Backend Engineering

Improve conversation database design with a bounded state row and an indexed context query. Inspect real SQLite query plans in the runnable example.

Build a transactional outbox Node.js example that saves orders and events together. Test rollback, relay replay and consumer deduplication with SQLite.

Use Node.js latency tracing to separate queue wait, database time and external calls. Build a local span recorder and plan production instrumentation.

Build a retry budget Node.js policy with deadlines, bounded attempts and jitter. Stop nested retries from multiplying load during dependency failures.

Diagnose background job queue latency beyond fast API responses. Build deadline-aware scheduling and expose expired work with a Node.js simulation.

Prevent a Node.js cache stampede with in-flight request sharing and explicit freshness rules. Test simultaneous misses without making distributed-lock claims.