# Immutable artifact publication > Owner/scope: cross-process immutable publication and descriptor delivery ## Cuetree library cohort The active library is one [Cuetree cohort](/Cuetree/persistence): MDIA, ALBM, ARTS and GNRV. `SnapshotStore` writes immutable files and a manifest of byte lengths and XXH3-64 checksums, then atomically replaces CURRENT only after all four members are durable. Player accepts only the complete, validated cohort named by CURRENT; it never mixes members from different generations. Indexer serves read-only descriptors for the exact validated files. A pending, corrupt or incomplete candidate leaves the previously accepted cohort active. The factual and Player stores each retain only their CURRENT and PREVIOUS complete cohorts after a committed publication; open read-only descriptors remain valid when an older directory is removed. An invalid CURRENT can fall back only to its validated PREVIOUS, never to a directory found by enumeration. See [Cuetree persistence](/Cuetree/persistence). An existing valid Cuetree snapshot is served first at startup, before a new scan publishes anything. The previous snapshot is the sole retained scan input. A missing Cuetree snapshot starts from empty state. ## Publication cadence The [stage owner](/Riff/LATEST/indexer-staging#5-l0-l1-l2-and-common-publication-clock) defines strict L0/L1/L2 barriers. One monotonic clock starts at actual L0 processing and spans Cuetree and MDRG. The first changed complete intermediate batch is due at 30 seconds; later batches are due 60 seconds after the previous successful batch. Entering L1/L2 does not spend an unelapsed first deadline, create a timer or force a phase-boundary flush. At a due completed directory/media/table, handled-failure/failed-skip or analysis-item boundary, publish each changed validated artifact. Unchanged streams retain pointer/generation. Each stream keeps an independent strictly increasing generation. A long item finishes before publication; partial acquisition is never exposed. Overdue deadlines yield one latest batch, not a catch-up burst. Final pipeline completion, including handled optional-analysis failure, immediately flushes remaining changed valid state. Cancellation/systemic failure retains accepted cohorts. Changed Cuetree publications consume TTL. Before authoritative L0 enumeration, retain unvisited previous facts and availability. Successful physical MEDIA/METADATA kind implies completed L1 and its successful stat; FAILEDL1 records completed errors under [source failures](/Riff/LATEST/indexer-source-failures). There is no L1 completion flag, header Boolean or metadata-upgrade pass. L0 cannot publish new playable sources with provisional Media.ID. Old facts for an observed changed binding are retained, but the binding is pending rather than confirmed access to old content. Identity collisions and structural relations validate in every offered cohort. An unchanged pass publishes nothing. Player retains its cohort while validating exact-inode replacements. Optional MDRG failure never blocks factual publication. The shared clock does not combine formats/generations into one transaction.