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 v2.1.311,
Internal ChangesSection of the release
What
When a long conversation is compacted, older messages are replaced with a summary to save space. Claude Code now keeps a running list of the tools used in the session and writes it into the transcript as its own entry, so it is read back when a session is resumed.
The summary created at compaction now takes its list of used tools from this record and includes the names in it. Tool names are cleaned up first, and any that cannot be read are replaced with unreadable-tools-used-before-summary.
Why
After compaction or after resuming a session, Claude still knows which tools were used earlier.
