Installation

emend wheels include the compiled emend_core Rust extension — there is no separate binary package to install.

Using uv (standard Python)

uv tool install emend

Using pip

pip install emend

MCP server

To use emend as an MCP server for LLM-based clients, install the optional mcp extra:

pip install emend[mcp]

Then start the server:

emend mcp                              # stdio transport (default)
emend mcp --transport sse --port 8080  # SSE transport

The optional extra installs MCP SDK v2 (mcp>=2.0).

Adding emend to Claude Code

The quickest way to connect emend to Claude Code is the claude mcp add CLI:

# Add for the current project (default scope: local)
claude mcp add --transport stdio emend -- emend mcp

# Or share with your team via .mcp.json (project scope)
claude mcp add --transport stdio --scope project emend -- emend mcp

If you installed with uv tool install, make sure the emend binary is on your PATH, or use uvx:

claude mcp add --transport stdio emend -- uvx emend mcp

You can also configure it by editing JSON directly:

claude mcp add-json emend '{"type":"stdio","command":"emend","args":["mcp"]}'

For a team-shared setup, add a .mcp.json file to your project root (and commit it to version control):

{
  "mcpServers": {
    "emend": {
      "type": "stdio",
      "command": "emend",
      "args": ["mcp"]
    }
  }
}

Verify the server is connected:

claude mcp list          # from the terminal

Or inside Claude Code, type /mcp to see all connected servers and their status.

Scopes. Claude Code has three MCP configuration scopes:

  • local (default) – private to you, current project only (stored in ~/.claude.json)

  • project – shared with the team via .mcp.json in the project root (committed to version control)

  • user – available to you across all projects (stored in ~/.claude.json)

Use --scope with claude mcp add to choose. See the Claude Code MCP documentation for full details on scopes, environment variables, and managed configurations.

Vim / Neovim plugin

emend ships with a Vim/Neovim plugin for interactive code search. It communicates with emend tool editor-server via JSON-RPC over stdio pipes, keeping the server warm for sub-5ms symbol lookups.

Install with vim-plug:

Plug 'lucaswiman/emend', { 'rtp': 'vim' }

Or for local development, point to your checkout:

Plug '~/src/emend', { 'rtp': 'vim' }
let g:emend_command = '~/src/emend/.venv/bin/emend'

After installing, use :Emend to open the search prompt. See vim/README.md and :help emend for full documentation.

Verifying installation

emend --help

Dependencies

emend uses the bundled emend_core Rust extension (built on tree-sitter) as its AST backend — all parsing, traversal, scope analysis, pattern matching, and transformation go through tree-sitter and Rust. The extension is GIL-free and optimized for parallel file scanning on free-threaded Python.

Runtime dependencies (all installed automatically):

  • Typer – CLI framework

  • Lark – Grammar-based parsing for selectors and patterns

  • PyYAML – YAML parsing for batch operations and lint rules

The emend_core extension (tree-sitter, rayon, PyO3) is compiled into the wheel and requires no separate installation.

Installing from source

Requires a Rust toolchain (rustup) and maturin.

git clone https://github.com/lucaswiman/emend
cd emend

# Create a free-threaded venv, compile the Rust extension, install dev deps
make venv

Or manually:

uv venv .venv --python 3.13t
uv pip install maturin
.venv/bin/maturin develop -E dev