Handler registration

Basic usage

lastcall.register(name, handler, options?);

lastcall.register('database', async (ctx) => {
  console.log(`Shutting down because: ${ctx.reason}`);
  await db.disconnect();
});

Options

Option	Type	Default	Description
priority	number	100	Lower = earlier within phase
timeoutMs	number	—	Per-handler timeout
critical	boolean	false	Failure sets exit code to 1
deps	string[]	[]	Handler names that must finish first in the same phase
phase	ShutdownPhase	'cleanup'	Shutdown phase

Unregister

lastcall.unregister('database'); // returns true if removed

Critical handlers

Mark infrastructure handlers as critical so failures are visible to orchestrators:

lastcall.register(
  'database',
  async () => {
    await db.disconnect();
  },
  { critical: true },
);

Timeouts

lastcall.register(
  'slow-service',
  async () => {
    await slow.close();
  },
  { timeoutMs: 5_000 },
);

If the handler exceeds 5 seconds, lastcall logs a clear message and continues shutdown.

Dependencies

Handlers in the deps array must be registered in the same phase. Cross-phase dependencies throw at registration time:

// ❌ throws — drain-job is in 'drain', cleanup-job is in 'cleanup'
lastcall.register('drain-job', fn, { phase: 'drain' });
lastcall.register('cleanup-job', fn, { phase: 'cleanup', deps: ['drain-job'] });

Circular dependencies within a phase throw TopologicalSortError at shutdown time. Catch it via the exported TopologicalSortError class if you need programmatic handling.

Registering a handler while shutdown is in progress throws an error — register everything at startup.

Check shutdown state

if (lastcall.isShuttingDown()) {
  // reject new work
}