Skillget

code-graph-mcp

mcp
SUMMARY

AST knowledge graph MCP server for Claude Code — semantic search, call graph traversal, HTTP route tracing, impact analysis. Auto-indexes 10 languages via Tree-sitter.

README.md

code-graph-mcp

A high-performance code knowledge graph server implementing the Model Context Protocol (MCP). Indexes codebases into a structured AST knowledge graph with semantic search, call graph traversal, and HTTP route tracing — designed to give AI coding assistants deep, structured understanding of your code.

Features

  • Multi-language parsing — Tree-sitter AST extraction for 16 languages: TypeScript, JavaScript, Go, Python, Rust, Java, C, C++, C#, Kotlin, Ruby, PHP, Swift, Dart, HTML, CSS
  • Semantic code search — Hybrid BM25 full-text + vector semantic search with Reciprocal Rank Fusion (RRF), powered by sqlite-vec
  • Call graph traversal — Recursive CTE queries to trace callers/callees with cycle detection
  • HTTP route tracing — Map route paths to backend handler functions (Express, Flask/FastAPI, Go, ASP.NET, Rails, Laravel, Vapor)
  • Dead code detection — Find unreferenced symbols with smart Orphan/Exported-Unused classification
  • Impact analysis — Determine the blast radius of code changes by tracing all dependents
  • Incremental indexing — Merkle tree change detection with file system watcher for real-time updates. Smart event filtering skips metadata-only changes (chmod, xattr)
  • Context compression — Token-aware snippet extraction for LLM context windows (L0→full code, L1→summaries, L2→file groups, L3→directory overview). Compact JSON output saves 15-20% tokens
  • Embedding model — Optional local embedding via Candle (feature-gated embed-model). Context reordered to prioritize structural relations over code for better embedding quality
  • Self-healing — Automatic SQLite corruption recovery with rebuild. Startup repair for incomplete indexing (Phase 3 failures)
  • MCP protocol — JSON-RPC 2.0 over stdio, plug-and-play with Claude Code, Cursor, Windsurf, and other MCP clients
  • Claude Code Plugin — First-class plugin with slash commands (/understand, /trace, /impact), agents, skills, auto-indexing hooks, StatusLine integration, and self-updating

Why code-graph-mcp?

Unlike naive full-text search or simple AST dumps, code-graph-mcp builds a structured knowledge graph that understands the relationships between symbols across your entire codebase.

Incremental by Design

BLAKE3 Merkle tree tracks every file's content hash. On re-index, only changed files are re-parsed — unchanged directory subtrees are skipped entirely via mtime cache. When a function signature changes, dirty propagation automatically regenerates context for all downstream callers across files.

Hybrid Search, Not Just Grep

Combines BM25 full-text ranking (FTS5) with vector semantic similarity (sqlite-vec) via Reciprocal Rank Fusion (RRF) with raw score blending — so searching "handle user login" finds the right function even if it's named authenticate_session. Results are auto-compressed to fit LLM context windows.

Scope-Aware Relation Extraction

The parser doesn't just find function calls — it tracks them within their proper scope context. Extracts calls, imports, inheritance, interface implementations, exports, and HTTP route bindings. Same-file targets are preferred over cross-file matches to minimize false-positive edges.

HTTP Request Flow Tracing

Unique to code-graph-mcp: trace from GET /api/users → route handler → service layer → database call in a single query. Supports Express, Flask/FastAPI, and Go HTTP frameworks.

Zero External Dependencies at Runtime

Single binary, embedded SQLite, bundled sqlite-vec extension, optional local embedding model via Candle — no database server, no cloud API, no Docker required. Runs entirely on your machine.

Built for AI Assistants

Every design decision — from token-aware compression to node_id-based snippet expansion — is optimized for LLM context windows. Works out of the box with Claude Code, Cursor, Windsurf, and any MCP-compatible client.

Performance

Metric Value
Indexing speed 300+ files/second (single-threaded, release build)
Incremental re-index <250ms no-change detection via BLAKE3 Merkle tree
FTS search P50 / P99 <300us / <1ms
Database overhead ~3.5MB per 800 nodes
Token savings 5-20x fewer tokens per code understanding task vs grep+read

Run code-graph-mcp benchmark on your own project to measure.

Efficiency: code-graph vs Traditional Tools

Real-world benchmarks comparing code-graph-mcp tools against traditional approaches (Grep + Read + Glob) on a 33-file Rust project (~537 AST nodes).

Tool Call Reduction

Scenario Traditional code-graph Savings
Project architecture overview 5-8 calls 1 call (project_map) ~85%
Find function by concept 3-5 calls 1 call (semantic_code_search) ~75%
Trace 2-level call chain 8-15 calls 1 call (get_call_graph) ~90%
Pre-change impact analysis 10-20+ calls 1 call (impact_analysis) ~95%
Module structure & exports 5+ calls 1 call (module_overview) ~80%
File dependency mapping 3-5 calls 1 call (dependency_graph) ~75%
Similar code detection N/A 1 call (find_similar_code) unique

Overall Session Efficiency

Metric Without code-graph With code-graph Improvement
Tool calls per navigation task ~6 ~1.2 ~80% fewer
Source lines read into context ~8,000 lines ~400 lines (structured) ~95% less
Navigation token cost ~36K tokens ~7K tokens ~80% saved
Full session token savings — — 40-60%

What code-graph Uniquely Enables

  • Impact analysis — "Changing conn affects 33 functions across 4 files, 78 tests at HIGH risk" — impossible to derive manually with Grep
  • Transitive call tracing — Follow main → run_serve → handle_message → handle_tools_call → conn in one query
  • Semantic search — Find authenticate_session when searching "handle user login"
  • Dependency strength — Not just "file A imports file B", but "file A uses 38 symbols from file B"

When Traditional Tools Are Still Better

Use Case Best Tool
Exact string / constant search Grep
Reading a file to edit it Read
Finding files by name pattern Glob

Architecture

src/
├── domain.rs     # Shared constants, relation types, env-var config
├── mcp/          # MCP protocol layer (JSON-RPC, tool registry, server)
│   └── server/   # McpServer with IndexingState + CacheState sub-structs
├── parser/       # Tree-sitter parsing, relation extraction, LanguageConfig dispatch
├── indexer/      # 3-phase pipeline, Merkle tree, file watcher
├── storage/      # SQLite schema (v6), CRUD, FTS5, migrations
├── graph/        # Recursive CTE call graph queries
├── search/       # RRF fusion search combining BM25 + vector
├── embedding/    # Candle embedding model (optional, masked mean pooling)
├── sandbox/      # Context compressor with token estimation
└── utils/        # Language detection, config

Installation

Option 1: Claude Code Plugin (Recommended)

Install as a Claude Code plugin for the best experience — includes slash commands, agents, skills, auto-indexing hooks, StatusLine health display, and automatic updates:

# Step 1: Add the marketplace
/plugin marketplace add sdsrss/code-graph-mcp

# Step 2: Install the plugin
/plugin install code-graph-mcp

What you get:

  • MCP Server — All code-graph tools available to Claude
  • Slash Commands — /understand <module>, /trace <route>, /impact <symbol>
  • Code Explorer Agent — Deep code understanding expert via code-explorer
  • Auto-indexing Hook — Incremental index on every file edit (PostToolUse)
  • StatusLine — Real-time health display (nodes, files, watch status) — compatible with other plugins' StatusLine via composite multiplexer
  • Auto-update — Checks for new versions every 6h, updates silently

Manual Update

npm update -g @sdsrs/code-graph

Then reconnect the MCP server in Claude Code with /mcp.

Note: Auto-update is disabled in the source repo directory (dev mode). Use manual update when developing the plugin itself.

Option 2: Claude Code MCP Server Only

Register as an MCP server without the plugin features:

claude mcp add code-graph-mcp -- npx -y @sdsrs/code-graph

Option 3: Cursor / Windsurf / Other MCP Clients

Add to your MCP settings file (e.g. ~/.cursor/mcp.json):

{
  "mcpServers": {
    "code-graph": {
      "command": "npx",
      "args": ["-y", "@sdsrs/code-graph"]
    }
  }
}

Option 4: npx (No Install)

Run directly without installing:

npx -y @sdsrs/code-graph

Option 5: npm (Global Install)

Install globally, then run anywhere:

npm install -g @sdsrs/code-graph
code-graph-mcp

Uninstallation

Claude Code Plugin

# Uninstall the plugin
/plugin uninstall code-graph-mcp

# (Optional) Remove the marketplace
/plugin marketplace remove code-graph-mcp

# (Optional) Clean up all config and cache data
node ~/.claude/plugins/cache/code-graph-mcp/code-graph-mcp/*/scripts/lifecycle.js uninstall

Claude Code MCP Server

claude mcp remove code-graph-mcp

Cursor / Windsurf / Other MCP Clients

Remove the code-graph entry from your MCP settings file (e.g. ~/.cursor/mcp.json).

npm (Global)

npm uninstall -g @sdsrs/code-graph

MCP Tools

Tool Description
project_map Full project architecture: modules, dependencies, entry points, hot functions
semantic_code_search Hybrid BM25 + vector + graph search for AST nodes
get_call_graph Trace upstream/downstream call chains for a function
trace_http_chain Full request flow: route → handler → downstream call chain
impact_analysis Analyze the blast radius of changing a symbol
module_overview High-level overview of a module's structure and exports
dependency_graph Visualize dependency relationships between modules. Supports compact mode
find_similar_code Find semantically similar code via embeddings. Requires symbol_name or node_id
get_ast_node Extract a specific code symbol with signature, body, and relations. Supports compact mode
ast_search Search AST nodes by text and/or structural filters (type, return type, params)
find_references Find all references to a symbol (callers, importers, inheritors). Supports compact mode
find_dead_code Find unused code — orphan symbols and exported-but-unused public APIs

CLI Commands

All tools are also available as CLI subcommands for shell scripts, hooks, and terminal workflows:

Command MCP Equivalent Description
search <query> semantic_code_search FTS5 search by concept
ast-search [query] ast_search Structural search with --type/--returns/--params filters
callgraph <symbol> get_call_graph Show call graph (callers/callees)
impact <symbol> impact_analysis Impact analysis (callers, routes, risk level)
show <symbol> get_ast_node Show symbol details (code, type, signature)
map project_map Project architecture map
overview <path> module_overview Module symbols grouped by file and type
deps <file> dependency_graph File-level dependency graph
trace <route> trace_http_chain Trace HTTP route → handler → downstream calls
similar <symbol> find_similar_code Find semantically similar code (requires embeddings)
refs <symbol> find_references Find all references to a symbol
dead-code [path] find_dead_code Find unused code (orphans and exported-unused)
grep <pattern> — AST-context grep (ripgrep + containing function/class)
incremental-index — Run incremental index update (auto-creates DB if needed)
health-check get_index_status Query index status and freshness
benchmark — Benchmark index speed, query latency, token savings

Common options: --json (JSON output), --compact (compact output), --limit N, --depth N, --file <path>.

Plugin Slash Commands

Available when installed as a Claude Code plugin:

Command Description
/understand <module> Deep dive into a module or file's architecture and relationships
/trace <route> Trace a full HTTP request flow from route to data layer
/impact <symbol> Analyze the impact scope of changing a symbol before modifying it
/status Show code-graph index status and embedding progress
/rebuild Force a full code-graph index rebuild

Supported Languages (16)

Language Extensions Relations Extracted
TypeScript .ts, .tsx calls, imports, exports, inherits, implements, routes_to
JavaScript .js, .jsx, .mjs, .cjs calls, imports, exports, inherits, routes_to
Go .go calls, imports, routes_to
Python .py, .pyi calls, imports, inherits, routes_to
Rust .rs calls, imports, inherits, implements
Java .java calls, imports, inherits, implements
C# .cs calls, imports, inherits, implements
Kotlin .kt, .kts calls, imports, inherits
Ruby .rb calls, imports, inherits
PHP .php calls, imports, inherits, implements
Swift .swift calls, imports, inherits
Dart .dart calls, imports, implements
C .c, .h calls, imports
C++ .cpp, .cc, .cxx, .hpp calls, imports, inherits
HTML .html, .htm structural parsing
CSS .css structural parsing

Storage

Uses SQLite with:

  • FTS5 for full-text search
  • sqlite-vec extension for vector similarity search
  • Merkle tree hashes for incremental change detection

Data is stored in .code-graph/index.db under the project root (auto-created, gitignored).

Build from Source

Prerequisites

  • Rust 1.75+ (2021 edition)
  • A C compiler (for bundled SQLite / sqlite-vec)

Build

# Default build (with local embedding model)
cargo build --release

# Without embedding model (lighter build)
cargo build --release --no-default-features

Configure (from source)

Add the compiled binary to your MCP settings:

{
  "mcpServers": {
    "code-graph": {
      "command": "/path/to/target/release/code-graph-mcp"
    }
  }
}

Development

# Run tests
cargo test

# Run tests without embedding model
cargo test --no-default-features

# Check compilation
cargo check

# Run performance benchmarks (indexing, search, call graph)
cargo bench --no-default-features

License

See LICENSE for details.

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