fix: refresh occluded browser windows before plugin capture

plugins/open-computer-use/window-snapshot.ps1

@@ -0,0 +1,44 @@
+# Refresh the target's compositor before reading its accessibility tree and pixels.
+# Chromium can suspend page painting while fully covered. PrintWindow alone can
+# then return an old but otherwise valid bitmap. Do not activate or resize windows.
+function Build-Snapshot([string]$query, $TextLimit = $script:DefaultTextLimit, [int]$MaxTreeNodes = $script:AccessibilityTreeMaxNodeCount, [int]$MaxTreeDepth = $script:AccessibilityTreeMaxDepth) {
+    $process = Resolve-App $query
+    $hwnd = [IntPtr]$process.MainWindowHandle
+    $wasTopmost = ([OCUWin32]::GetWindowLong($hwnd, -20) -band 8) -ne 0
+    $previous = [OCUWin32]::GetWindow($hwnd, 3)
+    $raised = $false
+    try {
+        if ($null -ne (Get-CapturableWindowFrame $hwnd)) {
+            # NOMOVE | NOSIZE | NOACTIVATE | NOOWNERZORDER. This may briefly expose
+            # the authorized target, but never focuses or captures another window.
+            $raised = [OCUWin32]::SetWindowPos($hwnd, [IntPtr](-1), 0, 0, 0, 0, 0x213)
+            if ($raised) {
+                Start-Sleep -Milliseconds 300
+                [void][OCUWin32]::DwmFlush()
+            }
+        }
+        $element = Get-MainElement $process
+        $bounds = Get-WindowBounds $process $element
+        $rendered = Render-Tree $element $bounds $TextLimit $MaxTreeNodes $MaxTreeDepth
+        $image = if ($raised) { Capture-WindowPngBase64 $bounds $hwnd } else { $null }
+        [pscustomobject]@{
+            app = [pscustomobject]@{ name=$process.ProcessName; bundleIdentifier=$process.ProcessName; pid=[int]$process.Id }
+            windowTitle = Limit-Text $process.MainWindowTitle $TextLimit
+            windowBounds = $bounds
+            screenshotPngBase64 = $image
+            treeLines = @($rendered.lines)
+            focusedSummary = Get-FocusedSummary $process.Id $TextLimit
+            selectedText = Get-SelectedText $process.Id $TextLimit
+            elements = @($rendered.records)
+        }
+    } finally {
+        if ($raised) {
+            if (-not $wasTopmost) {
+                [void][OCUWin32]::SetWindowPos($hwnd, [IntPtr](-2), 0, 0, 0, 0, 0x213)
+            }
+            if ($previous -ne [IntPtr]::Zero -and [OCUWin32]::IsWindow($previous)) {
+                [void][OCUWin32]::SetWindowPos($hwnd, $previous, 0, 0, 0, 0, 0x213)
+            }
+        }
+    }
+}