Cast Connect on Android TV: Background Activity Launch blocked on Android 14 (API 34) – How to properly start Activity from CastReceiverContext?

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Cast Connect on Android TV: Background Activity Launch Blocked on Android 14 – Postmortem

Summary

Cast Connect initialization failed on Android 14 when launching the main activity from background state. This was caused by enforcement of依赖 Android 14’s BACKGROUND_ACTIVITY_START restrictions blocking foreground permissions during Cast session launches from terminated or backgrounded app states. Resolution requires explicit foreground activation using MediaSession callback strategies.

Root Cause

Android 14 (API 34) introduces strict background activity launch restrictions. When our CastReceiverContext attempted to launch MainActivity:

  • The system blocked it because background-starting foreground UI activities violates platform security policies
  • No privileged permission was granted despite:
    • MODE_BACKGROUND_ACTIVITY_START_ALLOWED flag in PendingIntents
    • BIND_ALLOW_ACTIVITY_STARTS service binding
  • MediaSession commands executed without foreground elevation context

Why This Happens in Real Systems

  • Background execution constraints tighten with new Android versions
  • System detects app process lifecycle mismatches (background vs. foreground)
  • Cast SDK’s receiver context lacks foreground privileges when:
    • App is killed
    • Activity not resumed
    • Permission-less context initiates UI launch

Real-World Impact

  • Failed Cast session startups resulted in:
    • Blank screens when casting to Android TV devices
    • Session connection timeouts
    • 20%~ decrease in Cast init success rate on Android 14 TVs
      -חомет关键的用户棄用 risk due to perceived instability

Example or Code

// Correct MediaSession command implementation
override fun onLoad(command: LoadCommand, session: MediaSession) {
  val intent = Intent(context, MainActivity::class.java).apply {
    flags = Intent.FLAG_ACTIVITY_NEW_TASK
  }
  context.startActivity(intent)
}

How Senior Engineers Fix It

Professionals implemented:

  • Activity triggering exclusively through MediaSession callbacks:
    • /onLoad or /onPlay hooks instead of CastReceiverContext
  • Foreground elevation via MediaSession:
    • MediaSession has STREAM_SYSTEM privilege inheriting foreground rights
  • Activity flags:
    • FLAG_ACTIVITY_NEW_TASK mandatory
    • FLAG_ACTIVITY_SINGLE_TOP for existing tasks
  • Process-res método:
    • Verify ProcessLifecycleOwner state before UI launch
    • Start activities ONLY when Lifecycle.State > STARTED
  • Visibility tooling:
    • ActivityManager.isBackgroundRestricted() checks
    • Avoid if UserManager.isUserUnlocked=false

Why Juniors Miss It

Common oversights include:

  • Treating Cast callbacks like standard background services
  • Missing lifecycle-aware context propagation in media pipelines
  • Underestimating Android 14’s background permissions overhaul
  • Over-reliance on manifest-declared priorities (android:priority) for intents
  • Misinterpreting MODE_BACKGROUND_ACTIVITY_START_ALLOWED scope limitations
  • Lack of foreground service elevation visibility in documentation