@substrat-run/engine-booking

Reservation engine for Substrat — resources, intervals, and capacity. It owns exactly one invariant and nothing else.

It knows nothing about pricing, opening hours, recurrence, cancellation windows, skill levels, or timezones — all of that is vertical policy. It takes absolute instants and compares them; it never does calendar arithmetic.

What it owns

• One invariant: capacity is never exceeded. Concurrent allocations against a resource never exceed its capacity over any overlapping interval — enforced without row locks.
• A hold → confirm lifecycle. A hold is a provisional claim that expires on its own; confirm makes it firm; move, cancel, start, complete, and no-show carry it the rest of the way.
• Attribution comes from the ambient principal, never from the input.
• Every mutation emits a fat event — booking.held, booking.confirmed, booking.moved, booking.completed, … — so consumers never query back.

Install

pnpm add @substrat-run/engine-booking

import {
  bookingManifest,
  createResource,
  holdReservation,
  confirmReservation,
  PERM,
} from '@substrat-run/engine-booking';
import { assertAllowed } from '@substrat-run/kernel';

host.registerModule(bookingManifest);

// The engine registers no `booking/hold` operation: the vertical decides what a
// resource is, what it costs, and when it is bookable — then composes the in-scope
// function inside its own operation, in the same transaction, after its own check.
host.defineOperation('salon/request-slot', async (ctx, input) => {
  assertAllowed(await ctx.check(PERM.hold));
  return holdReservation(ctx, {
    resource: input.chair, // opaque EntityRef — the vertical owns resources
    from: input.from, // absolute instant
    until: input.until,
    holder: input.customer,
  });
});

Documentation

https://substrat.net/engines — the domain model and the capacity invariant, the full operation/permission surface, the event contracts, and how a vertical composes or extends it.

The docs site is the single source of truth; this README deliberately doesn't restate it.

Related packages

• @substrat-run/kernel — the scope-host contract these operations run on
• @substrat-run/contracts — the branded IDs, Money, and manifest schemas in the surface

Status

Pre-release (0.x): surfaces change without notice until the first vertical ships.