oka_artifacts

Content-addressed artifact store with delta chains (ADR-0043): git stores pointers, bytes live here, and the snapshot cadence emerges from measured delta ratios — the "diff → diff… → snapshot" storage shape, with no configuration and no cron.

60-second version

final store = ArtifactStore.forMachine(); // ~/.oka/artifacts
final receipt = store.record(
  File('build/app.dill').readAsBytesSync(),
  name: 'app-dill',
  policy: const DeltaChain(), // rollover at 35% delta ratio, depth 8, every 20
  codec: const ZstdCliCodec(),
);
print(receipt); // app-dill delta    1a2b3c4d5e6f (delta 8211 / full 33554432)

final full = store.materialize(name: 'app-dill', codec: const ZstdCliCodec());
// full.sha256 — identity is the digest; every chain step was hash-verified.

Laws: identical content is a no-op write; every materialization step is hash-verified; an unavailable codec degrades to snapshots loudly (the receipt names it); the store lives outside the visible codebase — a developer's tree gains nothing. Sharing a warm start across clones is opt-in: write an ArtifactPointer (~200 bytes, provenance required) where the binary used to be, and host blobs/<sha> on any static HTTP backend — the digest is the integrity check.

Where to look

• ADR-0043 for the why (and the scoped note vs the 2026-09-28 build-cache decision).
• CLI: dart run bin/oka_artifacts.dart put|materialize|verify|status.
• The first wired consumer: the harness harnessd.jit.dill rebuild lane.