceURL)
+		log.Printf("ucp order applier enabled: %s", orderServiceURL)
+	}
+	checkoutUCP := ucp.CheckoutHandler(pool, ucpOrderSvc)
+	if signer := loadUCPCheckoutSigner(); signer != nil {
+		checkoutUCP = ucp.WithSigning(checkoutUCP, signer)
+		log.Print("ucp signing enabled")
+	}
+	mux.Handle("/ucp/v1/checkout-sessions", checkoutUCP)
+	mux.Handle("/ucp/v1/checkout-sessions/", checkoutUCP)
+
 	mux.HandleFunc("/healthz", func(w http.ResponseWriter, r *http.Request) {
 		grainCount, capacity := pool.LocalUsage()
 		if grainCount >= capacity {