All tests pass. Here's the summary:

## Test Results

**Bug found and fixed:** `/code/api/threads.ts` line 8 had an intentional test breakage injected — `throw new Error("SELF_HEAL_TEST_BUG: intentional breakage for testing")`. Removed it.

**All features verified working:**

| Feature | Status |
|---|---|
| Page loads, title "Palace Code" | ✅ |
| Thread list renders (14+ threads visible) | ✅ |
| Thread groups (Junwon to reply, Ace is working) | ✅ |
| Time window pill button ("last 1d") | ✅ |
| New chat textarea present | ✅ |
| Detail panel with reply input | ✅ |
| `GET /code/api/threads` | ✅ (was 500, now 200) |
| `GET /code/api/session-tails` | ✅ 200 |
| `POST /code/api/delete-thread` | ✅ 200 |
| `POST /code/api/chat-stream` | ✅ 200 |
| No JS console errors | ✅ |