Store-v2 candidate construction and publication. Online callers build the candidate against a frozen frontier while the Writer journals later mutations, catch up in bounded rounds while admission remains open, and fence only the final small delta and atomic epoch switch. The source remains pinned and never loses bytes to make candidate space. Offline publication is verified by an independent Store-v2 replay; online publication fully validates the candidate before the fence, validates every tail mutation while appending it, and verifies the published authority before returning.