# LabMCP

A collection of Model Context Protocol (MCP) servers written in Go.

## NixOS Options MCP Server

Search and query NixOS configuration options across multiple nixpkgs revisions. Designed to help Claude (and other MCP clients) answer questions about NixOS configuration.

### Features

- Full-text search across option names and descriptions
- Query specific options with type, default, example, and declarations
- Index multiple nixpkgs revisions (by git hash or channel name)
- Fetch nixpkgs module source files
- Support for PostgreSQL and SQLite backends

## Installation

### Using Nix Flakes

```bash
# Build the package
nix build github:torjus/labmcp

# Or run directly
nix run github:torjus/labmcp -- --help
```

### From Source

```bash
go install git.t-juice.club/torjus/labmcp/cmd/nixos-options@latest
```

## Usage

### As MCP Server

Configure in your MCP client (e.g., Claude Desktop):

```json
{
  "mcpServers": {
    "nixos-options": {
      "command": "nixos-options",
      "args": ["serve"],
      "env": {
        "NIXOS_OPTIONS_DATABASE": "sqlite:///path/to/nixos-options.db"
      }
    }
  }
}
```

Then start the server:

```bash
nixos-options serve
```

### CLI Examples

**Index a nixpkgs revision:**

```bash
# Index by channel name
nixos-options index nixos-unstable

# Index by git hash
nixos-options index e6eae2ee2110f3d31110d5c222cd395303343b08

# Index with file contents (enables get_file tool, slower)
nixos-options index --files nixos-unstable
```

**List indexed revisions:**

```bash
nixos-options list
```

**Search for options:**

```bash
# Basic search
nixos-options search nginx

# Limit results
nixos-options search -n 10 postgresql

# Search in specific revision
nixos-options search -r nixos-unstable firewall
```

**Get option details:**

```bash
nixos-options get services.nginx.enable
nixos-options get services.postgresql.package
```

**Delete an indexed revision:**

```bash
nixos-options delete nixos-23.11
```

## Configuration

### Environment Variables

| Variable | Description | Default |
|----------|-------------|---------|
| `NIXOS_OPTIONS_DATABASE` | Database connection string | `sqlite://nixos-options.db` |

### Database Connection Strings

**SQLite:**
```bash
export NIXOS_OPTIONS_DATABASE="sqlite:///path/to/database.db"
export NIXOS_OPTIONS_DATABASE="sqlite://:memory:"  # In-memory
```

**PostgreSQL:**
```bash
export NIXOS_OPTIONS_DATABASE="postgres://user:pass@localhost/nixos_options?sslmode=disable"
```

### Command-Line Flags

The database can also be specified via the `-d` or `--database` flag:

```bash
nixos-options -d "postgres://localhost/nixos" serve
nixos-options -d "sqlite://my.db" index nixos-unstable
```

## MCP Tools

When running as an MCP server, the following tools are available:

| Tool | Description |
|------|-------------|
| `search_options` | Search for options by name or description |
| `get_option` | Get full details for a specific option |
| `get_file` | Fetch source file contents from nixpkgs |
| `index_revision` | Index a nixpkgs revision |
| `list_revisions` | List all indexed revisions |
| `delete_revision` | Delete an indexed revision |

## Development

```bash
# Enter development shell
nix develop

# Run tests
go test ./...

# Run benchmarks
go test -bench=. ./internal/database/...

# Build
go build ./cmd/nixos-options
```

## License

MIT