fix(desktop): skip empty shared install scans

desktop/build/recover-legacy-install-data.ps1

@@ -636,7 +636,7 @@ function Write-AppModeAtomically {
 function Invoke-LegacyRecovery {
   param(
     [Parameter(Mandatory = $true)][string[]]$InstallDirs,
-    [string[]]$SharedInstallDirs = @(),
+    [AllowEmptyCollection()][AllowEmptyString()][string[]]$SharedInstallDirs = @(),
     [Parameter(Mandatory = $true)][string]$UserDataDir,
     [Parameter(Mandatory = $true)][string]$RecoveryRoot,
     [Parameter(Mandatory = $true)][string]$ProcessName,
@@ -657,8 +657,12 @@ function Invoke-LegacyRecovery {
     -UserDataDir $UserDataDir `
     -ActiveConfigDir $ActiveConfigDir `
     -ActiveConfigManaged $ActiveConfigManaged
-  $potentialSharedInstallDirs = @(Get-PotentialInstallDirs -InstallDirs $SharedInstallDirs)
-  $existingSharedInstallDirs = @(Get-ExistingInstallDirs -InstallDirs $potentialSharedInstallDirs)
+  $sharedInstallDirInputs = @($SharedInstallDirs | Where-Object { -not [string]::IsNullOrWhiteSpace($_) })
+  $existingSharedInstallDirs = @()
+  if ($sharedInstallDirInputs.Count -gt 0) {
+    $potentialSharedInstallDirs = @(Get-PotentialInstallDirs -InstallDirs $sharedInstallDirInputs)
+    $existingSharedInstallDirs = @(Get-ExistingInstallDirs -InstallDirs $potentialSharedInstallDirs)
+  }
   if ($existingSharedInstallDirs.Count -gt 0) {
     Assert-NoUndiscoveredLegacySources -InstallDirs $existingSharedInstallDirs -ActiveSource $source
   }

scripts/pr/release-workflow.test.ts

@@ -532,6 +532,7 @@ describe('release desktop workflow', () => {
     expect(recoveryHelper).toContain('Active CLAUDE_CONFIG_DIR is managed outside Claude Code Haha')
     expect(recoveryHelper).toContain('Test-LexicalPathAtOrBelow')
     expect(recoveryHelper).toContain('-SharedInstallDirs @($PerMachineInstallDir)')
+    expect(recoveryHelper).toContain('$sharedInstallDirInputs.Count -gt 0')
     expect(recoveryHelper).toContain('per-user default-mode reinstall scanned the packaged application tree')
     expect(recoveryHelper).toContain('untrusted-elevated')
     expect(recoveryHelper).toContain('External CLAUDE_CONFIG_DIR is active while install-contained legacy data still exists')