X_MUTATOR_CLOCK_MISSING

a mutator declares conflict: 'last-write-wins' and its entity has no number clock column

mutator({ conflict: 'last-write-wins' }), checked at declaration. An entity row in its output has no number updatedAt the server writes (a timestamp() string does not count), or the output carries no entity row at all. Core's resolveConflict could then never prove the local row newer, so the server row would win every time

add updatedAt (a number, epoch ms, written by the server) to the entity, or declare conflict: 'server-wins'. With no entity row in the output: return the entity row from the mutator's output, or declare conflict: 'server-wins'