- Add a fixed-UUID sentinel point written after a successful doc_id
backfill so subsequent restarts retrieve it and short-circuit the
O(N) scroll. Sentinel has no user_id/doc_id/doc_type payload so
production search filters never see it.
- Pre-fetch payload_schema in _ensure_keyword_payload_indexes and
silently skip fields that are already indexed; the "Created KEYWORD
payload index" INFO log fires only on actual creation.
- Narrow stale `int | str` doc_id annotations to `str` across
search/verification.py (BatchVerifier return type, per-verifier
accessible sets, by_type / accessible_by_type / inaccessible
collections); drop the now-redundant `type(d).__name__` prefix in
the dropped-docs log.
- Align the backfill log message with the PR description's
"Running doc_id backfill" promise; add a caller cross-reference to
the wait=True comment.
- Fix _get_file_path_from_qdrant docstring (file_id is str, not numeric).
- Convert legacy `id=1` to `id="1"` in test_search_result.py to match
the SearchResult.id: str annotation.
Three new unit tests cover sentinel-found, sentinel-written, and
skip-existing-index branches; existing backfill tests pass dimension
and explicit retrieve.return_value=[] for the no-sentinel path.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
