Execution contracts

import { run } from 'captar';
 
const result = await run(
  'repair',
  {
    limits: { durationMs: 30_000, resources: { 'db.writes': 100 } },
    outcome: { verified: { equals: 1 } },
  },
  async (execution) => {
    const reservation = execution.reserve('db.writes', 1);
    // Await your database operation here.
    execution.commit(reservation);
    execution.metric('verified', 1);
  }
);

reserve checks committed plus reserved usage before admitting work. commit records actual usage; an actual amount above the ceiling is reported, not silently clamped. release returns unused reserved capacity. consume and its alias count immediately charge resource usage.

Use metric(name, value) for outcome assertions (min, max, equals). Missing required metrics fail the outcome. checkpoint(name, value) records application progress; it does not make the database write and receipt save atomic.

durationMs aborts execution.signal. Underlying operations must honor cancellation; the library cannot preempt arbitrary JavaScript or roll back completed effects. A receipt captured at a deadline may retain reservations for in-flight work.

Only guarded operations count. Resource names and estimated amounts are supplied by your application. Budgets apply to each execution, not to every process in a fleet.