Clickable previews: exact app deep-links everywhere

Every rendered still links to the app frame that produced it (song + seed + frame + venue/viz pins + probe warm-up, new window), via shared src/ui/preview.js. Supporting work, each measured: app honors ?frame/?venueSel/?viz/?warm= with pre-build pins (Show.applyPins) and primes deep-link loads; shared pinViz/pinVenueShell paths for gallery, filmstrip and app; probes prime and carry their warm-up; bank probes analyse the bank PCM and file decode is fixed-rate with bit-exact WAV parsing so app and probes see identical samples; materials built mid-update compile synchronously (needsCompile). Round trip verified bit-identical gallery-versus-app.

flow-state/tools/build-song-bank.js

@@ -22,7 +22,7 @@ import { resolve, dirname } from 'node:path';
 import { fileURLToPath } from 'node:url';
 import { synthesizeSong } from '../src/audio/synth.js';
 import { FeatureTrack } from '../src/audio/FeatureTrack.js';
-import { SONGS, AXES } from '../src/audio/songbank.js';
+import { SONGS, AXES, bankPcm } from '../src/audio/songbank.js';
 
 const here = dirname(fileURLToPath(import.meta.url));
 
@@ -41,7 +41,9 @@ const CHECK_ONLY = has('check');
  * 16-bit PCM WAV, mono.
  *
  * Mono halves the size and loses nothing: the analyser sums to mono before it
- * does anything, and the synth writes the same signal to both channels anyway.
+ * does anything, the synth writes the same signal to both channels anyway —
+ * and the probes analyse the mono bank PCM, so the files must be mono for
+ * app and probe features to match bit-exactly. See songbank.js bankPcm.
  */
 function wav(samples, sampleRate) {
     const bytes = samples.length * 2;
@@ -63,13 +65,12 @@ function wav(samples, sampleRate) {
     // Peak-normalise to -1 dBFS. Without it the quiet ambient entries clip down
     // into 16-bit noise and their measured flatness stops being what the spec
     // asked for — the bank would then be testing the encoder, not the generator.
-    let peak = 0;
-    for (let i = 0; i < samples.length; i++) peak = Math.max(peak, Math.abs(samples[i]));
-    const gain = peak > 1e-9 ? 0.89 / peak : 1;
+    // Shared with songbank.js bankPcm: the files must hold exactly what the
+    // probes analyse, or app-vs-probe previews can never match.
+    const pcm = bankPcm(samples);
 
-    for (let i = 0; i < samples.length; i++) {
-        const v = Math.max(-1, Math.min(1, samples[i] * gain));
-        buffer.writeInt16LE(Math.round(v * 32767), 44 + i * 2);
+    for (let i = 0; i < pcm.length; i++) {
+        buffer.writeInt16LE(Math.round(pcm[i] * 32768), 44 + i * 2);
     }
     return buffer;
 }
@@ -92,7 +93,19 @@ for (const spec of SONGS) {
         transition: spec.transition ?? 0.5,
         seed: 1 + SONGS.indexOf(spec),
     });
-    const track = FeatureTrack.fromAudioBuffer(buffer, { fps: 60 });
+    // Measured from the bank PCM — the same samples the files hold and the
+    // probes analyse (see songbank.js bankPcm) — not the raw synth.
+    const pcm = bankPcm(buffer.getChannelData(0));
+    const track = FeatureTrack.fromAudioBuffer({
+        sampleRate: buffer.sampleRate,
+        length: pcm.length,
+        duration: buffer.duration,
+        numberOfChannels: 1,
+        getChannelData: (i) => {
+            if (i !== 0) throw new Error('bank is mono');
+            return pcm;
+        },
+    }, { fps: 60 });
 
     if (!CHECK_ONLY) {
         writeFileSync(resolve(OUT, `${spec.name}.wav`),