Type Alias: WriteRule

WriteRule = boolean | ((entry, field) => boolean | undefined)

Defined in: model/capabilities.ts:35

#256: the write rule takes the cell, because a write names one. Call: capabilities: { edit: (entry, field) => (entry.id === 'fixed' && field === 'end' ? false : undefined) }.

undefined means "no opinion about this cell". The rules in view/capability.ts then answer it, and a roll-up parent's derived cell stays refused. A predicate names one cell out of every (Entry × Field) pair on the page. So no opinion is the answer it gives most of the time.

A bare boolean over that whole space made a consumer restate every library rule to lock one cell. The harness's own first call site opened every derived cell by accident.

undefined reads the same way an Aggregator's does (model/field.ts). A before* handler's reads that way too. A boolean pins every cell, with no fall-through.