name: libsupervision description: > libsupervision - Process supervision system. Supervisor manages process tree inspired by s6-svscan. LongRunner handles persistent processes with restart. OneShot handles single-execution tasks. ProcessState tracks process lifecycle. LogWriter manages process logging. Use for service management, process control, and graceful shutdown handling.

libsupervision Skill

When to Use

• Managing long-running service processes
• Implementing process supervision with restart
• Running one-shot initialization tasks
• Handling graceful shutdown across processes

Key Concepts

Supervisor: Manages a tree of processes, handling startup order and shutdown.

LongRunner: Process that restarts automatically on exit (for services).

OneShot: Process that runs once (for migrations, initialization).

ProcessState: Tracks process state transitions (starting, running, stopped).

Usage Patterns

Pattern 1: Create supervision tree

import { Supervisor, LongRunner, OneShot } from "@copilot-ld/libsupervision";

const supervisor = new Supervisor();
supervisor.add(new OneShot("migrate", "npm run migrate"));
supervisor.add(new LongRunner("web", "npm start"));
await supervisor.start();

Pattern 2: Handle signals

process.on("SIGTERM", async () => {
  await supervisor.stop(); // Graceful shutdown
});

Integration

Powers the service supervision system. Used by librc for service management.