fix: robust test fix + CI serialization for integration tests

- Frontend: Clear setQueryData spy after mutateAsync so the assertion
  only catches the poll's call, not any optimistic onMutate update.

- CI: Add --no-file-parallelism to Backend CI and pr-test-gate
  workflows instead of baking it into vitest.config.ts so local
  devs can still run fast parallel tests.

Author: Hollujay

.github/workflows/ci.yml

@@ -96,7 +96,7 @@ jobs:
       - name: Run Backend Tests
         run: |
           ls -la src/generated/prisma
-          npx vitest run --coverage --reporter=basic
+          npx vitest run --coverage --reporter=basic --no-file-parallelism
         working-directory: backend
         env:
           DATABASE_URL: postgresql://postgres:password@127.0.0.1:5432/flowfi_test

.github/workflows/pr-test-gate.yml

@@ -65,7 +65,7 @@ jobs:
           DATABASE_URL: postgresql://postgres:password@127.0.0.1:5432/flowfi_test
 
       - name: Run backend tests
-        run: npm test
+        run: npm test -- --no-file-parallelism
         working-directory: backend
         env:
           DATABASE_URL: postgresql://postgres:password@127.0.0.1:5432/flowfi_test

backend/vitest.config.ts

@@ -43,8 +43,5 @@ export default defineConfig({
         // Run each test file in its own forked process so vi.mock() doesn't leak
         pool: 'forks',
         isolate: true,
-        // Run files sequentially so integration tests sharing the same DB
-        // don't clobber each other's cleanup (foreign key violations).
-        fileParallelism: false,
     },
 });

frontend/src/hooks/useIncomingStreams.test.tsx

@@ -111,6 +111,10 @@ describe("useIncomingStreams hooks", () => {
         } as any);
       });
 
+      // Clear any calls made during mutation (e.g. optimistic update in
+      // onMutate) so we only assert on the poll's setQueryData call.
+      setQueryDataSpy.mockClear();
+
       // Poll should find the updated stream (withdrawn 100 > 0) and call
       // setQueryData after ~1 s of simulated delay.
       await waitFor(() => {