Snapshot on Android RN New Architecture (Fabric) returns only the system window, never the app content

[rpgdev]

Summary

On an Android React Native New-Architecture (Fabric) app, agent-device snapshot never returns the app's view tree — it returns only the system status/navigation-bar window. Plain adb shell uiautomator dump captures the full app tree on the exact same screens, so the device/app is fully introspectable — agent-device's helper just doesn't get it.

A second, independent problem found in the same session — the snapshot-helper instrumentation being left running and locking out the single Android UiAutomation connection — is filed separately (see linked issue).

Environment

Reproduced on two different devices spanning Android 10 → 14 and two OEM skins (LG and Xiaomi), so this is not an old-device / OS-version / OEM-skin artifact:

• 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), LG UX, USB
• Device B: POCO 23049PCD8G (Xiaomi marble), Android 14 (SDK 34), HyperOS, USB
• App: Expo SDK 56, React Native 0.85.3, newArchEnabled=true (Fabric), Hermes, reanimated 4.3.1 (identical app on both)

Problem — snapshot returns only the system window (no app content) on Fabric

On Device A (Android 10, LG):

$ agent-device snapshot -i --platform android
Snapshot: 7 nodes
@e1 [group]
@e2 [image] "Hide navigation bar"
@e3 [image] "Back"
@e4 [group]
@e5 [image] "Home"
@e6 [image] "Overview"
@e7 [group]

snapshot (full) and snapshot --force-full return ~17 nodes — still only system windows (nav bar + an OEM "Tools" overlay), never the app's content.

On Device B (Android 14, Xiaomi/POCO) the same failure occurs, with a slightly different shape:

$ agent-device snapshot -i --platform android
Snapshot: 0 nodes
Interactive snapshot is empty after filtering 44 raw Android nodes.

$ agent-device snapshot --platform android          # and --force-full: identical
Snapshot: 11 nodes        # status-bar icons (wifi/signal/battery/clock) + a Xiaomi "Tools" overlay

i.e. interactive returns 0 (it saw 44 raw nodes and filtered them all out); full returns only the system status bar + OEM overlay — never app content.

For comparison, on the same foreground screen, plain uiautomator returns the full RN tree:

$ adb shell uiautomator dump /sdcard/x.xml      # 19,185 bytes, 58 nodes
UI hierchary dumped to: /sdcard/x.xml
# contains the real app view tree — screen title, section/list headers, button labels,
# bottom-tab labels, etc. (text/content-desc/resource-id/bounds all present)

(Verified across multiple screens: 48 / 58 / 76 app nodes via raw uiautomator dump on Device A; 58 and 61 on Device B.)

Likely cause: the helper is invoked with a very tight idle gate — observed in ps: am instrument -w -e waitForIdleTimeoutMs 500 -e waitForIdleQuietMs 100 -e timeoutMs … SnapshotInstrumentation (matches the android-snapshot-helper README). A Fabric app's accessibility event stream rarely goes quiet for 100 ms within a 500 ms window, so the helper times out and appears to fall back to a non-app window. Raw uiautomator dump uses Android's default (more lenient) idle wait and succeeds on the same screen, which suggests the issue is the helper's idle gate / its window selection on timeout — not accessibility access itself. These idle parameters don't appear to be configurable from the snapshot CLI (--timeout maps to the overall command timeout, not waitForIdleQuietMs).

Minimal reproduction

1. Build/run any RN 0.85 New-Arch (Fabric) Android app; bring a content screen to the foreground.
2. adb shell uiautomator dump /sdcard/x.xml → full app tree (baseline works). (On Android 11+, scoped storage may require /data/local/tmp/x.xml.)
3. agent-device snapshot -i --platform android → only system-window nodes; no app content.

Impact

New Architecture is the default in RN 0.85, so snapshot (and the snapshot → @ref → click flow built on it) is effectively unusable on current RN apps.

[thymikee]

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

Likely next step: make the Android helper path detect a successful-but-system-only capture and fall back to stock uiautomator dump, with a regression fixture for Fabric/system-window-only XML. #851 is related but separate: helper lifecycle/UiAutomation cleanup.