## Backend Logging Configuration

### Files Modified with Comprehensive Logging:

#### 1. **app/logger.py** (NEW)
- Centralized logging configuration
- Standardized log format with timestamps
- DEBUG, INFO, WARNING, ERROR levels

#### 2. **main.py**
- Application startup/shutdown logs
- Qdrant initialization logging with error handling
- Root endpoint access logs

#### 3. **app/api/v1_endpoints.py**
- POST /run endpoint: Request received, execution flow, completion status
- GET /stream endpoint: Stream start, event count, error handling
- Thread ID tracking for request correlation

#### 4. **app/agents/researcher.py**
- Search plan generation with detailed steps
- Tavily search execution per task with result count
- DuckDuckGo fallback search logging
- Total results collected
- Error logging with full stack trace

#### 5. **app/agents/critics.py**
- Source verification start with count
- Research summary preparation
- LLM invocation and feedback
- Approval vs Rejection status
- Error handling

#### 6. **app/agents/writer.py**
- Report generation start
- Research sorting and filtering
- LLM invocation for report creation
- Final report size tracking
- Error handling

#### 7. **app/agents/router.py**
- Routing decision logic
- State evaluation (iteration count, feedback presence)
- Route path (researcher loop vs writer)

#### 8. **app/agents/graph.py**
- Graph building and compilation
- Node registration logging

### Log Level Usage:
- **DEBUG** 🐛: Detailed execution flow, intermediate steps
- **INFO** ℹ️: Major milestones, request start/end, key decisions
- **WARNING** ⚠️: Non-critical issues, missing configs
- **ERROR** ❌: Exceptions with full traceback

### Emoji Indicators:
- 🚀 Startup
- 📧 API Request
- 🔴 Stream Start
- 🔍 Researcher Agent
- 💼 Research Processing
- 🔎 Search Operations
- 📊 Data Processing
- 🤖 LLM Invocation
- ✅ Success
- ❌ Error
- ⚠️ Warning
- 🔀 Routing Logic

### How to Use Logs:

1. **Monitor Live**: Watch terminal output for real-time flow
2. **Debug Issues**: Check error logs with full stack traces
3. **Track Performance**: See timing and counts for each step
4. **Verify Integration**: Confirm API connections (Tavily, DuckDuckGo, LLMs)

### Example Log Output:

```
[2026-06-09 10:15:30] [INFO] [main:16] 🚀 Application starting...
[2026-06-09 10:15:30] [INFO] [main:18] 📦 Initializing Qdrant vector database...
[2026-06-09 10:15:31] [INFO] [main:20] ✅ Qdrant initialized successfully
[2026-06-09 10:15:35] [INFO] [v1_endpoints:20] 📧 POST /run - Query: Babar Azam in psl... [Thread ID: a1b2c3d4-...]
[2026-06-09 10:15:35] [INFO] [researcher:35] 🔍 Researcher Node: Starting research for query: Babar Azam...
[2026-06-09 10:15:36] [INFO] [researcher:52] 📊 Tavily: Retrieved 6 results
[2026-06-09 10:15:37] [INFO] [researcher:60] 🦆 DuckDuckGo: Retrieved 3 results
[2026-06-09 10:15:38] [INFO] [critic:48] ✅ Critic Node: Sources APPROVED
[2026-06-09 10:15:45] [INFO] [writer:25] ✍️ Writer Node: Starting report generation for 9 sources
[2026-06-09 10:15:55] [INFO] [writer:40] ✅ Report generated: 3450 chars
[2026-06-09 10:15:55] [INFO] [v1_endpoints:31] ✅ Graph execution completed for thread a1b2c3d4-...
```

This comprehensive logging will help identify:
- Where requests fail
- Which API calls are timing out
- Missing environment variables
- Graph execution flow
- Data aggregation progress