diff --git a/.gitea/workflows/windows-smoke.yml b/.gitea/workflows/windows-smoke.yml
index 084e2bd..1c1ba77 100644
--- a/.gitea/workflows/windows-smoke.yml
+++ b/.gitea/workflows/windows-smoke.yml
@@ -5,7 +5,8 @@
 # (playwright-core over CDP): boots to the login screen, local server address,
 # microphone permission for the app and not for a foreign page, the call page's
 # own origin + isolation, the Credential Manager round trip. Features a build
-# doesn't have are reported "n/a".
+# doesn't have are reported "n/a". Then it updates the app while it is running,
+# the way the auto-updater does (#1).
 #
 # Run it from the Actions tab (workflow_dispatch):
 # - no `ref`: tests the published nightly installer (a couple of minutes);
@@ -121,6 +122,39 @@ jobs:
           try { (Invoke-WebRequest -UseBasicParsing http://localhost:44548/ -TimeoutSec 5).StatusCode | Write-Host } catch { Write-Host "44548: $($_.Exception.Message)" }
           node smoke-deps\windows-smoke.mjs smoke-out
 
+      # cinny-desktop #1: an auto-update over the RUNNING app. tauri-plugin-updater
+      # starts the installer in passive update mode (/P /UPDATE) and the app then
+      # exits; if it was slow to let go of cinny.exe, NSIS stopped on "Error opening
+      # file for writing". The installer's pre-install hook (src-tauri/nsis/
+      # hooks.nsh) now waits for the file to be writable. Here the app stays up 3 s
+      # after the installer starts, then goes. Pass = the installer finishes on its
+      # own (no dialog), exits 0, and has rewritten cinny.exe (its timestamp was set
+      # to 2000 first; NSIS writes the build's own timestamp back).
+      - name: Update over the running app (#1)
+        shell: powershell
+        run: |
+          Get-Process cinny -ErrorAction SilentlyContinue | Stop-Process -Force
+          $app = Join-Path $env:LOCALAPPDATA 'Lotus Chat\cinny.exe'
+          (Get-Item $app).LastWriteTime = Get-Date '2000-01-01'
+          Start-Process $app
+          Start-Sleep -Seconds 10
+          if (-not (Get-Process cinny -ErrorAction SilentlyContinue)) { Write-Error 'app did not start'; exit 1 }
+          $inst = Start-Process smoke-installer\setup.exe -ArgumentList '/P', '/UPDATE' -PassThru
+          Start-Sleep -Seconds 3
+          Get-Process cinny -ErrorAction SilentlyContinue | Stop-Process -Force
+          if (-not $inst.WaitForExit(90000)) {
+            Write-Host '--- windows with a title (an error dialog would be here)'
+            Get-Process | Where-Object { $_.MainWindowTitle } | Select-Object Name, MainWindowTitle | Format-Table | Out-String | Write-Host
+            $inst | Stop-Process -Force
+            Write-Error 'installer did not finish within 90 s (stuck on a dialog?)'
+            exit 1
+          }
+          $written = (Get-Item $app).LastWriteTime
+          Write-Host "installer exit code $($inst.ExitCode); cinny.exe timestamp now $written"
+          if ($inst.ExitCode -ne 0) { Write-Error "installer exit code $($inst.ExitCode)"; exit 1 }
+          if ($written -lt (Get-Date '2001-01-01')) { Write-Error 'cinny.exe was not rewritten'; exit 1 }
+          Get-Process cinny -ErrorAction SilentlyContinue | Stop-Process -Force
+
       - name: Stop the app
         if: ${{ always() }}
         shell: powershell