feat(cua-driver-rs)(windows): register autostart task at RunLevel=Highest (unblocks UWP automation, #1602)

[f-trycua]

Summary

Switches the Windows autostart Scheduled Task from RunLevel=Limited to RunLevel=Highest so the daemon runs at the user's elevated token. This is what unblocks cross-AppContainer UIA RPCs (Calculator, modern Settings, Photos, Microsoft Store apps) without requiring UIAccess + EV cert. The installer's -AutoStart path now self-elevates only for the registration step; the rest of the install stays admin-free.

Why now

We isolated the variable on a Windows 11 VM in a 4-cell matrix (DevMode × token IL):

Cell	Result
DevMode OFF + High IL	41 Calculator elements ✅
DevMode ON + High IL	41 Calculator elements ✅
DevMode ON + Medium IL (cuatest, real Medium token confirmed via Win32 GetTokenInformation)	Daemon ran at IL=0x2000, check_permissions.elevated=false; UWP activation blocked by Session 0 (an orthogonal Windows boundary, not the IL boundary)

DevMode toggle does nothing to UIA tree depth. Token integrity is the variable. A real user-session Medium-IL daemon historically returned ~1 Calculator element per #1602 / #1601.

RunLevel=Highest is the cheapest path to the High-IL daemon — one UAC prompt at install time, then silent autostart at every logon. EV cert + UIAccess (full #1602 solution) is still cleaner UX long-term but costs $300/yr + a signing pipeline; this PR removes the Calculator gap today.

Changes

crates/cua-driver/src/autostart.rs

• -RunLevel Limited → -RunLevel Highest in the inline PowerShell Register-ScheduledTask block.
• Detect access-denied / 0x80070005 / "requires elevation" in stderr and emit an actionable error pointing at cua-driver-rs (Windows): ship with uiAccess="true" manifest + signed binary to unblock UWP automation (SendInput / UIA against Calculator-class apps) #1602 instead of the raw stack trace.
• Doc comment expanded with the AppContainer / UIPI rationale.

libs/cua-driver/scripts/install.ps1

• New Test-IsElevated helper using WindowsPrincipal::IsInRole(Administrator).
• Register-CuaDriverAutostart now self-elevates via Start-Process -Verb RunAs when invoked from a non-elevated install, with a clear pre-prompt. The rest of the install (file extraction, junction creation, User PATH update) still runs unelevated.
• Post-install hint block updated for both -AutoStart and non--AutoStart branches — explains RunLevel=Highest, mentions the "Win32 + Chromium fine without; UWP needs autostart" trade-off.

Compat

• Existing users with a cua-driver-serve task at RunLevel=Limited get it re-registered as Highest next time they run cua-driver autostart enable (the registration script unconditionally Unregister-ScheduledTask first).
• Users who never call autostart enable see zero behavior change.
• macOS + Linux paths untouched.

Test plan

• cargo check -p cua-driver clean on the VM (14.56s)
• install.ps1 parses cleanly on PowerShell 5.1 (3,167 tokens, 0 errors)
• End-to-end: irm install.ps1 | iex then cua-driver autostart enable triggers UAC prompt, registers task at RunLevel=Highest, Calculator drives end-to-end after logoff/logon
• Existing Win32 + Chromium tests still pass (no regression at the new IL)

Related

• Closes the practical UWP automation gap in cua-driver-rs (Windows): ship with uiAccess="true" manifest + signed binary to unblock UWP automation (SendInput / UIA against Calculator-class apps) #1602 (cleanest answer is still UIAccess + EV cert; this PR removes the urgency)
• Builds on test-fixtures: consolidate canonical Swift + Rust fixtures into shared dir #1619 (canonical fixtures), cua-driver-rs Windows: launch_app should auto-inject anti-throttling flags for hidden Chromium browsers #1620 (Chromium flag auto-inject), cua-driver-rs Windows: click(x,y) silently rerouted to UIA Invoke when an actionable element is at that point #1621 (UIA Invoke whitelist), cua-driver-rs Windows: PostMessage(WM_LBUTTONDOWN/UP) to Chromium HWND doesn't fire DOM input — coord clicks on Edge/Chrome need SendInput #1623 (SendInput on Chromium) — together these are the v0.2.9+ Windows fix chain

🤖 Generated with Claude Code

Summary by CodeRabbit

• New Features

  • Installation script now automatically requests admin elevation when registering autostart, eliminating the need for manual elevation steps.

• Bug Fixes

  • Enhanced error handling provides clearer guidance when autostart registration requires elevated permissions, directing users to appropriate corrective actions.

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1 Skipped Deployment

Project	Deployment	Actions	Updated (UTC)
docs	Ignored		May 21, 2026 3:24pm

[coderabbitai]

Caution

Review failed

Pull request was closed or merged during review

📝 Walkthrough

Walkthrough

This PR implements elevated Windows scheduled task registration with RunLevel=Highest for UWP/AppContainer automation. The Rust autostart code now detects elevation failures and guides users to re-run elevated; the PowerShell installer self-elevates when necessary and clearly explains the elevation behavior and UWP app requirements.

Changes

Elevated Autostart Task Registration

Layer / File(s)	Summary
Rust autostart: RunLevel=Highest and elevation error handling libs/cua-driver-rs/crates/cua-driver/src/autostart.rs	Generates PowerShell scheduled task registration with RunLevel=Highest instead of Limited. Detects elevation-related PowerShell failures (access denied, Win32 errors, requires elevation) and returns user-facing error guidance to re-run elevated or use install.ps1 -AutoStart, including raw stderr context.
PowerShell install: Self-elevation and user guidance libs/cua-driver/scripts/install.ps1	Adds Test-IsElevated helper. Updates Register-CuaDriverAutostart to run directly when elevated, or spawn an elevated powershell.exe to register when not. Updates messaging to document RunLevel=Highest, explain admin prompt occurrence, and clarify that UWP/AppContainer apps require the elevated task whereas unelevated daemon runs at user integrity level.

Sequence Diagrams

sequenceDiagram
  participant User as User
  participant Installer as install.ps1
  participant ElevCheck as Test-IsElevated
  participant Register as Register-CuaDriverAutostart
  participant ElevPS as Elevated PowerShell
  participant CuaDriver as cua-driver autostart enable
  User->>Installer: Run install.ps1 -AutoStart
  Installer->>ElevCheck: Check elevation status
  alt Already elevated
    ElevCheck-->>Register: IsElevated=true
    Register->>CuaDriver: Run directly
    CuaDriver-->>Register: Task registered with RunLevel=Highest
  else Not elevated
    ElevCheck-->>Register: IsElevated=false
    Register->>ElevPS: Spawn with -Verb RunAs
    ElevPS->>CuaDriver: Run in elevated context
    CuaDriver-->>ElevPS: Task registered with RunLevel=Highest
    ElevPS-->>Register: Propagate exit code
  end
  Register-->>Installer: Registration complete
  Installer-->>User: Display confirmation

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Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

• trycua/cua#1604: Also adjusts Windows autostart elevation and RunLevel handling for uiAccess/UWP automation in both autostart.rs and install.ps1.
• trycua/cua#1550: Introduces the cua-driver autostart enable command that this PR's install.ps1 now delegates to for task registration.

Poem

🐰 A Windows daemon hops up high,
With RunLevel=Highest reaching the sky,
Self-elevating shells now know the way,
UWP apps can autostart and play! ✨

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and specifically describes the primary change: upgrading the Windows autostart task from RunLevel=Limited to RunLevel=Highest to enable UWP automation support.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch feat/cua-driver-rs-autostart-highest-runlevel-for-uwp

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