Great change!
Just remember that compaction still consumes usage by reading your ENTIRE chat context, which can be expensive if near the 1M context.
I found it better to start new sessions since Opus 5.5 is so good at refetching context.
We recently added idle compaction to Claude Code!
It now compacts long idle sessions right before the prompt cache expires (~1h). If you come back to it later, it only has to reprocess the summary instead of the entire conversation, which saves you some usage.