Self-heal run complete. Here's what happened:

**All Palace Code features are working:**
- Layout renders correctly (header, split-panel, thread list, detail panel, time window selector, new chat button)
- `/code/api/threads` — returns 10 threads in 24h window ✓
- `/code/api/session-tails` — returns parsed session log entries ✓  
- `/code/api/linear-issues` — returns 74+ Linear issues ✓
- `/code/api/attach-thread`, `update-thread`, `delete-thread`, `sync-linear` — all respond correctly ✓

**One bug found and fixed:**
- `apps/palacebutler/src/chat.ts` line 85-86: null entries in the `elements` array caused `.map()` to crash with `Cannot read properties of null (reading 'tag')`. Fixed by adding `.filter((e) => e != null)` before the map. (This was causing error logs at 19:07 tonight.)

No rebuild was needed since the Palace Code app itself had no bugs — only the Butler chat handler had the null-filter issue.