fix: health endpoint crashes when Supabase env vars are missing (#36)

[zacharias-ona]

Closes #36

What

The health endpoint (GET /api/health) reported {"status":"down","db":{"connected":false,"latency_ms":0}} when Supabase environment variables were not configured in Vercel. The route handler called createClient() without checking whether NEXT_PUBLIC_SUPABASE_URL and NEXT_PUBLIC_SUPABASE_PUBLISHABLE_KEY were set. The non-null assertions (!) silently passed undefined to createServerClient, which threw when making the HTTP request. The catch block then reported the database as "down" — misleading, since the database was never reached.

How

Added an env var guard at the top of the health route handler, matching the pattern already used in src/proxy.ts. When Supabase env vars are missing, the endpoint returns {"status":"ok","db":{"connected":false,"latency_ms":0,"reason":"not_configured"}} instead of crashing into the catch block. The overall app status remains "ok" since the app itself is running — only the DB connection is absent.

Also updated .agents/conventions.md with the env var guard pattern (placed next to the API routes section) to prevent the same class of bug in future route handlers.

Testing

Added 6 regression tests in src/app/api/health/route.test.ts:

• Missing both env vars → returns not_configured (would have caught this bug)
• Missing only URL → returns not_configured
• Table does not exist → returns ok/connected (connection worked)
• Successful query → returns ok/connected
• Non-connection error (e.g., permission denied) → returns degraded
• Client throws (e.g., fetch failed) → returns down

Run: pnpm test -- src/app/api/health/route.test.ts

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Project	Deployment	Actions	Updated (UTC)
memo	Ready	Preview, Comment	Apr 15, 2026 10:00am

[zacharias-ona]

Closing as duplicate. The identical fix was already merged via PR #40 (commit 8e30ff2 on main, merged 2026-04-15T10:00:32Z). This PR has merge conflicts because the same changes already exist on main.

[zacharias-ona]

Review — no blocking issues found.

• Correctness: Env var guard prevents createClient() from receiving undefined, returns status: ok with reason: not_configured — appropriate since the app is running, only DB is absent.
• Tests: 6 tests cover all branches (missing env vars, partial, table-not-found, success, degraded, client throw). Assertions match the route handler.
• Conventions: Follows the proxy pattern, strict TypeScript, named export, no suppressions.
• Scope: Limited to health route, its tests, and conventions docs.

[zacharias-ona]

Closing in favor of #43, which applies the same changes rebased cleanly onto current main. This PR had unresolvable merge conflicts due to overlapping changes from #40 already on main.