You'll notice
When compaction runs out of room it now summarizes the whole conversation, truncating the head and retrying, instead of failing.
When reactive compaction's normal ladder of progressively-preserving-fewer-groups runs out of room, it no longer fails outright with exhausted. It now falls back to summarizing the entire conversation, and if that request is still too long, truncates the head of the conversation and retries, up to a bound, before giving up.