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
RemovedKind: in v2.1.323,
RemovedSection of the release
Unclear It is unclear whether text typed after /compact still reaches the summary by another route.
What
Compaction is when Claude Code summarizes a long conversation so it fits in the model's working space. Compaction used to read custom instructions from what it was given and pass them on to the summary and to hooks. It no longer does.
A hook is a command you set up to run at certain moments. The PreCompact hook, which runs before compaction, now receives no custom instructions. Only instructions the hook sends back are used.
Why
If you add focus text after /compact to steer the summary, check whether your summaries still follow it. Instructions supplied through a PreCompact hook still apply.
Read from
Feature flag
tengu_compact_cache_prefixOff in both readings
The flag server returned off for the account this site reads and for the anonymous baseline. A reading of off cannot rule out a rollout these two readings sit outside of.
This account: off · anonymous baseline: off · compiled default in v2.1.323: on
These values were read against a different version of Claude Code, so treat them as the nearest reading available instead of one taken on this release.
Something disagreesSomething we can check disagrees with this entry, or the writer said they could not settle it.
The writer flagged doubtIt is unclear whether text typed after `/compact` still reaches the summary by another route.
Anthropic's release notes agreeFixed running /compact again, or after a command such as /context, summarizing away a message that Claude had not answered yet
