android auto support

src/audio/applyNormalization.ts

@@ -0,0 +1,62 @@
+// Headless-safe per-track normalization. `useNormalizationSync` (the richer version with
+// upcoming-track prefetch + oscilloscope gain) is a React hook that only runs while the UI
+// is mounted — so playback started from Android Auto / Bluetooth with the app closed never
+// got normalized. This applies the current track's gain from the headless PlaybackService.
+
+import TrackPlayer from 'react-native-track-player';
+import { useAudioSettingsStore } from '@/stores/audioSettingsStore';
+import { resolveNormalizationGain, type LoudnessFacts } from '@/audio/normalization';
+import { ensureTrackLoudness } from '@/audio/trackAnalysis';
+import {
+  activateTrackGainNative,
+  setNormalizationGainNative,
+  setTrackGainNative,
+} from '@/audio/eqNative';
+
+const EMPTY_FACTS: LoudnessFacts = {
+  loudnessLufs: null,
+  samplePeak: null,
+  replayGainTrackDb: null,
+  replayGainAlbumDb: null,
+  replayGainTrackPeak: null,
+  replayGainAlbumPeak: null,
+};
+
+/**
+ * Resolve + apply the active RNTP track's normalization gain natively. Idempotent and safe
+ * to call alongside `useNormalizationSync` (both compute the same gain). Remote tracks get
+ * unity (no local file / synced facts, and decoding would download the stream).
+ */
+export async function applyNormalizationForActiveTrack(): Promise<void> {
+  const track = await TrackPlayer.getActiveTrack();
+  const url = typeof track?.url === 'string' ? track.url : null;
+  if (!url) {
+    setNormalizationGainNative(1);
+    return;
+  }
+
+  const sourceType = typeof track?.sourceType === 'string' ? track.sourceType : undefined;
+  if (sourceType && sourceType !== 'local') {
+    setNormalizationGainNative(1);
+    return;
+  }
+
+  await useAudioSettingsStore.getState().load();
+  const settings = useAudioSettingsStore.getState().asNormalizationSettings();
+
+  let facts = EMPTY_FACTS;
+  try {
+    facts = await ensureTrackLoudness(url);
+    // Track advanced while we were analyzing — let the newer change win.
+    const now = await TrackPlayer.getActiveTrack();
+    if (typeof now?.url !== 'string' || now.url !== url) return;
+  } catch {
+    /* fall back to unity via EMPTY_FACTS */
+  }
+
+  const resolved = resolveNormalizationGain(facts, settings);
+  // Register by URL (the key the native player swaps on at the media transition) and
+  // activate it now, since no transition fires for the already-current track.
+  setTrackGainNative(url, resolved.linearGain);
+  activateTrackGainNative(url);
+}