### One version of a card's content, never changed once written (ADR 0001,
### rule 2): editing appends a revision whose parents are the versions it
### replaces, and a card's current versions are the revisions no other
### replaces. Deleting a card blanks every revision's payload first (ADR 0002,
### rule 2).
class: CardRevision
table: card_revision
database: sync
fields:
  ### The card this is a version of; its revisions go with it.
  card: Card?, relation(onDelete=Cascade, deferred)
  ### The revisions this one replaces: none for a card's first, several when it
  ### resolves a conflict (decided 2026-09-30). Plain ids, since revisions can
  ### arrive in any order.
  parents: List<UuidValue>
  ### Who wrote it: the AuthUser's id (a synced table can't relate to the
  ### server-only AuthUser).
  authorId: UuidValue
  ### The report this revision answers, once reports exist; null otherwise.
  reportId: UuidValue?
  ### The encryption key's id; always null (ADR 0002, rule 6).
  keyId: String?
  ### The content as UTF-8 JSON: {"schemaVersion", "front", "back"}.
  payload: ByteData
  ### The encryption nonce; always null, like keyId.
  nonce: ByteData?
indexes:
  # Deleting a space finds its rows through this index (see studyset.spy.yaml).
  card_revision_space_idx:
    fields: spaceId
  # A card's revisions.
  card_revision_card_idx:
    fields: cardId