Three observability fixes that made the VC++ MSI failures actually
debuggable instead of showing "Exit code - FAILED" with an empty
value for every install:
1. Switch from Start-Process -PassThru (without -Wait) to
[System.Diagnostics.Process]::Start() with a ProcessStartInfo.
PowerShell 5.1 has a known bug where Start-Process disposes the
Process object's OS handle when control returns to the script,
so $proc.ExitCode reads as $null even after WaitForExit() - which
was causing every MSI install to be reported as failed regardless
of the actual result.
2. Pass /L*v <log> to msiexec on every MSI install so we get a full
verbose log per app at C:\Logs\PreInstall\msi-<safename>.log.
3. On install failure, scan the verbose log for *meaningful* lines
(Note: 1: <code>, "return value 3", custom action errors, "Failed
to", "Installation failed", common 2xxx error codes) instead of
tailing the last 25 lines, which is rollback/cleanup noise. This
surfaces the actual root-cause line directly in the runner log so
you don't have to dig through C:\Logs to diagnose.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
564f14ffcf