Use Version.Details.xml as VMR snapshot fallback for manual backflow

When someone runs 'darc vmr backflow' manually and pushes directly,
the commit message doesn't contain the standard 'Backflow from ... / <sha>'
format that the script parses. However, the VMR source SHA is always
updated in eng/Version.Details.xml's <Source> element.

This adds a fallback: when no VMR SHA is found in commit messages,
read Version.Details.xml from the PR branch to get the actual snapshot.
This gives accurate freshness reporting and fix tracing even after
manual backflow operations.

Author: lewing

.github/skills/vmr-codeflow-status/scripts/Get-CodeflowStatus.ps1

@@ -420,19 +420,34 @@ if ($prCommits) {
     }
 }
 
+# Fallback: if no VMR SHA found in commit messages, check eng/Version.Details.xml on the PR branch
+# This catches manual backflow (e.g., `darc vmr backflow` pushed directly) which updates
+# the <Source> element but doesn't use a parseable commit message format
+$versionDetailsVmrCommit = $null
+if (-not $branchVmrCommit -and -not $isForwardFlow) {
+    $vdContent = Invoke-GitHubApi "/repos/$Repository/contents/eng/Version.Details.xml?ref=$($pr.headRefName)" -Raw
+    if ($vdContent -and $vdContent -match '<Source\s+[^>]*Sha="([a-fA-F0-9]+)"') {
+        $versionDetailsVmrCommit = $Matches[1]
+        if (-not $vmrCommit -or -not ($vmrCommit.StartsWith($versionDetailsVmrCommit) -or $versionDetailsVmrCommit.StartsWith($vmrCommit))) {
+            $branchVmrCommit = $versionDetailsVmrCommit
+        }
+    }
+}
+
 if ($branchVmrCommit -or $vmrCommit) {
     Write-Section "Snapshot Validation"
     $usedBranchSnapshot = $false
     if ($branchVmrCommit -and $vmrCommit) {
         $bodyShort = Get-ShortSha $vmrCommit
-        $branchShort = $branchVmrCommit  # already short from commit message
+        $branchShort = Get-ShortSha $branchVmrCommit
+        $snapshotSourceLabel = if ($versionDetailsVmrCommit -and $branchVmrCommit -eq $versionDetailsVmrCommit) { "Version.Details.xml" } else { "branch commit" }
         if ($vmrCommit.StartsWith($branchVmrCommit) -or $branchVmrCommit.StartsWith($vmrCommit)) {
-            Write-Host "  ✅ PR body snapshot ($bodyShort) matches branch commit ($branchShort)" -ForegroundColor Green
+            Write-Host "  ✅ PR body snapshot ($bodyShort) matches $snapshotSourceLabel ($branchShort)" -ForegroundColor Green
         }
         else {
-            Write-Host "  ⚠️  MISMATCH: PR body claims $(Get-ShortSha $vmrCommit) but branch commit references $branchVmrCommit" -ForegroundColor Red
-            Write-Host "  The PR body may be stale — using branch commit ($branchVmrCommit) for freshness check" -ForegroundColor Yellow
-            # Resolve the short SHA from the branch commit to a full SHA for accurate comparison
+            Write-Host "  ⚠️  MISMATCH: PR body claims $bodyShort but $snapshotSourceLabel references $branchShort" -ForegroundColor Red
+            Write-Host "  The PR body may be stale — using $snapshotSourceLabel ($branchShort) for freshness check" -ForegroundColor Yellow
+            # Resolve the SHA to a full SHA for accurate comparison
             $resolvedCommit = Invoke-GitHubApi "/repos/$freshnessRepo/commits/$branchVmrCommit"
             if ($resolvedCommit) {
                 $vmrCommit = $resolvedCommit.sha
@@ -453,19 +468,26 @@ if ($branchVmrCommit -or $vmrCommit) {
         }
     }
     elseif ($vmrCommit -and -not $branchVmrCommit) {
-        $commitCount = if ($prCommits) { $prCommits.Count } else { 0 }
-        if ($commitCount -eq 1) {
-            $firstMsg = $prCommits[0].messageHeadline
-            if ($firstMsg -match "^Initial commit for subscription") {
-                Write-Host "  ℹ️  PR has only an initial subscription commit — PR body snapshot ($(Get-ShortSha $vmrCommit)) not yet verifiable from branch" -ForegroundColor DarkGray
+        # No mismatch from commit messages or Version.Details.xml
+        # Check if Version.Details.xml confirmed the PR body SHA
+        if ($versionDetailsVmrCommit -and ($vmrCommit.StartsWith($versionDetailsVmrCommit) -or $versionDetailsVmrCommit.StartsWith($vmrCommit))) {
+            Write-Host "  ✅ PR body snapshot ($(Get-ShortSha $vmrCommit)) confirmed by Version.Details.xml" -ForegroundColor Green
+        }
+        else {
+            $commitCount = if ($prCommits) { $prCommits.Count } else { 0 }
+            if ($commitCount -eq 1) {
+                $firstMsg = $prCommits[0].messageHeadline
+                if ($firstMsg -match "^Initial commit for subscription") {
+                    Write-Host "  ℹ️  PR has only an initial subscription commit — PR body snapshot ($(Get-ShortSha $vmrCommit)) not yet verifiable from branch" -ForegroundColor DarkGray
+                }
+                else {
+                    Write-Host "  ⚠️  No VMR SHA found in branch commit messages — trusting PR body ($(Get-ShortSha $vmrCommit))" -ForegroundColor Yellow
+                }
             }
             else {
-                Write-Host "  ⚠️  No VMR SHA found in branch commit messages — trusting PR body ($(Get-ShortSha $vmrCommit))" -ForegroundColor Yellow
+                Write-Host "  ⚠️  No VMR SHA found in $commitCount branch commit messages — trusting PR body ($(Get-ShortSha $vmrCommit))" -ForegroundColor Yellow
             }
         }
-        else {
-            Write-Host "  ⚠️  No VMR SHA found in $commitCount branch commit messages — trusting PR body ($(Get-ShortSha $vmrCommit))" -ForegroundColor Yellow
-        }
     }
 }
 
@@ -485,7 +507,10 @@ if ($vmrCommit -and $vmrBranch) {
     if ($branchHead) {
         $sourceHeadSha = $branchHead.sha
         $sourceHeadDate = $branchHead.commit.committer.date
-        $snapshotSource = if ($usedBranchSnapshot) { "from branch commit" } else { "from PR body" }
+        $snapshotSource = if ($usedBranchSnapshot) {
+            if ($versionDetailsVmrCommit -and $vmrCommit.StartsWith($versionDetailsVmrCommit)) { "from Version.Details.xml" }
+            else { "from branch commit" }
+        } else { "from PR body" }
         Write-Status "PR snapshot" "$(Get-ShortSha $vmrCommit) ($snapshotSource)"
         Write-Status "$freshnessRepoLabel HEAD" "$(Get-ShortSha $sourceHeadSha) ($sourceHeadDate)"