diff --git a/scripts/Invoke-CIJob.ps1 b/scripts/Invoke-CIJob.ps1
index 21e7936..73c1e45 100644
--- a/scripts/Invoke-CIJob.ps1
+++ b/scripts/Invoke-CIJob.ps1
@@ -195,11 +195,7 @@ try {
     # into the VM environment.
     Write-Host "`n[Phase 1/6] Cloning repository on host..."
     if (Test-Path $hostCloneDir) { Remove-Item $hostCloneDir -Recurse -Force }
-    # Skip --depth 1 when a specific commit is requested: shallow clones
-    # only contain HEAD, so checkout of an older commit will fail.
-    $gitArgs = @('clone')
-    if ([string]::IsNullOrWhiteSpace($Commit)) { $gitArgs += @('--depth', '1') }
-    $gitArgs += @('--branch', $Branch)
+    $gitArgs = @('clone', '--depth', '1', '--branch', $Branch)
     if ($Submodules) { $gitArgs += '--recurse-submodules' }
     $gitArgs += @($RepoUrl, $hostCloneDir)
     $ErrorActionPreference = 'Continue'
@@ -213,6 +209,14 @@ try {
         $ErrorActionPreference = 'Continue'
         $gitOutput = & git -C $hostCloneDir checkout $Commit 2>&1 | ForEach-Object { "$_" }
         $gitExit = $LASTEXITCODE
+        if ($gitExit -ne 0) {
+            # Commit not in shallow history (e.g. manual run on older SHA).
+            # Fetch full history and retry.
+            Write-Host "[Invoke-CIJob] Shallow checkout failed — fetching full history..."
+            & git -C $hostCloneDir fetch --unshallow 2>&1 | Out-Null
+            $gitOutput = & git -C $hostCloneDir checkout $Commit 2>&1 | ForEach-Object { "$_" }
+            $gitExit = $LASTEXITCODE
+        }
         $ErrorActionPreference = 'Stop'
         if ($gitExit -ne 0) {
             throw "git checkout $Commit failed (exit $gitExit):`n$($gitOutput -join "`n")"