fix(nodejs): derive discovery endpoint from request origin

rest/nodejs/src/api/discovery.ts

@@ -110,7 +110,7 @@ export class DiscoveryService {
             spec: `https://ucp.dev/${this.ucpVersion}/specification/shopping`,
             transport: "rest",
             schema: `https://ucp.dev/${this.ucpVersion}/services/shopping/openapi.json`,
-            endpoint: "http://localhost:3000",
+            endpoint: new URL(c.req.url).origin,
           },
         ],
       },

rest/nodejs/test/discovery.test.ts

@@ -26,7 +26,7 @@ test("merchant profile uses schema-compliant discovery registries", async () =>
   assert.ok(Array.isArray(shoppingServices));
   assert.equal(shoppingServices.length, 1);
   assert.equal(shoppingServices[0]?.transport, "rest");
-  assert.equal(shoppingServices[0]?.endpoint, "http://localhost:3000");
+  assert.equal(shoppingServices[0]?.endpoint, "http://localhost");
 
   assert.equal(Array.isArray(body.ucp.capabilities), false);
   assert.deepEqual(Object.keys(body.ucp.capabilities).sort(), [
@@ -46,3 +46,20 @@ test("merchant profile uses schema-compliant discovery registries", async () =>
     assert.equal(declarations[0]?.version, discoveryService.ucpVersion);
   }
 });
+
+test("merchant profile derives the REST endpoint from the request origin", async () => {
+  const app = new Hono();
+  const discoveryService = new DiscoveryService();
+  app.get("/.well-known/ucp", discoveryService.getMerchantProfile);
+
+  const response = await app.request(
+    "https://merchant.example:8443/.well-known/ucp"
+  );
+  const body = (await response.json()) as DiscoveryResponse;
+
+  assert.equal(response.status, 200);
+  assert.equal(
+    body.ucp.services["dev.ucp.shopping"]?.[0]?.endpoint,
+    "https://merchant.example:8443"
+  );
+});