Detect Squirrel / Electron auto-updater apps (%LocalAppData%\<Vendor>\<App>\Update.exe --uninstall)

[chirag127]

Summary

A large class of modern Windows apps installs into %LocalAppData% (per-user, no admin) via the Squirrel installer or an Electron auto-updater. Examples: Slack (older builds), Discord, GitHub Desktop, Atom-heritage tools, several Electron apps, and Microsoft Teams classic.

Uninstall for these is not a normal MSI or NSIS invocation — it is:

%LocalAppData%\<Vendor>\<App>\Update.exe --uninstall -s

BCU sees these in HKCU\Software\Microsoft\Windows\CurrentVersion\Uninstall\<key> with a QuietUninstallString pointing at Update.exe, but:

1. The UninstallerKind classification is not "Squirrel" — it falls through to a generic bucket.
2. Junk detection does not look under %LocalAppData%\<Vendor>\<App>\packages\<version> and %LocalAppData%\<Vendor>\<App>\SquirrelSetup.log, both of which routinely survive.
3. %LocalAppData%\<Vendor>\<App>\Update.exe and any shortcut in %AppData%\Microsoft\Windows\Start Menu\Programs\<Vendor> also survive.

Proposal

• Add a Squirrel value to UninstallerKind (analogous to Msiexec, Nsis, InnoSetup, Scoop, …) so users can filter for these separately.
• Detection heuristic: QuietUninstallString matches %LocalAppData%\**\Update.exe --uninstall*, OR the install location contains \packages�pp-<semver>\ alongside a top-level Update.exe and SquirrelSetup.log.
• Junk scan: when an app is classified Squirrel, add its full %LocalAppData%\<Vendor>\<App>\ directory as a high-confidence leftover candidate after uninstall completes.

Related

• WindowsApps (Microsoft Store) #560 open — WindowsApps/MSIX leftovers (adjacent category, MSIX-specific)
• Logitech G Hub uninstallation does not detect leftover files #445 open — Logitech G Hub leftover detection (adjacent; not Squirrel but same "modern per-user install" pain)

No prior issue mentions Squirrel by name.

Version

BCU v6.2.0.0 on Windows 11. Verified with Discord + GitHub Desktop installed via their normal installers.