Fix Firebase Functions Emulator usage on Firebase Studio

.changeset/three-balloons-collect.md

@@ -0,0 +1,5 @@
+---
+"@firebase/functions": patch
+---
+
+Fixed issue where Firebase Functions SDK caused CORS errors when connected to emulators in Firebase Studio

packages/functions/src/callable.test.ts

@@ -523,8 +523,71 @@ describe('Firebase Functions > Stream', () => {
     const [_, options] = mockFetch.firstCall.args;
     expect(options.headers['Authorization']).to.equal('Bearer auth-token');
     expect(options.headers['Content-Type']).to.equal('application/json');
+    expect(options.credentials).to.equal(undefined);
     expect(options.headers['Accept']).to.equal('text/event-stream');
   });
+  it('calls cloud workstations with credentials', async () => {
+    const authMock: FirebaseAuthInternal = {
+      getToken: async () => ({ accessToken: 'auth-token' })
+    } as unknown as FirebaseAuthInternal;
+    const authProvider = new Provider<FirebaseAuthInternalName>(
+      'auth-internal',
+      new ComponentContainer('test')
+    );
+    authProvider.setComponent(
+      new Component('auth-internal', () => authMock, ComponentType.PRIVATE)
+    );
+    const appCheckMock: FirebaseAppCheckInternal = {
+      getToken: async () => ({ token: 'app-check-token' })
+    } as unknown as FirebaseAppCheckInternal;
+    const appCheckProvider = new Provider<AppCheckInternalComponentName>(
+      'app-check-internal',
+      new ComponentContainer('test')
+    );
+    appCheckProvider.setComponent(
+      new Component(
+        'app-check-internal',
+        () => appCheckMock,
+        ComponentType.PRIVATE
+      )
+    );
+
+    const functions = createTestService(
+      app,
+      region,
+      authProvider,
+      undefined,
+      appCheckProvider
+    );
+    functions.emulatorOrigin = 'test.cloudworkstations.dev';
+    const mockFetch = sinon.stub(functions, 'fetchImpl' as any);
+
+    const mockResponse = new ReadableStream({
+      start(controller) {
+        controller.enqueue(
+          new TextEncoder().encode('data: {"result":"Success"}\n')
+        );
+        controller.close();
+      }
+    });
+
+    mockFetch.resolves({
+      body: mockResponse,
+      headers: new Headers({ 'Content-Type': 'text/event-stream' }),
+      status: 200,
+      statusText: 'OK'
+    } as Response);
+
+    const func = httpsCallable<Record<string, any>, string, string>(
+      functions,
+      'stream'
+    );
+    await func.stream({});
+
+    expect(mockFetch.calledOnce).to.be.true;
+    const [_, options] = mockFetch.firstCall.args;
+    expect(options.credentials).to.equal('include');
+  });
 
   it('aborts during initial fetch', async () => {
     const controller = new AbortController();

packages/functions/src/service.ts

@@ -185,7 +185,7 @@ export function connectFunctionsEmulator(
   }://${host}:${port}`;
   // Workaround to get cookies in Firebase Studio
   if (useSsl) {
-    void pingServer(functionsInstance.emulatorOrigin);
+    void pingServer(functionsInstance.emulatorOrigin + '/backends');
     updateEmulatorBanner('Functions', true);
   }
 }
@@ -439,7 +439,12 @@ async function streamAtURL(
       method: 'POST',
       body: JSON.stringify(body),
       headers,
-      signal: options?.signal
+      signal: options?.signal,
+      credentials:
+        functionsInstance.emulatorOrigin &&
+        isCloudWorkstation(functionsInstance.emulatorOrigin)
+          ? 'include'
+          : undefined
     });
   } catch (e) {
     if (e instanceof Error && e.name === 'AbortError') {