Graceful Shutdown

Mishandling of Exceptional Conditions. Shutdown behavior and data safety for all background systems.

Systems

1. Trigger.dev (Background Jobs)

Shutdown: SDK registers SIGTERM + SIGINT automatically. When Vercel sends SIGTERM:

1. Stops accepting new jobs
2. In-progress jobs get grace period to complete
3. Unfinished jobs marked for retry

Data Safety:

• Idempotent by design — safe to retry
• State in Trigger.dev cloud, not in-process
• Failed jobs auto-retry with exponential backoff

Risk: Minimal. Managed infrastructure handles this.

2. QStash (Delayed Messages / Webhooks)

Shutdown: Fully HTTP-based. No persistent connections. No in-process state.

1. QStash sends HTTP POST
2. Endpoint processes → response
3. Unavailable = QStash retries automatically

Data Safety:

• At-least-once delivery guaranteed
• receiver.ts verifies signatures before processing
• Retry-safe idempotency checks in webhook/payment handlers

Risk: None. Retry + signature verification = inherently safe.

3. ️ Vercel Serverless Functions

Shutdown: Max execution (10s Hobby, 60s Pro, 900s Enterprise). On redeployment:

1. Active requests complete (up to timeout)
2. New requests route to new deployment immediately
3. No SIGTERM to individual functions — they complete or timeout

Data Safety:

• Drizzle transactions for multi-step operations
• Webhook idempotency via webhook_logs success skip, active-processing skip, and failed/stale retry
• Server Actions return { success: false } on timeout — no partial state

Risk: Low. Stateless = no in-process state survives between invocations.

4. ️ Database (Drizzle + PostgreSQL)

Shutdown: Connection pool via postgres driver:

1. Pool drains active queries
2. Idle connections closed
3. Driver handles cleanup automatically

Data Safety:

• ACID transactions — partial commits impossible
• Pool exhaustion returns error, doesn't corrupt
• RLS enforces integrity regardless of connection state

Risk: Minimal. PostgreSQL ACID guarantees prevent corruption.

5. Supabase Realtime

Shutdown: Subscriptions are client-side (browser). Server maintains no persistent WebSocket connections.

Risk: None server-side. Client auto-reconnects via Supabase SDK.

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Deployment Checklist

1. Zero-downtime — Vercel handles blue-green deployments automatically
2. Migrations — Run via drizzle-kit push before deploying new code
3. Env vars — Update in Vercel dashboard before deployment
4. Feature flags — Gate new features via lib/config.ts during rollout

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Monitoring

• Sentry — captures unhandled exceptions during shutdown
• QStash dashboard — delivery status + retry attempts
• Trigger.dev dashboard — job completion + failure rates
• auth_events — security events with timestamps for post-incident analysis

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