Under the hoodTier: how much it should matter to you
2Useful: my rating, 1 to 5
2Signal: worth watching, 1 to 5
CompactionArea: what it touches
Internal ChangesKind: in v2.1.305,
Internal ChangesSection of the release
What
Compaction is when Claude Code summarizes and shortens a long conversation to free up space. It now records more about how that went.
The full compaction path now reports its result, including the reply, outputTokens (how much text was produced) and stopReason (why the reply ended).
A new ptlAttempts count is recorded. When it is above 0, the summary is built with headTruncated, meaning the start of the conversation was cut. A compaction that had to drop the start is recorded as compact_head_dropped.
The partial compaction path now records whether the summary block was closed, open or absent, whether an unanswered user request was left after the compacted messages (prompt, other_message or none), and the output tokens and stop reason.
Nothing has been read about the gates these run behind.
Why
These are diagnostics rather than new behaviour. One part is visible in practice: when a compaction has to retry and cut the start of a conversation, the summary is now built knowing that the start was dropped.
