@iota-big3/sdk-gateway/CHANGELOG.md

Universal API Gateway with protocol translation, intelligent routing, rate limiting, health checking, and caching

# Changelog

All notable changes to `@iota-big3/sdk-gateway` will be documented in this file.

## [2.1.1] - 2025-07-25

### Fixed

- **TypeScript Configuration**: Resolved 40 compilation errors related to monorepo imports
  - Root cause: `rootDir` was restricting imports from other packages
  - Solution: Updated `tsconfig.build.json` to set `rootDir: "../.."`
  - Result: Full TypeScript health restored (0 errors)

### Added

- **Phase 2.5 Documentation**: Comprehensive audit results and lessons learned
  - Core competency assessment: Grade A- (90%)
  - Detailed technical analysis of the fix
  - Next steps for Phase 2f, 2h, and 3

## [2.1.0] - 2024-07-24

### Added (Phase 2k - Production Readiness)

- **Chaos Engineering Framework**: Production-grade failure injection system
  - Network latency simulation with configurable delays
  - Service failure injection (HTTP error codes)
  - Request timeout simulation
  - Resource exhaustion simulation (CPU, memory, connections)
  - Response corruption (truncated, invalid JSON, empty, huge)
  - Deterministic chaos with seed support
  - Real-time statistics and event emissions
  - Enable/disable controls at runtime
- **Performance Monitoring**: Enterprise-grade metrics and anomaly detection
  - Request metrics tracking (rate, latency percentiles, active connections)
  - Error rate monitoring with configurable thresholds
  - Resource monitoring (CPU, memory usage)
  - Throughput measurements
  - Anomaly detection algorithms:
    - Latency spike detection
    - Memory leak identification
    - Error rate threshold monitoring
    - Throughput degradation alerts
  - Real-time metric collection
  - Event emission for critical anomalies
- **Production Smoke Tests**: Automated deployment validation
  - Health check endpoint validation
  - Service discovery verification
  - Request routing tests
  - Rate limiting functionality checks
  - Circuit breaker validation
  - Cache operation tests
  - Authentication verification
  - Metrics endpoint validation
  - Parallel/sequential execution modes
  - Critical test prioritization
  - Comprehensive reporting with pass rates
- **Documentation**: Comprehensive production deployment guide
  - Chaos engineering examples
  - Performance monitoring integration
  - Smoke test automation
  - Production configuration best practices

### Improved

- **Type Safety**: All new components with full TypeScript support
- **Testing**: Comprehensive test coverage for chaos middleware
- **Examples**: Added production-ready demo showcasing all Phase 2k features
- **API Documentation**: Updated with new production readiness APIs

## [2.0.0-beta.1] - 2024-07-21

### Added (Phase 2g - Safe Feature Enhancement)

- **Rate Limiting**: Configurable request rate limiting with custom key generation
  - Window-based rate limiting with configurable duration and max requests
  - Custom key generator support for user/IP/route-based limiting
  - Skip conditions for whitelisting paths
  - Events for rate limit violations
- **Health Checking**: Active service health monitoring
  - Periodic health checks with configurable intervals
  - Custom health check functions
  - Retry logic with exponential backoff
  - Overall gateway health status reporting
- **Response Caching**: Intelligent caching with multiple strategies
  - LRU (Least Recently Used), LFU (Least Frequently Used), and FIFO strategies
  - TTL management with per-entry expiration
  - Cache invalidation by pattern and tags
  - Cache statistics and hit rate tracking
  - Pluggable cache stores (Redis/Memcached support)
- **Gateway Management Features**:
  - Dynamic enable/disable functionality
  - Runtime configuration updates
  - Route management (add/remove routes dynamically)
  - Enhanced metrics with cache and rate limit statistics

### Changed (Phase 2d - Subfolder-Level Clean Rebuild)

- Rebuilt corrupted modules with clean architecture:
  - `http-adapter` - Clean HTTP protocol adapter implementation
  - `response-aggregator` - Improved aggregation logic
  - `service-registry` - Enhanced service discovery
  - `gateway-manager` - Centralized gateway management
- Improved type definitions with better type safety
- Enhanced error handling across all modules

### Fixed (Phase 2f - Lint Quality Enhancement)

- Fixed all TypeScript compilation errors (0 errors)
- Resolved ESLint issues:
  - Replaced `any` types with proper type definitions
  - Fixed unused variables with underscore prefix convention
  - Added proper null/undefined checks
  - Improved type safety in test files

### Improved

- **Performance**: Optimized request handling pipeline
- **Memory Usage**: Better cleanup and resource management
- **Type Safety**: Stricter TypeScript configuration
- **Test Coverage**: Comprehensive test suite with 42 tests
- **Documentation**: Updated with all new features and examples

### Technical Details

- **Phase 2b**: Clean rebuild approach was considered but Phase 2d was chosen
- **Phase 2d**: Successfully rebuilt 4 corrupted modules
- **Phase 2e**: File-level fixes applied to remaining issues
- **Phase 2f**: Systematic lint cleanup after TypeScript fixes
- **Phase 2g**: Safe feature enhancement with backward compatibility
- **Phase 2k**: Production readiness with chaos engineering and monitoring

## [1.0.0] - Previous Version

### Initial Features

- Multi-protocol support (HTTP, gRPC, WebSocket, GraphQL)
- Basic routing engine
- Circuit breaker pattern
- SLA monitoring
- Cost tracking
- Service discovery (static, Kubernetes, Consul)

---

## Migration Guide

### From 2.0 to 2.1 (Phase 2k)

The Phase 2k update is fully backward compatible. To use the new production features:

1. **Enable Chaos Engineering** (staging/testing only):

   ```typescript
   import { ChaosMiddleware } from "@iota-big3/sdk-gateway";

   const chaos = new ChaosMiddleware({
     enabled: process.env.NODE_ENV === "staging",
     failures: {
       networkLatency: { probability: 0.1, minMs: 100, maxMs: 500 },
     },
   });

   gateway.use(chaos);
   ```

2. **Add Performance Monitoring**:

   ```typescript
   import { PerformanceMonitor } from "@iota-big3/sdk-gateway";

   const monitor = new PerformanceMonitor({
     latency: { p95: 150 },
     errorRate: 0.01,
   });

   monitor.on("anomaly:critical", (anomaly) => {
     // Handle critical anomaly
   });
   ```

3. **Implement Smoke Tests**:

   ```typescript
   import { runSmokeTests } from "@iota-big3/sdk-gateway";

   // In your deployment pipeline
   const results = await runSmokeTests(gatewayUrl);
   if (results.some((r) => !r.passed)) {
     throw new Error("Deployment validation failed");
   }
   ```

### From 1.x to 2.0

1. **Configuration Changes**:

   ```typescript
   // Old
   const gateway = createGateway({
     protocols: ["http"],
     port: 8080,
   });

   // New
   const gateway = createGateway({
     name: "My Gateway",
     port: 8080,
     rateLimit: { windowMs: 60000, max: 100 },
     healthCheck: { interval: 30000 },
     caching: { enabled: true, ttl: 300 },
   });
   ```

2. **Service Registration**:

   ```typescript
   // Old
   gateway.registerService({
     id: "service-1",
     url: "http://localhost:3000",
   });

   // New
   gateway.registerService({
     id: "service-1",
     name: "my-service",
     host: "localhost",
     port: 3000,
     protocol: "http",
     healthCheck: "/health",
   });
   ```

3. **New Features**:
   - Use `gateway.getRateLimiter()` for rate limit management
   - Use `gateway.getHealthChecker()` for health monitoring
   - Use `gateway.getCacheManager()` for cache control