feat: Implement structured logging with request correlation IDs (#63)

[olaleyeolajide81-sketch]

This commit implements structured logging with correlation IDs to enable request tracing across services and provides JSON log format suitable for log aggregation tools like ELK and Datadog.

Changes Made:

1. Created Request Context Middleware

• backend/src/middleware/requestContext.ts (TypeScript)
• backend/src/middleware/requestContext.js (JavaScript)
  • Reads X-Correlation-ID header or generates new UUID
  • Attaches correlation ID to request object
  • Adds X-Correlation-ID to response headers
  • Tracks request start time for duration logging
  • Includes sensitive data redaction function
  • Provides requestDurationLogger middleware for endpoint timing

2. Enhanced Logger Utility (TypeScript)

• backend/src/utils/logger.ts
  • Added JSON structured log format for production
  • Added pretty format for development with colorization
  • Implemented correlation ID propagation in log entries
  • Added sensitive data redaction (passwords, tokens, etc.)
  • File logs always use JSON format for aggregation
  • Added createChildLogger function for correlation ID scoping
  • Log level configurable via LOG_LEVEL environment variable

3. Enhanced Logger Utility (JavaScript)

• backend/src/utils/logger.js
  • Aligned with TypeScript logger implementation
  • Added JSON structured log format for production
  • Added pretty format for development
  • Implemented correlation ID propagation
  • Added sensitive data redaction
  • File logs always use JSON format
  • Added createChildLogger function
  • Maintained security.log transport

4. Updated Main Application Entry Point

• backend/src/index.js
  • Imported requestContext and requestDurationLogger middleware
  • Mounted requestContext middleware early in middleware chain
  • Updated request logging to include correlation ID
  • Ensures correlation ID is available to all downstream middleware

Definition of Done Checklist:

✅ X-Correlation-ID header read or generated per request ✅ Correlation ID propagated to all downstream log entries ✅ JSON structured log format with timestamp, level, correlationId, message, metadata ✅ Sensitive data (passwords, tokens) redacted from logs ✅ Request duration logged for each endpoint (via requestDurationLogger) ✅ Log level configurable via LOG_LEVEL environment variable

Technical Details:

• Correlation IDs are generated using UUID v4
• JSON format is used in production (NODE_ENV=production)
• Pretty format with colors is used in development
• File logs always use JSON format regardless of environment
• Sensitive fields: password, token, apiKey, secret, authorization, creditCard, ssn, socialSecurityNumber
• Request duration can be logged using requestDurationLogger middleware (optional)
• Log levels: error, warn, info, http, debug

Files Modified:

• backend/src/utils/logger.ts
• backend/src/utils/logger.js
• backend/src/middleware/requestContext.ts (new)
• backend/src/middleware/requestContext.js (new)
• backend/src/index.js

Closes #63

Description

Related Issue

Closes #

Type of Change

• 🐛 Bug fix (non-breaking change that fixes an issue)
• ✨ New feature (non-breaking change that adds functionality)
• 💥 Breaking change (fix or feature that changes existing behavior)
• 📚 Documentation update
• ♻️ Refactor (no functional change)
• 🧪 Tests
• 🔧 Chore / tooling

Packages Affected

• contracts/ (Soroban / Rust)
• backend/ (Node / Express)
• frontend/ (Next.js)
• docs/

How Has This Been Tested?

Checklist

• My code follows the project's coding standards (see CONTRIBUTING.md)
• I have run the relevant linters and type checks
• I have added or updated tests that prove my change works
• All new and existing tests pass locally
• I have updated documentation where needed
• My commits follow the Conventional Commits format
• I have noted any breaking changes below (or there are none)

Breaking Changes

None

Additional Notes / Screenshots

closes #63