Windows launcher bundle registers under HKCU despite InstallLauncherAllUsers=1, InstallLauncherAllUsers=1

[sleepy-manul]

Windows Installer: InstallAllUsers=1 InstallLauncherAllUsers=1 still registers bundle under HKCU

Summary

On Windows x64, running the CPython 3.14 installer in quiet mode with:

InstallAllUsers=1 InstallLauncherAllUsers=1 /quiet

installs Python into C:\Program Files\Python314 and installs py.exe into C:\Windows\py.exe (after removing prior per-user launcher state), but the bundle registration still ends up under HKCU (BundleProviderKey=CPython-3.14) instead of HKLM.

This appears to be a Burn bundle scope/registration issue.

Environment

• OS: Windows (x64)
• Version under test: CPython 3.14.3 amd64 installer
• Compared installers:
  • Official/original: C:\TEMP\python-3.14.3-amd64.exe

Repro

1. Ensure Python 3.14 is uninstalled.
2. Remove residual paths:
   • C:\Program Files\Python314
   • %LOCALAPPDATA%\Programs\Python\Python314
   • %LOCALAPPDATA%\Programs\Python\Launcher
3. Run installer elevated:
   • python-3.14.3-amd64.exe InstallAllUsers=1 InstallLauncherAllUsers=1 /quiet /log <bundle.log>
4. Check:
   • Uninstall registration in HKCU vs HKLM
   • Launcher location (C:\Windows\py.exe vs user launcher path)

Actual Behavior (latest run)

• C:\Program Files\Python314\python.exe: present
• C:\Windows\py.exe: present
• %LOCALAPPDATA%\Programs\Python\Launcher\py.exe: absent
• HKCU uninstall entry for CPython-3.14: present
• HKLM uninstall entry for CPython-3.14: absent

Expected Behavior

With InstallAllUsers=1 InstallLauncherAllUsers=1 (and elevated install), bundle registration should be machine-wide (HKLM), not per-user (HKCU).

Key Log Evidence

Installation logfiles include lines showing package scope mismatch against bundle scope:

• Skipping cross-scope dependency registration ... bundle scope: PerUser, package scope: PerMachine

But both runs also apply launcher_AllUsers successfully in the latest comparison:

• Applying execute package: launcher_AllUsers ... ALLUSERS="1" ...

Requested guidance

• Is HKCU bundle registration currently expected for this installer path even with InstallAllUsers=1 InstallLauncherAllUsers=1?
• If not expected, what is the intended Burn authoring mechanism to ensure HKLM bundle registration for all-users installs in this WiX 3.14 setup?

[sleepy-manul]

Actually, the problem is more complicated than I originally thought:

• The behaviour was different on my PC because there was a user-scoped py launcher still present.
• After I removed it, the original Python installed placed py.exe correctly (machine-scoped), so this bug is, technically, not valid anymore.
• However, there is still the problem that bundle registration still ends up under HKCU (BundleProviderKey=CPython-3.14) instead of HKLM, even when passing InstallAllUsers=1 InstallLauncherAllUsers=1. I wasn't able to figure out how to fix that.