Supported Backends

LSP backends compatible with typemux-cc

Overview

typemux-cc supports three Python LSP backends. You can switch between them using the TYPEMUX_CC_BACKEND environment variable.

Available Backends

Pyright is the default backend if TYPEMUX_CC_BACKEND is not set.

Backend	Command	Status
pyright	pyright-langserver --stdio	✅ Stable (default)
ty	ty server	🧪 Experimental (verified)
pyrefly	pyrefly lsp	🧪 Experimental (verified)

Installation Instructions

Pyright (Recommended)

Pyright is the default and most stable backend.

# Via npm (recommended)
npm install -g pyright

# Via pip (alternative)
pip install pyright

Verify installation:

which pyright-langserver

ty (Experimental)

ty is a new Python type checker by the creators of uv (Astral).

# Via pip
pip install ty

# Via uvx
uvx ty

Verify installation:

which ty

ty is experimental but verified to work with typemux-cc.

pyrefly (Experimental)

pyrefly is Meta’s Python type checker.

# Via pip
pip install pyrefly

Verify installation:

which pyrefly

pyrefly is experimental but verified to work with typemux-cc.

Backend Selection

Via Configuration File

Create or edit ~/.config/typemux-cc/config:

mkdir -p ~/.config/typemux-cc
cat > ~/.config/typemux-cc/config << 'EOF'
# Select backend (pyright, ty, or pyrefly)
export TYPEMUX_CC_BACKEND="pyright"
EOF

Via Environment Variable

# One-time use
TYPEMUX_CC_BACKEND=ty ./target/release/typemux-cc

# For current session
export TYPEMUX_CC_BACKEND=ty

Via CLI Flag

./target/release/typemux-cc --backend ty

Backend-Specific Notes

Pyright

• Most mature: Production-ready with extensive type checking features
• Default choice: Automatically selected if TYPEMUX_CC_BACKEND is not set
• Installation: Available via both npm and pip
• Best for: General Python development, maximum compatibility

ty

• Performance focused: Built by Astral (creators of uv and ruff)
• Experimental: Newer project, still under active development
• Best for: Users who want cutting-edge performance
• Note: Some advanced type features may not be fully supported yet

pyrefly

• Meta-backed: Developed by Facebook/Meta
• Experimental: Less widely adopted than pyright
• Best for: Projects already using Meta’s Python tooling
• Note: Smaller ecosystem and community compared to pyright

Common Issues

Make sure the backend command is available in your PATH before starting typemux-cc. Use which <command> to verify.

Backend not found

# Check if backend is in PATH
which pyright-langserver  # for pyright
which ty                  # for ty
which pyrefly            # for pyrefly

# Check typemux-cc logs
tail -100 /tmp/typemux-cc.log

Wrong backend being used

Verify your configuration:

# Check environment variable
echo $TYPEMUX_CC_BACKEND

# Check config file
cat ~/.config/typemux-cc/config

Backend crashes

Enable detailed logging:

RUST_LOG=trace TYPEMUX_CC_LOG_FILE=/tmp/typemux-cc.log

Then check the logs for backend-specific error messages.