fix(waveform): stabilize progressive rendering and reduce streaming contention

Improve seekbar fallback behavior by using consistent bar-based rendering and smoother transitions to analyzed waveform data. Reduce hot-path analysis overhead during ranged streaming and add controls to clear cached waveform entries.

src-tauri/src/analysis_cache.rs

@@ -14,7 +14,7 @@ use symphonia::core::meta::MetadataOptions;
 use symphonia::core::probe::Hint;
 use tauri::Manager;
 
-pub const WAVEFORM_ALGO_VERSION: i64 = 1;
+pub const WAVEFORM_ALGO_VERSION: i64 = 3;
 pub const LOUDNESS_ALGO_VERSION: i64 = 1;
 
 #[derive(Debug, Clone)]
@@ -102,6 +102,18 @@ impl AnalysisCache {
         Ok(total)
     }
 
+    /// Remove all cached waveform rows across all tracks/variants.
+    pub fn delete_all_waveforms(&self) -> Result<u64, String> {
+        let conn = self
+            .conn
+            .lock()
+            .map_err(|_| "analysis_cache lock poisoned".to_string())?;
+        let n = conn
+            .execute("DELETE FROM waveform_cache", [])
+            .map_err(|e| e.to_string())?;
+        Ok(n as u64)
+    }
+
     pub fn touch_track_status(&self, key: &TrackKey, status: &str) -> Result<(), String> {
         let now = now_unix_ts();
         let conn = self.conn.lock().map_err(|_| "analysis_cache lock poisoned".to_string())?;
@@ -313,8 +325,20 @@ pub fn seed_from_bytes(app: &tauri::AppHandle, track_id: &str, bytes: &[u8]) ->
     };
     cache.touch_track_status(&key, "queued")?;
 
+    let wf_bins: Vec<u8>;
+    let loudness_opt: Option<(f64, f64, f64, f64)>;
+    match analyze_loudness_and_waveform(bytes, -16.0, 500) {
+        Some((integrated_lufs, true_peak, recommended_gain_db, target_lufs, bins)) => {
+            wf_bins = bins;
+            loudness_opt = Some((integrated_lufs, true_peak, recommended_gain_db, target_lufs));
+        }
+        None => {
+            wf_bins = derive_waveform_bins(bytes, 500);
+            loudness_opt = None;
+        }
+    }
     let waveform = WaveformEntry {
-        bins: derive_waveform_bins(bytes, 500),
+        bins: wf_bins,
         bin_count: 500,
         is_partial: false,
         known_until_sec: 0.0,
@@ -323,9 +347,7 @@ pub fn seed_from_bytes(app: &tauri::AppHandle, track_id: &str, bytes: &[u8]) ->
     };
     cache.upsert_waveform(&key, &waveform)?;
 
-    if let Some((integrated_lufs, true_peak, recommended_gain_db, target_lufs)) =
-        analyze_loudness_from_audio_bytes(bytes, -16.0)
-    {
+    if let Some((integrated_lufs, true_peak, recommended_gain_db, target_lufs)) = loudness_opt {
         let loudness = LoudnessEntry {
             integrated_lufs,
             true_peak,
@@ -372,11 +394,48 @@ fn derive_waveform_bins(bytes: &[u8], bin_count: usize) -> Vec<u8> {
     out
 }
 
-fn analyze_loudness_from_audio_bytes(bytes: &[u8], target_lufs: f64) -> Option<(f64, f64, f64, f64)> {
-    if bytes.is_empty() {
+struct PcmScanResult {
+    bins: Vec<u8>,
+    loudness: Option<(f64, f64, f64, f64)>,
+}
+
+/// Decoded PCM peak envelope (mono mix) → `bin_count` bars, for seekbar display.
+/// Two decode passes: count frames, then fill bins. Returns `None` if probing/decoding fails.
+pub fn derive_waveform_bins_from_audio_bytes(bytes: &[u8], bin_count: usize) -> Option<Vec<u8>> {
+    if bytes.is_empty() || bin_count == 0 {
         return None;
     }
+    let (decoded_frames, timeline_hint) = count_mono_frames_from_audio_bytes(bytes)?;
+    if decoded_frames == 0 {
+        return None;
+    }
+    let scanned = decode_scan_pcm(bytes, bin_count, decoded_frames, timeline_hint, None)?;
+    Some(scanned.bins)
+}
 
+/// Loudness (EBU R128) plus PCM waveform bins in one decode pass after a frame count.
+fn analyze_loudness_and_waveform(
+    bytes: &[u8],
+    target_lufs: f64,
+    bin_count: usize,
+) -> Option<(f64, f64, f64, f64, Vec<u8>)> {
+    if bytes.is_empty() || bin_count == 0 {
+        return None;
+    }
+    let (decoded_frames, timeline_hint) = count_mono_frames_from_audio_bytes(bytes)?;
+    if decoded_frames == 0 {
+        return None;
+    }
+    let scanned = decode_scan_pcm(bytes, bin_count, decoded_frames, timeline_hint, Some(target_lufs))?;
+    let (i, t, r, tgt) = scanned.loudness?;
+    Some((i, t, r, tgt, scanned.bins))
+}
+
+/// Returns `(decoded_mono_frames, container_timeline_frames)` where the second is
+/// `codec_params.n_frames` when the container reports total track length — used
+/// as a **fixed** waveform time axis so partial decodes do not remap every bin
+/// when the buffer grows.
+fn count_mono_frames_from_audio_bytes(bytes: &[u8]) -> Option<(u64, Option<u64>)> {
     let source = Box::new(Cursor::new(bytes.to_vec()));
     let mss = MediaSourceStream::new(source, Default::default());
     let hint = Hint::new();
@@ -388,33 +447,128 @@ fn analyze_loudness_from_audio_bytes(bytes: &[u8], target_lufs: f64) -> Option<(
         .default_track()
         .filter(|t| t.codec_params.codec != CODEC_TYPE_NULL)
         .or_else(|| {
-            format
-                .tracks()
-                .iter()
-                .find(|t| {
-                    t.codec_params.codec != CODEC_TYPE_NULL
-                        && t.codec_params.sample_rate.is_some()
-                        && t.codec_params.channels.is_some()
-                })
+            format.tracks().iter().find(|t| {
+                t.codec_params.codec != CODEC_TYPE_NULL
+                    && t.codec_params.sample_rate.is_some()
+                    && t.codec_params.channels.is_some()
+            })
+        })
+        .or_else(|| format.tracks().iter().find(|t| t.codec_params.codec != CODEC_TYPE_NULL))?;
+    let track_id = track.id;
+    let timeline_hint = track.codec_params.n_frames.filter(|&n| n > 0);
+    let codec_params = track.codec_params.clone();
+    let mut decoder = symphonia::default::get_codecs()
+        .make(&codec_params, &DecoderOptions::default())
+        .ok()?;
+
+    let mut total: u64 = 0;
+    let mut loop_i: u32 = 0;
+    loop {
+        let packet = match format.next_packet() {
+            Ok(packet) => packet,
+            Err(_) => break,
+        };
+        if packet.track_id() != track_id {
+            continue;
+        }
+        let decoded = match decoder.decode(&packet) {
+            Ok(buf) => buf,
+            Err(SymphoniaError::DecodeError(_)) => continue,
+            Err(SymphoniaError::ResetRequired) => break,
+            Err(_) => break,
+        };
+        let spec = *decoded.spec();
+        let n_ch = spec.channels.count();
+        if n_ch == 0 {
+            continue;
+        }
+        let mut samples = SampleBuffer::<f32>::new(decoded.capacity() as u64, spec);
+        samples.copy_interleaved_ref(decoded);
+        let n = samples.samples().len();
+        if n < n_ch || n % n_ch != 0 {
+            continue;
+        }
+        total += (n / n_ch) as u64;
+        loop_i = loop_i.wrapping_add(1);
+        if loop_i % 128 == 0 {
+            std::thread::yield_now();
+        }
+    }
+    if total == 0 {
+        None
+    } else {
+        Some((total, timeline_hint))
+    }
+}
+
+fn normalize_peak_bins(bin_max: &[f32]) -> Vec<u8> {
+    let bin_count = bin_max.len();
+    if bin_count == 0 {
+        return Vec::new();
+    }
+    let mut sorted: Vec<f32> = bin_max.to_vec();
+    sorted.sort_by(|a, b| a.partial_cmp(b).unwrap_or(std::cmp::Ordering::Equal));
+    let p5 = sorted[(sorted.len() * 5 / 100).min(sorted.len().saturating_sub(1))];
+    let p99 = sorted[(sorted.len() * 99 / 100).min(sorted.len().saturating_sub(1))];
+    let range = (p99 - p5).max(1e-8);
+    let mut out = vec![0u8; bin_count];
+    for i in 0..bin_count {
+        let t = ((bin_max[i] - p5) / range).clamp(0.0, 1.0);
+        let shaped = t.powf(0.52);
+        out[i] = (8.0 + shaped * 247.0).min(255.0) as u8;
+    }
+    out
+}
+
+fn decode_scan_pcm(
+    bytes: &[u8],
+    bin_count: usize,
+    decoded_frames: u64,
+    timeline_hint: Option<u64>,
+    loudness_target_lufs: Option<f64>,
+) -> Option<PcmScanResult> {
+    let source = Box::new(Cursor::new(bytes.to_vec()));
+    let mss = MediaSourceStream::new(source, Default::default());
+    let hint = Hint::new();
+    let probed = symphonia::default::get_probe()
+        .format(&hint, mss, &FormatOptions::default(), &MetadataOptions::default())
+        .ok()?;
+    let mut format = probed.format;
+    let track = format
+        .default_track()
+        .filter(|t| t.codec_params.codec != CODEC_TYPE_NULL)
+        .or_else(|| {
+            format.tracks().iter().find(|t| {
+                t.codec_params.codec != CODEC_TYPE_NULL
+                    && t.codec_params.sample_rate.is_some()
+                    && t.codec_params.channels.is_some()
+            })
         })
         .or_else(|| format.tracks().iter().find(|t| t.codec_params.codec != CODEC_TYPE_NULL))?;
     let track_id = track.id;
     let codec_params = track.codec_params.clone();
-
-    let mut decoder = match symphonia::default::get_codecs()
-        .make(&codec_params, &DecoderOptions::default())
-    {
+    let mut decoder = match symphonia::default::get_codecs().make(&codec_params, &DecoderOptions::default()) {
         Ok(v) => v,
         Err(e) => {
             crate::app_deprintln!("[analysis] decoder make failed: {}", e);
             return None;
         }
     };
+
+    let mut bin_max = vec![0.0f32; bin_count];
     let mut ebu: Option<EbuR128> = None;
     let mut ebu_channels: u32 = 0;
     let mut sample_peak_abs = 0.0_f64;
     let mut fed_any_frames = false;
+    let mut sample_idx: u64 = 0;
     let mut loop_i: u32 = 0;
+    // Fixed timeline from metadata when available; otherwise fall back to decoded
+    // length (full-buffer analysis only — partial byte windows still shift, but
+    // then we usually lack n_frames anyway).
+    let bin_grid_frames = timeline_hint
+        .map(|n| n.max(decoded_frames))
+        .unwrap_or(decoded_frames)
+        .max(1);
 
     loop {
         let packet = match format.next_packet() {
@@ -424,7 +578,6 @@ fn analyze_loudness_from_audio_bytes(bytes: &[u8], target_lufs: f64) -> Option<(
         if packet.track_id() != track_id {
             continue;
         }
-
         let decoded = match decoder.decode(&packet) {
             Ok(buf) => buf,
             Err(SymphoniaError::DecodeError(_)) => continue,
@@ -433,7 +586,12 @@ fn analyze_loudness_from_audio_bytes(bytes: &[u8], target_lufs: f64) -> Option<(
         };
 
         let spec = *decoded.spec();
-        if ebu.is_none() {
+        let n_ch = spec.channels.count();
+        if n_ch == 0 {
+            continue;
+        }
+
+        if loudness_target_lufs.is_some() && ebu.is_none() {
             let ch = spec.channels.count() as u32;
             let sr = spec.rate;
             match EbuR128::new(ch, sr, Ebur128Mode::I | Ebur128Mode::TRUE_PEAK) {
@@ -452,70 +610,101 @@ fn analyze_loudness_from_audio_bytes(bytes: &[u8], target_lufs: f64) -> Option<(
                 }
             }
         }
+
         let mut samples = SampleBuffer::<f32>::new(decoded.capacity() as u64, spec);
         samples.copy_interleaved_ref(decoded);
-        for &s in samples.samples() {
-            let v = (s as f64).abs();
-            if v.is_finite() && v > sample_peak_abs {
-                sample_peak_abs = v;
-            }
-        }
-        let Some(ref mut ebu) = ebu else {
-            crate::app_deprintln!("[analysis] loudness failed: ebu not initialized");
-            return None;
-        };
-        match ebu.add_frames_f32(samples.samples()) {
-            Ok(_) => fed_any_frames = true,
-            Err(e) => {
-                crate::app_deprintln!("[analysis] loudness add_frames failed: {}", e);
-                return None;
+        let slice = samples.samples();
+        if slice.len() < n_ch || slice.len() % n_ch != 0 {
+            continue;
+        }
+        let frames = slice.len() / n_ch;
+
+        for f in 0..frames {
+            let base = f * n_ch;
+            let mut acc = 0.0f32;
+            for c in 0..n_ch {
+                acc += slice[base + c];
+            }
+            let mono = acc / (n_ch as f32);
+            let mag = mono.abs();
+            if mag.is_finite() {
+                let bin = ((sample_idx * bin_count as u64) / bin_grid_frames) as usize;
+                let bin = bin.min(bin_count.saturating_sub(1));
+                bin_max[bin] = bin_max[bin].max(mag);
+            }
+            for c in 0..n_ch {
+                let v = (slice[base + c] as f64).abs();
+                if v.is_finite() && v > sample_peak_abs {
+                    sample_peak_abs = v;
+                }
+            }
+            sample_idx += 1;
+        }
+
+        if loudness_target_lufs.is_some() {
+            if let Some(e) = ebu.as_mut() {
+                match e.add_frames_f32(samples.samples()) {
+                    Ok(_) => fed_any_frames = true,
+                    Err(err) => {
+                        crate::app_deprintln!("[analysis] loudness add_frames failed: {}", err);
+                        return None;
+                    }
+                }
             }
         }
+
         loop_i = loop_i.wrapping_add(1);
         if loop_i % 128 == 0 {
             std::thread::yield_now();
         }
     }
 
-    if !fed_any_frames {
-        crate::app_deprintln!("[analysis] loudness failed: no decoded frames");
-        return None;
-    }
-    let Some(ebu) = ebu else {
-        crate::app_deprintln!("[analysis] loudness failed: no decoder output");
-        return None;
-    };
-    let integrated_lufs = match ebu.loudness_global() {
-        Ok(v) => v,
-        Err(e) => {
-            crate::app_deprintln!("[analysis] loudness_global failed: {}", e);
+    let bins = normalize_peak_bins(&bin_max);
+
+    let loudness = if let Some(target_lufs) = loudness_target_lufs {
+        if !fed_any_frames {
+            crate::app_deprintln!("[analysis] loudness failed: no decoded frames");
             return None;
         }
-    };
-    if !integrated_lufs.is_finite() {
-        crate::app_deprintln!("[analysis] loudness failed: integrated_lufs not finite");
-        return None;
-    }
-    let mut true_peak = 0.0_f64;
-    let mut true_peak_ok = true;
-    for ch in 0..ebu_channels {
-        match ebu.true_peak(ch) {
-            Ok(v) if v.is_finite() && v > true_peak => true_peak = v,
-            Ok(_) => {}
+        let Some(ebu) = ebu else {
+            crate::app_deprintln!("[analysis] loudness failed: ebu not initialized");
+            return None;
+        };
+        let integrated_lufs = match ebu.loudness_global() {
+            Ok(v) => v,
             Err(e) => {
-                true_peak_ok = false;
-                crate::app_deprintln!("[analysis] true_peak unavailable: {}", e);
-                break;
+                crate::app_deprintln!("[analysis] loudness_global failed: {}", e);
+                return None;
+            }
+        };
+        if !integrated_lufs.is_finite() {
+            crate::app_deprintln!("[analysis] loudness failed: integrated_lufs not finite");
+            return None;
+        }
+        let mut true_peak = 0.0_f64;
+        let mut true_peak_ok = true;
+        for ch in 0..ebu_channels {
+            match ebu.true_peak(ch) {
+                Ok(v) if v.is_finite() && v > true_peak => true_peak = v,
+                Ok(_) => {}
+                Err(e) => {
+                    true_peak_ok = false;
+                    crate::app_deprintln!("[analysis] true_peak unavailable: {}", e);
+                    break;
+                }
             }
         }
-    }
-    if !true_peak_ok {
-        // Fallback to sample peak if true-peak is not available for this stream/codec.
-        true_peak = sample_peak_abs;
-    }
+        if !true_peak_ok {
+            true_peak = sample_peak_abs;
+        }
+        let recommended_gain_db =
+            recommended_gain_for_target(integrated_lufs, true_peak, target_lufs);
+        Some((integrated_lufs, true_peak, recommended_gain_db, target_lufs))
+    } else {
+        None
+    };
 
-    let recommended_gain_db = recommended_gain_for_target(integrated_lufs, true_peak, target_lufs);
-    Some((integrated_lufs, true_peak, recommended_gain_db, target_lufs))
+    Some(PcmScanResult { bins, loudness })
 }
 
 fn analysis_db_path(app: &tauri::AppHandle) -> Result<PathBuf, String> {

src-tauri/src/audio.rs

@@ -1215,6 +1215,7 @@ async fn ranged_download_task(
     let dl_started = Instant::now();
     let mut next_progress_mb: usize = 1;
     let mut last_partial_emit = Instant::now();
+    let mut last_partial_emit_downloaded: usize = 0;
     let mut last_partial_loudness_emit = Instant::now() - Duration::from_secs(5);
 
     'outer: loop {
@@ -1292,10 +1293,14 @@ async fn ranged_download_task(
             downloaded_to.store(downloaded, Ordering::SeqCst);
             if downloaded >= 4096
                 && total_size > 0
+                && downloaded.saturating_sub(last_partial_emit_downloaded) >= PARTIAL_WAVEFORM_EMIT_MIN_BYTES_DELTA
                 && last_partial_emit.elapsed() >= partial_waveform_emit_min_interval(downloaded)
             {
-                let bins =
-                    derive_partial_waveform_bins_short_locks(&buf, downloaded, 500);
+                // Keep streaming path lightweight: avoid expensive PCM decode
+                // in the hot loop (it can steal CPU and cause audible underruns
+                // while playback is starting). We emit a fast sampled waveform
+                // here and let full analysis/backfill produce final bins later.
+                let bins = derive_partial_waveform_bins_short_locks(&buf, downloaded, 500);
                 if last_partial_loudness_emit.elapsed() >= Duration::from_millis(PARTIAL_LOUDNESS_EMIT_INTERVAL_MS) {
                     let target_lufs = f32::from_bits(normalization_target_lufs.load(Ordering::Relaxed));
                     if let Some(provisional_db) = provisional_loudness_gain_from_progress(downloaded, total_size, target_lufs) {
@@ -1334,6 +1339,7 @@ async fn ranged_download_task(
                     },
                 );
                 last_partial_emit = Instant::now();
+                last_partial_emit_downloaded = downloaded;
             }
             let mb = downloaded / (1024 * 1024);
             if mb >= next_progress_mb {
@@ -1386,11 +1392,11 @@ async fn ranged_download_task(
 fn partial_waveform_emit_min_interval(downloaded: usize) -> Duration {
     const MB: usize = 1024 * 1024;
     if downloaded <= 3 * MB {
-        Duration::from_millis(280)
+        Duration::from_millis(260)
     } else if downloaded <= 10 * MB {
-        Duration::from_millis(650)
+        Duration::from_millis(620)
     } else {
-        Duration::from_millis(1100)
+        Duration::from_millis(980)
     }
 }
 
@@ -2785,7 +2791,8 @@ async fn fetch_data(
 /// 10^(-1/20) ≈ 0.891 — inaudible volume difference, eliminates clipping.
 const MASTER_HEADROOM: f32 = 0.891_254;
 const PARTIAL_LOUDNESS_MIN_BYTES: usize = 256 * 1024;
-const PARTIAL_LOUDNESS_EMIT_INTERVAL_MS: u64 = 350;
+const PARTIAL_LOUDNESS_EMIT_INTERVAL_MS: u64 = 900;
+const PARTIAL_WAVEFORM_EMIT_MIN_BYTES_DELTA: usize = 192 * 1024;
 /// Until integrated LUFS is known, stay clearly below "full" level so a follow-up
 /// `audio_update_replay_gain(null)` cannot briefly blast louder than this anchor.
 const LOUDNESS_STARTUP_ATTENUATION_DB: f32 = -6.0;
@@ -3688,6 +3695,22 @@ fn spawn_progress_task(
     gapless_switch_at: Arc<AtomicU64>,
     current_playback_url: Arc<Mutex<Option<String>>>,
 ) {
+    fn estimated_output_latency_secs(sample_rate_hz: f64) -> f64 {
+        #[cfg(target_os = "linux")]
+        {
+            // Keep progress aligned with audible output (ALSA/PipeWire/Pulse
+            // queue). We mirror the quantum policy used for stream open/reopen.
+            let rate = sample_rate_hz.max(1.0);
+            let frames = if rate > 48_000.0 { 8192.0 } else { 4096.0 };
+            // Add a small scheduler/mixer cushion so UI doesn't run ahead.
+            return (frames / rate) + 0.012;
+        }
+        #[cfg(not(target_os = "linux"))]
+        {
+            0.0
+        }
+    }
+
     tokio::spawn(async move {
         let mut near_end_ticks: u32 = 0;
         // Local done-flag reference; swapped on gapless transition.
@@ -3775,21 +3798,25 @@ fn spawn_progress_task(
             let samples = samples_played.load(Ordering::Relaxed) as f64;
             let divisor = (rate * ch).max(1.0);
 
-            let dur = {
+            // Read playback snapshot under a single lock to minimize contention
+            // with seek/play/pause commands that also touch `current`.
+            let (dur, paused_at) = {
                 let cur = current_arc.lock().unwrap();
-                cur.duration_secs
-            };
-            let is_paused = {
-                let cur = current_arc.lock().unwrap();
-                cur.paused_at.is_some()
+                (cur.duration_secs, cur.paused_at)
             };
+            let is_paused = paused_at.is_some();
 
-            let pos = if is_paused {
-                let cur = current_arc.lock().unwrap();
-                cur.paused_at.unwrap_or(0.0)
+            let pos_raw = if let Some(p) = paused_at {
+                p
             } else {
                 (samples / divisor).min(dur.max(0.001))
             };
+            let progress_latency = if is_paused {
+                0.0
+            } else {
+                estimated_output_latency_secs(rate)
+            };
+            let pos = (pos_raw - progress_latency).max(0.0);
 
             app.emit("audio:progress", ProgressPayload { current_time: pos, duration: dur }).ok();
 
@@ -3801,7 +3828,7 @@ fn spawn_progress_task(
             let cf_secs = f32::from_bits(crossfade_secs_arc.load(Ordering::Relaxed)).clamp(0.5, 12.0) as f64;
             let end_threshold = if cf_enabled { cf_secs.max(1.0) } else { 1.0 };
 
-            if dur > end_threshold && pos >= dur - end_threshold {
+            if dur > end_threshold && pos_raw >= dur - end_threshold {
                 near_end_ticks += 1;
                 // At 100 ms ticks, 10 ticks ≈ 1 s — equivalent to the old 2×500ms.
                 if near_end_ticks >= 10 {

src-tauri/src/lib.rs

@@ -1258,6 +1258,13 @@ fn analysis_delete_loudness_for_track(
     cache.delete_loudness_for_track_id(&track_id)
 }
 
+#[tauri::command]
+fn analysis_delete_all_waveforms(
+    cache: tauri::State<'_, analysis_cache::AnalysisCache>,
+) -> Result<u64, String> {
+    cache.delete_all_waveforms()
+}
+
 #[tauri::command]
 fn analysis_enqueue_seed_from_url(
     track_id: String,
@@ -4108,6 +4115,7 @@ pub fn run() {
             analysis_get_waveform_for_track,
             analysis_get_loudness_for_track,
             analysis_delete_loudness_for_track,
+            analysis_delete_all_waveforms,
             analysis_enqueue_seed_from_url,
             download_track_offline,
             delete_offline_track,

src/components/WaveformSeek.tsx

@@ -8,6 +8,8 @@ function fmt(s: number): string {
 
 const BAR_COUNT = 500;
 const SEG_COUNT = 60;
+const FLAT_WAVE_NORM = 0.06;
+const WAVE_MORPH_MS = 1000;
 
 // ── animation state ───────────────────────────────────────────────────────────
 
@@ -96,6 +98,22 @@ export function makeHeights(trackId: string): Float32Array {
 
 // ── draw functions ────────────────────────────────────────────────────────────
 
+function makeFlatWaveHeights(): Float32Array {
+  const h = new Float32Array(BAR_COUNT);
+  h.fill(FLAT_WAVE_NORM);
+  return h;
+}
+
+function easeOutCubic(t: number): number {
+  const x = Math.max(0, Math.min(1, t));
+  return 1 - Math.pow(1 - x, 3);
+}
+
+function waveformBarThickness(logicalH: number, norm: number): number {
+  const safeNorm = Math.max(FLAT_WAVE_NORM, norm);
+  return Math.max(1, safeNorm * logicalH);
+}
+
 function drawWaveform(
   canvas: HTMLCanvasElement,
   heights: Float32Array | null,
@@ -108,9 +126,38 @@ function drawWaveform(
   const { played, buffered: buffCol, unplayed } = getColors();
 
   if (!heights) {
-    ctx.globalAlpha = 0.3;
+    // No waveform data yet: flat rail like `drawLineDot`, but do not return early
+    // before played/buffered — otherwise there is no visible playhead.
+    const cy = h / 2;
+    const lh = 2;
+    const dotR = 5;
+    ctx.globalAlpha = 0.35;
     ctx.fillStyle = unplayed;
-    ctx.fillRect(0, (h - 2) / 2, w, 2);
+    ctx.fillRect(0, cy - lh / 2, w, lh);
+    if (buffered > 0) {
+      ctx.globalAlpha = 0.55;
+      ctx.fillStyle = buffCol;
+      ctx.fillRect(0, cy - lh / 2, Math.min(1, buffered) * w, lh);
+    }
+    if (progress > 0) {
+      ctx.globalAlpha = 1;
+      ctx.fillStyle = played;
+      ctx.shadowColor = played;
+      ctx.shadowBlur = 5;
+      ctx.fillRect(0, cy - lh / 2, Math.min(1, progress) * w, lh);
+      ctx.shadowBlur = 0;
+    }
+    ctx.globalAlpha = 1;
+    if (w > 0) {
+      const dx = Math.max(dotR, Math.min(w - dotR, Math.min(1, progress) * w));
+      ctx.shadowColor = played;
+      ctx.shadowBlur = 7;
+      ctx.beginPath();
+      ctx.arc(dx, cy, dotR, 0, Math.PI * 2);
+      ctx.fillStyle = played;
+      ctx.fill();
+      ctx.shadowBlur = 0;
+    }
     ctx.globalAlpha = 1;
     return;
   }
@@ -122,7 +169,7 @@ function drawWaveform(
   ctx.fillStyle = unplayed;
   for (let i = 0; i < BAR_COUNT; i++) {
     if (i / BAR_COUNT < buffered) continue;
-    const bh = Math.max(1, heights[i] * h);
+    const bh = waveformBarThickness(h, heights[i]);
     const x = x1Of(i);
     ctx.fillRect(x, (h - bh) / 2, x2Of(i) - x, bh);
   }
@@ -132,7 +179,7 @@ function drawWaveform(
   for (let i = 0; i < BAR_COUNT; i++) {
     const frac = i / BAR_COUNT;
     if (frac < progress || frac >= buffered) continue;
-    const bh = Math.max(1, heights[i] * h);
+    const bh = waveformBarThickness(h, heights[i]);
     const x = x1Of(i);
     ctx.fillRect(x, (h - bh) / 2, x2Of(i) - x, bh);
   }
@@ -140,29 +187,14 @@ function drawWaveform(
   if (progress > 0) {
     ctx.globalAlpha = 1;
     ctx.fillStyle = played;
-    ctx.shadowColor = played;
-    ctx.shadowBlur = 5;
     for (let i = 0; i < BAR_COUNT; i++) {
       if (i / BAR_COUNT >= progress) break;
-      const bh = Math.max(1, heights[i] * h);
+      const bh = waveformBarThickness(h, heights[i]);
       const x = x1Of(i);
       ctx.fillRect(x, (h - bh) / 2, x2Of(i) - x, bh);
     }
-    ctx.shadowBlur = 0;
   }
   ctx.globalAlpha = 1;
-
-  // Fade both edges to transparent using destination-in gradient mask
-  const fadeW = Math.min(22, w * 0.07);
-  const mask = ctx.createLinearGradient(0, 0, w, 0);
-  mask.addColorStop(0, 'transparent');
-  mask.addColorStop(fadeW / w, 'black');
-  mask.addColorStop(1 - fadeW / w, 'black');
-  mask.addColorStop(1, 'transparent');
-  ctx.globalCompositeOperation = 'destination-in';
-  ctx.fillStyle = mask;
-  ctx.fillRect(0, 0, w, h);
-  ctx.globalCompositeOperation = 'source-over';
 }
 
 function drawLineDot(canvas: HTMLCanvasElement, progress: number, buffered: number) {
@@ -824,7 +856,6 @@ export default function WaveformSeek({ trackId }: Props) {
   const SEEK_COMMIT_PROGRESS_EPS = 0.02;
   const canvasRef    = useRef<HTMLCanvasElement>(null);
   const heightsRef   = useRef<Float32Array | null>(null);
-  const lastHeightsTrackIdRef = useRef<string | undefined>(undefined);
   const progressRef  = useRef(usePlayerStore.getState().progress);
   const bufferedRef  = useRef(usePlayerStore.getState().buffered);
   const isDragging   = useRef(false);
@@ -848,43 +879,73 @@ export default function WaveformSeek({ trackId }: Props) {
   useEffect(() => {
     if (!trackId) {
       heightsRef.current = null;
-      lastHeightsTrackIdRef.current = undefined;
       return;
     }
     if (waveformBins && waveformBins.length > 0) {
       const src = waveformBins;
       const h = new Float32Array(BAR_COUNT);
-      const effectiveDur = waveformDurationSec > 0 ? waveformDurationSec : duration;
-      const knownFrac = waveformIsPartial && effectiveDur > 0
-        ? Math.max(0, Math.min(1, waveformKnownUntilSec / effectiveDur))
-        : 1;
-      const knownBars = Math.max(0, Math.min(BAR_COUNT, Math.floor(knownFrac * BAR_COUNT)));
       for (let i = 0; i < BAR_COUNT; i++) {
-        if (i >= knownBars) {
-          h[i] = 0.08; // unknown tail baseline while partial waveform is still loading
-          continue;
-        }
         const idx = Math.min(src.length - 1, Math.floor((i / BAR_COUNT) * src.length));
         const v = src[idx];
         h[i] = Math.max(0.08, Math.min(1, (Number(v) / 255)));
       }
-      // Partial -> full handoff: blend with previous heights for a smoother
-      // visual transition and avoid a hard "jump" in the waveform shape.
-      if (lastHeightsTrackIdRef.current === trackId && heightsRef.current && heightsRef.current.length === BAR_COUNT) {
-        const prev = heightsRef.current;
-        const mixed = new Float32Array(BAR_COUNT);
-        for (let i = 0; i < BAR_COUNT; i++) {
-          mixed[i] = prev[i] * 0.45 + h[i] * 0.55;
-        }
-        heightsRef.current = mixed;
-      } else {
+      const prev = heightsRef.current;
+      if (!prev || prev.length !== BAR_COUNT) {
         heightsRef.current = h;
+        return;
       }
-      lastHeightsTrackIdRef.current = trackId;
-      return;
+      const from = new Float32Array(prev);
+      const to = h;
+      const startedAt = performance.now();
+      let raf = 0;
+      const step = (now: number) => {
+        const p = easeOutCubic((now - startedAt) / WAVE_MORPH_MS);
+        const next = new Float32Array(BAR_COUNT);
+        for (let i = 0; i < BAR_COUNT; i++) {
+          next[i] = from[i] + (to[i] - from[i]) * p;
+        }
+        heightsRef.current = next;
+        if (!ANIMATED_STYLES.has(styleRef.current)) {
+          const canvas = canvasRef.current;
+          if (canvas) drawSeekbar(canvas, styleRef.current, next, progressRef.current, bufferedRef.current, animStateRef.current);
+        }
+        if (p < 1) raf = requestAnimationFrame(step);
+      };
+      raf = requestAnimationFrame(step);
+      return () => cancelAnimationFrame(raf);
     }
-    heightsRef.current = makeHeights(trackId);
-    lastHeightsTrackIdRef.current = trackId;
+    if (heightsRef.current?.length === BAR_COUNT) {
+      const current = heightsRef.current;
+      let isAlreadyFlat = true;
+      for (let i = 0; i < BAR_COUNT; i++) {
+        if (Math.abs(current[i] - FLAT_WAVE_NORM) > 0.0001) {
+          isAlreadyFlat = false;
+          break;
+        }
+      }
+      if (isAlreadyFlat) return;
+      const from = new Float32Array(current);
+      const to = makeFlatWaveHeights();
+      const startedAt = performance.now();
+      let raf = 0;
+      const step = (now: number) => {
+        const p = easeOutCubic((now - startedAt) / WAVE_MORPH_MS);
+        const next = new Float32Array(BAR_COUNT);
+        for (let i = 0; i < BAR_COUNT; i++) {
+          next[i] = from[i] + (to[i] - from[i]) * p;
+        }
+        heightsRef.current = next;
+        if (!ANIMATED_STYLES.has(styleRef.current)) {
+          const canvas = canvasRef.current;
+          if (canvas) drawSeekbar(canvas, styleRef.current, next, progressRef.current, bufferedRef.current, animStateRef.current);
+        }
+        if (p < 1) raf = requestAnimationFrame(step);
+      };
+      raf = requestAnimationFrame(step);
+      return () => cancelAnimationFrame(raf);
+    }
+    // No analysis bins yet: render 500 flat bars immediately.
+    heightsRef.current = makeFlatWaveHeights();
   }, [trackId, waveformBins, waveformIsPartial, waveformKnownUntilSec, waveformDurationSec, duration]);
 
   // Imperative subscription — no React re-renders from progress changes.
@@ -913,12 +974,20 @@ export default function WaveformSeek({ trackId }: Props) {
     });
   }, []);
 
-  // Initial draw for static styles when style or track changes.
+  // Initial draw for static styles when style, track, or waveform payload changes.
   useEffect(() => {
     if (ANIMATED_STYLES.has(seekbarStyle)) return;
     const canvas = canvasRef.current;
     if (canvas) drawSeekbar(canvas, seekbarStyle, heightsRef.current, progressRef.current, bufferedRef.current);
-  }, [seekbarStyle, trackId]);
+  }, [
+    seekbarStyle,
+    trackId,
+    waveformBins,
+    waveformIsPartial,
+    waveformKnownUntilSec,
+    waveformDurationSec,
+    duration,
+  ]);
 
   // rAF loop — animated styles only.
   useEffect(() => {

src/locales/en.ts

@@ -656,9 +656,12 @@ export const enTranslation = {
     hotCacheTrackCount: 'Tracks in cache:',
     cacheMaxLabel: 'Max. size',
     cacheClearBtn: 'Clear Cache',
+    waveformCacheClearBtn: 'Clear waveform cache',
     cacheClearWarning: 'This will also remove all offline albums from the library.',
     cacheClearConfirm: 'Clear Everything',
     cacheClearCancel: 'Cancel',
+    waveformCacheCleared: 'Waveform cache cleared ({{count}} rows).',
+    waveformCacheClearFailed: 'Failed to clear waveform cache.',
     offlineDirTitle: 'Offline Library (In-App)',
     offlineDirDesc: 'Storage location for tracks you make available offline within Psysonic.',
     offlineDirDefault: 'Default (App Data)',

src/locales/ru.ts

@@ -677,9 +677,12 @@ export const ruTranslation = {
     hotCacheTrackCount: 'Треков в кэше:',
     cacheMaxLabel: 'Лимит',
     cacheClearBtn: 'Очистить кэш',
+    waveformCacheClearBtn: 'Очистить кэш waveform',
     cacheClearWarning: 'Будут удалены и все офлайн-альбомы.',
     cacheClearConfirm: 'Очистить всё',
     cacheClearCancel: 'Отмена',
+    waveformCacheCleared: 'Кэш waveform очищен ({{count}} строк).',
+    waveformCacheClearFailed: 'Не удалось очистить кэш waveform.',
     offlineDirTitle: 'Офлайн-библиотека (в приложении)',
     offlineDirDesc: 'Папка для треков, сохранённых для офлайн-прослушивания.',
     offlineDirDefault: 'По умолчанию (данные приложения)',

src/pages/Settings.tsx

@@ -17,6 +17,7 @@ import { open as openUrl } from '@tauri-apps/plugin-shell';
 import { getImageCacheSize, clearImageCache } from '../utils/imageCache';
 import { useOfflineStore } from '../store/offlineStore';
 import { useHotCacheStore } from '../store/hotCacheStore';
+import { usePlayerStore } from '../store/playerStore';
 import { lastfmGetToken, lastfmAuthUrl, lastfmGetSession, lastfmGetUserInfo, LastfmUserInfo } from '../api/lastfm';
 import LastfmIcon from '../components/LastfmIcon';
 import CustomSelect from '../components/CustomSelect';
@@ -1788,6 +1789,29 @@ export default function Settings() {
     setClearing(false);
   }, [clearAllOffline, serverId]);
 
+  const handleClearWaveformCache = useCallback(async () => {
+    setClearing(true);
+    try {
+      const deleted = await invoke<number>('analysis_delete_all_waveforms');
+      usePlayerStore.setState({
+        waveformBins: null,
+        waveformIsPartial: false,
+        waveformKnownUntilSec: 0,
+        waveformDurationSec: 0,
+      });
+      showToast(
+        t('settings.waveformCacheCleared', { count: deleted }),
+        3500,
+        'success',
+      );
+    } catch (e) {
+      console.error(e);
+      showToast(t('settings.waveformCacheClearFailed'), 4500, 'error');
+    } finally {
+      setClearing(false);
+    }
+  }, [t]);
+
   const startLastfmConnect = useCallback(async () => {
     setLfmError(null);
     let token: string;
@@ -3032,6 +3056,16 @@ export default function Settings() {
                   <Trash2 size={14} /> {t('settings.cacheClearBtn')}
                 </button>
               )}
+              <div style={{ marginTop: 8 }}>
+                <button
+                  className="btn btn-ghost"
+                  style={{ fontSize: 13 }}
+                  onClick={handleClearWaveformCache}
+                  disabled={clearing}
+                >
+                  <Trash2 size={14} /> {t('settings.waveformCacheClearBtn')}
+                </button>
+              </div>
             </div>
           </SettingsSubSection>
 

src/store/playerStore.ts

@@ -824,19 +824,11 @@ function handleAudioProgress(current_time: number, duration: number) {
   const dur = duration > 0 ? duration : track.duration;
   if (dur <= 0) return;
   const progress = displayTime / dur;
-  const stateNow = usePlayerStore.getState();
-  if (stateNow.waveformIsPartial) {
-    usePlayerStore.setState({
-      currentTime: displayTime,
-      progress,
-      buffered: 0,
-      // Keep known span aligned with playback position during partial stage:
-      // if playback moved forward, this part is definitely known already.
-      waveformKnownUntilSec: Math.max(stateNow.waveformKnownUntilSec || 0, displayTime),
-    });
-  } else {
-    usePlayerStore.setState({ currentTime: displayTime, progress, buffered: 0 });
-  }
+  // Do not couple `waveformKnownUntilSec` to playhead: for partial streams it
+  // must track **download/analysis progress** (emitted in `analysis:waveform-partial`).
+  // Using `displayTime` here broke the seekbar after seeks — bins only cover the
+  // buffered prefix of the file while `knownUntil` jumped with the seek position.
+  usePlayerStore.setState({ currentTime: displayTime, progress, buffered: 0 });
 
   // Scrobble at 50%: Last.fm + Navidrome (updates play_date / recently played)
   if (progress >= 0.5 && !store.scrobbled) {
@@ -1123,11 +1115,37 @@ export function initAudioListeners(): () => void {
         usePlayerStore.setState({ waveformIsPartial: false, waveformKnownUntilSec: 0 });
         return;
       }
-      usePlayerStore.setState({
-        waveformBins: payload.bins,
-        waveformIsPartial: true,
-        waveformKnownUntilSec: Number.isFinite(payload.knownUntilSec) ? payload.knownUntilSec : 0,
-        waveformDurationSec: Number.isFinite(payload.durationSec) ? payload.durationSec : (current.duration || 0),
+      const nextKnownUntilSec = Number.isFinite(payload.knownUntilSec) ? payload.knownUntilSec : 0;
+      const nextDurationSec = Number.isFinite(payload.durationSec) ? payload.durationSec : (current.duration || 0);
+      usePlayerStore.setState((prev) => {
+        const prevBins = prev.waveformBins;
+        const prevKnownUntilSec = Number.isFinite(prev.waveformKnownUntilSec) ? prev.waveformKnownUntilSec : 0;
+        if (!prevBins || prevBins.length === 0 || prevKnownUntilSec <= 0 || nextDurationSec <= 0) {
+          return {
+            waveformBins: payload.bins,
+            waveformIsPartial: true,
+            waveformKnownUntilSec: nextKnownUntilSec,
+            waveformDurationSec: nextDurationSec,
+          };
+        }
+        const len = Math.max(prevBins.length, payload.bins.length);
+        const merged = new Array<number>(len);
+        for (let i = 0; i < len; i++) {
+          merged[i] = i < prevBins.length ? prevBins[i] : 0;
+        }
+        const prevKnownBars = Math.max(0, Math.min(len, Math.floor((prevKnownUntilSec / nextDurationSec) * len)));
+        const nextKnownBars = Math.max(0, Math.min(len, Math.floor((nextKnownUntilSec / nextDurationSec) * len)));
+        if (nextKnownBars > prevKnownBars) {
+          for (let i = prevKnownBars; i < nextKnownBars; i++) {
+            if (i < payload.bins.length) merged[i] = payload.bins[i];
+          }
+        }
+        return {
+          waveformBins: merged,
+          waveformIsPartial: true,
+          waveformKnownUntilSec: Math.max(prevKnownUntilSec, nextKnownUntilSec),
+          waveformDurationSec: nextDurationSec,
+        };
       });
     }),
     listen<{ trackId?: string | null; gainDb: number; targetLufs: number; isPartial: boolean }>('analysis:loudness-partial', ({ payload }) => {
@@ -1151,6 +1169,9 @@ export function initAudioListeners(): () => void {
       if (!payloadTrackId) return;
       const currentId = usePlayerStore.getState().currentTrack?.id;
       if (currentId && payloadTrackId === currentId) {
+        if (!payload.isPartial) {
+          usePlayerStore.setState({ waveformIsPartial: false });
+        }
         void refreshWaveformForTrack(currentId);
         void refreshLoudnessForTrack(currentId);
         emitNormalizationDebug('backfill:applied', { trackId: currentId });