ci(windows): atomic restore+build to close inter-step deletion window

.gitea/workflows/build-windows.yml

@@ -237,27 +237,53 @@ jobs:
             throw "target\release\librustdesk.dll missing after cargo build"
           }
 
-      - name: Restore flutter/windows if cargo build wiped it
-        shell: bash
-        run: |
-          if [ ! -d flutter/windows ]; then
-            echo "flutter/windows missing after cargo build -- restoring from git"
-            git status --porcelain | grep -E "flutter/windows" | head -10 || true
-            git checkout HEAD -- flutter/windows
-          fi
-          test -d flutter/windows && echo "flutter/windows present: $(find flutter/windows -type f | wc -l) files"
-          test -f flutter/windows/CMakeLists.txt || { echo "CMakeLists.txt missing"; exit 1; }
-
-      - name: Flutter build windows
+      # Restore + build are intentionally one step. flutter/windows has been
+      # observed to disappear between steps on this runner (cause unidentified --
+      # likely Windows Defender quarantine, possibly act_runner workspace handling).
+      # Keeping them atomic eliminates any window of opportunity for that to happen.
+      - name: Flutter build windows (with last-second restore)
         shell: pwsh
         run: |
+          $cmake = '.\flutter\windows\CMakeLists.txt'
+
+          Write-Host "== Pre-flight check =="
+          Write-Host "pwd: $(Get-Location)"
+          if (Test-Path .\flutter\windows) {
+            Write-Host "flutter/windows present: $((Get-ChildItem -Recurse .\flutter\windows -File).Count) files"
+          } else {
+            Write-Host "flutter/windows MISSING"
+          }
+
+          if (-not (Test-Path $cmake)) {
+            Write-Host "`n== Restoring flutter/windows from git index =="
+            git status --porcelain | Where-Object { $_ -match 'flutter/windows' } | Select-Object -First 10
+            git checkout HEAD -- flutter/windows
+            if ($LASTEXITCODE -ne 0) { throw "git checkout HEAD -- flutter/windows failed" }
+            if (-not (Test-Path $cmake)) {
+              Write-Host "git ls-files flutter/windows:"
+              git ls-files flutter/windows | Select-Object -First 5
+              throw "Restore did not produce $cmake"
+            }
+            Write-Host "Restored: $((Get-ChildItem -Recurse .\flutter\windows -File).Count) files"
+          }
+
+          # Touch a marker so we can confirm later (in logs) that this guard ran.
+          $marker = ".\flutter\windows\.restored-at"
+          Set-Content -Path $marker -Value (Get-Date -Format o)
+
+          Write-Host "`n== Running flutter build windows --release =="
           Push-Location flutter
           flutter build windows --release
-          if ($LASTEXITCODE -ne 0) { throw "flutter build windows failed" }
+          $rc = $LASTEXITCODE
           Pop-Location
+          if ($rc -ne 0) {
+            Write-Host "`n!! flutter build failed -- post-mortem state of flutter/windows: !!"
+            if (Test-Path .\flutter\windows) { Get-ChildItem .\flutter\windows -Force }
+            else { Write-Host "(does not exist)" }
+            throw "flutter build windows failed ($rc)"
+          }
 
-          # Mirror what build.py's build_flutter_windows() does after flutter build:
-          # copy the virtual_display dylib next to rustdesk.exe.
+          # Mirror what build.py's build_flutter_windows() does after flutter build.
           Copy-Item -Force `
             target\release\deps\dylib_virtual_display.dll `
             flutter\build\windows\x64\runner\Release\