§4c audio spike

build 2 — media session

4 × 30s work / 20s jog, compressed. Every tone is scheduled onto the Web Audio graph up front at absolute currentTime offsets — no setInterval/setTimeout. Build 2 adds a real looping <audio> element and Media Session registration so iOS treats this as active media playback rather than a bare Web Audio session it can tear down on lock.

Lock the screen now. The countdown above may freeze while locked — that's expected, the tones do not depend on it. You should see MyBlock as playing media on the lock screen; if that card disappears, the session was torn down and the log will say when. Unlock once you've heard the end tone (three descending beeps) and read the summary.