Extend /api/health with ?deep=1 mode that verifies: BUILD_ID matches .next on disk, tasks/ readable, gateway reachable, data/ parseable. Layer 3 self-test uses deep mode for stronger guarantees.

Implementation#

3 files changed:

• app/api/health/route.ts — added deep probe (build_id, tasks_dir, gateway, data_dir checks) when ?deep=1 is passed
• __tests__/api-health-route.test.ts — 13 tests covering shallow + deep mode
• start.sh — Layer 3 self-test now polls /api/health?deep=1 instead of /api/health
• __tests__/start-sh-selftest.test.ts — updated test to check for ?deep=1 URL

Verification#

• tsc --noEmit: zero new type errors
• 13/13 tests pass (api-health-route)
• 7/7 tests pass (start-sh-selftest)