start working on the frontend side

PHASE-D-PLAN.md

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+# Phase D: Backend Hardening & Observability - Implementation Plan
+
+## 🎯 Overview
+
+**Status**: Ready to Start  
+**Phase**: D - Backend Hardening & Observability  
+**Goal**: Production-grade security, performance, and reliability
+
+---
+
+## ✅ Already Completed (from Phase C)
+
+- ✅ Enhanced monitoring (alerting engine, metrics, WebSocket)
+- ✅ Alerting engine with rule-based monitoring
+- ✅ Metrics collection for all components
+- ✅ WebSocket event streaming
+
+---
+
+## 📋 Phase D Tasks
+
+### 1. Security Hardening 🔒
+
+#### 1.1 Password Hashing
+- **Current**: Argon2id implementation is stubbed
+- **Task**: Implement proper Argon2id password hashing
+- **Priority**: High
+- **Files**: `backend/internal/auth/handler.go`
+
+#### 1.2 Token Hashing
+- **Current**: Session token hashing is simplified
+- **Task**: Implement cryptographic hash for session tokens
+- **Priority**: High
+- **Files**: `backend/internal/auth/handler.go`
+
+#### 1.3 Rate Limiting
+- **Current**: Not implemented
+- **Task**: Add rate limiting middleware
+- **Priority**: Medium
+- **Files**: `backend/internal/common/router/middleware.go`
+
+#### 1.4 CORS Configuration
+- **Current**: Allows all origins
+- **Task**: Make CORS configurable via config file
+- **Priority**: Medium
+- **Files**: `backend/internal/common/router/router.go`, `backend/internal/common/config/config.go`
+
+#### 1.5 Input Validation
+- **Current**: Basic validation
+- **Task**: Enhanced input validation for all endpoints
+- **Priority**: Medium
+- **Files**: All handlers
+
+#### 1.6 Security Headers
+- **Current**: Not implemented
+- **Task**: Add security headers middleware (X-Frame-Options, X-Content-Type-Options, etc.)
+- **Priority**: Medium
+- **Files**: `backend/internal/common/router/middleware.go`
+
+---
+
+### 2. Performance Optimization ⚡
+
+#### 2.1 Database Query Optimization
+- **Current**: Basic queries
+- **Task**: Optimize database queries (indexes, query plans)
+- **Priority**: Medium
+- **Files**: All service files
+
+#### 2.2 Connection Pooling
+- **Current**: Basic connection pool
+- **Task**: Optimize database connection pool settings
+- **Priority**: Low
+- **Files**: `backend/internal/common/database/database.go`
+
+#### 2.3 Response Caching
+- **Current**: No caching
+- **Task**: Add caching for read-heavy endpoints (health, metrics, etc.)
+- **Priority**: Low
+- **Files**: `backend/internal/common/router/middleware.go`
+
+#### 2.4 Request Timeout Configuration
+- **Current**: Basic timeouts
+- **Task**: Fine-tune request timeouts per endpoint type
+- **Priority**: Low
+- **Files**: `backend/internal/common/router/router.go`
+
+---
+
+### 3. Comprehensive Testing 🧪
+
+#### 3.1 Unit Tests
+- **Current**: No unit tests
+- **Task**: Write unit tests for core services
+- **Priority**: High
+- **Files**: `backend/internal/*/service_test.go`
+
+#### 3.2 Integration Tests
+- **Current**: Manual testing scripts
+- **Task**: Automated integration tests
+- **Priority**: Medium
+- **Files**: `backend/tests/integration/`
+
+#### 3.3 Load Testing
+- **Current**: Not tested
+- **Task**: Load testing for API endpoints
+- **Priority**: Low
+- **Files**: `scripts/load-test.sh`
+
+#### 3.4 Security Testing
+- **Current**: Not tested
+- **Task**: Security vulnerability scanning
+- **Priority**: Medium
+- **Files**: Security test suite
+
+---
+
+### 4. Error Handling Enhancement 🛡️
+
+#### 4.1 Error Messages
+- **Current**: Some error messages could be more specific
+- **Task**: Improve error messages with context
+- **Priority**: Low
+- **Files**: All handlers and services
+
+#### 4.2 Error Logging
+- **Current**: Basic error logging
+- **Task**: Enhanced error logging with stack traces
+- **Priority**: Low
+- **Files**: `backend/internal/common/logger/logger.go`
+
+---
+
+## 🎯 Implementation Order
+
+### Priority 1: Security Hardening (Critical)
+1. Password Hashing (Argon2id)
+2. Token Hashing (Cryptographic)
+3. Rate Limiting
+4. CORS Configuration
+
+### Priority 2: Testing (Important)
+1. Unit Tests for core services
+2. Integration Tests for API endpoints
+3. Security Testing
+
+### Priority 3: Performance (Nice to Have)
+1. Database Query Optimization
+2. Response Caching
+3. Connection Pool Tuning
+
+### Priority 4: Polish (Enhancement)
+1. Error Message Improvements
+2. Security Headers
+3. Input Validation Enhancements
+
+---
+
+## 📊 Success Criteria
+
+### Security
+- ✅ Argon2id password hashing implemented
+- ✅ Cryptographic token hashing
+- ✅ Rate limiting active
+- ✅ CORS configurable
+- ✅ Security headers present
+
+### Testing
+- ✅ Unit test coverage >70%
+- ✅ Integration tests for all endpoints
+- ✅ Security tests passing
+
+### Performance
+- ✅ Database queries optimized
+- ✅ Response times <100ms for read operations
+- ✅ Connection pool optimized
+
+---
+
+## 🚀 Ready to Start
+
+**Next Task**: Security Hardening - Password Hashing (Argon2id)
+
+Would you like to start with:
+1. **Security Hardening** (Password Hashing, Token Hashing, Rate Limiting)
+2. **Comprehensive Testing** (Unit Tests, Integration Tests)
+3. **Performance Optimization** (Database, Caching)
+
+Which would you like to tackle first?
+