You'll noticeTier: how much it should matter to you
2Useful: my rating, 1 to 5
2Signal: worth watching, 1 to 5
CompactionArea: what it touches
ImprovementsKind: in v2.1.317,
ImprovementsSection of the release
What
Compaction is what Claude Code does when a conversation gets too long: it summarises older parts and keeps some recent messages as they are. Some messages carry attached instructions, which are extra text Claude Code adds alongside a message to guide Claude.
When compaction happens in response to a conversation running out of room, Claude Code now drops instruction attachments that come before a certain point in the kept messages. It keeps the ones at or after that point. Before, every kept message went through unchanged.
Why
The same instructions no longer appear twice after compaction, so they take up less of the room Claude has for the conversation.
