narsil-mcp

The blazing-fast, privacy-first MCP server for deep code intelligence

A Rust-powered MCP (Model Context Protocol) server providing AI assistants with deep code understanding through 90 specialized tools.

Why narsil-mcp?

Key Features

• Code Intelligence - Symbol extraction, semantic search, call graph analysis
• Neural Semantic Search - Find similar code using embeddings (Voyage AI, OpenAI)
• Security Analysis - Taint analysis, vulnerability scanning, OWASP/CWE coverage
• Supply Chain Security - SBOM generation, dependency auditing, license compliance
• Advanced Analysis - Control flow graphs, data flow analysis, dead code detection

Why Choose narsil-mcp?

• Written in Rust - Blazingly fast, memory-safe, single binary (~30MB)
• Tree-sitter powered - Accurate, incremental parsing for 32 languages
• Zero config - Point at repos and go
• MCP compliant - Works with Claude, Cursor, VS Code Copilot, Zed, and any MCP client
• Privacy-first - Fully local, no data leaves your machine
• Parallel indexing - Uses all cores via Rayon
• Smart excerpts - Expands to complete syntactic scopes
• Security-first - Built-in vulnerability detection and taint analysis
• Neural embeddings - Optional semantic search with Voyage AI or OpenAI
• WASM support - Run in browser with WebAssembly build
• Real-time streaming - Results as indexing progresses for large repos

Supported Languages

Available Tools (90)

Repository & File Management

Symbol Search & Navigation

Code Search

AST-Aware Chunking

Neural Semantic Search (requires --neural)

Call Graph Analysis (requires --call-graph)

Control Flow Analysis

Data Flow Analysis

Type Inference (Python/JavaScript/TypeScript)

Import/Dependency Graph

Security Analysis - Taint Tracking

Security Analysis - Rules Engine

Supply Chain Security

Git Integration (requires --git)

LSP Integration (requires --lsp)

Remote Repository Support (requires --remote)

Metrics

SPARQL / Knowledge Graph (requires --graph)

Code Context Graph (CCG) (requires --graph)

CCG provides standardized, AI-consumable representations of codebases in tiered layers.

Security Rules

narsil-mcp includes built-in security rules in rules/:

Core Rulesets:

• owasp-top10.yaml - OWASP Top 10 2021 vulnerability patterns
• cwe-top25.yaml - CWE Top 25 Most Dangerous Weaknesses
• crypto.yaml - Cryptographic issues (weak algorithms, hardcoded keys)
• secrets.yaml - Secret detection (API keys, passwords, tokens)

Language-Specific Rules:

• rust.yaml - Rust security patterns (unsafe transmute, FFI boundaries, command injection, TOCTOU)
• elixir.yaml - Elixir/BEAM patterns (atom exhaustion, binary_to_term, Code.eval, Ecto SQL injection)
• go.yaml - Go security patterns (SQL injection, TLS, command injection)
• java.yaml - Java vulnerabilities (XXE, deserialization, LDAP injection)
• csharp.yaml - C# security issues (deserialization, XSS, path traversal)
• kotlin.yaml - Kotlin/Android patterns (WebView, intents, secrets)
• bash.yaml - Shell script vulnerabilities (command injection, eval)

Infrastructure & Configuration:

• iac.yaml - Infrastructure as Code (Terraform, CloudFormation, Kubernetes)
• config.yaml - Configuration file security (hardcoded credentials, insecure settings)

Custom rules can be loaded with scan_security --ruleset /path/to/rules.yaml.

Architecture

+-----------------------------------------------------------------+
|                         MCP Server                               |
|  +-----------------------------------------------------------+  |
|  |                   JSON-RPC over stdio                      |  |
|  +-----------------------------------------------------------+  |
|                              |                                   |
|  +---------------------------v-------------------------------+  |
|  |                   Code Intel Engine                        |  |
|  |  +------------+ +------------+ +------------------------+  |  |
|  |  |  Symbol    | |   File     | |    Search Engine       |  |  |
|  |  |  Index     | |   Cache    | |  (Tantivy + TF-IDF)    |  |  |
|  |  | (DashMap)  | | (DashMap)  | +------------------------+  |  |
|  |  +------------+ +------------+                              |  |
|  |  +------------+ +------------+ +------------------------+  |  |
|  |  | Call Graph | |  Taint     | |   Security Rules       |  |  |
|  |  |  Analysis  | |  Tracker   | |   Engine               |  |  |
|  |  +------------+ +------------+ +------------------------+  |  |
|  +-----------------------------------------------------------+  |
|                              |                                   |
|  +---------------------------v-------------------------------+  |
|  |                Tree-sitter Parser                          |  |
|  |  +------+ +------+ +------+ +------+ +------+             |  |
|  |  | Rust | |Python| |  JS  | |  TS  | | Go   | ...         |  |
|  |  +------+ +------+ +------+ +------+ +------+             |  |
|  +-----------------------------------------------------------+  |
|                              |                                   |
|  +---------------------------v-------------------------------+  |
|  |                Repository Walker                           |  |
|  |           (ignore crate - respects .gitignore)             |  |
|  +-----------------------------------------------------------+  |
+-----------------------------------------------------------------+

Performance

Benchmarked on Apple M1 (criterion.rs):

Parsing Throughput

Search Latency

End-to-End Indexing

Key metrics:

• Tree-sitter parsing: ~2 GiB/s sustained throughput
• Symbol lookup: <1µs for exact match
• Full-text search: <1ms for most queries
• Hybrid search runs BM25 + TF-IDF in parallel via rayon

Development

# Run the full test suite
cargo test

# Run benchmarks (criterion.rs)
cargo bench

# Run with debug logging
RUST_LOG=debug cargo run -- --repos ./test-fixtures

# Format code
cargo fmt

# Lint
cargo clippy

# Test with MCP Inspector
npx @modelcontextprotocol/inspector ./target/release/narsil-mcp --repos ./path/to/repo

Roadmap

Completed

• Multi-language symbol extraction (32 languages)
• Full-text search with Tantivy (BM25 ranking)
• Hybrid search (BM25 + TF-IDF with RRF)
• AST-aware code chunking
• Git blame/history integration
• Call graph analysis with complexity metrics
• Control flow graph (CFG) analysis
• Data flow analysis (DFG) with reaching definitions
• Dead code and dead store detection
• Taint analysis for injection vulnerabilities
• Security rules engine (OWASP, CWE, crypto, secrets)
• SBOM generation (CycloneDX, SPDX)
• Dependency vulnerability checking (OSV)
• License compliance analysis
• Import graph with circular dependency detection
• Cross-language symbol resolution
• Incremental indexing with Merkle trees
• Index persistence
• Watch mode for file changes
• LSP integration
• Remote repository support
• Streaming responses

What's New

v1.6.x (Current)

• Crash-proof chunking - Fixed unsafe byte-level string slicing in chunk_file() and extract_signature() that caused hybrid_search, search_chunks, and get_chunk_stats to crash when processing files with multi-byte UTF-8 characters (emoji, CJK, accented chars). All byte slicing now uses safe content.get() with fallback.
• NaN-safe sort operations - Fixed 5 locations across search, embeddings, git, index, and extract modules where partial_cmp().unwrap() would panic on NaN float values. All sorts now use unwrap_or(Ordering::Equal).
• Defense-in-depth chunking - Added catch_unwind wrappers around all repo-wide chunk_file() loops so a panic in one file skips it instead of crashing the entire MCP server.
• Visualization frontend overhaul - Full SPA with HashRouter routing, file tree sidebar, syntax-highlighted code viewer, dashboard, and per-repo overview pages
• Graph view performance - Import graph now uses cached index data instead of filesystem walks; symbol graph iterates file cache directly instead of markdown round-trips; all views respect max_nodes for early termination
• Real control flow graphs - Flow view now uses the real CFG builder (cfg::analyze_function) with proper basic blocks, branch conditions, and loop back-edges instead of the single-block stub
• Hybrid graph budget splitting - Hybrid view allocates 60/40 node budget between call and import graphs for balanced results
• Fix #14: configurable embedding dimensions - Added --neural-dimension CLI arg and default_dimension_for_model() lookup so models like text-embedding-3-large use correct dimensions (3072) instead of hardcoded 1536
• Fix #13: Nix frontend build - Added frontendDist derivation in flake.nix using buildNpmPackage so nix profile install github:postrv/narsil-mcp#with-frontend works
• Rust security rules - 18 new rules (RUST-004 to RUST-021) covering command injection, transmute, FFI boundaries, TOCTOU, ReDoS, static mut, SSRF, and more
• Elixir security rules - 18 new rules (EX-001 to EX-018) covering atom exhaustion, binary_to_term deserialization, Code.eval injection, Ecto SQL injection, Phoenix XSS, Erlang distribution security
• Migrated from serde_yaml to serde-saphyr - Deprecated serde_yaml replaced with actively maintained, panic-free YAML library
• Custom favicon - Frontend now uses narsil-mcp branding icon instead of default Vite logo
• Dependency security - Updated time to 0.3.47 (RUSTSEC-2026-0009), bytes to 1.11.1 (RUSTSEC-2026-0007)
• Test count increased from 1,611 to 1,763 (+152 tests)

v1.5.x

• Deterministic call graph resolution - Scope-hint propagation disambiguates callee resolution (e.g., App::run() correctly resolves to src/app/mod.rs::run)
• 8 graph analysis fixes - Qualified node keys, hotspot filtering, CFG expression handling, import path parsing
• Nix flake improvements - DRY mkPkg helper, removed unnecessary macOS frameworks, --lib test strategy for sandbox builds

v1.4.x

• SPARQL / RDF Knowledge Graph - Query code intelligence data with SPARQL via Oxigraph
• Code Context Graph (CCG) - 12 tools for standardized, AI-consumable codebase representations with tiered layers (L0-L3)
• Type-aware security analysis - Enhanced taint tracking with type inference and trait implementations
• Multi-language CFG/DFG - Control flow and data flow analysis extended to Go, Java, C#, Kotlin
• Infrastructure as Code scanning - New iac.yaml rules for Terraform, CloudFormation, Kubernetes
• Language-specific security rules - New rules for Go, Java, C#, Kotlin, Bash
• 6 new languages - Erlang, Elm, Fortran, PowerShell, Nix, Groovy
• 90 tools total - Up from 79 with new SPARQL, CCG, and analysis capabilities

v1.2.x

• exclude_tests parameter - 22 tools support filtering out test files
• npm package - Install via npm install -g narsil-mcp

v1.1.x

• Multi-platform distribution - Install via Homebrew, Scoop, npm, Cargo, or direct download
• Configurable tool presets - Minimal, balanced, full, and security-focused presets
• Automatic editor detection - Optimal defaults for Zed, VS Code, Claude Desktop
• Interactive setup wizard - narsil-mcp config init for easy configuration
• 32 language support - Added Dart, Julia, R, Perl, Zig, and more
• Improved performance - Faster startup with background indexing

v1.0.x

• Neural semantic search - Find similar code using Voyage AI or OpenAI embeddings
• Type inference - Infer types in Python/JavaScript/TypeScript without external tools
• Multi-language taint analysis - Security scanning for PHP, Java, C#, Ruby, Kotlin
• WASM build - Run in browser for code playgrounds and educational tools
• 147 bundled security rules - OWASP, CWE, crypto, secrets, Rust, Elixir detection
• IDE configs included - Claude Desktop, Cursor, VS Code, Zed templates

License

Licensed under either of:

• Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Credits

Built with:

• tree-sitter - Incremental parsing
• tantivy - Full-text search
• tokio - Async runtime
• rayon - Data parallelism
• serde - Serialization

Installation

Via Package Managers (Recommended)

macOS / Linux (Homebrew):

brew tap postrv/narsil
brew install narsil-mcp

Windows (Scoop):

scoop bucket add narsil https://github.com/postrv/scoop-narsil
scoop install narsil-mcp

Rust/Cargo (all platforms):

cargo install narsil-mcp

Node.js/npm (all platforms):

npm install -g narsil-mcp
# or
yarn global add narsil-mcp
# or
pnpm add -g narsil-mcp

Nix:

# Run directly without installing
nix run github:postrv/narsil-mcp -- --repos ./my-project

# Install to profile
nix profile install github:postrv/narsil-mcp

# With web visualization frontend
nix profile install github:postrv/narsil-mcp#with-frontend

# Development shell
nix develop github:postrv/narsil-mcp

One-Click Install Script

macOS / Linux:

curl -fsSL https://raw.githubusercontent.com/postrv/narsil-mcp/main/install.sh | bash

Windows (PowerShell):

irm https://raw.githubusercontent.com/postrv/narsil-mcp/main/install.ps1 | iex

Windows (Git Bash / MSYS2):

curl -fsSL https://raw.githubusercontent.com/postrv/narsil-mcp/main/install.sh | bash

Note for Windows users: The PowerShell installer provides better error messages and native Windows integration. It will automatically configure your PATH and check for required build tools if building from source.

From Source

Prerequisites:

• Rust 1.70 or later
• On Windows: Visual Studio Build Tools with "Desktop development with C++"

# Clone and build
git clone git@github.com:postrv/narsil-mcp.git
cd narsil-mcp
cargo build --release

# Binary will be at:
# - macOS/Linux: target/release/narsil-mcp
# - Windows: target/release/narsil-mcp.exe

Feature Builds

narsil-mcp supports different feature sets for different use cases:

# Default build - native MCP server (~30MB)
cargo build --release

# With RDF knowledge graph and CCG tools (~35MB) - SPARQL queries, Code Context Graph
cargo build --release --features graph

# With neural vector search (~32MB) - adds TF-IDF similarity
cargo build --release --features neural

# With ONNX model support (~50MB) - adds local neural embeddings
cargo build --release --features neural-onnx

# With embedded visualization frontend (~31MB)
cargo build --release --features frontend

# Full-featured build with graph + frontend (~40MB)
cargo build --release --features graph,frontend

# For browser/WASM usage
cargo build --release --target wasm32-unknown-unknown --features wasm

Important: The --graph CLI flag requires the binary to be built with --features graph. If you pass --graph to a binary built without this feature, you'll see a warning and SPARQL/CCG tools won't be available. See Troubleshooting below.

For detailed installation instructions, troubleshooting, and platform-specific guides, see docs/INSTALL.md.

Usage

Basic Usage

macOS / Linux:

# Index a single repository
narsil-mcp --repos /path/to/your/project

# Index multiple repositories
narsil-mcp --repos ~/projects/project1 --repos ~/projects/project2

# Enable verbose logging
narsil-mcp --repos /path/to/project --verbose

# Force re-index on startup
narsil-mcp --repos /path/to/project --reindex

Windows (PowerShell / CMD):

# Index a single repository
narsil-mcp --repos C:\Users\YourName\Projects\my-project

# Index multiple repositories
narsil-mcp --repos C:\Projects\project1 --repos C:\Projects\project2

# Enable verbose logging
narsil-mcp --repos C:\Projects\my-project --verbose

# Force re-index on startup
narsil-mcp --repos C:\Projects\my-project --reindex

Full Feature Set

narsil-mcp \
  --repos ~/projects/my-app \
  --git \           # Enable git blame, history, contributors
  --call-graph \    # Enable function call analysis
  --persist \       # Save index to disk for fast startup
  --watch \         # Auto-reindex on file changes
  --lsp \           # Enable LSP for hover, go-to-definition
  --streaming \     # Stream large result sets
  --remote \        # Enable GitHub remote repo support
  --neural \        # Enable neural semantic embeddings
  --neural-backend api \  # Backend: "api" (Voyage/OpenAI) or "onnx"
  --neural-model voyage-code-2 \  # Model to use
  --neural-dimension 3072 \  # Override embedding dimensions (auto-detected per model)
  --graph           # Enable SPARQL/RDF knowledge graph and CCG tools (requires --features graph build)

Note about --graph: This flag enables SPARQL queries and Code Context Graph (CCG) tools, but only if the binary was built with --features graph. The default binary does not include this feature. If you need SPARQL/CCG capabilities, build from source with:

Copy & paste — that's itCopy

cargo build --release --features graph

If you pass --graph to a binary without the feature, you'll see a warning at startup and the server will continue without SPARQL/CCG tools.

Note: Neural embeddings require an API key (or custom endpoint). The easiest way to set this up is with the interactive wizard:

# Run the neural API key setup wizard
narsil-mcp config init --neural

The wizard will:

• Detect your editor (Claude Desktop, Claude Code, Zed, VS Code, JetBrains)
• Prompt for your API provider (Voyage AI, OpenAI, or custom)
• Validate your API key
• Automatically add it to your editor's MCP config

Alternatively, you can manually set one of these environment variables:

• EMBEDDING_API_KEY - Generic API key for any provider
• VOYAGE_API_KEY - Voyage AI specific API key
• OPENAI_API_KEY - OpenAI specific API key
• EMBEDDING_SERVER_ENDPOINT - Custom embedding API endpoint URL (optional, allows using self-hosted models)

Configuration

v1.1.0+ introduces optional configuration for fine-grained control over tools and performance. All existing usage continues to work - configuration is completely optional!

Quick Start

# Generate default config interactively
narsil-mcp config init

# List available tools
narsil-mcp tools list

# Apply a preset via CLI
narsil-mcp --repos ~/project --preset minimal

Automatic Editor Detection

narsil-mcp detects your editor and applies an optimal preset automatically:

Token Savings:

• Minimal preset: 61% fewer tokens vs Full
• Balanced preset: 25% fewer tokens vs Full

Presets

Choose a preset based on your use case:

# Minimal - Fast, lightweight (Zed, Cursor)
narsil-mcp --repos ~/project --preset minimal

# Balanced - Good defaults (VS Code, IntelliJ)
narsil-mcp --repos ~/project --preset balanced --git --call-graph

# Full - All features (Claude Desktop, comprehensive analysis)
narsil-mcp --repos ~/project --preset full --git --call-graph

# Security-focused - Security and supply chain tools
narsil-mcp --repos ~/project --preset security-focused

Configuration Files

User config (~/.config/narsil-mcp/config.yaml):

version: "1.0"
preset: "balanced"

tools:
  # Disable slow tools
  overrides:
    neural_search:
      enabled: false
      reason: "Too slow for interactive use"

performance:
  max_tool_count: 50  # Limit total tools

Project config (.narsil.yaml in repo root):

version: "1.0"
preset: "security-focused"  # Override user preset

tools:
  categories:
    Security:
      enabled: true
    SupplyChain:
      enabled: true

Named repository profiles are useful for multi-repo workspaces:

version: "1.0"
profiles:
  platform:
    repos:
      - ~/src/api
      - ~/src/web
    git: true
    call_graph: true
    persist: true
    preset: balanced

narsil-mcp --profile platform
narsil-mcp config profiles

Priority: CLI flags > Environment vars > Project config > User config > Defaults

Environment Variables

# Select repos/profile
export NARSIL_REPOS=~/src/api,~/src/web
export NARSIL_PROFILE=platform

# Apply preset
export NARSIL_PRESET=minimal

# Enable specific categories
export NARSIL_ENABLED_CATEGORIES=Repository,Symbols,Search

# Disable specific tools
export NARSIL_DISABLED_TOOLS=neural_search,generate_sbom

CLI Commands

# View effective config
narsil-mcp config show

# Validate config file
narsil-mcp config validate ~/.config/narsil-mcp/config.yaml

# List tools by category
narsil-mcp tools list --category Search

# Search for tools
narsil-mcp tools search "git"

# Export config
narsil-mcp config export > my-config.yaml

# List named repository profiles
narsil-mcp config profiles

Learn More:

• Configuration Guide - Full configuration reference
• Installation Guide - Platform-specific installation

Visualization Frontend

Explore call graphs, imports, symbol references, and control flow interactively in your browser.

# Build with embedded frontend
cargo build --release --features frontend

# Run with HTTP server
narsil-mcp --repos ~/project --http --call-graph
# Open http://localhost:3000

Five graph views:

Features:

• Interactive Cytoscape.js graphs with drag, zoom, and double-click drill-down
• Complexity metrics overlay with color coding (green/yellow/orange/red)
• Security vulnerability overlay highlighting taint sources and sinks
• Six layout algorithms (dagre, force-directed, breadthfirst, concentric, circle, grid)
• File tree sidebar with syntax-highlighted code viewer
• URL-driven state (shareable links, browser back/forward)
• Dark mode support
• Node detail panel with code excerpts and navigation to source

Full documentation: See docs/frontend.md for setup, API endpoints, and development mode.

Neural Semantic Search

Find similar code using neural embeddings - even when variable names and structure differ.

# Quick setup with wizard
narsil-mcp config init --neural

# Or manually with Voyage AI
export VOYAGE_API_KEY="your-key"
narsil-mcp --repos ~/project --neural --neural-model voyage-code-2

Supports Voyage AI, OpenAI, custom endpoints, and local ONNX models.

Full documentation: See docs/neural-search.md for setup, backends, and use cases.

Type Inference

Built-in type inference for Python, JavaScript, and TypeScript - no mypy or tsc required.

def process(data):
    result = data.split(",")  # result: list[str]
    count = len(result)       # count: int
    return count * 2          # returns: int

Forgemax Integration (Experimental)

For large-scale agentic workflows, narsil-mcp can be used through Forgemax — a Code Mode MCP gateway that collapses all 90 tools into just 2 (search + execute), reducing tool schema overhead from ~12,000 tokens to ~1,000.

# Install Forgemax
cargo install forgemax

# Run narsil-mcp through Forgemax (uses forge.toml in repo root)
forgemax

The included forge.toml configures narsil-mcp with sensible defaults:

[servers.narsil]
command = "narsil-mcp"
args = ["--repos", ".", "--git", "--call-graph", "--persist", "--watch"]
transport = "stdio"

[sandbox]
timeout_secs = 10
max_heap_mb = 64
max_concurrent = 8

The LLM writes JavaScript that calls through typed proxy objects inside a sandboxed V8 isolate — credentials, file paths, and internal state never leave the host. This approach is particularly useful when working with multiple MCP servers simultaneously, as it keeps the total tool context small and predictable.

MCP Configuration

Add narsil-mcp to your AI assistant by creating a configuration file. Here are the recommended setups:

Claude Code (.mcp.json in project root - Recommended):

Create .mcp.json in your project directory for per-project configuration:

{
  "mcpServers": {
    "narsil-mcp": {
      "command": "narsil-mcp",
      "args": ["--repos", ".", "--git", "--call-graph"]
    }
  }
}

Then start Claude Code in your project:

cd /path/to/project
claude

Using . for --repos automatically indexes the current directory. Claude now has access to 90 code intelligence tools.

Tip: Add --persist --index-path .claude/cache for faster startup on subsequent runs.

For global configuration, edit ~/.claude/settings.json instead. See Claude Code Integration for advanced setups.

Cursor (.cursor/mcp.json):

{
  "mcpServers": {
    "narsil-mcp": {
      "command": "narsil-mcp",
      "args": ["--repos", ".", "--git", "--call-graph"]
    }
  }
}

VS Code + GitHub Copilot (.vscode/mcp.json):

{
  "servers": {
    "narsil-mcp": {
      "command": "narsil-mcp",
      "args": ["--repos", ".", "--git", "--call-graph"]
    }
  }
}

Note for Copilot Enterprise: MCP support requires VS Code 1.102+ and must be enabled by your organization administrator.

Claude Desktop (claude_desktop_config.json):

{
  "mcpServers": {
    "narsil-mcp": {
      "command": "narsil-mcp",
      "args": ["--repos", "/path/to/your/projects", "--git"]
    }
  }
}

Zed (settings.json → Context Servers):

{
  "context_servers": {
    "narsil-mcp": {
      "command": "narsil-mcp",
      "args": ["--repos", ".", "--git"]
    }
  }
}

Note for Zed: narsil-mcp starts immediately and indexes in the background, preventing initialization timeouts.

Claude Code Plugin

For Claude Code users, we provide a plugin with slash commands and a skill for effective tool usage.

Install via Marketplace (Recommended):

# Add the narsil-mcp marketplace
/plugin marketplace add postrv/narsil-mcp

# Install the plugin
/plugin install narsil@narsil-mcp

Or install directly from GitHub:

/plugin install github:postrv/narsil-mcp/narsil-plugin

What's included:

See narsil-plugin/README.md for full documentation.

Ralph Automation Integration

Ralph is a Claude Code automation suite for autonomous code development. When narsil-mcp is available, Ralph gains enhanced code intelligence capabilities:

Setup:

# Install narsil-mcp (Ralph auto-detects it)
cargo install narsil-mcp

# Ralph's quality gates use these tools:
narsil-mcp scan_security --repo <name>
narsil-mcp check_type_errors --repo <name> --path src
narsil-mcp find_injection_vulnerabilities --repo <name>

Ralph gracefully degrades when narsil-mcp is unavailable - all core automation features work without it.

Documentation: See Ralph README for full integration details.

Playbooks & Tutorials

See docs/playbooks for practical usage guides:

Each playbook shows the exact tool chains Claude uses to answer your questions.

WebAssembly (Browser) Usage

narsil-mcp can run entirely in the browser via WebAssembly - perfect for browser-based IDEs, code review tools, or educational platforms.

npm install @narsil-mcp/wasm

import { CodeIntelClient } from '@narsil-mcp/wasm';

const client = new CodeIntelClient();
await client.init();
client.indexFile('src/main.rs', rustSourceCode);
const symbols = client.findSymbols('Handler');

Full documentation: See docs/wasm.md for build instructions, React examples, and API reference.

Troubleshooting

Tree-sitter Build Errors

If you see errors about missing C compilers or tree-sitter during build:

# macOS
xcode-select --install

# Ubuntu/Debian
sudo apt install build-essential

# For WASM builds
brew install emscripten  # macOS

Neural Search API Errors

# Check your API key is set
echo $VOYAGE_API_KEY  # or $OPENAI_API_KEY

# Common issue: wrong key format
export VOYAGE_API_KEY="pa-..."  # Voyage keys start with "pa-"
export OPENAI_API_KEY="sk-..."  # OpenAI keys start with "sk-"

Index Not Finding Files

# Check .gitignore isn't excluding files
narsil-mcp --repos /path --verbose  # Shows skipped files

# Force reindex
narsil-mcp --repos /path --reindex

Memory Issues with Large Repos

# For very large repos (>50K files), increase stack size
RUST_MIN_STACK=8388608 narsil-mcp --repos /path/to/huge-repo

# Or index specific subdirectories
narsil-mcp --repos /path/to/repo/src --repos /path/to/repo/lib

Graph Feature Not Working

If you pass --graph and see a warning like:

WARN: --graph flag was passed but the binary was built without the 'graph' feature.
SPARQL and CCG tools will not be available.

This means you're using a binary that wasn't compiled with the graph feature. To fix:

# Build from source with the graph feature
cargo build --release --features graph

# Or with multiple features
cargo build --release --features graph,frontend

# Then run with --graph
./target/release/narsil-mcp --repos ~/project --graph

Why is this a separate feature? The graph feature adds the Oxigraph RDF database (~5MB additional binary size) which isn't needed for most use cases. It's kept optional to keep the default binary smaller.

How to check if graph is enabled: Look at the startup logs:

• graph=true means the feature is compiled in AND enabled
• graph=false means either the feature isn't compiled, OR --graph wasn't passed