What is SigMap?

SigMap extracts a compact signature map of your entire codebase — function names, class hierarchies, exported types, interfaces — and writes it to .github/copilot-instructions.md automatically.

Every AI coding assistant (GitHub Copilot, Claude, Cursor, Windsurf, Gemini) reads that file as its first-message context. Without it, the AI starts each session knowing nothing about your project. With SigMap, it starts with everything.

Before SigMap:  "I don't know your codebase structure — can you share some files?"
After SigMap:   "I can see your AuthService, UserRepository, 47 API routes …"

A 50,000-line TypeScript monorepo → ~3,800 tokens of pure signatures — 97% reduction, zero information loss.

✨ Features

🔄 Auto-regeneration on startup

The extension checks your context file every time VS Code starts and every 60 seconds while it's running. If the file is missing or stale, you're immediately notified.

📊 Live health grade in the status bar

A persistent status bar item shows your context health at a glance — no need to dig into files.

Click the status bar item to trigger an instant regeneration.

🔔 Stale context notifications

If your context hasn't been refreshed in over 24 hours, SigMap pops up a smart notification with a one-click Regenerate button — or you can dismiss it permanently per workspace.

⚡ One-command regeneration

Run SigMap: Regenerate Context from the Command Palette and watch the terminal produce a fresh context file in seconds.

🔒 Secret scanning built-in

SigMap scans every signature before writing. If an AWS key, GitHub token, DB connection string, or Stripe key is detected in a function signature, it's automatically redacted — never leaks into your context file.

🗺 MCP server support

SigMap ships with a built-in Model Context Protocol (MCP) server for Claude and Cursor, exposing three tools:

• read_context — full or per-module signature map
• search_signatures — keyword search across all signatures
• get_map — import graph, class hierarchy, or route table

🌐 21 Language Support

🚀 Quick Start

Step 1 — Install the sigmap CLI

npm install -g sigmap

Or use it without installing:

npx sigmap

Step 2 — Generate your first context file

Open your project in VS Code, then open the Command Palette (⇧⌘P / Ctrl+Shift+P) and run:

SigMap: Regenerate Context

This creates .github/copilot-instructions.md in your workspace root.

Step 3 — Done

GitHub Copilot automatically picks up .github/copilot-instructions.md. Claude, Cursor, Windsurf and Gemini also read it when configured. Your AI assistant now knows your entire codebase.

Tip: Commit .github/copilot-instructions.md to your repo so every team member and CI run benefits.

🔧 Requirements

The extension automatically detects gen-context.js in your workspace root. If installed globally, set sigmap.scriptPath in settings.

⚙️ Extension Settings

Access via File → Preferences → Settings → search for SigMap, or edit settings.json directly.

Example settings.json:

{
  "sigmap.scriptPath": "/Users/you/.npm-global/lib/node_modules/sigmap/gen-context.js"
}

🖥 Commands Reference

Open the Command Palette (⇧⌘P / Ctrl+Shift+P) and type SigMap:

🏗 How It Works

┌─────────────────────────────────────────────────────────┐
│                      Your codebase                       │
│  src/auth.ts  src/api/*.go  lib/models.py  ...          │
└─────────────────┬───────────────────────────────────────┘
                  │  21 language extractors (regex, zero deps)
                  ▼
┌─────────────────────────────────────────────────────────┐
│              Signature map (function names,              │
│              class hierarchy, exported types)            │
│                 ~3,800 tokens  ←  97% smaller            │
└─────────────────┬───────────────────────────────────────┘
                  │  secret scan → token budget → format
                  ▼
        .github/copilot-instructions.md
                  │
          ┌───────┴────────┐
          ▼                ▼
   GitHub Copilot    Claude / Cursor
   Gemini / Windsurf   (via MCP server)

The extractors use only regex and string operations — no AST parser, no npm install, runs in under 1 second on most codebases.

📈 Token Reduction in Practice

Token counts estimated at 4 chars/token (standard approximation).

🤝 AI Tool Integration

GitHub Copilot

No configuration needed. Copilot reads .github/copilot-instructions.md automatically in every chat and inline suggestion.

Claude (claude.ai / Claude Code)

Append to CLAUDE.md by adding to your config:

{ "outputs": ["claude"] }

Cursor

Add .cursorrules output:

{ "outputs": ["cursor"] }

Windsurf

Add .windsurfrules output:

{ "outputs": ["windsurf"] }

MCP server (Claude / Cursor)

node gen-context.js --mcp

Exposes read_context, search_signatures, get_map over stdio JSON-RPC.

🔍 Companion: Repomix

SigMap is designed to work alongside Repomix (15K ⭐):

Use SigMap for every session. Reach for Repomix when you need full file content.

🐛 Troubleshooting

Status bar shows "no context" → Run SigMap: Regenerate Context. If it fails, check that Node.js 18+ is installed: node --version

"gen-context.js not found" warning → Either run npm install -g sigmap or set sigmap.scriptPath in VS Code settings to the absolute path.

Context file is generated but Copilot doesn't seem to use it → The file must be at .github/copilot-instructions.md in your workspace root. Check File → Open Folder opened the right directory.

Grade is always "A" even on a stale file → gen-context.js --health --json may not be available in older versions. Upgrade: npm update -g sigmap

Want to exclude files from the context? → Create .contextignore in your project root (gitignore syntax). Example:

node_modules/
*.test.ts
dist/

📦 Related Resources

🤗 Contributing

Contributions welcome! To add a new language extractor:

1. Fork the sigmap repo
2. Add src/extractors/{language}.js following the extractor contract in CONTRIBUTING.md
3. Add fixture + expected output in test/
4. Submit a PR