You'll noticeTier: how much it should matter to you
4Useful: my rating, 1 to 5
4Signal: worth watching, 1 to 5
CompactionArea: what it touches
New FeaturesKind: in v2.1.300,
What probably matters to youSection of the release
What
Compaction is when Claude Code shrinks a long conversation into a summary so it keeps fitting in the model's working memory. When a session has been idle, Claude Code could already compact it. It now has a second mode, compact on return, which summarizes the conversation when you come back.
Other compaction changes:
summaries prepared in advance, and compaction that happens in response to a problem, can now be triggered by idle time
a summary prepared in advance is skipped if it no longer fits the conversation
Which mode is used is set by configuration Anthropic sends from its servers.
Why
This changes how room in the conversation is freed up when you return to a session after a break.
