diff --git a/rest/nodejs/src/api/checkout.ts b/rest/nodejs/src/api/checkout.ts
index f8346e4..2447cd4 100644
--- a/rest/nodejs/src/api/checkout.ts
+++ b/rest/nodejs/src/api/checkout.ts
@@ -73,6 +73,37 @@ import { type IdParamContext } from "../utils/validation";
 /**
  * Service for managing checkout sessions.
  */
+// The order capability config of a platform types webhook_url as a string with
+// format uri (order.json, $defs/platform_schema), and notifyWebhook hands the
+// stored value to new URL() and fetch(). Only an http(s) URL without
+// credentials is a deliverable target, so anything else published in a profile
+// is dropped here with a log line, the way every other profile fault is
+// treated, instead of being stored, echoed on every response for the checkout,
+// and thrown on at delivery. The Python reference drops a malformed value the
+// same way; it keeps a URL carrying credentials, which its httpx client can
+// deliver to.
+function validWebhookUrl(value: unknown): string | undefined {
+  if (typeof value !== "string") {
+    return undefined;
+  }
+  try {
+    const target = new URL(value);
+    if (target.protocol !== "http:" && target.protocol !== "https:") {
+      return undefined;
+    }
+    // fetch() refuses to construct a request from a URL that carries
+    // credentials, so such a target can never receive a delivery either
+    // (the same check assertProfileUrlAllowed applies to a profile URL).
+    if (target.username || target.password) {
+      return undefined;
+    }
+    return value;
+  } catch {
+    // Not a URL at all; fall through to the drop below.
+  }
+  return undefined;
+}
+
 export class CheckoutService {
   private computeHash(
     operation: string,
@@ -147,7 +178,14 @@ export class CheckoutService {
         if (orderCaps && orderCaps.length > 0) {
           const orderCap = orderCaps[0];
           if (orderCap && orderCap.config && orderCap.config.webhook_url) {
-            return { webhook_url: orderCap.config.webhook_url };
+            const webhookUrl = validWebhookUrl(orderCap.config.webhook_url);
+            if (webhookUrl) {
+              return { webhook_url: webhookUrl };
+            }
+            console.warn(
+              "Ignoring malformed webhook_url in agent profile",
+              orderCap.config.webhook_url
+            );
           }
         }
       }
diff --git a/rest/nodejs/test/agent_profile.test.ts b/rest/nodejs/test/agent_profile.test.ts
new file mode 100644
index 0000000..4387686
--- /dev/null
+++ b/rest/nodejs/test/agent_profile.test.ts
@@ -0,0 +1,289 @@
+// Copyright 2026 UCP Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import assert from "node:assert/strict";
+import { before, test } from "node:test";
+
+import { zValidator } from "@hono/zod-validator";
+import { Hono } from "hono";
+
+import { CheckoutService } from "../src/api/checkout";
+import { getProductsDb, getTransactionsDb, initDbs } from "../src/data/db";
+import {
+  CheckoutCompleteRequestSchema,
+  ExtendedCheckoutCreateRequestSchema,
+  ExtendedCheckoutUpdateRequestSchema,
+} from "../src/models";
+import { IdParamSchema, prettyValidation } from "../src/utils/validation";
+
+// The order capability config of a platform carries the webhook URL the business
+// delivers order events to (order.md, Webhook URL Configuration). The schema
+// types it as a string with format uri (order.json, $defs/platform_schema),
+// and the delivery path hands the stored value to new URL() and fetch(). A
+// profile that publishes anything else must not be stored as the platform
+// webhook target: it would be echoed on every response for that checkout and
+// thrown on, or burned through retries, at delivery. This mirrors the
+// Python reference, which drops a malformed profile value with a log line.
+
+// A minimal app wired with just the checkout routes, the same convention as
+// lifecycle.test.ts, so the agent profile path is exercised through
+// app.request() with a real UCP-Agent header.
+function buildApp() {
+  const svc = new CheckoutService();
+  const app = new Hono<{ Variables: { logger: typeof console } }>();
+  app.use(async (c, next) => {
+    c.set("logger", console);
+    await next();
+  });
+  app.post(
+    "/checkout-sessions",
+    zValidator("json", ExtendedCheckoutCreateRequestSchema, prettyValidation),
+    svc.createCheckout
+  );
+  app.get(
+    "/checkout-sessions/:id",
+    zValidator("param", IdParamSchema, prettyValidation),
+    svc.getCheckout
+  );
+  app.put(
+    "/checkout-sessions/:id",
+    zValidator("param", IdParamSchema, prettyValidation),
+    zValidator("json", ExtendedCheckoutUpdateRequestSchema, prettyValidation),
+    svc.updateCheckout
+  );
+  app.post(
+    "/checkout-sessions/:id/complete",
+    zValidator("param", IdParamSchema, prettyValidation),
+    zValidator("json", CheckoutCompleteRequestSchema, prettyValidation),
+    svc.completeCheckout
+  );
+  return app;
+}
+
+before(() => {
+  initDbs(":memory:", ":memory:");
+  getProductsDb()
+    .prepare(
+      "INSERT INTO products (id, title, price, image_url) VALUES (?, ?, ?, ?)"
+    )
+    .run("bouquet_roses", "Red Rose", 3500, "");
+  getTransactionsDb()
+    .prepare("INSERT INTO inventory (product_id, quantity) VALUES (?, ?)")
+    .run("bouquet_roses", 100);
+});
+
+const VALID_WEBHOOK = "https://platform.example/ucp-webhook";
+const CREATE_BODY = {
+  currency: "USD",
+  line_items: [{ item: { id: "bouquet_roses" }, quantity: 1 }],
+  payment: {},
+  buyer: { email: "john.doe@example.com" },
+  fulfillment: {
+    methods: [{ type: "shipping", selected_destination_id: "addr_1" }],
+  },
+};
+
+// A platform profile whose order capability config carries `webhookUrl`,
+// delivered as a data: URI so the server parses it without any network.
+function agentHeader(webhookUrl: unknown): Record<string, string> {
+  const profile = {
+    ucp: {
+      version: "2026-04-08",
+      capabilities: {
+        "dev.ucp.shopping.order": [
+          {
+            name: "dev.ucp.shopping.order",
+            version: "2026-04-08",
+            config: { webhook_url: webhookUrl },
+          },
+        ],
+      },
+    },
+  };
+  const encoded = Buffer.from(JSON.stringify(profile)).toString("base64");
+  return {
+    "Content-Type": "application/json",
+    "UCP-Agent": `profile="data:application/json;base64,${encoded}"`,
+  };
+}
+
+async function create(app: ReturnType<typeof buildApp>, webhookUrl: unknown) {
+  const res = await app.request("/checkout-sessions", {
+    method: "POST",
+    headers: agentHeader(webhookUrl),
+    body: JSON.stringify(CREATE_BODY),
+  });
+  const text = await res.text();
+  assert.equal(res.status, 201, text);
+  return JSON.parse(text) as {
+    id: string;
+    platform?: { webhook_url?: unknown };
+    fulfillment: {
+      methods: {
+        groups: {
+          id: string;
+          line_item_ids: string[];
+          options: { id: string }[];
+        }[];
+      }[];
+    };
+  };
+}
+
+// Runs fn with console.warn captured, restoring it afterwards. The drop must
+// be loud: the log line is the only signal an operator gets that a platform
+// published a value the business cannot deliver to.
+async function captureWarnings<T>(
+  fn: () => Promise<T>
+): Promise<[T, unknown[][]]> {
+  const warned: unknown[][] = [];
+  const originalWarn = console.warn;
+  console.warn = (...args: unknown[]) => {
+    warned.push(args);
+  };
+  try {
+    return [await fn(), warned];
+  } finally {
+    console.warn = originalWarn;
+  }
+}
+
+test("a profile webhook_url that is a valid http(s) URL is stored and echoed", async () => {
+  const app = buildApp();
+  const created = await create(app, VALID_WEBHOOK);
+  assert.deepEqual(created.platform, { webhook_url: VALID_WEBHOOK });
+});
+
+for (const [label, value] of [
+  ["an ftp URL", "ftp://platform.invalid/hook"],
+  ["an integer", 42],
+  ["an object", { url: VALID_WEBHOOK }],
+  ["a data: URL", "data:text/plain,ok"],
+  ["a mailto: URL", "mailto:ops@platform.invalid"],
+  ["a string that is not a URL", "xts-not-a-url-2030"],
+  ["an array holding a valid URL", [VALID_WEBHOOK]],
+  ["a URL carrying credentials", "http://user:pass@platform.invalid/hook"],
+] as const) {
+  test(`a profile webhook_url that is ${label} is not stored or echoed`, async () => {
+    const app = buildApp();
+    const [created, warned] = await captureWarnings(() => create(app, value));
+    assert.equal(
+      created.platform,
+      undefined,
+      `platform must be absent, got ${JSON.stringify(created.platform)}`
+    );
+    assert.deepEqual(
+      warned.filter(
+        (args) => args[0] === "Ignoring malformed webhook_url in agent profile"
+      ),
+      [["Ignoring malformed webhook_url in agent profile", value]],
+      "the dropped value must be logged once"
+    );
+    const fetched = await app.request(`/checkout-sessions/${created.id}`);
+    assert.equal(fetched.status, 200);
+    const body = (await fetched.json()) as { platform?: unknown };
+    assert.equal(body.platform, undefined, "the value must not be persisted");
+  });
+}
+
+test("an update whose profile webhook_url is malformed keeps the stored valid one", async () => {
+  const app = buildApp();
+  const created = await create(app, VALID_WEBHOOK);
+  const res = await app.request(`/checkout-sessions/${created.id}`, {
+    method: "PUT",
+    headers: agentHeader("ftp://platform.invalid/hook"),
+    body: JSON.stringify({
+      currency: "USD",
+      line_items: [
+        { id: "line_1", item: { id: "bouquet_roses" }, quantity: 1 },
+      ],
+      buyer: { email: "john.doe@example.com" },
+    }),
+  });
+  const text = await res.text();
+  assert.equal(res.status, 200, text);
+  const body = JSON.parse(text) as { platform?: { webhook_url?: unknown } };
+  assert.deepEqual(body.platform, { webhook_url: VALID_WEBHOOK });
+});
+
+test("completing a checkout whose profile webhook_url is malformed attempts no delivery", async () => {
+  const app = buildApp();
+  const created = await create(app, "ftp://platform.invalid/hook");
+  const group = created.fulfillment.methods[0]!.groups[0]!;
+  const selected = await app.request(`/checkout-sessions/${created.id}`, {
+    method: "PUT",
+    headers: agentHeader("ftp://platform.invalid/hook"),
+    body: JSON.stringify({
+      currency: "USD",
+      line_items: [
+        { id: "line_1", item: { id: "bouquet_roses" }, quantity: 1 },
+      ],
+      buyer: { email: "john.doe@example.com" },
+      fulfillment: {
+        methods: [
+          {
+            type: "shipping",
+            selected_destination_id: "addr_1",
+            groups: [
+              {
+                id: group.id,
+                line_item_ids: group.line_item_ids,
+                selected_option_id: group.options[0]!.id,
+              },
+            ],
+          },
+        ],
+      },
+    }),
+  });
+  assert.equal(selected.status, 200, await selected.clone().text());
+
+  const attempted: string[] = [];
+  const originalFetch = globalThis.fetch;
+  globalThis.fetch = (async (url: string | URL | Request) => {
+    attempted.push(String(url));
+    return new Response(null, { status: 200 });
+  }) as typeof globalThis.fetch;
+  try {
+    const res = await app.request(`/checkout-sessions/${created.id}/complete`, {
+      method: "POST",
+      headers: agentHeader("ftp://platform.invalid/hook"),
+      body: JSON.stringify({
+        payment: {
+          instruments: [
+            {
+              id: "pi_1",
+              handler_id: "mock_payment_handler",
+              type: "card",
+              brand: "visa",
+              last_digits: "4242",
+              credential: { type: "network_token", token: "success_token" },
+            },
+          ],
+        },
+      }),
+    });
+    const text = await res.text();
+    assert.equal(res.status, 200, text);
+    const body = JSON.parse(text) as { status: string };
+    assert.equal(body.status, "completed");
+  } finally {
+    globalThis.fetch = originalFetch;
+  }
+  assert.deepEqual(
+    attempted,
+    [],
+    "no webhook delivery may be attempted to a target that is not a URL"
+  );
+});