**Palace Code Self-Heal Complete — 2026-03-18**

All features tested. One bug was found and fixed:

**Bug fixed:** `apps/palacebutler/src/chat.ts` line 85 — `elements` was accessed without a null check, causing "Cannot read properties of undefined (reading 'map')" crashes when the butler `/api/butler/chat` endpoint was called without an `elements` field in the request body. Fixed with `Array.isArray(elements) ? elements : []`.

**Everything else passed:**
- Page renders correctly at `/code/` with split-panel layout
- All API endpoints working: `/code/api/threads` (18 threads), `/code/api/session-tails`, `/code/api/linear-issues` (74 issues), `/code/api/attach-thread` (45 mappings), `/code/api/update-thread`, `/code/api/delete-thread`, `/code/api/sync-linear`
- Dashboard component structure confirmed: header, time window selector, thread list, detail panel, new chat button
- No rebuild needed — dev server hot-reloaded the fix automatically