test(android): prepare the snapshot helper before landmark waits

[thymikee]

Summary

• Prepare the Android snapshot helper with a required public CLI snapshot before each scenario's landmark wait. Cold helper installation and UiAutomation recovery no longer consume the app's 10-second observation window.
• Keep the existing wait deadline and propagate failed preflights. No runtime behavior, retries or fallback policy changes.
• Two files, +65/-0: test harness +3, evidence +62; production +0/-0. Fixes Android smoke: first fixture capture stalls before any readable snapshot #3831's smoke preparation boundary, without claiming to repair Android framework initialization.

Validation

• Tested 62b5c078d171956d2658dd8808959be60c345ca3: pnpm check:affected --run --head 62b5c078d1 passed five checks, exactCommit=true, checkoutChanged=false; one device gate skipped, not passed. Independent review: no findings.
• Real Android 16 arm64 smoke: all seven scenario groups passed in 42.3s after rebasing onto perf(android): reuse live helper for input and capture #3811/perf(android): bound target readiness and confirm moved clears #3815. One earlier run lost ADB; its failure and recovered repeat are retained. Focused harness/coverage tests: 25 passed.
• Injected 10.2s cold installation: original sequence fails with wait_capture_stalled; preflight sequence passes. Missing landmarks still fail at 10s; an unavailable helper fails before the wait. Evidence.
• Hosted Android x86_64, Apple and Linux smoke, Coverage, Integration and Repo Guards passed at 62b5c078d1. The cache build matrix was skipped; automated review is neutral. The framework connection timeout itself remains outside this fix.

[github-actions]

Size Report

Metric	Base	Current	Diff
Installed (including dependencies)	5.45 MB	5.45 MB	0 B
Package (unpacked)	5.45 MB	5.45 MB	0 B
Package (download)	1.65 MB	1.65 MB	-11 B

Startup median (7 runs, lower is better):

Scenario	Base	Current	Diff
CLI --version	43.2 ms	45.6 ms	+2.4 ms
CLI --help	84.1 ms	87.1 ms	+2.9 ms

[thymikee]

This PR is ready at 62b5c07. The change looks correct, and all 16 checks pass, including the hosted Android smoke run at this head. I know of no conflicts, and nothing else stands in the way of merge. Not blocking: the 62-line evidence doc cites local logs that readers cannot open later, so keep it only if the repo keeps docs/evidence files, and the android-helper backend assert in https://github.com/callstack/agent-device/blob/62b5c07/test/integration/android-emulator-e2e/scenario-start.ts#L28 also fails on a one-shot or fallback capture, which fits the goal of not hiding helper failures; take or leave both. The hosted result is one run, and the framework UiAutomation timeout is not fixed, so a flake can now surface in the preflight itself. I did not inspect the local logs.

[github-actions]

PR Preview Action v1.8.1
Preview removed because the pull request was closed.
2026-10-20 07:16 UTC