[greyhair-atx (greyhair-atx)]

📖 Description

Resolve MSI installation scope using Windows Installer context instead of inferring it solely from the ARP registry hive. A user-unmanaged MSI can appear under HKLM, causing WinGet to reject --scope user or select a machine installer during an unscoped upgrade.

Enumerate current-user and machine registrations once per inventory helper, cache case-insensitive ProductCode/context mappings, and filter both ARP hives by the resolved scope. Preserve hive-based behavior for non-MSI entries. Missing/ambiguous MSI context and enumeration errors fail closed by omitting affected MSI inventory rather than guessing a scope. This conservative inventory change deserves particular review; it does not repair MSI transaction rollback.

🔗 References

Addresses #3011. Reproduction and published installer identities: #3011 (comment).

🔍 Validation

• Release x64 targeted CLI and AppInstallerCLITests builds on base c608376; full-solution build not completed (unrelated DesktopBridge/E2E restore issues). Local build used SpectreMitigation=false because the relevant libraries were unavailable; NuGet advisory warnings were not treated as errors. These are test binaries, not distribution builds.
• Selection [msiscope],[arphelper],[manifest_comparator],[installed]: 45 cases / 1,521 assertions locally; 45 / 1,289 on the Windows 11 disposable VM's standard-user interactive session. Local selection repeated successfully before submission.
• New cases cover managed/unmanaged/machine contexts, current-user-only enumeration, case folding, sticky ambiguity, short SID-buffer retry, partial enumeration failure, non-MSI retention, and user/machine source filtering across ARP hives.
• VM REST 1.4 catalog: eight successful package-specific upgrades covering user/machine, explicit/unscoped commands, and latest-only/both-version metadata. Verified native context, signed executable/hash, settings and final uninstall. A ninth incompatible-scope scenario rejected before removing the old user MSI.
• Not tested: production publishing/preindexed catalog, upgrade --all, all supported Windows releases, or general installer failure recovery. Separate forced-failure MSI tests did not restore complete registration; this PR makes no rollback-safety claim.

✅ Checklist

• Signed the Contributor License Agreement
• Linked to an issue
• Added a release note fragment
• Updated documentation (release note)
• Added tests
• Updated Copilot instructions (no build/architecture/convention changes)

🤖 AI Assistance

• AI assistance was used and has been disclosed in this PR
• No AI assistance was used

AI assistance contributed the implementation, regression tests, disposable-VM test orchestration and this description. The contributor remains responsible for review and validation.

📋 Issue Type

• Bug fix
• Feature
• Task

Microsoft Reviewers: Open in CodeFlow

Spelling follow-up: commit b7de1ab acknowledges five Windows Installer API/test terms in the existing dictionary. Executable code is unchanged. The CLA and spelling checks passed; native Azure Pipelines validation still awaits an authorized upstream maintainer.

[azure-pipelines]

Azure Pipelines:
There may be pipelines that require an authorized user to comment /azp run to run.