Phase B (T1-5/T1-6/T2-2/T2-8/T2-12): download manager flyout w/ speed+pause/resume/cancel, bookmark bar, tab sleeping, tab search (open+closed), context menu w/ 'download video from this link' (79 tests GREEN)

VideoDownloader.App/Browser/Features/TabSuspendService.cs

@@ -0,0 +1,41 @@
+using VideoDownloader.Browser.Tabs;
+
+namespace VideoDownloader.App.Browser.Features;
+
+/// <summary>
+/// 탭 절전(T2-2, Edge Sleeping Tabs 패턴): 유휴 비활성 탭을 TrySuspendAsync 로
+/// 서스펜드해 메모리를 회수한다. 실제 서스펜드 수행은 주입(suspendAction) —
+/// WebView2 TrySuspendAsync 는 뷰가 숨겨진(비활성) 탭에서만 동작.
+/// </summary>
+public sealed class TabSuspendService
+{
+    private readonly TimeSpan _idleTimeout;
+    private readonly Func<TabItem, bool> _suspendAction;
+    private readonly Func<TabItem, bool> _canSuspend;
+
+    public TabSuspendService(TimeSpan idleTimeout, Func<TabItem, bool> suspendAction, Func<TabItem, bool> canSuspend)
+    {
+        _idleTimeout = idleTimeout;
+        _suspendAction = suspendAction;
+        _canSuspend = canSuspend;
+    }
+
+    /// <summary>유휴 비활성 탭 서스펜드. 반환: 서스펜드된 탭 수.</summary>
+    public int SuspendIdleTabs(IEnumerable<TabItem> tabs, TabItem active, DateTime now)
+    {
+        var count = 0;
+        foreach (var tab in tabs)
+        {
+            if (ReferenceEquals(tab, active)) continue;
+            if (tab.IsSuspended) continue;
+            if (!_canSuspend(tab)) continue;
+            if (now - tab.LastActivated < _idleTimeout) continue;
+            try
+            {
+                if (_suspendAction(tab)) { tab.IsSuspended = true; count++; }
+            }
+            catch { /* 서스펜드 실패는 건너뜀 */ }
+        }
+        return count;
+    }
+}