[Timo972]

Fixes DROID-305 (droidrun/mobilerun#484): mobilerun device ui --ios hangs on an iPhone X / iOS 16.7 with TikTok, and on the Home Screen after that.

Cause

GET /mobilerun/state took its snapshot through XCTest (snapshotWithError:). XCTest waits up to its 60s accessibility timeout per request and retries on top of that ("Find the Application … (retry N)"). The reporter's debug log shows WDA silent for 61s on a single TikTok snapshot request.

WDA handles one request at a time, so every later request queued behind the stuck snapshot. That includes requests made after going back to the Home Screen. mobilerun-ios hit its 60s deadline (and its recovery probe did too), and the CLI timed out after 30s on each of its 7 attempts.

Change

• Snapshots are requested directly (FBXCAXClientProxy), without XCTest's resolution retries, under a temporary accessibility timeout.
  • 10s for the full tree.
  • Then 5s for a shallow tree: 15 levels, 20 children per element.
  • The timeout is global to the runner, so it is restored right after each snapshot. A test covers that.
• If neither snapshot finishes, the state still names the foreground app (phone_state.packageName). The app is detected without a snapshot, and the app root alone serves as the tree. Released mobilerun-ios rejects a null tree and drops a mostly off-screen childless root, so the root spans a square covering the screen in either orientation.
• New top-level truncated field. Released mobilerun-ios ignores it.
• The route always answers 200, so a failed snapshot can no longer surface as an error (the 404 latch from fix(mobilerun): keep a failed state snapshot from answering 404 #38 is moot here).
• Kept: when the snapshot fails because another app took over (Home press race), that app is snapshotted in full.

Verification

• Simulator, iOS 27, IntegrationApp's "Deadlock app" (main thread asleep for 20s):
  • Before: the state snapshot waits until the app unfreezes (19.9s; on device this is up to 60s per try).
  • After: answers in 15.03s with truncated: true and the right packageName.
  • A normal app still gets the full tree in 0.01s, with labels, types and bounds.
• Restore test (testSnapshotTimeoutDoesNotOutliveTheSnapshot): fails with the restore disabled (a later snapshot gave up after 1.01s), passes with it in place.
• UnitTests 256/256 (1 skipped). FBMobilerunA11yIntegrationTests and FBMobilerunActionsIntegrationTests 7/7. tvOS lib builds.
• The frozen-app integration tests skip on CI, like the existing accessibilityDeadline test.

Real device: iPhone XR, iOS 18.7.7, TikTok 45.7

Installed through mobilerun-ios setup --reinstall --wda-unsigned-url … (ASC signing), the same path users take.

Reproduced the hang on iOS 18. Right after a cold start, TikTok stops answering accessibility requests ("Error getting main window kAXErrorIPCTimeout") for minutes.

With this PR:

• GET /mobilerun/state answers in 15.1s every time. The full snapshot gives up at 10s, the shallow one at 5s, and the answer is root-only with packageName: com.zhiliaoapp.musically and truncated: true.
• Through mobilerun-ios /state_full it takes 15.1–18.8s. The extra time is spent in the portal, not in WDA.
• Home Screen with TikTok stuck in the background: 0.39–0.45s.
• mobilerun device ui --ios (mobilerun 0.6.20) with TikTok in front and stuck: returns in 16.5s with TikTok's package name and no retries.
• Responsive TikTok (feed loaded, plus 5 swipes) and the Home Screen: 0.29–0.48s, full tree (142 TikTok nodes), truncated: false. Same speed as the old runner (0.31–0.75s).

Bug found on the device and fixed in f7e4623: the root-only fallback was sized from the runner's UIScreen, which on a device is the letterboxed 320×480 compatibility screen, so it came out 480×480. nativeBounds is scaled the same way. It now uses SpringBoard's frame (depth-1 snapshot, 2s limit), which gives 896×896 on the XR. The simulator can't show this, because the runner isn't letterboxed there.

Still unverified: iOS 16 (the reporter's iPhone X). If _setAXTimeout fails there, WDA logs it and falls back to the old, unbounded behavior. A preview build goes to the reporter.

Follow-ups (other repos)

• mobilerun-ios: keep its WDA state deadline below the CLI's 30s, and read truncated.
• mobilerun CLI: don't retry 7× on ReadTimeout.

🤖 Generated with Claude Code