diff --git a/extensions/msteams/src/graph-upload.test.ts b/extensions/msteams/src/graph-upload.test.ts
index 484075984dd..b79086f54ca 100644
--- a/extensions/msteams/src/graph-upload.test.ts
+++ b/extensions/msteams/src/graph-upload.test.ts
@@ -1,4 +1,5 @@
 import { describe, expect, it, vi } from "vitest";
+import { withFetchPreconnect } from "../../../src/test-utils/fetch-mock.js";
 import { uploadToOneDrive, uploadToSharePoint } from "./graph-upload.js";
 
 describe("graph upload helpers", () => {
@@ -22,7 +23,7 @@ describe("graph upload helpers", () => {
       buffer: Buffer.from("hello"),
       filename: "a.txt",
       tokenProvider,
-      fetchFn: fetchFn as typeof fetch,
+      fetchFn: withFetchPreconnect(fetchFn),
     });
 
     expect(fetchFn).toHaveBeenCalledWith(
@@ -59,7 +60,7 @@ describe("graph upload helpers", () => {
       filename: "b.txt",
       siteId: "site-123",
       tokenProvider,
-      fetchFn: fetchFn as typeof fetch,
+      fetchFn: withFetchPreconnect(fetchFn),
     });
 
     expect(fetchFn).toHaveBeenCalledWith(
@@ -94,7 +95,7 @@ describe("graph upload helpers", () => {
         filename: "bad.txt",
         siteId: "site-123",
         tokenProvider,
-        fetchFn: fetchFn as typeof fetch,
+        fetchFn: withFetchPreconnect(fetchFn),
       }),
     ).rejects.toThrow("SharePoint upload response missing required fields");
   });
diff --git a/src/agents/model-auth.test.ts b/src/agents/model-auth.test.ts
index de8f0f1b752..31fdee5496c 100644
--- a/src/agents/model-auth.test.ts
+++ b/src/agents/model-auth.test.ts
@@ -1,5 +1,6 @@
 import { streamSimpleOpenAICompletions, type Model } from "@mariozechner/pi-ai";
 import { afterEach, describe, expect, it, vi } from "vitest";
+import { withFetchPreconnect } from "../test-utils/fetch-mock.js";
 import type { AuthProfileStore } from "./auth-profiles.js";
 import { CUSTOM_LOCAL_AUTH_MARKER, NON_ENV_SECRETREF_MARKER } from "./model-auth-markers.js";
 import {
@@ -503,16 +504,18 @@ describe("applyLocalNoAuthHeaderOverride", () => {
     const requestSeen = new Promise<void>((resolve) => {
       resolveRequest = resolve;
     });
-    globalThis.fetch = vi.fn(async (_input, init) => {
-      const headers = new Headers(init?.headers);
-      capturedAuthorization = headers.get("Authorization");
-      capturedXTest = headers.get("X-Test");
-      resolveRequest?.();
-      return new Response(JSON.stringify({ error: { message: "unauthorized" } }), {
-        status: 401,
-        headers: { "content-type": "application/json" },
-      });
-    }) as typeof fetch;
+    globalThis.fetch = withFetchPreconnect(
+      vi.fn(async (_input, init) => {
+        const headers = new Headers(init?.headers);
+        capturedAuthorization = headers.get("Authorization");
+        capturedXTest = headers.get("X-Test");
+        resolveRequest?.();
+        return new Response(JSON.stringify({ error: { message: "unauthorized" } }), {
+          status: 401,
+          headers: { "content-type": "application/json" },
+        });
+      }),
+    );
 
     const model = applyLocalNoAuthHeaderOverride(
       {
diff --git a/src/infra/fetch.test.ts b/src/infra/fetch.test.ts
index deef81f551f..820325c0e70 100644
--- a/src/infra/fetch.test.ts
+++ b/src/infra/fetch.test.ts
@@ -293,7 +293,7 @@ describe("wrapFetchWithAbortSignal", () => {
   });
 
   it("exposes a no-op preconnect when the source fetch has none", () => {
-    const fetchImpl = vi.fn(async () => ({ ok: true }) as Response) as typeof fetch;
+    const fetchImpl = withFetchPreconnect(vi.fn(async () => ({ ok: true }) as Response));
     const wrapped = wrapFetchWithAbortSignal(fetchImpl) as typeof fetch & {
       preconnect: (url: string, init?: { credentials?: RequestCredentials }) => unknown;
     };
diff --git a/src/infra/provider-usage.fetch.shared.test.ts b/src/infra/provider-usage.fetch.shared.test.ts
index 692a57705db..b287f1fad04 100644
--- a/src/infra/provider-usage.fetch.shared.test.ts
+++ b/src/infra/provider-usage.fetch.shared.test.ts
@@ -1,4 +1,5 @@
 import { afterEach, describe, expect, it, vi } from "vitest";
+import { withFetchPreconnect } from "../test-utils/fetch-mock.js";
 import {
   buildUsageErrorSnapshot,
   buildUsageHttpErrorSnapshot,
@@ -36,7 +37,7 @@ describe("provider usage fetch shared helpers", () => {
       async (_input: URL | RequestInfo, init?: RequestInit) =>
         new Response(JSON.stringify({ aborted: init?.signal?.aborted ?? false }), { status: 200 }),
     );
-    const fetchFn = fetchFnMock as typeof fetch;
+    const fetchFn = withFetchPreconnect(fetchFnMock);
 
     const response = await fetchJson(
       "https://example.com/usage",
@@ -71,7 +72,7 @@ describe("provider usage fetch shared helpers", () => {
           });
         }),
     );
-    const fetchFn = fetchFnMock as typeof fetch;
+    const fetchFn = withFetchPreconnect(fetchFnMock);
 
     const request = fetchJson("https://example.com/usage", {}, 50, fetchFn);
     const rejection = expect(request).rejects.toThrow("aborted by timeout");