[cryptotavares]

Description

Mobile observations carried noise and made more device calls than needed:

• Android status bar: on Android the status bar is a separate top-level window with 22 com.android.systemui:* ids. The clock, signal and battery change between snapshots, so they made up most of the 35 login testIds, and unchanged screens never produced an empty diff.
• Expo dev menu button: the button (gearshape.fill + "Tools") showed up as an app element on both platforms.
• Window size: every testId read made an extra getWindowSize() device call for the visibility check.

Changes:

• filterAppHierarchy (new src/platform/mobile-hierarchy.ts) runs once per snapshot. The a11y tree, testIds and generate_locators are all built from its output, so they agree.
  • Android: a top-level window is dropped only if it is shaped like a bar (full width or full height, at most 15 % thick) and all its ids are com.android.systemui:*. That covers the status bar and nav bar. Other system windows (biometric prompt, consent and permission dialogs, keyboard) stay. In a flat hierarchy, only status/nav bar ids are dropped.
  • Both platforms: the Expo dev menu button is dropped. The new MobilePlatformDriver option excludeDevOverlay (default true; type MobilePlatformDriverOptions is exported) turns this off.
• Viewport from the snapshot: iOS uses the root frame and Android the extent of the top-level windows. getWindowSize() is now only a cached fallback.
• Mobile settle:
  • the time budget now includes the first capture;
  • an unchanged screen is not captured again when the first capture already took ≥ 1 s (MOBILE_SETTLE_SLOW_CAPTURE_MS); on Android one capture is an am instrument run;
  • busy screens still retry.
• Tests confirm that observations, describe_screen, list_testids and accessibility_snapshot take one snapshot each (P1-08's captureScreen).

Part of the mm CLI v2 effort: ticket P1-13 (Phase 1).
Stacked on #66 (review that first).

Breaking changes

None. The constructor option is optional. Mobile testIds and trees no longer contain Android status/nav bar windows or the Expo dev menu button.

Consumer impact

Consumer	Change needed	Done on branch
Extension test/e2e/playwright/llm-workflow/	None (mobile only)	n/a
Mobile tests/llm-workflow/	None. Its agent-device snapshot output on Android (pixel frames, full resource-ids) is handled.	n/a

Proof

Tested with yalc builds in Mobile (dev client) on the iOS simulator and the Android emulator. Before = #66 build, after = this branch. Click and benchmark rows are 5 runs each; host load was 5–14.

Check	Before (#66)	After (3cc8aa9)
Android login testIds / com.android.systemui	35 / 22	13 / 0
Android wallet describe-screen root windows / systemui nodes	2 / 22	1 / 0
Android generate-locators on login	–	13 locators, 0 systemui, 0 dev menu
Android click observationMs p50 / p95	963 / 1048	891 / 914 (−7 % / −13 %)
Android unchanged-screen click: empty diffs	0 of 5	1–2 of 5 (7.8 KB)
iOS login testIds	10 (incl. gearshape.fill)	9
iOS click observationMs p50 / p95	1170 / 1232	972 / 1005 (−17 %)
iOS list-testids / describe-screen toolMs p50	1162 / 1516	895 / 1284
iOS idb describe (window size) per click / describe / list	5 / 2 / 2	4 / 1 / 1
Device snapshots per click / describe / list (both platforms)	3 / 1 / 1	3 / 1 / 1

AC3 ("Android click observationMs roughly halves") is not met, and core cannot meet it.

• Halving assumed 2 snapshots per observation. P1-08 already brought that down to 1.
• Each click takes 3 device snapshots: 2 inside the backend tap (waitForElement + tapElement, in device-mcp / the Mobile agent-device helper) and 1 for the observation.
• Removing the tap's snapshots needs a change in device-mcp or the consumer, for example tapping at coordinates already in the last observation. That is listed as a follow-up.

Still noisy on Android:

• Some unchanged-screen diffs are still 30–135 KB, because the app keeps mounting zero-height ViewGroups. P1-14 (drop layout-only nodes) covers this.
• On iOS, 2–4 full-screen Toolbar / FloatingBarHostingView nodes remain. They are most likely UIKit's floating bar per navigation controller, not the dev launcher. They are kept for now, pending a check on a release build.

Unit tests

Test Files  52 passed (52)
     Tests  1723 passed (1723)
Type Errors no errors
All files | 97.49 | 94.79 | 96.69 | 97.63
yarn lint → exit 0

New tests:

• mobile-hierarchy.test.ts:
  • bar-window rule, plus a biometric prompt window that is kept;
  • flat-hierarchy fallback, dev overlay and the excludeDevOverlay option, empty-container pruning;
  • viewport from the root frame or Android extent, including an off-origin window and a status-bar-only snapshot;
  • a real Android login snapshot fixture (src/platform/__fixtures__/, excluded from the build), which reduces to 1 root and 0 systemui testIds.
• Driver: 1 snapshot per call, getWindowSize at most once, generateLocators filtered.
• Server: 1 snapshot per observation; the settle budget includes the first capture; slow first capture → no unchanged-screen retry, busy screens still retry.