The integration suite runs with `vitest isolate: false` (one worker,
one container — migration cost demands it). Each test file declared
its own `vi.mock("next/headers", ...)` whose factory closed over a
file-local `cookieJar` Map. Vitest resolves a mock factory ONCE per
worker — whichever file loaded first won the registration, and the
other files' Map writes silently disappeared.
That made `admin-data-wipe.test.ts` flake intermittently (~12.5% per
empirical 8-run sample) when `idempotency-replay.test.ts` happened to
load first: its `vi.mock("@/lib/auth/session", ...)` then leaked,
returning a stub user without an admin role, so `requireAdmin()`
returned 401 and the wipe assertion failed with `expected 401 to be
200`.
Fix: extract cookieJar + headerJar into module-singleton Maps in
`tests/integration/mock-next-headers.ts`. All three integration files
import them and resolve them via dynamic-import inside the
`vi.mock("next/headers", ...)` factory body, so the factory always
sees the same backing Maps regardless of which file's registration
won the race. The `vi.mock("@/lib/auth/session", ...)` stub in
idempotency-replay was also removed; the test now seeds a real
Session row + cookie like the other two files.
After: 10/10 consecutive `pnpm test:integration` runs green.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
