Node.js Backend

Verify before implementing: For framework-specific APIs (Express 5, Fastify 5, Node.js 22+ built-ins), look up current docs via Context7 (query-docs) before writing code. Training data may lag current releases.

Working rules

• Validate request and third-party data before use; keep response serialization and error envelopes explicit.
• Preserve caller-visible contracts and authorization when adding resilience or fallbacks.
• Bound concurrency, set timeouts, and avoid blocking production request paths.
• Verify actual resource identity before parsing or caching a reused client's result.
• Exercise operational telemetry and failure paths, not successful return codes alone.

Architecture