phase: 96_oneshot_resilience

All checks complete. Final report:

**Phase 96 (one-shot resilience) — final verification pass, all green** (all 4 task files already in `complete/`; verified the working-tree implementation against the design)

- `LLMClient.chat()` empty-content retry (D1–D3) via `_chat_once` + `_EmptyContentError` (carries `finish_reason`), under `BOR_LLM_RETRIES`/`BOR_LLM_RETRY_DELAY` — verified in diff
- `missing_folder_summaries()` + `generate_folder_summaries(only_missing=…)` — verified; `folder_summary_table_empty` deleted, both sync gates switched to the gap probe
- `.env.example` comments updated (chat-turn stream + one-shot summary calls)

**Test / lint / coverage results**
- `uv run pytest --cov=app --cov-report=term-missing` → **1988 passed**, coverage **99%** (gate >90%)
- `uv run pytest tests/e2e/test_oneshot_llm_retry.py -v --no-cov` → **2 passed** (isolated)
- Regressions, each isolated: `test_ls_tree_drilldown` 3 passed, `test_sync_button` 3 passed, `test_local_directory_sources` 3 passed, `test_llm_retry` 4 passed
- `uv run ruff check . && uv run pyright` → clean (0 errors)

**Completion criteria:** retry-then-recover unit-pinned ✓ · exhaustion + `BOR_LLM_RETRIES=0` byte-identical ✓ · streaming path untouched ✓ · gap-fill both sync paths, other rows byte-identical incl. `updated_at` ✓ · no-gap zero-burn ✓ · phase E2E green ✓ · regression E2Es green ✓ · full suite + >90% + lint/types ✓ · no completed-phase behavior change (full suite green) ✓. Commit left to the harness per executor rules (working tree, 16 files).

**Deviations:** none. **Next pending phase:** `97_kb_tree_catalog`.

tests/unit/test_sync_button.py

@@ -785,11 +785,19 @@ def _patch_sync_seams(
     monkeypatch.setattr(sync_api, "regenerate_overview", fake_overview)
 
     async def fake_folder_summaries(
-        db: object, llm: object, *, skip: bool = False
+        db: object,
+        llm: object,
+        *,
+        skip: bool = False,
+        only_missing: bool = False,
     ) -> dict[str, int]:
         return {"generated": 0, "failed": 0, "pruned": 0}
 
     monkeypatch.setattr(sync_api, "generate_folder_summaries", fake_folder_summaries)
+    # Phase 96 (task 03): the unchanged-walk gap probe is DB-free in
+    # these state-machine tests — no gap, so the folder step stays
+    # skipped exactly as before the gate change.
+    monkeypatch.setattr(sync_api, "missing_folder_summaries", lambda session: [])
 
     class _DummySession:
         def close(self) -> None: