Replay verification
recheckTranscript verifies an action-label permutation, re-simulates canonical actions through a deterministic reducer, and compares the recorded terminal summary with the replayed result.
Transcript inputs
The header records the level, seed, wire-to-canonical permutation, final status, stars, action count, and optional transcript visibility. Visibility is full or seat:<id>; omission retains full-view compatibility. Each action records both its externally visible wire id and canonical reducer id plus optional coordinates, index, boardId, zoneId, seat, a declarative targets tuple, or non-negative integer tick.
const result = recheckTranscript(reducer, header, transcriptActions);
if (!result.ok) console.error(result.problems);Action labels must use the exact one-based form Action N. For each entry, the checker parses both labels and verifies:
header.perm[wireNumber - 1] === canonicalNumber - 1A bad mapping is reported but does not prevent canonical re-simulation, allowing one pass to reveal both permutation and outcome problems.
Re-simulation
The checker initializes the reducer with the recorded level and seed, then submits canonical actions in array order. Optional x, y, index, boardId, zoneId, seat, and targets fields are copied when present. The first rejected action stops replay and adds its number, id, and error message to the problem list.
Ticks must be monotonic. Omitted ticks continue the preceding tick, starting at zero. Pass applyEmptyTick as the fourth argument when scheduled product systems must advance through gaps:
recheckTranscript(reducer, header, actions, {
applyEmptyTick: (state, tick) => advanceScheduledSystems(state, tick),
});Without that callback, an empty tick is an identity step.
After replay it compares:
- status;
- stars, normalizing absent values to
null; and hud.actionsUsed.
The returned replayed summary is available whether verification succeeds or fails.
What it does not verify
This helper does not authenticate a transcript, check session ownership, compare every intermediate event or seat-scoped observation, or prove that the recorded level definition has not changed. Products should version or hash content and use server-side signatures when those properties matter.
Per-level run seeds
runLevelSeed(sessionSeed, levelIndex) derives a deterministic unsigned 32-bit seed for each level in a multi-level run. Level indices are zero-based. Keep their ordering stable; inserting a level changes the derived seeds of later levels unless the product stores an explicit level identity mapping.
Compatibility rule
A transcript is replayable only with compatible reducer logic, content, action ids, and randomness. Version those together. Verification should select the historical adapter before calling this helper rather than replaying old data through current rules.
Zonoid example
When a Zonoid scored session finishes, the server stores the level version, seed, action-label permutation, canonical action log, and terminal summary. Before a result reaches the official benchmark, Zonoid selects the matching universal reducer and re-simulates the transcript with this SDK helper. A desync, rejected action, altered permutation, or forged star count is reported instead of being accepted as a leaderboard result.