fix(install): skip Microsoft Store python.exe stub in Test-Python fallback (#24424)

[briandevans]

Summary

• Fresh Windows 11 installs of Hermes fail at the python-detection step because the installer invokes the Microsoft Store app-execution alias at %LOCALAPPDATA%\Microsoft\WindowsApps\python.exe, which isn't a real interpreter.
• The stub's "Python was not found..." message bubbles up through $ErrorActionPreference = 'Stop' and replaces the script's friendlier error.
• Fix: detect the alias by path, skip it in the fallback, and surface a one-line pointer to the Windows toggle when it's the only python.exe on PATH.

The bug

scripts/install.ps1 runs Test-Python with three fallback layers:

1. uv python find 3.11
2. uv python install 3.11 then re-find
3. uv python find 3.12 / 3.13 / 3.10
4. System-Python fallback — Get-Command python then python --version

On a clean Windows 11, layer 4 picks up the Store app-execution alias, which prints

Python was not found; run without arguments to install from the Microsoft Store, or disable this shortcut from Settings > Apps > Advanced app settings > App execution aliases.

and exits non-zero. With $ErrorActionPreference = 'Stop' set at the top of the script, the NativeCommandError replaces the script's own throw, surfacing to the user as

✗ Installation failed: Python was not found...

The reporter's transcript in #24424 shows this exact sequence — uv python install 3.11 failed with a flaky download, the secondary uv python find for 3.10/3.12/3.13 also found nothing, and the bare python fallback hit the Store stub.

The fix

In Test-Python (scripts/install.ps1):

• Capture Get-Command python -ErrorAction SilentlyContinue into $pythonCmd.
• Skip when $pythonCmd.Source -match '\WindowsApps\' — that's the Store alias directory.
• Invoke & $pythonCmd.Source --version via the resolved path inside a try/catch so a broken interpreter can't terminate the script through Stop preference.
• When the alias is the only python.exe on PATH, add a short pointer to the toggle location (Settings > Apps > Advanced app settings > App execution aliases) before the existing "install Python 3.11 manually" guidance, so the user doesn't have to copy the path out of the error message and search for it.

No behavior change when the user has a real python.exe on PATH — the regex '\\WindowsApps\\' only matches the Store alias's install path.

Test plan

• Focused regression test: tests/tools/test_windows_native_support.py::TestInstallPs1SkipsStorePythonStub — source-level lint that the install.ps1 contains the WindowsApps skip guard and invokes $pythonCmd.Source --version rather than bare python. Runs on Linux CI; no Windows runner needed.
• Adjacent suite: full tests/tools/test_windows_native_support.py (60 tests) passes locally — no collateral damage to the existing source-level lints.
• Regression guard: the new tests assert presence of strings only introduced in this PR ("WindowsApps", "$pythonCmd.Source --version"); reverting scripts/install.ps1 causes both assertions to fail with the precise scope they're meant to protect.

Related

• Fixes [Bug]: Windows native installation fails if python not installed #24424

[Copilot]

Pull request overview

This PR improves the Windows PowerShell installer’s Python detection by avoiding the Microsoft Store python.exe app-execution alias (the %LOCALAPPDATA%\Microsoft\WindowsApps\python.exe stub) so fresh Windows 11 installs don’t fail with the stub’s “Python was not found…” message overriding the installer’s own error handling.

Changes:

• Updates Test-Python in scripts/install.ps1 to resolve python via Get-Command, skip the WindowsApps alias, and invoke the resolved command path inside try/catch.
• Adds a targeted source-level regression test to ensure the WindowsApps guard and resolved-path invocation remain present.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
scripts/install.ps1	Adds WindowsApps alias detection/skip and safer resolved-path invocation for python --version, plus clearer guidance when only the alias is present.
tests/tools/test_windows_native_support.py	Adds a regression test that lints install.ps1 source for the WindowsApps guard and resolved-path invocation marker.

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[briandevans]

@copilot All findings addressed in commit 0dd36e5:

• scripts/install.ps1 — narrowed the alias guard from -notmatch '\WindowsApps\' to -notmatch '\Microsoft\WindowsApps\' on both the skip branch and the hint branch, so a legitimate python.exe that happens to live under any other WindowsApps directory is no longer also skipped.
• tests/tools/test_windows_native_support.py — replaced the bare "WindowsApps" in source substring assertion with a guard-expression assertion ($pythonCmd.Source -notmatch '\Microsoft\WindowsApps\') so a regression that removes the actual check (leaving only the comment) fails loudly. Added a parallel test for the match-branch hint.

[briandevans]

Closing — superseded by @teknium1's #26586 which landed on main (commit 622c27e) and covers the same Microsoft Store stub skip in install.ps1's Test-Python fallback. Happy to reopen if there's a remaining gap I missed.