Complete #147, #152, #153 - the partial fixes from 0.74.0

[sanderdewit]

0.74.0 closed #147, #152 and #153 only partially. This finishes all three.

#147 — security, without requiring admin

The bypass hardening in 0.74.0 leaned on a machine-scoped environment variable, which would have left a non-admin on an air-gapped agent stuck. The module must never require elevation — that is the whole reason it parses hives through offreg.dll instead of reg.exe load, which demands SeBackupPrivilege/SeRestorePrivilege.

• New Set-MsixToolVerification -Enabled $false — session-scoped, in-memory, no admin rights. This is the supported escape hatch for offline agents.
• A process/user-scoped MSIX_SKIP_TOOL_VERIFICATION is now ignored (with a Warning pointing at the cmdlet). That is the actual attack: a non-admin persists it in HKCU\Environment and every future session silently trusts an arbitrary tools root. Machine scope is still honoured for fleet config — reading it needs no admin, only writing does.
• Resolve-MsixProcMonPath / Resolve-MsixDebugViewPath now Authenticode-verify every candidate before returning it. ProcMon loads a kernel driver so it runs elevated, and the resolver trusted a user-settable override plus a fixed C:\PSF\ProcessMonitor\Procmon.exe fallback — a directory any standard user can create, since the root of C: grants Authenticated Users CreateDirectories. Local privilege escalation. Untrusted candidates are skipped, not fatal, so a poisoned override cannot deny service either.

Verified unelevated: session opt-out works, a planted unsigned ProcMon is refused, a genuinely signed binary is accepted, and the only reg.exe/privilege references left in the codebase are the comments explaining why offreg is used.

#153 — correctness

• _MsixOfflineSaveHive return no longer discarded — a failed save shipped a signed modification package with none of the requested registry keys, exit code 0, and a log line claiming success.
• Idempotency guards for Add-MsixFileTypeAssociation, Add-MsixShellVerbExtension, Add-MsixFileExplorerContextMenu, and the Rule element of Add-MsixFirewallRule.
• The rest of the @($null) cluster — 15 sites across 15 files.
• -CaptureTrace now works: it called Invoke-MsixProcMonCapture -PackagePath, not a parameter of that cmdlet, inside a catch that logged and continued — so the feature had never produced a .pml.
• Test-MsixSignature now includes NotTrusted in NeedsSelfSign.
• Add-MsixVcRuntimeBundle no longer coerces an undetectable/arm64 architecture to x86 while logging "auto-detected", and no longer packs a partial bundle as success.
• Write-MsixLog writes UTF-8 with -LiteralPath (ANSI on 5.1 turned → into a literal ?; -Path treated [ ] as wildcards and dropped the line).

#152 — coverage

• Never-invoked exported functions: 73 → 26. All 26 remaining are genuinely environment-bound (network installers, Hyper-V/VHDX, ProcMon's kernel driver, Windows Sandbox, a live installed package) and each is listed with its reason.
• The ratchet now guards the whole exported surface, not just Add/Remove/Set/Update — the narrow scope is exactly how 73 functions went uncovered with nothing reporting it. Three orchestrators are recorded as real debt with a ceiling so the list can only shrink.
• Authenticode rejection is tested for the first time. Both prior tests mocked Get-AuthenticodeSignature to return Valid, so the throw branch — the control that stops a planted toolchain binary from executing — had never run. Every rejection reason is now driven, plus a valid-signature-but-untrusted-publisher case and a positive control.
• Read-only scanner matrix: all 15 scanners against a well-formed package, against the degenerate manifest the module itself generates, and against a missing package (must fail loudly, not return a clean-looking empty result). Explicit named invocations back the matrix so coverage is AST-visible rather than trusting strings again.
• Code coverage measured in CI and reported in the job summary — there was none before.
• Fixed test isolation: the update-check tests wrote to the real user cache, poisoning it with a mocked version and producing a false "1.0.0 is available" notice.

Validation

• Full suite green, PSSA clean at ParseError/Error/Warning.
• Verified unelevated throughout — no new admin requirement anywhere.

🤖 Generated with Claude Code