pr-description.md

Pull Request Description

Overview

This PR implements request-scoped logging context (req.log) on Express request objects. Route handlers and middlewares can now call req.log.info(), req.log.warn(), req.log.error(), or req.log.debug() to emit structured logs with the correct request metadata (requestId, correlationId, route, tenant, and actor) automatically populated. This resolves workarounds where context was lost during event loop execution.

Key Additions & Changes

1. Request Logger Types & Helpers (src/types/express.d.ts, src/utils/logger.ts):

   • Augment Express Request type definition to expose the log: RequestLogger property.
   • Implement createRequestLogger in logger.ts to format logs with a custom/explicit context Map.
   • Update logger methods (info, warn, error, debug) to accept redactionContext parameters.

2. Middleware Attachment (src/middleware/requestId.ts):

   • Instantiate and bind req.log to a Proxy wrapper over the request tracing context.
   • The Proxy implements dynamic fallback lookup for tenant and actor IDs from the request header/user properties, allowing downstream auth middlewares to cleanly update the logging context.

3. ESLint Plugin Update (src/observability/eslint-plugin-logger-schema.ts):

   • Modified the custom ESLint rules to parse and validate both logger.x() and req.log.x() expressions. This ensures that req.log calls conform to the allowlist PII schema validations.

4. Documentation:

   • Updated README.md, docs/LOGGING.md, and docs/observability.md to document the new req.log logger, including example usages.

5. Tests:

   • Added src/middleware/__tests__/requestLogger.test.ts to test request context binding, dynamic updating of tenant/actor context, and deferred logging outside request lifecycles.

Closes #866