Under the hoodTier: how much it should matter to you
2Useful: my rating, 1 to 5
3Signal: worth watching, 1 to 5
CompactionArea: what it touches
Internal ChangesKind: in v2.1.304,
Internal ChangesSection of the release
What
Compaction is when Claude Code shrinks the earlier part of a long conversation into a summary to free up room. New code can now record the names of the tools Claude used before that point. A tool is one of the actions Claude can take, such as reading a file or running a command.
Tool names are gathered from the tool calls made earlier in the conversation, and from any list kept by an earlier summary.
The list can be turned into a plain line in the summary that reads "Tools called before this summary:" followed by the names.
Why
After compaction Claude no longer sees its earlier tool calls in full. A list like this gives it a record of which tools it had already been using, which can help it find those tools again.
