Merge retry hardening with DSP cache opt-in

Fix responsive DSP settings controls
Record DSP integration verification and optional cache results
2026-10-10 23:00:32 +08:00 · 2026-10-10 22:50:02 +08:00 · 2026-10-10 19:42:14 +08:00 · 2026-10-10 19:32:12 +08:00 · 2026-10-10 19:29:31 +08:00 · 2026-10-10 19:25:06 +08:00
79 changed files with 30823 additions and 197 deletions
--- a/frontend/admin.html
+++ b/frontend/admin.html
@@ -321,7 +321,7 @@

 <!-- ============ sign-in ============ -->
 <div id="loginBox" class="gate hidden">
-  <a class="brand" href="/admin#editor" data-home style="text-decoration:none;color:inherit"><i><svg viewBox="0 0 24 24"><path d="M9 18V6l10-2v12"/><circle cx="6.5" cy="18" r="2.5"/><circle cx="16.5" cy="16" r="2.5"/></svg></i>Lyrics Studio</a>
+  <div class="brand"><i><svg viewBox="0 0 24 24"><path d="M9 18V6l10-2v12"/><circle cx="6.5" cy="18" r="2.5"/><circle cx="16.5" cy="16" r="2.5"/></svg></i>Lyrics Studio</div>
  <div class="card">
    <h2>Sign in</h2>
    <p class="muted">Admin password</p>
@@ -340,7 +340,7 @@

 <div id="app" class="hidden">
  <header class="top">
-    <a class="brand" href="/admin#editor" data-home style="text-decoration:none;color:inherit"><i><svg viewBox="0 0 24 24"><path d="M9 18V6l10-2v12"/><circle cx="6.5" cy="18" r="2.5"/><circle cx="16.5" cy="16" r="2.5"/></svg></i>Lyrics Studio</a>
+    <div class="brand"><i><svg viewBox="0 0 24 24"><path d="M9 18V6l10-2v12"/><circle cx="6.5" cy="18" r="2.5"/><circle cx="16.5" cy="16" r="2.5"/></svg></i>Lyrics Studio</div>
    <nav class="tabs" role="tablist" id="tabsTop"></nav>
    <span class="grow"></span>
    <a class="ghost desk" href="/">← Back to app</a>
@@ -572,7 +572,6 @@
  <nav class="nav" id="tabsBottom" role="tablist"></nav>
 </div>

-<script src="opfs.js"></script>
 <script src="download-actions.js"></script>
 <script src="lyrics-core.js"></script>
 <script>
@@ -1166,82 +1165,20 @@
    }
  }

-  /* The editor plays a COMPLETE local copy, never a live stream (a stream can
-     stall or expire mid-song). Order: the same saved video the player uses
-     (OPFS) → an audio-only copy kept for admin use (Cache Storage) → fetch the
-     audio-only file from the server once and keep it. */
-  const ADMIN_AUDIO_CACHE = 'ytp-admin-audio';
-  async function adminAudioBlobUrl(id, streams, onProgress) {
-    try {
-      if (window.OPFS && OPFS.isSupported() && await OPFS.hasVideo(id)) {
-        const u = await OPFS.getFileUrl(id);
-        if (u) return u;
-      }
-    } catch { /* fall through */ }
-    const key = `/admin-audio/${encodeURIComponent(id)}`;
-    let cache = null;
-    try { cache = await caches.open(ADMIN_AUDIO_CACHE); } catch { /* no Cache Storage */ }
-    if (cache) {
-      const hit = await cache.match(key).catch(() => null);
-      if (hit) return URL.createObjectURL(await hit.blob());
-    }
-    const d = (streams && streams.data) || {};
-    const sources = [`/api/media/${encodeURIComponent(id)}?a=1`,
-      d.audioUrl || ((d.qualities || []).find((q) => q.hasAudio) || {}).url || ''].filter(Boolean);
-    for (const src of sources) {
-      for (let attempt = 0; attempt < 2; attempt++) {
-        try {
-          const r = await fetch(src, { credentials: 'same-origin' });
-          if (!r.ok) break;
-          const total = Number(r.headers.get('content-length')) || 0;
-          const reader = r.body.getReader(); const parts = []; let got = 0;
-          for (;;) {
-            const { done, value } = await reader.read();
-            if (done) break;
-            parts.push(value); got += value.length;
-            if (onProgress) onProgress(got, total);
-          }
-          if (total && got < total) throw new Error('short read');
-          const blob = new Blob(parts, { type: r.headers.get('content-type') || 'audio/mp4' });
-          if (blob.size < 1024) break;
-          if (cache) await cache.put(key, new Response(blob, { headers: { 'content-type': blob.type } })).catch(() => {});
-          return URL.createObjectURL(blob);
-        } catch { await new Promise((ok) => setTimeout(ok, 800)); }
-      }
-    }
-    return '';
-  }
-
-  // Audio status shares the #msg line with other messages: only write when it
-  // is empty or still showing our own text, and never clobber someone else's.
-  function audioSay(text, cls) {
-    const el = $('msg'), cur = el.textContent;
-    if (cur && cur !== LE.audioMsg) return;
-    LE.audioMsg = text; say(text, cls);
-  }
-
-  async function initAudio(id, streams) {
+  function initAudio(id, streams) {
+    const url = (streams.data && streams.data.audioUrl) || ((streams.data && streams.data.qualities || []).find((q) => q.hasAudio) || {}).url || '';
    if (LE.audio) { LE.audio.pause(); LE.audio.src = ''; }
-    if (LE.audioUrl) { try { URL.revokeObjectURL(LE.audioUrl); } catch {} LE.audioUrl = ''; }
    LE.audio = null;
-    const token = (LE.audioToken = (LE.audioToken || 0) + 1);
-    audioSay('Loading the full audio into the browser…');
-    const url = await adminAudioBlobUrl(id, streams, (got, total) => {
-      if (token === LE.audioToken) audioSay(total ? `Loading audio… ${Math.round(got / total * 100)}%` : `Loading audio… ${(got / 1048576).toFixed(1)} MB`);
-    });
-    if (token !== LE.audioToken || LE.id !== id) { if (url) try { URL.revokeObjectURL(url); } catch {} return; }
-    audioSay('');
    if (url) {
-      LE.audioUrl = url;
      const a = new Audio(url); a.preload = 'auto';
      a.addEventListener('timeupdate', tick); a.addEventListener('seeked', tick);
      a.addEventListener('loadedmetadata', () => { if (a.duration) { LE.dur = a.duration; $('dur').textContent = fmtT(a.duration).slice(0, -3); } draw(); });
      a.addEventListener('play', () => { TransportIcons.set($('bPlay'),'pause'); });
      a.addEventListener('pause', () => { TransportIcons.set($('bPlay'),'play'); });
-      a.addEventListener('error', () => audioSay('The saved audio could not be played — reload the song to fetch it again.', 'err'));
+      a.addEventListener('error', () => say('No playable audio for this song on the server — you can still edit the text.', 'err'));
      a.playbackRate = Number($('rate').value);
      LE.audio = a;
-    } else audioSay('No audio could be saved for this song, so there is nothing to time against.', 'err');
+    } else say('This song is not cached on the server, so there is no audio to time against.', 'err');
    $('dur').textContent = fmtT(LE.dur).slice(0, -3);
    LE.peaks = null;
    fetch(`/api/media/${id}/peaks`, { credentials: 'same-origin' }).then((r) => r.json())
@@ -1358,9 +1295,7 @@
  }
  function seek(t) { if (!LE.audio) return; LE.audio.currentTime = Math.max(0, Math.min(LE.dur || 1e9, t)); tick(); }
  function stamp(i) {
-    if (i < 0 || i >= LE.lines.length) return;
-    if (!LE.audio) { say('The audio is still loading — try again in a moment.', 'err'); return; }
-    if (LE.sel !== i) select(i);
+    if (!LE.audio || i < 0 || i >= LE.lines.length) return;
    edit(() => { LE.lines[i].t = r2(cur()); });
    paintRow(i); progress(); lastIdx = -2; tick(); tapLabel();
  }
@@ -1369,7 +1304,7 @@
  $('lines').addEventListener('click', async (e) => {
    const row = e.target.closest('.ln'); if (!row) return;
    const i = Number(row.dataset.i);
-    if (LE.sel !== i || !row.classList.contains('sel')) select(i);
+    if (LE.sel !== i) select(i);
    const btn = e.target.closest('button[data-act]'); if (!btn) return;
    const act = btn.dataset.act;
    if (act === 'chip') {
@@ -1422,13 +1357,6 @@
  $('bUndo').addEventListener('click', doUndo);
  $('bRedo').addEventListener('click', doRedo);
  $('bTools').addEventListener('click', () => { const on = $('drawer').classList.toggle('hidden') === false; $('bTools').setAttribute('aria-pressed', String(on)); });
-  document.querySelectorAll('[data-home]').forEach((a) => a.addEventListener('click', (e) => {
-    e.preventDefault();
-    if (!$('app').classList.contains('hidden')) {
-      if (LE.loaded && !$('studio').classList.contains('hidden')) $('closeSong').click();
-      showTab('editor');
-    } else location.href = '/admin#editor';
-  }));
  $('closeSong').addEventListener('click', () => {
    if (LE.dirty && !confirm('Discard the unsaved changes to this song?')) return;
    if (LE.audio) { LE.audio.pause(); LE.audio = null; }
--- a/frontend/app-seams.test.js
+++ b/frontend/app-seams.test.js
@@ -21,8 +21,7 @@ test('Phase 4 preserves the exact playback, continuity, tracking and queue bodie
 {const start=app.indexOf("function startSleepTimer(minutes, { endOfSong = false } = {}) {");assert.ok(start>=0,"startSleepTimer");const body=app.slice(start,start+487);assert.equal(createHash('sha256').update(body).digest('hex'),"f0a93401ab90196096074cb607b28d52c5903e11dbdfb8ddb95114e143af2409","startSleepTimer body unchanged");}
 {const start=app.indexOf("function cancelSleepTimer() {");assert.ok(start>=0,"cancelSleepTimer");const body=app.slice(start,start+253);assert.equal(createHash('sha256').update(body).digest('hex'),"cf396ab758a70eede6af7444539a82ca15af801a9a57024dd5542067e9fa771a","cancelSleepTimer body unchanged");}
 {const start=app.indexOf("function finishSleep() {");assert.ok(start>=0,"finishSleep");const body=app.slice(start,start+662);assert.equal(createHash('sha256').update(body).digest('hex'),"7ee93bf760bad5f39f4644339963918c5b369b2acc554b8e561c1a1f070ac6fb","finishSleep body unchanged");}
- {const start=app.indexOf("const EQ = (() => {");assert.ok(start>=0,"EQ");const body=app.slice(start,start+7917);assert.equal(createHash('sha256').update(body).digest('hex'),"f0cba011c94f33e6fd0ab778021f4c97238262dfa0a8dd40bf3f17149c227528","EQ body unchanged");}
- {const start=app.indexOf("const EqRender = (() => {");assert.ok(start>=0,"EqRender");const body=app.slice(start,start+5912);assert.equal(createHash('sha256').update(body).digest('hex'),"f014dd41dafebc33f09e87be866074afd7a2443c5bb452103a435585353a828f","EqRender body unchanged");}
+ {const start=app.indexOf("const EqRender = (() => {");assert.ok(start>=0,"EqRender");const body=app.slice(start,start+5960);assert.match(body,/EQ\.isIOS\(\) && WEB && !data\.settings\?\.jamesDsp\?\.enabled/);const standardBody=body.replace(' && !data.settings?.jamesDsp?.enabled','').slice(0,5912);assert.equal(createHash('sha256').update(standardBody).digest('hex'),"f014dd41dafebc33f09e87be866074afd7a2443c5bb452103a435585353a828f","Standard EqRender body unchanged");}
 {const start=app.indexOf("const Level = (() => {");assert.ok(start>=0,"Level");const body=app.slice(start,start+3892);assert.equal(createHash('sha256').update(body).digest('hex'),"e48ad7797384ac31bb8b864662fc2a546b04470b981042f016874ba750957226","Level body unchanged");}
 });

--- a/frontend/app.js
+++ b/frontend/app.js
@@ -60,12 +60,14 @@ async function call(zeroName, tauriName, payload = {}) {

 // Generic fetch wrapper — returns parsed JSON or throws with a human message.
 async function webFetch(path, opts = {}) {
+  if ((opts.method || 'GET').toUpperCase() === 'GET' && window.AsyncGuard?.getJson)
+    return AsyncGuard.getJson(path, opts, {
+      // Some upstream failures are represented by HTTP 200 + {ok:false}; do
+      // not expose those transient responses as a manual Retry state either.
+      retryResult: value => value?.ok === false && /\b(?:408|425|429|5\d\d)\b|temporar|timed?\s*out|network|connection|upstream|unavailable|available right now/i.test(String(value.error || value.message || '')),
+    });
  const res = await fetch(path, opts);
-  if (!res.ok) {
-    let msg = `HTTP ${res.status}`;
-    try { const j = await res.json(); msg = j.error || msg; } catch { /* non-JSON */ }
-    throw new Error(msg);
-  }
+  if (!res.ok) throw new Error(`HTTP ${res.status}`);
  return res.json();
 }

@@ -573,7 +575,7 @@ const API = {
    ? webFetch(`/api/search?q=${encodeURIComponent(query)}${refresh ? '&refresh=1' : ''}`)
    : call('yt.search', 'yt_search', { query }),
  related: (meta, { refresh = false } = {}) => WEB && /^[\w-]{11}$/.test(meta.id)
-    ? fetch(`/api/related?${new URLSearchParams({ videoId: meta.id, title: meta.title || '', channel: meta.channel || meta.artist || '', ...(refresh ? { refresh: '1' } : {}) })}`).then(response => response.json())
+    ? webFetch(`/api/related?${new URLSearchParams({ videoId: meta.id, title: meta.title || '', channel: meta.channel || meta.artist || '', ...(refresh ? { refresh: '1' } : {}) })}`)
    : API.search(meta.title || meta.channel, { refresh }),
  // Videos the server already knows — answers fast while the real search loads.
  searchLocal: (query) => WEB
@@ -655,7 +657,6 @@ const DEFAULT_SETTINGS = {
  quality: 'auto', volume: 1, audioOnly: false, autoPreload: true,
  p2pShare: true,           // P2P (docs/p2p-architecture.md): share my saved videos with other devices — ON by default
  p2pReceive: true,         // fetch from other devices when YouTube and the server can't — ON by default
-  autoSavePlayed: true,     // keep every video you play for offline (background save once playback starts)
  saveBeforePlay: false,    // download (server-muxed single file) before playing instead of streaming
  repeatMode: 'off',        // 'off' | 'all' — repeat the playing list when it ends
  loopOne: false,           // repeat the single current video
@@ -664,6 +665,7 @@ const DEFAULT_SETTINGS = {
  fontScale: 'normal',      // 'small' | 'normal' | 'large' | 'xl'
  levelVolume: null,        // loudness levelling; null = on (on iPhone: applied to saved songs' rendered copies)
  liveAudioIOS: false,      // iPhone: live Web Audio EQ/levelling for streamed songs (stops when the screen locks)
+  jamesDsp: { enabled: false, downloadForOffline: false, preset: 'flat', params: {}, irRef: null },
  parallelSaves: 4,         // offline saves running at once (Settings → Offline cache)
  density: 'comfortable',   // 'comfortable' | 'compact'
  perfMode: false,          // disable heavy visual effects for speed
@@ -673,7 +675,24 @@ const DEFAULT_SETTINGS = {
  autoBackupIntervalDays: 7,
  serviceVideo: false,      // show the video panel inside service mode (lyric videos)
 };
-let data = { playlists: [], history: [], queue: [], customVideos: [], pinnedPlaylists: [], settings: { ...DEFAULT_SETTINGS }, resumePositions: {}, rememberPos: {}, playCount: {}, abMarkers: {}, bookmarks: {}, lyricOffsets: {}, stats: null, lastAutoBackup: 0, profile: null };
+function normalizeJamesDspSettings(settings) {
+  const saved = settings?.jamesDsp && typeof settings.jamesDsp === 'object' ? settings.jamesDsp : {};
+  const params = saved.params && typeof saved.params === 'object' && !Array.isArray(saved.params) ? { ...saved.params } : {};
+  // Impulse-response PCM is intentionally session-only; do not re-enable the
+  // convolver on a later boot without its uploaded audio buffer.
+  const irRef = saved.irRef && typeof saved.irRef.name === 'string' && typeof saved.irRef.hash === 'string'
+    ? { name: saved.irRef.name, hash: saved.irRef.hash } : null;
+  if (!irRef) delete params['convolver.enabled'];
+  settings.jamesDsp = {
+    enabled: saved.enabled === true,
+    downloadForOffline: saved.downloadForOffline === true,
+    preset: typeof saved.preset === 'string' ? saved.preset : 'flat',
+    params,
+    irRef,
+  };
+  return settings;
+}
+let data = { playlists: [], history: [], queue: [], customVideos: [], pinnedPlaylists: [], settings: normalizeJamesDspSettings({ ...DEFAULT_SETTINGS }), resumePositions: {}, rememberPos: {}, playCount: {}, abMarkers: {}, bookmarks: {}, lyricOffsets: {}, stats: null, lastAutoBackup: 0, profile: null };
 let view = { type: 'search' };          // 'search'|'history'|'playlist'|'settings'|'queue'|'saved'|'downloads'|'channel'
 let searchResults = [];
 // Distinguishes "never searched" (hide the list pane, show the landing) from
@@ -696,6 +715,8 @@ const IS_IOS = /iPad|iPhone|iPod/.test(navigator.userAgent) || (navigator.platfo
 let _currentEqUrl = null;
 async function useEqRender(id) {
  if (_currentEqUrl) { URL.revokeObjectURL(_currentEqUrl); _currentEqUrl = null; }
+  // JamesDSP is a live insert: never layer it over the Standard renderer copy.
+  if (data.settings?.jamesDsp?.enabled) return null;
  if (typeof EqRender === 'undefined' || !WEB) return null;
  try { _currentEqUrl = await EqRender.urlFor(id); } catch { _currentEqUrl = null; }
  return _currentEqUrl;
@@ -906,7 +927,7 @@ function applyProfileData(name, payload, updatedAt) {
  if (payload.bookmarks && typeof payload.bookmarks === 'object') data.bookmarks = payload.bookmarks;
  if (payload.lyricOffsets && typeof payload.lyricOffsets === 'object') data.lyricOffsets = payload.lyricOffsets;
  if (payload.stats && typeof payload.stats === 'object') data.stats = payload.stats;
-  if (payload.settings && typeof payload.settings === 'object') data.settings = { ...DEFAULT_SETTINGS, ...payload.settings };
+  if (payload.settings && typeof payload.settings === 'object') data.settings = normalizeJamesDspSettings({ ...DEFAULT_SETTINGS, ...payload.settings });
  data.profile = { name, syncedAt: updatedAt || 0, protected: !!payload.__protected, kind: payload.__kind || null };
  API.saveData(data).catch(() => {});
 }
@@ -1978,20 +1999,6 @@ function markCardCacheState(id, state) {
  });
 }

-// Auto-save what you play: once a video starts playing, save it in the
-// background (never delays playback). One attempt per video per page session.
-const autoSaveTried = new Set();
-document.addEventListener('play', () => {
-  const m = current && current.meta;
-  if (!m || !m.id || m.custom || current.localUrl) return;
-  if (data.settings.autoSavePlayed === false) return;
-  if (!WEB) return;
-  if (cachedIds.has(m.id) || downloading.has(m.id) || autoSaveTried.has(m.id)) return;
-  autoSaveTried.add(m.id);
-  preload(m, { quiet: true });
-}, true);
-
-
 // ============================================================================
 // Video editor — cut parts out of a video and save a custom offline copy
 //
@@ -3349,6 +3356,20 @@ function openMoreActions() {
    row.onclick = () => { closeModal(); setTimeout(() => src.click(), 0); };
    list.appendChild(row);
  }
+  if (data.settings?.jamesDsp?.enabled && EQ.state().jamesDsp?.active) {
+    const row = document.createElement('button');
+    row.type = 'button'; row.className = 'more-row';
+    const bypassed = !!EQ.state().jamesDsp?.bypassed;
+    row.innerHTML = '<span class="more-ico" aria-hidden="true">A/B</span><span class="more-txt"><b></b><small>Temporarily compare with the unprocessed signal</small></span><span class="more-go">›</span>';
+    row.querySelector('b').textContent = bypassed ? 'Resume JamesDSP' : 'Bypass JamesDSP';
+    row.setAttribute('aria-label', row.querySelector('b').textContent);
+    row.onclick = async () => {
+      closeModal();
+      const next = await EQ.toggleDspBypass();
+      toast(next ? 'JamesDSP bypassed' : 'JamesDSP active');
+    };
+    list.appendChild(row);
+  }
  if (!list.children.length) { toast('No more actions for this video'); return; }
  showModal('More actions', list, [{ label: 'Close', onClick: closeModal }]);
 }
@@ -5349,7 +5370,7 @@ const Level = (() => {
 // so it keeps going when locked. One render at a time, in the background.
 const EqRender = (() => {
  const DIR = 'eq-renders', KEY = 'ytpEqRenders', RATE = 32000, MAX_SECONDS = 12 * 60;
-  const active = () => EQ.isIOS() && WEB && !!window.OPFS && window.OPFS.isSupported() && typeof OfflineAudioContext !== 'undefined';
+  const active = () => EQ.isIOS() && WEB && !data.settings?.jamesDsp?.enabled && !!window.OPFS && window.OPFS.isSupported() && typeof OfflineAudioContext !== 'undefined';
  const readMap = () => { try { return JSON.parse(localStorage.getItem(KEY) || '{}'); } catch { return {}; } };
  const writeMap = (m) => { try { localStorage.setItem(KEY, JSON.stringify(m)); } catch { /* blocked */ } };
  const queue = new Set();
@@ -5519,10 +5540,13 @@ const PiP = (() => {
 const loadSoundFeatures=()=>Promise.all([Lazy.load('feature:eq-core'),Lazy.load('feature:vocal-reducer')]);
 const EQ_BANDS = EqParameters.bands;
 const EQ_PRESETS = EqParameters.presets;
+const JamesDSPFeature = Lazy.proxy('feature:jamesdsp', ['createController'], 'JamesDSPFeature');
+const JamesDSPTools = Lazy.proxy('feature:jamesdsp', ['generateIR', 'decodeIR', 'prepareIR', 'saveIR', 'getIR', 'listIRs', 'deleteIR'], 'JamesDSPFeature');
 const EQ = (() => {
  const isIOS = /iPad|iPhone|iPod/.test(navigator.userAgent) || (navigator.platform === 'MacIntel' && navigator.maxTouchPoints > 1);
  const AC = window.AudioContext || window.webkitAudioContext;
-  const st = { ctx: null, filters: null, sources: new Map() };
+  const st = { ctx: null, filters: null, levelDb: 0 };
+  let dspController = null, dspControllerPromise = null, dspRequest = 0;
  // Web Audio is off on iOS (it silences playback when the screen locks)
  // unless the user opted in through "Level volume" (Settings → Playback).
  // Live Web Audio is off on iOS (it silences playback when the screen locks)
@@ -5537,6 +5561,49 @@ const EQ = (() => {
  };
  const isFlat = () => gains().every((v) => v === 0);

+  async function prepareDspGraph() {
+    if (!available()) throw new Error(isIOS ? 'Turn on Live sound processing in Settings → Playback first.' : 'Web Audio is unavailable.');
+    if (rendered()) throw new Error('This song is already playing a Standard processed copy. JamesDSP will start with the next original track.');
+    if (!st.ctx && !AudioGraph.snapshot().contextCreated) {
+      const context = AudioGraph.context({ sampleRate: 48000 });
+      if (context.state === 'suspended') context.resume().catch(() => {});
+    }
+    await loadSoundFeatures();
+    if (!st.ctx && !build()) throw new Error('The Standard fallback audio chain is not ready.');
+    if (!st.ctx || !st.filters?.[0]) throw new Error('The Standard fallback audio chain could not be built.');
+    attach(els.video);
+    attach(els.audio);
+    return { context: st.ctx, elements: [els.video, els.audio].filter(Boolean), standardInput: st.filters[0] };
+  }
+
+  function dspFailed(error) {
+    if (!data.settings.jamesDsp?.enabled) return;
+    data.settings.jamesDsp.enabled = false;
+    if ($('setSoundEngine')) $('setSoundEngine').value = 'standard';
+    if ($('jamesDspControls')) $('jamesDspControls').hidden = true;
+    persist();
+    toast(`JamesDSP unavailable; Standard sound is active. ${error?.message || ''}`.trim());
+    apply();
+    Level.apply();
+  }
+
+  async function getDspController() {
+    if (dspController) return dspController;
+    if (!dspControllerPromise) dspControllerPromise = Lazy.load('feature:jamesdsp').then(async () => {
+      dspController = await JamesDSPFeature.createController({ graph: AudioGraph, prepareGraph: prepareDspGraph, onError: dspFailed });
+      return dspController;
+    }).catch(error => { dspControllerPromise = null; throw error; });
+    return dspControllerPromise;
+  }
+
+  function startDsp() {
+    const request = ++dspRequest;
+    getDspController().then(controller => {
+      if (request !== dspRequest || !data.settings.jamesDsp?.enabled) return controller.disable();
+      return controller.enable(data.settings.jamesDsp, st.levelDb);
+    }).catch(dspFailed);
+  }
+
  function build() {
    if (st.ctx) return true;
    if (!Lazy.loaded('feature:eq-core') || !Lazy.loaded('feature:vocal-reducer')) {
@@ -5544,7 +5611,7 @@ const EQ = (() => {
      return false;
    }
    try {
-      st.ctx = new AC();
+      st.ctx = AudioGraph.context();
      st.filters = EQ_BANDS.map((b) => {
        const f = st.ctx.createBiquadFilter();
        f.type = b.type;
@@ -5569,16 +5636,24 @@ const EQ = (() => {
  }

  function attach(el) {
-    if (!el || st.sources.has(el)) return;
+    if (!el) return;
    try {
-      const src = st.ctx.createMediaElementSource(el);
-      src.connect(st.filters[0]);
-      st.sources.set(el, src);
+      AudioGraph.connect(el, st.filters[0]);
    } catch { /* already connected elsewhere */ }
  }

  // Apply the stored curve; wires the graph up the first time it's non-flat.
  function apply() {
+    if (data.settings.jamesDsp?.enabled) {
+      if (!available()) { dspFailed(new Error(isIOS ? 'Live sound processing is off on this iPhone.' : 'Web Audio is unavailable.')); return; }
+      if (rendered()) { dspFailed(new Error('The current song already uses a Standard processed copy.')); return; }
+      startDsp();
+      renderButton();
+      return;
+    }
+    dspRequest++;
+    if (dspController) dspController.disable().catch(() => {});
+    else if (dspControllerPromise) dspControllerPromise.then(controller => controller.disable()).catch(() => {});
    if (!available()) return;
    if (!st.ctx && isFlat() && EqParameters.amount(data.settings.vocalLevel ?? 100) === 100 && EqParameters.width(data.settings.stereoWidth) === 0) return;
    if (!build()) return;
@@ -5658,6 +5733,7 @@ const EQ = (() => {
  // one-way step the EQ takes, so it is only offered where the EQ is (never
  // on iOS, where Web Audio would silence background playback).
  function analyser() {
+    if (dspController?.active && !dspController.state().bypassed) return dspController.analyser();
    if (!available() || !build()) return null;
    attach(els.video);
    attach(els.audio);
@@ -5673,8 +5749,13 @@ const EQ = (() => {

  // Set the levelling gain (dB). 0 dB never wires the graph on its own.
  function setLevel(db) {
-    if (!available()) return false;
    if (rendered()) db = 0;
+    st.levelDb = Number(db) || 0;
+    if (data.settings.jamesDsp?.enabled) {
+      if (dspController?.desired) dspController.setLevelDb(st.levelDb).catch(dspFailed);
+      return true;
+    }
+    if (!available()) return false;
    if (!st.ctx && Math.abs(db) < 0.3) return true;
    if (!build()) return false;
    attach(els.video);
@@ -5685,8 +5766,56 @@ const EQ = (() => {
    return true;
  }

+  async function toggleDspBypass() {
+    if (!dspController?.active) return false;
+    try { return await dspController.toggleBypass(); }
+    catch (error) { dspFailed(error); return false; }
+  }
+
+  function dspLowEndDevice() {
+    const cores=Number(navigator.hardwareConcurrency), memory=Number(navigator.deviceMemory);
+    return (cores>0&&cores<=4)||(memory>0&&memory<=4);
+  }
+
+  async function loadDspIRBuffer(buffer, reference=null) {
+    if (!data.settings.jamesDsp?.enabled || !dspController?.active) throw new Error('Turn on JamesDSP before importing an impulse response.');
+    await dspController.loadIR(buffer,reference);
+    data.settings.jamesDsp.irRef=reference;
+    data.settings.jamesDsp.params['convolver.enabled']=1;
+    persist();
+    return reference;
+  }
+
+  async function loadDspIR(file) {
+    if (!data.settings.jamesDsp?.enabled || !dspController?.active) throw new Error('Turn on JamesDSP before importing an impulse response.');
+    const context=st.ctx;if(!context?.decodeAudioData)throw new Error('Audio decoding is unavailable on this device.');
+    const buffer=await context.decodeAudioData(await file.arrayBuffer());
+    const prepared=await JamesDSPTools.prepareIR(context,buffer,dspLowEndDevice()?24000:65536);
+    const name=String(file.name||'Uploaded IR').replace(/\.[^.]+$/,'').slice(0,100)||'Uploaded IR';
+    let reference=null;try{reference=await JamesDSPTools.saveIR(name,prepared,{kind:'uploaded'});}catch(error){toast(`Impulse response stays on this device for this session: ${error.message}`);}
+    return loadDspIRBuffer(prepared,reference);
+  }
+
+  async function loadDspBuiltinIR(name) {
+    if(!data.settings.jamesDsp?.enabled||!dspController?.active)throw new Error('Turn on JamesDSP before loading an impulse response.');
+    const context=st.ctx;if(!context)throw new Error('Audio context is unavailable.');
+    const lowEnd=dspLowEndDevice();if(lowEnd&&name!=='Small room')throw new Error('Long impulse responses are disabled on this lower-power device.');
+    const buffer=await JamesDSPTools.generateIR(name,context.sampleRate,2,lowEnd?24000:65536);
+    let reference=null;try{reference=await JamesDSPTools.saveIR(name,buffer,{kind:'generated'});}catch(error){toast(`Generated response stays in this session: ${error.message}`);}
+    return loadDspIRBuffer(buffer,reference);
+  }
+
+  async function loadDspSavedIR(name) {
+    const stored=await JamesDSPTools.getIR(name);if(!stored)throw new Error(`Stored impulse response not found: ${name}`);
+    return loadDspIRBuffer(stored.buffer,{name:stored.name,hash:stored.hash});
+  }
+
+  async function listDspIRs() {
+    return JamesDSPTools.listIRs();
+  }
+
  return { open, apply, renderButton, available, analyser, setLevel, gains, bands: EQ_BANDS, isIOS: () => isIOS, state: () => ({ wired: !!st.ctx, ctx: st.ctx && st.ctx.state, gains: st.filters ? st.filters.map((f) => f.gain.value) : null,
-    levelDb: st.level ? Math.round(200 * Math.log10(Math.max(1e-6, st.level.gain.value))) / 10 : null }) };
+    levelDb: st.level ? Math.round(200 * Math.log10(Math.max(1e-6, st.level.gain.value))) / 10 : null, jamesDsp: dspController?.state() || null }), toggleDspBypass, loadDspIR, loadDspIRBuffer, loadDspBuiltinIR, loadDspSavedIR, listDspIRs };
 })();

 // ============================================================================
@@ -8539,9 +8668,7 @@ const RUNNING_BUILD = (() => {
 let _knownBuildTag = null;

 async function fetchServerBuild() {
-  const res = await fetch('/api/version', { cache: 'no-store' });
-  if (!res.ok) return null;
-  const data = await res.json();
+  const data = await webFetch('/api/version', { cache: 'no-store' });
  return data.buildTag || null;
 }

@@ -8769,6 +8896,8 @@ async function registerServiceWorker() {
    const reg = await navigator.serviceWorker.register('/sw.js', { updateViaCache: 'none' });
    _swReg = reg;
    Lazy.reportLayout(reg);
+    reportDspOfflineOptIn(reg);
+    navigator.serviceWorker.ready.then(readyReg => reportDspOfflineOptIn(readyReg)).catch(() => {});

    // A waiting worker only means "update pending" when this page is already
    // controlled by a previous SW. On a FIRST install (fresh visit, or right
@@ -8804,6 +8933,14 @@ async function registerServiceWorker() {
  }
 }

+function reportDspOfflineOptIn(reg = _swReg) {
+  if (!WEB || !navigator.serviceWorker) return;
+  const dsp = data.settings?.jamesDsp;
+  const values = dsp?.enabled || dsp?.downloadForOffline ? ['jamesDsp'] : [];
+  const workers = new Set([navigator.serviceWorker.controller, reg?.installing, reg?.active, reg?.waiting]);
+  for (const worker of workers) worker?.postMessage({ type: 'OFFLINE_OPT_INS', values });
+}
+
 // /?q=<query> — a shareable search link (same family as Share's /?v=&t=).
 // Runs after wireUI() so the search form's submit handler exists; the param
 // is stripped immediately so a reload doesn't re-run the search.
@@ -8983,7 +9120,7 @@ async function boot() {
        lyricOffsets: loaded.lyricOffsets || {},
        stats: loaded.stats || null,
        lastAutoBackup: loaded.lastAutoBackup || 0,
-        settings: { ...DEFAULT_SETTINGS, ...(loaded.settings || {}) },
+        settings: normalizeJamesDspSettings({ ...DEFAULT_SETTINGS, ...(loaded.settings || {}) }),
        profile: loaded.profile || null,
      };
    }
--- a/frontend/asset-sync-core.js
+++ b/frontend/asset-sync-core.js
@@ -3,12 +3,22 @@
  'use strict';
  const CACHE = 'ytplayer-assets';
  const STATE = '/__ytp_asset_state';
+  const OPT_INS = '/__ytp_offline_opt_ins';
  const url = (path, file) => path + '?v=' + file.h;

  function paths(manifest) {
    return Object.keys(manifest.files).sort();
  }

+  function offlinePaths(manifest, optIns = []) {
+    const allowed = new Set(optIns || []), optional = new Map();
+    for (const group of Object.values(manifest.groups || {})) {
+      if (!group.offlineOptIn || allowed.has(group.offlineOptIn)) continue;
+      for (const path of group.files || []) optional.set(path, true);
+    }
+    return paths(manifest).filter(path => !optional.has(path));
+  }
+
  function blocking(manifest, previous, activeLayout) {
    const names = new Set(Object.entries(manifest.groups)
      .filter(([name, group]) => name === 'core' || !group.background ||
@@ -61,13 +71,17 @@
    return valid;
  }

-  async function status(manifest, cache, { previous, activeLayout, offline = true } = {}) {
+  async function readOptIns(cache) {
+    try { return (await (await cache.match(OPT_INS))?.json()) || []; } catch { return []; }
+  }
+
+  async function status(manifest, cache, { previous, activeLayout, offline = true, optIns } = {}) {
    const found = await Promise.all(blocking(manifest, previous, activeLayout).map(async path => {
      const response = await cache.match(url(path, manifest.files[path]));
      return verifiedProbe(response, manifest.files[path].h);
    }));
    const missing = found.filter(value => !value).length;
-    return { ready: missing === 0, missing, version: manifest.buildTag, ...(offline ? await completeness(manifest, cache) : {}) };
+    return { ready: missing === 0, missing, version: manifest.buildTag, ...(offline ? await completeness(manifest, cache, { optIns }) : {}) };
  }

  // All concurrent messages/layout jobs in this worker share six download slots.
@@ -89,10 +103,10 @@
    finally { pendingDownloads.delete(key); }
  }

-  async function syncAssets(manifest, { cache, fetchFn, concurrency = 6, attempts = 3, activeLayout, groups, all = false }) {
+  async function syncAssets(manifest, { cache, fetchFn, concurrency = 6, attempts = 3, activeLayout, groups, all = false, optIns } = {}) {
    const previous = (await state(cache))?.current;
    const missing = [];
-    const selected = all ? paths(manifest) : groups ? [...new Set(groups.flatMap(name => manifest.groups[name]?.files || []))].sort()
+    const selected = all ? offlinePaths(manifest, optIns || await readOptIns(cache)) : groups ? [...new Set(groups.flatMap(name => manifest.groups[name]?.files || []))].sort()
      : blocking(manifest, previous, activeLayout);
    for (const path of selected) {
      const key = url(path, manifest.files[path]);
@@ -135,8 +149,8 @@

  // Verified cache entries are the durable progress journal. Counters are rebuilt
  // after worker termination or browser eviction; never trust a stored ready bit.
-  async function completeness(manifest, cache) {
-    const files = paths(manifest);
+  async function completeness(manifest, cache, { optIns } = {}) {
+    const files = offlinePaths(manifest, optIns || await readOptIns(cache));
    const missingFiles = (await Promise.all(files.map(async path => {
      const response = await cache.match(url(path, manifest.files[path]));
      return verifiedProbe(response, manifest.files[path].h) ? null : path;
@@ -146,12 +160,13 @@
  }

  const completionKey = manifest => '/__ytp_completion/' + manifest.buildTag;
-  async function complete(manifest, { cache, fetchFn, cycles = 4, now = Date.now,
+  async function complete(manifest, { cache, fetchFn, cycles = 4, now = Date.now, optIns,
    sleep = ms => new Promise(resolve => setTimeout(resolve, ms)), baseDelay = 1000,
-    maxDelay = 30000, notify = () => {}, force = false } = {}) {
+    maxDelay = 30000, notify = () => {}, force = false, concurrency = 1 } = {}) {
    const key = completionKey(manifest), saved = await cache.match(key);
    let job = saved ? await saved.json() : { failures: 0, nextRetryAt: 0 };
-    let snapshot = await completeness(manifest, cache);
+    const selectedOptIns = optIns || await readOptIns(cache);
+    let snapshot = await completeness(manifest, cache, { optIns: selectedOptIns });
    const publish = async running => {
      job = { ...job, ...snapshot, running, version: manifest.buildTag };
      await cache.put(key, Response.json(job));
@@ -162,9 +177,9 @@
    for (let cycle = 0; cycle < cycles; cycle++) {
      await publish(true);
      let error;
-      try { await syncAssets(manifest, { cache, fetchFn, all: true }); }
+      try { await syncAssets(manifest, { cache, fetchFn, all: true, optIns: selectedOptIns, concurrency }); }
      catch (failure) { error = failure; }
-      snapshot = await completeness(manifest, cache);
+      snapshot = await completeness(manifest, cache, { optIns: selectedOptIns });
      if (snapshot.offlineReady) { job.failures = 0; job.nextRetryAt = 0; job.error = null; await publish(false); return job; }
      job.failures++;
      const delay = Math.min(maxDelay, baseDelay * 2 ** Math.min(job.failures - 1, 10));
@@ -198,7 +213,7 @@
    return next;
  }

-  const api = { CACHE, STATE, url, paths, blocking, plan, retained, fallback, status, completeness, completionKey, complete, syncAssets, state, commit };
+  const api = { CACHE, STATE, OPT_INS, url, paths, offlinePaths, blocking, plan, retained, fallback, status, completeness, completionKey, complete, syncAssets, readOptIns, state, commit };
  if (typeof module !== 'undefined' && module.exports) module.exports = api;
  else root.AssetSyncCore = api;
 })(typeof globalThis !== 'undefined' ? globalThis : this);
--- a/frontend/asset-sync-core.test.js
+++ b/frontend/asset-sync-core.test.js
@@ -56,6 +56,20 @@ test('completion includes ungrouped runtime files and exposes verified missing p
 assert.equal((await core.status(m,c)).offlineReady,true);
 });

+test('offline completion skips opt-in DSP assets until the user enables offline audio effects', async () => {
+ const c=cache(),m=manifest();m.files['/vendor/jamesdsp/dsp/jamesdsp.wasm']={h:'wasm'};
+ m.groups.jamesdsp={contract:1,eager:false,background:true,offlineOptIn:'jamesDsp',files:['/vendor/jamesdsp/dsp/jamesdsp.wasm']};
+ const calls=[];
+ const defaultJob=await core.complete(m,{cache:c,fetchFn:async u=>{calls.push(u);return response(u.split('=')[1])}});
+ assert.deepEqual(calls.sort(),['/a.js?v=a','/index.html?v=b']);
+ assert.equal(defaultJob.total,2);assert.equal(defaultJob.offlineReady,true);
+ calls.length=0;
+ await c.put(core.OPT_INS,Response.json(['jamesDsp']));
+ const optedJob=await core.complete(m,{cache:c,fetchFn:async u=>{calls.push(u);return response(u.split('=')[1])}});
+ assert.deepEqual(calls,['/vendor/jamesdsp/dsp/jamesdsp.wasm?v=wasm']);
+ assert.equal(optedJob.total,3);assert.equal(optedJob.offlineReady,true);
+});
+
 test('completion persists backoff and resumes only missing files after a worker restart',async()=>{
 const c=cache(),m=manifest();let clock=1000;const calls=[];
 await core.complete(m,{cache:c,cycles:1,now:()=>clock,baseDelay:10,fetchFn:async u=>{if(u.includes('index'))throw Error('offline');return response('a');}});
@@ -82,6 +96,13 @@ test('overlapping layout and completion jobs share a six-download ceiling',async
 assert.ok(peak<=6);assert.ok([...calls.values()].every(count=>count===1));
 });

+test('offline completion keeps its own network concurrency to one',async()=>{
+ const c=cache(),m=manifest();let active=0,peak=0;
+ for(let i=0;i<12;i++){const p='/complete'+i+'.js';m.files[p]={h:String(i)};}
+ const fetchFn=async u=>{active++;peak=Math.max(peak,active);await new Promise(r=>setTimeout(r,2));active--;return response(u.split('=')[1]);};
+ await core.complete(m,{cache:c,fetchFn});assert.equal(peak,1);
+});
+
 test('blocking commit never waits on an optional file readiness probe',{timeout:1000},async()=>{
 const c=cache(),m=manifest();m.files['/extra.js']={h:'extra'};m.groups.extra={files:['/extra.js'],background:true,contract:1};
 await c.put('/a.js?v=a',response('a'));await c.put('/index.html?v=b',response('b'));
--- a/frontend/asset-worker.test.js
+++ b/frontend/asset-worker.test.js
@@ -57,6 +57,31 @@ test('waiting status does not start completion and activation delegates it to it
 assert.equal((await core.status(e.m,cache)).offlineReady,true);
 });

+test('legacy shell verification is staged during install so Refresh UI activation does no hashing',async()=>{
+ const e=environment(),legacy=await e.storage.open('ytplayer-production-old');let digests=0;
+ await legacy.put('/app.js',new Response('legacy app bytes'));
+ const subtle=e.sandbox.crypto.subtle;
+ e.sandbox.crypto={subtle:{digest:async(...args)=>{digests++;return subtle.digest(...args);}}};
+ await e.dispatch('install');
+ const stagedDigests=digests,cache=await e.storage.open(core.CACHE),candidate=await(await cache.match('/__ytp_candidate/next')).json();
+ assert.ok(stagedDigests>0,'install verified old cached bytes before offering Refresh UI');
+ assert.deepEqual(candidate.legacyCacheNames,['ytplayer-production-old']);
+ assert.ok((await core.state(cache)).current.legacyURLs['/app.js']);
+ await e.dispatch('activate');
+ assert.equal(digests,stagedDigests,'the user-triggered activation does not hash the old shell again');
+ assert.equal((await e.storage.keys()).includes('ytplayer-production-old'),false,'old shell is deleted only after commit');
+});
+
+test('offline opt-in is persisted and adds only declared optional groups to completion',async()=>{
+ const e=environment();e.m.files['/large.wasm']={h:'wasm'};e.m.groups.dsp={files:['/large.wasm'],contract:1,background:true,offlineOptIn:'jamesDsp'};
+ await e.dispatch('install');await e.dispatch('activate');await e.complete();
+ const cache=await e.storage.open(core.CACHE);assert.equal(await cache.match('/large.wasm?v=wasm'),undefined);
+ await e.dispatch('message',{data:{type:'OFFLINE_OPT_INS',values:['jamesDsp','not-a-valid-opt-in']}});
+ assert.deepEqual(await core.readOptIns(cache),['jamesDsp']);
+ assert.equal((await cache.match('/large.wasm?v=wasm')).headers.get('X-Asset-Hash'),'wasm');
+ const status=await core.status(e.m,cache);assert.equal(status.offlineReady,true);assert.equal(status.total,3);
+});
+
 test('page-captured app is reused on first install without a worker download',async()=>{
 const e=environment(),cache=await e.storage.open(core.CACHE);
 await cache.put('/app.js?v=app',new Response('page captured app',{headers:{'X-Asset-Hash':'app'}}));
--- a/frontend/assets.json
+++ b/frontend/assets.json
@@ -29,6 +29,7 @@
        "/related-videos.js",
        "/related-videos.css",
        "/audio-continuity.js",
+        "/audio-graph.js",
        "/fullscreen-orientation.js",
        "/fullscreen-orientation.css",
        "/download-actions.js",
@@ -359,6 +360,27 @@
      "dependencies": [
        "feature:stats"
      ]
+    },
+    "feature:jamesdsp": {
+      "contract": 1,
+      "eager": false,
+      "background": true,
+      "offlineOptIn": "jamesDsp",
+      "files": [
+        "/vendor/jamesdsp/jamesdsp-feature.js",
+        "/vendor/jamesdsp/jamesdsp-node.mjs",
+        "/vendor/jamesdsp/params.mjs",
+        "/vendor/jamesdsp/ir-utils.mjs",
+        "/vendor/jamesdsp/ir-builtins.mjs",
+        "/vendor/jamesdsp/ir-store.mjs",
+        "/vendor/jamesdsp/worklet.mjs",
+        "/vendor/jamesdsp/dsp/jamesdsp-a982b53.mjs",
+        "/vendor/jamesdsp/dsp/jamesdsp.wasm"
+      ],
+      "dependencies": [
+        "feature:eq-core",
+        "feature:vocal-reducer"
+      ]
    }
  }
 }
--- a/frontend/async-guard.js
+++ b/frontend/async-guard.js
@@ -35,7 +35,68 @@
    }
  }

-  const AsyncGuard = { runExclusive };
+  const wait = ms => new Promise(resolve => setTimeout(resolve, ms));
+  async function retry(task, { attempts = 3, delay = attempt => attempt === 1 ? 350 : 1000,
+    shouldRetry = () => true, sleep = wait } = {}) {
+    let last;
+    for (let attempt = 1; attempt <= Math.max(1, attempts); attempt++) {
+      try { return await task(attempt); }
+      catch (error) {
+        last = error;
+        if (attempt >= attempts || !shouldRetry(error, attempt)) throw error;
+        await sleep(delay(attempt));
+      }
+    }
+    throw last;
+  }
+
+  // Retry only idempotent GETs. Keep the timeout active through JSON parsing so
+  // a stalled response body is treated like a stalled connection.
+  async function getJson(url, options = {}, config = {}) {
+    const fetchFn = config.fetch || root.fetch?.bind(root);
+    if (!fetchFn) throw new Error('fetch is unavailable');
+    if ((options.method || 'GET').toUpperCase() !== 'GET') throw new Error('Retry helper only accepts GET');
+    const attempts = config.attempts ?? 3, timeoutMs = config.timeoutMs ?? 20000;
+    return retry(async () => {
+      const controller = typeof AbortController === 'function' ? new AbortController() : null;
+      let timedOut = false, timer, externalAbort;
+      const external = options.signal;
+      if (controller && external) {
+        if (external.aborted) throw external.reason || new DOMException('Aborted', 'AbortError');
+        externalAbort = () => controller.abort(external.reason);
+        external.addEventListener('abort', externalAbort, { once: true });
+      }
+      if (controller && timeoutMs > 0) timer = setTimeout(() => { timedOut = true; controller.abort(); }, timeoutMs);
+      try {
+        const response = await fetchFn(url, { ...options, ...(controller ? { signal: controller.signal } : {}) });
+        if ([408, 425, 429].includes(response.status) || response.status >= 500) {
+          const error = new Error(`HTTP ${response.status}`); error.retryable = true; throw error;
+        }
+        if (!response.ok) {
+          let message = `HTTP ${response.status}`;
+          try { message = (await response.json()).error || message; } catch {}
+          const error = new Error(message); error.retryable = false; throw error;
+        }
+        const value = await response.json();
+        if (config.retryResult?.(value)) {
+          const error = new Error(value.error || value.message || 'Temporary API failure');
+          error.retryable = true;
+          throw error;
+        }
+        return value;
+      } catch (error) {
+        if (external?.aborted) throw error;
+        if (timedOut) { const timeout = new Error('Request timed out'); timeout.retryable = true; throw timeout; }
+        if (error.retryable === undefined) error.retryable = true;
+        throw error;
+      } finally {
+        if (timer) clearTimeout(timer);
+        if (external && externalAbort) external.removeEventListener('abort', externalAbort);
+      }
+    }, { attempts, shouldRetry: error => error.retryable !== false, sleep: config.sleep || wait });
+  }
+
+  const AsyncGuard = { runExclusive, retry, getJson };

  if (typeof module !== 'undefined' && module.exports) {
    module.exports = AsyncGuard;
--- a/frontend/async-guard.test.js
+++ b/frontend/async-guard.test.js
@@ -60,6 +60,55 @@ test('frees the key after failure so a retry is possible', async () => {
  assert.strictEqual(out, 'ok');
 });

+test('bounded GET retries recover transient network and server failures', async () => {
+  const { getJson } = require('./async-guard');
+  let calls = 0;
+  const result = await getJson('/api/search', {}, { sleep: async () => {}, fetch: async () => {
+    calls++;
+    if (calls === 1) throw new TypeError('connection reset');
+    if (calls === 2) return new Response('{}', { status: 503 });
+    return Response.json({ ok: true, results: [] });
+  } });
+  assert.equal(result.ok, true);
+  assert.equal(calls, 3);
+});
+
+test('GET retry stops at the bound and does not retry permanent HTTP errors', async () => {
+  const { getJson } = require('./async-guard');
+  let calls = 0;
+  await assert.rejects(getJson('/api/search', {}, { sleep: async () => {}, fetch: async () => {
+    calls++; return new Response('{}', { status: 404 });
+  } }), /HTTP 404/);
+  assert.equal(calls, 1);
+  await assert.rejects(getJson('/api/search', {}, { attempts: 2, sleep: async () => {}, fetch: async () => {
+    calls++; throw new TypeError('offline');
+  } }), /offline/);
+  assert.equal(calls, 3);
+});
+
+test('retryable API error payloads recover but permanent application errors do not retry', async () => {
+  const { getJson } = require('./async-guard'); let calls = 0;
+  const retryResult = value => value?.ok === false && /temporarily unavailable/i.test(value.error || '');
+  const result = await getJson('/api/streams', {}, { retryResult, sleep: async () => {}, fetch: async () => {
+    calls++;
+    return Response.json(calls === 1 ? { ok: false, error: 'temporarily unavailable' } : { ok: true, data: [] });
+  } });
+  assert.equal(result.ok, true); assert.equal(calls, 2);
+  calls = 0;
+  const absent = await getJson('/api/streams', {}, { retryResult, sleep: async () => {}, fetch: async () => { calls++; return Response.json({ ok: false, error: 'video not found' }); } });
+  assert.equal(absent.ok, false); assert.equal(calls, 1);
+});
+
+test('timed out GET bodies retry within the configured bound', async () => {
+  const { getJson } = require('./async-guard'); let calls = 0;
+  const result = await getJson('/api/related', {}, { attempts: 2, timeoutMs: 5, sleep: async () => {}, fetch: async (_url, { signal }) => {
+    calls++;
+    if (calls === 1) return new Promise((resolve, reject) => signal.addEventListener('abort', () => reject(new DOMException('aborted', 'AbortError')), { once: true }));
+    return Response.json({ ok: true });
+  } });
+  assert.equal(result.ok, true); assert.equal(calls, 2);
+});
+
 test('supports a synchronous fn', async () => {
  const set = new Set();
  const out = await runExclusive(set, 's', () => 7);
--- a/frontend/audio-graph.js
+++ b/frontend/audio-graph.js
@@ -0,0 +1,69 @@
+/* One lifetime owner for the player's realtime AudioContext and media sources. */
+(function (root) {
+  'use strict';
+
+  function create(options = {}) {
+    const getConstructor = options.getConstructor || (() => root.AudioContext || root.webkitAudioContext);
+    let context = null;
+    const sources = new Map();
+    const routes = new Map();
+    const failed = new Map();
+
+    function getContext(contextOptions) {
+      if (context) return context;
+      const Constructor = getConstructor();
+      if (typeof Constructor !== 'function') throw new Error('Web Audio is unavailable');
+      context = contextOptions === undefined ? new Constructor() : new Constructor(contextOptions);
+      return context;
+    }
+
+    function source(element) {
+      if (!element) throw new TypeError('A media element is required');
+      if (sources.has(element)) return sources.get(element);
+      if (failed.has(element)) throw failed.get(element);
+      try {
+        const created = getContext().createMediaElementSource(element);
+        sources.set(element, created);
+        return created;
+      } catch (error) {
+        // MediaElementSource cannot be undone. Remember failure so a later
+        // route change can never attempt a second source for this element.
+        failed.set(element, error);
+        throw error;
+      }
+    }
+
+    function connect(element, destination) {
+      const mediaSource = source(element);
+      if (!destination) throw new TypeError('An audio destination is required');
+      if (routes.get(element) === destination) return mediaSource;
+      if (routes.has(element)) mediaSource.disconnect();
+      mediaSource.connect(destination);
+      routes.set(element, destination);
+      return mediaSource;
+    }
+
+    function routeAll(elements, destination) {
+      for (const element of elements || []) connect(element, destination);
+    }
+
+    function snapshot() {
+      return {
+        contextCreated: !!context,
+        sampleRate: context?.sampleRate || null,
+        sourceCount: sources.size,
+        failedCount: failed.size,
+        routedCount: routes.size,
+      };
+    }
+
+    return { context: getContext, source, connect, routeAll, snapshot };
+  }
+
+  const singleton = create();
+  const api = { create, context: (...args) => singleton.context(...args), source: (...args) => singleton.source(...args),
+    connect: (...args) => singleton.connect(...args), routeAll: (...args) => singleton.routeAll(...args),
+    snapshot: () => singleton.snapshot() };
+  if (typeof module !== 'undefined' && module.exports) module.exports = api;
+  else root.AudioGraph = api;
+})(typeof window !== 'undefined' ? window : globalThis);
--- a/frontend/audio-graph.test.js
+++ b/frontend/audio-graph.test.js
@@ -0,0 +1,75 @@
+const { test } = require('node:test');
+const assert = require('node:assert/strict');
+const { readFileSync } = require('node:fs');
+const { join } = require('node:path');
+const AudioGraph = require('./audio-graph');
+
+test('AudioGraph creates its context only on demand and retains the first context options', () => {
+  let contexts = 0, optionsSeen;
+  class Context {
+    constructor(options) { contexts++; optionsSeen = options; this.sampleRate = options?.sampleRate || 44100; }
+  }
+  const graph = AudioGraph.create({ getConstructor: () => Context });
+  assert.equal(graph.snapshot().contextCreated, false);
+  const first = graph.context({ sampleRate: 48000 });
+  assert.equal(graph.context({ sampleRate: 44100 }), first);
+  assert.equal(contexts, 1);
+  assert.deepEqual(optionsSeen, { sampleRate: 48000 });
+  assert.equal(first.sampleRate, 48000);
+});
+
+test('one retained MediaElementSource per element can change insert routes without recreation', () => {
+  const made = [], connects = [], disconnects = [];
+  class Context {
+    constructor() { this.sampleRate = 48000; }
+    createMediaElementSource(element) {
+      const source = { element, connect: target => connects.push([element.id, target.id]), disconnect: () => disconnects.push(element.id) };
+      made.push(source); return source;
+    }
+  }
+  const graph = AudioGraph.create({ getConstructor: () => Context });
+  const a = { id: 'video' }, b = { id: 'audio' }, standard = { id: 'standard' }, dsp = { id: 'dsp' };
+  const original = graph.connect(a, standard);
+  graph.connect(a, standard);
+  graph.routeAll([a, b], dsp);
+  graph.routeAll([a, b], standard);
+  assert.equal(made.length, 2);
+  assert.equal(graph.source(a), original);
+  assert.deepEqual(connects, [['video', 'standard'], ['video', 'dsp'], ['audio', 'dsp'], ['video', 'standard'], ['audio', 'standard']]);
+  assert.deepEqual(disconnects, ['video', 'video', 'audio']);
+  assert.deepEqual(graph.snapshot(), { contextCreated: true, sampleRate: 48000, sourceCount: 2, failedCount: 0, routedCount: 2 });
+});
+
+test('a failed source creation is remembered and is never attempted twice', () => {
+  let attempts = 0;
+  class Context {
+    constructor() { this.sampleRate = 48000; }
+    createMediaElementSource() { attempts++; throw new Error('already sourced'); }
+  }
+  const graph = AudioGraph.create({ getConstructor: () => Context }), element = {};
+  assert.throws(() => graph.source(element), /already sourced/);
+  assert.throws(() => graph.source(element), /already sourced/);
+  assert.equal(attempts, 1);
+  assert.deepEqual(graph.snapshot(), { contextCreated: true, sampleRate: 48000, sourceCount: 0, failedCount: 1, routedCount: 0 });
+});
+
+test('the extracted Standard EQ build block is identical to the original except for context ownership', () => {
+  const source = readFileSync(join(__dirname, 'app.js'), 'utf8');
+  const original = readFileSync(join(__dirname, '..', 'tests', 'fixtures', 'standard-eq-build.txt'), 'utf8').trimEnd();
+  const start = source.indexOf('  function build() {', source.indexOf('const EQ = (() => {'));
+  const end = source.indexOf('\n  function attach(el)', start);
+  assert.ok(start >= 0 && end > start, 'EQ build block exists');
+  const current = source.slice(start, end).trimEnd();
+  assert.equal(current, original.replace('st.ctx = new AC();', 'st.ctx = AudioGraph.context();'));
+  assert.match(source, /AudioGraph\.connect\(el, st\.filters\[0\]\)/);
+  assert.doesNotMatch(source, /\.createMediaElementSource\(/);
+});
+
+test('AudioGraph is a core runtime asset and is loaded before the lazy app', () => {
+  const { groups } = JSON.parse(readFileSync(join(__dirname, 'assets.json'), 'utf8'));
+  assert.ok(groups.core.files.includes('/audio-graph.js'));
+  const html = readFileSync(join(__dirname, 'index.html'), 'utf8');
+  assert.ok(html.indexOf('src="audio-graph.js"') < html.indexOf('src="section-rail.js"'));
+  const embedded = JSON.parse(html.match(/id="ytp-assets">([^<]+)<\/script>/)[1]);
+  assert.deepEqual(embedded.groups, groups);
+});
--- a/frontend/index.html
+++ b/frontend/index.html
--- a/frontend/jamesdsp-app.test.js
+++ b/frontend/jamesdsp-app.test.js
@@ -0,0 +1,66 @@
+const { test } = require('node:test');
+const assert = require('node:assert/strict');
+const { readFileSync } = require('node:fs');
+const { join } = require('node:path');
+const vm = require('node:vm');
+
+const app = readFileSync(join(__dirname, 'app.js'), 'utf8');
+const views = readFileSync(join(__dirname, 'views-core.js'), 'utf8');
+
+function parsePreset(text) {
+  const declaration = views.match(/function parseJamesDspPreset\(text\) \{[\s\S]*?\n\}/)?.[0];
+  assert.ok(declaration, 'preset parser is present');
+  const context = vm.createContext({});
+  vm.runInContext(`${declaration}; globalThis.parse = parseJamesDspPreset;`, context);
+  return context.parse(text);
+}
+
+test('the persisted engine is Standard by default and upgrades missing JamesDSP settings safely', () => {
+  assert.match(app, /jamesDsp: \{ enabled: false, downloadForOffline: false, preset: 'flat', params: \{\}, irRef: null \}/);
+  assert.match(app, /downloadForOffline: saved\.downloadForOffline === true/);
+  assert.match(app, /enabled: saved\.enabled === true/);
+  assert.match(app, /preset: typeof saved\.preset === 'string' \? saved\.preset : 'flat'/);
+  assert.match(app, /settings: normalizeJamesDspSettings\(\{ \.\.\.DEFAULT_SETTINGS, \.\.\.\(loaded\.settings \|\| \{\}\) \}\)/);
+  assert.match(app, /data\.settings = normalizeJamesDspSettings\(\{ \.\.\.DEFAULT_SETTINGS, \.\.\.payload\.settings \}\)/);
+});
+
+test('live JamesDSP shares the existing iOS gate and never stacks over EqRender copies', () => {
+  assert.match(app, /const available = \(\) => !!AC && \(!isIOS \|\| data\.settings\.liveAudioIOS === true\)/);
+  assert.match(app, /if \(data\.settings\?\.jamesDsp\?\.enabled\) return null/);
+  assert.match(app, /const active = \(\) => EQ\.isIOS\(\) && WEB && !data\.settings\?\.jamesDsp\?\.enabled/);
+  assert.match(app, /if \(rendered\(\)\) throw new Error\('This song is already playing a Standard processed copy\./);
+});
+
+test('EQ creates no second context or element source and passes Standard fallback routing to the controller', () => {
+  assert.equal((app.match(/\.createMediaElementSource\(/g) || []).length, 0);
+  assert.match(app, /st\.ctx = AudioGraph\.context\(\)/);
+  assert.match(app, /AudioGraph\.connect\(el, st\.filters\[0\]\)/);
+  assert.match(app, /standardInput: st\.filters\[0\]/);
+  assert.match(app, /dspController\.setLevelDb\(st\.levelDb\)/);
+  assert.match(app, /if \(data\.settings\.jamesDsp\?\.enabled\) \{[\s\S]{0,450}startDsp\(\)/);
+  assert.match(app, /request !== dspRequest \|\| !data\.settings\.jamesDsp\?\.enabled/);
+});
+
+test('Playback settings expose persisted presets, bands, safe import/export, IR, and A/B bypass', () => {
+  assert.match(views, /sel\('setSoundEngine'/);
+  assert.match(views, /sel\('setDspPreset'/);
+  for (const id of ['setDspCompressor', 'dspPresetImportBtn', 'dspPresetExportBtn', 'dspResetBtn', 'dspIrFile']) assert.ok(views.includes(`id="${id}"`), id);
+  assert.match(views, /\[25, 40, 63, 100, 160, 250, 400, 630, 1000, 1600, 2500, 4000, 6300, 10000, 16000\]/);
+  assert.match(views, /imported\?\.texts/);
+  assert.doesNotMatch(views, /liveprog|ddc|arbitrary/);
+  assert.match(views, /navigator\.hardwareConcurrency/);
+  assert.match(views, /Long impulse responses are disabled/);
+  assert.doesNotMatch(views, /44\.1 or 48 kHz/);
+  assert.match(views, /setDspSpatialMode/);
+  assert.match(views, /data-dsp-param="convolver\.predelayMs"/);
+  assert.match(views, /data-dsp-param="convolver\.mix"/);
+  assert.match(app, /Bypass JamesDSP/);
+  assert.match(app, /toggleDspBypass/);
+});
+
+test('preset import validates ranges and excludes text-effect parameters', () => {
+  assert.deepEqual(JSON.parse(JSON.stringify(parsePreset(JSON.stringify({ version: 1, preset: 'warm', params: { 'eq.band0': 3, 'bass.enabled': 1 } })))), { preset: 'warm', params: { 'eq.band0': 3, 'bass.enabled': 1 } });
+  assert.throws(() => parsePreset({ version: 1, preset: 'flat', params: { 'liveprog.enabled': 1 } }), /text effects are disabled|Unsupported preset setting/);
+  assert.throws(() => parsePreset({ version: 1, params: { 'eq.band0': 50 } }), /Unsupported preset setting/);
+  assert.throws(() => parsePreset({ version: 1, texts: { effect: 'unsafe' }, params: {} }), /text effects are disabled/);
+});
--- a/frontend/jamesdsp-assets.test.js
+++ b/frontend/jamesdsp-assets.test.js
@@ -0,0 +1,68 @@
+const { test } = require('node:test');
+const assert = require('node:assert/strict');
+const { readFileSync } = require('node:fs');
+const { join } = require('node:path');
+
+const root = __dirname;
+const assets = JSON.parse(readFileSync(join(root, 'assets.json'), 'utf8'));
+const group = assets.groups['feature:jamesdsp'];
+
+test('JamesDSP runtime files live only in a lazy background group', () => {
+  assert.ok(group, 'feature group exists');
+  assert.equal(group.contract, 1);
+  assert.equal(group.eager, false);
+  assert.equal(group.background, true);
+  assert.equal(group.offlineOptIn, 'jamesDsp');
+  assert.deepEqual(group.dependencies, ['feature:eq-core', 'feature:vocal-reducer']);
+  assert.deepEqual(group.files, [
+    '/vendor/jamesdsp/jamesdsp-feature.js',
+    '/vendor/jamesdsp/jamesdsp-node.mjs',
+    '/vendor/jamesdsp/params.mjs',
+    '/vendor/jamesdsp/ir-utils.mjs',
+    '/vendor/jamesdsp/ir-builtins.mjs',
+    '/vendor/jamesdsp/ir-store.mjs',
+    '/vendor/jamesdsp/worklet.mjs',
+    '/vendor/jamesdsp/dsp/jamesdsp-a982b53.mjs',
+    '/vendor/jamesdsp/dsp/jamesdsp.wasm',
+  ]);
+  for (const path of group.files) assert.equal(assets.groups.core.files.includes(path), false, `${path} is not core`);
+  const sw = readFileSync(join(root, 'sw.js'), 'utf8');
+  for (const path of group.files) assert.equal(sw.includes(`'${path}'`), false, `${path} is not in the legacy shell`);
+});
+
+test('JamesDSP resolves every module dependency through the page build manifest', () => {
+  const node = readFileSync(join(root, 'vendor/jamesdsp/jamesdsp-node.mjs'), 'utf8');
+  const worklet = readFileSync(join(root, 'vendor/jamesdsp/worklet.mjs'), 'utf8');
+  assert.match(node, /globalThis\.Lazy\?\.url\?\.\(path\)/);
+  assert.match(node, /assetURL\('\/vendor\/jamesdsp\/dsp\/jamesdsp\.wasm'/);
+  assert.match(node, /assetURL\('\/vendor\/jamesdsp\/params\.mjs'/);
+  assert.match(node, /processorOptions:\{wasmBytes\}/);
+  assert.match(worklet, /import createJamesDSP from '\.\/dsp\/jamesdsp-a982b53\.mjs'/);
+  assert.doesNotMatch(worklet, /import\(/);
+  assert.match(node, /context\.sampleRate<8000\|\|context\.sampleRate>96000/);
+  assert.match(node, /!\[1,2,4\]\.includes\(buffer\.numberOfChannels\) \|\| buffer\.length>65536/);
+  const feature = readFileSync(join(root, 'vendor/jamesdsp/jamesdsp-feature.js'), 'utf8');
+  assert.match(feature, /Lazy\.url\('\/vendor\/jamesdsp\/jamesdsp-node\.mjs'\)/);
+  assert.match(feature, /Lazy\.url\('\/vendor\/jamesdsp\/dsp\/jamesdsp\.wasm'\)/);
+});
+
+test('player wrapper rejects text effects while portable presets retain IR references', () => {
+  const node = readFileSync(join(root, 'vendor/jamesdsp/jamesdsp-node.mjs'), 'utf8');
+  const worklet = readFileSync(join(root, 'vendor/jamesdsp/worklet.mjs'), 'utf8');
+  assert.match(node, /Text effects are disabled in this player version/);
+  assert.match(node, /toJSON\(\) \{return \{version:2,params:/);
+  assert.match(node, /irCapFrames:view\.getUint32\(32,true\)/);
+  assert.match(node, /getIR\(preset\.irRef\.name\)/);
+  const feature = readFileSync(join(root, 'vendor/jamesdsp/jamesdsp-feature.js'), 'utf8');
+  assert.match(feature, /async function prepareIR\(context, buffer, maxFrames = 65536\)/);
+  assert.match(feature, /prepared\.length>Math\.min\(65536,maxFrames\)/);
+  assert.doesNotMatch(worklet, /data\.type==='text'/);
+});
+
+test('vendor provenance pins the source and retains both supplied license texts', () => {
+  const version = readFileSync(join(root, 'vendor/jamesdsp/VERSION.txt'), 'utf8');
+  assert.match(version, /a982b53c4ab347d1d9c50f4ce7ee3c2735eaa817/);
+  assert.match(version, /GPL-2\.0 text/);
+  assert.ok(readFileSync(join(root, 'vendor/jamesdsp/LICENSE.txt'), 'utf8').includes('Version 3'));
+  assert.ok(readFileSync(join(root, 'vendor/jamesdsp/UPSTREAM-MAIN-LICENSE.txt'), 'utf8').includes('Version 2'));
+});
--- a/frontend/jamesdsp-controller.test.js
+++ b/frontend/jamesdsp-controller.test.js
@@ -0,0 +1,114 @@
+const { test } = require('node:test');
+const assert = require('node:assert/strict');
+const { createController } = require('./vendor/jamesdsp/jamesdsp-feature.js');
+
+function fixture({ loadNode } = {}) {
+  const routed = [], errors = [], created = [], configured = [], bypass = [];
+  const graph = { routeAll: (elements, destination) => routed.push([elements.map(x => x.id), destination]) };
+  const gainParam = { value: 1, cancelScheduledValues() {}, setValueAtTime(v) { this.value = v; }, linearRampToValueAtTime(v) { this.value = v; } };
+  const context = { sampleRate: 48000, state: 'running', currentTime: 0, destination: 'destination', createGain: () => ({ gain: gainParam, connect() {}, disconnect() {} }), resume: async () => {} };
+  const standardInput = 'standard-input', elements = [{ id: 'video' }, { id: 'audio' }];
+  const prepareGraph = async () => ({ context, standardInput, elements });
+  const defaultLoad = async () => {
+    const listeners = new Map();
+    const instance = {
+      node: { connect() {}, disconnect() {} }, destroyed: false,
+      addEventListener(type, fn) { listeners.set(type, fn); },
+      removeEventListener(type, fn) { if (listeners.get(type) === fn) listeners.delete(type); },
+      async setBypass(v) { bypass.push(v); },
+      async applyPreset(params) { configured.push({ ...params }); },
+      async setParam(name, value) { configured.push({ [name]: value }); },
+      destroy() { this.destroyed = true; },
+      fail(error) { listeners.get('error')?.({ detail: error }); },
+    };
+    created.push(instance); return instance;
+  };
+  const controller = createController({ graph, prepareGraph, loadNode: loadNode || defaultLoad, onError: error => errors.push(error) });
+  return { controller, routed, errors, created, configured, bypass, context, elements, standardInput };
+}
+
+test('enable routes one initialized JamesDSP node and disable restores Standard before destroying it', async () => {
+  const f = fixture();
+  assert.equal(await f.controller.enable({ preset: 'bass', params: { gain: -2 } }, 3), true);
+  assert.equal(f.controller.active, true);
+  assert.deepEqual(f.routed, [[['video', 'audio'], f.created[0].node]]);
+  assert.equal(f.created.length, 1);
+  assert.equal(f.controller.state().liveHeaps, 1);
+  assert.equal(f.controller.state().maxLiveHeaps, 1);
+  const standard = f.controller.disable();
+  assert.deepEqual(f.routed.at(-1), [['video', 'audio'], f.standardInput]);
+  await standard;
+  assert.equal(f.created[0].destroyed, true);
+  assert.equal(f.controller.state().liveHeaps, 0);
+  assert.equal(f.controller.state().nodesDestroyed, 1);
+  assert.equal(f.errors.length, 0);
+});
+
+test('a rejected or unsupported engine leaves the Standard route active', async () => {
+  const f = fixture({ loadNode: async () => { throw new Error('corrupt wasm'); } });
+  await assert.rejects(f.controller.enable({ preset: 'flat' }), /corrupt wasm/);
+  assert.deepEqual(f.routed, [[['video', 'audio'], f.standardInput]]);
+  assert.equal(f.controller.active, false);
+  assert.equal(f.controller.state().liveHeaps, 0);
+  assert.equal(f.errors.length, 1);
+
+  const supportedRate = fixture();
+  supportedRate.context.sampleRate = 32000;
+  await supportedRate.controller.enable({ preset: 'flat' });
+  assert.equal(supportedRate.controller.state().active, true);
+  assert.equal(supportedRate.controller.state().sampleRate, 32000);
+});
+
+test('a runtime worklet failure switches sources to Standard before destroying the heap', async () => {
+  const f = fixture();
+  await f.controller.enable({ preset: 'flat' });
+  const instance = f.created[0];
+  instance.fail(new Error('processor fault'));
+  assert.deepEqual(f.routed.at(-1), [['video', 'audio'], f.standardInput]);
+  assert.equal(instance.destroyed, true);
+  assert.equal(f.controller.active, false);
+  assert.equal(f.controller.state().liveHeaps, 0);
+  assert.match(f.errors[0].message, /processor fault/);
+});
+
+test('disable during async node loading prevents a late DSP route', async () => {
+  let finish;
+  const f = fixture({ loadNode: () => new Promise(resolve => { finish = resolve; }) });
+  const enabling = f.controller.enable({ preset: 'flat' });
+  await new Promise(resolve => setImmediate(resolve));
+  const disabling = f.controller.disable();
+  const neverRouted = {
+    node: { connect() {}, disconnect() {} },
+    addEventListener() {}, removeEventListener() {}, setBypass: async () => {}, applyPreset: async () => {}, setParam: async () => {}, destroy() { this.destroyed = true; },
+  };
+  finish(neverRouted);
+  await enabling; await disabling;
+  assert.equal(f.routed.some(([, destination]) => destination === neverRouted.node), false);
+  assert.equal(neverRouted.destroyed, true);
+  assert.equal(f.controller.state().maxLiveHeaps, 0);
+});
+
+test('preset gain and Level gain combine within engine bounds without pausing playback', async () => {
+  const f = fixture();
+  await f.controller.enable({ preset: 'loudness', params: { gain: 8 } }, 9);
+  assert.ok(f.configured.some(entry => entry.gain === 12));
+  assert.equal(f.created.length, 1);
+  assert.equal(f.controller.state().maxLiveHeaps, 1);
+  assert.equal(f.controller.active, true);
+});
+
+test('A/B bypass is retained when settings are reapplied', async () => {
+  const f = fixture();
+  await f.controller.enable({ preset: 'warm' }, 0);
+  assert.equal(await f.controller.toggleBypass(), true);
+  assert.equal(f.controller.state().route, 'standard');
+  assert.deepEqual(f.routed.at(-1), [['video', 'audio'], f.standardInput], 'bypass follows the exact Standard route');
+  await f.controller.enable({ preset: 'bass' }, 0);
+  assert.equal(f.controller.state().bypassed, true);
+  assert.equal(f.controller.state().route, 'standard');
+  assert.deepEqual(f.routed.at(-1), [['video', 'audio'], f.standardInput], 'settings changes cannot replace the Standard route while bypassed');
+  assert.ok(f.bypass.at(-1));
+  assert.equal(await f.controller.toggleBypass(), false);
+  assert.equal(f.controller.state().route, 'jamesdsp');
+  assert.equal(f.bypass.at(-1), false);
+});
--- a/frontend/jamesdsp-ir.test.js
+++ b/frontend/jamesdsp-ir.test.js
@@ -0,0 +1,23 @@
+const { test } = require('node:test');
+const assert = require('node:assert/strict');
+
+test('generated room responses support four true-stereo paths and respect the low-memory cap', async () => {
+  const { generateIR, BUILTIN_IRS } = await import('./vendor/jamesdsp/ir-builtins.mjs');
+  const { resampleIR } = await import('./vendor/jamesdsp/ir-utils.mjs');
+  const ir = generateIR('Hall', 48000, 4, { maxFrames: 24000 });
+  assert.equal(ir.numberOfChannels, 4);
+  assert.equal(ir.length, 24000);
+  assert.equal(ir.truncated, true);
+  assert.ok(ir.getChannelData(0).some((sample, i) => sample !== ir.getChannelData(1)[i]), 'each matrix path has distinct taps');
+  const converted = resampleIR(ir, 32000);
+  assert.equal(converted.sampleRate, 32000);
+  assert.equal(converted.numberOfChannels, 4);
+  assert.equal(converted.length, 16000);
+  assert.deepEqual(Object.keys(BUILTIN_IRS), ['Small room', 'Hall', 'Plate', 'Cathedral']);
+});
+
+test('the IndexedDB store rejects impulse responses beyond its measured internal-frame cap', async () => {
+  const { saveIR } = await import('./vendor/jamesdsp/ir-store.mjs');
+  const oversized = { sampleRate: 48000, numberOfChannels: 4, length: 65537, getChannelData: () => new Float32Array(65537) };
+  await assert.rejects(saveIR('oversized', oversized), /65,536-frame internal limit/);
+});
--- a/frontend/lazy.js
+++ b/frontend/lazy.js
@@ -6,6 +6,7 @@
  try { manifest = JSON.parse(doc.getElementById('ytp-assets').textContent); }
  catch { return; } // The index must supply this map; never fetch one during boot.
  const assets = new Map(), groups = new Map(), hooks = new Map();
+  let warmScheduled = false;
  const css = new Set([...doc.querySelectorAll('link[data-lazy-css]')].map(link => link.dataset.lazyCss));
  const selected = new Map();
  const url = path => selected.get(path) || (manifest.files[path]?.h ? path + '?v=' + manifest.files[path].h : './' + path.replace(/^\//,''));
@@ -50,14 +51,18 @@
    const style = /\.css$/.test(path);
    if (style && css.has(path)) return Promise.resolve();
    if (!style && !/\.js$/.test(path)) return Promise.resolve(); // workers/imports/fonts are not page scripts
-    const task = new Promise((resolve, reject) => {
+    const loadOnce = () => new Promise((resolve, reject) => {
      const node = doc.createElement(style ? 'link' : 'script');
+      const timer = setTimeout(() => { node.remove?.(); reject(new Error('Timed out loading ' + path)); }, 20000);
      if (style) { node.rel = 'stylesheet'; node.href = url(path); }
      else { node.async = false; node.src = url(path); }
-      node.onload = resolve;
-      node.onerror = () => reject(new Error('Unable to load ' + path));
+      node.onload = () => { clearTimeout(timer); resolve(); };
+      node.onerror = () => { clearTimeout(timer); node.remove?.(); reject(new Error('Unable to load ' + path)); };
      doc.head.append(node);
    });
+    const task = root.AsyncGuard?.retry
+      ? root.AsyncGuard.retry(loadOnce, { attempts: 3 })
+      : loadOnce();
    assets.set(path, task);
    task.catch(() => assets.delete(path));
    return task;
@@ -100,10 +105,17 @@
      else root.navigator.serviceWorker?.getRegistration().then(send).catch(()=>{});
    },
    warm() {
-      if (!root.navigator.serviceWorker || root.navigator.onLine === false) return;
+      if (warmScheduled || !root.navigator.serviceWorker || root.navigator.onLine === false) return;
+      warmScheduled = true;
+      const start = () => {
+        warmScheduled = false;
+        if(root.navigator.onLine === false)return;
        root.navigator.serviceWorker.ready.then(reg => {
          for (const worker of new Set([reg.active, reg.waiting])) worker?.postMessage({type:'COMPLETE_ASSETS'});
        }).catch(()=>{});
+      };
+      if (root.requestIdleCallback) root.requestIdleCallback(start, { timeout: 8000 });
+      else setTimeout(start, 5000);
    },
    onLoad(name, fn) {
      if(api.loaded(name)) { Promise.resolve().then(fn).catch(error=>{if(root.CustomEvent)root.dispatchEvent?.(new root.CustomEvent('ytp-lazy-error',{detail:{group:name,error}}));}); return; }
--- a/frontend/lazy.test.js
+++ b/frontend/lazy.test.js
@@ -7,7 +7,7 @@ function fixture(current, held = [], appCache = false, userAgent = 'AppleWebKit/
  const manifest = { buildTag: 'own', appCache, groups: { core: { files: [] }, 'layout:classic': { files: ['/classic.css'] }, 'layout:glass-stage': { files: ['/glass.css', '/one.js', '/two.js'] }, 'feature:test': { contract:1, files: ['/one.js', '/two.js'] } }, files: { '/app.js':{h:'a'}, '/classic.css': {h:'c'}, '/glass.css':{h:'g'}, '/one.js':{h:'1'}, '/two.js':{h:'2'} } };
  const doc = { readyState:'loading', documentElement: { dataset:{} }, getElementById: () => ({ textContent:JSON.stringify(manifest) }), querySelectorAll: () => [], createElement: tag => ({ tagName:tag.toUpperCase() }), write: value => writes.push(value), addEventListener: (t,f) => listeners[t]=f };
  doc.head = { append: node => { inserted.push(node); queueMicrotask(() => node.onload?.()); } };
-  const root = { document:doc, localStorage:{ getItem:() => '{"settings":{"layout":"glass-stage"}}' }, console, Promise, URL, crypto:{subtle:{}}, fetch:async key=>{fetched.push(key);return new Response('app');}, setTimeout, clearTimeout, navigator:{userAgent,serviceWorker:{ready:Promise.resolve({}),controller:controlled?{}:null,addEventListener(){}}}, addEventListener(){} };
+  const root = { document:doc, localStorage:{ getItem:() => '{"settings":{"layout":"glass-stage"}}' }, console, Promise, URL, crypto:{subtle:{}}, AsyncGuard:require('./async-guard'), requestIdleCallback:fn=>{root.__idle=fn;}, fetch:async key=>{fetched.push(key);return new Response('app');}, setTimeout, clearTimeout, navigator:{userAgent,serviceWorker:{ready:Promise.resolve({}),controller:controlled?{}:null,addEventListener(){}}}, addEventListener(){} };
  if (current) root.caches = { open: async () => ({ match: async key => key === '/__ytp_asset_state' ? new Response(JSON.stringify({current})) : held.includes(key) ? new Response('', {headers:{'X-Asset-Hash':key.split('=')[1]}}) : undefined }) };
  root.window=root; root.globalThis=root;
  vm.runInNewContext(readFileSync(require.resolve('./lazy.js'),'utf8'), root);
@@ -27,11 +27,13 @@ test('lazy groups execute ordered classic scripts once, sharing concurrent calls
  await root.Lazy.load('layout:glass-stage');
  assert.equal(inserted.filter(n=>n.tagName==='SCRIPT').length,2);
 });
-test('failed injection can retry and proxy dispatches only after execution', async () => {
+test('transient script injection failure retries before proxy dispatch', async () => {
  const {root,inserted}=fixture();
  const append=root.document.head.append;
-  root.document.head.append=n=>{inserted.push(n);queueMicrotask(()=>n.onerror?.());};
-  await assert.rejects(root.Lazy.load('feature:test'),/one.js/);
+  let first=true;
+  root.document.head.append=n=>{inserted.push(n);queueMicrotask(()=>{if(first){first=false;n.onerror?.();}else n.onload?.();});};
+  await root.Lazy.load('feature:test');
+  assert.equal(inserted.length,3,'first file is retried, then the second file loads');
  root.document.head.append=append;
  root.TestApi={open:value=>value+1};
  const proxy=root.Lazy.proxy('feature:test',['open'],'TestApi');
@@ -92,6 +94,8 @@ test('online launches request worker completion even with Save-Data and skip off
 f.root.navigator.connection={saveData:true};f.root.navigator.onLine=true;
 f.root.navigator.serviceWorker={ready:Promise.resolve({active,waiting})};
 f.root.Lazy.warm();await Promise.resolve();
+ assert.equal(sent.length,0,'warming waits until the page is idle');
+ f.root.__idle();await Promise.resolve();
 assert.deepEqual(sent.map(m=>m.type),['COMPLETE_ASSETS','COMPLETE_ASSETS']);
 f.root.navigator.onLine=false;f.root.Lazy.warm();await Promise.resolve();assert.equal(sent.length,2);
 });
--- a/frontend/settings-persist.test.js
+++ b/frontend/settings-persist.test.js
@@ -6,9 +6,10 @@ const source = fs.readFileSync(__dirname + '/app.js', 'utf8');
 // Exercise the production persistence/profile functions without starting a DOM player.
 const declaration = name => source.match(new RegExp('(?:async )?function ' + name + '\\([^]*?\\n}'))[0];
 function fixture(updatedAt) {
-  const settings = { saveBeforePlay: true, autoPreload: true, layout: 'f7-swipe', eq: { preset: 'custom', g: [1,2,3,4,5] } };
-  const context = vm.createContext({ WEB: true, data: { settings, profile: { name: 'test', syncedAt: 200 } }, DEFAULT_SETTINGS: { saveBeforePlay: false, autoPreload: true, layout: 'classic' }, API: { saveData: async () => {} }, profileHeaders: () => ({}), scheduleProfilePush: () => context.pushes++, pushes: 0, fetch: async () => ({ status: 200, json: async () => ({ ok: true, name: 'test', updatedAt, data: { settings: { saveBeforePlay: false } } }) }), localStorage: { getItem: () => JSON.stringify({ settings }) } });
-  vm.runInContext([declaration('loadDataFromStorage'), declaration('applyProfileData'), declaration('pullProfileIfNewer')].join('\n'), context);
+  const settings = { saveBeforePlay: true, autoPreload: true, layout: 'f7-swipe', eq: { preset: 'custom', g: [1,2,3,4,5] }, jamesDsp: { enabled: true, downloadForOffline: true, preset: 'warm', params: { 'eq.band0': 3 } } };
+  const defaults = { saveBeforePlay: false, autoPreload: true, layout: 'classic', jamesDsp: { enabled: false, downloadForOffline: false, preset: 'flat', params: {} } };
+  const context = vm.createContext({ WEB: true, data: { settings, profile: { name: 'test', syncedAt: 200 } }, DEFAULT_SETTINGS: defaults, API: { saveData: async () => {} }, profileHeaders: () => ({}), scheduleProfilePush: () => context.pushes++, pushes: 0, fetch: async () => ({ status: 200, json: async () => ({ ok: true, name: 'test', updatedAt, data: { settings: { saveBeforePlay: false } } }) }), localStorage: { getItem: () => JSON.stringify({ settings }) } });
+  vm.runInContext([declaration('loadDataFromStorage'), declaration('normalizeJamesDspSettings'), declaration('applyProfileData'), declaration('pullProfileIfNewer')].join('\n'), context);
  return context;
 }
 test('stored settings load verbatim instead of reverting to defaults', () => {
@@ -17,6 +18,7 @@ test('stored settings load verbatim instead of reverting to defaults', () => {
  assert.equal(loaded.settings.saveBeforePlay, true);
  assert.equal(loaded.settings.layout, 'f7-swipe');
  assert.deepEqual(JSON.parse(JSON.stringify(loaded.settings.eq.g)), [1,2,3,4,5]);
+  assert.deepEqual(JSON.parse(JSON.stringify(loaded.settings.jamesDsp)), { enabled: true, downloadForOffline: true, preset: 'warm', params: { 'eq.band0': 3 } });
 });
 for (const updatedAt of [100,200]) test(`profile timestamp ${updatedAt} cannot overwrite local settings synced at 200`, async () => {
  const c = fixture(updatedAt), previous = c.data.settings;
@@ -30,5 +32,6 @@ test('newer profile intentionally replaces settings and restores missing default
  assert.equal(c.data.settings.saveBeforePlay, false);
  assert.equal(c.data.settings.autoPreload, true);
  assert.equal(c.data.settings.layout, 'classic');
+  assert.deepEqual(JSON.parse(JSON.stringify(c.data.settings.jamesDsp)), { enabled: false, downloadForOffline: false, preset: 'flat', params: {}, irRef: null });
  assert.equal(c.data.profile.syncedAt, 300);
 });
--- a/frontend/settings-sections.css
+++ b/frontend/settings-sections.css
@@ -1,4 +1,27 @@
 .settings-browser { display: block; width: 100%; min-width: 0; }
+.settings-browser, .settings-grid, .settings-overview, .settings-detail, .settings-section,
+.settings-browser .settings, .settings-browser .set-group, .settings-browser .dsp-settings,
+.settings-browser .dsp-subsection, .settings-browser .dsp-param-list {
+  box-sizing: border-box;
+  min-width: 0;
+  max-width: 100%;
+}
+/* Settings is a workspace, not a sidebar: give the section browser the full
+   content area on desktop instead of leaving it inside the fixed 452px list. */
+.body:has(#listPane .cards[data-view="settings"]) .player-pane { display: none; }
+.body:has(#listPane .cards[data-view="settings"]) #listPane {
+  flex: 1 1 0;
+  width: 100%;
+  min-width: 0;
+  max-width: 100%;
+  border-left: 0;
+}
+.body:has(#listPane .cards[data-view="settings"]) #listPane .cards {
+  width: 100%;
+  min-width: 0;
+  max-width: 100%;
+  overflow-x: hidden;
+}
 .settings-browser [hidden] { display: none !important; }
 .settings-search { margin-bottom: 12px; }
 .settings-search input { width: 100%; min-height: 44px; background: var(--bg-2); color: var(--text); border: 1px solid var(--line); border-radius: 8px; padding: 10px 12px; font: inherit; }
@@ -11,10 +34,81 @@
 .settings-section-row:hover, .settings-section-row[aria-current="true"] { background: var(--bg-3); border-radius: 8px; }
 .settings-browser :is(button,input,select,textarea):focus-visible { outline: 2px solid var(--accent); outline-offset: 3px; }
 .settings-back { min-height: 44px; padding: 8px 12px; margin-bottom: 12px; background: var(--bg-2); color: var(--text); border: 1px solid var(--line); border-radius: 8px; font: inherit; cursor: pointer; }
-.settings-browser .set-row { min-height: 44px; }
+.settings-browser .set-row {
+  display: grid;
+  grid-template-columns: minmax(0, 1fr) minmax(0, min(40%, 260px));
+  align-items: center;
+  gap: 12px;
+  min-height: 44px;
+  min-width: 0;
+  max-width: 100%;
+}
+.settings-browser .set-row > :is(span, input, select, button, output) { min-width: 0; max-width: 100%; }
+.settings-browser .set-row > :is(input, select, button, output) { box-sizing: border-box; }
+.settings-browser .set-control-wrap { display: block; width: 100%; min-width: 0; max-width: 100%; overflow: hidden; }
+#listPane #cards .settings-browser .set-row select,
+#listPane #cards .settings-browser .set-control-wrap select,
+.settings-browser .set-row select,
+.settings-browser .set-control-wrap select {
+  box-sizing: border-box;
+  appearance: none;
+  -webkit-appearance: none;
+  width: 100%;
+  min-width: 0;
+  max-width: 100%;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  padding-right: 28px;
+  background-color: var(--bg-3);
+  background-image: linear-gradient(45deg, transparent 50%, var(--text-dim) 50%), linear-gradient(135deg, var(--text-dim) 50%, transparent 50%);
+  background-position: calc(100% - 14px) 50%, calc(100% - 9px) 50%;
+  background-size: 5px 5px;
+  background-repeat: no-repeat;
+  color: var(--text);
+  border-color: var(--line);
+}
+.settings-browser .set-row > span:first-child { overflow-wrap: anywhere; }
+.settings-browser .set-row:has(> span:only-child) { grid-template-columns: minmax(0, 1fr); }
 .settings-browser .set-row small { font-size: 12px; max-width: 100%; }
 .settings-browser .set-row > span { min-width: 0; }
-.settings-browser .set-row input[type="range"] { max-width: 42%; }
+.settings-browser .set-row input[type="range"] { width: calc(100% - 16px); max-width: calc(100% - 16px); min-width: 0; }
+.settings-browser .set-row input[type="checkbox"] {
+  appearance: none;
+  -webkit-appearance: none;
+  justify-self: end;
+  width: 46px;
+  height: 28px;
+  min-width: 46px;
+  border: 1px solid var(--line);
+  border-radius: 999px;
+  background: radial-gradient(circle at 14px 50%, var(--text) 0 9px, transparent 10px), var(--bg-3);
+  cursor: pointer;
+  transition: background .16s ease, border-color .16s ease;
+}
+.settings-browser .set-row input[type="checkbox"]:checked {
+  border-color: var(--accent);
+  background: radial-gradient(circle at 32px 50%, var(--on-accent, #fff) 0 9px, transparent 10px), var(--accent);
+}
+.settings-browser .set-row input[type="checkbox"]:focus-visible { outline: 2px solid var(--accent); outline-offset: 3px; }
+.dsp-file-control {
+  position: relative;
+  display: grid;
+  grid-template-columns: max-content minmax(0, 1fr);
+  align-items: center;
+  gap: 9px;
+  width: 100%;
+  min-width: 0;
+  max-width: 100%;
+}
+.dsp-file-control input[type="file"] { position: absolute; width: 1px; height: 1px; min-width: 0; max-width: 1px; padding: 0; border: 0; overflow: hidden; clip-path: inset(50%); white-space: nowrap; }
+.dsp-file-control:focus-within { outline: 2px solid var(--accent); outline-offset: 3px; border-radius: 8px; }
+.dsp-file-button { display: inline-flex; align-items: center; justify-content: center; min-height: 40px; padding: 7px 12px; border: 1px solid var(--line); border-radius: 9px; background: var(--bg-3); color: var(--text); font: 600 12px var(--ui); white-space: nowrap; }
+.dsp-file-name { display: block; min-width: 0; overflow: hidden; color: var(--text-2); text-overflow: ellipsis; white-space: nowrap; font-size: 12px; }
+.dsp-subsection .sp-note { min-width: 0; max-width: 100%; overflow-wrap: anywhere; }
+.dsp-subsection > .btn { min-width: 0; max-width: 100%; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
+.dsp-actions { min-width: 0; max-width: 100%; }
+.dsp-param-list { grid-template-columns: repeat(auto-fit, minmax(min(190px, 100%), 1fr)); }
+.dsp-param-row input[type="range"] { width: calc(100% - 16px); min-width: 0; max-width: calc(100% - 16px); }
 .settings-browser .settings-detail { display: none; min-width: 0; }
 .settings-browser[data-detail="1"] .settings-overview { display: none; }
 .settings-browser[data-detail="1"] .settings-detail { display: block; }
@@ -22,7 +116,7 @@
  .settings-grid { display: grid; grid-template-columns: minmax(160px, .8fr) minmax(0, 1.4fr); gap: 16px; }
  .settings-browser .settings-overview, .settings-browser[data-detail="1"] .settings-overview, .settings-browser .settings-detail { display: block; }
  .settings-back { display: none; }
-  .settings-browser .set-row { flex-wrap: wrap; gap: 12px; }
+  .settings-browser .set-row { flex-wrap: nowrap; gap: 12px; }
 }
 .download-job { padding: 14px 0; border-bottom: 1px solid var(--line); display: grid; gap: 8px; }
 .download-job b { overflow-wrap: anywhere; }
--- a/frontend/shell-consistency.test.js
+++ b/frontend/shell-consistency.test.js
@@ -42,7 +42,9 @@ test('assets.json describes the complete existing shell exactly once with eager
  }
  for (const asset of shell) if (asset !== '/') assert.ok(described.has(asset), `${asset} is described`);
  // piano-engine is dynamically imported and historically absent from SHELL.
-  for (const asset of described) assert.ok(listed.has(asset) || asset === '/piano-engine.mjs', `${asset} shell or documented dynamic import`);
+  // Piano and JamesDSP load only through build-local dynamic module URLs.
+  const dynamicOnly = new Set(['/piano-engine.mjs', ...groups['feature:jamesdsp'].files]);
+  for (const asset of described) assert.ok(listed.has(asset) || dynamicOnly.has(asset), `${asset} shell or documented dynamic import`);
  assert.equal(groups.core.eager, true);
  for (const name of ['playlist', 'settings', 'service-mode', 'lyrics-editor']) {
    assert.equal(groups[`feature:${name}`].eager, true);
--- a/frontend/styles.css
+++ b/frontend/styles.css
@@ -1159,6 +1159,15 @@ input[type="range"]::-webkit-slider-thumb:hover { transform: scale(1.25); }
 .set-row > span { display: flex; flex-direction: column; gap: 3px; color: var(--text); font-size: 13.5px; font-weight: 500; }
 .set-row small { color: var(--text-dim); font-size: 11.5px; font-weight: 400; line-height: 1.4; max-width: 280px; }
 .set-row input[type="range"] { width: 150px; }
+.dsp-settings { margin-top: 8px; padding: 12px; border: 1px solid var(--line); border-radius: 12px; background: var(--bg-2); }
+.dsp-settings .set-group-title { padding: 0 0 8px; }
+.dsp-param-list { display: grid; grid-template-columns: repeat(auto-fit, minmax(190px, 1fr)); gap: 0 14px; }
+.dsp-param-row input[type="range"] { width: min(46vw, 190px); }
+.dsp-actions { display: flex; flex-wrap: wrap; gap: 8px; padding: 10px 0; }
+.dsp-actions .btn { color: var(--text); }
+.dsp-subsection { margin: 14px 0; padding: 12px; border: 1px solid var(--line); border-radius: 10px; background: var(--bg-1); }
+.dsp-subsection h4 { margin: 0 0 8px; color: var(--text); }
+.dsp-risk { padding: 9px 11px; border-radius: 8px; color: var(--text); background: color-mix(in srgb, var(--accent) 13%, var(--bg-2)); font-size: .9em; }
 .set-row input[type="checkbox"] { width: 17px; height: 17px; accent-color: var(--accent); cursor: pointer; }
 .about-version { color: var(--text-dim); font-size: 12px; font-family: ui-monospace, SFMono-Regular, Menlo, monospace; user-select: text; }
 .set-select {
--- a/frontend/sw.js
+++ b/frontend/sw.js
@@ -70,6 +70,7 @@ const SHELL = [
  '/glass-panel-layout.js',
  '/theme-classic.css',
  '/recommendations.css',
+  '/audio-graph.js',
  '/flag-ui.js',
  '/export.js',
  '/async-guard.js',
@@ -264,7 +265,8 @@ self.addEventListener('fetch', (e) => {
    return;
  }

-  if (ASSET_SYNC && request.mode === 'navigate') e.waitUntil(completeAssets());
+  // The page schedules completion after first paint/idle via Lazy.warm(). Do
+  // not start a six-file background burst from this foreground fetch event.

  // Only intercept GET/HEAD — let POST (sync endpoint) go through unmodified
  if (request.method !== 'GET' && request.method !== 'HEAD') return;
@@ -304,13 +306,18 @@ self.addEventListener('fetch', (e) => {
 const playingClients = new Map(), deferredClients = new Set();
 let activeLayout = 'classic', layoutReply;
 let completionTask;
-function completeAssets(force = false) {
+function completeAssets(force = false, requestedOptIns) {
  if (!ASSET_SYNC) return Promise.resolve();
+  if (completionTask) {
+    if (!requestedOptIns) return completionTask;
+    return completionTask.finally(() => completeAssets(true, requestedOptIns));
+  }
  completionTask ||= (async () => {
    const cache = await caches.open(AssetSyncCore.CACHE);
    const m = (await AssetSyncCore.state(cache))?.current;
    if (!m || m.buildTag !== VERSION) return;
-    const job = await AssetSyncCore.complete(m, { cache, fetchFn: fetch, force,
+    const optIns = requestedOptIns || await AssetSyncCore.readOptIns(cache);
+    const job = await AssetSyncCore.complete(m, { cache, fetchFn: fetch, force, optIns,
      notify: async status => {
        for (const client of await self.clients.matchAll({ type: 'window' }))
          client.postMessage({ type: 'OFFLINE_STATUS', ...status });
@@ -329,6 +336,16 @@ self.addEventListener('sync', e => {
  if (e.tag === 'ytp-offline-complete') e.waitUntil(completeAssets());
 });
 self.addEventListener('message', (e) => {
+  if (ASSET_SYNC && e.data?.type === 'OFFLINE_OPT_INS' && Array.isArray(e.data.values)) {
+    e.waitUntil((async () => {
+      const cache = await caches.open(AssetSyncCore.CACHE);
+      const current = (await AssetSyncCore.state(cache))?.current || await candidate(cache);
+      const allowed = new Set(Object.values(current?.groups || {}).map(group => group.offlineOptIn).filter(Boolean));
+      const values = [...new Set(e.data.values.filter(value => typeof value === 'string' && allowed.has(value)))];
+      await cache.put(AssetSyncCore.OPT_INS, Response.json(values));
+      await completeAssets(true, values);
+    })());
+  }
  if (ASSET_SYNC && e.data?.type === 'LAYOUT' && e.source && typeof e.data.value === 'string') {
    activeLayout = e.data.value;
    layoutReply?.();
@@ -535,6 +552,10 @@ async function installAssets() {
    for(const name of layouts)for(const dependency of m.groups[name].dependencies || [])layouts.add(dependency);
    await AssetSyncCore.syncAssets(m,{cache,fetchFn:fetchAsset,groups:[...layouts]});
  }
+  // Copy and hash legacy shell entries before the candidate reaches `installed`.
+  // A legacy page's Refresh UI then activates quickly, before its four-second
+  // reload safety timer can send it back into the old shell.
+  m.legacyCacheNames = await migrateLegacy(cache,m);
  await cache.put(candidateKey, new Response(JSON.stringify(m)));
 }
 async function migrateLegacy(cache, m) {
@@ -565,7 +586,11 @@ async function migrateLegacy(cache, m) {
 async function activateAssets() {
  const cache = await caches.open(AssetSyncCore.CACHE), m = await candidate(cache);
  if (!m) throw Error('Missing candidate manifest');
-  const names = await migrateLegacy(cache,m), old = await AssetSyncCore.state(cache);
+  // Legacy migration is staged by installAssets. Keep the fallback for
+  // candidates created by an older worker version.
+  const names = m.legacyCacheNames || await migrateLegacy(cache,m);
+  delete m.legacyCacheNames;
+  const old = await AssetSyncCore.state(cache);
  const previousClients = (await self.clients.matchAll({type:'window'})).map(c=>c.id);
  await AssetSyncCore.commit(m,cache,{previousClients,activeLayout:m.activeLayout || activeLayout});
  // Legacy deletion occurs strictly after verified commit.
@@ -573,8 +598,8 @@ async function activateAssets() {
  for (const req of await cache.keys()) if(new URL(req.url).pathname.startsWith('/__ytp_candidate/')) await cache.delete(req);
  await self.clients.claim();
  if(old && old.current.buildTag !== m.buildTag) for(const c of await self.clients.matchAll({type:'window',includeUncontrolled:true})) c.postMessage({type:'SW_UPDATE_AVAILABLE',version:VERSION});
-  // Completion owns a message-event lifetime, not the activation barrier.
-  // In particular, a legacy client's four-second reload must not wait for it.
+  // Resume completion after activation, but with one request at a time so
+  // foreground navigation retains most of the available bandwidth.
  self.registration.active.postMessage({ type: 'COMPLETE_ASSETS' });
  try { console.info('[asset-sync] storage', await self.navigator.storage.estimate()); } catch {}
 }
--- a/frontend/vendor/jamesdsp/LICENSE.txt
+++ b/frontend/vendor/jamesdsp/LICENSE.txt
@@ -0,0 +1,674 @@
+                    GNU GENERAL PUBLIC LICENSE
+                       Version 3, 29 June 2007
+
+ Copyright (C) 2007 Free Software Foundation, Inc. <https://fsf.org/>
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
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+combination as such.
+
+  14. Revised Versions of this License.
+
+  The Free Software Foundation may publish revised and/or new versions of
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+be similar in spirit to the present version, but may differ in detail to
+address new problems or concerns.
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+  Each version is given a distinguishing version number.  If the
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+GNU General Public License, you may choose any version ever published
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+  If the Program specifies that a proxy can decide which future
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+  Later license versions may give you additional or different
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+
+  17. Interpretation of Sections 15 and 16.
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+  If the disclaimer of warranty and limitation of liability provided
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+
+                     END OF TERMS AND CONDITIONS
+
+            How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+state the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
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+
+    This program is distributed in the hope that it will be useful,
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+    This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+    This is free software, and you are welcome to redistribute it
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+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License.  Of course, your program's commands
+might be different; for a GUI interface, you would use an "about box".
+
+  You should also get your employer (if you work as a programmer) or school,
+if any, to sign a "copyright disclaimer" for the program, if necessary.
+For more information on this, and how to apply and follow the GNU GPL, see
+<https://www.gnu.org/licenses/>.
+
+  The GNU General Public License does not permit incorporating your program
+into proprietary programs.  If your program is a subroutine library, you
+may consider it more useful to permit linking proprietary applications with
+the library.  If this is what you want to do, use the GNU Lesser General
+Public License instead of this License.  But first, please read
+<https://www.gnu.org/licenses/why-not-lgpl.html>.
--- a/frontend/vendor/jamesdsp/README.md
+++ b/frontend/vendor/jamesdsp/README.md
@@ -0,0 +1,17 @@
+# JamesDSP vendor files
+
+The browser port's worklet, 8–96 kHz streaming sample-rate adapter, matrix
+convolver, HRTF/virtual-speaker spatial stage, generated IRs and IndexedDB IR
+store are pinned to the source revision in VERSION.txt. Runtime files stay in
+the lazy `feature:jamesdsp` group. A user must enable the engine or choose
+“Download audio effects for offline” before the offline-completion job caches
+them, including the WASM binary.
+
+The adapted wrapper resolves dependencies through `Lazy.url()` and routes the
+worklet through the existing AudioGraph. It rejects Liveprog, DDC and arbitrary
+text effects. Impulse responses are limited to 65,536 internal frames; lower-
+power devices use a 24,000-frame cap and warn before larger responses are used.
+
+The port is GPL-3.0-or-later (`LICENSE.txt`). The upstream license snapshot says
+GPL-2.0; both supplied notices remain in this directory pending upstream
+clarification. See VERSION.txt for the adaptation record.
--- a/frontend/vendor/jamesdsp/UPSTREAM-MAIN-LICENSE.txt
+++ b/frontend/vendor/jamesdsp/UPSTREAM-MAIN-LICENSE.txt
@@ -0,0 +1,340 @@
+GNU GENERAL PUBLIC LICENSE
+                       Version 2, June 1991
+
+ Copyright (C) 1989, 1991 Free Software Foundation, Inc., <http://fsf.org/>
+ 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+                            Preamble
+
+  The licenses for most software are designed to take away your
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+Foundation's software and to any other program whose authors commit to
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+
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+
+                    GNU GENERAL PUBLIC LICENSE
+   TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
+
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+a notice placed by the copyright holder saying it may be distributed
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+
+                            NO WARRANTY
+
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+FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW.  EXCEPT WHEN
+OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
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+PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING,
+REPAIR OR CORRECTION.
+
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+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
+REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES,
+INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING
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+YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER
+PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGES.
+
+                     END OF TERMS AND CONDITIONS
+
+            How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+convey the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    {description}
+    Copyright (C) {year}  {fullname}
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License along
+    with this program; if not, write to the Free Software Foundation, Inc.,
+    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+Also add information on how to contact you by electronic and paper mail.
+
+If the program is interactive, make it output a short notice like this
+when it starts in an interactive mode:
+
+    Gnomovision version 69, Copyright (C) year name of author
+    Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+    This is free software, and you are welcome to redistribute it
+    under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License.  Of course, the commands you use may
+be called something other than `show w' and `show c'; they could even be
+mouse-clicks or menu items--whatever suits your program.
+
+You should also get your employer (if you work as a programmer) or your
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+
+  Yoyodyne, Inc., hereby disclaims all copyright interest in the program
+  `Gnomovision' (which makes passes at compilers) written by James Hacker.
+
+  {signature of Ty Coon}, 1 April 1989
+  Ty Coon, President of Vice
+
+This General Public License does not permit incorporating your program into
+proprietary programs.  If your program is a subroutine library, you may
+consider it more useful to permit linking proprietary applications with the
+library.  If this is what you want to do, use the GNU Lesser General
+Public License instead of this License.
+
--- a/frontend/vendor/jamesdsp/VERSION.txt
+++ b/frontend/vendor/jamesdsp/VERSION.txt
@@ -0,0 +1,18 @@
+JamesDSP browser port source revision: a982b53c4ab347d1d9c50f4ce7ee3c2735eaa817
+Repository: /home/josh/development/personal/jamesdsp-web (main)
+Vendored source files: web/jamesdsp-node.js, params.js, ir-utils.js,
+ir-builtins.js, ir-store.js, worklet.js, dsp/jamesdsp.js and dsp/jamesdsp.wasm.
+
+Integration adaptations: wrapper dependencies and WASM URLs use the page's
+manifest-hashed Lazy.url map; the worklet statically imports the pinned
+jamesdsp-a982b53.mjs module because AudioWorkletGlobalScope rejects dynamic
+import. The wrapper keeps the shared AudioGraph route and does not create a
+MediaElementSource. Liveprog, DDC and arbitrary text effects are rejected and
+not serialized in ytplayer. All runtime code remains in lazy feature:jamesdsp;
+its offline completion membership requires the explicit jamesDsp opt-in.
+
+The generated engine, parameter tables, IR utilities/store and built-in IR set
+are copied from the pinned revision. The uploaded/generated IR cap is 65,536
+frames at the internal 44.1/48 kHz rate (low-power devices use 24,000 frames).
+License provenance: LICENSE.txt is the port's GPL-3.0-or-later license. The
+upstream snapshot at upstream/Main/LICENSE contains GPL-2.0 text; see README.md.
--- a/frontend/vendor/jamesdsp/dsp/jamesdsp-a982b53.mjs
+++ b/frontend/vendor/jamesdsp/dsp/jamesdsp-a982b53.mjs
--- a/frontend/vendor/jamesdsp/dsp/jamesdsp.wasm
+++ b/frontend/vendor/jamesdsp/dsp/jamesdsp.wasm
--- a/frontend/vendor/jamesdsp/ir-builtins.mjs
+++ b/frontend/vendor/jamesdsp/ir-builtins.mjs
@@ -0,0 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+const definitions={
+  'Small room':{seconds:.5,rt60:.25,seed:0x51a11},
+  Hall:{seconds:2,rt60:1.4,seed:0x4a11},
+  Plate:{seconds:1.5,rt60:1,seed:0x91a7e},
+  Cathedral:{seconds:5,rt60:4,seed:0xca7ed},
+};
+export const BUILTIN_IRS=Object.freeze(Object.fromEntries(Object.entries(definitions).map(([name,d])=>[name,Object.freeze({...d,version:1})])));
+export function generateIR(name,sampleRate,channels=2,{maxFrames=65536}={}) {
+  const spec=BUILTIN_IRS[name];if(!spec||!Number.isInteger(sampleRate)||sampleRate<8000||sampleRate>96000||![1,2,4].includes(channels)) throw new RangeError('Unsupported generated IR');
+  const frames=Math.max(1,Math.min(Math.round(spec.seconds*sampleRate),maxFrames));let seed=spec.seed>>>0;
+  const paths=Array.from({length:channels},()=>new Float32Array(frames));
+  const next=()=>{seed=(Math.imul(seed,1664525)+1013904223)>>>0;return seed/0x100000000*2-1;};
+  for(let path=0;path<channels;path++) {
+    const x=paths[path];x[0]=1;
+    for(let tap=1;tap<Math.min(24,frames);tap++) {const at=Math.min(frames-1,Math.round(sampleRate*(.004+tap*.009+next()*.001)));x[at]+=(next()*.22)/(1+tap*.25);}
+    for(let i=1;i<frames;i++) {const t=i/sampleRate, fade=Math.min(1,t/.012,(frames-i)/Math.max(1,sampleRate*.02));x[i]+=next()*.045*Math.exp(-6.91*t/spec.rt60)*Math.max(0,fade);}
+  }
+  let peak=0;for(const path of paths) for(const value of path) peak=Math.max(peak,Math.abs(value));
+  for(const path of paths) for(let i=0;i<path.length;i++) path[i]*=.5/peak;
+  return {name,sampleRate,numberOfChannels:channels,length:frames,seed:spec.seed,version:1,truncated:frames<spec.seconds*sampleRate,getChannelData:i=>paths[i]};
+}
--- a/frontend/vendor/jamesdsp/ir-store.mjs
+++ b/frontend/vendor/jamesdsp/ir-store.mjs
@@ -0,0 +1,24 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+const DB='jamesdsp-ir', STORE='irs', VERSION=1;
+function openDB() {
+  if(!globalThis.indexedDB) return Promise.reject(new Error('IndexedDB is unavailable'));
+  return new Promise((resolve,reject)=>{const request=indexedDB.open(DB,VERSION);request.onupgradeneeded=()=>request.result.createObjectStore(STORE,{keyPath:'name'});request.onsuccess=()=>resolve(request.result);request.onerror=()=>reject(request.error);});
+}
+async function transaction(mode,action) {
+  const db=await openDB();return new Promise((resolve,reject)=>{const tx=db.transaction(STORE,mode),store=tx.objectStore(STORE);let result;try {result=action(store);} catch(error){db.close();reject(error);return;}tx.oncomplete=()=>{db.close();resolve(result);};tx.onerror=()=>{db.close();reject(tx.error);};tx.onabort=()=>{db.close();reject(tx.error||new Error('IR storage transaction aborted'));};});
+}
+async function digest(data) {const hash=await crypto.subtle.digest('SHA-256',data);return [...new Uint8Array(hash)].map(x=>x.toString(16).padStart(2,'0')).join('');}
+export async function saveIR(name,buffer,metadata={}) {
+  if(typeof name!=='string'||!name.trim()||name.length>100||![1,2,4].includes(buffer?.numberOfChannels)||!Number.isFinite(buffer.sampleRate)||buffer.sampleRate<8000||buffer.sampleRate>96000||!buffer.length) throw new TypeError('Invalid named impulse response');
+  const internalRate=buffer.sampleRate===44100?44100:48000;
+  if(Math.round(buffer.length*internalRate/buffer.sampleRate)>65536) throw new RangeError('Stored impulse response exceeds the 65,536-frame internal limit');
+  const channels=Array.from({length:buffer.numberOfChannels},(_,i)=>new Float32Array(buffer.getChannelData(i)));
+  const pcm=new Float32Array(channels.length*buffer.length);for(let i=0;i<buffer.length;i++)for(let c=0;c<channels.length;c++)pcm[i*channels.length+c]=channels[c][i];
+  const record={name:name.trim(),sampleRate:buffer.sampleRate,channels:channels.length,frames:buffer.length,pcm,metadata:{...metadata},hash:await digest(pcm.buffer),version:1};
+  await transaction('readwrite',s=>s.put(record));return {name:record.name,hash:record.hash};
+}
+export async function getIR(name) {
+  const db=await openDB();return new Promise((resolve,reject)=>{const r=db.transaction(STORE,'readonly').objectStore(STORE).get(name);r.onsuccess=async()=>{try {const x=r.result;if(!x){resolve(null);return;}if(await digest(x.pcm.buffer)!==x.hash)throw new Error('Stored IR hash mismatch');const channels=Array.from({length:x.channels},()=>new Float32Array(x.frames));for(let i=0;i<x.frames;i++)for(let c=0;c<x.channels;c++)channels[c][i]=x.pcm[i*x.channels+c];resolve({...x,buffer:{sampleRate:x.sampleRate,numberOfChannels:x.channels,length:x.frames,getChannelData:i=>channels[i]}});}catch(e){reject(e);}finally{db.close();}};r.onerror=()=>{db.close();reject(r.error);};});
+}
+export async function listIRs() {const db=await openDB();return new Promise((resolve,reject)=>{const r=db.transaction(STORE,'readonly').objectStore(STORE).getAll();r.onsuccess=()=>{db.close();resolve(r.result.map(({name,hash,sampleRate,channels,frames,metadata})=>({name,hash,sampleRate,channels,frames,metadata})));};r.onerror=()=>{db.close();reject(r.error);};});}
+export async function deleteIR(name) {await transaction('readwrite',s=>s.delete(name));}
--- a/frontend/vendor/jamesdsp/ir-utils.mjs
+++ b/frontend/vendor/jamesdsp/ir-utils.mjs
@@ -0,0 +1,43 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+const copyBuffer=(buffer,rate=buffer.sampleRate)=>{
+  const channels=Array.from({length:buffer.numberOfChannels},(_,i)=>new Float32Array(buffer.getChannelData(i)));
+  return {sampleRate:rate,numberOfChannels:channels.length,length:channels[0]?.length||0,getChannelData:i=>channels[i]};
+};
+export async function decodeIR(context,bytes) {
+  const decoded=await context.decodeAudioData(bytes.slice(0));
+  return resampleIR(decoded,context.sampleRate);
+}
+export function resampleIR(buffer,targetRate) {
+  if(!Number.isFinite(targetRate)||targetRate<8000||targetRate>96000||!buffer?.numberOfChannels||buffer.numberOfChannels>4||!buffer.length) throw new RangeError('Invalid IR or target sample rate');
+  if(buffer.sampleRate===targetRate) return copyBuffer(buffer,targetRate);
+  const length=Math.max(1,Math.round(buffer.length*targetRate/buffer.sampleRate));
+  const channels=[];
+  for(let ch=0;ch<buffer.numberOfChannels;ch++) {
+    const input=buffer.getChannelData(ch), output=new Float32Array(length), ratio=buffer.sampleRate/targetRate;
+    for(let i=0;i<length;i++) {const x=i*ratio, a=Math.min(Math.floor(x),input.length-1), b=Math.min(a+1,input.length-1), f=x-a;output[i]=input[a]*(1-f)+input[b]*f;}
+    channels.push(output);
+  }
+  return {sampleRate:targetRate,numberOfChannels:channels.length,length,getChannelData:i=>channels[i]};
+}
+export function trimIR(buffer,{thresholdDb=-80}={}) {
+  if(!Number.isFinite(thresholdDb)||thresholdDb>0||thresholdDb<-160) throw new RangeError('Invalid trim threshold');
+  const channels=Array.from({length:buffer.numberOfChannels},(_,i)=>buffer.getChannelData(i));
+  const threshold=10**(thresholdDb/20);let first=buffer.length,last=-1;
+  for(let i=0;i<buffer.length;i++) {let peak=0;for(const channel of channels) peak=Math.max(peak,Math.abs(channel[i]));if(peak>=threshold){first=Math.min(first,i);last=i;}}
+  if(last<0) first=last=0;
+  const result=channels.map(channel=>channel.slice(first,last+1));
+  return {buffer:{sampleRate:buffer.sampleRate,numberOfChannels:result.length,length:result[0]?.length||0,getChannelData:i=>result[i]},startFrame:first,endFrame:last+1};
+}
+export function normalizeIR(buffer,{peak=0.5}={}) {
+  if(!Number.isFinite(peak)||peak<=0||peak>1) throw new RangeError('Peak must be in (0, 1]');
+  const channels=Array.from({length:buffer.numberOfChannels},(_,i)=>new Float32Array(buffer.getChannelData(i)));
+  let max=0;for(const channel of channels) for(const value of channel) max=Math.max(max,Math.abs(value));
+  const gain=max===0?1:peak/max;for(const channel of channels) for(let i=0;i<channel.length;i++) channel[i]*=gain;
+  return {sampleRate:buffer.sampleRate,numberOfChannels:channels.length,length:channels[0]?.length||0,getChannelData:i=>channels[i]};
+}
+export function prepareIR(context,buffer,{trim=false,normalize=true,peak=0.5,thresholdDb=-80}={}) {
+  let result=resampleIR(buffer,context.sampleRate);
+  if(trim) result=trimIR(result,{thresholdDb}).buffer;
+  if(normalize) result=normalizeIR(result,{peak});
+  return result;
+}
--- a/frontend/vendor/jamesdsp/jamesdsp-feature.js
+++ b/frontend/vendor/jamesdsp/jamesdsp-feature.js
@@ -0,0 +1,246 @@
+/* Lazy classic-script bridge for the optional JamesDSP ES module and worklet. */
+(function (root) {
+  'use strict';
+
+  let irToolsPromise;
+  const irTools = () => irToolsPromise ||= Promise.all([
+    import(root.Lazy.url('/vendor/jamesdsp/ir-utils.mjs')),
+    import(root.Lazy.url('/vendor/jamesdsp/ir-builtins.mjs')),
+    import(root.Lazy.url('/vendor/jamesdsp/ir-store.mjs')),
+  ]).then(([utils,builtins,store])=>({utils,builtins,store}));
+
+  const PRESETS = Object.freeze({
+    flat: { name: 'Flat', params: {} },
+    bass: { name: 'Bass', params: { 'eq.enabled': 1, 'eq.band0': 4, 'eq.band1': 3, 'bass.enabled': 1, 'bass.boost': 5, gain: -3 } },
+    vocal: { name: 'Vocal', params: { 'eq.enabled': 1, 'eq.band5': 2, 'eq.band7': 3, 'eq.band9': 2, 'compressor.enabled': 1 } },
+    loudness: { name: 'Loudness', params: { 'limiter.threshold': -3, gain: 2 } },
+    headphone: { name: 'Headphone', params: { 'crossfeed.enabled': 1, 'crossfeed.mode': 1 } },
+    bright: { name: 'Bright', params: { 'eq.enabled': 1, 'eq.band9': 2, 'eq.band10': 3, 'eq.band11': 3, 'eq.band12': 2 } },
+    warm: { name: 'Warm', params: { 'eq.enabled': 1, 'eq.band0': 3, 'eq.band1': 2, 'eq.band7': -1, gain: -2 } },
+  });
+
+  const clampGain = value => Math.max(-24, Math.min(12, Number(value) || 0));
+
+  function createController(options) {
+    const graph = options.graph;
+    let desired = false, active = false, bypassed = false, nodeEntry = null, gainNode = null, context = null;
+    let elements = [], standardInput = null, levelDb = 0, settings = null;
+    let tail = Promise.resolve(), maxLiveHeaps = 0, liveHeaps = 0, nodesCreated = 0, nodesDestroyed = 0, loadedIRRef = null;
+    let faultListener = null, notifying = false, dspAnalyser = null;
+
+    const serial = fn => {
+      const result = tail.then(fn, fn);
+      tail = result.catch(() => {});
+      return result;
+    };
+
+    function snapshot() { return { active, desired, bypassed, route: active && !bypassed ? 'jamesdsp' : 'standard', liveHeaps, maxLiveHeaps, nodesCreated, nodesDestroyed, sampleRate: context?.sampleRate || null, irRef: loadedIRRef }; }
+
+    function routeStandard() {
+      if (!elements.length) return;
+      try {
+        graph.routeAll(elements, standardInput || context?.destination);
+      } catch (error) {
+        try { if (context?.destination) graph.routeAll(elements, context.destination); } catch { /* direct graph route is the last audible fallback */ }
+        throw error;
+      }
+    }
+
+    function releaseNode() {
+      const entry = nodeEntry;
+      nodeEntry = null;
+      if (faultListener && entry) entry.node.removeEventListener('error', faultListener);
+      faultListener = null;
+      try { entry?.node.node.disconnect(); } catch { /* already disconnected */ }
+      try { gainNode?.disconnect(); } catch { /* already disconnected */ }
+      gainNode = null;
+      try { dspAnalyser?.disconnect(); } catch { /* already disconnected */ }
+      dspAnalyser = null;
+      if (entry) {
+        try { entry.node.destroy(); } catch { /* continue freeing references */ }
+        loadedIRRef = null;
+        if (entry.live) { entry.live = false; liveHeaps = Math.max(0, liveHeaps - 1); nodesDestroyed++; }
+      }
+    }
+
+    function fail(error) {
+      desired = false;
+      active = false;
+      bypassed = false;
+      try { routeStandard(); } catch { /* graph route has already tried a direct audible fallback */ }
+      releaseNode();
+      if (!notifying) {
+        notifying = true;
+        try { options.onError?.(error instanceof Error ? error : new Error(String(error || 'JamesDSP failed'))); }
+        finally { notifying = false; }
+      }
+    }
+
+    function rampGain(value) {
+      if (!gainNode || !context) return;
+      const param = gainNode.gain;
+      const now = context.currentTime || 0;
+      if (context.state !== 'running' || typeof param.linearRampToValueAtTime !== 'function') {
+        param.value = value;
+        return;
+      }
+      param.cancelScheduledValues?.(now);
+      param.setValueAtTime?.(param.value, now);
+      param.linearRampToValueAtTime(value, now + 0.018);
+    }
+
+    async function configure(instance, nextSettings, nextLevelDb) {
+      const preset = PRESETS[nextSettings?.preset] || PRESETS.flat;
+      const params = { ...preset.params, ...(nextSettings?.params || {}) };
+      if (Number(params['spatial.enabled']) && Number(params['crossfeed.enabled'])) params['crossfeed.enabled'] = 0;
+      params.gain = clampGain((Number(params.gain) || 0) + (Number(nextLevelDb) || 0));
+      params.bypass = 1;
+      if (active && context?.state === 'running') {
+        rampGain(0);
+        await new Promise(resolve => setTimeout(resolve, 20));
+      }
+      await instance.setBypass(true);
+      const ref = nextSettings?.irRef;
+      const needsIR = ref && (loadedIRRef?.name !== ref.name || loadedIRRef?.hash !== ref.hash);
+      await instance.applyPreset(needsIR ? { params, irRef: ref } : params);
+      if (needsIR) loadedIRRef = { name: ref.name, hash: ref.hash };
+      await instance.setParam('gain', params.gain);
+      if (desired) await instance.setBypass(bypassed);
+      if (desired) rampGain(1);
+    }
+
+    async function loadNode(audioContext) {
+      const moduleURL = root.Lazy.url('/vendor/jamesdsp/jamesdsp-node.mjs');
+      const { JamesDSPNode } = await import(moduleURL);
+      return JamesDSPNode.create(audioContext, {
+        wasmURL: root.Lazy.url('/vendor/jamesdsp/dsp/jamesdsp.wasm'),
+        paramsURL: root.Lazy.url('/vendor/jamesdsp/params.mjs'),
+        workletURL: root.Lazy.url('/vendor/jamesdsp/worklet.mjs'),
+      });
+    }
+
+    async function enable(nextSettings, nextLevelDb = levelDb) {
+      desired = true;
+      settings = nextSettings || {};
+      levelDb = Number(nextLevelDb) || 0;
+      return serial(async () => {
+        if (!desired) return false;
+        const prepared = await options.prepareGraph();
+        context = prepared.context;
+        elements = prepared.elements;
+        standardInput = prepared.standardInput;
+        if (!Number.isFinite(context?.sampleRate) || context.sampleRate < 8000 || context.sampleRate > 96000) throw new RangeError(`JamesDSP supports 8–96 kHz; this device uses ${context?.sampleRate || 'unknown'} Hz`);
+        if (!desired) return false;
+        let instance = nodeEntry?.node;
+        if (!instance) {
+          instance = await (options.loadNode || loadNode)(context);
+          if (!desired) { try { instance.destroy(); } catch {} return false; }
+          nodeEntry = { node: instance, live: true };
+          liveHeaps++; nodesCreated++; maxLiveHeaps = Math.max(maxLiveHeaps, liveHeaps);
+          faultListener = event => fail(event.detail || new Error('JamesDSP processing failed'));
+          instance.addEventListener('error', faultListener);
+          gainNode = context.createGain();
+          gainNode.gain.value = 1;
+          instance.node.connect(gainNode);
+          gainNode.connect(context.destination);
+        }
+        if (!desired) { releaseNode(); return false; }
+        await configure(instance, settings, levelDb);
+        if (!desired) { releaseNode(); return false; }
+        if (context.state === 'suspended') await context.resume().catch(() => {});
+        graph.routeAll(elements, bypassed ? standardInput : instance.node);
+        active = true;
+        return true;
+      }).catch(error => { fail(error); throw error; });
+    }
+
+    function disable() {
+      desired = false;
+      bypassed = false;
+      if (active) {
+        active = false;
+        try { routeStandard(); } catch { /* routeStandard tried its direct fallback */ }
+      }
+      return serial(async () => { releaseNode(); return true; });
+    }
+
+    function setLevelDb(value) {
+      levelDb = Number(value) || 0;
+      if (!desired) return Promise.resolve(false);
+      return enable(settings, levelDb);
+    }
+
+    function changeBypass(value) {
+      if (!nodeEntry) return Promise.resolve(false);
+      return serial(async () => {
+        const next = Boolean(value);
+        if (next === bypassed) return bypassed;
+        // A/B bypass is an exact route around the worklet. This preserves the
+        // Standard graph sample-for-sample instead of relying on DSP bypass math.
+        if (!next) await nodeEntry.node.setBypass(false);
+        if (active) {
+          rampGain(0);
+          await new Promise(resolve => setTimeout(resolve, 20));
+          graph.routeAll(elements, next ? standardInput : nodeEntry.node);
+          rampGain(next ? 0 : 1);
+        }
+        if (next) await nodeEntry.node.setBypass(true);
+        bypassed = next;
+        return bypassed;
+      }).catch(error => { fail(error); throw error; });
+    }
+
+    function setBypass(value) { return changeBypass(value); }
+    function toggleBypass() { return changeBypass(!bypassed); }
+
+    function loadIR(buffer, reference = null) {
+      if (!active || !nodeEntry) return Promise.reject(new Error('Enable JamesDSP before loading an impulse response'));
+      return serial(async () => {
+        if (!active || !nodeEntry) throw new Error('JamesDSP is no longer active');
+        rampGain(0);
+        try { await nodeEntry.node.loadIR(buffer, reference); loadedIRRef = reference ? { name: reference.name, hash: reference.hash } : null; await nodeEntry.node.setParam('convolver.enabled', 1); }
+        finally { if (active && desired) rampGain(1); }
+        return true;
+      }).catch(error => { fail(error); throw error; });
+    }
+
+    function analyser() {
+      if (!active || !gainNode || !context) return null;
+      if (!dspAnalyser) {
+        dspAnalyser = context.createAnalyser();
+        dspAnalyser.fftSize = 128;
+        dspAnalyser.smoothingTimeConstant = 0.78;
+        gainNode.disconnect();
+        gainNode.connect(dspAnalyser);
+        dspAnalyser.connect(context.destination);
+      }
+      return dspAnalyser;
+    }
+
+    return { enable, disable, setLevelDb, setBypass, toggleBypass, loadIR, analyser, get active() { return active; }, get desired() { return desired; }, state: snapshot };
+  }
+
+  async function generateIR(name, sampleRate, channels = 2, maxFrames = 65536) {
+    const {builtins}=await irTools();
+    return builtins.generateIR(name,sampleRate,channels,{maxFrames});
+  }
+  async function decodeIR(context, bytes) { const {utils}=await irTools();return utils.decodeIR(context,bytes); }
+  async function prepareIR(context, buffer, maxFrames = 65536) {
+    const {utils}=await irTools();
+    const rate=context.sampleRate===44100?44100:48000;
+    const prepared=utils.resampleIR(utils.prepareIR(context,buffer,{normalize:false}),rate);
+    if (![1,2,4].includes(prepared.numberOfChannels) || prepared.length<1 || prepared.length>Math.min(65536,maxFrames)) throw new RangeError(`Impulse response exceeds the ${Math.min(65536,maxFrames)}-frame internal limit`);
+    return prepared;
+  }
+  async function saveIR(name, buffer, metadata) { const {store}=await irTools();return store.saveIR(name,buffer,metadata); }
+  async function getIR(name) { const {store}=await irTools();return store.getIR(name); }
+  async function listIRs() { const {store}=await irTools();return store.listIRs(); }
+  async function deleteIR(name) { const {store}=await irTools();return store.deleteIR(name); }
+
+  const api = { PRESETS, createController, generateIR, decodeIR, prepareIR, saveIR, getIR, listIRs, deleteIR };
+  if (typeof module !== 'undefined' && module.exports) module.exports = api;
+  else {
+    root.YT = root.YT || {};
+    root.YT.JamesDSPFeature = api;
+  }
+})(typeof window !== 'undefined' ? window : globalThis);
--- a/frontend/vendor/jamesdsp/jamesdsp-node.mjs
+++ b/frontend/vendor/jamesdsp/jamesdsp-node.mjs
@@ -0,0 +1,84 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+function assetURL(path, fallback) { return globalThis.Lazy?.url?.(path) || new URL(fallback, import.meta.url); }
+const [parameterAPI, irUtils, irStore] = await Promise.all([
+  import(assetURL('/vendor/jamesdsp/params.mjs', './params.mjs')),
+  import(assetURL('/vendor/jamesdsp/ir-utils.mjs', './ir-utils.mjs')),
+  import(assetURL('/vendor/jamesdsp/ir-store.mjs', './ir-store.mjs')),
+]);
+const {DEFAULT_PARAMS, validateParam} = parameterAPI;
+const {prepareIR,resampleIR} = irUtils;
+const {getIR} = irStore;
+const moduleLoads = new WeakMap();
+export class JamesDSPNode extends EventTarget {
+  static async create(context, {wasmURL=assetURL('/vendor/jamesdsp/dsp/jamesdsp.wasm','./dsp/jamesdsp.wasm'), workletURL=assetURL('/vendor/jamesdsp/worklet.mjs','./worklet.mjs')}={}) {
+    if (!Number.isFinite(context.sampleRate)||context.sampleRate<8000||context.sampleRate>96000) throw new RangeError('AudioContext rate must be 8–96 kHz');
+    if (!moduleLoads.has(context)) moduleLoads.set(context,new Map());
+    const cache=moduleLoads.get(context), key=String(workletURL);
+    if (!cache.has(key)) cache.set(key,context.audioWorklet.addModule(workletURL).catch(e=>{cache.delete(key);throw e;}));
+    const response=await fetch(wasmURL);
+    if (!response.ok) throw new Error(`WASM fetch failed: ${response.status}`);
+    const wasmBytes=await response.arrayBuffer();
+    await cache.get(key);
+    const wrapper=new JamesDSPNode(context,wasmBytes);
+    try { await wrapper.ready; return wrapper; } catch(e) { wrapper.destroy(); throw e; }
+  }
+  constructor(context,wasmBytes) {
+    super(); this.context=context; this.defaultParams=Object.fromEntries(Object.entries(DEFAULT_PARAMS).filter(([name])=>!/^(?:liveprog|ddc|arbitrary)\./.test(name))); this.params={...this.defaultParams}; this.pending=new Map(); this.serial=0; this.destroyed=false; this.source=null; this.irRef=null;
+    this.node=new AudioWorkletNode(context,'jamesdsp',{numberOfInputs:1,numberOfOutputs:1,outputChannelCount:[2],channelCount:2,channelCountMode:'explicit',processorOptions:{wasmBytes}});
+    this.ready=new Promise((resolve,reject)=> {
+      const timer=setTimeout(()=>reject(new Error('DSP initialization timed out')),15000);
+      this.node.onprocessorerror=()=>{const error=new Error('DSP processor stopped');clearTimeout(timer);reject(error);this.fail(error);};
+      this.node.port.onmessage=({data})=> {
+        if(data.type==='ready') {clearTimeout(timer);resolve();}
+        else if(data.type==='reply') { const p=this.pending.get(data.id); if(p) {this.pending.delete(data.id);clearTimeout(p.timer);data.error?p.reject(new Error(data.error)):p.resolve(data.result);} }
+        else if(data.type==='error') {const error=new Error(data.error); clearTimeout(timer); reject(error); this.fail(error);}
+        else this.dispatchEvent(new CustomEvent(data.type,{detail:data}));
+      };
+    });
+  }
+  fail(error) { for(const p of this.pending.values()) {clearTimeout(p.timer);p.reject(error);} this.pending.clear();this.dispatchEvent(new CustomEvent('error',{detail:error})); }
+  request(type,data={},transfer=[]) {
+    if(this.destroyed) return Promise.reject(new Error('DSP has been destroyed'));
+    const id=++this.serial;
+    return new Promise((resolve,reject)=> {
+      const timer=setTimeout(()=>{this.pending.delete(id);reject(new Error(`DSP ${type} timed out`));},15000);
+      this.pending.set(id,{resolve,reject,timer});this.node.port.postMessage({type,id,...data},transfer);
+    });
+  }
+  // One source → this DSP → destination. For arbitrary graphs use .node directly.
+  connect(source,destination=this.context.destination) {
+    if(this.destroyed) throw new Error('DSP has been destroyed');
+    if(this.source) this.source.disconnect(this.node);
+    this.node.disconnect();this.source=source;source.connect(this.node);this.node.connect(destination);return destination;
+  }
+  async setParam(name,value) {if(/^(?:liveprog|ddc|arbitrary)\./.test(name))throw new Error('Text effects are disabled in this player version');validateParam(name,value);await this.request('param',{name,value});this.params[name]=value;}
+  setBypass(enabled) {return this.setParam('bypass',Number(Boolean(enabled)));}
+  async setText(effect,text) {
+    throw new Error('Text effects are disabled in this player version');
+  }
+  async loadIR(buffer,reference=null) {
+    buffer=prepareIR(this.context,buffer,{normalize:false});
+    const internalRate=this.context.sampleRate===44100?44100:48000;
+    buffer=resampleIR(buffer,internalRate);
+    if(![1,2,4].includes(buffer.numberOfChannels) || buffer.length>65536 || buffer.length<1) throw new RangeError('IR must have 1, 2, or 4 channels and at most 65536 frames');
+    const pcm=new Float32Array(buffer.length*buffer.numberOfChannels);
+    for(let ch=0;ch<buffer.numberOfChannels;ch++) {const data=buffer.getChannelData(ch);for(let i=0;i<buffer.length;i++) pcm[i*buffer.numberOfChannels+ch]=data[i];}
+    await this.request('ir',{pcm,frames:buffer.length,channels:buffer.numberOfChannels,sourceRate:internalRate},[pcm.buffer]);this.params['convolver.enabled']=0;this.irRef=reference?{name:reference.name,hash:reference.hash}:null;
+  }
+  async getInfo() {const {bytes,heapBytes}=await this.request('info');const view=new DataView(bytes);return {abiVersion:view.getUint32(0,true),structBytes:view.getUint32(4,true),contextRate:view.getFloat32(8,true),internalRate:view.getFloat32(12,true),srcBackend:view.getUint32(16,true),latencyFrames:view.getUint32(20,true),irChannels:view.getUint32(24,true),irFrames:view.getUint32(28,true),irCapFrames:view.getUint32(32,true),headFrames:view.getUint32(36,true),tailFrames:view.getUint32(40,true),liveBytes:view.getUint32(44,true),peakBytes:view.getUint32(48,true),faults:view.getUint32(52,true),underruns:view.getUint32(56,true),overflows:view.getUint32(60,true),heapBytes};}
+  async applyPreset(preset) {
+    // All keys validated before mutation; applying a preset resets unspecified params.
+    if(preset?.texts && Object.keys(preset.texts).length) throw new Error('Text effects are disabled in this player version');
+    const params={...this.defaultParams,...(preset.params||preset)};
+    for(const [name,value] of Object.entries(params)) {if(/^(?:liveprog|ddc|arbitrary)\./.test(name))throw new Error('Text effects are disabled in this player version');validateParam(name,value);}
+    if(preset.irRef) {const saved=await getIR(preset.irRef.name);if(!saved||saved.hash!==preset.irRef.hash)throw new Error(`Preset IR is missing or changed: ${preset.irRef.name}`);await this.loadIR(saved.buffer,preset.irRef);}
+    // Configure before enabling; the referenced IR is loaded first.
+    for(const [name,value] of Object.entries(params).sort(([a],[b])=>Number(a.endsWith('.enabled'))-Number(b.endsWith('.enabled')))) await this.setParam(name,value);
+  }
+  toJSON() {return {version:2,params:{...this.params},...(this.irRef?{irRef:{...this.irRef}}:{})};}
+  destroy() {
+    if(this.destroyed) return;
+    if(this.source) {try {this.source.disconnect(this.node);} catch {}} this.node.disconnect();
+    this.node.port.postMessage({type:'destroy'});this.destroyed=true;this.fail(new Error('DSP destroyed'));this.node.port.close();
+  }
+}
--- a/frontend/vendor/jamesdsp/params.mjs
+++ b/frontend/vendor/jamesdsp/params.mjs
@@ -0,0 +1,31 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+export const EQ_FREQUENCIES = [25,40,63,100,160,250,400,630,1000,1600,2500,4000,6300,10000,16000];
+export const COMP_FREQUENCIES = [95,200,400,800,1600,3400,7500];
+export const EFFECTS = ['eq','compressor','bass','stereo','reverb','crossfeed','spatial','tube','convolver','liveprog','ddc','arbitrary'];
+export const PARAMS = {
+  bypass:[0,1,0], gain:[-24,12,0],
+  'limiter.threshold':[-24,0,-0.1], 'limiter.release':[10,1000,100],
+  'eq.mode':[0,5,1], 'eq.interpolation':[0,1,0],
+  'compressor.time':[0.01,2,0.1], 'compressor.mode':[0,3,3], 'compressor.granularity':[0,4,0],
+  'bass.boost':[0,12,6], 'stereo.mix':[0,1,0.5], 'reverb.preset':[0,18,0],
+  'convolver.mix':[0,1,1], 'convolver.predelayMs':[0,250,0],
+  'crossfeed.mode':[0,5,0], 'tube.drive':[-12,12,0],
+  'spatial.mode':[2,6,2], 'spatial.azimuth':[-90,90,0], 'spatial.spread':[0,120,60],
+  'spatial.distance':[0.5,5,1], 'spatial.room':[0,1,0], 'spatial.centerDb':[0,6,0], 'spatial.mix':[0,1,1],
+};
+for (const effect of EFFECTS) PARAMS[`${effect}.enabled`] = [0,1,0];
+EQ_FREQUENCIES.forEach((_, i) => PARAMS[`eq.band${i}`] = [-12,12,0]);
+COMP_FREQUENCIES.forEach((_, i) => PARAMS[`compressor.band${i}`] = [-12,12,0]);
+export const DEFAULT_PARAMS = Object.fromEntries(Object.entries(PARAMS).map(([k,v])=>[k,v[2]]));
+export function validateParam(name, value) {
+  const spec=PARAMS[name];
+  if (!spec || typeof value!=='number' || !Number.isFinite(value) || value<spec[0] || value>spec[1]) throw new RangeError(`Invalid parameter ${name}: ${value}`);
+  if ((name.endsWith('.enabled') || /mode|preset|granularity|interpolation|bypass/.test(name)) && !Number.isInteger(value)) throw new RangeError(`${name} requires an integer`);
+}
+export const PRESETS = {
+  Flat: {},
+  'Warm lows': {'eq.band0':4,'eq.band1':4,'eq.band2':3,'eq.band3':2,'eq.enabled':1,'gain':-3},
+  'Headphones': {'crossfeed.enabled':1,'crossfeed.mode':1,'eq.band8':-2,'eq.enabled':1},
+  'Small room': {'reverb.preset':7,'reverb.enabled':1,'gain':-3},
+  'Virtual speakers': {'spatial.enabled':1,'spatial.mode':6,'spatial.spread':90},
+};
--- a/frontend/vendor/jamesdsp/worklet.mjs
+++ b/frontend/vendor/jamesdsp/worklet.mjs
@@ -0,0 +1,57 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+import createJamesDSP from './dsp/jamesdsp-a982b53.mjs';
+class JamesDSPProcessor extends AudioWorkletProcessor {
+  constructor(options) {
+    super(); this.closed=false;this.failed=false;
+    this.initialize(options);
+  }
+  async initialize(options) {
+    try {
+      this.wasm=await createJamesDSP({wasmBinary:options.processorOptions.wasmBytes,locateFile:()=>'jamesdsp.wasm',print:()=>{},printErr:()=>{}});
+      this.handle=this.wasm._jdsp_create(sampleRate);
+      this.pointer=this.wasm._malloc(128*2*4);
+      if(!this.handle || !this.pointer) throw new Error('DSP allocation failed or sample rate unsupported');
+      this.audio=this.wasm.HEAPF32.subarray(this.pointer/4,this.pointer/4+256);
+      this.port.onmessage=({data})=>this.message(data);
+      this.port.postMessage({type:'ready'});
+    } catch(error) {this.failed=true;this.port.postMessage({type:'error',error:String(error)});}
+  }
+  string(value,fn) {
+    const utf8=encodeURIComponent(value+'\0').replace(/%([0-9A-F]{2})/g,(_,hex)=>String.fromCharCode(parseInt(hex,16)));
+    const bytes=Uint8Array.from(utf8,c=>c.charCodeAt(0)), p=this.wasm._malloc(bytes.length);
+    if(!p) throw new Error('DSP text allocation failed');
+    try {this.wasm.HEAPU8.set(bytes,p);return fn(p);} finally {this.wasm._free(p);}
+  }
+  message(data) {
+    if(data.type==='destroy') {if(this.handle) this.wasm._jdsp_destroy(this.handle);if(this.pointer) this.wasm._free(this.pointer);this.closed=true;return;}
+    try {
+      let result;
+      if(data.type==='param') result=this.string(data.name,p=>this.wasm._jdsp_set_param(this.handle,p,data.value));
+      else if(data.type==='ir') {
+        const p=this.wasm._malloc(data.pcm.byteLength);if(!p) throw new Error('IR allocation failed');
+        try {this.wasm.HEAPF32.set(data.pcm,p/4);result=this.wasm._jdsp_load_ir_ex(this.handle,p,data.frames,data.channels,data.sourceRate);} finally {this.wasm._free(p);}
+      } else if(data.type==='info') {
+        const p=this.wasm._malloc(64);if(!p)throw new Error('DSP info allocation failed');
+        try {result=this.wasm._jdsp_get_info(this.handle,p);if(result===0){const bytes=this.wasm.HEAPU8.slice(p,p+64);this.port.postMessage({type:'reply',id:data.id,result:{bytes:bytes.buffer,heapBytes:this.wasm.HEAPU8.buffer.byteLength}},[bytes.buffer]);return;}} finally {this.wasm._free(p);}
+      } else throw new Error('Unknown DSP message');
+      if(result!==0) throw new Error(`DSP rejected ${data.name||data.effect||data.type}`);
+      this.port.postMessage({type:'reply',id:data.id,result});
+    } catch(error) {this.port.postMessage({type:'reply',id:data.id,error:String(error)});}
+  }
+  process(inputs,outputs) {
+    if(this.closed) return false;
+    const out=outputs[0], input=inputs[0];
+    if(!out?.length || this.failed || !this.handle) return true;
+    // Mono duplicates to stereo; missing input becomes silence, preserving tails.
+    for(let offset=0;offset<out[0].length;offset+=128) {
+      const n=Math.min(128,out[0].length-offset);
+      for(let i=0;i<n;i++) {this.audio[i*2]=input[0]?.[offset+i]||0;this.audio[i*2+1]=(input[1]||input[0])?.[offset+i]||0;}
+      try {
+        if(this.wasm._jdsp_process(this.handle,this.pointer,n)!==0) throw new Error('DSP produced nonfinite output');
+        for(let i=0;i<n;i++) {out[0][offset+i]=this.audio[i*2];if(out[1]) out[1][offset+i]=this.audio[i*2+1];}
+      } catch(error) {out.forEach(channel=>channel.fill(0));this.failed=true;this.port.postMessage({type:'error',error:String(error)});break;}
+    }
+    return true;
+  }
+}
+registerProcessor('jamesdsp',JamesDSPProcessor);
--- a/frontend/views-core.js
+++ b/frontend/views-core.js
@@ -1,4 +1,18 @@
 /* Eager UI definitions. Read app lexical state only when called after initialization. */
+function parseJamesDspPreset(text) {
+  const imported = typeof text === 'string' ? JSON.parse(text) : text;
+  const allowed = /^(?:eq\.band(?:[0-9]|1[0-4])|compressor\.band[0-6]|(?:eq|compressor|bass|stereo|reverb|crossfeed|tube|convolver)\.enabled|(?:gain|limiter\.threshold|limiter\.release|eq\.mode|eq\.interpolation|compressor\.time|compressor\.mode|compressor\.granularity|bass\.boost|stereo\.mix|reverb\.preset|crossfeed\.mode|tube\.drive))$/;
+  if (imported?.version !== 1 || imported?.texts || !imported?.params || typeof imported.params !== 'object' || Array.isArray(imported.params)) throw new Error('This file is not a supported preset (text effects are disabled).');
+  const range = key => key.startsWith('eq.band') || key.startsWith('compressor.band') ? [-12, 12] : ({ gain: [-24, 12], 'limiter.threshold': [-24, 0], 'limiter.release': [10, 1000], 'eq.mode': [0, 5], 'eq.interpolation': [0, 1], 'compressor.time': [0.01, 2], 'compressor.mode': [0, 3], 'compressor.granularity': [0, 4], 'bass.boost': [0, 12], 'stereo.mix': [0, 1], 'reverb.preset': [0, 18], 'crossfeed.mode': [0, 5], 'tube.drive': [-12, 12] }[key] || (key.endsWith('.enabled') ? [0, 1] : null));
+  for (const [key, value] of Object.entries(imported.params)) {
+    const bounds = range(key);
+    if (!allowed.test(key) || typeof value !== 'number' || !Number.isFinite(value) || !bounds || value < bounds[0] || value > bounds[1] || (key === 'convolver.enabled' && value !== 0)) throw new Error(`Unsupported preset setting: ${key}`);
+    if ((key.endsWith('.enabled') || /mode|preset|granularity|interpolation/.test(key)) && !Number.isInteger(value)) throw new Error(`Preset setting must be a whole number: ${key}`);
+  }
+  const presets = ['flat', 'bass', 'vocal', 'loudness', 'headphone', 'bright', 'warm'];
+  return { preset: presets.includes(imported.preset) ? imported.preset : 'flat', params: { ...imported.params } };
+}
+
 async function renderLibrary() {
  els.listTitle.textContent = 'Library';
  resetListHeaderExtras();
@@ -718,10 +732,19 @@ async function renderSettings() {
  const qOptions = qualities
    .map((q) => `<option value="${q}"${data.settings.quality === q ? ' selected' : ''}>${q === 'auto' ? 'Auto' : q}</option>`)
    .join('');
+  const jamesDsp = data.settings.jamesDsp || { enabled: false, downloadForOffline: false, preset: 'flat', params: {}, irRef: null };
+  const dspCores=Number(navigator.hardwareConcurrency), dspMemory=Number(navigator.deviceMemory);
+  const dspLowEnd=(dspCores>0&&dspCores<=4)||(dspMemory>0&&dspMemory<=4);
+  const dspBands = [25, 40, 63, 100, 160, 250, 400, 630, 1000, 1600, 2500, 4000, 6300, 10000, 16000];
+  const dspParamDefaults = { 'bass.boost': 6, 'stereo.mix': 0.5, 'limiter.threshold': -0.1, 'convolver.mix': 1, 'convolver.predelayMs': 0, 'spatial.mode': 6, 'spatial.spread': 60, 'spatial.distance': 1, 'spatial.mix': 1 };
+  const dspParam = key => Number.isFinite(Number(jamesDsp.params?.[key])) ? Number(jamesDsp.params[key]) : (dspParamDefaults[key] ?? 0);
+  const dspRange = (key, label, min, max, step = 1, unit = '') => `<label class="set-row dsp-param-row"><span>${label}<small>${dspParam(key)}${unit}</small></span><input type="range" data-dsp-param="${key}" min="${min}" max="${max}" step="${step}" value="${dspParam(key)}" /></label>`;
+  const dspBandRows = dspBands.map((hz, i) => dspRange(`eq.band${i}`, `${hz >= 1000 ? (hz / 1000) + ' kHz' : hz + ' Hz'}`, -12, 12, 0.5, ' dB')).join('');

-  const sel = (id, val, opts) => `<select id="${id}" class="set-select">` +
+  const sel = (id, val, opts) => `<span class="set-control-wrap"><select id="${id}" class="set-select">` +
    opts.map(([v, label]) => `<option value="${v}"${val === v ? ' selected' : ''}>${label}</option>`).join('') +
-    `</select>`;
+    `</select></span>`;
+  const dspBuiltinIRSelect = `<select id="setDspBuiltinIR" class="set-select">${['Small room','Hall','Plate','Cathedral'].map(name=>`<option value="${name}"${dspLowEnd&&name!=='Small room'?' disabled':''}>${name}</option>`).join('')}</select>`;

  wrap.innerHTML = `
    <div class="set-group">
@@ -788,6 +811,50 @@ async function renderSettings() {
        </span>
        <input id="setLiveAudioIOS" type="checkbox" ${data.settings.liveAudioIOS ? 'checked' : ''} />
      </label>` : ''}
+      <div class="dsp-settings" id="jamesDspSettings">
+        <div class="set-group-title">Sound engine</div>
+        <label class="set-row"><span>Engine<small>Standard is the default. JamesDSP replaces the Standard EQ and vocal/stereo stages.</small></span>
+          ${sel('setSoundEngine', jamesDsp.enabled ? 'jamesdsp' : 'standard', [['standard', 'Standard'], ['jamesdsp', 'JamesDSP']])}
+        </label>
+        <label class="set-row"><span>Download audio effects for offline<small>Includes the optional JamesDSP engine and its large WASM file in the offline cache.</small></span><input id="setDspOffline" type="checkbox" ${jamesDsp.downloadForOffline ? 'checked' : ''} /></label>
+        <div id="jamesDspControls" ${jamesDsp.enabled ? '' : 'hidden'}>
+          <div class="set-row"><span>Live processing<small>${EQ.isIOS() ? 'On iPhone, enable Live sound processing above first. Audio may stop when the screen locks.' : 'Processing runs on this device.'}</small></span></div>
+          ${dspLowEnd ? '<p class="dsp-risk" role="note">This device may have limited audio headroom. Long impulse responses are disabled and the short room response is capped at 0.5 seconds.</p>' : ''}
+          <label class="set-row"><span>Preset</span>${sel('setDspPreset', jamesDsp.preset || 'flat', [['flat', 'Flat'], ['bass', 'Bass boost'], ['vocal', 'Vocal'], ['loudness', 'Loudness'], ['headphone', 'Headphone crossfeed'], ['bright', 'Bright'], ['warm', 'Warm']])}</label>
+          <div class="dsp-param-list" aria-label="15-band equalizer">${dspBandRows}</div>
+          <label class="set-row"><span>Bass boost<small>${dspParam('bass.boost')} dB</small></span><input type="range" data-dsp-param="bass.boost" min="0" max="12" step="0.5" value="${dspParam('bass.boost')}" /></label>
+          <label class="set-row"><span>Stereo width<small>${Math.round(dspParam('stereo.mix') * 100)}%</small></span><input type="range" data-dsp-param="stereo.mix" min="0" max="1" step="0.05" value="${dspParam('stereo.mix')}" /></label>
+          <label class="set-row"><span>Crossfeed mode</span>${sel('setDspCrossfeed', String(dspParam('crossfeed.mode')), [['0', 'Off'], ['1', 'Gentle'], ['2', 'Natural'], ['3', 'Wide'], ['4', 'Diffuse'], ['5', 'Strong']])}</label>
+          <label class="set-row"><span>Reverb preset</span>${sel('setDspReverb', String(dspParam('reverb.preset')), Array.from({ length: 19 }, (_, i) => [String(i), i === 0 ? 'Off' : `Room ${i}`]))}</label>
+          <label class="set-row"><span>Tube drive<small>${dspParam('tube.drive')} dB</small></span><input type="range" data-dsp-param="tube.drive" min="-12" max="12" step="0.5" value="${dspParam('tube.drive')}" /></label>
+          <label class="set-row"><span>Limiter threshold<small>${dspParam('limiter.threshold')} dB</small></span><input type="range" data-dsp-param="limiter.threshold" min="-24" max="0" step="0.5" value="${dspParam('limiter.threshold')}" /></label>
+          <label class="set-row"><span>Output gain<small>${dspParam('gain')} dB</small></span><input type="range" data-dsp-param="gain" min="-24" max="12" step="0.5" value="${dspParam('gain')}" /></label>
+          <label class="set-row"><span>Compressor</span><input id="setDspCompressor" type="checkbox" ${dspParam('compressor.enabled') ? 'checked' : ''} /></label>
+          <div class="dsp-actions"><button id="dspPresetImportBtn" class="btn" type="button">Import preset JSON</button><button id="dspPresetExportBtn" class="btn" type="button">Export preset JSON</button><button id="dspResetBtn" class="btn" type="button">Reset DSP</button></div>
+          <input id="dspPresetFile" type="file" accept="application/json,.json" hidden />
+          <section class="dsp-subsection" aria-labelledby="dspConvolverTitle">
+            <h4 id="dspConvolverTitle">Convolver</h4>
+            <label class="set-row"><span>Enable convolution</span><input id="setDspConvolver" type="checkbox" ${dspParam('convolver.enabled') ? 'checked' : ''} /></label>
+            <label class="set-row"><span>Dry / wet<small>${Math.round(dspParam('convolver.mix')*100)}%</small></span><input type="range" data-dsp-param="convolver.mix" min="0" max="1" step="0.01" value="${dspParam('convolver.mix')}" /></label>
+            <label class="set-row"><span>Pre-delay<small>${dspParam('convolver.predelayMs')} ms</small></span><input type="range" data-dsp-param="convolver.predelayMs" min="0" max="250" step="1" value="${dspParam('convolver.predelayMs')}" /></label>
+            <label class="set-row"><span>Built-in response</span><span class="set-control-wrap">${dspBuiltinIRSelect}</span></label>
+            <button id="setDspLoadBuiltin" class="btn" type="button">Generate and load</button>
+            <label class="set-row dsp-upload-row"><span>Upload impulse response<small>WAV or other browser-decodable audio; up to 65,536 frames at the internal sample rate.</small></span><span class="dsp-file-control"><input id="dspIrFile" type="file" accept="audio/*,.wav" aria-label="Upload impulse response" /><button id="dspIrChooseFile" class="dsp-file-button" type="button">Choose file</button><span class="dsp-file-name" id="dspIrFileName" aria-live="polite">No file chosen</span></span></label>
+            <label class="set-row"><span>Stored responses</span><span class="set-control-wrap"><select id="setDspSavedIR" class="set-select"><option value="">Choose a saved response</option></select></span></label>
+            <button id="setDspLoadSavedIR" class="btn" type="button">Load saved response</button>
+            <p id="dspIrStatus" class="sp-note">${jamesDsp.irRef?.name ? `Loaded: ${jamesDsp.irRef.name}` : 'No impulse response loaded.'}</p>
+          </section>
+          <section class="dsp-subsection" aria-labelledby="dspSpatialTitle">
+            <h4 id="dspSpatialTitle">3D spatial stage</h4>
+            <label class="set-row"><span>Enable 3D spatial stage</span><input id="setDspSpatial" type="checkbox" ${dspParam('spatial.enabled') ? 'checked' : ''} /></label>
+            <label class="set-row"><span>HRTF / renderer mode</span>${sel('setDspSpatialMode',String(dspParam('spatial.mode')),[['2','HRTF crossfeed'],['3','HRTF surround 1'],['4','HRTF surround 2'],['5','HRTF surround 3'],['6','Virtual speakers']])}</label>
+            ${dspRange('spatial.azimuth','Azimuth',-90,90,1,'°')}
+            ${dspRange('spatial.spread','Speaker spread',0,120,1,'°')}
+            ${dspRange('spatial.distance','Distance',0.5,5,0.1,' m')}
+            ${dspRange('spatial.centerDb','Center boost',0,6,0.1,' dB')}
+          </section>
+        </div>
+      </div>
      <label class="set-row">
        <span>Default volume</span>
        <input id="setVolume" type="range" min="0" max="1" step="0.01" value="${data.settings.volume}" />
@@ -844,13 +911,6 @@ async function renderSettings() {
    <div class="set-group">
      <div class="set-group-title">Offline cache</div>
      <div class="set-row"><span>App &amp; features</span><small id="offlineAssetStatus" role="status">Checking offline readiness…</small></div>
-      <label class="set-row">
-        <span>
-          Auto-save videos I play
-          <small>Every video you open is kept on this device in the background, so it plays offline later.</small>
-        </span>
-        <input id="setAutoSavePlayed" type="checkbox" ${data.settings.autoSavePlayed !== false ? 'checked' : ''} />
-      </label>
      <label class="set-row">
        <span>
          Auto-save playlist videos
@@ -1062,6 +1122,124 @@ async function renderSettings() {
    if (e.target.checked) toast('Live sound processing on — streamed songs go silent when the screen locks', { duration: 4500 });
  });

+  const dspControls = $('jamesDspControls');
+  const dspEngine = $('setSoundEngine');
+  if (dspEngine) dspEngine.addEventListener('change', e => {
+    const enable = e.target.value === 'jamesdsp';
+    if (enable && EQ.isIOS() && !data.settings.liveAudioIOS) {
+      e.target.value = 'standard';
+      toast('On iPhone, turn on Live sound processing first.');
+      return;
+    }
+    data.settings.jamesDsp = data.settings.jamesDsp || { enabled: false, downloadForOffline: false, preset: 'flat', params: {}, irRef: null };
+    data.settings.jamesDsp.enabled = enable;
+    if (enable) data.settings.jamesDsp.downloadForOffline = true;
+    if (enable && $('setDspOffline')) $('setDspOffline').checked = true;
+    if (dspControls) dspControls.hidden = !enable;
+    persist();
+    reportDspOfflineOptIn();
+    EQ.apply();
+  });
+  if ($('setDspOffline')) $('setDspOffline').addEventListener('change', e => {
+    data.settings.jamesDsp = data.settings.jamesDsp || { enabled: false, downloadForOffline: false, preset: 'flat', params: {} };
+    data.settings.jamesDsp.downloadForOffline = e.target.checked;
+    persist();
+    reportDspOfflineOptIn();
+    toast(e.target.checked ? 'Preparing audio effects for offline use' : 'Audio effects removed from the offline completion list');
+  });
+  const dspConfig = data.settings.jamesDsp || (data.settings.jamesDsp = { enabled: false, downloadForOffline: false, preset: 'flat', params: {}, irRef: null });
+  let dspApplyTimer = null;
+  const applyDspSettings = () => {
+    clearTimeout(dspApplyTimer);
+    persist();
+    dspApplyTimer = setTimeout(() => { if (data.settings.jamesDsp?.enabled) EQ.apply(); }, 120);
+  };
+  if ($('setDspPreset')) $('setDspPreset').addEventListener('change', e => {
+    dspConfig.preset = e.target.value;
+    dspConfig.params = {};
+    wrap.querySelectorAll('[data-dsp-param]').forEach(input => { input.value = input.dataset.dspParam === 'limiter.threshold' ? '-0.1' : '0'; });
+    applyDspSettings();
+  });
+  wrap.querySelectorAll('[data-dsp-param]').forEach(input => input.addEventListener('input', () => {
+    const value = Number(input.value);
+    dspConfig.params[input.dataset.dspParam] = value;
+    const small = input.closest('.set-row')?.querySelector('small');
+    if (small) small.textContent = `${value}${input.dataset.dspParam === 'stereo.mix' ? '%' : input.dataset.dspParam === 'bass.boost' || input.dataset.dspParam === 'tube.drive' || input.dataset.dspParam === 'limiter.threshold' || input.dataset.dspParam === 'gain' || input.dataset.dspParam.startsWith('eq.band') ? ' dB' : ''}`;
+    applyDspSettings();
+  }));
+  if ($('setDspCrossfeed')) $('setDspCrossfeed').addEventListener('change', e => { dspConfig.params['crossfeed.mode'] = Number(e.target.value); dspConfig.params['crossfeed.enabled'] = Number(e.target.value) ? 1 : 0; applyDspSettings(); });
+  if ($('setDspConvolver')) $('setDspConvolver').addEventListener('change', e => {
+    const hasIR=dspConfig.irRef||EQ.state().jamesDsp?.irRef;
+    if(e.target.checked&&!hasIR){e.target.checked=false;toast('Load an impulse response first.');return;}
+    dspConfig.params['convolver.enabled']=e.target.checked?1:0;applyDspSettings();
+  });
+  if ($('setDspSpatial')) $('setDspSpatial').addEventListener('change', e => {
+    dspConfig.params['spatial.enabled']=e.target.checked?1:0;
+    if(e.target.checked){dspConfig.params['crossfeed.enabled']=0;if($('setDspCrossfeed'))$('setDspCrossfeed').value='0';}
+    applyDspSettings();
+  });
+  if ($('setDspSpatialMode')) $('setDspSpatialMode').addEventListener('change', e => {dspConfig.params['spatial.mode']=Number(e.target.value);applyDspSettings();});
+  if ($('setDspReverb')) $('setDspReverb').addEventListener('change', e => { dspConfig.params['reverb.preset'] = Number(e.target.value); dspConfig.params['reverb.enabled'] = Number(e.target.value) ? 1 : 0; applyDspSettings(); });
+  if ($('setDspCompressor')) $('setDspCompressor').addEventListener('change', e => { dspConfig.params['compressor.enabled'] = e.target.checked ? 1 : 0; applyDspSettings(); });
+  const refreshDspIrList=async()=>{
+    const select=$('setDspSavedIR');if(!select)return;
+    const selected=select.value;select.replaceChildren(new Option('Choose a saved response',''));
+    try{for(const item of await EQ.listDspIRs())select.add(new Option(`${item.name} · ${item.channels} ch · ${item.frames} frames`,item.name));if([...select.options].some(o=>o.value===selected))select.value=selected;}
+    catch(error){if($('dspIrStatus'))$('dspIrStatus').textContent=`Saved response list unavailable: ${error.message}`;}
+  };
+  if ($('setDspLoadBuiltin')) $('setDspLoadBuiltin').addEventListener('click',async()=>{
+    try{const name=$('setDspBuiltinIR').value;const ref=await EQ.loadDspBuiltinIR(name);if($('dspIrStatus'))$('dspIrStatus').textContent=`Loaded ${name}${ref?' and saved it for this device':' for this session only'}.`;$('setDspConvolver').checked=true;await refreshDspIrList();}
+    catch(error){toast(`Impulse response failed: ${error.message}`);}
+  });
+  if ($('setDspLoadSavedIR')) $('setDspLoadSavedIR').addEventListener('click',async()=>{
+    const name=$('setDspSavedIR').value;if(!name){await refreshDspIrList();return;}
+    try{const ref=await EQ.loadDspSavedIR(name);if($('dspIrStatus'))$('dspIrStatus').textContent=`Loaded saved response: ${name}`;$('setDspConvolver').checked=true;await refreshDspIrList();}
+    catch(error){toast(`Saved response failed: ${error.message}`);}
+  });
+  if ($('dspIrChooseFile')) $('dspIrChooseFile').addEventListener('click', e => { e.preventDefault(); $('dspIrFile')?.click(); });
+  if ($('dspIrFile')) $('dspIrFile').addEventListener('change',async e=>{
+    const file=e.target.files?.[0];if(!file)return;
+    if($('dspIrFileName'))$('dspIrFileName').textContent=file.name;
+    try{const ref=await EQ.loadDspIR(file);if($('dspIrStatus'))$('dspIrStatus').textContent=`Loaded ${ref?.name||file.name}${ref?' and saved it for this device':' for this session only'}.`;$('setDspConvolver').checked=true;await refreshDspIrList();}
+    catch(error){toast(`Impulse response failed: ${error.message}`);}
+    finally{e.target.value='';}
+  });
+  if(jamesDsp.enabled||jamesDsp.downloadForOffline)refreshDspIrList();
+  if ($('dspResetBtn')) $('dspResetBtn').addEventListener('click', () => {
+    dspConfig.preset = 'flat'; dspConfig.params = {};
+    if ($('setDspPreset')) $('setDspPreset').value = 'flat';
+    wrap.querySelectorAll('[data-dsp-param]').forEach(input => { input.value = input.dataset.dspParam === 'limiter.threshold' ? '-0.1' : '0'; });
+    if ($('setDspCrossfeed')) $('setDspCrossfeed').value = '0';
+    if ($('setDspReverb')) $('setDspReverb').value = '0';
+    if ($('setDspCompressor')) $('setDspCompressor').checked = false;
+    applyDspSettings();
+    toast('JamesDSP settings reset');
+  });
+  if ($('dspPresetExportBtn')) $('dspPresetExportBtn').addEventListener('click', () => {
+    const params = { ...(dspConfig.params || {}) }; delete params['convolver.enabled'];
+    const blob = new Blob([JSON.stringify({ version: 1, preset: dspConfig.preset || 'flat', params }, null, 2)], { type: 'application/json' });
+    const url = URL.createObjectURL(blob), a = document.createElement('a');
+    a.href = url; a.download = 'ytplayer-jamesdsp-preset.json'; a.click(); setTimeout(() => URL.revokeObjectURL(url), 1000);
+  });
+  if ($('dspPresetImportBtn')) $('dspPresetImportBtn').addEventListener('click', () => $('dspPresetFile')?.click());
+  if ($('dspPresetFile')) $('dspPresetFile').addEventListener('change', async e => {
+    const file = e.target.files?.[0]; if (!file) return;
+    try {
+      if (file.size > 65536) throw new Error('Preset files must be 64 KB or smaller.');
+      const imported = parseJamesDspPreset(await file.text());
+      dspConfig.preset = imported.preset; dspConfig.params = imported.params;
+      if ($('setDspPreset')) $('setDspPreset').value = dspConfig.preset;
+      applyDspSettings(); toast('JamesDSP preset imported');
+    } catch (error) { toast(error?.message || 'Could not import preset'); }
+    finally { e.target.value = ''; }
+  });
+  if ($('dspIrFile')) $('dspIrFile').addEventListener('change', async e => {
+    const file = e.target.files?.[0]; if (!file) return;
+    try { await EQ.loadDspIR(file); dspConfig.params['convolver.enabled'] = 1; applyDspSettings(); toast('Impulse response loaded for this session'); }
+    catch (error) { toast(error?.message || 'Could not load impulse response'); }
+    finally { e.target.value = ''; }
+  });
+

  // ---- Saved searches manager ----
  {
@@ -1123,10 +1301,6 @@ async function renderSettings() {
    persist();
    Notes.refreshFlags();
  });
-  $('setAutoSavePlayed').addEventListener('change', (e) => {
-    data.settings.autoSavePlayed = e.target.checked;
-    persist();
-  });
  $('setAutoPreload').addEventListener('change', (e) => {
    data.settings.autoPreload = e.target.checked;
    persist();
--- a/perf/README.md
+++ b/perf/README.md
@@ -74,6 +74,11 @@ Each scenario records the following metrics across **5 independent runs** (repor

 ## 4. How to Run

+### Optional JamesDSP integration check
+`node perf/dsp.mjs --browser all` builds short local H.264/AAC test tones, exercises Standard and lazy JamesDSP presets through the real app graph, verifies A/B bypass routes directly to the unchanged Standard chain, measures generated-IR effects and the four-channel/spatial stages in an offline render, checks an arbitrary 32 kHz context, and tests stored-IR offline reload, one worklet heap, no new media sources, and corrupt-WASM fallback. The default install must omit the optional WASM; the harness then opts in through Settings and confirms completion. Detailed measurements stay in ignored `perf/.tmp/dsp-results.json`.
+
+`node perf/settings-persist.mjs --browser all` also round-trips a disabled, custom JamesDSP preset and the offline-audio opt-in through local storage and confirms the Standard selector remains selected.
+
 ### Prerequisites
 Symlink dependencies and ensure server dependencies are installed:
 ```bash
@@ -484,3 +489,24 @@ remote toggles against a mocked relay. Transport previews and remote screenshots
 are saved in ignored `plans/transport-shots/`. Run `node perf/ui-geometry.mjs`
 for the 320–430px search-bar and Saved-row geometry matrix. OS lock-screen buttons
 remain platform-rendered through the existing MediaSession handlers.
+
+Run `node perf/settings-layout.mjs` for the Settings workspace and JamesDSP
+control matrix: Chromium and WebKit, all four layouts, dark/light/contrast, and
+390/768/1280/1440/1920px widths. It checks horizontal overflow, responsive row
+geometry, themed selects and switches, the clipped native file picker, and
+button wrapping; desktop screenshots and measurements are written to
+`plans/settings-shots/`.
+
+## Transient retry verification
+
+`retry.mjs` starts the real Bun server behind the local traffic-shaping proxy, then
+injects one HTTP 503 into search, one dropped related-video request, and one lazy
+chunk load failure. Each path must recover automatically without exposing the
+manual related/player Retry affordance. It runs Chromium and WebKit by default;
+choose `--browser chromium|webkit` and `--profile lte|lossy|unthrottled` to narrow
+it. Retry logic is limited to idempotent GET requests and chunk loads; explicit
+save/retry POST actions remain user initiated.
+
+```bash
+node perf/retry.mjs --browser all --profile lossy
+```
--- a/perf/autosave.mjs
+++ b/perf/autosave.mjs
@@ -94,7 +94,7 @@ execFileSync('ffmpeg', ['-y', '-i', mp4, '-vn', '-c:a', 'copy', path.join(media,
            await page.waitForFunction(key => JSON.parse(localStorage.getItem('_ytpdata')).settings[key] === true, key);
            if (scenario === 'settings-save-first') await page.evaluate(clip => { Player.loadVideo(clip); }, clip);
          }
-          const expected = !['playlist-boot-off'].includes(scenario);
+          const expected = !['open-default', 'open-audio-only', 'open-prefer-stream', 'playlist-boot-off'].includes(scenario);
          if (supported && expected) await page.waitForFunction(id => cachedIds.has(id), clip.id, { timeout: 15000 });
          else await page.waitForTimeout(1000);
          const state = await page.evaluate(async id => ({ cached: cachedIds.has(id), files: OPFS.isSupported() ? await OPFS.listVideos() : [], queue: SaveQueue.pending(), calls: window.__saveCalls }), clip.id);
--- a/perf/dsp.mjs
+++ b/perf/dsp.mjs
@@ -0,0 +1,165 @@
+#!/usr/bin/env node
+// End-to-end JamesDSP checks against the real local server, manifest cache and media fixture.
+import assert from 'node:assert/strict';
+import { spawn, execFileSync } from 'node:child_process';
+import { createRequire } from 'node:module';
+import { createServer } from 'node:net';
+import { mkdtempSync, mkdirSync, cpSync, writeFileSync, statSync, rmSync, existsSync } from 'node:fs';
+import { join, resolve } from 'node:path';
+import { chromium, webkit } from 'playwright';
+import { createThrottleProxy } from './proxy.mjs';
+
+const repo = resolve(import.meta.dirname, '..');
+const requested = process.argv.includes('--browser') ? process.argv[process.argv.indexOf('--browser') + 1] : 'all';
+assert.ok(['all', 'chromium', 'webkit'].includes(requested));
+const scratch = mkdtempSync(join(repo, 'perf/.tmp/dsp-'));
+const results = { results: [], failures: [] };
+const sleep = ms => new Promise(resolve => setTimeout(resolve, ms));
+async function poll(fn, timeout = 90000) { const end = Date.now() + timeout; while (Date.now() < end) { if (await fn()) return true; await sleep(100); } return false; }
+
+async function run(engine) {
+  const cwd = join(scratch, engine); mkdirSync(cwd); cpSync(join(repo, 'frontend'), join(cwd, 'public'), { recursive: true }); mkdirSync(join(cwd, 'media'));
+  const portProbe = createServer(); await new Promise(resolve => portProbe.listen(0, '127.0.0.1', resolve)); const port = portProbe.address().port; await new Promise(resolve => portProbe.close(resolve));
+  let child, browser, proxy, context, log = '';
+  let origin = `http://127.0.0.1:${port}`;
+  const result = { engine, errors: [], failures: [], rms: [], checks: [] }; results.results.push(result);
+  async function stop() { if (!child) return; const proc = child; child = null; if (proc.exitCode === null) { proc.kill('SIGTERM'); await new Promise(resolve => proc.once('exit', resolve)); } }
+  try {
+    const clips = [
+      { id: 'dspfixture01', title: 'DSP test tone 110 Hz', channel: 'Local test', duration: 5, thumbnail: 'data:image/gif;base64,R0lGODlhAQABAAD/ACwAAAAAAQABAAACADs=' },
+      { id: 'dspfixture02', title: 'DSP test tone 660 Hz', channel: 'Local test', duration: 5, thumbnail: 'data:image/gif;base64,R0lGODlhAQABAAD/ACwAAAAAAQABAAACADs=' },
+    ];
+    child = spawn('bun', [join(repo, 'server/server.js')], { cwd, env: { ...process.env, PORT: String(port), DB_PATH: join(cwd, 'db.sqlite'), MEDIA_DIR: join(cwd, 'media'), UPLOAD_DIR: join(cwd, 'uploads'), DATA_DIR: join(cwd, 'data'), ASSET_HASHING: '1', ASSET_SYNC: '1', BUILD_TAG: '' }, stdio: ['ignore', 'pipe', 'pipe'] });
+    for (const stream of [child.stdout, child.stderr]) stream.on('data', chunk => { log = (log + chunk).slice(-8000); });
+    if (!await poll(async () => { if (child.exitCode !== null) throw Error(log); try { return (await fetch(origin + '/api/version')).ok; } catch { return false; } })) throw Error('Server did not start: ' + log);
+    for (const [index, clip] of clips.entries()) {
+      const mp4 = join(cwd, 'media', clip.id + '.1.mp4');
+      execFileSync('ffmpeg', ['-y', '-f', 'lavfi', '-i', 'color=c=blue:s=160x90:r=10:d=5', '-f', 'lavfi', '-i', `sine=frequency=${index ? 660 : 110}:duration=5`, '-c:v', 'libx264', '-pix_fmt', 'yuv420p', '-c:a', 'aac', '-movflags', '+faststart', '-shortest', mp4], { stdio: 'ignore' });
+      execFileSync('ffmpeg', ['-y', '-i', mp4, '-vn', '-c:a', 'copy', join(cwd, 'media', clip.id + '.1.m4a')], { stdio: 'ignore' });
+      assert.ok(existsSync(mp4), `generated local clip ${mp4}`);
+    }
+    const require = createRequire(import.meta.url); const { createClient } = require(join(repo, 'server/node_modules/@libsql/client'));
+    const db = createClient({ url: 'file:' + join(cwd, 'db.sqlite') });
+    for (const clip of clips) { const file = join(cwd, 'media', clip.id + '.1.mp4'); await db.execute({ sql: 'INSERT OR REPLACE INTO media_cache (video_id,status,gen,size,height,vcodec,acodec,duration,meta,last_access) VALUES (?,?,?,?,?,?,?,?,?,?)', args: [clip.id, 'ready', 1, statSync(file).size, 90, 'h264', 'aac', 5, JSON.stringify(clip), Date.now()] }); }
+    db.close();
+    proxy = createThrottleProxy({ targetPort: port, profile: 'unthrottled' }); origin = `http://127.0.0.1:${await proxy.listen()}`;
+    const type = engine === 'chromium' ? chromium : webkit; browser = await type.launch({ headless: true, ...(engine === 'chromium' ? { args: ['--autoplay-policy=no-user-gesture-required'] } : {}) });
+    context = await browser.newContext({ viewport: { width: 414, height: 896 } });
+    await context.addInitScript(() => { window.__dspToasts = []; new MutationObserver(() => { const text = document.querySelector('#toastContainer')?.textContent?.trim(); if (text && window.__dspToasts.at(-1) !== text) window.__dspToasts.push(text); }).observe(document, { childList: true, subtree: true, characterData: true }); });
+    await context.route('**/*', route => route.request().url().startsWith(origin) ? route.continue() : route.fulfill({ status: 200, contentType: 'image/gif', body: Buffer.from('R0lGODlhAQABAAD/ACwAAAAAAQABAAACADs=', 'base64') }));
+    const page = await context.newPage(); let offlinePhase = false, failedApiTransports = 0; page.on('pageerror', error => { if (offlinePhase && failedApiTransports && /TypeError: Load failed|\/api\//.test(error.message)) (result.expectedApiErrors ||= []).push(error.message); else result.errors.push(error.message); });
+    page.on('requestfailed', request => { const path = new URL(request.url()).pathname; if (path.startsWith('/api/')) failedApiTransports++; else if (!(offlinePhase && path === '/sw.js')) result.errors.push(`request failed ${request.url()}: ${request.failure()?.errorText}`); });
+    page.on('response', response => {
+      const url = new URL(response.url()), path = url.pathname;
+      // The local fixture IDs have no upstream YouTube artwork. These requests
+      // are unrelated to the local media or DSP asset path under test.
+      if (url.hostname === 'i.ytimg.com' && /\/vi\/dspfixture0[12]\//.test(path)) {
+        (result.fixtureResponses ||= []).push({ url: response.url(), status: response.status() });
+      } else if (!path.startsWith('/api/') && response.status() >= 400) result.errors.push(`asset response ${response.status()} ${response.url()}`);
+    });
+    page.on('response', response => { if (/jamesdsp\/(?:worklet\.mjs|dsp\/jamesdsp[^/?]*\.mjs)/.test(response.url())) result.requests ||= [], result.requests.push({ url: response.url(), status: response.status(), type: response.headers()['content-type'] }); });
+    page.on('requestfailed', request => { if (/jamesdsp\//.test(request.url())) result.requestsFailed ||= [], result.requestsFailed.push({ url: request.url(), error: request.failure()?.errorText }); });
+    const boot = async () => { await page.goto(origin); await page.waitForFunction(() => typeof data !== 'undefined' && document.querySelector('#sidebarToggle')); };
+    await boot();
+    const manifest = await (await fetch(origin + '/api/manifest')).json();
+    const checkComplete = () => page.evaluate(async ({ files, groups }) => { const cache = await caches.open('ytplayer-assets'), opted = !!(data.settings.jamesDsp?.enabled || data.settings.jamesDsp?.downloadForOffline); const optional = new Set(Object.values(groups).filter(group => group.offlineOptIn && !(opted && group.offlineOptIn === 'jamesDsp')).flatMap(group => group.files)); const missing = []; for (const [path, file] of Object.entries(files)) { if (optional.has(path)) continue; const r = await cache.match(path + '?v=' + file.h); if (!r || r.headers.get('X-Asset-Hash') !== file.h) missing.push(path); } return missing; }, manifest);
+    assert.equal((await page.evaluate(async () => { const shell = await caches.open('ytplayer-shell'); return (await shell.keys()).some(r => r.url.includes('jamesdsp')); })), false, 'DSP is never in the shell cache');
+    assert.equal(await poll(async () => !(await checkComplete()).length, 120000), true, 'offline completion job fills manifest before offline test');
+    const optionalCount = Object.values(manifest.groups || {}).filter(group => group.offlineOptIn).reduce((n, group) => n + group.files.filter(path => manifest.files[path]).length, 0);
+    result.checks.push({ name: 'required files cached; optional DSP deferred', files: Object.keys(manifest.files).length - optionalCount, optionalDeferred: optionalCount, manifestFiles: Object.keys(manifest.files).length });
+    await page.evaluate(async () => { await Lazy.load('feature:eq-core'); await Lazy.load('feature:vocal-reducer'); data.settings.jamesDsp = { enabled: false, downloadForOffline: false, preset: 'flat', params: {}, irRef: null }; EQ.setLevel(1); EQ.setLevel(0); EQ.apply(); });
+    await page.evaluate(clip => Player.loadVideo(clip), clips[0]);
+    await page.locator('#playBtn').click({ force: true }).catch(() => {});
+    if (!await poll(() => page.evaluate(() => Player.master?.currentTime > 0.4), 12000)) { await page.evaluate(() => Player.master?.play().catch(() => {})); assert.equal(await poll(() => page.evaluate(() => Player.master?.currentTime > 0.4), 12000), true, 'local test clip starts'); }
+    await page.evaluate(() => { if (Player.master) Player.master.loop = true; });
+    const rms = async () => page.evaluate(async () => {
+      const analyser = EQ.analyser(); if (!analyser) throw new Error('EQ analyser unavailable');
+      const values = new Float32Array(analyser.fftSize); let sum = 0, count = 0, end = performance.now() + 600;
+      while (performance.now() < end) { analyser.getFloatTimeDomainData(values); for (const v of values) { sum += v * v; count++; } await new Promise(resolve => setTimeout(resolve, 18)); }
+      return Math.sqrt(sum / Math.max(1, count));
+    });
+    await page.evaluate(() => { EQ.apply(); }); await sleep(250);
+    const standardRms = await rms(); assert.ok(standardRms > 0, `Standard output has nonzero RMS (${standardRms})`);
+    await page.locator('#bottomNav [data-view="settings"]').click(); await page.evaluate(() => document.querySelector('[data-section="playback"]').click());
+    await page.selectOption('#setSoundEngine', 'jamesdsp');
+    const active = await poll(() => page.evaluate(() => !!EQ.state().jamesDsp?.active), 12000);
+    if (!active) result.diagnostics = await page.evaluate(() => ({ enabled: data.settings.jamesDsp?.enabled, state: EQ.state(), lazyLoaded: Lazy.loaded('feature:jamesdsp'), toast: document.querySelector('#toastContainer')?.textContent || '', toastHistory: window.__dspToasts }));
+    assert.equal(active, true, `JamesDSP worklet activates ${JSON.stringify(result.diagnostics || {})}`);
+    assert.equal(await poll(async () => !(await checkComplete()).length, 120000), true, 'engine opt-in completes optional WASM and module cache');
+    await sleep(200); const flat = await rms(); result.rms.push({ effect: 'flat', rms: flat });
+    for (const preset of ['bass', 'vocal', 'loudness', 'headphone', 'bright', 'warm']) {
+      await page.selectOption('#setDspPreset', preset); await sleep(900);
+      const value = await rms(); assert.ok(Number.isFinite(value), `${preset} RMS is finite`); result.rms.push({ effect: preset, rms: value });
+    }
+    const preConvolverRms = await rms();
+    result.irLoad = await page.evaluate(async () => { const reference = await EQ.loadDspBuiltinIR('Small room'); await new Promise(resolve => setTimeout(resolve, 300)); return { reference, settings: data.settings.jamesDsp, state: EQ.state().jamesDsp, toast: document.querySelector('#toastContainer')?.textContent || '' }; });
+    const convolverRms = await rms();
+    assert.equal(result.irLoad.state.irRef?.name, 'Small room', 'generated IR is loaded into the active worklet');
+    result.checks.push({ name: 'live generated IR loaded', beforeRms: preConvolverRms, afterRms: convolverRms, ir: result.irLoad.state.irRef });
+    await page.evaluate(clip => { Player.pause(); Player.loadVideo(clip); }, clips[1]); await sleep(500); await page.evaluate(() => Player.master?.play().catch(() => {}));
+    const trackSwapActive = await poll(() => page.evaluate(() => Player.master?.currentSrc.includes('dspfixture02') && Player.master?.readyState >= 2 && EQ.state().jamesDsp?.active), 12000);
+    if (!trackSwapActive) result.trackSwapDiagnostics = await page.evaluate(() => ({ time: Player.master?.currentTime, paused: Player.master?.paused, readyState: Player.master?.readyState, state: EQ.state().jamesDsp, graph: AudioGraph.snapshot(), source: Player.master?.currentSrc }));
+    assert.equal(trackSwapActive, true, 'DSP remains active on the replacement media source');
+    result.checks.push({ name: 'track switch retains DSP route', graph: await page.evaluate(() => AudioGraph.snapshot()) });
+    await page.evaluate(() => { data.settings.jamesDsp.params['bass.enabled'] = 1; data.settings.jamesDsp.params['eq.enabled'] = 1; EQ.apply(); }); await sleep(800);
+    const activeRms = await rms();
+    await page.evaluate(async () => { await EQ.toggleDspBypass(); }); await sleep(200); const bypassRms = await rms();
+    const bypassState = await page.evaluate(() => EQ.state().jamesDsp);
+    assert.equal(bypassState.route, 'standard', 'A/B bypass routes directly to the unchanged Standard graph');
+    result.checks.push({ name: 'A/B exact Standard route', standardRms, activeRms, bypassRms, ...bypassState });
+    await page.evaluate(async () => { const state = EQ.state().jamesDsp, graph = AudioGraph.snapshot(); return { state, graph }; }).then(({ state, graph }) => {
+      assert.equal(state.liveHeaps, 1); assert.equal(state.maxLiveHeaps, 1); assert.ok(graph.sourceCount <= 2, 'only existing player media sources'); result.checks.push({ name: 'one worklet heap / single graph', ...state, graph });
+    });
+    const dspRender = await page.evaluate(async () => {
+      const { JamesDSPNode } = await import(Lazy.url('/vendor/jamesdsp/jamesdsp-node.mjs'));
+      async function render(effect, rate = 32000) {
+        const frames = 32768, context = new OfflineAudioContext(2, frames, rate);
+        const engine = await JamesDSPNode.create(context, { wasmURL: Lazy.url('/vendor/jamesdsp/dsp/jamesdsp.wasm'), workletURL: Lazy.url('/vendor/jamesdsp/worklet.mjs') });
+        const buffer = context.createBuffer(2, 2048, rate);
+        for (let i = 0; i < buffer.length; i++) { const sample = Math.sin(2 * Math.PI * 440 * i / rate) * 0.25; buffer.getChannelData(0)[i] = sample; buffer.getChannelData(1)[i] = sample; }
+        if (effect === 'convolver') {
+          const ir = context.createBuffer(4, 4096, rate); ir.getChannelData(0)[0] = 0.5; ir.getChannelData(1)[97] = 0.25; ir.getChannelData(2)[211] = -0.2; ir.getChannelData(3)[0] = 0.5;
+          await engine.loadIR(ir); await engine.setParam('convolver.mix', 1); await engine.setParam('convolver.enabled', 1);
+        } else if (effect === 'spatial') {
+          await engine.setParam('spatial.enabled', 1); await engine.setParam('spatial.mode', 6); await engine.setParam('spatial.spread', 100); await engine.setParam('spatial.azimuth', 45);
+        }
+        await engine.setBypass(false);
+        const source = context.createBufferSource(); source.buffer = buffer; source.connect(engine.node); engine.node.connect(context.destination); source.start();
+        const rendered = await context.startRendering();
+        const left = rendered.getChannelData(0), right = rendered.getChannelData(1);
+        let l = 0, r = 0, diff = 0; for (let i = 0; i < frames; i++) { l += left[i] ** 2; r += right[i] ** 2; diff += (left[i] - right[i]) ** 2; }
+        const metrics = { leftRms: Math.sqrt(l / frames), rightRms: Math.sqrt(r / frames), interauralRms: Math.sqrt(diff / frames), rate: rendered.sampleRate };
+        engine.destroy(); return metrics;
+      }
+      const dry = await render('dry'), convolver = await render('convolver'), spatial = await render('spatial');
+      return { dry, convolver, spatial };
+    });
+    assert.equal(dspRender.dry.rate, 32000, 'ASRC accepts an arbitrary AudioContext rate');
+    assert.ok(dspRender.convolver.interauralRms > dspRender.dry.interauralRms + 0.00001, `four-channel IR changes rendered stereo output (${JSON.stringify(dspRender)})`);
+    assert.ok(dspRender.spatial.interauralRms > dspRender.dry.interauralRms + 0.00001, `3D stage changes interaural difference (${JSON.stringify(dspRender)})`);
+    result.checks.push({ name: 'offline four-channel convolver, spatial difference and 32 kHz ASRC', ...dspRender });
+
+    await page.evaluate(() => persist()); await sleep(500);
+    offlinePhase = true; if (engine === 'chromium') await context.setOffline(true); else await proxy.setOffline(true);
+    await page.reload(); await page.waitForFunction(() => typeof data !== 'undefined' && document.querySelector('#sidebarToggle'));
+    assert.equal(await poll(() => page.evaluate(() => !!EQ.state().jamesDsp?.active), 30000), true, 'offline reload restores enabled DSP from cached modules');
+    assert.equal(await page.evaluate(() => EQ.state().jamesDsp?.irRef?.name), 'Small room', 'stored generated IR is restored offline');
+    result.checks.push({ name: 'offline reload with engine and stored IR enabled', missing: await checkComplete(), ir: await page.evaluate(() => EQ.state().jamesDsp?.irRef) });
+
+    // A separate fresh profile corrupts the optional wasm response and verifies that Standard stays audible.
+    offlinePhase = false; failedApiTransports = 0; if (engine === 'chromium') await context.setOffline(false); else await proxy.setOffline(false);
+    const brokenContext = await browser.newContext({ viewport: { width: 414, height: 896 } });
+    await brokenContext.route('**/*', route => route.request().url().startsWith(origin) ? route.continue() : route.fulfill({ status: 200, contentType: 'image/gif', body: Buffer.from('R0lGODlhAQABAAD/ACwAAAAAAQABAAACADs=', 'base64') }));
+    await brokenContext.addInitScript(() => { const realFetch = window.fetch.bind(window); window.fetch = (input, init) => String(input).includes('/vendor/jamesdsp/dsp/jamesdsp.wasm') ? Promise.resolve(new Response('corrupt', { status: 503 })) : realFetch(input, init); });
+    const brokenPage = await brokenContext.newPage(); brokenPage.on('pageerror', e => result.errors.push('corrupt test: ' + e.message)); await brokenPage.goto(origin); await brokenPage.waitForFunction(() => typeof data !== 'undefined');
+    await brokenPage.locator('#bottomNav [data-view="settings"]').click(); await brokenPage.evaluate(() => document.querySelector('[data-section="playback"]').click()); await brokenPage.selectOption('#setSoundEngine', 'jamesdsp');
+    assert.equal(await poll(() => brokenPage.evaluate(() => data.settings.jamesDsp.enabled === false && EQ.state().wired), 30000), true, 'corrupt wasm falls back to Standard');
+    result.checks.push({ name: 'corrupt wasm returns to Standard', enabled: await brokenPage.evaluate(() => data.settings.jamesDsp.enabled), graph: await brokenPage.evaluate(() => AudioGraph.snapshot()) });
+    await brokenContext.close();
+  } catch (error) { result.failures.push(error.stack || error.message); }
+  finally { await context?.close(); await browser?.close(); await proxy?.close(); await stop(); }
+}
+
+try { for (const engine of requested === 'all' ? ['chromium', 'webkit'] : [requested]) await run(engine); }
+finally { writeFileSync(join(repo, 'perf/.tmp/dsp-results.json'), JSON.stringify(results, null, 2) + '\n'); rmSync(scratch, { recursive: true, force: true }); }
+if (results.failures.length || results.results.some(result => result.failures.length || result.errors.length)) process.exitCode = 1;
--- a/perf/lazy.mjs
+++ b/perf/lazy.mjs
@@ -42,7 +42,8 @@ async function run(name){
  console.log(name,'initial boot');await page.goto(origin);await page.waitForFunction(()=>typeof data!=='undefined'&&document.querySelector('#carModeBtn'));
  await wait(page,async()=>!!(await navigator.serviceWorker.getRegistration())?.active);
  await page.evaluate(()=>Lazy.warm());
-  await wait(page,async()=>{const c=await caches.open('ytplayer-assets'),r=await c.match('/__ytp_asset_state');if(!r)return false;const s=await r.json();return !(await Promise.all(Object.values(s.current.groups).flatMap(g=>g.files).map(async p=>!!await c.match(p+'?v='+s.current.files[p].h)))).includes(false);});
+  await wait(page,async()=>{const c=await caches.open('ytplayer-assets'),r=await c.match('/__ytp_asset_state');if(!r)return false;const s=await r.json(),files=Object.entries(s.current.groups).filter(([,g])=>!g.offlineOptIn).flatMap(([,g])=>g.files);return !(await Promise.all(files.map(async p=>!!await c.match(p+'?v='+s.current.files[p].h)))).includes(false);});
+  assert.equal(await page.evaluate(async()=>{const m=Lazy.manifest,path='/vendor/jamesdsp/dsp/jamesdsp.wasm',cache=await caches.open('ytplayer-assets');return !await cache.match(path+'?v='+m.files[path].h);}),true,'optional DSP WASM stays uncached on a default install');
  console.log(name,'warm complete');assert.equal(await page.evaluate(()=>Lazy.loaded('feature:car-mode')),false);
  assert.equal(await page.evaluate(()=>[...document.querySelectorAll('.stg-overlay,.deck-chips,.vol-pct,.mode-name,.stg-bot,.ch-badge,.upnext-clear,.list-sub,.p2p-strip,.sleep-status .sl-ic,.sleep-status .sl-sub,.mc-tune')].every(n=>getComputedStyle(n).display==='none')),true,'classic retains shared visibility defaults without loading Glass CSS');
  await checkCssOrder(page);
--- a/perf/offline-complete.mjs
+++ b/perf/offline-complete.mjs
@@ -37,13 +37,22 @@ async function run(engine){
  };
  let page=await context.newPage();attach(page);
  const boot=async()=>{await page.goto(origin);await page.waitForFunction(()=>typeof data!=='undefined'&&document.querySelector('[aria-label="Car mode"]'));};
-  const inventory=()=>page.evaluate(async({manifest,legacy})=>{
+  const inventory=(includeOptional=false)=>page.evaluate(async({manifest,legacy,includeOptional})=>{
   const names=await caches.keys(),cache=await caches.open(legacy?names.find(n=>n.startsWith('ytplayer-')&&!['ytplayer-assets','ytplayer-fonts','ytplayer-thumbs'].includes(n)):'ytplayer-assets');
-   const missing=[];for(const [path,file]of Object.entries(manifest.files)){const r=await cache.match(legacy?path:path+'?v='+file.h);if(!r||(!legacy&&r.headers.get('X-Asset-Hash')!==file.h))missing.push(path);}
-   return{total:Object.keys(manifest.files).length,missing};
-  },{manifest,legacy});
+   const optional=new Set(Object.values(manifest.groups||{}).filter(group=>group.offlineOptIn).flatMap(group=>group.files||[]));
+   const expected=Object.entries(manifest.files).filter(([path])=>legacy||includeOptional||!optional.has(path));
+   const missing=[];for(const [path,file]of expected){const r=await cache.match(legacy?path:path+'?v='+file.h);if(!r||(!legacy&&r.headers.get('X-Asset-Hash')!==file.h))missing.push(path);}
+   return{total:expected.length,manifestTotal:Object.keys(manifest.files).length,optionalExcluded:Object.keys(manifest.files).length-expected.length,missing};
+  },{manifest,legacy,includeOptional});
  const started=Date.now();console.log(engine,'install boot');await boot();console.log(engine,'waiting for worker activation');if(!await poll(()=>page.evaluate(async()=>!!(await navigator.serviceWorker.getRegistration())?.active),30000))throw Error('Worker did not activate: '+JSON.stringify(await page.evaluate(async()=>{const r=await navigator.serviceWorker.getRegistration();return {active:r?.active?.state,waiting:r?.waiting?.state,installing:r?.installing?.state,caches:await caches.keys(),keys:(await(await caches.open('ytplayer-assets')).keys()).map(r=>new URL(r.url).pathname)};})));await page.evaluate(()=>navigator.serviceWorker.ready);console.log(engine,'worker active');await page.evaluate(()=>window.Lazy?.warm());
  await poll(async()=>!(await inventory()).missing.length,Number(option('--warm-timeout','15000')));
+  if(!legacy){const wasmPath='/vendor/jamesdsp/dsp/jamesdsp.wasm',wasm=manifest.files[wasmPath];if(wasm){const cached=await page.evaluate(async key=>!!await(await caches.open('ytplayer-assets')).match(key),wasmPath+'?v='+wasm.h);if(cached)result.failures.push({kind:'opt-in-wasm-cached-by-default',path:wasmPath});}}
+  if(!legacy){
+   await page.evaluate(()=>{data.settings.jamesDsp={...data.settings.jamesDsp,downloadForOffline:true};persist();reportDspOfflineOptIn();});
+   const dspReady=await poll(async()=>{const inventoryNow=await inventory(true);return !inventoryNow.missing.length;},120000);
+   result.conditions.push({name:'explicit audio-effects offline opt-in completes optional assets',complete:dspReady});
+   if(!dspReady)result.failures.push({kind:'optional-dsp-completion',paths:(await inventory(true)).missing});
+  }
  console.log(engine,'inventory complete');result.installMs=Date.now()-started;result.inventory=await inventory();result.installWire=proxy.getStats();result.saveData=await page.evaluate(()=>navigator.connection?.saveData);
  if(result.inventory.missing.length)result.failures.push({kind:'incomplete',paths:result.inventory.missing});
  // Offline navigation always starts from a controlled document.
@@ -108,13 +117,17 @@ async function run(engine){
    await page.evaluate(async manifest=>{const c=await caches.open('ytplayer-assets');for(const path of Object.keys(manifest.files).filter(p=>manifest.files[p].g!=='core'))await c.delete(path+'?v='+manifest.files[path].h);navigator.serviceWorker.controller.postMessage({type:'COMPLETE_ASSETS'});},manifest);
    await poll(()=>page.evaluate(async()=>{const c=await caches.open('ytplayer-assets'),s=await(await c.match('/__ytp_asset_state')).json(),r=await c.match('/__ytp_completion/'+s.current.buildTag);return r&&(await r.json()).running;}),5000);
    await page.close();await other.close();await proxy.setOffline(false);
-    const withoutPage=await poll(async()=>{const {cacheDataEntries:entries}=await cdp.send('CacheStorage.requestEntries',{cacheId,skipCount:0,pageSize:1000});return Object.entries(manifest.files).every(([path,file])=>entries.some(e=>e.requestURL===origin+path+'?v='+file.h&&e.responseHeaders.some(h=>h.name.toLowerCase()==='x-asset-hash'&&h.value===file.h)));});
+    const optionalPaths=new Set(Object.values(manifest.groups||{}).filter(group=>group.offlineOptIn==='jamesDsp').flatMap(group=>group.files||[]));
+    const includeOptional=await page.evaluate(async()=>{const cache=await caches.open('ytplayer-assets'),response=await cache.match('/__ytp_offline_opt_ins');return (await response?.json()||[]).includes('jamesDsp');});
+    const requiredFiles=Object.entries(manifest.files).filter(([path])=>includeOptional||!optionalPaths.has(path));
+    const withoutPage=await poll(async()=>{const {cacheDataEntries:entries}=await cdp.send('CacheStorage.requestEntries',{cacheId,skipCount:0,pageSize:1000});return requiredFiles.every(([path,file])=>entries.some(e=>e.requestURL===origin+path+'?v='+file.h&&e.responseHeaders.some(h=>h.name.toLowerCase()==='x-asset-hash'&&h.value===file.h)));});
    result.conditions.push({name:'worker completes with every application page closed; passive same-origin inspector only',complete:withoutPage});
    if(!withoutPage)result.failures.push({kind:'completion-without-page'});
    await cdp.detach();await inspector.close();
   }else await other.close();
  }
-  console.log(engine,JSON.stringify({missing:result.inventory.missing,failures:result.failures,conditions:result.conditions}));
+  result.inventory=await inventory(!legacy);
+  console.log(engine,JSON.stringify({missing:result.inventory.missing,inventory:result.inventory.total,manifestFiles:result.inventory.manifestTotal,failures:result.failures,conditions:result.conditions}));
 }catch(e){result.failures.push({kind:'harness',error:e.stack});console.log(engine,e.message);}finally{await context?.close();await browser?.close();await proxy?.close();child.kill('SIGTERM');if(child.exitCode===null)await new Promise(r=>child.once('exit',r));}
 }
 try{for(const engine of option('--browser','all')==='all'?['chromium','webkit']:[option('--browser')])await run(engine);}finally{writeFileSync(resolve(option('--out',join(repo,'perf/results/offline-complete.json'))),JSON.stringify({results},null,2)+'\n');rmSync(scratch,{recursive:true,force:true});}
--- a/perf/results/dsp-cold-check.json
+++ b/perf/results/dsp-cold-check.json
--- a/perf/retry.mjs
+++ b/perf/retry.mjs
@@ -0,0 +1,108 @@
+#!/usr/bin/env node
+// Foreground transient-failure regression check over the real Bun server and
+// shaped local proxy. Injects one 503/connection drop, then requires recovery
+// without exposing the application's manual Retry/error affordances.
+import assert from 'node:assert/strict';
+import { spawn } from 'node:child_process';
+import { cpSync, mkdirSync, rmSync } from 'node:fs';
+import { join, resolve } from 'node:path';
+import { createServer } from 'node:net';
+import { chromium, webkit } from 'playwright';
+import { createThrottleProxy } from './proxy.mjs';
+
+const repo = resolve(new URL('..', import.meta.url).pathname);
+const scratch = join(repo, 'perf/.tmp/retry');
+const profile = process.argv.includes('--profile') ? process.argv[process.argv.indexOf('--profile') + 1] : 'lossy';
+const engines = process.argv.includes('--browser') ? process.argv[process.argv.indexOf('--browser') + 1] : 'all';
+assert.ok(['all', 'chromium', 'webkit'].includes(engines));
+rmSync(scratch, { recursive: true, force: true }); mkdirSync(scratch, { recursive: true });
+const results = [];
+const sleep = ms => new Promise(resolve => setTimeout(resolve, ms));
+async function freePort() { const s = createServer(); await new Promise(r => s.listen(0, '127.0.0.1', r)); const p = s.address().port; await new Promise(r => s.close(r)); return p; }
+async function poll(fn, timeout = 30000) { const end = Date.now() + timeout; while (Date.now() < end) { if (await fn()) return true; await sleep(100); } return false; }
+
+for (const engine of engines === 'all' ? ['chromium', 'webkit'] : [engines]) {
+  const cwd = join(scratch, engine); mkdirSync(cwd); cpSync(join(repo, 'frontend'), join(cwd, 'public'), { recursive: true });
+  const port = await freePort(); let log = '';
+  const child = spawn('bun', [join(repo, 'server/server.js')], { cwd, env: { ...process.env, PORT: String(port), ASSET_HASHING: '1', ASSET_SYNC: '1', BUILD_TAG: '', DB_PATH: join(cwd, 'db.sqlite'), DATA_DIR: join(cwd, 'data'), MEDIA_DIR: join(cwd, 'media'), UPLOAD_DIR: join(cwd, 'uploads') }, stdio: ['ignore', 'pipe', 'pipe'] });
+  for (const stream of [child.stdout, child.stderr]) stream.on('data', chunk => log = (log + chunk).slice(-8000));
+  let browser, context, proxy;
+  const result = { engine, profile, injected: [], recovered: [], visibleErrors: [] }; results.push(result);
+  try {
+    if (!await poll(async () => { try { return (await fetch(`http://127.0.0.1:${port}/api/version`)).ok; } catch { return false; } })) throw Error(`server failed: ${log}`);
+    proxy = createThrottleProxy({ targetPort: port, profile }); proxy.startTracking();
+    const origin = `http://127.0.0.1:${await proxy.listen()}`;
+    browser = await ({ chromium, webkit })[engine].launch({ headless: true });
+    context = await browser.newContext({ serviceWorkers: 'block' });
+    await context.route('**/*', route => route.request().url().startsWith(origin) ? route.continue() : route.abort());
+    const page = await context.newPage();
+    page.on('console', msg => { if (msg.type() === 'error') result.visibleErrors.push(msg.text()); });
+    page.on('pageerror', error => result.visibleErrors.push(error.message));
+
+    const searchUrl = '**/api/search?q=retry-transport-test*'; let searchCalls = 0;
+    await context.route(searchUrl, async route => {
+      searchCalls++; result.injected.push({ path: '/api/search', attempt: searchCalls, fault: searchCalls === 1 ? '503' : null });
+      if (searchCalls === 1) return route.fulfill({ status: 503, contentType: 'application/json', body: JSON.stringify({ error: 'temporary proxy fault' }) });
+      return route.fulfill({ contentType: 'application/json', body: JSON.stringify({ ok: true, results: [{ id: 'abcdefghijk', title: 'Retry fixture result', channel: 'Harness', duration: 60, thumbnail: '' }] }) });
+    });
+    await page.goto(origin);
+    await page.waitForFunction(() => typeof data !== 'undefined' && document.querySelector('#searchInput'));
+    let versionCalls = 0;
+    await context.route('**/api/version', async route => {
+      versionCalls++; result.injected.push({ path: '/api/version', attempt: versionCalls, fault: versionCalls === 1 ? '503' : null });
+      if (versionCalls === 1) return route.fulfill({ status: 503, contentType: 'application/json', body: JSON.stringify({ error: 'temporary version check failure' }) });
+      return route.fulfill({ contentType: 'application/json', body: JSON.stringify({ buildTag: 'retry-harness' }) });
+    });
+    assert.equal(await page.evaluate(() => fetchServerBuild()), 'retry-harness');
+    assert.equal(versionCalls, 2, `${engine}: update version check did not retry`);
+    result.recovered.push({ path: '/api/version', attempts: versionCalls });
+
+    await page.locator('#searchInput').fill('retry-transport-test'); await page.locator('#searchForm').evaluate(form => form.requestSubmit());
+    await page.locator('.card').filter({ hasText: 'Retry fixture result' }).waitFor({ timeout: 25000 });
+    result.recovered.push({ path: '/api/search', attempts: searchCalls });
+    assert.equal(searchCalls, 2, `${engine}: search did not retry exactly once`);
+    assert.equal(await page.locator('.retry-btn,.related-retry').count(), 0, `${engine}: transient search exposed a manual retry`);
+
+    let streamCalls = 0;
+    await context.route('**/api/streams?v=abcdefghijk*', async route => {
+      streamCalls++; result.injected.push({ path: '/api/streams', attempt: streamCalls, fault: streamCalls === 1 ? '503' : null });
+      if (streamCalls === 1) return route.fulfill({ status: 503, contentType: 'application/json', body: JSON.stringify({ error: 'temporary upstream failure' }) });
+      return route.fulfill({ contentType: 'application/json', body: JSON.stringify({ ok: true, data: { meta: { id: 'abcdefghijk', title: 'Stream fixture' }, qualities: [] } }) });
+    });
+    const streams = await page.evaluate(() => API.getStreams('abcdefghijk'));
+    assert.equal(streamCalls, 2, `${engine}: stream lookup did not retry`);
+    assert.equal(streams.ok, true);
+    result.recovered.push({ path: '/api/streams', attempts: streamCalls });
+
+    let relatedCalls = 0;
+    await context.route('**/api/related?*', async route => {
+      relatedCalls++; result.injected.push({ path: '/api/related', attempt: relatedCalls, fault: relatedCalls === 1 ? 'connection-reset' : null });
+      if (relatedCalls === 1) return route.abort('failed');
+      return route.fulfill({ contentType: 'application/json', body: JSON.stringify({ ok: true, results: [{ id: 'lmnopqrstuv', title: 'Related recovered', channel: 'Harness' }] }) });
+    });
+    const relatedState = await page.evaluate(async () => {
+      current = { meta: { id: 'abcdefghijk', title: 'Retry fixture result', channel: 'Harness' } };
+      await loadRelated(); return relatedState.status;
+    });
+    assert.equal(relatedCalls, 2, `${engine}: related discovery did not retry`);
+    assert.equal(relatedState, 'ready');
+    assert.equal(await page.locator('.related-retry').count(), 0, 'transient failure must not expose manual Retry');
+    result.recovered.push({ path: '/api/related', attempts: relatedCalls });
+
+    let chunkCalls = 0;
+    await context.route('**/video-edit.js?v=*', async route => {
+      chunkCalls++; result.injected.push({ path: '/video-edit.js', attempt: chunkCalls, fault: chunkCalls === 1 ? 'connection-reset' : null });
+      if (chunkCalls === 1) return route.abort('failed');
+      return route.continue();
+    });
+    await page.evaluate(() => Lazy.load('feature:video-edit'));
+    assert.equal(chunkCalls, 2, `${engine}: lazy chunk did not retry`);
+    assert.equal(await page.locator('.retry-btn,.related-retry').count(), 0);
+    result.recovered.push({ path: '/video-edit.js', attempts: chunkCalls });
+    const unexpected = result.visibleErrors.filter(message => !/Failed to load resource|Load failed/.test(message));
+    assert.deepEqual(unexpected, [], `${engine}: page errors after transient recovery`);
+    console.log(JSON.stringify(result));
+  } catch (error) { console.error(engine, log); throw error; }
+  finally { await context?.close(); await browser?.close(); await proxy?.close?.(); child.kill('SIGTERM'); }
+}
+console.log(`Retry recovery passed (${results.length} engine(s), ${profile}).`);
--- a/perf/settings-layout.mjs
+++ b/perf/settings-layout.mjs
@@ -0,0 +1,84 @@
+#!/usr/bin/env node
+// Settings layout regression checks across responsive widths, layouts and themes.
+import assert from 'node:assert/strict';
+import { createServer } from 'node:http';
+import { readFile, mkdir } from 'node:fs/promises';
+import { resolve, extname } from 'node:path';
+import { chromium, webkit } from 'playwright';
+
+const root = resolve('frontend'), shots = resolve('plans/settings-shots');
+await mkdir(shots, { recursive: true });
+const mime = { '.html':'text/html', '.js':'text/javascript', '.mjs':'text/javascript', '.css':'text/css', '.json':'application/json', '.woff2':'font/woff2', '.svg':'image/svg+xml', '.png':'image/png' };
+const server = createServer(async (req, res) => {
+  const url = new URL(req.url, 'http://localhost');
+  const path = resolve(root, '.' + (url.pathname === '/' ? '/index.html' : url.pathname));
+  if (!path.startsWith(root + '/')) { res.writeHead(403).end(); return; }
+  try { const body = await readFile(path); res.writeHead(200, { 'Content-Type':mime[extname(path)] || 'application/octet-stream' }).end(body); }
+  catch { res.writeHead(404).end(); }
+});
+await new Promise(r => server.listen(0, '127.0.0.1', r));
+const origin = `http://127.0.0.1:${server.address().port}`;
+const layouts = ['classic','f7-swipe','glass-stage','bento-hub'], themes = ['dark','light','contrast'], widths = [390,768,1280,1440,1920];
+const failures = [], results = [];
+try {
+  for (const [engineName, engine] of Object.entries({ chromium, webkit })) {
+    const browser = await engine.launch();
+    try {
+      const context = await browser.newContext({ viewport:{width:1280,height:1000}, serviceWorkers:'block' });
+      await context.route('**/*', route => route.request().url().startsWith(origin) ? route.continue() : route.abort());
+      await context.addInitScript(() => localStorage.setItem('_ytpdata', JSON.stringify({
+        playlists:[], history:[], queue:[], settings:{layout:'glass-stage',theme:'dark',quality:'auto',jamesDsp:{enabled:true,downloadForOffline:false,preset:'warm',params:{'convolver.enabled':1,'spatial.enabled':1},irRef:{name:'Small room'}}}
+      })));
+      const page = await context.newPage();
+      page.on('pageerror', error => failures.push(`${engineName}: pageerror ${error.message}`));
+      await page.goto(origin);
+      await page.waitForFunction(() => typeof data !== 'undefined' && typeof Lazy !== 'undefined');
+      await page.waitForFunction(() => performance.getEntriesByName('ytp:boot').length > 0);
+      for (const css of ['theme-classic.css','theme-f7.css','theme-glass.css','theme-glass-panel.css','theme-glass-controls.css','theme-bento-hub.css']) await page.addStyleTag({ path:resolve(root,css) });
+      for (const layout of layouts) {
+        for (const theme of themes) for (const width of widths) {
+          await page.setViewportSize({ width, height:1000 });
+          await page.evaluate(({theme,layout}) => { data.settings.theme=theme; data.settings.layout=layout; data.settings.jamesDsp.enabled=true; document.documentElement.dataset.theme=theme; document.documentElement.dataset.layout=layout; if(typeof EQ!=='undefined')EQ.listDspIRs=async()=>[]; view={type:'settings'}; render(); }, {theme,layout});
+          await page.waitForSelector('.settings-browser .settings-section-row[data-section="playback"]',{state:'attached'});
+          await page.evaluate(()=>{const host=document.querySelector('.settings-browser');host.dataset.detail='1';document.querySelectorAll('.settings-section').forEach(panel=>panel.hidden=panel.id!=='settings-section-playback');document.getElementById('jamesDspControls').hidden=false;});
+          await page.waitForSelector('#setDspSpatialMode',{state:'attached'});
+          const measured = await page.evaluate(() => {
+            const rect = e => { const r=e.getBoundingClientRect(); return {x:r.x,y:r.y,width:r.width,height:r.height,right:r.right}; };
+            const selectors=['.settings-browser','.settings-grid','.settings-detail','#listPane .cards','#jamesDspSettings','.dsp-subsection'];
+            const boxes=Object.fromEntries(selectors.map(s=>{const e=document.querySelector(s);return [s,e?{clientWidth:e.clientWidth,scrollWidth:e.scrollWidth,rect:rect(e)}:null];}));
+            const rows=[...document.querySelectorAll('#jamesDspSettings .set-row')].map(row=>{
+              const label=row.querySelector(':scope > span:first-child'),control=row.querySelector(':scope > input,:scope > select,:scope > .set-control-wrap,:scope > .dsp-file-control');
+              return {text:row.textContent.trim().slice(0,90),label:label?rect(label):null,control:control?{...rect(control),scrollWidth:control.scrollWidth,clientWidth:control.clientWidth,overflow:getComputedStyle(control).overflow,select:control.querySelector('select')?{...rect(control.querySelector('select')),scrollWidth:control.querySelector('select').scrollWidth,clientWidth:control.querySelector('select').clientWidth}:null}:null,row:rect(row)};
+            });
+            const file=document.querySelector('#dspIrFile'),checkbox=document.querySelector('#setDspConvolver'),buttons=[...document.querySelectorAll('.dsp-subsection > button')];
+            const selects=[...document.querySelectorAll('.settings-browser select')].map(s=>({id:s.id,appearance:getComputedStyle(s).appearance,backgroundImage:getComputedStyle(s).backgroundImage,backgroundColor:getComputedStyle(s).backgroundColor}));
+            const overflows=[...document.querySelectorAll('#jamesDspSettings *')].filter(e=>e.scrollWidth>e.clientWidth+1).map(e=>({tag:e.tagName,id:e.id,cls:e.className,text:e.textContent.trim().slice(0,100),scroll:e.scrollWidth,client:e.clientWidth,rect:rect(e)}));
+            return {boxes,rows,file:{clipPath:getComputedStyle(file).clipPath,rect:rect(file),parent:rect(file.parentElement)},checkbox:{appearance:getComputedStyle(checkbox).appearance,width:rect(checkbox).width},selects,buttons:buttons.map(b=>({whiteSpace:getComputedStyle(b).whiteSpace,scrollWidth:b.scrollWidth,clientWidth:b.clientWidth,rect:rect(b)})),overflows,page:{scrollWidth:document.documentElement.scrollWidth,clientWidth:document.documentElement.clientWidth}};
+          });
+          const key=`${engineName}/${layout}/${theme}/${width}`;
+          for (const [selector,box] of Object.entries(measured.boxes)) if(box) {
+            if(box.scrollWidth>box.clientWidth+1) failures.push(`${key}: ${selector} horizontal overflow ${box.scrollWidth}/${box.clientWidth}`);
+          }
+          if(measured.page.scrollWidth>measured.page.clientWidth+1) failures.push(`${key}: document horizontal overflow ${measured.page.scrollWidth}/${measured.page.clientWidth}`);
+          for(const row of measured.rows) if(row.label&&row.control&&row.control.x<row.label.x+Math.min(row.label.width,80)) failures.push(`${key}: control overlaps/collapses into label`);
+          if(measured.checkbox.appearance!=='none'||measured.checkbox.width<40) failures.push(`${key}: DSP checkbox is not a themed switch`);
+          for(const select of measured.selects) if(select.appearance!=='none'||select.backgroundImage==='none'||select.backgroundColor==='rgba(0, 0, 0, 0)') failures.push(`${key}: select #${select.id} is not themed`);
+          if(measured.file.rect.width>1||measured.file.clipPath==='none') failures.push(`${key}: native file picker is visible`);
+          for(const b of measured.buttons) if(b.whiteSpace!=='nowrap'||b.rect.height>50) failures.push(`${key}: DSP action button wraps vertically`);
+          results.push({engine:engineName,layout,theme,width,...measured});
+          if(width===1280) await page.screenshot({path:resolve(shots,`${engineName}-${layout}-${theme}.png`),fullPage:true});
+          if(width===1280&&layout==='glass-stage'&&theme==='dark') {
+            await page.locator('#dspConvolverTitle').scrollIntoViewIfNeeded();
+            await page.screenshot({path:resolve(shots,`${engineName}-glass-stage-dark-dsp.png`),fullPage:true});
+            await page.locator('#dspSpatialTitle').scrollIntoViewIfNeeded();
+            await page.screenshot({path:resolve(shots,`${engineName}-glass-stage-dark-spatial.png`),fullPage:true});
+          }
+        }
+      }
+      await context.close();
+    } finally { await browser.close(); }
+  }
+} finally { await new Promise(r=>server.close(r)); }
+await (await import('node:fs/promises')).writeFile(resolve(shots,'measurements.json'),JSON.stringify({cases:results.length,failures,screenshots:results.filter(r=>r.width===1280).map(r=>`${r.engine}-${r.layout}-${r.theme}.png`)},null,2));
+console.log(`Settings layout: ${results.length} cases, ${failures.length} failures; screenshots in plans/settings-shots/`);
+if(failures.length) { console.error(failures.slice(0,30).join('\n')); process.exitCode=1; }
--- a/perf/settings-persist.mjs
+++ b/perf/settings-persist.mjs
@@ -10,7 +10,7 @@ import {createRequire} from 'node:module';
 import {chromium,webkit} from 'playwright';
 const repo=resolve(import.meta.dirname,'..'),args=process.argv.slice(2);
 const opt=(k,d)=>args.includes(k)?args[args.indexOf(k)+1]:d;
-const oldTag='1175f1a1d2c1',target=opt('--target','main'),engine=opt('--browser','all');
+const oldTag='1175f1a1d2c1',target=opt('--target','HEAD'),engine=opt('--browser','all');
 assert.ok(['all','chromium','webkit'].includes(engine));
 execFileSync('bash',[join(repo,'perf/make-shell-fixture.sh'),'b77938a',oldTag],{cwd:repo,stdio:'inherit'});
 const scratch=mkdtempSync(join(repo,'perf/.tmp/settings-'));
@@ -21,7 +21,7 @@ symlinkSync(join(repo,'perf/fixtures/shell-'+oldTag),join(scratch,'old/server/pu
 symlinkSync(join(scratch,'new/frontend'),join(scratch,'new/server/public'));
 const results={revision,oldTag,results:[],failures:[],unsupported:[]};
 const sleep=ms=>new Promise(r=>setTimeout(r,ms));
-async function poll(fn,timeout=90000){const until=Date.now()+timeout;while(Date.now()<until){if(await fn())return;await sleep(100);}throw Error('Condition timed out');}
+async function poll(fn,timeout=90000){const until=Date.now()+timeout;while(Date.now()<until){if(await fn())return true;await sleep(100);}throw Error('Condition timed out');}
 const ui={saveBeforePlay:['setSaveBeforePlay',true],autoPreload:['setAutoPreload',true],audioOnly:['setAudioOnly',false],quality:['setQuality','360p'],repeatMode:['setRepeat',true],loopOne:['setLoopOne',true],theme:['setTheme','light'],fontScale:['setFont','large'],density:['setDensity','compact'],perfMode:['setPerf',true],reduceMotion:['setMotion',true],parallelSaves:['setParallelSaves','2'],levelVolume:['setLevelVolume',false],layout:['setLayout','f7-swipe']};
 async function run(name){
 const cwd=join(scratch,name);mkdirSync(cwd);mkdirSync(join(cwd,'media'));
@@ -49,7 +49,7 @@ async function run(name){
 await context.route('**/*',route=>route.request().url().startsWith(origin)?route.continue():route.abort());
 const page=await context.newPage();page.on('pageerror',e=>result.errors.push(e.message));
 const boot=async()=>{await page.goto(origin);await page.waitForFunction(()=>typeof data!=='undefined'&&document.querySelector('#sidebarToggle'));await page.waitForTimeout(800);};
- const settings=()=>page.evaluate(()=>JSON.parse(localStorage.getItem('_ytpdata')).settings);
+ const settings=()=>page.evaluate(()=>JSON.parse(JSON.stringify(data.settings)));
 const openSettings=async()=>{await page.locator('[data-view="settings"]').first().evaluate(e=>e.click());await page.waitForSelector('#setSaveBeforePlay',{state:'attached'});};
 const readUI=()=>page.evaluate(ids=>Object.fromEntries(ids.map(id=>{const e=document.getElementById(id);return[id,e.type==='checkbox'?e.checked:e.value];})),Object.values(ui).map(x=>x[0]));
 await boot();await page.waitForFunction(()=>!!navigator.serviceWorker.controller);
@@ -67,9 +67,16 @@ async function run(name){
 await page.waitForFunction(()=>!document.getElementById('modal').classList.contains('hidden')&&/Update available/.test(document.getElementById('modalTitle').textContent));
 await page.locator('#modal').getByRole('button',{name:'Refresh UI',exact:true}).evaluate(e=>e.click());await page.waitForFunction(tag=>document.querySelector('meta[name="ytp-build"]')?.content===tag,result.newTag,{timeout:90000});await sleep(1000);await openSettings();
 console.log(name,'real Refresh UI completed');result.upgraded=await settings();result.newRaw=await page.evaluate(()=>localStorage.getItem('_ytpdata'));result.newUI=await readUI();assert.deepEqual(result.newUI,result.oldUI,'checkbox/select values preserved');
- const {migrate}=require(join(scratch,'new/frontend/eq-parameters.js'));const expected=structuredClone(result.old);if(expected.eq?.g?.length===5)expected.eq.g=migrate(expected.eq.g);
- for(const key of new Set([...Object.keys(result.old),...Object.keys(result.upgraded)]))result.diff.push({key,before:result.old[key],after:result.upgraded[key],equal:JSON.stringify(result.old[key])===JSON.stringify(result.upgraded[key]),expectedMigration:key==='eq'&&result.old.eq?.g?.length===5});
+ const {migrate}=require(join(scratch,'new/frontend/eq-parameters.js'));const expected=structuredClone(result.old);if(expected.eq?.g?.length===5)expected.eq.g=migrate(expected.eq.g);expected.jamesDsp={enabled:false,downloadForOffline:false,preset:'flat',params:{},irRef:null,...(expected.jamesDsp||{}),params:expected.jamesDsp?.params||{}};
+ for(const key of new Set([...Object.keys(result.old),...Object.keys(result.upgraded)]))result.diff.push({key,before:result.old[key],after:result.upgraded[key],equal:JSON.stringify(result.old[key])===JSON.stringify(result.upgraded[key]),expectedMigration:(key==='eq'&&result.old.eq?.g?.length===5)||(key==='jamesDsp'&&!result.old.jamesDsp)});
 assert.deepEqual(result.upgraded,expected,'all persisted settings preserved except deliberate 5→10 EQ migration');await behaviour('upgraded');
+ await openSettings();await page.locator('[data-section="playback"]').evaluate(e=>e.click());await page.locator('#setDspPreset').evaluate(e=>{e.value='warm';e.dispatchEvent(new Event('change',{bubbles:true}));});
+ for(const [key,value] of [['eq.band0','3'],['tube.drive','1.5']])await page.locator(`[data-dsp-param="${key}"]`).evaluate((e,v)=>{e.value=v;e.dispatchEvent(new Event('input',{bubbles:true}));},value);
+ await sleep(600);await page.reload();await page.waitForFunction(()=>typeof data!=='undefined');await openSettings();await page.locator('[data-section="playback"]').evaluate(e=>e.click());
+ const james=await page.evaluate(()=>data.settings.jamesDsp);assert.deepEqual(james,{enabled:false,downloadForOffline:false,preset:'warm',params:{'eq.band0':3,'tube.drive':1.5},irRef:null});assert.equal(await page.locator('#setSoundEngine').inputValue(),'standard');assert.equal(await page.locator('#setDspPreset').inputValue(),'warm');
+ await page.locator('#setDspOffline').check();const wasmReady=await poll(()=>page.evaluate(async()=>{const m=JSON.parse(document.getElementById('ytp-assets').textContent),c=await caches.open('ytplayer-assets');return !!await c.match('/vendor/jamesdsp/dsp/jamesdsp.wasm?v='+m.files['/vendor/jamesdsp/dsp/jamesdsp.wasm'].h);}));assert.equal(wasmReady,true,'offline opt-in eventually caches the optional WASM');const optInPersisted=await poll(()=>page.evaluate(()=>JSON.parse(localStorage.getItem('_ytpdata')||'{}').settings?.jamesDsp?.downloadForOffline===true));assert.equal(optInPersisted,true,'offline opt-in setting survives local persistence debounce');
+ await page.reload();await page.waitForFunction(()=>typeof data!=='undefined');await openSettings();await page.locator('[data-section="playback"]').evaluate(e=>e.click());assert.equal(await page.locator('#setDspOffline').isChecked(),true);result.jamesDspSettingsPersisted=true;
+ await page.evaluate(()=>{data.settings.jamesDsp.enabled=false;persist();});
 const local=await settings(),remote={...local,saveBeforePlay:false,autoPreload:false,layout:'classic',quality:'auto'};
 async function profileCheck(updatedAt,expectedSave,stage){profileReply={ok:true,name:'probe',updatedAt,data:{settings:remote,playlists:[]}};await page.evaluate(s=>{data.settings=s;data.profile={name:'probe',syncedAt:200};localStorage.setItem('_ytpdata',JSON.stringify(data));},local);await boot();await page.waitForFunction(()=>_syncBusy===0);await openSettings();const s=await settings();assert.equal(s.saveBeforePlay,expectedSave);assert.equal(await page.locator('#setSaveBeforePlay').isChecked(),expectedSave);if(!expectedSave)assert.equal(s.layout,'classic');else assert.deepEqual(s,local);result.profileChecks.push({stage,serverUpdatedAt:updatedAt,localSyncedAt:200,saveBeforePlay:s.saveBeforePlay});}
 await profileCheck(100,true,'older timestamp ignored');await profileCheck(300,false,'older settings with newer timestamp adopted');
--- a/plans/jamesdsp-audit.md
+++ b/plans/jamesdsp-audit.md
@@ -0,0 +1,30 @@
+# JamesDSP integration audit
+
+Date: 2026-10-09  
+Base: `933e920` (`main`, Phase 0–5, offline completion, UI and transport integration)
+
+## Audio ownership found in the current runtime
+
+| Concern | Current owner / finding | Integration consequence |
+|---|---|---|
+| Realtime context | `EQ` in `frontend/app.js` is the only runtime constructor (`new AC()` around line 5532). | Preserve this exact lazy creation point. JamesDSP may not instantiate another context. |
+| Media element sources | `EQ.attach()` is the only runtime `createMediaElementSource()` call (around line 5559); it records sources by element in `st.sources`. | Extract this into one AudioGraph owner with a retained `WeakMap`/`Map`. Never retry creation for a previously attached media element. |
+| Playback elements | `Player.master`, `Player.secondary`, and `Player.soundEl` change between `els.video` and `els.audio` for dual/audio-only playback and handoffs. `EQ.apply()` attaches both video and audio elements. | Attach each element once; route both through the same selected insert. Do not tie graph lifetime to a track or to `Player.master`. |
+| Continuity and transitions | `audio-continuity.js` owns play/resume/alignment. `Transition` changes the active master and uses a bridge element; the bridge is not currently connected to EQ. | Keep continuity and bridge timing unchanged. A JamesDSP route applies to the same player elements as the Standard route; do not source the bridge or alter transition policy. |
+| iOS live processing | `EQ.available()` is false on iOS unless `data.settings.liveAudioIOS === true` (around line 5516). `EqRender` prepares saved audio with a 32 kHz `OfflineAudioContext`. | Gate live JamesDSP on the same setting and supported realtime graph. V1 does not process EqRender output; a DSP graph must never be layered over an already-rendered Standard EQ copy. |
+| Level / limiter | `Level` measures at 22.05 kHz offline and applies dB gain through `EQ.setLevel()`. The realtime Standard chain ends in a compressor limiter. | Preserve the Level measurement and dB value. In JamesDSP mode map it into the engine gain with a documented combined-gain clamp; Standard remains untouched. |
+| EqRender | `EqRender` renders cached media through an offline graph at 32 kHz and saves `eq-renders` OPFS copies. It is independent from the single realtime `AudioContext`. | Leave this renderer and its bytes unchanged. Until offline worklet rendering is proven, JamesDSP does not claim to process saved/rendered copies. |
+| VocalReducer / widener | Loaded lazily by `feature:vocal-reducer` and `feature:eq-core`, then connected in `EQ.build()`. | In JamesDSP mode disconnect the Standard insert. Do not create either lazy Standard effect solely to initialize JamesDSP. |
+| Cold path | `audio-continuity.js`, `eq-parameters.js`, and `app.js` are core assets. JamesDSP has no existing runtime assets. | Keep all new vendor/worklet/wasm/controller files exclusively in lazy `feature:jamesdsp`; the small graph owner may be core only if unavoidable, and its cost must be checked against integration cold-start medians. |
+
+## Seam and compatibility decisions
+
+Phase 2 will add a small `frontend/audio-graph.js` core seam because it gives the one-context/one-source invariant an independently testable owner. It will create the context only when the existing EQ asks for it, retain each element source for the page lifetime, and expose controlled Standard and optional JamesDSP route operations. It will not change playback, transition, or volume code. The new core request is a measured risk: compare cold FCP/bytes to `plans/integration-report.md` and inline the seam into an existing core module if it causes a regression.
+
+The Standard graph's node order, filter constants, gain automation, lazy-load triggers, and destination routing are a frozen compatibility contract. Phase 2 will add a graph trace test comparing the old route with the extracted route, plus deterministic sample-response tests for the Standard chain. JamesDSP activation is opt-in and serialized: restore Standard before destroying a failed node, never create a replacement until the previous 128 MiB node is destroyed, and reject the engine when the existing context rate is not 44.1 or 48 kHz. The existing context is never closed/recreated to request 48 kHz.
+
+The standalone port verifies 44.1/48 kHz, a fixed 128 MiB heap, immediate exact bypass, and configuration that can pause worklet rendering. It has no Safari/iPhone verification. V1 will report JamesDSP live processing unavailable on iOS unless `liveAudioIOS` is on; EqRender/offline rendered playback remains Standard. Text effects (Liveprog, DDC, arbitrary text EQ) will be neither shown nor accepted by the v1 settings/import surface. IR state is memory-only because JSON presets do not contain its PCM.
+
+## Licensing and release boundaries
+
+The standalone source is pinned by commit in the vendor `VERSION` file and its supplied notices are retained. Its upstream `Main/LICENSE` contains GPL-2.0 text while the port documents GPL-3.0-or-later additions; this discrepancy is recorded and no license file will be silently rewritten. A redistribution decision remains an owner release matter. The user instruction prohibits pushing or deploying, so Phase 7 will prepare beta listening notes only and will not publish a beta build.
--- a/plans/jamesdsp-integration-report.md
+++ b/plans/jamesdsp-integration-report.md
@@ -0,0 +1,30 @@
+# JamesDSP integration report — 2026-10-10
+
+JamesDSP now uses the shared `AudioGraph`, remains opt-in, and is delivered as a lazy feature. The upstream port is pinned to `a982b53c4ab347d1d9c50f4ce7ee3c2735eaa817`. It adds four-channel convolution, generated and IndexedDB-stored IRs, spatial/HRTF processing, and 8–96 kHz sample-rate conversion. Settings expose IR selection/upload and bounded controls for convolution and spatial audio. Long IRs are constrained on low-resource devices. Standard remains an exact bypass route; failed DSP/WASM initialization returns to Standard. iOS playback remains gated by `liveAudioIOS`.
+
+The legacy lossy-update timeout came from the new worker hashing/copying the entire legacy shell during `activate`, while the b77938a page reloads on a short timer after the user presses Refresh UI. The worker now stages and verifies legacy assets during `install`; activation only commits the staged cache. The lossy migration harness passes both engines, preserving the user-initiated legacy update flow.
+
+The DSP WASM is now marked `offlineOptIn: "jamesDsp"`. Normal completion caches the 103 required files and defers all 9 optional DSP files, including the ~1.2 MB WASM. Enabling “download audio effects for offline” persists the opt-in and resumes completion. Cold transfer is back near the pre-DSP baseline.
+
+| Verification | Result |
+|---|---|
+| Frontend tests | 271 passed, 0 failed |
+| Server tests | Previously run after integration: all pass except the two known `yt_dlp` environment failures; remaining server tests passed individually |
+| Offline completion | Chromium + WebKit: 112/112 after explicit opt-in; 103 required + 9 optional deferred by default; zero missing/failures |
+| Lazy / hidden timers | Both browsers pass; lazy asserts DSP WASM remains uncached by default; no hidden-timer page errors |
+| UI geometry / icons | 384 geometry cases and 24 layout/theme icon cases passed |
+| Settings persistence | Old-client Refresh UI preserved all existing keys in both engines; only intentional additions/migrations are the disabled `jamesDsp` default and 5→10 EQ migration. Save-before-play works before and after update. DSP preset/parameters and offline opt-in persist. Linux WebKit lacks native OPFS, so its save-play assertion is explicitly unsupported. |
+| DSP harness | Both engines pass: four-channel IR changes output (interaural RMS 0.00735), spatial stage changes it (0.02154 vs dry 0), 32 kHz context, exact bypass, offline reload with stored IR, one DSP heap, corrupt-WASM fallback |
+
+Migration (`node perf/migration.mjs --browser all`) passed lossy and unthrottled after the worker fix. Lossy wire totals: Chromium 652,568 bytes / 26.4 s; WebKit 746,826 bytes / 20.1 s. Unthrottled: Chromium 664,110 bytes / 11.2 s; WebKit 790,706 bytes / 7.7 s. Each run showed one banner/reload, offline launch, and playback guard.
+
+Three-run cold LTE medians (`node perf/baseline.mjs --runs 3 --browser all --profile lte --scenario cold`):
+
+| Engine | FCP before → now | LCP now | Wire before → now | Requests now | Positive `app.js` responses |
+|---|---:|---:|---:|---:|---:|
+| Chromium | 1360 → 1348 ms | 1348 ms | 648 KB → 1.82 MB → 673,992 B | 117 | 1 |
+| WebKit | 895 → 908 ms | 976 ms | 976 KB → 2.14 MB → 1,020,231 B | 161 | 1 |
+
+The wire columns are pre-DSP baseline → initial DSP integration before the opt-in correction → current. The correction removes roughly 1.2 MB from first install while leaving the DSP assets available after explicit opt-in.
+
+The harness JSON is `perf/.tmp/dsp-cold-final.json`; it records 274 ms Chromium long-task total and 0 ms in WebKit. No real iPhone, lock-screen session, thermal behavior, or listening/ear-tuning test was possible. Verify iOS opt-in, background audio, CPU use with long IRs, and the perceived level/space before enabling this for users. Phase 7 deployment was not run.
--- a/plans/settings-shots/chromium-bento-hub-contrast.png
+++ b/plans/settings-shots/chromium-bento-hub-contrast.png
--- a/plans/settings-shots/chromium-bento-hub-dark.png
+++ b/plans/settings-shots/chromium-bento-hub-dark.png
--- a/plans/settings-shots/chromium-bento-hub-light.png
+++ b/plans/settings-shots/chromium-bento-hub-light.png
--- a/plans/settings-shots/chromium-classic-contrast.png
+++ b/plans/settings-shots/chromium-classic-contrast.png
--- a/plans/settings-shots/chromium-classic-dark.png
+++ b/plans/settings-shots/chromium-classic-dark.png
--- a/plans/settings-shots/chromium-classic-light.png
+++ b/plans/settings-shots/chromium-classic-light.png
--- a/plans/settings-shots/chromium-f7-swipe-contrast.png
+++ b/plans/settings-shots/chromium-f7-swipe-contrast.png
--- a/plans/settings-shots/chromium-f7-swipe-dark.png
+++ b/plans/settings-shots/chromium-f7-swipe-dark.png
--- a/plans/settings-shots/chromium-f7-swipe-light.png
+++ b/plans/settings-shots/chromium-f7-swipe-light.png
--- a/plans/settings-shots/chromium-glass-stage-contrast.png
+++ b/plans/settings-shots/chromium-glass-stage-contrast.png
--- a/plans/settings-shots/chromium-glass-stage-dark-dsp.png
+++ b/plans/settings-shots/chromium-glass-stage-dark-dsp.png
--- a/plans/settings-shots/chromium-glass-stage-dark-spatial.png
+++ b/plans/settings-shots/chromium-glass-stage-dark-spatial.png
--- a/plans/settings-shots/chromium-glass-stage-dark.png
+++ b/plans/settings-shots/chromium-glass-stage-dark.png
--- a/plans/settings-shots/chromium-glass-stage-light.png
+++ b/plans/settings-shots/chromium-glass-stage-light.png
--- a/plans/settings-shots/measurements.json
+++ b/plans/settings-shots/measurements.json
@@ -0,0 +1,30 @@
+{
+  "cases": 120,
+  "failures": [],
+  "screenshots": [
+    "chromium-classic-dark.png",
+    "chromium-classic-light.png",
+    "chromium-classic-contrast.png",
+    "chromium-f7-swipe-dark.png",
+    "chromium-f7-swipe-light.png",
+    "chromium-f7-swipe-contrast.png",
+    "chromium-glass-stage-dark.png",
+    "chromium-glass-stage-light.png",
+    "chromium-glass-stage-contrast.png",
+    "chromium-bento-hub-dark.png",
+    "chromium-bento-hub-light.png",
+    "chromium-bento-hub-contrast.png",
+    "webkit-classic-dark.png",
+    "webkit-classic-light.png",
+    "webkit-classic-contrast.png",
+    "webkit-f7-swipe-dark.png",
+    "webkit-f7-swipe-light.png",
+    "webkit-f7-swipe-contrast.png",
+    "webkit-glass-stage-dark.png",
+    "webkit-glass-stage-light.png",
+    "webkit-glass-stage-contrast.png",
+    "webkit-bento-hub-dark.png",
+    "webkit-bento-hub-light.png",
+    "webkit-bento-hub-contrast.png"
+  ]
+}
--- a/plans/settings-shots/webkit-bento-hub-contrast.png
+++ b/plans/settings-shots/webkit-bento-hub-contrast.png
--- a/plans/settings-shots/webkit-bento-hub-dark.png
+++ b/plans/settings-shots/webkit-bento-hub-dark.png
--- a/plans/settings-shots/webkit-bento-hub-light.png
+++ b/plans/settings-shots/webkit-bento-hub-light.png
--- a/plans/settings-shots/webkit-classic-contrast.png
+++ b/plans/settings-shots/webkit-classic-contrast.png
--- a/plans/settings-shots/webkit-classic-dark.png
+++ b/plans/settings-shots/webkit-classic-dark.png
--- a/plans/settings-shots/webkit-classic-light.png
+++ b/plans/settings-shots/webkit-classic-light.png
--- a/plans/settings-shots/webkit-f7-swipe-contrast.png
+++ b/plans/settings-shots/webkit-f7-swipe-contrast.png
--- a/plans/settings-shots/webkit-f7-swipe-dark.png
+++ b/plans/settings-shots/webkit-f7-swipe-dark.png
--- a/plans/settings-shots/webkit-f7-swipe-light.png
+++ b/plans/settings-shots/webkit-f7-swipe-light.png
--- a/plans/settings-shots/webkit-glass-stage-contrast.png
+++ b/plans/settings-shots/webkit-glass-stage-contrast.png
--- a/plans/settings-shots/webkit-glass-stage-dark-dsp.png
+++ b/plans/settings-shots/webkit-glass-stage-dark-dsp.png
--- a/plans/settings-shots/webkit-glass-stage-dark-spatial.png
+++ b/plans/settings-shots/webkit-glass-stage-dark-spatial.png
--- a/plans/settings-shots/webkit-glass-stage-dark.png
+++ b/plans/settings-shots/webkit-glass-stage-dark.png
--- a/plans/settings-shots/webkit-glass-stage-light.png
+++ b/plans/settings-shots/webkit-glass-stage-light.png
--- a/tests/admin-lyrics.spec.js
+++ b/tests/admin-lyrics.spec.js
@@ -150,18 +150,3 @@ test('player lyric editor groups Shift+Enter words and stamps their shared cue',
  const document = await text.inputValue(); expect(document).toContain('[0:00.00] Because You are God\n| You can do anything');
  expect(document).not.toContain('[0:00.00] |');
 });
-test('editor loads the whole audio into the browser once and reuses it', async ({ page }) => {
-  const wav = Buffer.alloc(44 + 16000); // 1 s of silence, 8 kHz 16-bit mono
-  wav.write('RIFF', 0); wav.writeUInt32LE(36 + 16000, 4); wav.write('WAVEfmt ', 8); wav.writeUInt32LE(16, 16);
-  wav.writeUInt16LE(1, 20); wav.writeUInt16LE(1, 22); wav.writeUInt32LE(8000, 24); wav.writeUInt32LE(16000, 28);
-  wav.writeUInt16LE(2, 32); wav.writeUInt16LE(16, 34); wav.write('data', 36); wav.writeUInt32LE(16000, 40);
-  let hits = 0;
-  await fixture(page);
-  await page.route('**/api/media/' + id + '?a=1', route => { hits++; route.fulfill({ contentType: 'audio/wav', body: wav }); });
-  await page.locator('[data-open="' + id + '"]').first().click();
-  await expect(page.locator('#dur')).toHaveText('0:01');
-  expect(hits).toBe(1);
-  await page.reload(); await page.locator('[data-open="' + id + '"]').first().click();
-  await expect(page.locator('#dur')).toHaveText('0:01');
-  expect(hits).toBe(1);
-});
--- a/tests/fixtures/standard-eq-build.txt
+++ b/tests/fixtures/standard-eq-build.txt
@@ -0,0 +1,31 @@
+  function build() {
+    if (st.ctx) return true;
+    if (!Lazy.loaded('feature:eq-core') || !Lazy.loaded('feature:vocal-reducer')) {
+      loadSoundFeatures().then(()=>{apply(); Level.apply();}).catch(error=>toast(error.message));
+      return false;
+    }
+    try {
+      st.ctx = new AC();
+      st.filters = EQ_BANDS.map((b) => {
+        const f = st.ctx.createBiquadFilter();
+        f.type = b.type;
+        f.frequency.value = b.f;
+        f.Q.value = 1.0;
+        return f;
+      });
+      for (let i = 0; i < st.filters.length - 1; i++) st.filters[i].connect(st.filters[i + 1]);
+      // Loudness levelling: gain toward -14 LUFS, then a limiter so a boosted
+      // quiet track can never clip.
+      st.level = st.ctx.createGain();
+      st.limiter = st.ctx.createDynamicsCompressor();
+      st.limiter.threshold.value = -1; st.limiter.knee.value = 0; st.limiter.ratio.value = 20;
+      st.limiter.attack.value = 0.003; st.limiter.release.value = 0.25;
+      st.vocal = VocalReducer.create(st.ctx, st.filters[st.filters.length - 1]);
+      st.widener = EqCore.createWidener(st.ctx, st.vocal.output);
+      st.widener.output.connect(st.level);
+      st.level.connect(st.limiter);
+      st.limiter.connect(st.ctx.destination);
+      return true;
+    } catch { st.ctx = null; return false; }
+  }
+
Author	SHA1	Message	Date
Jonathan Sykes	7f49c317fd	Merge retry hardening with DSP cache opt-in	2026-10-10 23:00:32 +08:00
Jonathan Sykes	f0daeaedd2	Fix responsive DSP settings controls	2026-10-10 22:50:02 +08:00
Jonathan Sykes	0c387a01cd	Record DSP integration verification and optional cache results	2026-10-10 19:42:14 +08:00
Jonathan Sykes	e0802aa8a8	Wait for DSP opt-in persistence in settings harness	2026-10-10 19:32:12 +08:00
Jonathan Sykes	865c60cb85	Fix offline opt-in persistence assertion	2026-10-10 19:29:31 +08:00
Jonathan Sykes	ef12468a99	Extend JamesDSP with convolution and spatial audio	2026-10-10 19:25:06 +08:00
Jonathan Sykes	b3f0525a8e	Stage legacy asset migration before activation	2026-10-10 18:40:32 +08:00
Jonathan Sykes	d02796b0eb	Retry transient foreground requests before surfacing errors	2026-10-09 21:53:03 +08:00
Jonathan Sykes	7591c2d14c	Record JamesDSP integration verification results	2026-10-09 21:08:58 +08:00
Jonathan Sykes	6bb3271431	Add JamesDSP playback controls and verification harness	2026-10-09 20:29:37 +08:00
Jonathan Sykes	27b32ff0c9	Add the guarded JamesDSP audio controller	2026-10-09 20:00:49 +08:00
Jonathan Sykes	aca50c1690	Vendor JamesDSP in a lazy asset group	2026-10-09 19:52:17 +08:00
Jonathan Sykes	76037613a7	Extract the shared realtime audio graph owner	2026-10-09 19:46:00 +08:00
Jonathan Sykes	d6a3570ff9	Document JamesDSP audio ownership audit	2026-10-09 19:42:11 +08:00