@spuentesp/lain-mcp

Architectural code intelligence for AI coding agents.

Installation

npm install -g @spuentesp/lain-mcp

If npm fails with EEXIST: file already exists for lain, an unrelated lain file already sits in npm's global bin directory (often an older manual copy). Move or remove it, or install under a different prefix:

npm install -g --prefix ~/.local/lain-npm @spuentesp/lain-mcp

When npm install scripts are disabled (--ignore-scripts, a locked-down CI), the binary is not downloaded at install time. The first lain run fetches and verifies it, so that first run needs network access; once cached, it works offline.

Or with npx (downloads binary on first run):

npx @spuentesp/lain-mcp mcp

What this installs

• A native binary downloaded from the matching GitHub release.
• A cache entry separated by LAIN version and platform target.
• SHA-256 verification against the release's SHA256SUMS file.
• A lain --version check that must match the npm package version.

The launcher downloads into a temporary directory and only moves verified files into the versioned cache. It checks cached binaries again before running them. A verified cache entry works offline.

Published targets

| Host | Target | Current status | |---|---|---| | x86-64 Linux | x86_64-unknown-linux-gnu | Supported | | Apple silicon | aarch64-apple-darwin | Supported | | x86-64 Windows | x86_64-pc-windows-msvc | The repository contains the DirectML.dll packaging repair; v0.7.4 predates it |

The release workflow doesn't currently publish x86-64 macOS or ARM64 Linux archives. On those hosts, build Lain from source.

Configuration

Set LAIN_VERSION to run a different published version. Set LAIN_CACHE_DIR to override the operating system's user cache directory.

Usage

From a repository you want Lain to index, the real path is the setup command — it writes this package's MCP registration into your agent's configuration and verifies the connection:

lain setup --agent claude-code   # also: codex, cursor, vscode, continue, generic

lain setup registers the absolute path of the verified cache binary (see "What this installs"), not the bare lain launcher — MCP hosts rarely inherit the shell PATH that would resolve it. A hand-written entry that calls the launcher works too when PATH reaches it:

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

Or run directly:

npx @spuentesp/lain-mcp mcp

Uninstall

npm uninstall -g @spuentesp/lain-mcp

The verified native binary remains in your user cache so a later install can work offline. Remove the lain cache directory using your operating system's cache-management tools if you also want to discard downloaded versions.