jig-dev

AI-powered spec-to-task decomposition and execution. Jig transforms high-level feature specifications into structured, executable tasks for AI coding agents.

Install

Quick start (no install)

npx jig-dev init
# or
bunx jig-dev init

Global install

npm install -g jig-dev
# or
bun add -g jig-dev

Then run:

jig init

Usage

Initialize a project

jig init

Jig detects your framework, creates the .jig/ directory, and sets up your project.

Bootstrap from existing code

jig bootstrap

Scans your codebase and generates feature specifications automatically.

Work with specs

jig spec list              # List all specs
jig spec show <name>       # View a spec
jig spec new <name>        # Create a new spec

Decompose and execute

jig decompose <spec>       # Break spec into tasks
jig tasks <spec>           # List tasks for a spec
jig run <spec> <task>      # Execute a task via Claude Code
jig verify <spec> <task>   # Run verification gates
jig status                 # View project status

Cloud sync

jig auth login             # Authenticate
jig sync                   # Sync with cloud

How it works

1. Write specs -- Describe features in markdown with intent, acceptance criteria, and constraints
2. Decompose -- Jig breaks specs into executable tasks with file scopes and verification gates
3. Execute -- Claude Code runs tasks autonomously, guided by rich context
4. Verify -- Automated verification gates confirm each task meets its criteria

Deploying the MCP Server

The hosted MCP server runs on Fly.io at mcp.usejig.dev.

Deploy

fly deploy

Deploys use blue-green strategy: the new instance boots and passes health checks before traffic switches over. Active SSE connections on the old instance are closed gracefully (in-flight requests finish, then transports close).

How graceful shutdown works

1. Fly.io sends SIGTERM to the old instance (forwarded by dumb-init).
2. The server stops accepting new connections.
3. All active MCP transports are closed (SSE streams end cleanly with retry: 3000ms header).
4. In-flight requests have up to 55 seconds to complete (Fly.io kill_timeout is 60s).
5. Clients that lose their SSE stream will auto-reconnect within 3 seconds using the retry interval.
6. If the old session ID is unknown to the new instance, clients re-initialize per the MCP spec (HTTP 404 triggers new InitializeRequest).

Monitoring

# Check server health
curl https://mcp.usejig.dev/health

# View active sessions and uptime
fly ssh console -C "curl -s localhost:8080/health"

# Stream logs during deploy
fly logs

Configuration

Key settings in fly.toml:

• deploy.strategy = "bluegreen" -- zero-downtime traffic switch
• http_service.min_machines_running = 1 -- always-on
• experimental.kill_timeout = "60s" -- drain window before SIGKILL
• http_service.http_options.idle_timeout = 300 -- 5-minute idle timeout for SSE

SSE settings in src/mcp/hosted.ts:

• retryInterval: 3000 -- clients retry SSE connection after 3 seconds
• eventStore: InMemoryEventStore -- enables mid-session SSE resumption via Last-Event-ID
• Keepalive comments every 15 seconds prevent Fly.io proxy timeout

Requirements

• Node.js 18+ or Bun 1.0+
• Claude Code CLI (for task execution)

License

MIT