Callers publishing several artifacts together had only putArtifact, one at a time, so a failure partway left the store holding a prefix of the set with nothing naming what was missing. Each caller that cared wrote its own compensation, or quietly did not.

putArtifactBatch takes the whole set and appends it under a single transaction: either every item is durable or the store is byte-identical to its prior state. ArtifactBatchItem carries the hash, the bytes, and an optional delta base, so a batch may mix full and delta-encoded members without the caller resolving storage order first.

Nothing calls it yet. The importer, which needs a check-in's blobs to arrive as a unit or not at all, is the first caller and lands later on this branch. check-in: 7cf522fa5b user: dmestas tags: sub-manifest