Quick Start — SigMap

Prerequisites

Before you start

One requirement. That's it.

🟢

Node.js 18 or later

Check with node --version. Install from nodejs.org if needed. No other tools, runtimes, or package managers required.

terminal

$ node --version

v22.11.0 ← v18+ required

Installation

Three steps

No package manager. No build step. Just copy one file into your project.

1

Step 1 of 3

Download gen-context.js

Copy the single-file entry point into the root of your project. No package.json changes needed.

your-project/

$ curl -O https://raw.githubusercontent.com/manojmallick/sigmap/main/gen-context.js

% Total % Received

100 48.2K 100 48.2K ← single file, ~50KB

2

Step 2 of 3

Generate your context file

Run it once. It scans your codebase, extracts signatures from all 21 supported languages, and writes .github/copilot-instructions.md.

your-project/

$ node gen-context.js

[sigmap] scanning 247 files across src/ app/ lib/

[sigmap] extracted 1,842 signatures from 89 files

[sigmap] secret scan: clean (0 findings)

[sigmap] budget: 6,000 tokens target, using 3,847

[sigmap] ✓ wrote .github/copilot-instructions.md

[sigmap] reduction: 82,400 → 3,847 tokens (95.3%)

3

Step 3 of 3

Enable always-on updates

The --setup flag installs a git post-commit hook and starts a file watcher. From now on, every save and every commit automatically regenerates the context file.

your-project/

$ node gen-context.js --setup

[sigmap] ✓ installed .git/hooks/post-commit

[sigmap] ✓ watcher started on src/ app/ lib/

[sigmap] watching for changes... (Ctrl+C to stop)

Verification

What you get

The token report and a structured context file your AI agent reads at every session start.

node gen-context.js --report

╔══════════════════════════════════╗

║ SigMap Token Report ║

╚══════════════════════════════════╝

Input 82,400 tokens (full source)

Output 3,847 tokens (signatures only)

Saved 78,553 tokens (95.3% reduction)

Files scanned 247

Files included 89 (dropped 158 under budget)

Languages TypeScript, Python, Go, CSS

Secrets found 0 (clean)

Output: .github/copilot-instructions.md

.github/copilot-instructions.md (excerpt)

# Code signatures

## src/api/users.ts

export interface User

export class UserService

async findById(id: string): Promise<User>

async create(data: CreateUserDto): Promise<User>

async delete(id: string): Promise<void>

## src/auth/jwt.ts

export function signToken(payload: JwtPayload): string

export function verifyToken(token: string): JwtPayload

...89 more files...

Configuration

Customise the output

Create gen-context.config.json in your project root. All fields optional.

gen-context.config.json

{

"output": ".github/copilot-instructions.md",

"outputs": ["copilot", "claude", "cursor"],

"srcDirs": ["src", "app", "lib"],

"maxTokens": 6000,

"secretScan": true,

"monorepo": false,

"diffPriority": true

}

outputs

string[] — default: ["copilot"]

Write to multiple target files in one run. Supports copilot, claude, cursor, windsurf.

srcDirs

string[] — default: ["src","app","lib","packages","services","api"]

Directories to scan. Relative to project root. Nested paths are scanned recursively up to maxDepth.

maxTokens

number — default: 6000

Token budget for the output file. Files are dropped in priority order when the budget is exceeded.

maxDepth

number — default: 6

Maximum directory depth to recurse into. Increase for deeply nested monorepos.

secretScan

boolean — default: true

Scan extracted signatures for API keys, tokens, passwords, and secrets before writing. Redacts matches automatically.

diffPriority

boolean — default: true

Files changed in recent git commits are prioritised within the token budget. Keeps the most relevant code front-and-center.

monorepo

boolean — default: false

When enabled, generates a separate context file per package in a monorepo, using the package name as the section header.

routing

boolean — default: false

Appends a model routing recommendation section: which AI model tier to use for each file based on its complexity score.

📄

.contextignore

Create a .contextignore file in your project root using the same gitignore syntax to exclude specific paths. This file is compatible with .repomixignore — you can symlink them to share one exclusion list.

All CLI flags