fix(media): reject no-audio-track files + purge poisoned waveform cache (#150)

crates/opentake-media/src/decode/pcm.rs

@@ -147,6 +147,12 @@ pub fn extract_pcm(path: &Path, spec: &PcmSpec, range: Option<(f64, f64)>) -> Re
     if !status.success() && raw.is_empty() {
         return Err(MediaError::no_track("audio", path));
     }
+    // ffmpeg can exit 0 with empty stdout when metadata says audio exists but
+    // no decodable samples: treat as no audio track so the waveform cache
+    // isn't poisoned with all-1.0 silence.
+    if raw.is_empty() {
+        return Err(MediaError::no_track("audio", path));
+    }
 
     let samples = raw_to_mono_f32(&raw, spec);
     Ok(PcmBuffer {

crates/opentake-media/src/waveform/store.rs

@@ -34,6 +34,11 @@ pub fn load_waveform(cache_root: &Path, key: &str) -> Option<Vec<f32>> {
     while let Ok(v) = cursor.read_f32::<LittleEndian>() {
         out.push(v);
     }
+    // Reject poison files: every bucket == 1.0 silence is what an older build
+    // cached when extract_pcm returned an empty Vec. Force regeneration.
+    if !out.is_empty() && out.iter().all(|&v| v == 1.0) {
+        return None;
+    }
     Some(out)
 }
 
@@ -97,6 +102,26 @@ mod tests {
         assert!(load_waveform(dir.path(), "bad").is_none());
     }
 
+    #[test]
+    fn load_all_ones_poison_cache_is_none() {
+        // An older build cached all-1.0 buckets when extract_pcm returned an
+        // empty Vec for a "silent" file; treat such a file as poison so the
+        // waveform is regenerated instead of rendered as a flat green band.
+        let dir = tempfile::tempdir().unwrap();
+        save_waveform(dir.path(), "poison", &[1.0f32; 8]).unwrap();
+        assert!(load_waveform(dir.path(), "poison").is_none());
+    }
+
+    #[test]
+    fn load_mixed_values_with_some_ones_is_kept() {
+        // A real waveform whose peaks happen to reach 1.0 must NOT be discarded;
+        // only an all-1.0 file is poison.
+        let dir = tempfile::tempdir().unwrap();
+        let samples = vec![1.0f32, 0.5, 1.0, 0.0];
+        save_waveform(dir.path(), "real", &samples).unwrap();
+        assert_eq!(load_waveform(dir.path(), "real").unwrap(), samples);
+    }
+
     #[test]
     fn little_endian_byte_layout_is_fixed() {
         let dir = tempfile::tempdir().unwrap();

crates/opentake-media/tests/ffmpeg_integration.rs

@@ -216,6 +216,34 @@ fn extract_pcm_no_audio_track_errors() {
     );
 }
 
+#[test]
+fn extract_pcm_empty_stdout_errors_not_silent_buffer() {
+    // Regression for the "ffmpeg exits 0 but emits no PCM" case: a range window
+    // entirely past the media end seeks past EOF, so ffmpeg succeeds yet writes
+    // zero bytes. extract_pcm must surface NoTrack rather than return an empty
+    // buffer — an empty buffer downstream poisons the waveform cache with an
+    // all-1.0 flat band.
+    if !ffmpeg_available() {
+        return;
+    }
+    let dir = tempfile::tempdir().unwrap();
+    let av = dir.path().join("av.mp4");
+    if !make_av(&av) {
+        return;
+    }
+    let spec = PcmSpec {
+        sample_rate: 16_000,
+        channels: 1,
+        format: PcmFormat::F32,
+    };
+    // The clip is ~2 s long; ask for [5.0, 6.0) → past EOF → empty stdout.
+    let res = extract_pcm(&av, &spec, Some((5.0, 6.0)));
+    assert!(
+        res.is_err(),
+        "expected an error for an empty PCM window, not a silent buffer"
+    );
+}
+
 #[test]
 fn waveform_has_expected_bucket_count() {
     if !ffmpeg_available() {