Release the tuner noise graph after a silent dial release

A release that only selects a station now stops the looping noise source and suspends its AudioContext. The qa-radio dial scenarios start from an active stream, or expect a silent release from a stopped Radio.

scripts/qa-radio.mjs

@@ -3073,20 +3073,27 @@ async function main() {
         expectedSlot: targetIndex,
         previewPlayDelta: previewPlays - playsBefore,
         commitPlayDelta: window.__qaRadioPlayCalls.length - playsBefore,
+        audioState: state.audioState,
+        tuningStatic: state.tuningStatic,
         samples,
         spread: Math.max(...samples) - Math.min(...samples),
       };
     });
     check(
-      'pointer preview never plays and release commits the nearest station once without a needle sweep',
+      'from a stopped Radio, pointer release only selects the nearest station, silently and without a needle sweep',
       tunerDirectRelease.targetId
         && tunerDirectRelease.selectedId === tunerDirectRelease.targetId
         && tunerDirectRelease.sliderSlot === tunerDirectRelease.expectedSlot
         && tunerDirectRelease.previewPlayDelta === 0
-        && tunerDirectRelease.commitPlayDelta === 1
+        && tunerDirectRelease.commitPlayDelta === 0
+        && tunerDirectRelease.audioState === 'stopped'
+        && !tunerDirectRelease.tuningStatic
         && tunerDirectRelease.spread < 0.5,
       JSON.stringify(tunerDirectRelease),
     );
+    // The release plays only if a stream was active when the drag began.
+    await page.evaluate(() => window.__godsEyeView.dataManager.layers.get('radio').module.togglePlayback({ origin: 'user' }));
+    await page.waitForFunction(() => window.__godsEyeView.dataManager.layers.get('radio').module.getUIState().audioState === 'playing');
     // Earlier cases scroll and resize the directory. Bring the physical drag
     // target back into its scroller before deriving viewport mouse coordinates.
     await page.$eval('#radio-tuner-slider', (slider) => slider.scrollIntoView({ block: 'center', inline: 'nearest' }));
@@ -3494,6 +3501,9 @@ async function main() {
       });
     });
     await sleep(500);
+    // Next left the Radio stopped; a release plays only from an active stream.
+    await page.evaluate(() => window.__godsEyeView.dataManager.layers.get('radio').module.togglePlayback({ origin: 'user' }));
+    await page.waitForFunction(() => window.__godsEyeView.dataManager.layers.get('radio').module.getUIState().audioState === 'playing');
     const failedTuner = await page.evaluate(async () => {
       const gev = window.__godsEyeView;
       const slider = document.getElementById('radio-tuner-slider');

src/data/radioNextState.test.mjs

@@ -271,3 +271,50 @@ test('a dial release plays only if a stream was active when the drag began', asy
     assert.equal(state.playingStationId, ids[2]);
   });
 });
+
+// Records the tuner noise graph so a test can see whether it was released.
+function withFakeAudioContext(body) {
+  const log = { contexts: [], sources: [] };
+  const node = () => ({ connect() {}, disconnect() {} });
+  class FakeAudioContext {
+    constructor() {
+      Object.assign(this, { state: 'suspended', sampleRate: 8000, currentTime: 0, destination: {} });
+      log.contexts.push(this);
+    }
+    resume() { this.state = 'running'; return Promise.resolve(); }
+    suspend() { this.state = 'suspended'; return Promise.resolve(); }
+    close() { this.state = 'closed'; return Promise.resolve(); }
+    createBuffer(_channels, length) { return { getChannelData: () => new Float32Array(length) }; }
+    createBufferSource() {
+      const source = { ...node(), started: false, stopped: false, start() { this.started = true; }, stop() { this.stopped = true; } };
+      log.sources.push(source);
+      return source;
+    }
+    createBiquadFilter() { return { ...node(), frequency: { value: 0 }, Q: { value: 0 } }; }
+    createGain() {
+      return { ...node(), gain: { value: 0, cancelScheduledValues() {}, setValueAtTime() {}, linearRampToValueAtTime() {} } };
+    }
+  }
+  const original = globalThis.AudioContext;
+  globalThis.AudioContext = FakeAudioContext;
+  return Promise.resolve(body(log)).finally(() => {
+    if (original === undefined) delete globalThis.AudioContext;
+    else globalThis.AudioContext = original;
+  });
+}
+
+test('a silent dial release stops the tuner noise and suspends its audio context', async () => {
+  await withFakeAudioContext(async ({ contexts, sources }) => {
+    await withLayer([], async ({ playUrls }) => {
+      radioLayer.selectStation(ids[0], { autoplay: false });
+      assert.equal(radioLayer.beginTuning(), true);
+      radioLayer.previewTuningStation(ids[1], { rotate: false });
+      assert.equal(radioLayer.commitTuningStation(ids[1], { origin: 'user' }).ok, true);
+      await settle();
+      assert.deepEqual(playUrls, []);
+      assert.equal(sources[0].started, true);
+      assert.equal(sources[0].stopped, true, 'noise source still looping');
+      assert.equal(contexts[0].state, 'suspended', 'audio context still running');
+    });
+  });
+});

src/layers/radio/tuning.js

@@ -214,7 +214,9 @@ export function createTuning({ state: layerState, services, parts, source }) {
     layerState._playFallbackFocus = null;
     layerState._playFallbackOrigin = 'programmatic';
     layerState._playFallbackAttemptId = null;
-    parts.tuningNoise.syncTuningNoiseGain();
+    // Static covers only a connecting stream; a silent release frees the noise graph.
+    if (autoplay) parts.tuningNoise.syncTuningNoiseGain();
+    else parts.tuningNoise.clearRadioTuningNoise({ emit: false });
     parts.presentation.emitState();
     const selected = parts.selection.selectRadioStation(frozenStation.id, {
       autoplay,