test: cover role extractor helper fallbacks

services/analysis-engine/tests/test_roles.py

@@ -86,6 +86,43 @@ def test_role_extractor_basic() -> None:
     assert verse_graph[0]["handoff_to"] == []
 
 
+def test_role_extractor_prefers_first_detected_chord_on_ties() -> None:
+    """Ensure public role extraction keeps the first detected chord on ties."""
+    audio_features = {
+        "stems": {
+            "bass": np.ones(100, dtype=np.float32),
+            "other": np.ones(100, dtype=np.float32),
+        },
+        "sr": 10,
+    }
+
+    with (
+        patch("bandscope_analysis.chords.chord_recognizer.ChordRecognizer") as recognizer_cls,
+        patch("bandscope_analysis.ranges.pitch_tracker.PitchTracker") as tracker_cls,
+    ):
+        tracker_cls.return_value.track.return_value = {
+            "lowest_note": "C2",
+            "highest_note": "C3",
+        }
+        recognizer_cls.return_value.recognize.side_effect = [
+            [{"chord": "A"}, {"chord": "B"}, {"chord": "A"}, {"chord": "B"}],
+            [{"chord": "D"}, {"chord": "C"}, {"chord": "C"}],
+        ]
+
+        result = RoleExtractor().extract([{"id": "intro"}], audio_features)
+
+    roles_by_id = {role["id"]: role for role in result["topologies"][0]["active_roles"]}
+    assert roles_by_id["bass-guitar"]["harmony"]["chord"] == "A"
+    assert roles_by_id["lead-vocal"]["harmony"]["chord"] == "C"
+
+
+def test_extract_without_audio_features_sets_extraction_notes() -> None:
+    """Ensure extraction without audio features still reports computed handoff notes."""
+    result = RoleExtractor().extract([{"id": "intro"}])
+
+    assert "computed handoffs" in result["extraction_notes"]
+
+
 def test_role_extractor_empty() -> None:
     """Test extractor with empty sections list."""
     extractor = RoleExtractor()