# CLAUDE.md

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

## Project Overview

**CalChat** is a calendar mobile app with AI support. The core concept is managing calendar events through a chat interface with an AI chatbot. Users can add, edit, and delete events via natural language conversation.

This is a fullstack TypeScript monorepo with npm workspaces.

## Commands

### Root (monorepo)
```bash
npm install          # Install all dependencies for all workspaces
npm run format       # Format all TypeScript files with Prettier
```

### Client (apps/client) - Expo React Native app
```bash
npm run start -w @caldav/client        # Start Expo dev server
npm run android -w @caldav/client      # Start on Android
npm run ios -w @caldav/client          # Start on iOS
npm run web -w @caldav/client          # Start web version
npm run lint -w @caldav/client         # Run ESLint
```

### Server (apps/server) - Express.js backend
```bash
npm run dev -w @caldav/server          # Start dev server with hot reload (tsx watch)
npm run build -w @caldav/server        # Compile TypeScript
npm run start -w @caldav/server        # Run compiled server (port 3000)
```

## Technology Stack

| Area | Technology | Purpose |
|------|------------|---------|
| Frontend | React Native | Mobile UI Framework |
| | Expo | Development platform |
| | Expo-Router | File-based routing |
| | NativeWind | Tailwind CSS for React Native |
| | Zustand | State management |
| | FlashList | High-performance lists |
| Backend | Express.js | Web framework |
| | MongoDB | Database |
| | Mongoose | ODM |
| | GPT (OpenAI) | AI/LLM for chat |
| | JWT | Authentication |
| | pino / pino-http | Structured logging |
| | react-native-logs | Client-side logging |
| Planned | iCalendar | Event export/import |

## Architecture

### Workspace Structure
```
apps/client      - @caldav/client - Expo React Native app
apps/server      - @caldav/server - Express.js backend
packages/shared  - @caldav/shared - Shared TypeScript types and models
```

### Frontend Architecture (apps/client)

```
src/
├── app/                        # Expo-Router file-based routing
│   ├── _layout.tsx             # Root Stack layout
│   ├── index.tsx               # Entry redirect
│   ├── login.tsx               # Login screen
│   ├── register.tsx            # Registration screen
│   ├── (tabs)/                 # Tab navigation group
│   │   ├── _layout.tsx         # Tab bar configuration
│   │   ├── chat.tsx            # Chat screen (AI conversation)
│   │   └── calendar.tsx        # Calendar overview
│   ├── event/
│   │   └── [id].tsx            # Event detail screen (dynamic route)
│   └── note/
│       └── [id].tsx            # Note editor for event (dynamic route)
├── components/
│   ├── BaseBackground.tsx      # Common screen wrapper
│   ├── Header.tsx              # Header component
│   ├── EventCardBase.tsx       # Shared event card layout with icons (used by EventCard & ProposedEventCard)
│   ├── EventCard.tsx           # Calendar event card (uses EventCardBase + edit/delete buttons)
│   ├── EventConfirmDialog.tsx  # AI-proposed event confirmation modal
│   └── ProposedEventCard.tsx   # Chat event proposal (uses EventCardBase + confirm/reject buttons)
├── Themes.tsx                  # Centralized color/theme definitions
├── logging/
│   ├── index.ts                # Re-exports
│   └── logger.ts               # react-native-logs config (apiLogger, storeLogger)
├── services/
│   ├── index.ts                # Re-exports all services
│   ├── ApiClient.ts            # HTTP client with request logging (get, post, put, delete)
│   ├── AuthService.ts          # login(), register(), logout(), refresh()
│   ├── EventService.ts         # getAll(), getById(), getByDateRange(), create(), update(), delete()
│   └── ChatService.ts          # sendMessage(), confirmEvent(), rejectEvent(), getConversations(), getConversation()
└── stores/                     # Zustand state management
    ├── index.ts                # Re-exports all stores
    ├── AuthStore.ts            # user, token, isAuthenticated, login(), logout(), setToken()
    ├── ChatStore.ts            # messages[], addMessage(), addMessages(), updateMessage(), clearMessages(), chatMessageToMessageData()
    └── EventsStore.ts          # events[], setEvents(), addEvent(), updateEvent(), deleteEvent()
```

**Routing:** Tab-based navigation with Chat and Calendar as main screens. Auth screens (login, register) outside tabs. Dynamic routes for event detail and note editing.

### Backend Architecture (apps/server)

```
src/
├── app.ts                    # Entry point, DI setup, Express config
├── controllers/              # Request handlers + middleware (per architecture diagram)
│   ├── AuthController.ts     # login(), register(), refresh(), logout()
│   ├── ChatController.ts     # sendMessage(), confirmEvent(), rejectEvent(), getConversations(), getConversation()
│   ├── EventController.ts    # create(), getById(), getAll(), getByDateRange(), update(), delete()
│   ├── AuthMiddleware.ts     # authenticate() - JWT validation
│   └── LoggingMiddleware.ts  # httpLogger - pino-http request logging
├── logging/
│   ├── index.ts              # Re-exports
│   ├── logger.ts             # pino config with redact for sensitive data
│   └── Logged.ts             # @Logged() class decorator for automatic method logging
├── routes/                   # API endpoint definitions
│   ├── index.ts              # Combines all routes under /api
│   ├── auth.routes.ts        # /api/auth/*
│   ├── chat.routes.ts        # /api/chat/* (protected)
│   └── event.routes.ts       # /api/events/* (protected)
├── services/                 # Business logic
│   ├── interfaces/           # DB-agnostic interfaces (for dependency injection)
│   │   ├── AIProvider.ts     # processMessage()
│   │   ├── UserRepository.ts # + CreateUserData (server-internal DTO)
│   │   ├── EventRepository.ts
│   │   └── ChatRepository.ts
│   ├── AuthService.ts
│   ├── ChatService.ts
│   └── EventService.ts
├── repositories/             # Data access (DB-specific implementations)
│   ├── index.ts              # Re-exports from ./mongo
│   └── mongo/                # MongoDB implementation
│       ├── models/           # Mongoose schemas
│       │   ├── types.ts      # Shared types (IdVirtual interface)
│       │   ├── UserModel.ts
│       │   ├── EventModel.ts
│       │   └── ChatModel.ts
│       ├── MongoUserRepository.ts
│       ├── MongoEventRepository.ts
│       └── MongoChatRepository.ts
├── ai/
│   ├── GPTAdapter.ts         # Implements AIProvider using OpenAI GPT
│   ├── index.ts              # Re-exports GPTAdapter
│   └── utils/                # Shared AI utilities (provider-agnostic)
│       ├── index.ts          # Re-exports
│       ├── eventFormatter.ts # formatExistingEvents() for system prompt
│       ├── systemPrompt.ts   # buildSystemPrompt() - German calendar assistant prompt
│       ├── toolDefinitions.ts # TOOL_DEFINITIONS - provider-agnostic tool specs
│       └── toolExecutor.ts   # executeToolCall() - handles getDay, proposeCreate/Update/Delete, searchEvents
└── utils/
    ├── jwt.ts                # signToken(), verifyToken()
    ├── password.ts           # hash(), compare()
    ├── eventFormatters.ts    # getWeeksOverview(), getMonthOverview() - formatted event listings
    └── recurrenceExpander.ts # expandRecurringEvents() - expand recurring events into occurrences
```

**API Endpoints:**
- `POST /api/auth/login` - User login
- `POST /api/auth/register` - User registration
- `POST /api/auth/refresh` - Refresh JWT token
- `POST /api/auth/logout` - User logout
- `GET /api/events` - Get all events (protected)
- `GET /api/events/range` - Get events by date range (protected)
- `GET /api/events/:id` - Get single event (protected)
- `POST /api/events` - Create event (protected)
- `PUT /api/events/:id` - Update event (protected)
- `DELETE /api/events/:id` - Delete event (protected)
- `POST /api/chat/message` - Send message to AI (protected)
- `POST /api/chat/confirm/:conversationId/:messageId` - Confirm proposed event (protected)
- `POST /api/chat/reject/:conversationId/:messageId` - Reject proposed event (protected)
- `GET /api/chat/conversations` - Get all conversations (protected)
- `GET /api/chat/conversations/:id` - Get messages of a conversation with cursor-based pagination (protected)
- `GET /health` - Health check
- `POST /api/ai/test` - AI test endpoint (development only)

### Shared Package (packages/shared)

```
src/
├── index.ts
├── models/
│   ├── index.ts
│   ├── User.ts           # User, CreateUserDTO, LoginDTO, AuthResponse
│   ├── CalendarEvent.ts  # CalendarEvent, CreateEventDTO, UpdateEventDTO, ExpandedEvent
│   ├── ChatMessage.ts    # ChatMessage, Conversation, SendMessageDTO, CreateMessageDTO,
│   │                     # GetMessagesOptions, ChatResponse, ConversationSummary,
│   │                     # ProposedEventChange, EventAction, RespondedAction, UpdateMessageDTO
│   └── Constants.ts      # DAYS, MONTHS, Day, Month, DAY_INDEX, DAY_INDEX_TO_DAY,
│                         # DAY_TO_GERMAN, DAY_TO_GERMAN_SHORT, MONTH_TO_GERMAN
└── utils/
    ├── index.ts
    └── dateHelpers.ts    # getDay() - get date for specific weekday relative to today
```

**Key Types:**
- `User`: id, email, displayName, passwordHash?, createdAt?, updatedAt?
- `CalendarEvent`: id, userId, title, description?, startTime, endTime, note?, isRecurring?, recurrenceRule?
- `ExpandedEvent`: Extends CalendarEvent with occurrenceStart, occurrenceEnd (for recurring event instances)
- `ChatMessage`: id, conversationId, sender ('user' | 'assistant'), content, proposedChange?, respondedAction?
- `ProposedEventChange`: action ('create' | 'update' | 'delete'), eventId?, event?, updates?
- `Conversation`: id, userId, createdAt?, updatedAt? (messages loaded separately via lazy loading)
- `CreateEventDTO`: Used for creating events AND for AI-proposed events
- `GetMessagesOptions`: Cursor-based pagination with `before?: string` and `limit?: number`
- `ConversationSummary`: id, lastMessage?, createdAt? (for conversation list)
- `UpdateMessageDTO`: respondedAction? (for marking messages as confirmed/rejected)
- `RespondedAction`: 'confirm' | 'reject' (tracks user response to proposed events)
- `Day`: "Monday" | "Tuesday" | ... | "Sunday"
- `Month`: "January" | "February" | ... | "December"

### Database Abstraction

The repository pattern allows swapping databases:
- **Interfaces** (`services/interfaces/`) are DB-agnostic
- **Implementations** (`repositories/mongo/`) are DB-specific
- To add MySQL: create `repositories/mysql/` with TypeORM entities

### Mongoose Model Pattern

All Mongoose models use a consistent pattern for TypeScript-safe `id` virtuals:

```typescript
import { IdVirtual } from './types';

const Schema = new Schema<Doc, Model<Doc, {}, {}, IdVirtual>, {}, {}, IdVirtual>(
  { /* fields */ },
  {
    virtuals: {
      id: {
        get() { return this._id.toString(); }
      }
    },
    toJSON: {
      virtuals: true,
      transform: (_, ret) => {
        delete ret._id;
        delete ret.__v;
        return ret;
      }
    }
  }
);
```

Repositories use `doc.toJSON() as unknown as Type` casting (required because Mongoose's TypeScript types don't reflect virtual fields in toJSON output).

### Logging

Structured logging with pino (server) and react-native-logs (client).

**Server Logging:**
- `pino` with `pino-pretty` for development, JSON in production
- `pino-http` middleware logs all HTTP requests (method, path, status, duration)
- `@Logged()` class decorator for automatic method logging on repositories and services
- Sensitive data (password, token, etc.) automatically redacted via pino's `redact` config

**@Logged Decorator Pattern:**
```typescript
@Logged("MongoEventRepository")
export class MongoEventRepository implements EventRepository { ... }

@Logged("GPTAdapter")
export class GPTAdapter implements AIProvider { ... }
```

The decorator uses a Proxy to intercept method calls lazily, preserves sync/async nature, and logs start/completion/failure with duration.

**Client Logging:**
- `react-native-logs` with namespaced loggers (apiLogger, storeLogger)
- ApiClient logs all requests with method, endpoint, status, duration
- Log level: debug in __DEV__, warn in production

## MVP Feature Scope

### Must-Have
- Chat interface with AI assistant (text input) for event management
- Calendar overview
- Manual event CRUD (without AI)
- View completed events
- Simple reminders
- One note per event
- Recurring events

### Nice-to-Have
- iCalendar import/export
- Multiple calendars
- CalDAV synchronization with external services

## Development Environment

### MongoDB (Docker)
```bash
cd apps/server/docker/mongo
docker compose up -d                  # Start MongoDB + Mongo Express
docker compose down                   # Stop services
```
- MongoDB: `localhost:27017` (root/mongoose)
- Mongo Express UI: `localhost:8083` (admin/admin)

### Environment Variables
Server requires `.env` file in `apps/server/`:
```
JWT_SECRET=your-secret-key
JWT_EXPIRES_IN=1h
MONGODB_URI=mongodb://root:mongoose@localhost:27017/calchat?authSource=admin
OPENAI_API_KEY=sk-proj-...
USE_TEST_RESPONSES=false    # true = static test responses, false = real GPT AI
LOG_LEVEL=debug             # debug | info | warn | error | fatal
NODE_ENV=development        # development = pretty logs, production = JSON
```

## Current Implementation Status

**Backend:**
- **Implemented:**
  - `AuthController`: login(), register() with error handling
  - `AuthService`: login(), register() with password validation
  - `MongoUserRepository`: findByEmail(), create()
  - `utils/password`: hash(), compare() using bcrypt
  - `utils/jwt`: signToken() (verifyToken() pending)
  - `dotenv` integration for environment variables
  - `ChatController`: sendMessage(), confirmEvent(), rejectEvent()
  - `ChatService`: processMessage() with test responses (create, update, delete actions), confirmEvent() handles all CRUD actions
  - `MongoEventRepository`: Full CRUD implemented (findById, findByUserId, findByDateRange, create, update, delete)
  - `EventController`: Full CRUD (create, getById, getAll, getByDateRange, update, delete)
  - `EventService`: Full CRUD with recurring event expansion via recurrenceExpander
  - `utils/eventFormatters`: getWeeksOverview(), getMonthOverview() with German localization
  - `utils/recurrenceExpander`: expandRecurringEvents() using rrule library for RRULE parsing
  - `ChatController`: getConversations(), getConversation() with cursor-based pagination support
  - `ChatService`: getConversations(), getConversation(), processMessage() uses real AI or test responses (via USE_TEST_RESPONSES), confirmEvent()/rejectEvent() update respondedAction and persist response messages
  - `MongoChatRepository`: Full CRUD implemented (getConversationsByUser, createConversation, getMessages with cursor pagination, createMessage, updateMessage)
  - `ChatRepository` interface: updateMessage() added for respondedAction tracking
  - `GPTAdapter`: Full implementation with OpenAI GPT (gpt-5-mini model), function calling for calendar operations
  - `ai/utils/`: Provider-agnostic shared utilities (systemPrompt, toolDefinitions, toolExecutor, eventFormatter)
  - `logging/`: Structured logging with pino, pino-http middleware, @Logged decorator
  - All repositories and GPTAdapter decorated with @Logged for automatic method logging
- **Stubbed (TODO):**
  - `AuthMiddleware.authenticate()`: Currently uses fake user for testing
  - `AuthController`: refresh(), logout()
  - `AuthService`: refreshToken()

**Shared:** Types, DTOs, constants (Day, Month with German translations), ExpandedEvent type, and date utilities defined and exported.

**Frontend:**
- Tab navigation (Chat, Calendar) implemented with basic UI
- Calendar screen fully functional:
  - Month navigation with grid display and Ionicons (chevron-back/forward)
  - MonthSelector dropdown with infinite scroll (dynamically loads months, lazy-loaded when modal opens, cleared on close for memory efficiency)
  - Events loaded from API via EventService.getByDateRange()
  - Orange dot indicator for days with events
  - Tap-to-open modal overlay showing EventCards for selected day
  - Supports events from adjacent months visible in grid
  - Uses `useFocusEffect` for automatic reload on tab focus
- Chat screen fully functional with FlashList, message sending, and event confirm/reject
  - Messages persisted to database via ChatService and loaded on mount
  - Tracks conversationId for message continuity across sessions
  - ChatStore with addMessages() for bulk loading, chatMessageToMessageData() helper
  - KeyboardAvoidingView for proper keyboard handling (iOS padding, Android height)
  - Auto-scroll to end on new messages and keyboard show
  - keyboardDismissMode="interactive" and keyboardShouldPersistTaps="handled"
- `ApiClient`: get(), post(), put(), delete() implemented with request/response logging
- `EventService`: getAll(), getById(), getByDateRange(), create(), update(), delete() - fully implemented
- `ChatService`: sendMessage(), confirmEvent(), rejectEvent(), getConversations(), getConversation() - fully implemented with cursor pagination
- `EventCardBase`: Shared base component with event layout (header, date/time/recurring icons, description) - used by both EventCard and ProposedEventCard
- `EventCard`: Uses EventCardBase + edit/delete buttons for calendar display
- `ProposedEventCard`: Uses EventCardBase + confirm/reject buttons for chat proposals (supports create/update/delete actions)
- `Themes.tsx`: Centralized color definitions including textPrimary, borderPrimary, eventIndicator, secondaryBg
- `EventsStore`: Zustand store with setEvents(), addEvent(), updateEvent(), deleteEvent() - stores ExpandedEvent[]
- `ChatStore`: Zustand store with addMessage(), addMessages(), updateMessage(), clearMessages() - loads from server on mount and persists across tab switches
- Auth screens (Login, Register), Event Detail, and Note screens exist as skeletons
- AuthStore defined with `throw new Error('Not implemented')`

## Documentation

Detailed architecture diagrams are in `docs/`:
- `api-routes.md` - API endpoint overview (German)
- `technisches_brainstorm.tex` - Technical concept document (German)
- `architecture-class-diagram.puml` - Backend class diagram
- `frontend-class-diagram.puml` - Frontend class diagram
- `component-diagram.puml` - System component overview