Improve error message clarity for sketch compaction

Discord Message

Author: philz42 Channel: #shelley Link: https://discord.com/channels/1405685085923049482/1450334528210993295/1455940977448583308

Correct. No compaction. We tried it when working on sketch and didn’t feel it worked well. (Nor do I find it works well in Claude Code.) I’ll make the error message clearer.