Claude Code echoes /compact's stdout ("Not enough messages to compact.")
as a synthetic assistant message and as the result text, so a failed
compaction showed a bare "Context compaction failed" divider followed by
a reply. The Claude adapter now drops both for /compact turns and puts
the reason (compact_error, or the result text when Claude never reported
the compaction) on the failed compaction item's summary. The divider
shows that reason in the error style on web and mobile.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>