fix(v3/windows): don't fatal on GetCursorPos failure (locked/secure desktop)

[wayneforrest]

Problem

On Windows, w32.GetAllScreens() queries GetCursorPos (only to set the cosmetic Screen.IsCurrent flag) and treats a failure as a hard error:

ret, _, _ := procGetCursorPos.Call(uintptr(unsafe.Pointer(&cursor)))
if ret == 0 {
    return nil, fmt.Errorf("GetCursorPos failed")
}

GetCursorPos returns FALSE / ERROR_ACCESS_DENIED whenever the calling process is not attached to the interactive input desktop — the workstation is locked, on the secure/UAC desktop, or mid session switch (logon, RDP, fast-user-switch).

At startup this is fatal. processAndCacheScreens() runs during App.Run() (via newPlatformApp) and turns the error into os.Exit(1):

err = result.processAndCacheScreens()
if err != nil {
    app.handleFatalError(err) // -> os.Exit(1)
}

So an app launched onto a non-interactive desktop dies before it ever shows, printing the "catastrophic failure … GetCursorPos failed" banner. This is reproducible for packaged/MSIX apps registered as a StartupTask (the shell launches them at logon, before the session's input desktop is switched away from Winlogon), and for background-update restarts that land while the machine is locked. We hit it in the field on a Microsoft Store build.

Fix

The cursor position is used only to compute IsCurrent (which monitor the pointer is on), and that field has no readers — it isn't even propagated to the application-level Screen. So a failed query should degrade gracefully instead of aborting:

• GetAllScreens now reads the cursor through a small package seam and, when it fails, leaves IsCurrent = false and keeps enumerating. The flag self-corrects on the next WM_DISPLAYCHANGE / SPI_SETWORKAREA re-cache, which already handles errors non-fatally via handleError.
• Win32Menu.ShowAtCursor() had the same globalApplication.fatal("GetCursorPos failed"). A context menu simply cannot be shown on a non-input desktop, so it now returns (with a debug log) — matching the already-graceful windowsMenu.ShowAtCursor(), which does if !ok { return }.

A Windows regression test overrides the seam to simulate the failure and asserts GetAllScreens no longer returns a cursor error and marks no screen current.

Notes

• Behaviour-preserving on the happy path; no public API change.
• The two spots were inconsistent before this: windowsMenu.ShowAtCursor() already tolerated the failure while Win32Menu.ShowAtCursor() and GetAllScreens() treated it as fatal.

🤖 Generated with Claude Code

Summary by CodeRabbit

• Bug Fixes

  • Prevented cursor-position errors from crashing the application when opening popup menus.
  • Improved screen detection reliability when the cursor position cannot be retrieved.
  • The app now continues operating without incorrectly marking a screen as current when cursor information is unavailable.

• Tests

  • Added coverage for cursor-position failures during popup menu and screen handling.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: e60de67f-8867-4fa0-8831-95d348bf0396

📥 Commits

Reviewing files that changed from the base of the PR and between 107e42c and 9cece36.

📒 Files selected for processing (3)

• v3/pkg/application/popupmenu_windows.go
• v3/pkg/w32/screen.go
• v3/pkg/w32/screen_cursorfail_test.go

---

Walkthrough

Cursor-position failures on Windows are now handled gracefully. Popup menus log and return instead of terminating, while screen enumeration continues without marking a current monitor when the cursor location is unavailable. Windows-only tests cover both behaviors and the default cursor-position seam.

Changes

Cursor Failure Handling

Layer / File(s)	Summary
Graceful screen enumeration v3/pkg/w32/screen.go, v3/pkg/w32/screen_cursorfail_test.go	Screen enumeration tolerates cursor-position failure, leaves all screens non-current when the position is unknown, and adds Windows-only regression and seam tests.
Nonfatal popup positioning v3/pkg/application/popupmenu_windows.go	ShowAtCursor logs cursor-position failure and returns without terminating the application.

Estimated code review effort: 2 (Simple) | ~10 minutes

Poem

I’m a rabbit with a menu to show,
But lost cursor paths can make it slow.
Screens still count, no crash in sight,
No monitor claims the missing light.
Hop, hop—graceful handling done! 🐇

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly summarizes the main Windows fix: handling GetCursorPos failures without fatal errors.
Description check	✅ Passed	The description covers the problem, fix, motivation, and testing, with only template sections like issue reference and checklists missing.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
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.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

Warning

There were issues while running some tools. Please review the errors and either fix the tool's configuration or disable the tool if it's a critical failure.

🔧 golangci-lint (2.12.2)

level=error msg="[linters_context] typechecking error: pattern ./...: directory prefix . does not contain modules listed in go.work or their selected dependencies"

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[wayneforrest]

cc @leaanthony @atterpac

One more PR - then my app will be crash free.