Lightning Code Index (LCI)

Lightning fast code indexing for AI assistants

Lightning Code Index is a high-performance code search and indexing tool designed for AI assistants like Claude Desktop. It provides sub-millisecond search across your codebase using advanced indexing techniques including trigram indexing and tree-sitter AST parsing.

Features

• 🚀 Sub-millisecond search - Find code in <5ms
• 🌲 Tree-sitter AST parsing - Understand code structure for 10+ languages
• 🎯 Symbol resolution - Jump to definitions and references
• 🔍 Multi-modal search - Name, content, and structural search
• 📦 Multiple distribution methods - Go binaries, npm package, GitHub releases
• 🔌 MCP Server - Seamless integration with Claude Desktop

Quick Start

Option 1: NPX (Recommended, Cross-Platform)

Run without installation:

npx lightning-code-index version
npx lightning-code-index search "func" --root ./my-project

Option 2: npm (Global Install)

Install globally:

npm install -g lightning-code-index
lci version

Option 3: GitHub Releases

Download pre-built binaries from Releases:

• Linux (amd64, arm64)
• macOS (Intel, Apple Silicon universal)
• Windows (amd64)

# Linux
curl -L https://github.com/standardbeagle/lightning-code-index/releases/latest/download/lci-linux-amd64 -o lci
chmod +x lci

# macOS
curl -L https://github.com/standardbeagle/lightning-code-index/releases/latest/download/lci-darwin-universal -o lci
chmod +x lci

# Windows (PowerShell)
Invoke-WebRequest -Uri "https://github.com/standardbeagle/lightning-code-index/releases/latest/download/lci-windows-amd64.exe" -OutFile "lci.exe"

Option 4: Build from Source

Requires Go 1.21+:

git clone https://github.com/standardbeagle/lightning-code-index.git
cd lightning-code-index
make build
./lci version

Usage Examples

Command Line Interface

# Check version
lci version

# Index a project
lci index ./my-project

# Search for code
lci search "func" --root ./my-project

# Get symbol definition
lci definition "MyFunction" --root ./my-project

# Find references
lci references "MyFunction" --root ./my-project

# Help
lci --help

As MCP Server

LCI can run as an MCP (Model Context Protocol) server for integration with Claude Desktop:

Installation

Option 1: NPX (Simplest)

npm install -g @modelcontextprotocol/cli

Option 2: Build from Source

git clone https://github.com/standardbeagle/lightning-code-index.git
cd lightning-code-index
go install ./cmd/lci

Claude Desktop Configuration

Add to your Claude Desktop config file:

macOS/Linux:

{
  "mcpServers": {
    "lci": {
      "command": "npx",
      "args": ["lightning-code-index", "mcp"]
    }
  }
}

Windows:

{
  "mcpServers": {
    "lci": {
      "command": "cmd",
      "args": ["/c", "npx", "lightning-code-index", "mcp"]
    }
  }
}

Alternatively, if installed globally:

{
  "mcpServers": {
    "lci": {
      "command": "lci",
      "args": ["mcp"]
    }
  }
}

Configuration File Locations

Claude Desktop:

• macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
• Windows: %APPDATA%\Claude\claude_desktop_config.json
• Linux: ~/.config/claude/claude_desktop_config.json

VS Code/Cursor:

• Settings → Extensions → Claude → Configure Servers

MCP Configuration Example

Here's a simple configuration for indexing a project:

{
  "mcpServers": {
    "lci": {
      "command": "lci",
      "args": ["mcp"]
    }
  }
}

Auto-Detection: LCI automatically detects your project root by searching for common config files (.lci.kdl, package.json, go.mod, Cargo.toml, etc.) in the current directory and parent directories.

Project-Level Config: To customize indexing for a specific project, create a .lci.kdl file in your project root. If no config is found, LCI uses sensible defaults.

Example Workflow with Claude

Once configured, you can interact with Claude:

You: Can you search for all React components in my project?

Claude: I'll search for React components using LCI.

[Uses lci search "React" --root ./src to find components]

Found 15 React components in your project:
- src/components/Button.tsx
- src/components/Modal.tsx
- ...

Would you like me to analyze any specific component?

Supported Languages

LCI supports semantic parsing and indexing for:

• Go - Full AST support
• Python - Full AST support
• JavaScript/TypeScript - Full AST support
• Rust - Full AST support
• C/C++ - Full AST support
• C# - Full AST support
• Java - Full AST support
• PHP - Full AST support
• Zig - Full AST support

Build Targets

For building from source:

# Current platform
make build

# Cross-platform builds
make build-linux-amd64      # Linux x64
make build-linux-arm64      # Linux ARM64
make build-windows          # Windows x64
make build-darwin-universal # macOS (Intel + Apple Silicon)

# Build all
make build-release

See BUILD.md for detailed build instructions.

Development

Running Tests

make test           # All tests
make test-unit      # Unit tests only
make test-integration # Integration tests only
make test-race      # Race detector
make test-coverage  # Coverage report

Architecture

• Core Indexing: Go-based with tree-sitter for AST parsing
• Search Engine: Trigram index + symbol index for <5ms searches
• MCP Integration: Native MCP server implementation
• CLI Tool: Full-featured command-line interface

Performance

• Search latency: <5ms for typical projects
• Indexing speed: ~1000 files/second
• Memory usage: ~50MB for medium projects (<10k files)
• Binary size: ~30MB (includes all language parsers)

Troubleshooting

Binary not found

# If using npx
npx lightning-code-index <command>

# If installed globally but binary not in PATH
npm rebuild -g lightning-code-index

# Build from source
cd lightning-code-index
make build

MCP Server not connecting

1. Check Claude Desktop config file syntax
2. Verify LCI_ROOT points to valid directory
3. Check logs: View → Developer → Logs
4. Try running manually: npx lightning-code-index daemon

Search returns no results

# Verify index exists
lci stats --root ./project

# Rebuild index
lci index --rebuild ./project

# Check file inclusion
lci index --dry-run ./project --verbose

License

MIT License - see LICENSE file for details.

Contributing

Contributions welcome! Please read CONTRIBUTING.md for guidelines.

Links

• GitHub: https://github.com/standardbeagle/lightning-code-index
• Documentation: https://github.com/standardbeagle/lightning-code-index/wiki
• Issues: https://github.com/standardbeagle/lightning-code-index/issues
• Discussions: https://github.com/standardbeagle/lightning-code-index/discussions

Acknowledgments

• tree-sitter for AST parsing
• urfave/cli for CLI framework
• MCP for the protocol specification