Terminal Control MCP

# Terminal Control MCP - Product Requirements Document ## Overview The Terminal Control MCP is a Model Context Protocol server that enables AI agents to interact with and analyze terminal-based Text User Interface (TUI) applications. This tool bridges the gap between AI agents (which lack TTY access) and terminal applications, for example those built with frameworks like Ratatui in Rust. ## Problem Statement AI agents and language models cannot directly interact with terminal-based applications because they lack TTY (teletypewriter) access. This limitation prevents them from: - Testing and debugging TUI applications - Analyzing user interactions with terminal programs - Automating terminal-based workflows - Providing intelligent assistance for command-line tools - Understanding the visual state of terminal applications ## Solution The Terminal Control MCP server provides a standardized interface for AI agents to: 1. **Launch Terminal Applications**: Execute arbitrary terminal commands and TUI programs 2. **Interact with Applications**: Send keyboard input, mouse events, and control sequences 3. **Capture Screen State**: Take visual snapshots of the terminal screen 4. **Analyze Content**: Extract text content, cursor position, and application state 5. **Automate Workflows**: Chain multiple interactions to complete complex tasks ## Key Features ### Core Functionality #### 1. Terminal Session Management - Create and manage multiple isolated terminal sessions - Support for different shell environments (bash, zsh, fish, etc.) - Session persistence and cleanup - Environment variable configuration #### 2. Application Control - Launch any terminal command or TUI application - Send keyboard input (including special keys, control sequences) - Handle mouse events and interactions - Support for terminal resizing and configuration #### 3. Screen Capture & Analysis - PNG screenshot capture using ImageMagick import - Visual terminal state as actual images - Text extraction from terminal content (future enhancement) - Color and styling preservation in screenshots - Visual diff detection between states #### 4. State Management - Track application state changes - Maintain interaction history - Support for rollback/checkpoint functionality - Session recording and playback ### MCP Integration #### Tools Provided - `terminal_launch`: Start a new terminal session with specified command - `terminal_input`: Send keyboard input to active session - `terminal_capture`: Take a snapshot of current screen state - `terminal_resize`: Change terminal dimensions - `terminal_close`: Clean up and close session - `terminal_list`: List all active sessions - `terminal_history`: Get interaction history #### Resources Exposed - Session screenshots (as PNG files or base64 encoded images) - Terminal visual state (actual screenshots) - Application logs and error output - Session metadata and window information ## Target Use Cases ### Primary Use Cases 1. **TUI Application Testing** - Automated testing of Ratatui-based applications - UI regression testing for terminal applications - User interaction simulation and validation 2. **Terminal Workflow Automation** - Complex command-line task automation - Multi-step terminal operations - Integration testing across multiple CLI tools 3. **Debugging and Analysis** - Analyze user interaction patterns - Debug terminal application behavior - Performance analysis of TUI applications ## Technical Requirements ### Core Dependencies - **FastMCP**: MCP server framework - **Python 3.10+**: Runtime environment - **Xvfb**: Virtual X11 display server for headless operation - **xterm**: Terminal emulator for launching applications - **xdotool**: X11 automation tool for sending input and window management - **ImageMagick**: Screenshot capture with `import` command - **asyncio**: Asynchronous operation support ### Implementation Approach The system uses a **virtual X11 display approach** rather than direct TTY manipulation: 1. **Xvfb (X Virtual Framebuffer)**: Creates a virtual X11 display for headless operation 2. **xterm**: Launches terminal applications within the virtual display 3. **xdotool**: Sends keyboard input and manages window interactions 4. **ImageMagick import**: Captures actual PNG screenshots of the terminal This approach provides several advantages: - **True visual capture**: Real screenshots showing exactly what users would see - **Better application compatibility**: Works with any terminal application - **Robust input handling**: xdotool provides reliable keyboard/mouse simulation - **No TTY limitations**: Bypasses traditional TTY access restrictions ### Platform Support - **Primary**: Linux (Ubuntu, Debian, CentOS, etc.) - **Secondary**: macOS - **Future**: Windows (WSL2 support) ### Security Requirements - **Sandboxing**: Isolated terminal sessions - **Resource Limits**: CPU and memory constraints - **Access Control**: Configurable command restrictions - **Audit Logging**: All interactions logged for security ## Architecture ### System Components #### 1. MCP Server Core - FastMCP-based server implementation - Tool and resource registration - Client connection management - Error handling and logging #### 2. XTerm Session Manager - Virtual X11 display management (Xvfb) - xterm process spawning and control - Window ID tracking and management - Resource allocation and cleanup - Display state synchronization #### 3. Input/Output Handler - xdotool-based keyboard input processing - ImageMagick screenshot capture functionality - Window focus and interaction management - Event handling and queuing #### 4. Screen Analyzer - Visual content analysis - Text extraction with positioning - Change detection and diff generation - Cursor and selection tracking ### Data Flow 1. **Session Creation**: Agent requests new terminal session 2. **Command Execution**: Terminal manager spawns process 3. **Interaction Loop**: Agent sends input, receives screen updates 4. **State Capture**: Screen content captured and analyzed 5. **Response Generation**: Structured data returned to agent 6. **Session Cleanup**: Resources released when done ## Implementation Plan ### Phase 1: Foundation (Weeks 1-2) - Basic MCP server setup with FastMCP - Simple terminal session management - Basic input/output handling - Text-only screen capture ### Phase 2: Core Features (Weeks 3-4) - Advanced input handling (special keys, mouse) - Visual screen capture with imaging - Session persistence and management - Error handling and recovery ### Phase 3: Enhancement (Weeks 5-6) - Performance optimization - Advanced analysis features - Configuration and customization - Documentation and examples ### Phase 4: Testing & Polish (Weeks 7-8) - Comprehensive testing suite - Integration testing with common TUI apps - Performance benchmarking - Documentation completion ## Success Criteria ### Functional Requirements - ✅ Successfully launch and control terminal applications - ✅ Capture accurate screen representations - ✅ Handle complex keyboard input sequences - ✅ Support multiple concurrent sessions - ✅ Integrate seamlessly with MCP clients ### Quality Requirements - ✅ Comprehensive error handling - ✅ Clear documentation and examples - ✅ Substantial test coverage ### User Experience - ✅ Intuitive tool interface for developers - ✅ Reliable and predictable behavior - ✅ Clear error messages and debugging info - ✅ Minimal setup and configuration required ## Risk Assessment ### Technical Risks - **Terminal Compatibility**: Variations in terminal behavior - **Performance Scaling**: Resource usage with many sessions - **Platform Differences**: OS-specific implementation challenges ### Mitigation Strategies - Comprehensive testing across terminal types - Resource monitoring and limiting - Platform-specific optimization and testing - Fallback mechanisms for unsupported features ## Conclusion The Terminal Control MCP server will provide a crucial bridge between AI agents and terminal applications, enabling new possibilities for automation, testing, and analysis. By leveraging the MCP standard and focusing on robust terminal interaction capabilities, this tool will serve as a foundation for advanced terminal-based AI workflows.