# symgraph

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[![Release](https://github.com/grahambrooks/symgraph/actions/workflows/release.yml/badge.svg)](https://github.com/grahambrooks/symgraph/actions/workflows/release.yml)
[![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](https://opensource.org/licenses/MIT)
[![Rust](https://img.shields.io/badge/rust-1.70%2B-blue.svg)](https://www.rust-lang.org)
[![MCP](https://img.shields.io/badge/MCP-compatible-green.svg)](https://modelcontextprotocol.io)

Semantic code intelligence MCP server - build knowledge graphs of codebases to enhance AI-assisted code exploration.

symgraph is a rust implementation of https://github.com/colbymchenry/codegraph. Why? Ongoing exploration of compiled
binary deployment of MCP Servers.

## Features

- **Multi-language support**: Rust, TypeScript, JavaScript, Python, Go, Java, C, C++
- **Symbol extraction**: functions, classes, methods, structs, interfaces, traits, enums, constants
- **Relationship tracking**: calls, contains, imports, exports, extends, implements
- **Impact analysis**: trace the effect of changes through the codebase
- **Advanced code intelligence**:
    - Find call paths between functions
    - Detect unused/dead code
    - Explore class hierarchies
    - Locate all interface implementations
    - Analyze change impact by line range
- **Incremental indexing**: only re-indexes changed files using content hashing
- **Dual transport**: stdio (default) and HTTP server modes

## Installation

### Homebrew (macOS & Linux)

```sh
brew tap grahambrooks/symgraph https://github.com/grahambrooks/symgraph
brew install symgraph
```

This installs the `symgraph` binary (CLI + MCP server) and the lean `symgraph-cli`
from the latest GitHub release. Upgrade with `brew upgrade symgraph`. The tap points
at this repository directly, so no separate `homebrew-*` repo is required.

### macOS & Linux (install script)

```sh
curl -fsSL https://raw.githubusercontent.com/grahambrooks/symgraph/main/install.sh | bash
```

To also configure symgraph as an MCP server for Claude Code and Claude Desktop:

```sh
curl -fsSL https://raw.githubusercontent.com/grahambrooks/symgraph/main/install.sh | bash -s -- --mcp
```

Install a specific version:

```sh
SYMGRAPH_VERSION=2026.3.30 curl -fsSL https://raw.githubusercontent.com/grahambrooks/symgraph/main/install.sh | bash
```

### Windows (PowerShell)

```powershell
irm https://raw.githubusercontent.com/grahambrooks/symgraph/main/install.ps1 -OutFile install.ps1; .\install.ps1
```

To also configure symgraph as an MCP server for Claude Code and Claude Desktop:

```powershell
irm https://raw.githubusercontent.com/grahambrooks/symgraph/main/install.ps1 -OutFile install.ps1; .\install.ps1 -Mcp
```

Install a specific version:

```powershell
$env:SYMGRAPH_VERSION="2026.3.30"; irm https://raw.githubusercontent.com/grahambrooks/symgraph/main/install.ps1 -OutFile install.ps1; .\install.ps1
```

Both scripts install to `~/.symgraph/bin/` by default. Override with `SYMGRAPH_INSTALL_DIR`.

### Claude Desktop (MCPB Bundle)

Download and install the MCPB bundle for your platform:

| Platform              | Download                                                                                   |
|-----------------------|--------------------------------------------------------------------------------------------|
| macOS (Apple Silicon) | [symgraph-x.x.x-darwin-arm64.mcpb](https://github.com/grahambrooks/symgraph/releases/latest) |
| macOS (Intel)         | [symgraph-x.x.x-darwin-x64.mcpb](https://github.com/grahambrooks/symgraph/releases/latest)   |
| Windows               | [symgraph-x.x.x-windows-x64.mcpb](https://github.com/grahambrooks/symgraph/releases/latest)  |
| Linux                 | [symgraph-x.x.x-linux-x64.mcpb](https://github.com/grahambrooks/symgraph/releases/latest)    |

1. Download the `.mcpb` file for your platform from [Releases](https://github.com/grahambrooks/symgraph/releases/latest)
2. Open Claude Desktop
3. Drag and drop the `.mcpb` file onto Claude Desktop, or use **File > Install MCP Server**
4. Configure the project root when prompted

### From Source

```bash
git clone https://github.com/grahambrooks/symgraph
cd symgraph
make install
```

## Usage

### Index a Codebase

```bash
# Index current directory
symgraph index

# Index specific directory
symgraph index ~/projects/myapp
```

### Start MCP Server

```bash
# Start with stdio transport (for Claude Desktop)
symgraph serve

# Start with HTTP transport
symgraph serve --port 8080
```

### CLI Commands

Almost every MCP tool is also a CLI subcommand (handy for testing and for
agents driven by a CLI skill instead of MCP). Run `symgraph help` for the full
list with arguments and options.

```bash
# Core
symgraph index [path]                 # Index a codebase
symgraph serve [--port <PORT>]        # Start the MCP server (stdio / HTTP)
symgraph status [path]                # Show index statistics
symgraph search <query>               # Find symbols by name
symgraph context <task...>            # Build context for a task
symgraph where [path]                 # Show where the index is stored
symgraph prune                        # Remove stale cached indexes

# Symbol relationships (query the current project's index)
symgraph callers <symbol>             # Who calls this symbol
symgraph callees <symbol>             # What this symbol calls
symgraph references <symbol>          # All references to a symbol
symgraph node <symbol>                # Detailed symbol info
symgraph definition <symbol>          # Source of a symbol [--context-lines N]
symgraph hierarchy <symbol>           # Parent/child (contains) hierarchy
symgraph implementations <symbol>     # Interface/trait implementations
symgraph file <path>                  # Symbols defined in a file
symgraph path <from> <to>             # Call path(s) between two symbols
symgraph unused                       # Dead code (no incoming references)

# Impact, git history & coupling
symgraph impact <symbol> [--churn]    # Change impact + coupling breakdown
symgraph diff-impact [--git-ref REF]  # Impact of a region / diff
symgraph blame <symbol>               # git blame a symbol's definition
symgraph churn [path] [--days N]      # File change frequency (volatility)
symgraph module-graph [--granularity file|dir|module]   # Deps, fan-in/out, cycles
symgraph coupling-score [--churn]     # Rank coupling: strength × distance × volatility
symgraph god-struct [--churn]         # Structs ranked by architectural debt
symgraph dispatch-sites <enum>        # Files that match/switch on an enum
```

Add `--format json` for machine-readable output (supported by every command
except `blame`, `churn`, and `diff-impact`), and `--db <path>` to point at a
specific index database. The MCP tools accept the same `format: "json"`
argument — both surfaces render through one shared `ops` layer, so CLI and
server output match.

## MCP Tools

### Core Tools

| Tool                 | Description                                       |
|----------------------|---------------------------------------------------|
| `symgraph-context`    | Build focused code context for a specific task    |
| `symgraph-search`     | Quick symbol search by name                       |
| `symgraph-callers`    | Find all callers of a symbol                      |
| `symgraph-callees`    | Find all callees of a symbol                      |
| `symgraph-impact`     | Impact + inbound coupling breakdown (contract/model/intrusive) |
| `symgraph-node`       | Get detailed symbol information                   |
| `symgraph-definition` | Get the full source code of a symbol with context |
| `symgraph-file`       | List all symbols defined in a specific file       |
| `symgraph-references` | Find all references to a symbol                   |
| `symgraph-reindex`    | Trigger incremental reindexing of changed files   |
| `symgraph-status`     | Get index statistics                              |

### Advanced Tools

| Tool                      | Description                                             |
|---------------------------|---------------------------------------------------------|
| `symgraph-hierarchy`       | Get class/module hierarchy (parent/child relationships) |
| `symgraph-path`            | Find call paths between two symbols                     |
| `symgraph-unused`          | Find unused/dead code with no incoming references       |
| `symgraph-implementations` | Find all implementations of an interface/trait          |
| `symgraph-diff-impact`     | Analyze the impact of changing a specific code region   |

### Git-aware Tools

| Tool               | Description                                              |
|--------------------|---------------------------------------------------------|
| `symgraph-blame`   | Git blame a symbol's definition lines                   |
| `symgraph-churn`   | File change frequency over a recent window (volatility) |

### Coupling Analysis Tools

These fold the resolved graph onto the strength × distance × volatility
framework. Edges come from `accesses` (field reads), `mutates` (field
writes / `&mut`), `imports`, and enum-dispatch `references` — so **run
`symgraph-reindex` after code changes** to populate them. Resolution is
name-based (heuristic), best for ranking hotspots. All accept `format="json"`.

| Tool                      | Description                                                        |
|---------------------------|-------------------------------------------------------------------|
| `symgraph-module-graph`   | Dependency adjacency, fan-in/fan-out, and cycles (SCCs) at a `file`/`dir`/`module` boundary |
| `symgraph-coupling-score` | Rank module-pair coupling by strength × distance × volatility (churn) |
| `symgraph-god-struct`     | Rank structs/classes by pub-field × inbound-refs × churn (architectural debt) |
| `symgraph-dispatch-sites` | Find every file that matches/switches on an enum's members (control coupling) |

### Example Use Cases

**Find dead code for cleanup:**

```
Use symgraph-unused to find all unused functions and classes
```

**Understand function call chains:**

```
Use symgraph-path with from="main" and to="database_query" to see how data flows
```

**Assess change impact:**

```
Use symgraph-diff-impact with file_path="src/auth.rs" start_line=45 end_line=60
to see what would be affected by changes in that region
```

**Explore OOP hierarchies:**

```
Use symgraph-hierarchy with symbol="BaseHandler" to see all parent/child relationships
```

**Find all trait implementations:**

```
Use symgraph-implementations with symbol="Iterator" to find all structs implementing Iterator
```

## Project Setup

Add symgraph to your project in two steps: index your code, then configure your AI tool.

### Step 1: Index Your Project

```bash
cd /path/to/your/project
symgraph index
```

This creates a `.symgraph/` directory containing the SQLite knowledge graph. Add `.symgraph/` to your `.gitignore`.

Re-run `symgraph index` after significant code changes, or use the `symgraph-reindex` MCP tool to incrementally update from within your AI tool.

### Step 2: Configure Your AI Tool

#### Claude Code

Register symgraph as an MCP server for your project:

```bash
cd /path/to/your/project
claude mcp add symgraph -- symgraph serve
```

Or add `.mcp.json` to your project root:

```json
{
  "mcpServers": {
    "symgraph": {
      "type": "stdio",
      "command": "symgraph",
      "args": ["serve"]
    }
  }
}
```

**Optional: Install the `code-intelligence` plugin** for the guided
`/explore-code` skill (plus a SessionStart hook that auto-indexes new projects).
The skill now ships via the [gb-agent-skills](https://github.com/grahambrooks/gb-agent-skills)
plugin marketplace rather than being copied into your project. In Claude Code:

```
/plugin marketplace add grahambrooks/gb-agent-skills
/plugin install code-intelligence@gb-agent-skills
```

The plugin uses [`bx`](https://github.com/grahambrooks/bx) to launch the symgraph
MCP server on demand, so install `bx` first. Once installed, use the skill in
Claude Code:

```
/explore-code how does the authentication middleware work?
/explore-code what would break if I changed the User struct?
```

#### Claude Desktop

**Via MCPB bundle (easiest):**

1. Download the `.mcpb` file for your platform from [Releases](https://github.com/grahambrooks/symgraph/releases/latest)
2. Drag and drop onto Claude Desktop, or use **File > Install MCP Server**
3. Set the project root when prompted

**Via manual config** — add to `claude_desktop_config.json`:

```json
{
  "mcpServers": {
    "symgraph": {
      "command": "symgraph",
      "args": ["serve"],
      "env": {
        "SYMGRAPH_ROOT": "/path/to/your/project"
      }
    }
  }
}
```

#### GitHub Copilot

**Per-repository** — add `.copilot/mcp.json` to your project:

```json
{
  "mcpServers": {
    "symgraph": {
      "command": "symgraph",
      "args": ["serve"]
    }
  }
}
```

**VS Code user settings** — add to `settings.json`:

```json
{
  "github.copilot.chat.mcp.servers": {
    "symgraph": {
      "command": "symgraph",
      "args": ["serve"],
      "env": {
        "SYMGRAPH_ROOT": "${workspaceFolder}"
      }
    }
  }
}
```

See [GitHub Copilot MCP documentation](https://docs.github.com/copilot/customizing-copilot/using-model-context-protocol/extending-copilot-chat-with-mcp) for more details.

#### OpenAI Codex

```bash
codex mcp add symgraph --command "symgraph" --args "serve"
```

Or add to `~/.codex/config.toml`:

```toml
[mcp_servers.symgraph]
command = "symgraph"
args = ["serve"]
```

See [OpenAI Codex MCP documentation](https://developers.openai.com/codex/mcp/) for more details.

#### HTTP Mode (Any MCP Client)

For shared or remote setups, run symgraph as an HTTP server:

```bash
symgraph serve --port 8080
```

Then point your MCP client at `http://localhost:8080/mcp`.

### Environment Variables

| Variable             | Description                                   | Default           |
|----------------------|-----------------------------------------------|-------------------|
| `SYMGRAPH_ROOT`      | Project root directory                        | Current directory |
| `SYMGRAPH_DB`        | Explicit index database path (highest priority) | —               |
| `SYMGRAPH_STORAGE`   | Index location strategy: `git` / `cache` / `local` | auto         |
| `SYMGRAPH_IN_MEMORY` | `1` ⇒ ephemeral in-memory index (no disk writes) | off            |
| `SYMGRAPH_AUTH_TOKEN`| Bearer token for HTTP `/mcp`                  | —                 |

### Index Storage

The index is persistent and shared between the CLI and the MCP server, so you
`symgraph index` once and both use it. The location is resolved by this chain
(use `symgraph where` to see what's chosen):

1. **`--db <path>` / `SYMGRAPH_DB`** — explicit override.
2. **`--in-memory` / `SYMGRAPH_IN_MEMORY=1`** — ephemeral (good for long-running
   MCP sessions, CI, and read-only checkouts; rebuilt on start).
3. **`SYMGRAPH_STORAGE`** strategy, or the **auto** default:
   - reuse an existing `.symgraph/` if present (back-compat), else
   - **`git`** → `<git-common-dir>/symgraph/index.db` — co-located with the repo,
     never tracked, **no `.gitignore` entry needed** (the default in a git repo;
     handles worktrees/submodules), else
   - **`cache`** → an OS cache dir keyed by the repo path (for non-git dirs).

`symgraph prune` removes cached indexes whose source repo no longer exists.
`local` storage writes a self-`.gitignore` so even in-tree indexes don't dirty
`git status`.

## Architecture

```
symgraph/
├── src/
│   ├── main.rs          # CLI entry point
│   ├── lib.rs           # Core indexing logic
│   ├── types.rs         # Type definitions (Node, Edge, etc.)
│   ├── db/              # SQLite database operations
│   ├── extraction/      # Tree-sitter code extraction
│   ├── graph/           # Graph traversal algorithms
│   ├── context/         # Context building for AI tasks
│   └── mcp/             # MCP protocol handlers
└── .symgraph/
    └── index.db         # SQLite database (per-project)
```

### Core Concepts

- **Node**: A code symbol (function, class, method, etc.)
- **Edge**: A relationship between nodes (calls, contains, imports, etc.)
- **Knowledge Graph**: The complete set of nodes and edges for a codebase

## Development

### Prerequisites

- Rust 1.70+
- SQLite (bundled via rusqlite)

### Building

```bash
make build           # Release build
make test            # Run tests
make check           # Format, lint, and test
make install         # Build and install to /usr/local/bin
```

### Project Structure

| Module       | Description                                                |
|--------------|------------------------------------------------------------|
| `types`      | Core type definitions (NodeKind, EdgeKind, Language, etc.) |
| `db`         | SQLite database schema and operations                      |
| `extraction` | Tree-sitter based code parsing and symbol extraction       |
| `graph`      | Graph algorithms (callers, callees, impact analysis)       |
| `context`    | Context builder for AI task assistance                     |
| `mcp`        | MCP protocol server implementation                         |

## License

MIT