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 # City Builder - Project Summary
 ## Project Overview
 A fully functional multiplayer city building game inspired by Transport Tycoon's visual style, built with FastAPI backend and Three.js frontend.
 ## What Was Built
 ### Backend (Python/FastAPI)
 All backend files are in the `server/` directory:
 . **main.py** - FastAPI application entry point
    - WebSocket endpoint for multiplayer
    - Static file serving
    - Game loop for economy ticks and persistence
 . **websocket_manager.py** - WebSocket connection management
    - Player connection/disconnection
    - Message broadcasting
    - Cursor synchronization
 . **models.py** - Data models
    - 13 building types with unique properties
    - Player model with economy tracking
    - Building configurations with costs and benefits
 . **game_state.py** - Game state management
    - Building placement/removal logic
    - Road network connectivity (flood fill algorithm)
    - Zone size calculation for economy bonuses
 . **economy.py** - Economy engine
    - Tick-based economy processing
    - Offline player support (10% power)
    - Connectivity-based income bonuses
 . **database.py** - SQLite persistence
    - Auto-save every 10 seconds
    - Player data persistence
    - Building state persistence
 ### Frontend (JavaScript/Three.js)
 All frontend files are in the `static/` directory:
 . **App.js** - Main application controller
    - Coordinates all systems
    - Handles game state updates
    - Player action processing
 . **WebSocketClient.js** - Real-time communication
    - WebSocket connection management
    - Message handling and routing
    - Auto-reconnect logic
 . **GameRenderer.js** - Three.js 3D rendering
    - Orthographic camera (Transport Tycoon style)
    - Building mesh creation
    - Tile highlighting
    - Player cursor rendering
 . **InputHandler.js** - User input processing
    - Mouse controls (left/right click, wheel)
    - Keyboard shortcuts
    - Camera pan and zoom
    - Tile coordinate conversion
 . **UIManager.js** - UI component coordination
    - Component initialization
    - State updates
    - Event routing
 ### UI Components (Web Components)
 All components extend HTMLElement:
 . **LoginScreen.js** - Nickname entry screen
 . **StatsDisplay.js** - Money and population display
 . **BuildingToolbox.js** - Building selection menu
 . **ChatBox.js** - IRC-style chat interface
 . **ContextMenu.js** - Right-click building menu
 ### Configuration Files
 - **requirements.txt** - Python dependencies
 - **.gitignore** - Git ignore rules
 - **run.py** - Convenient startup script
 - **README.md** - Complete documentation
 ## Key Features Implemented
 ### Core Gameplay
 - ✅ 13 unique building types (houses, shops, factories, infrastructure, special)
 - ✅ Realistic building costs ($500 - $100,000)
 - ✅ Economic system with income/expenses per tick
 - ✅ Population management
 - ✅ Building requirements (population, power)
 ### Road System
 - ✅ Road construction ($500 per tile)
 - ✅ Connectivity algorithm (flood fill)
 - ✅ Economy bonuses based on network size (5% per road)
 - ✅ Multiple disconnected zones support
 ### Multiplayer
 - ✅ Real-time WebSocket communication
 - ✅ Live cursor synchronization
 - ✅ Building synchronization across clients
 - ✅ Player-specific colors
 - ✅ Join/leave notifications
 - ✅ IRC-style chat system
 ### Persistence
 - ✅ SQLite database storage
 - ✅ Auto-save every 10 seconds
 - ✅ Nickname-based login (no passwords)
 - ✅ Offline economy processing (10%)
 - ✅ Session resumption
 ### User Interface
 - ✅ Login screen (Enter to submit)
 - ✅ Stats display (money, population)
 - ✅ Building toolbox with prices
 - ✅ Grayed out unaffordable options
 - ✅ Context menu (Edit/Delete)
 - ✅ Chat box with timestamps
 - ✅ No buttons - keyboard shortcuts
 ### Controls
 - ✅ Right mouse drag - Pan camera
 - ✅ Mouse wheel - Zoom in/out
 - ✅ Left click - Place building
 - ✅ Right click on building - Context menu
 - ✅ Enter - Confirm input
 - ✅ Escape - Cancel input
 - ✅ Tile highlighting on hover
 ### Rendering Optimization
 - ✅ Viewport culling (only render visible tiles)
 - ✅ Throttled cursor updates (100ms)
 - ✅ Efficient building mesh management
 - ✅ Three.js orthographic camera for performance
 ## Game Mechanics
 ### Building Types & Economics
 **Residential** (Provide Population)
 - Small House: -$50/tick, +10 pop
 - Medium House: -$120/tick, +25 pop
 - Large House: -$250/tick, +50 pop
 **Commercial** (Generate Income)
 - Small Shop: +$100/tick, -5 pop, needs 20 pop
 - Supermarket: +$300/tick, -15 pop, needs 50 pop
 - Mall: +$800/tick, -40 pop, needs 100 pop
 **Industrial** (Generate Income)
 - Small Factory: +$200/tick, -20 pop
 - Large Factory: +$500/tick, -50 pop
 **Infrastructure**
 - Road: Connects buildings, boosts economy
 - Park: -$20/tick, +5 pop
 - Plaza: -$40/tick, +10 pop
 **Special**
 - Town Hall: -$100/tick, +100 pop
 - Power Plant: -$500/tick, -30 pop, enables large buildings
 ### Economy Formula
 ```
 Building Income = Base Income × Connectivity Bonus
 Connectivity Bonus = 1.0 + (Road Network Size × 0.05)
 ```
 ### Offline Economy
 When a player is offline, their economy continues at 10% power:
 ```
 Offline Income = Base Income × 0.10
 ```
 ## Technical Specifications
 ### Server
 - **Framework**: FastAPI 0.118.0
 - **WebSocket**: Native FastAPI WebSocket support
 - **Database**: SQLite3 (built-in)
 - **Host**: 127.0.0.1:9901
 - **Game Tick**: Every 10 seconds
 - **Persistence**: Every 10 seconds
 ### Client
 - **Renderer**: Three.js r128
 - **View**: Orthographic camera (Transport Tycoon style)
 - **Architecture**: ES6 Modules
 - **Components**: Web Components (Custom Elements)
 - **No frameworks**: Pure vanilla JavaScript
 ### Communication Protocol
 All WebSocket messages are JSON with a `type` field:
 **Client → Server**
 - `cursor_move`: {x, y}
 - `place_building`: {building_type, x, y}
 - `remove_building`: {x, y}
 - `edit_building`: {x, y, name}
 - `chat`: {message, timestamp}
 **Server → Client**
 - `init`: Initial player and game state
 - `game_state_update`: Periodic full state sync
 - `building_placed`: Building added
 - `building_removed`: Building removed
 - `building_updated`: Building name changed
 - `cursor_move`: Player cursor moved
 - `player_joined`: Player connected
 - `player_left`: Player disconnected
 - `chat`: Chat message
 - `error`: Error message
 ## Project Structure
 ```
 city-builder/
 ├── server/              # Backend Python code
 │   ├── __init__.py
 │   ├── main.py
 │   ├── websocket_manager.py
 │   ├── game_state.py
 │   ├── economy.py
 │   ├── database.py
 │   └── models.py
 ├── static/              # Frontend code
 │   ├── index.html
 │   ├── css/
 │   │   └── style.css
 │   └── js/
 │       ├── App.js
 │       ├── WebSocketClient.js
 │       ├── GameRenderer.js
 │       ├── InputHandler.js
 │       ├── UIManager.js
 │       └── components/
 │           ├── LoginScreen.js
 │           ├── StatsDisplay.js
 │           ├── BuildingToolbox.js
 │           ├── ChatBox.js
 │           └── ContextMenu.js
 ├── data/                # SQLite database (auto-created)
 │   └── game.db
 ├── requirements.txt
 ├── .gitignore
 ├── run.py
 ├── README.md
 └── PROJECT_SUMMARY.md
 ```
 ## Development Approach
 The project follows modern best practices:
 . **Separation of Concerns**: Clear separation between backend, frontend, and UI
 . **Component Architecture**: Each component is self-contained
 . **ES6 Modules**: Modern JavaScript module system
 . **Web Components**: Custom HTML elements for reusability
 . **Real-time Communication**: WebSocket for instant updates
 . **Optimistic Updates**: UI updates immediately, server validates
 . **Error Handling**: Graceful error messages to users
 . **Performance**: Only render what's visible
 . **Persistence**: Auto-save prevents data loss
 . **Multiplayer**: True multiplayer with shared game state
 ## How to Run
 ```bash
 # Install dependencies
 python -m venv .venv
 source .venv/bin/activate
 pip install -r requirements.txt
 # Start server
 python run.py
 # Open in browser
 http://127.0.0.1:9901
 ```
 ## Testing the Game
 . Open browser to http://127.0.0.1:9901
 . Enter a nickname (press Enter)
 . Try building:
    - Click "Small House" in the toolbox
    - Click on the map to place it
    - Build more houses to increase population
    - Build roads to connect buildings
    - Build shops once you have enough population
 . Try multiplayer:
    - Open another browser tab/window
    - Enter a different nickname
    - See both players' cursors and buildings
 . Try chat:
    - Type in the chat box at the bottom
    - Press Enter to send
 . Try right-click menu:
    - Right-click your own building
    - Choose "Edit Name" or "Delete"
 ## Completion Status
 **ALL REQUIREMENTS MET ✓**
 Every feature from the original specification has been implemented:
 - Transport Tycoon visual style with Three.js
 - Real-time multiplayer via WebSocket
 - 10+ building types with economic gameplay
 - Road connectivity system
 - Player-specific colors
 - Live cursor tracking
 - IRC-style chat
 - Nickname-based login
 - Offline economy (10% power)
 - Context menus
 - No-button inputs (Enter/Escape)
 - Performance optimizations
 - SQLite persistence
 The game is fully playable and ready for deployment!