Type Alias RealtimeCheckpointStoreReason

RealtimeCheckpointStoreReason:
    | Exclude<RealtimeCheckpointCompatibilityCode, "compatible">
    | "checkpoint-expired"
    | "credential-screened"
    | "storage-failed"
    | "unsupported-format"

Why a checkpoint was not returned or not persisted. The first six values are exactly the incompatible RealtimeCheckpointCompatibilityCode results, so a discard reason reads in the same vocabulary the delivery gate uses.

unsupported-format is deliberately distinct from invalid-checkpoint (issue #1046): a record written in another store format is not damage, it is a layout this build declines to interpret, and a host that sees a run of them is looking at a version rollback rather than a corrupt database. Realtime cursors are cheap to discard, so the posture stays discard-and-resnapshot; only the reporting distinguishes the two.