fix: harden adaptive audio resume and release

tests/unit/soundtrack-engine.test.ts

@@ -298,6 +298,20 @@ describe('soundtrack engine', () => {
     expect(test.mixer.setDriveLiftAvailableAt).toHaveBeenCalledWith(drive.starts[0]!.at);
   });
 
+  it('does not reload the attached drive lift after resuming established main playback', async () => {
+    const test = createEngineHarness({
+      chapter: resolveChapterIntent('experience'),
+      drive: { energy: 0.8, source: 'physical' },
+    });
+    await test.graph.resume();
+    await test.flushOptionalLoads();
+
+    await test.graph.suspend();
+    await test.graph.resume();
+
+    expect(test.loadCalls.filter((url) => url === '/drive-lift.opus')).toHaveLength(1);
+  });
+
   it('routes drive commands immediately to texture and mixer', () => {
     const test = createEngineHarness();
     const sample = { energy: 0.72, source: 'physical' } as const;