Sketch architecture for per-app routing before v1 ships to validate forward-compatibility.
Keyboard navigation, VoiceOver labels, contrast for icon states.
Status: Fixed
Fix: AVAudioEngine was using the tap's sample rate (e.g., 48kHz) instead of the output device's native rate (e.g., 44.1kHz for Bluetooth). The resulting implicit resampling caused volume loss and crackling on devices with mismatched rates. Fixed by reading the output device's kAudioDevicePropertyNominalSampleRate and using it for AVAudioEngine's format. The aggregate device handles tap→device resampling natively.