Under the hoodTier: how much it should matter to you
1Useful: my rating, 1 to 5
2Signal: worth watching, 1 to 5
CompactionArea: what it touches
Internal ChangesKind: in v2.1.281,
Internal ChangesSection of the release
What
Compaction is when Claude Code summarises older parts of a conversation to free up room. For precomputed compaction, the arm fraction and the window source are now worked out from a new facts input instead of directly from mainLoopModel, the model the main conversation uses.
Why
These values no longer depend only on which model is in use.
How sure we are
Something disagreesSomething we can check disagrees with this entry, or the writer said they could not settle it.
The writer flagged doubtThe finding does not say what `facts` contains or whether this changes when compaction happens.
Anthropic's release notes agreeImproved screen-reader output in /mcp: a disabled server is read as "off" instead of "pending"
