Repo Therapist 🛋️

Your codebase explains itself under pressure

Repo Therapist is an MCP (Model Context Protocol) server that turns any repository into queryable, explainable knowledge. Ask questions about your codebase through Cursor and get structured, insightful answers.

What it does

You ask Cursor things like:

• "Why is this service structured like this?"
• "What will break if I remove this?"
• "Which parts of this repo scare you?"

Behind the scenes, Repo Therapist:

• Reads your repo structure and files
• Analyzes git history and commit patterns
• Correlates code with change frequency
• Identifies complexity hotspots and risks

Available Tools

Ground Truth: The Snapshot

When you run analyze_repo, Repo Therapist creates a static snapshot - the authoritative source of truth about your repository. This snapshot includes:

{
  "files": [...],           // Every file with path, language, line count
  "languages": {...},       // Language breakdown with percentages
  "entryPoints": [...],     // Detected entry points with confidence levels
  "configs": {...},         // Parsed package.json, tsconfig, Dockerfile, CI configs
  "directories": [...]      // Directory structure with inferred purposes
}

Why this matters: LLMs must cite this snapshot data, not guess. When you ask "What languages does this repo use?", the answer comes from the snapshot - not from the LLM making assumptions.

Use get_snapshot to retrieve specific sections:

• get_snapshot(section: "files") - All files with metadata
• get_snapshot(section: "languages") - Language statistics
• get_snapshot(section: "entryPoints") - Detected entry points
• get_snapshot(section: "configs") - Parsed configuration files
• get_snapshot(section: "directories") - Directory structure
• get_snapshot() - Summary of everything

Git Historian: The Time Dimension

The Git Historian analyzes commit history to explain WHY code is the way it is. This is where it stops being cute.

{
  "fileChurn": { "auth.ts": { "totalCommits": 47, "churnScore": 85 } },
  "authors": { "auth.ts": ["alice", "bob", "charlie"] },
  "fragileFiles": [{ "path": "auth.ts", "reasons": ["high-churn", "many-authors"] }],
  "hotPaths": [...],
  "stableCore": [...]
}

This lets you answer:

• "Why is this weird?" → "Because it's been rewritten 12 times in 6 months."
• "Who owns this file?" → "Disputed - 4 people have modified it, none with >30%."
• "What should I be careful with?" → "These 5 files are fragile and bug-prone."

Use get_history to retrieve specific aspects:

• get_history(section: "churn") - File change frequency and volatility
• get_history(section: "authors") - Contributor statistics
• get_history(section: "fragile") - Files likely to cause problems
• get_history(section: "hotPaths") - Hot paths vs stable core
• get_history(section: "timeline") - Key events and commit patterns
• get_history(section: "ownership") - Who owns what
• get_history() - Summary of everything

Use why_is_this_weird for specific file analysis:

Use why_is_this_weird on "src/auth/login.ts"

Returns a detailed explanation with citations:

# Why is "src/auth/login.ts" the way it is?

## Change History
- Total commits: 47
- Authors: 5 (alice, bob, charlie, dave, eve)
- Churn score: 85 ⚠️ HIGH

## 🔍 Why It's Unusual
**Heavily modified:** This file has been changed 47 times...
**Many hands:** 5 different people have modified this file...

Setup

1. Install dependencies

cd repo-therapist
npm install

2. Build the project

npm run build

3. Add to Cursor

Open Cursor Settings → MCP → Add new MCP server:

{
  "mcpServers": {
    "repo-therapist": {
      "command": "node",
      "args": ["/FULL/PATH/TO/repo-therapist/dist/index.js"]
    }
  }
}

Important: Replace /FULL/PATH/TO/ with the actual absolute path to your repo-therapist folder.

Example:

{
  "mcpServers": {
    "repo-therapist": {
      "command": "node",
      "args": ["/Users/saar/Projects/private/repo-therapist/dist/index.js"]
    }
  }
}

4. Restart Cursor

After adding the MCP config, restart Cursor for changes to take effect.

FAQ

Do I need to run repo-therapist separately?

No. Cursor automatically starts and manages the MCP server for you. When you add the config to Cursor's MCP settings, Cursor will:

• Start the node dist/index.js process when needed
• Keep it running in the background
• Communicate with it via stdio (standard input/output)

You just need to build once (npm run build), add the config, and restart Cursor. That's it.

Where do I ask questions?

In the normal Cursor chat (Cmd+L or the chat panel). The difference is how you ask:

• Without MCP: "What does this repo do?" → Cursor uses its built-in tools
• With Repo Therapist: "Use analyze_repo on /path/to/repo" → Cursor calls the MCP tool

You explicitly tell Cursor to use the repo-therapist tools. Cursor sees them as additional capabilities it can use.

What's the difference vs normal Cursor chat?

The key difference: Repo Therapist does structured analysis upfront and stores it, so questions like "which files change most often?" or "what are the risks?" can be answered from pre-computed data rather than Cursor having to figure it out each time.

Think of it as: Cursor is smart but reactive. Repo Therapist gives it a "briefing document" about your codebase that it can reference.

Usage

Once configured, you can use Repo Therapist in Cursor chat:

Step 1: Analyze a repo

First, analyze the repository you want to explore:

Use analyze_repo to analyze /path/to/some/repo

Step 2: Ask questions

Now you can ask questions:

Use ask_repo to answer: "What does this repo do?"

Use ask_repo to answer: "Which parts of this repo scare you?"

Use ask_repo to answer: "What will break if I remove the auth module?"

Step 3: Get reports

Get a summary:

Use repo_summary to show me an overview

Get a risk assessment:

Use risk_report to identify potential issues

Example Questions

• "What does this repo do?"
• "How is the code structured?"
• "What tech stack is being used?"
• "Show me the dependencies"
• "Which files are the largest?"
• "What files change most often?"
• "Who are the contributors?"
• "What are the recent commits?"
• "Which parts scare you?"
• "What will break if I change X?"

Development

Run in development mode

npm run dev

Build for production

npm run build

Run tests

npm test              # Run all tests
npm run test:watch    # Run tests in watch mode
npm run test:coverage # Run tests with coverage report

Testing Guidelines

Note: Always add unit tests when implementing new features.

Tests are located in tests/ and use Vitest. The test structure mirrors the source:

tests/
├── fixtures/           # Test utilities and mock repos
│   └── setup.ts        # Helper functions for creating test repos
├── scanner/            # Scanner module tests
├── historian/          # Historian module tests
├── tools/              # Tool tests
└── cache.test.ts       # Cache tests

When adding a new feature:

1. Create tests in the appropriate tests/ subdirectory
2. Use createTestRepo() from fixtures/setup.ts for git-related tests
3. Clean up test repos with cleanupTestRepo() in afterAll
4. Run npm test to verify all tests pass before committing

Project structure

repo-therapist/
├── src/
│   ├── index.ts              # MCP server entry point
│   ├── cache.ts              # In-memory repo cache
│   ├── types.ts              # TypeScript interfaces
│   ├── scanner/              # Static snapshot engine (Step 2)
│   │   ├── index.ts          # Scanner exports
│   │   ├── types.ts          # Snapshot type definitions
│   │   └── scan-repo.ts      # Repository scanner
│   ├── historian/            # Git history analyzer (Step 3)
│   │   ├── index.ts          # Historian exports
│   │   ├── types.ts          # History type definitions
│   │   └── analyze-history.ts # Git history analysis
│   └── tools/
│       ├── analyze-repo.ts   # Repository analyzer (orchestrates all)
│       ├── get-snapshot.ts   # Snapshot retrieval (ground truth)
│       ├── get-history.ts    # History retrieval (time dimension)
│       ├── ask-repo.ts       # Question answering
│       ├── repo-summary.ts   # Summary generator
│       └── risk-report.ts    # Risk assessment
├── tests/                    # Unit tests
│   ├── fixtures/             # Test utilities
│   ├── scanner/              # Scanner tests
│   ├── historian/            # Historian tests
│   └── tools/                # Tool tests
├── package.json
├── tsconfig.json
├── vitest.config.ts          # Test configuration
└── README.md

Tech Stack

• TypeScript - Type-safe codebase
• @modelcontextprotocol/sdk - MCP server implementation
• simple-git - Git history analysis
• ts-morph - TypeScript/JavaScript AST parsing (planned)
• glob - File pattern matching

Roadmap

• AST-based code analysis with ts-morph
• Persist analysis to JSON/SQLite
• Dependency graph visualization
• Security vulnerability detection
• Test coverage analysis
• Custom question handlers

License

MIT