Sheetwrite supplies contracts, not a database or endpoint. A PersistenceAdapter loads a schema-versioned WorkbookSnapshot and commits immutable PendingCommit records carrying a stable clientMutationId and baseVersion.
A commit response is applied, duplicate, or conflict. Applied and duplicate acknowledgements advance the server version. A conflict may provide ordered operations since the base or a current snapshot; ambiguous structural or formula conflicts require host UX rather than silent merge.
IndexedDbPendingCommitStorage from @sheetwrite/core/browser can retain optimistic work across reloads. Its typed errors report blocked upgrades, unsupported schemas, quota, transaction, and abort failures. The core continues without durable browser storage when no pending-storage adapter is supplied.
Document snapshots include workbook/sheet data, formula source, formatting, validation, protection metadata, notes, names, filters, and related document state. Selection, scroll position, caret state, search overlays, host read-only policy, and local zoom remain session state.