Hello
\",\n config: [\n history(),\n Command.handler(cmdUndo, (ed) => undo({state: ed.state})),\n Command.handler(cmdRedo, (ed) => redo({state: ed.state})),\n ],\n})\n```\n\n## Features / concepts\n\n### Recording\n\nDocument changes (and optional inverted effects) are stored as linked events on a done branch; undo moves them to an undone branch. Adjacent typing/deletes can **join** into one undo step when they occur within `newGroupDelay` and pass `joinToEvent`.\n\n### Pure commands\n\n`undo` / `redo` return `Transaction.Spec | false`. They never dispatch themselves — apply with `state.update` or `editor.dispatch`.\n\n### Opt-out and boundaries\n\n| Mechanism | Effect |\n|-----------|--------|\n| `Transaction.addToHistory.of(false)` | Edit without recording (still maps existing events) |\n| `history.isolate.of(\"before\" \\| \"after\" \\| \"full\")` | Force a group boundary relative to neighbors |\n| `EditorState.readOnly` | Commands return `false` (history may still record if other code applies changes) |\n\n### Custom effects\n\nRegister `history.invertedEffects` providers so non-document effects can be inverted and restored on undo/redo.\n\n### Serialization\n\nInclude `history.field` in the field map for `state.toJSON` / `EditorState.fromJSON` to preserve undo stacks:\n\n```ts\nlet fields = {hist: history.field as EditorState.Field