cozy-games/packages/move-log/README.md

@cozy-games/move-log

A game-agnostic container for a recorded run of move events. It wraps any game's event stream in a schema-versioned, ordered, timestamped log.

import {
  createMoveLog, serializeMoveLog, deserializeMoveLog, isMoveLog, SCHEMA_VERSION
} from '@cozy-games/move-log'

// `T` is your game's own event vocabulary — supplied by you, unknown to us.
const log = createMoveLog([
  { seq: 1, t: 0, event: { type: 'reveal', r: 0, c: 0 } },
  { seq: 2, t: 50, event: { type: 'flag', r: 1, c: 2 } }
])
// → { schema_version: 1, events: [ { seq, t, event }, ... ] }

const json = serializeMoveLog(log)          // → JSON string
const restored = deserializeMoveLog(json)    // → validated MoveLog, or throws

Shape

field	type	meaning
schema_version	1	the move-log container version
events	MoveEvent<T>[]	ordered, each { seq, t, event }

MoveEvent<T> = { seq: number, t: number, event: T } — the log owns the per-event recording metadata (a strictly increasing seq and a timestamp t), so T stays a pure game payload with no required shape.

deserializeMoveLog round-trips a serialized log with full fidelity (order, timestamps, sequence numbers) and rejects malformed input — bad JSON, missing or wrong-typed fields, or non-monotonic seq — with a clear error, never returning a partially-parsed log.

Invariant: zero game-specific imports

This module must never import a game package (e.g. mnswpr) or any game vocabulary. T is always supplied by the consumer; the log only ever sees opaque payloads. This independence is the whole point — it lets one move-log format serve every game.

The rule is enforced by a dependency-graph guard in test/move-log.test.js (scans the package's source and manifest for game references). Keep it green.