Add tests for detection threshold

tests/test_api_v2/test_api_v2.py

@@ -243,7 +243,7 @@ def test_user_can_load_checkpoint_with_new_targets(
     detector = cast(Detector, api.model.detector)
     classifier_head = cast(ClassifierHead, detector.classifier_head)
 
-    assert api.targets.config == sample_targets.config
+    assert api.targets.config == sample_targets.config  # type: ignore
     assert detector.num_classes == len(sample_targets.class_names)
     assert (
         classifier_head.classifier.out_channels
@@ -399,6 +399,61 @@ def test_process_file_uses_resolved_batch_size_by_default(
     assert captured["batch_size"] == api_v2.inference_config.loader.batch_size
 
 
+def test_detection_threshold_override_changes_process_file_results(
+    api_v2: BatDetect2API,
+    example_audio_files: list[Path],
+) -> None:
+    """User story: users can override threshold in process_file."""
+
+    default_prediction = api_v2.process_file(example_audio_files[0])
+    strict_prediction = api_v2.process_file(
+        example_audio_files[0],
+        detection_threshold=1.0,
+    )
+
+    assert len(strict_prediction.detections) <= len(
+        default_prediction.detections
+    )
+
+
+def test_detection_threshold_override_is_ephemeral_in_process_file(
+    api_v2: BatDetect2API,
+    example_audio_files: list[Path],
+) -> None:
+    """User story: per-call threshold override does not change defaults."""
+
+    before = api_v2.process_file(example_audio_files[0])
+    _ = api_v2.process_file(
+        example_audio_files[0],
+        detection_threshold=1.0,
+    )
+    after = api_v2.process_file(example_audio_files[0])
+
+    assert len(before.detections) == len(after.detections)
+    np.testing.assert_allclose(
+        [det.detection_score for det in before.detections],
+        [det.detection_score for det in after.detections],
+        atol=1e-6,
+    )
+
+
+def test_detection_threshold_override_changes_spectrogram_results(
+    api_v2: BatDetect2API,
+    example_audio_files: list[Path],
+) -> None:
+    """User story: threshold override works in spectrogram path."""
+
+    audio = api_v2.load_audio(example_audio_files[0])
+    spec = api_v2.generate_spectrogram(audio)
+    default_detections = api_v2.process_spectrogram(spec)
+    strict_detections = api_v2.process_spectrogram(
+        spec,
+        detection_threshold=1.0,
+    )
+
+    assert len(strict_detections) <= len(default_detections)
+
+
 def test_per_call_overrides_are_ephemeral(monkeypatch) -> None:
     """User story: call-level overrides do not mutate resolved defaults."""