Measured with Python wave: frames / sample rate, public/audio/*.wav
WAV count: 101
intro.wav: 8.1205 s
Longest target: message-market.wav: 10.1725 s
AudioEngine scheduling: start +0.05 s; intro-to-target gap +0.35 s
Maximum scheduled intro + target: 18.6930 s
Old assertion headroom (20 s): 1.3070 s
New assertion headroom (30 s): 11.3070 s
Product timeouts remain: preparation 15000 ms; playback scheduled end + 5 s.
Retry control flow: failed play does not set introDone; retry includes intro;
target.onended -> task.finish -> play resolves -> ENDED -> answer group visible.