diff --git a/tests/smoke/icon.test.ts b/tests/smoke/icon.test.ts
index 01965629..37b93a8d 100644
--- a/tests/smoke/icon.test.ts
+++ b/tests/smoke/icon.test.ts
@@ -1,3 +1,4 @@
+// @vitest-environment node
 import { describe, it, expect } from "vitest";
 
 /**
@@ -14,20 +15,22 @@ const BASE = process.env.SMOKE_BASE_URL ?? "https://my.feedzero.app";
 const enabled = process.env.SMOKE_TESTS === "1";
 
 describe.skipIf(!enabled)("smoke: /api/icon", () => {
+  // Fixtures are our own domain: example.com has no favicon at all (its
+  // ?domain= answer is an empty text/plain 200, its /favicon.ico a 404),
+  // which is exactly the "mock encodes a belief about the service" trap
+  // CLAUDE.md's Tier 2.5 rule warns about. Verified with curl before use.
   it("serves a favicon for ?domain= with a cacheable image response", async () => {
-    const res = await fetch(`${BASE}/api/icon?domain=example.com`);
+    const res = await fetch(`${BASE}/api/icon?domain=feedzero.app`);
     expect(res.status).toBe(200);
     expect(res.headers.get("content-type")).toMatch(/^image\//);
     expect(res.headers.get("cache-control")).toMatch(/max-age=86400/);
   });
 
-  it("proxies an explicit image url", async () => {
+  it("proxies an explicit image url as an image", async () => {
     const res = await fetch(
-      `${BASE}/api/icon?url=${encodeURIComponent("https://example.com/favicon.ico")}`,
+      `${BASE}/api/icon?url=${encodeURIComponent("https://feedzero.app/favicon.ico")}`,
     );
-    // example.com has no favicon; the contract is that the proxy answers
-    // for the URL rather than rejecting the shape.
-    expect([200, 404, 502]).toContain(res.status);
-    expect(res.status).not.toBe(400);
+    expect(res.status).toBe(200);
+    expect(res.headers.get("content-type")).toMatch(/^image\//);
   });
 });