CI: run dev tests single-worker (#1153)

Runs dev-focused CI test suites with a single Vitest worker to reduce
load and avoid external DB sync timeouts.

.github/workflows/e2e-api-tests.yaml

@@ -175,16 +175,27 @@ jobs:
             sleep 2
           done
 
-      - name: Run tests
-        run: pnpm test run ${{ matrix.freestyle-mode == 'prod' && '--min-workers=1 --max-workers=1' || '' }}
+      - name: Run tests (excluding external DB sync)
+        run: pnpm test run ${{ matrix.freestyle-mode == 'prod' && '--min-workers=1 --max-workers=1' || '' }} --exclude "**/external-db-sync*.test.ts"
 
-      - name: Run tests again, to make sure they are stable (attempt 1)
-        if: github.ref == 'refs/heads/main' || github.ref == 'refs/heads/dev'
-        run: pnpm test run ${{ matrix.freestyle-mode == 'prod' && '--min-workers=1 --max-workers=1' || '' }}
+      - name: Run external DB sync tests (single worker)
+        run: pnpm test run --min-workers=1 --max-workers=1 **/external-db-sync*.test.ts
 
-      - name: Run tests again, to make sure they are stable (attempt 2)
+      - name: Run tests again (excluding external DB sync, attempt 1)
         if: github.ref == 'refs/heads/main' || github.ref == 'refs/heads/dev'
-        run: pnpm test run ${{ matrix.freestyle-mode == 'prod' && '--min-workers=1 --max-workers=1' || '' }}
+        run: pnpm test run ${{ matrix.freestyle-mode == 'prod' && '--min-workers=1 --max-workers=1' || '' }} --exclude "**/external-db-sync*.test.ts"
+
+      - name: Run external DB sync tests again (single worker, attempt 1)
+        if: github.ref == 'refs/heads/main' || github.ref == 'refs/heads/dev'
+        run: pnpm test run --min-workers=1 --max-workers=1 **/external-db-sync*.test.ts
+
+      - name: Run tests again (excluding external DB sync, attempt 2)
+        if: github.ref == 'refs/heads/main' || github.ref == 'refs/heads/dev'
+        run: pnpm test run ${{ matrix.freestyle-mode == 'prod' && '--min-workers=1 --max-workers=1' || '' }} --exclude "**/external-db-sync*.test.ts"
+
+      - name: Run external DB sync tests again (single worker, attempt 2)
+        if: github.ref == 'refs/heads/main' || github.ref == 'refs/heads/dev'
+        run: pnpm test run --min-workers=1 --max-workers=1 **/external-db-sync*.test.ts
 
       - name: Verify data integrity
         run: pnpm run verify-data-integrity --no-bail

.github/workflows/e2e-custom-base-port-api-tests.yaml

@@ -168,16 +168,27 @@ jobs:
             sleep 2
           done
 
-      - name: Run tests
-        run: pnpm test run
+      - name: Run tests (excluding external DB sync)
+        run: pnpm test run --exclude "**/external-db-sync*.test.ts"
 
-      - name: Run tests again, to make sure they are stable (attempt 1)
-        if: github.ref == 'refs/heads/main' || github.ref == 'refs/heads/dev'
-        run: pnpm test run
+      - name: Run external DB sync tests (single worker)
+        run: pnpm test run --min-workers=1 --max-workers=1 **/external-db-sync*.test.ts
 
-      - name: Run tests again, to make sure they are stable (attempt 2)
+      - name: Run tests again (excluding external DB sync, attempt 1)
         if: github.ref == 'refs/heads/main' || github.ref == 'refs/heads/dev'
-        run: pnpm test run
+        run: pnpm test run --exclude "**/external-db-sync*.test.ts"
+
+      - name: Run external DB sync tests again (single worker, attempt 1)
+        if: github.ref == 'refs/heads/main' || github.ref == 'refs/heads/dev'
+        run: pnpm test run --min-workers=1 --max-workers=1 **/external-db-sync*.test.ts
+
+      - name: Run tests again (excluding external DB sync, attempt 2)
+        if: github.ref == 'refs/heads/main' || github.ref == 'refs/heads/dev'
+        run: pnpm test run --exclude "**/external-db-sync*.test.ts"
+
+      - name: Run external DB sync tests again (single worker, attempt 2)
+        if: github.ref == 'refs/heads/main' || github.ref == 'refs/heads/dev'
+        run: pnpm test run --min-workers=1 --max-workers=1 **/external-db-sync*.test.ts
 
       - name: Verify data integrity
         run: pnpm run verify-data-integrity --no-bail

.github/workflows/e2e-source-of-truth-api-tests.yaml

@@ -175,16 +175,27 @@ jobs:
             sleep 2
           done
 
-      - name: Run tests
-        run: pnpm test run
+      - name: Run tests (excluding external DB sync)
+        run: pnpm test run --exclude "**/external-db-sync*.test.ts"
 
-      - name: Run tests again, to make sure they are stable (attempt 1)
-        if: github.ref == 'refs/heads/main' || github.ref == 'refs/heads/dev'
-        run: pnpm test run
+      - name: Run external DB sync tests (single worker)
+        run: pnpm test run --min-workers=1 --max-workers=1 **/external-db-sync*.test.ts
 
-      - name: Run tests again, to make sure they are stable (attempt 2)
+      - name: Run tests again (excluding external DB sync, attempt 1)
         if: github.ref == 'refs/heads/main' || github.ref == 'refs/heads/dev'
-        run: pnpm test run
+        run: pnpm test run --exclude "**/external-db-sync*.test.ts"
+
+      - name: Run external DB sync tests again (single worker, attempt 1)
+        if: github.ref == 'refs/heads/main' || github.ref == 'refs/heads/dev'
+        run: pnpm test run --min-workers=1 --max-workers=1 **/external-db-sync*.test.ts
+
+      - name: Run tests again (excluding external DB sync, attempt 2)
+        if: github.ref == 'refs/heads/main' || github.ref == 'refs/heads/dev'
+        run: pnpm test run --exclude "**/external-db-sync*.test.ts"
+
+      - name: Run external DB sync tests again (single worker, attempt 2)
+        if: github.ref == 'refs/heads/main' || github.ref == 'refs/heads/dev'
+        run: pnpm test run --min-workers=1 --max-workers=1 **/external-db-sync*.test.ts
 
       - name: Verify data integrity
         run: pnpm run verify-data-integrity --no-bail

.github/workflows/restart-dev-and-test-with-custom-base-port.yaml

@@ -40,8 +40,11 @@ jobs:
       - name: Start dev environment
         run: pnpm run restart-dev-environment
 
-      - name: Run tests
-        run: pnpm run test run --reporter=verbose
+      - name: Run tests (excluding external DB sync)
+        run: pnpm run test run --reporter=verbose --exclude "**/external-db-sync*.test.ts"
+
+      - name: Run external DB sync tests (single worker)
+        run: pnpm run test run --reporter=verbose --min-workers=1 --max-workers=1 **/external-db-sync*.test.ts
       
       - name: Print dev server logs
         run: cat dev-server.log.untracked.txt

.github/workflows/restart-dev-and-test.yaml

@@ -39,8 +39,11 @@ jobs:
       - name: Start dev environment
         run: pnpm run restart-dev-environment
 
-      - name: Run tests
-        run: pnpm run test run --reporter=verbose
+      - name: Run tests (excluding external DB sync)
+        run: pnpm run test run --reporter=verbose --exclude "**/external-db-sync*.test.ts"
+
+      - name: Run external DB sync tests (single worker)
+        run: pnpm run test run --reporter=verbose --min-workers=1 --max-workers=1 **/external-db-sync*.test.ts
       
       - name: Print dev server logs
         run: cat dev-server.log.untracked.txt

.github/workflows/setup-tests-with-custom-base-port.yaml

@@ -49,4 +49,8 @@ jobs:
           tail: true
           wait-for: 120s
           log-output-if: true
-      - run: pnpm run test run --reporter=verbose
+      - name: Run tests (excluding external DB sync)
+        run: pnpm run test run --reporter=verbose --exclude "**/external-db-sync*.test.ts"
+
+      - name: Run external DB sync tests (single worker)
+        run: pnpm run test run --reporter=verbose --min-workers=1 --max-workers=1 **/external-db-sync*.test.ts

.github/workflows/setup-tests.yaml

@@ -47,4 +47,8 @@ jobs:
           tail: true
           wait-for: 120s
           log-output-if: true
-      - run: pnpm run test run --reporter=verbose
+      - name: Run tests (excluding external DB sync)
+        run: pnpm run test run --reporter=verbose --exclude "**/external-db-sync*.test.ts"
+
+      - name: Run external DB sync tests (single worker)
+        run: pnpm run test run --reporter=verbose --min-workers=1 --max-workers=1 **/external-db-sync*.test.ts

claude/CLAUDE-KNOWLEDGE.md

@@ -8,3 +8,12 @@ A: Use the shared `TextAreaField` component's `helperText` prop in `apps/dashboa
 
 Q: Why did `pnpm typecheck` fail after deleting a Next.js route?
 A: The generated `.next/types/validator.ts` can keep stale imports for removed routes. Deleting that file (or regenerating Next build output) clears the outdated references so `pnpm typecheck` succeeds again.
+
+Q: Why can external DB sync tests time out in dev-focused GitHub workflows?
+A: The first calls to `/api/latest/internal/external-db-sync/sequencer` and `/poller` can be slow in dev mode and hit Undici's headers timeout; prewarming those endpoints with the cron secret, retrying header-timeout failures in the test helper, or running tests single-worker are viable mitigations.
+
+Q: How can we serialize only the external DB sync Vitest files while keeping the rest parallel?
+A: Use `poolMatchGlobs` to route the external DB sync test globs to the `forks` pool and set `poolOptions.forks.{minForks,maxForks}=1` in `apps/e2e/vitest.config.ts`; keep the default threads pool for all other tests.
+
+Q: How can CI keep most tests parallel while isolating external DB sync tests?
+A: Split workflow test runs into two steps: run the full suite with `--exclude "**/external-db-sync*.test.ts"`, then run only external DB sync tests with `--min-workers=1 --max-workers=1`.