[kerdofficial]

What changed

• On Windows, the updater and its test call %SystemRoot%\System32\tar.exe by absolute path instead of looking tar up on PATH.
• The PowerShell installer tests start powershell.exe without the inherited PSModulePath.

Why

The Windows CI guest now runs steps in PowerShell 7 (pwsh); on main in run 38669251591 (2026-10-15) every step used Windows PowerShell. Since then two things fail on every PR, including ones that do not touch these files:

• update.test.ts fails with tar: Cannot connect to C: resolve failed, because a GNU tar is now found first on PATH. The updater has the same exposure on users' machines. Windows release archives are zip files that only the system bsdtar extracts, and an updater should not run whatever tar comes first on PATH.
• install-windows.test.mjs fails with Get-FileHash is not recognized. PowerShell 7 exports its own module path, and a child Windows PowerShell 5.1 then cannot load its built-in cmdlets.

The installer itself is unchanged.

Checklist

• The PR title follows conventional commits
• The PR does one thing
• pnpm check passes locally
• Every affected surface is covered (updater, installer tests)

Proof: this PR's Windows job, where the first commit already turned pnpm check green.