Advance compaction while idle now needs the one-hour prompt cache

Compaction is how Claude Code shrinks a long conversation by summarizing earlier parts. While you are idle, Claude Code can work out a compacted version ahead of time.

It now does this only when the prompt cache is the one-hour kind and is still warm, meaning it has not expired yet. The prompt cache keeps recent conversation ready for reuse for a limited time. Before, the decision looked at whether the feature was turned off and how much time had passed.