mcp and ucp

cmd/cart/main.go

@@ -16,6 +16,7 @@ import (
 	"git.k6n.net/mats/go-cart-actor/pkg/cart"
 	"git.k6n.net/mats/go-cart-actor/pkg/promotions"
 	promotionmcp "git.k6n.net/mats/go-cart-actor/pkg/promotions/mcp"
+	"git.k6n.net/mats/go-cart-actor/internal/ucp"
 	"git.k6n.net/mats/go-cart-actor/pkg/proxy"
 	"git.k6n.net/mats/go-cart-actor/pkg/voucher"
 	"git.k6n.net/mats/go-redis-inventory/pkg/inventory"
@@ -66,6 +67,26 @@ func normalizeListenAddr(v string) string {
 	return ":" + v
 }
 
+// loadUCPCartSigner 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 loadUCPCartSigner() *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 getCountryFromHost(host string) string {
 	if strings.Contains(strings.ToLower(host), "-no") {
 		return "no"
@@ -278,6 +299,15 @@ func main() {
 	mux.Handle("/mcp", promotionMCP.Handler())
 	mux.Handle("/mcp/", promotionMCP.Handler())
 
+	// UCP REST adapter — Universal Commerce Protocol
+	cartUCP := ucp.CartHandler(pool)
+	if signer := loadUCPCartSigner(); signer != nil {
+		cartUCP = ucp.WithSigning(cartUCP, signer)
+		log.Print("ucp signing enabled")
+	}
+	mux.Handle("/ucp/v1/carts", cartUCP)
+	mux.Handle("/ucp/v1/carts/", cartUCP)
+
 	// Stateless promotion evaluation: POST a (possibly partial) eval context and
 	// get back the resulting totals plus the applied/pending effect breakdown,
 	// without creating or mutating a real cart.