FS-Git MCP Server

A Git-enforced filesystem MCP server that integrates git with filesystem operations, enforcing commits on writes, providing reads with history, and supporting staged branching.

Features

• Direct Mode: Write and commit in one call with templated messages.

• Staged Mode: Open ephemeral branch, stage edits, preview, then merge/rebase or abort.

• Reader Subagent: Intent-directed extraction and summarization.

• Integrated Tools: Wraps file_system, text_replace, code_diff with git semantics.

• Safety: Path traversal protection, git safe.directory, dirty tree guards.

Installation

uv venv && uv pip install -e .[dev]
pre-commit install

MCP Server Usage

Running the MCP Server

The fs-git MCP server can be run in two ways:

Option 1: Using the CLI command

# For Claude Desktop and MCP Inspector (stdio transport)
fs-git serve

# For development/testing (TCP transport)  
fs-git serve --transport tcp --port 8080

Option 2: Using the direct MCP server command

# stdio mode (default, for Claude Desktop)
fs-git-mcp

# TCP mode for development
fs-git-mcp --transport tcp --port 8080

Option 3: Using uvx (no installation required)

# Run directly without installation
uvx fs-git-mcp

# Or with the CLI
uvx --from . fs-git serve

Claude Desktop Configuration

Add this to your Claude Desktop configuration (~/.claude/config.json):

{
  "mcpServers": {
    "fs-git": {
      "command": "uvx",
      "args": ["fs-git-mcp"]
    }
  }
}

Or if installed locally:

{
  "mcpServers": {
    "fs-git": {
      "command": "fs-git-mcp"
    }
  }
}

Testing with MCP Inspector

# Install MCP Inspector
npm install -g @modelcontextprotocol/inspector

# Test the server
npx @modelcontextprotocol/inspector fs-git-mcp

Available MCP Tools

The MCP server exposes these tool namespaces:

• git_fs: write_and_commit, read_with_history, start_staged, staged_write, staged_preview, finalize_staged, abort_staged

• fs_reader: extract, answer_about_file

• fs_text_replace: replace_and_commit

• fs_code_diff: preview_diff

• fs_io: read_file, stat_file, list_dir, make_dir

Path Authorization

FS-Git supports configurable path authorization for security. You can restrict which paths can be accessed using CLI parameters or environment variables.

CLI Parameters

# Allow only specific paths
fs-git write --repo <root> --path src/utils.py \
  --allow-paths "src/**,docs/**" \
  --deny-paths "!src/secrets/**,!**/node_modules/**" \
  --file - --subject "[{op}] {path} – {summary}" \
  --op "add" --summary "utility functions" <<'EOF'
def helper():
    return "utility"
EOF

Environment Variables

Set path patterns via environment variables for global configuration:

# Set allowed paths (comma-separated)
export FS_GIT_ALLOWED_PATHS="src/**,docs/**,*.md"

# Set denied paths (comma-separated, with ! prefix)
export FS_GIT_DENIED_PATHS="!**/node_modules/**,!**/.git/**,!src/secrets/**"

# Now all fs-git commands will use these patterns
fs-git write --repo <root> --path src/app.py --file - --subject "Add app" <<'EOF'
print("Hello World")
EOF

Pattern Support

• Glob patterns: src/**, docs/**/*.md, *.txt

• Regex patterns: r".*\.py$", r".*\.js$"

• Deny patterns: Prefix with ! (e.g., !**/node_modules/**)

• Absolute paths: /etc/hosts, /usr/local/bin/

• Relative paths: src/, ./docs/

Priority: CLI parameters override environment variables.

Quick Start

1. Initialize a repo:

   fs-git init <repo_root>

2. Direct write:

   fs-git write --repo <root> --path <p> --file <in> \
     --subject "[{op}] {path} – {summary}" --op "edit" --summary "update"

3. Staged flow:

   sid=$(fs-git staged start --repo <root> --ticket T-123)
   fs-git staged write --session "$sid" --path <p> --file <in> --summary "..."
   fs-git staged preview --session "$sid"
   fs-git staged finalize --session "$sid" --strategy rebase-merge

4. Reader extract:

   fs-git reader extract --repo <root> --path <p> --query "foo.*bar" --regex

Demo

Quick Demo

Run the basic demo script:

make demo

Comprehensive Demo

Run the complete copy-paste demo that showcases all features:

# From the fs-git project root
bash repos/fs-git/scripts/comprehensive_demo.sh

This comprehensive demo includes:

• Installation and setup

• Basic direct write operations with git commits

• Staged workflow with ephemeral branches

• Text replacement and patch application

• Path authorization with allowed/denied patterns

• Environment variable configuration

• MCP server testing

• Claude Desktop integration examples

Development

• Tests: make test

• Lint: make fmt && make lint

• E2E: make test-e2e

Architecture

See ARCHITECTURE.md for module details.

Tooling

See TOOLING.md for MCP schema and integrations.

Troubleshooting

Common Issues

• Import Errors: Ensure mcp_server is in PYTHONPATH or installed with uv pip install -e .

• Git Safe Directory: If git complains about unsafe repo, run git config --global --add safe.directory <repo_root>

• Path Authorization Denied: Check your FS_GIT_ALLOWED_PATHS and FS_GIT_DENIED_PATHS env vars or CLI flags.

• Staged Session Not Found: Sessions are stored in ~/.fs_git_sessions. Clear if corrupted.

• MCP Inspector Connection: Use fs-git serve for stdio mode with Inspector. For TCP, use --transport tcp.

• Subprocess Python Errors: Tests use sys.executable to match your Python environment.

Logs

• Server logs: Check server.log or stderr.

• Git logs: Use git log --oneline -10 in repo.

Debug Mode

Run with debug:

FS_GIT_DEBUG=true fs-git serve --transport tcp

Changelog

See CHANGELOG.md.