Checkpoints and retry

Vishnu keeps a small, in-memory ring of named checkpoints for each running world. Save one at a meaningful moment; the built-in Retry action restores that simulation state. The most recent checkpoint with a name replaces its previous one, and only the eight newest names are retained.

In the Acorn starter, import system and add this rule to the cartridge’s rules array:

TS

const saveOpening = system({
  id: "acorn.save-opening",
  version: 1,
  reads: [],
  writes: [],
  run(context) {
    if (context.clock.tick === 0) context.checkpoint("opening");
  },
});

The first simulation tick records opening. Players can choose Retry from opening in the game’s actions. Checkpoints are runtime snapshots, not published save files; use a new name for each milestone you want to keep.

TERMINAL

vishnu check && vishnu test && vishnu build