️🛠 - iOS audio session and background playback

[maxwellmattryan]

Description

Configure iOS audio session management for proper playback behavior. iOS requires explicit AVAudioSession configuration — HTML5 Audio in WKWebView does not automatically support background playback, lock screen controls, or audio interruption handling.

This is a prerequisite for the preview playback feature (#54) on mobile.

Scope:

• Configure AVAudioSession category (.playback) via a Tauri iOS plugin or native Swift bridge
• Add background audio entitlement (UIBackgroundModes: audio) in the Xcode project configuration
• Handle audio interruptions:
  • Phone calls: pause playback, resume after call ends
  • Siri activation: duck or pause audio
  • Other apps playing audio: respond appropriately
• Integrate MPNowPlayingInfoCenter for lock screen controls:
  • Display artwork, track name, artist name
  • Play/pause, previous/next track controls
  • Progress bar / scrubber
• Handle audio route changes:
  • Bluetooth disconnect → pause playback
  • Headphone unplug → pause playback
  • Route change notification handling
• Validate that the axum proxy (proxy.rs) continues serving audio data when the app is backgrounded
• Ensure the Tokio runtime does not get suspended by iOS when audio is playing in the background

Key files:

• Xcode project settings (entitlements, capabilities)
• New Tauri iOS plugin or Swift bridge code
• src-tauri/src/proxy.rs — validate background behavior

Open questions

• Should audio session configuration be a Tauri plugin (reusable) or inline Swift code in the iOS project?
• Does Tauri v2's iOS runtime keep the Tokio runtime alive during background audio playback, or does iOS suspend it?
• How should MPNowPlayingInfoCenter receive track metadata — via Tauri IPC from the frontend, or directly from the Rust backend?

Acceptance criteria

• Audio continues playing when the app is backgrounded or the screen is locked
• Lock screen shows Now Playing controls with track info and artwork
• Play/pause, previous/next controls work from the lock screen and Control Center
• Audio pauses when a phone call is received and resumes after
• Audio pauses when headphones are unplugged or Bluetooth disconnects
• The axum proxy remains responsive during background playback

Tasks

TBD