feat: core/waveform — peak reduction + ffmpeg region decode

tests/test_utils.py

@@ -540,3 +540,29 @@ def test_audio_extract_ltx2_duration():
                                       duration=frames / fps)
     assert "-t" in cmd
     assert cmd[cmd.index("-t") + 1] == str(frames / fps)
+
+
+# --- waveform peak reduction + region decode ---
+
+def test_peaks_downsamples_to_bucket_count():
+    from core.waveform import peaks
+    import numpy as np
+    samples = np.sin(np.linspace(0, 100, 10000)).astype("float32")
+    p = peaks(samples, buckets=64)
+    assert len(p) == 64
+    assert all(0.0 <= v <= 1.0 for v in p)
+
+
+def test_peaks_empty_returns_zeros():
+    from core.waveform import peaks
+    assert peaks(None, buckets=16) == [0.0] * 16
+    import numpy as np
+    assert peaks(np.zeros(0, dtype="float32"), buckets=8) == [0.0] * 8
+
+
+def test_load_region_samples_bad_path_returns_empty():
+    from core.waveform import load_region_samples
+    import numpy as np
+    out = load_region_samples("/no/such/file.mp4", 0.0, 1.0)
+    assert isinstance(out, np.ndarray)
+    assert out.size == 0