# CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

## Project Overview

Claude Code Monitor is a real-time monitoring dashboard for tracking Claude Code activity through a hook-based event capture system. It consists of a FastAPI backend, React/TypeScript frontend, and shell scripts that integrate with Claude Code's hook system.

## Architecture

### Event Flow
```
Claude Code → Hook Scripts (.claude/hooks/*.sh)
    → FastAPI Backend (Python/SQLAlchemy/WebSockets)
    → SQLite Database
    → WebSocket broadcast → React Frontend
```

### Key Components

**Backend** (`backend/app/`):
- `main.py` - FastAPI application entry point with CORS, routers, health checks
- `database.py` - SQLAlchemy models (Event, Session, Statistics, ToolUsage), database initialization
- `websocket.py` - ConnectionManager class for broadcasting events to connected clients
- `crud.py` - Database CRUD operations and statistics calculations
- `schemas.py` - Pydantic models for request/response validation
- `api/events.py` - Event creation and listing endpoints
- `api/statistics.py` - Statistics aggregation endpoints
- `api/websocket_endpoint.py` - WebSocket connection handling

**Frontend** (`frontend/src/`):
- `App.tsx` - Main component orchestrating WebSocket, events, statistics, and filtering
- `hooks/useWebSocket.ts` - WebSocket connection management with auto-reconnect
- `hooks/useEvents.ts` - Event list management with pagination
- `hooks/useStatistics.ts` - Statistics state management
- `types/index.ts` - TypeScript type definitions and filter mappings
- `components/` - React components for UI (Header, EventFeed, StatisticsCards, etc.)

**Hook Scripts** (`.claude/hooks/`):
Six bash scripts that capture Claude Code events and POST JSON to the backend via curl:
- `pre_tool_use.sh` / `post_tool_use.sh` - Tool execution tracking
- `session_start.sh` / `session_end.sh` - Session lifecycle
- `subagent_stop.sh` - Agent completion tracking
- `user_prompt.sh` - User prompt submission tracking

All hooks use `jq` for JSON parsing and send data asynchronously (non-blocking) to `http://localhost:8000/api/events`.

## Common Commands

### Development

**Backend** (requires Python 3.11+):
```bash
cd backend
python -m venv venv
source venv/bin/activate
pip install -r requirements.txt
python -m app.main  # Runs on http://localhost:8000
```

**Frontend** (requires Node.js):
```bash
cd frontend
npm install
npm run dev  # Runs on http://localhost:5173
npm run build  # Production build
npm run lint  # ESLint check
```

### Docker Deployment

```bash
# Build and start both services
docker-compose up --build

# Start in detached mode
docker-compose up -d

# View logs
docker-compose logs -f backend
docker-compose logs -f frontend

# Stop services
docker-compose down

# Reset database (stops containers, removes database, restarts)
docker-compose down && rm -f data/claude_monitor.db* && docker-compose up -d
```

### Testing Hook Installation

```bash
# Install hooks to ~/.claude/hooks/
./install_hooks.sh

# Test hook manually
echo '{"session_id":"test","tool_name":"Bash","timestamp":1234567890}' | ~/.claude/hooks/post_tool_use.sh

# Verify backend received it
curl http://localhost:8000/api/events | jq
```

## Database Schema

**SQLAlchemy 2.0 Compatibility**: Uses explicit `text()` for raw SQL, proper relationship configurations, and modern declarative syntax.

**Tables**:
- `events` - All captured events with indexes on session_id, event_type, tool_name, timestamp
- `sessions` - Session tracking with start/end times and event counts
- `statistics` - Single-row cache table (id=1) for dashboard stats
- `tool_usage` - Per-tool usage counters with first/last usage timestamps

**SQLite Configuration**: WAL mode enabled for better concurrency in `init_db()`.

## Event Types

| Event Type | Source Hook | Description | Frontend Filter |
|------------|-------------|-------------|-----------------|
| `PreToolUse` | pre_tool_use.sh | Before tool execution | TOOLS |
| `PostToolUse` | post_tool_use.sh | After tool execution | TOOLS |
| `SessionStart` | session_start.sh | Session started | SESSIONS |
| `SessionEnd` | session_end.sh | Session ended | SESSIONS |
| `SubagentStop` | subagent_stop.sh | Agent completed | AGENTS |
| `UserPromptSubmit` | user_prompt.sh | User prompt submitted | PROMPTS |

## Port Configuration

- **Backend**: 8000 (FastAPI/Uvicorn)
- **Frontend (dev)**: 5173 (Vite dev server)
- **Frontend (prod)**: 3000 (nginx in Docker)

Change ports in `docker-compose.yml` if conflicts occur.

## Key Implementation Details

### WebSocket Protocol
- Backend broadcasts three message types: `event_created`, `stats_updated`, `stats_reset`
- Frontend auto-reconnects on disconnect with exponential backoff
- Heartbeat ping/pong every 30 seconds to maintain connection

### Frontend State Management
- Events stored in reverse chronological order (newest first)
- Pagination loads 50 events at a time
- Filter changes trigger new API fetch (events reset)
- Statistics updated via WebSocket broadcasts, not polling

### Hook Performance
- All hooks run curl in background (`&`) to avoid blocking Claude Code
- 2-second timeout on HTTP requests
- Silent mode prevents stderr noise in Claude Code output
- Uses `jq` for JSON construction to handle escaping correctly

### TypeScript Build
The frontend uses strict TypeScript with proper type definitions in `types/index.ts`. When making changes:
- Run `npm run build` to check for type errors before committing
- Event types must match backend Pydantic models
- Filter mappings in `EVENT_FILTER_MAP` must stay synchronized with backend event types

## Configuration Files

- `docker-compose.yml` - Service orchestration, volumes, network setup
- `backend/requirements.txt` - Python dependencies (FastAPI, SQLAlchemy 2.0, uvicorn, websockets)
- `frontend/package.json` - Node dependencies (React 18, Vite, TypeScript, Axios)
- `frontend/vite.config.ts` - Vite build configuration with React plugin
- `frontend/tsconfig.json` - TypeScript compiler options

## Debugging

### Backend Issues
```bash
# Check backend health
curl http://localhost:8000/health

# View API documentation
open http://localhost:8000/docs

# Check database
sqlite3 data/claude_monitor.db "SELECT COUNT(*) FROM events;"

# Tail backend logs
docker-compose logs -f backend
```

### Frontend Issues
```bash
# Check WebSocket connection in browser console
# Should show "WebSocket connected" message

# Verify API connectivity
curl http://localhost:8000/api/statistics

# Check for CORS errors in browser DevTools Network tab
```

### Hook Issues
```bash
# Verify jq is installed
which jq  # Should print path, not "not found"

# Check hooks are executable
ls -la ~/.claude/hooks/

# Test hook with verbose output (remove --silent from curl)
echo '{"session_id":"test"}' | ~/.claude/hooks/session_start.sh
```