BlobSummary

One blob as the list surface reports it (GET /api/blobs). The list can only ever
contain blobs the caller can read — the gate lives server-side on the same
blob_readable_by_profile predicate the read-through uses, so this shape is a view of
the caller's own blob set, never a discovery oracle.

{
    "blob_id": "8249af2f-dd23-416e-b9c4-6cb13a792190",
    "content_bytes": 0,
    "content_hash": "string",
    "content_type": "string",
    "created": "2019-08-24T14:15:22.123Z"
}