Core — Operations & History

src/core/operations/operations.ts — createTransaction(doc,intent) with insertBlock/deleteBlock, insertInline/deleteInline, applyMarks, commit() → {document, ops, inverses, intent}.

src/core/selection/selection.ts — createCollapsedSelection, createRangeSelection, isCollapsed, mapSelectionThroughOps.

src/core/history/history.ts — History with coalescing by time/intent, checkpoints, limit, undo/redo.

src/core/events/index.ts — EventEmitter (beforeChange/afterChange).

See tests/unit/validator.test.js, history usage in editor.