Are Packed and Dedicated blob payloads copied during compaction?

[shikhar-goenka-hg]

The blob guide says large payloads live in separate .blob files "that are referenced rather than re-copied, so these operations don't rewrite the heavy bytes", naming compaction as one of those operations. The Blob v2 blog post says Dedicated blobs are "isolated from the table-level rewrite/compaction path".

Measuring on pylance 9.0.0 and 11.0.0b1, both Packed and Dedicated payloads look like they are copied. Starting from two fragments holding 1 MB (Packed) and 8 MB (Dedicated) values, compact_files writes fresh .blob files under the compacted data file and reassigns blob_id, and total sidecar bytes double (18,874,368 to 37,748,736, before old versions are cleaned up). Only External descriptors carry through unchanged, with the referenced file untouched.

Two questions:

1. Is copying the intended behaviour for all Lance-managed placements (Inline, Packed, Dedicated), with External being the only placement that survives a rewrite by reference?
2. If so, is cross-file blob reuse something the Object Layer direction in Lance Blob v2 Object Layer Proposal #7174 is expected to enable eventually, or is file-scoped placement a deliberate long-term constraint?

Asking because we store large imaging payloads in blob columns, and we would like to know whether to plan around the copy or expect it to change. Happy to share the measurement script if that helps.