Compaction measures reclaimable space and can skip low-yield runs

What

Compaction is when Claude Code shrinks the saved history of a long conversation so it keeps fitting. The saved history is called the transcript. This release adds a measure of how much a compaction would actually free, and uses it:

• reclaimableBytes: a compaction plan now works out how many bytes it would reclaim.
• skipLowYieldCompact: a new check that runs before background compaction carries out a plan. It receives reclaimableBytes and can abort when the compaction would reclaim little.
• Transcript loading: when a compacted transcript is loaded, the loader now returns scan details. These are whether it kept all rows (preserved_all_rows) or stopped at a preserved boundary, the offset it kept from, the bytes of earlier metadata, and how long the scan took in milliseconds.
• After a resume (picking up an earlier conversation), it also reports keptRowsNotLoaded.

Why

In practice, background compaction can now be skipped when it would free very little space instead of always running. The scan details are mostly diagnostics for resuming and compacting conversations.