Watchtower DAP Windows Debugging

Windows-native MCP ⇄ DAP bridge enabling step-through debugging for C#, Node/TS, Python, and Dart

Overview

Watchtower is a Model Context Protocol (MCP) server that provides unified debugging capabilities across multiple programming languages on Windows. It acts as a bridge between MCP clients and various debug adapters, offering a consistent interface for debugging workflows.

Related MCP server: DebugPilot

Features

• Windows-Native: Optimized for Windows 10/11 with Windows-specific adapter detection

• Multi-Language Support: C# (vsdbg/netcoredbg), Node.js/TypeScript (vscode-js-debug), Python (debugpy), Dart/Flutter (DAP adapter)

• Unified MCP Interface: All 13 required DAP tools exposed through MCP protocol

• Launch & Attach: Support for both launching new processes and attaching to running processes

• Deterministic Debug Loop: Cursor-based event polling with pagination

• Security-By-Default: Environment variables and command-line arguments redacted in logs

• High Performance: Time to First Break ≤ 1000ms, Step operations p95 ≤ 200ms

• Observability Foundation: OpenTelemetry metrics and structured logging

Architecture

┌─────────────────┐    ┌─────────────────┐    ┌─────────────────┐
│   MCP Client    │───▶│  Watchtower     │───▶│ Debug Adapters  │
│   (Claude Code) │    │   Server        │    │  (DAP Clients) │
└─────────────────┘    └─────────────────┘    └─────────────────┘
                              │
                              ▼
                       ┌─────────────────┐
                       │  Event Ring     │
                       │  Buffer        │
                       └─────────────────┘

Development Status

• Specification: ✅ Complete

• Implementation Plan: ✅ Complete

• Tasks & Checklists: ✅ Complete

• Analysis: ✅ Complete (9.2/10 rating)

• Implementation: 🚧 Phase 1 - Setup

Quick Start (Alpha)

# Install dependencies
npm install

# Build the project
npm run build

# Run the MCP server
npm start

# Or run directly
npx dist/watchtower serve

Alpha Release Goals

• Node.js debugging with breakpoints and stepping

• Python debugging with breakpoints and stepping

• Basic MCP tool coverage (dap.start, dap.setBreakpoints, etc.)

• Integration with Claude Code MCP configuration

Requirements

• Windows 10/11

• Node.js 22 LTS

• Target language debug adapters (auto-detected)

Constitution

This project operates under the Watchtower Constitution with principles including:

• Windows-Native Focus: No Linux/WSL support in v1

• DAP as Single Source of Truth: All debugging through DAP adapters

• Minimal MCP Tool Surface: Only essential tools exposed

• Security-By-Default: Redaction and validation active by default

• Observability Foundation: Comprehensive metrics and logging

Project Structure

mcp-watchtower/
├── src/                    # TypeScript source code
│   ├── adapters/           # Language-specific adapters
│   ├── server/             # MCP server implementation
│   ├── transport/          # DAP transport layer
│   ├── tools/              # MCP tool implementations
│   └── types/              # TypeScript type definitions
├── tests/                  # Test files
│   ├── contract/           # Contract tests
│   ├── integration/        # Integration tests
│   └── unit/               # Unit tests
├── docs/                   # Documentation
├── specs/                  # Specification documents
└── dist/                   # Built JavaScript artifacts

Quality Gates

The project includes comprehensive quality checklists for:

• ✅ Requirements Validation: 42 functional requirements validated

• ✅ Quality Gates: 60 validation items across all dimensions

• ✅ Release Readiness: 65 items tracking Alpha/Beta/GA milestones

Implementation Phases

1. Setup: Project initialization and tooling

2. Foundational: Core infrastructure (transport, sessions, adapters)

3. User Story 1: Node.js + Python debugging (Alpha)

4. User Story 2: Multi-language support (Beta)

5. User Story 3: Remote attachment (Beta)

6. Polish: Documentation, samples, CI, hardening (GA)

Contributing

This project follows the implementation tasks and quality guidelines.

License

See LICENSE file.