docs(skills): document one-shot observe CLI workflows

[quanruzhuoxiu]

Summary

• document the one-shot observe command for the browser, Android, iOS, HarmonyOS, and computer skills
• explain when to use observe instead of a current-state assert
• include platform-specific connection, device, and continuous-frame-source guidance
• update each skill workflow so transient UI verification stays within one CLI invocation

Motivation

Transient UI such as toasts, banners, animations, and screen transitions may disappear before a separate assert command runs. These updates teach agents to use the new one-shot CLI observation workflow introduced by web-infra-dev/midscene#2848.

Impact

Agents can verify transient UI without attempting to split startObserving and stop across stateless CLI processes. Ordinary assert remains the recommended command for current or final screen state.

Validation

• git diff --check
• verified the frontmatter and command examples in all five modified skill files
• validated the underlying Web CLI against the transient-toast fixture with --interval-ms 200, --max-frames 30, and --watchdog-ms 15000; the observed-window assertion passed

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: 22e7955511

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".

[chatgpt-codex-connector]

Delay documenting unreleased observe command

This and the equivalent blocks added to the Android/iOS/HarmonyOS/computer skills point agents at @midscene/*@1 observe, but the supporting Midscene change is not in a released @1 package yet: I checked the referenced upstream PR web-infra-dev/midscene#2848 and it is still open, while current Midscene main only registers the common CLI tools take_screenshot, act, and assert. If these skill docs are published before that CLI release, any transient-UI workflow will choose observe and fail with an unknown command; please gate this guidance on the release or pin it to a version that contains the command.

Useful? React with 👍 / 👎.