fix(vector): address PR review round 2 — status branching, doc_id guard, doc restore

- _ensure_keyword_payload_indexes: distinguish 400 (schema conflict, warning)
  from other status codes (5xx/network, error) so a transient outage doesn't
  silently leave the collection unindexed.
- build_search_result_from_point: use .get("doc_id") + return None on missing
  instead of KeyError-crashing the search; reverse metadata merge order so
  payload-derived chunk_index/total_chunks win over caller-supplied extras.
- docs/configuration.md: restore the OpenAI/Mistral/Bedrock/Simple provider
  sections + reference-table rows that were dropped in the rebase. Reword
  the "Startup migrations" bullet to describe what the code actually does
  (no sampling — full scroll, zero writes when clean). Add operator note
  about the SemanticSearchResult.id TypeError path.
- tests: pytest.approx for float equality (Sonar python:S1244); coverage
  for non-400 → ERROR, payload={doc_id: None}, and missing doc_id key.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/unit/search/test_search_result.py

@@ -162,6 +162,14 @@ def test_build_search_result_from_point_returns_none_when_payload_missing():
     assert build_search_result_from_point(point) is None
 
 
+@pytest.mark.unit
+def test_build_search_result_from_point_returns_none_when_doc_id_missing():
+    """A payload without a doc_id key is skipped instead of raising KeyError."""
+    point = _make_point(point_id="p-bad", payload={"doc_type": "note"})
+
+    assert build_search_result_from_point(point) is None
+
+
 @pytest.mark.unit
 def test_build_search_result_from_point_note_payload():
     """Note-type payload populates the SearchResult fields without metadata extras."""
@@ -187,7 +195,7 @@ def test_build_search_result_from_point_note_payload():
     assert sr.doc_type == "note"
     assert sr.title == "Hello"
     assert sr.excerpt == "world"
-    assert sr.score == 0.91
+    assert sr.score == pytest.approx(0.91)
     assert sr.chunk_start_offset == 0
     assert sr.chunk_end_offset == 100
     assert sr.chunk_index == 0
@@ -257,21 +265,34 @@ def test_build_search_result_from_point_deck_card_metadata():
 
 @pytest.mark.unit
 def test_build_search_result_from_point_merges_metadata_extras():
-    """metadata_extras override/augment the helper's computed metadata dict."""
+    """metadata_extras augment the helper's computed metadata dict.
+
+    Common fields (chunk_index, total_chunks) win over caller-supplied
+    extras to keep them tied to the actual point.
+    """
     point = _make_point(
         point_id="p-4",
-        payload={"doc_id": "1", "doc_type": "note"},
+        payload={
+            "doc_id": "1",
+            "doc_type": "note",
+            "chunk_index": 3,
+            "total_chunks": 9,
+        },
     )
 
     sr = build_search_result_from_point(
-        point, metadata_extras={"search_method": "bm25_hybrid_rrf"}
+        point,
+        metadata_extras={
+            "search_method": "bm25_hybrid_rrf",
+            # Caller tries to override a common field — should be ignored.
+            "chunk_index": "should-be-overwritten",
+        },
     )
 
     assert sr is not None
     assert sr.metadata["search_method"] == "bm25_hybrid_rrf"
-    # Common fields still present
-    assert "chunk_index" in sr.metadata
-    assert "total_chunks" in sr.metadata
+    assert sr.metadata["chunk_index"] == 3
+    assert sr.metadata["total_chunks"] == 9
 
 
 @pytest.mark.unit

tests/unit/vector/test_qdrant_client.py

@@ -103,6 +103,32 @@ async def test_ensure_keyword_payload_indexes_logs_400_as_warning(mocker, caplog
     assert "different schema" in warnings[0].getMessage()
 
 
+@pytest.mark.unit
+async def test_ensure_keyword_payload_indexes_logs_non_400_as_error(mocker, caplog):
+    """A non-400 status from create_payload_index escalates to ERROR.
+
+    A 5xx response (e.g., Qdrant temporarily unavailable) should not be
+    silently downgraded to a warning the way a 400 schema-conflict is.
+    The loop still continues so the remaining fields get attempted.
+    """
+    client = mocker.AsyncMock()
+    client.create_payload_index.side_effect = [
+        _make_unexpected(500, b'{"status":{"error":"internal server error"}}'),
+        None,
+        None,
+    ]
+
+    with caplog.at_level("ERROR", logger="nextcloud_mcp_server.vector.qdrant_client"):
+        await _ensure_keyword_payload_indexes(client, "test-collection")
+
+    assert client.create_payload_index.await_count == len(_KEYWORD_PAYLOAD_FIELDS)
+    errors = [r for r in caplog.records if r.levelname == "ERROR"]
+    assert len(errors) == 1
+    msg = errors[0].getMessage()
+    assert "500" in msg
+    assert "internal server error" in msg
+
+
 # ---------------------------------------------------------------------------
 # _backfill_doc_id_to_string
 # ---------------------------------------------------------------------------
@@ -231,3 +257,27 @@ async def test_backfill_handles_none_payload(mocker):
         points=[2],
         wait=True,
     )
+
+
+@pytest.mark.unit
+async def test_backfill_handles_payload_with_explicit_none_doc_id(mocker):
+    """A payload of {doc_id: None, ...} is skipped just like payload=None."""
+    client = mocker.AsyncMock()
+    # Build the record manually to distinguish payload=None from payload={"doc_id": None}.
+    point_with_explicit_none = SimpleNamespace(
+        id=1, payload={"doc_id": None, "doc_type": "file"}
+    )
+    client.scroll.side_effect = [
+        ([point_with_explicit_none, _record(2, 99)], None),
+    ]
+
+    await _backfill_doc_id_to_string(client, "test-collection")
+
+    # Only the int doc_id at point 2 was rewritten; the explicit-None payload was skipped.
+    assert client.set_payload.await_count == 1
+    client.set_payload.assert_awaited_with(
+        collection_name="test-collection",
+        payload={"doc_id": "99"},
+        points=[2],
+        wait=True,
+    )