test: cover search no-Lance error path + multi-list RRF (#358)

tests/test_mcp_v2.py

@@ -588,6 +588,25 @@ def test_search_unknown_filter_key_returns_failure(monkeypatch, ladybug_graph) -
     assert "typo_key" in out.message
 
 
+def test_search_no_lance_index_returns_failure_envelope(monkeypatch, ladybug_graph, tmp_path) -> None:
+    """Real search error path (issue #358): every other search test monkeypatches
+    run_search, so the genuine `except Exception` envelope in search_v2 was never
+    exercised. With no Lance vector index present, search returns a structured
+    failure (success=False, non-empty message, no traceback) while the graph-only
+    tools still succeed against the same graph — proving the failure is
+    vector-specific, not a crash."""
+    empty_index = tmp_path / "no-lance-index"
+    empty_index.mkdir()
+    monkeypatch.setenv("JAVA_CODEBASE_RAG_INDEX_DIR", str(empty_index))
+    out = search_v2("ChatService", graph=ladybug_graph)
+    assert out.success is False
+    assert out.message is not None and out.message.strip()
+    # Graph-only tools still work (the failure is vector-specific, not a crash).
+    found = find_v2("symbol", {"role": "CONTROLLER"}, graph=ladybug_graph)
+    assert found.success is True
+    assert found.results
+
+
 def test_search_pushes_nodefilter_into_run_search(monkeypatch, ladybug_graph) -> None:
     """search forwards NodeFilter structural fields into run_search so the filter
     applies BEFORE pagination, not as a post-filter on the already-paginated page

tests/test_search_lancedb.py

@@ -37,6 +37,25 @@ def test_rrf_merge_weights_second_list_by_row() -> None:
     assert by_file["b.java"] > by_file["c.java"]
 
 
+def test_rrf_merge_reinforced_row_across_lists_outranks_singleton() -> None:
+    """Multi-list RRF (issue #358): a row reinforced across two ranked lists
+    accumulates score and outranks a row appearing in only one list. Merging
+    dedups by (filename, range_start, range_end) and orders by summed score —
+    the core of multi-table fused ranking, previously covered only for the
+    weighted two-list case."""
+    list_a = [{"filename": "a.java", "range_start": 1, "range_end": 5}]
+    list_b = [{"filename": "a.java", "range_start": 1, "range_end": 5}]  # same key, distinct row
+    list_c = [{"filename": "z.java", "range_start": 9, "range_end": 99}]  # singleton, rank 0
+    merged = _rrf_merge([list_a, list_b, list_c], k=60)
+    by_file = {m["filename"]: float(m["_rrf_score"]) for m in merged}
+    # 'a.java' (rank 0 in two lists) sums two contributions; 'z.java' only one.
+    assert by_file["a.java"] > by_file["z.java"]
+    # The two a.java entries collapse to one (dedup by row key).
+    assert len(merged) == 2
+    # Highest summed score first.
+    assert merged[0]["filename"] == "a.java"
+
+
 def test_java_enriched_columns_include_symbol_identity_fields() -> None:
     assert "symbol_id" in JAVA_ENRICHED_COLUMNS
     assert "metadata" in JAVA_ENRICHED_COLUMNS