@bimetal/kanban-data

Kanban-domain event-sourcing, built on @bimetal/event-sourcing.

Board-as-Aggregate. The whole board — columns, cards, and their ordering — is ONE aggregate. Its invariants are hard, enforced in the aggregate's handle, not as soft rules:

• Column ordering is the columns array order.
• Per-column WIP limits (column.wipLimit) reject creates/cross-column moves that would overflow — surfaced as a DataValidationError, never an emitted event.

T = Board, so the generic AggregateState<Board> carries the board as a single entity keyed by its boardId; every event's entityId is the boardId, and card/column identity lives in the payload. Concurrency is therefore board-granular (the consistency boundary the WIP invariant requires).

Whole-board undo. The board is a singleton root — created once, mutated by card/column facts, never deleted. Each mutation pushes the prior whole-board snapshot onto the undo stack; undo(boardId) reverts to it via a BoardReverted fact. No previous fields, no LWW, no conflict resolver (architecture-tested).

import { createKanbanStore, createBoard, createCard, moveCard } from '@bimetal/kanban-data';

const store = createKanbanStore();
await store.dispatch(createBoard({
  id: 'b1',
  columns: [
    { id: 'todo',  title: 'Todo',  wipLimit: null, cardIds: [] },
    { id: 'doing', title: 'Doing', wipLimit: 2,    cardIds: [] },
    { id: 'done',  title: 'Done',  wipLimit: null, cardIds: [] },
  ],
  cards: {},
}));
await store.dispatch(createCard('b1', 'todo', { id: 'c1', title: 'Write spec' }));
await store.dispatch(moveCard('b1', 'c1', 'doing', 0));
await store.undo('b1'); // card back in 'todo'

The dispatch loop, idempotency, snapshots, concurrency checks and live cross-instance subscription are all inherited from the generic schicht unchanged — this package adds only the board fold, invariants, and queries.