LAIN MCP

What it is

A Rust server that indexes every registered repository into a persistent code graph and answers structural questions across them. A file watcher keeps a volatile overlay fresh while you edit, and the config hot-reloads without a restart.

What you get

• Blast radius, call chains and transitive dependencies for a symbol — get_blast_radius, get_call_chain, trace_dependency
• Files that historically change together — get_coupling_radar
• Orientation in an unfamiliar codebase — find_anchors, list_entry_points, explore_architecture, describe_schema
• Search by meaning with local ONNX embeddings, and a flexible ops-array graph query — semantic_search, query_graph
• Code health — find_dead_code, suggest_refactor_targets, get_coverage_summary
• Explanation and context — explain_symbol, get_context_for_prompt, get_code_snippet
• Architecture reads — navigate_to_anchor, get_layered_map, compare_modules, architectural_observations
• Git state and builds — get_file_diff, get_commit_history, get_branch_status, run_build, run_tests, run_clippy
• Maintenance — sync_state, run_enrichment, export_graph_json, get_agent_strategy, get_health, install_language_server
• A Command Center dashboard served at the root of the HTTP transport

Requirements

Install the binary with the project's install script, register repositories with lain repos add, then start lain server --config ./repos.yaml. lain mcp is the single-repo stdio path and needs no repos.yaml. Semantic search wants an ONNX embedding model — the installer fetches all-MiniLM-L6-v2 with --download-model, and the docs recommend the BGE family instead.

Setup effort

One command — curl -fsSL https://raw.githubusercontent.com/spuentesp/lain/main/install.sh | bash

Tools you get

45 tools named in the project's documentation.

Requires

lain on PATH

Where it runs

The documented client runs the server on your machine.