Semamerge MCP server

SemaMerge

<!-- mcp-name: io.github.vineethwilson15/semamerge -->

An MCP (Model Context Protocol) server that detects semantic merge conflicts between Git branches using AST-level analysis.

When two branches change code in ways that Git merges cleanly but are functionally incompatible, SemaMerge catches it before the merge breaks your app.

What It Detects

Installation

npx semamerge

Or install globally:

npm install -g semamerge

Or clone and build from source:

git clone https://github.com/vineethwilson15/semamerge.git
cd semamerge
npm install
npm run build

MCP Tools

checkmergesafety

Quick pre-merge check. Returns a risk score (safe/warning/danger).

{
  "repoPath": "/path/to/repo",
  "sourceBranch": "feature-x",
  "targetBranch": "main"
}

analyze_branches

Deep analysis with per-file breakdown of all semantic conflicts.

{
  "repoPath": "/path/to/repo",
  "branchA": "feature-x",
  "branchB": "feature-y",
  "baseBranch": "main"
}

listsemanticchanges

Lists all semantic changes on a branch (functions, exports, types, etc.).

{
  "repoPath": "/path/to/repo",
  "branch": "feature-x",
  "baseBranch": "main"
}

analyzefilepair

Deep-dive into a specific file's semantic diff between two branches.

{
  "repoPath": "/path/to/repo",
  "filePath": "src/utils.ts",
  "branchA": "feature-x",
  "branchB": "main"
}

Configuration

VS Code (Copilot)

Add to your VS Code settings.json:

{
  "mcp": {
    "servers": {
      "semamerge": {
        "command": "node",
        "args": ["/path/to/semamerge/dist/index.js"]
      }
    }
  }
}

Claude Desktop

Add to claudedesktopconfig.json:

{
  "mcpServers": {
    "semamerge": {
      "command": "node",
      "args": ["/path/to/semamerge/dist/index.js"]
    }
  }
}

Supported Languages

• TypeScript / JavaScript (.ts, .tsx, .js, .jsx, .mjs, .cjs)
• Python support planned

How It Works

1. Git layer — Reads file content from branches without checkout using git show
2. AST parsing — Parses source code with tree-sitter (WASM) into syntax trees
3. Semantic extraction — Walks ASTs to extract function signatures, types, exports, imports, enums
4. Three-way comparison — Computes semantic diffs from common ancestor to each branch
5. Conflict detection — Cross-references changes to find incompatibilities

Development

npm run build    # Compile TypeScript
npm run dev      # Watch mode
npm test         # Run tests

License

MIT