The linger path called voice.update({volume:0}) before kill(voice,tail) — update sets volume instantly (no ramp), muting the voice before the fade could run, so releasing a key during shift-linger stopped the sound at once instead of ringing out. Drop the instant-mute; kill(voice,tail) alone ramps the engine's fade 1→0 over the tail (~4s sustained / 1.2s staccato) for the long decay.