Under the hoodTier: how much it should matter to you
1Useful: my rating, 1 to 5
1Signal: worth watching, 1 to 5
CompactionArea: what it touches
Bug FixesKind: in v2.1.300,
Bug FixesSection of the release
What
Compaction is what Claude Code does when a conversation gets too long: it shortens older parts so the session can continue. Some messages are marked to be kept as they are. Claude Code now checks that list and removes any message that no longer exists in the conversation.
When it does this, Claude Code also records how many entries were dropped. It also records how many tool steps were left without their pair. A tool step is a request from Claude to run a tool, matched with the tool's reply.
Why
This helps stop a tool request from being left without its reply, or a reply without its request, after compaction. Mismatched pairs like that can break the conversation.
