start/stop_screen_recording produces corrupt files on Android and silently fails on iOS physical devices

[Cariocecuz]

Describe the bug

mobile_start_screen_recording / mobile_stop_screen_recording issue on physical devices for both platforms:

• Android: start succeeds, stop returns a file path, size, and duration — appearing to work. However, the output MP4 is always corrupt: it's missing the moov atom (the metadata/index header), making it unplayable in any player. ffprobe confirms: moov atom not found — Invalid data found when processing input. Reproduced 4/4 times.

• iOS: start returns success, but stop returns No active recording found for device — Start a recording first. No file is ever created on disk. Reproduced 2/2 times.

  The same Android device recorded via adb screenrecord produces valid, playable MP4 files 4/4 times, confirming the issue is
  in the MCP tool's stop/finalization logic, not the device.

  Configuration:
  • Agent: Augment Code (Claude)
  • OS: macOS
  • Devices used: Android physical, iOS physical
  • Device versions: Android 14, iOS 26.2
  • Device models: Pixel 7, iPhone 15

  To Reproduce

  Android:

  1. mobile_start_screen_recording with an output path
  2. Interact with the device (tap, swipe, navigate)
  3. mobile_stop_screen_recording — tool reports success with file size and duration
  4. Try to open the file — it's unplayable. ffprobe reports moov atom not found

  iOS:

  1. mobile_start_screen_recording with an output path — tool reports success
  2. Interact with the device
  3. mobile_stop_screen_recording — returns No active recording found for device
  4. No file exists at the output path

  Expected behavior

  A valid, playable MP4 file is saved to the specified path after stop_screen_recording.

  Actual behavior

  • Android: Corrupt MP4 (raw H.264 data present but moov atom never written — container not finalized)
  • iOS: No file created at all; recording state lost between start and stop

  Comparison with ADB (Android baseline — works 4/4):

  Start recording on device
  adb -s <DEVICE_ID> shell screenrecord /sdcard/recording.mp4 --time-limit 120 &

  Stop recording (SIGINT finalizes the mp4 container / writes moov atom)
  adb -s <DEVICE_ID> shell "kill -2 $(adb -s <DEVICE_ID> shell pgrep screenrecord)"

  Wait for finalization
  sleep 3
  Pull file from device
  adb -s <DEVICE_ID> pull /sdcard/recording.mp4 /tmp/recording.mp4

  Remux with faststart flag (moves moov atom to front for compatibility)
  ffmpeg -i /tmp/recording.mp4 -c copy -movflags +faststart output.mp4

  The key difference: ADB's screenrecord properly writes the moov atom when it receives SIGINT (kill -2). The MCP tool's
  stop_screen_recording is not finalizing the MP4 container on Android, and on iOS it loses track of the recording process
  entirely.

  Screenshots
  N/A — the issue is corrupt/missing files, not a visual bug.

[agrosner]

+1 to this issue. taking videos just straight up doesnt work.