diag(audio): live audio-status readout + native test player; stop swallowing play errors

Three blind fixes failed because headless browsers relax autoplay (can't reproduce)
and play() errors were swallowed. Instrument instead:
- #audio-status: live readout (playing/paused/blocked/media-error) under the toggle
- surface the play() rejection reason + element error (was .catch(()=>{}))
- 'Audio check' fieldset with a native <audio controls> on the soundtrack file, to
  test the file directly with zero app code in the path
Diagnostic only — no behavior change. 37 tests pass.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

sessions/0021/SESSION-0021.0-TRANSCRIPT-2026-06-26T08-12--2026-06-26T08-20.md

@@ -0,0 +1,88 @@
+# Session 0021.0 — Transcript
+
+> App: human-experience-filter-art
+> Start: 2026-06-26T08-12 (PST)
+> End: 2026-06-26T08-20 (PST)
+> Type: executing-plans (operator-driven hotfix/revision of session 0020's audio feature)
+> Posture: yolo
+> Claude-Session: e0cc053a-41fa-416d-a4f5-493f14984e75
+> Status: FINALIZED
+
+## Launch prompt
+
+> Show video unchecked doesn't turn off the video. Make "show video" just "Video"
+> and have a toggle like "Dev Mode" has. I can't hear any audio when "soundtrack
+> (follows altitude)" is selected. Let's just have Audio as off/on like Video for
+> now and get rid of white noise.
+
+## Pre-state
+
+- Session 0020 had just merged the audio feature to `main` (Visual×Audio split,
+  per-altitude soundtracks, pink white-noise, A/B crossfade). The operator tested it
+  live and reported three issues.
+
+## Session arc
+
+1. **Diagnosis (the key work).** Both reported bugs were reproduced *only* in the
+   operator's real browser — neither appeared in headless Chromium **or** WebKit
+   (installed `playwright install webkit` to test Safari's engine). Root causes:
+   - **Video-off doesn't blank:** `#vid` (`<video>`) and `#paint` (WebGL `<canvas>`)
+     are GPU-composited layers; the `#black` cover had *auto* z-index, so on a real
+     GPU (Safari/Chrome) the video layer can composite *above* it despite DOM order.
+     Headless software-raster hides this.
+   - **No soundtrack audio:** real Safari/iOS unlocks an `<audio>` element only when
+     `play()` is called *synchronously inside* the user gesture; the 0020 gesture
+     played in an async continuation (after `await fetch`), which Chrome allows but
+     Safari blocks. Headless WebKit relaxes autoplay, so it passed.
+   This is the session's main lesson: **Playwright headless relaxes both GPU
+   compositing and autoplay**, so the 0020 E2E couldn't have caught either — real
+   device / by-eye review is required.
+2. **Fixes (branch `session-0021`):**
+   - **Video** + **Audio** are now Dev-Mode-style on/off toggles (`.dev-switch`),
+     wired on `change`. Audio on → soundtrack; **white-noise deferred** (removed from
+     the live control; `AUDIO_SOURCES={off,soundtrack}`; the pure pink-noise
+     machinery + tests stay for later).
+   - Video-off: `.black` gets `z-index:50` + `translateZ(0)` (own layer) **and** the
+     video layers are set `opacity:0` on video-off (belt-and-suspenders blanking).
+   - Safari audio: the tap-to-start gesture now primes both A/B `<audio>` elements
+     **synchronously in-gesture** (set src, vol 0, `play().then(pause)`), unlocking
+     the later async crossfades.
+   - Server: `player/audio.py` resolver + `controls.py`/`state.py` + `/api/alteration`
+     drop white-noise; `build_audio_media.py` stops emitting the noise bed.
+3. **Verify + ship.** Updated unit/contract/E2E tests; rewrote the 3 E2E for the new
+   toggles (click the visible `.dev-switch-track`; wait for the opacity transition).
+   **288 passed, 2 skipped.** Re-verified in **both Chromium and WebKit**: Audio toggle
+   plays `cosmos/pillars.loop.mp3`, video-off sets vid+paint opacity 0 with `#black`
+   shown, zero JS errors; screenshotted the new toggle UI. Merged `session-0021` →
+   `main` and pushed. (Also untracked a stray `docs/.threads/*.json` editor artifact
+   swept in by `git add -A`, and gitignored `.threads/`.)
+
+## Deferred decisions
+
+_No low-confidence calls. All three changes were explicit operator requests; the
+root-cause fixes (GPU z-index/layer-hide; Safari in-gesture unlock) are the standard
+remedies for these well-known browser behaviors._
+
+## Cut state
+
+- `main` @ `fddb6d6` (merge of session-0021), clean, pushed.
+- **288 tests + 3 Playwright E2E pass** (2 skipped: opt-in media integration).
+- White-noise is deferred, not deleted: `tools/pipeline/audio_ops.white_noise_args` +
+  `audio_run.generate_white_noise` + their tests remain; only the live control + the
+  build-script emission were removed.
+- **Unvalidated by this session:** real-device audio (Safari autoplay) and real-GPU
+  video-off — headless can't exercise either; needs the operator's by-ear/by-eye pass.
+
+## Operator plate
+
+- Video + Audio are simple on/off toggles (Dev-Mode style). Audio on = the current
+  altitude's soundtrack. The two real-browser bugs should now be fixed — but please
+  confirm on a real device (especially iPad/Safari).
+- Deferred: white-noise (easy to re-add as a 3rd Audio position), the per-altitude
+  music layer, the networked-control-surface build, Pi renderer.
+
+## Next /goal
+
+```
+/goal by-ear/by-eye review the audio + Video/Audio toggles on a REAL device (esp. iPad/Safari — headless can't validate Safari autoplay or GPU compositing), then source/compose the deferred per-altitude music layer per docs/audio-candidate-pool.md (or re-enable white-noise as a 3rd Audio position if wanted)
+```

sessions/sessions.json

@@ -58,5 +58,8 @@
   },
   "0020": {
     "title": ""
+  },
+  "0021": {
+    "title": ""
   }
 }

simulator/static/app.js

@@ -920,8 +920,29 @@ function devLiveReload() {
 // (e.g. on an altitude change). audio on = the current scale's soundtrack.
 const aud = $("aud");
 let audUrl = null;                      // soundtrack url currently loaded (null = silent)
+let audLastErr = "";                    // last play() rejection / element error (for the readout)
 const FADE_MS = 500;
 
+// --- Live audio status readout (diagnostic) — so a "no sound" report is legible ---
+const AUD_ERR = ["", "aborted", "network", "decode", "format-not-supported"];
+function audioStatusText() {
+  if (!$("audio").checked) return "audio: off";
+  if (aud.error) return `audio: MEDIA ERROR ${aud.error.code} (${AUD_ERR[aud.error.code] || "?"})`;
+  if (audLastErr) return "audio: " + audLastErr;
+  if (aud.paused) return `audio: on, PAUSED (readyState ${aud.readyState})`;
+  return `audio: ▶ playing ${aud.currentTime.toFixed(1)}s · vol ${Math.round(aud.volume * 100)}% · rs ${aud.readyState}`;
+}
+function updateAudioStatus() {
+  const el = $("audio-status");
+  if (!el) return;
+  el.textContent = audioStatusText();
+  const playing = $("audio").checked && !aud.paused && !aud.error && !audLastErr;
+  el.classList.toggle("playing", playing);
+  el.classList.toggle("blocked", !!aud.error || !!audLastErr);
+}
+aud.addEventListener("error", () => { audLastErr = ""; updateAudioStatus(); });
+setInterval(updateAudioStatus, 400);
+
 function fadeVolume(el, to, ms, done) {
   // setInterval (not requestAnimationFrame): rAF throttles/pauses when the tab is
   // backgrounded, which would stall the gain ramp; a timer fires regardless.
@@ -947,8 +968,12 @@ function soundtrackUrl() {
 function playUrl(url) {
   aud.src = mediaUrl(url);
   aud.volume = 0;
+  audLastErr = "";
   const pr = aud.play();
-  if (pr) pr.catch(() => {});
+  if (pr) {
+    pr.then(() => { audLastErr = ""; updateAudioStatus(); })
+      .catch((e) => { audLastErr = "play BLOCKED: " + ((e && e.name) || e); updateAudioStatus(); });
+  }
   fadeVolume(aud, 1, FADE_MS);
 }
 

simulator/static/index.html

@@ -40,6 +40,15 @@
           <span class="dev-switch-track"><span class="dev-switch-thumb"></span></span>
           <span class="dev-switch-label">Audio</span>
         </label>
+        <div id="audio-status" class="audio-status">audio: off</div>
+      </fieldset>
+
+      <fieldset>
+        <legend>Audio check (diagnostic)</legend>
+        <p class="hint">Press play below to test the soundtrack file directly in the
+          browser's own player — this bypasses all app code. If you hear it here but
+          not from the Audio toggle, the file is fine and it's a code/autoplay issue.</p>
+        <audio id="aud-test" controls preload="auto" src="/media/audio/cosmos/pillars.loop.mp3" style="width:100%"></audio>
       </fieldset>
 
       <fieldset>

simulator/static/style.css

@@ -49,6 +49,10 @@ main { display: flex; gap: 1rem; padding: 1rem; flex-wrap: wrap; align-items: fl
 .hidden { display: none; }
 /* Stack the two Output toggles (Video / Audio) with a little breathing room. */
 .dev-switch + .dev-switch { margin-top: 0.45rem; }
+/* Live audio status readout (diagnostic) — turns green when actually playing. */
+.audio-status { margin-top: 0.5rem; font: 11px/1.4 monospace; color: #9ab; }
+.audio-status.playing { color: #4e9; }
+.audio-status.blocked { color: #f97; }
 .panel { flex: 0 0 280px; display: flex; flex-direction: column; gap: 0.8rem;
          max-height: calc(100vh - 2rem); overflow-y: auto;
          position: sticky; top: 1rem; }