fix(cua-driver-rs)(install): rename-out-of-way locked binary before Copy-Item in install-local.ps1

[f-trycua]

Summary

Repro from real user session: re-running `install-local.ps1` while the autostart task has a daemon running fails with:

```
Copy-Item : The process cannot access the file '...cua-driver.exe' because it is being used by another process.
```

Why kill-the-daemon doesn't fix it

The autostart task is `RunLevel=Highest`, so the spawned `cua-driver.exe` runs at High IL. A Medium-IL PowerShell shell cannot terminate a High-IL process — `taskkill /F` and `Stop-Process` both return Access Denied. `schtasks /End` ends the task INSTANCE but the daemon was detached via `Start-Process -WindowStyle Hidden` so it survives.

The only kill paths that work need UAC elevation. Adding a UAC prompt to install-local.ps1 is ugly — interrupts the dev loop every re-build.

Fix: rename-out-of-way

Windows loads .exe images with `FILE_SHARE_DELETE` set, so the directory entry can be renamed while the content stays mapped. `Move-Item` succeeds against a locked .exe; `Copy-Item` then lands at the (now-free) destination path. The renamed-aside file is unlinked at next reboot or when the daemon process exits.

```powershell
if (Test-Path -LiteralPath $DestBinary) {
$stale = "$DestBinary.stale-$((Get-Date).ToString('yyyyMMdd-HHmmss'))"
Move-Item $DestBinary $stale -Force
}
Copy-Item $BuiltBinary $DestBinary -Force
```

Plus a best-effort GC: `.stale-*` siblings older than 1 day get cleaned up so the dir doesn't grow unbounded across many re-builds.

End-to-end verified on Windows

Daemon PID 14152 running (High IL, from `cua-driver autostart kick`):

```
==> renamed locked previous binary to cua-driver.exe.stale-20260524-144036
==> staging into C:\Users\cuademo.cua-driver\packages\releases\0.0.0-local-release-...
```

Post-install:

```
$ ls .cua-driver/packages/releases/0.0.0-local-release-.../
cua-driver.exe ← May 24 14:39 — fresh build
cua-driver.exe.stale-20260524-144036 ← old, still locked by PID 14152
```

Daemon keeps running off the renamed file. New `cua-driver autostart enable` will re-register the task pointing at the fresh `cua-driver.exe`.

If `Move-Item` fails (rare — would require AV/EDR with `FILE_SHARE_NONE`), the script prints a clear hint instead of just dying:

```
Note: could not rename previous binary at .
()
Most likely a running cua-driver daemon is holding it.
Stop it first (e.g. `schtasks /End /TN cua-driver-serve` then re-run).
```

Test plan

• PowerShell parser clean
• End-to-end: install-local.ps1 with a High-IL daemon running succeeds (renames + copies)
• Reviewer: same on a host with no daemon — should still work (the rename branch is gated on `Test-Path`)
• Reviewer: rapid re-builds don't accumulate stale-* files unboundedly (GC older than 1 day)

🤖 Generated with Claude Code

Summary by CodeRabbit

• Bug Fixes
  • Enhanced the local Windows installer's reliability during updates. The installer now safely handles cases where the previous version's binary is still executing by renaming existing locked executable files and automatically cleaning up older installation artifacts from prior updates. This enables more robust and reliable updates even when the prior version is still running.

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

1 Skipped Deployment

Project	Deployment	Actions	Updated (UTC)
docs	Ignored		May 24, 2026 2:42pm

[coderabbitai]

Caution

Review failed

Pull request was closed or merged during review

📝 Walkthrough

Walkthrough

The Windows local installer script enhances binary staging to handle locked executables. When the destination contains an existing cua-driver.exe, the script now renames it to a timestamped .stale-* filename, cleans up older stale binaries (older than 1 day), and then stages the new binary.

Changes

Guarded Binary Staging

Layer / File(s)	Summary
Locked binary detection, rename, and stale cleanup libs/cua-driver/scripts/install-local.ps1	Script detects a pre-existing DestBinary in the versioned directory, renames it to a timestamped .stale-* name with warning output on rename failure, removes older stale binaries (>1 day old), and then stages the newly built executable to the validated path.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related PRs

• trycua/cua#1658: Both PRs modify the Windows local installer script to adjust destination binary handling during installation staging.

Poem

🐰 A rabbit once dreamed of an install so clean,
Where locked binaries wouldn't muck up the scene—
Rename to stale, sweep the old ones away,
Then stage the new binary, fresh as the day! ✨

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately and specifically describes the main change: renaming a locked binary before copying in the Windows installer script, addressing the core problem of file-in-use errors.
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.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch install-local-stop-daemon-first

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands and usage tips.}