Snapshot leaves the snapshot-helper instrumentation running, squatting the single UiAutomation connection

[rpgdev]

Summary

After agent-device snapshot returns, the Android snapshot-helper instrumentation (am instrument -w … SnapshotInstrumentation) is left running, which holds the single Android UiAutomation connection and blocks any other accessibility consumer (uiautomator dump, Espresso, Appium) until it's manually killed.

This is platform-agnostic — not specific to React Native / Fabric. It surfaced alongside a separate Fabric snapshot-content problem, filed separately (see linked issue).

Environment

Reproduced on two different devices spanning Android 10 → 14 and two OEM skins (LG and Xiaomi):

• agent-device: 0.17.6 (latest 0.17.7)
• OS / Node: Fedora Linux 43, Node v22.22.2
• Android SDK / adb: platform-tools, adb 1.0.41
• Device A: LG V35 (LM-V350N), Android 10 (SDK 29), USB
• Device B: POCO 23049PCD8G (Xiaomi marble), Android 14 (SDK 34), USB

Problem — helper instrumentation is left running and locks out UiAutomation

After agent-device snapshot returns, the helper instrumentation is still alive:

$ ps aux | grep "am instrument"
adb -s … shell am instrument -w -e waitForIdleTimeoutMs 500 -e waitForIdleQuietMs 100 \
  -e timeoutMs 5000 -e maxDepth 128 -e maxNodes 5000 -e emitChunks false -e sessionPort 41245 \
  com.callstack.agentdevice.snapshothelper/.SnapshotInstrumentation

Because only one UiAutomation connection can exist at a time, plain uiautomator is now blocked (silent failure — no output, no file written):

$ adb shell uiautomator dump /sdcard/x.xml
$ adb shell ls /sdcard/x.xml
… No such file or directory

Killing the helper restores it immediately:

$ adb shell am force-stop com.callstack.agentdevice.snapshothelper
$ adb shell uiautomator dump /sdcard/x.xml
UI hierchary dumped to: /sdcard/x.xml      # works again

Minimal reproduction

1. agent-device snapshot --platform android on any device.
2. ps aux | grep "am instrument" → helper still running after the command returned.
3. adb shell uiautomator dump /sdcard/x.xml; adb shell ls /sdcard/x.xml → now fails/empty. (On Android 11+, use /data/local/tmp/x.xml.)
4. adb shell am force-stop com.callstack.agentdevice.snapshothelper → step 3 works again.

Impact

The leaked instrumentation breaks fallback tooling (uiautomator / Espresso / Appium) in the same session. (Possibly adjacent to #791, which reported a leftover/suspended iOS runner app.)

[thymikee]

Thanks, this is actionable as a separate Android helper lifecycle bug. I labeled it bug; no extra repro info needed right now.

Likely next step: ensure non-daemon/one-shot snapshot cleanup stops the persistent snapshot-helper session after capture, or only keep persistent reuse under a lifecycle that guarantees cleanup. #850 is related but separate: bad snapshot content on Fabric.