From 00a822eaebee3a64d4e804de36cade1e517b1c64 Mon Sep 17 00:00:00 2001
From: Yun Chan <yunchan@twentyoz.kr>
Date: Sat, 15 Aug 2026 12:14:35 +0900
Subject: [PATCH] Phase 0 (T1-3/4/7/9/11): find bar w/ native Find API + search
 engine + site zoom + force reload + F11, wired into MainWindow, E2E smoke (39
 tests)

---
 VideoDownloader.App/Browser/FindSession.cs    | 126 ++++++++++++++++
 VideoDownloader.App/MainWindow.xaml           |  46 +++++-
 VideoDownloader.App/MainWindow.xaml.cs        | 139 ++++++++++++++++--
 VideoDownloader.App/SettingsWindow.xaml       |   8 +
 VideoDownloader.App/SettingsWindow.xaml.cs    |  15 ++
 .../VideoDownloader.App.csproj                |   5 +
 VideoDownloader.Core/Config/AppConfig.cs      |   3 +
 .../Browser/FindSessionTests.cs               |  98 ++++++++++++
 .../E2E/MainWindowSmokeE2ETests.cs            |  58 ++++++++
 .../E2E/WebView2FindE2ETests.cs               |  71 +++++++++
 .../Infrastructure/WpfTestApp.cs              |  33 +++++
 11 files changed, 584 insertions(+), 18 deletions(-)
 create mode 100644 VideoDownloader.App/Browser/FindSession.cs
 create mode 100644 VideoDownloader.Tests/Browser/FindSessionTests.cs
 create mode 100644 VideoDownloader.Tests/E2E/MainWindowSmokeE2ETests.cs
 create mode 100644 VideoDownloader.Tests/E2E/WebView2FindE2ETests.cs
 create mode 100644 VideoDownloader.Tests/Infrastructure/WpfTestApp.cs

diff --git a/VideoDownloader.App/Browser/FindSession.cs b/VideoDownloader.App/Browser/FindSession.cs
new file mode 100644
index 0000000..59a31f5
--- /dev/null
+++ b/VideoDownloader.App/Browser/FindSession.cs
@@ -0,0 +1,126 @@
+using Microsoft.Web.WebView2.Core;
+
+namespace VideoDownloader.App.Browser;
+
+/// <summary>네이티브 Find API 의 최소 추상화(단위 테스트용 fake 교체 가능).</summary>
+public interface IFindApi
+{
+    Task StartAsync(string term, bool caseSensitive, bool matchWord, bool highlightAll);
+    void FindNext();
+    void FindPrevious();
+    void Stop();
+    event EventHandler<int>? MatchCountChanged;
+    event EventHandler<int>? ActiveMatchIndexChanged;
+}
+
+/// <summary>WebView2 네이티브 Find(CoreWebView2.Find) 를 IFindApi 로 감싼 어댑터.
+/// 옵션 객체는 public ctor 가 없어 CoreWebView2Environment.CreateFindOptions() 로 생성.</summary>
+public sealed class WebView2FindApi : IFindApi
+{
+    private readonly CoreWebView2 _cv;
+    private readonly CoreWebView2Environment _env;
+
+    public WebView2FindApi(CoreWebView2 cv, CoreWebView2Environment env)
+    {
+        _cv = cv;
+        _env = env;
+    }
+
+    public Task StartAsync(string term, bool caseSensitive, bool matchWord, bool highlightAll)
+    {
+        var o = _env.CreateFindOptions();
+        o.FindTerm = term;
+        o.IsCaseSensitive = caseSensitive;
+        o.ShouldMatchWord = matchWord;
+        o.ShouldHighlightAllMatches = highlightAll;
+        o.SuppressDefaultFindDialog = true; // 자체 WPF 검색 바 사용
+        return _cv.Find.StartAsync(o);
+    }
+
+    public void FindNext() => _cv.Find.FindNext();
+    public void FindPrevious() => _cv.Find.FindPrevious();
+    public void Stop() => _cv.Find.Stop();
+
+    // 이벤트 인자가 object 로 전달되므로 매치 수는 Find 프로퍼티에서 직접 읽는다.
+    public event EventHandler<int>? MatchCountChanged
+    {
+        add => _cv.Find.MatchCountChanged += (s, _) => value?.Invoke(s, _cv.Find.MatchCount);
+        remove { }
+    }
+
+    public event EventHandler<int>? ActiveMatchIndexChanged
+    {
+        add => _cv.Find.ActiveMatchIndexChanged += (s, _) => value?.Invoke(s, _cv.Find.ActiveMatchIndex);
+        remove { }
+    }
+}
+
+/// <summary>
+/// 페이지 내 검색 세션 상태 머신(T1-3). 용어·매치 수·활성 인덱스를 유지하고
+/// UI(검색 바)가 표시할 "3 / 17" 텍스트를 제공한다.
+/// </summary>
+public sealed class FindSession : IDisposable
+{
+    private readonly IFindApi _api;
+
+    public string Term { get; private set; } = string.Empty;
+    public int MatchCount { get; private set; }
+    public int ActiveMatchIndex { get; private set; }
+    public bool IsCaseSensitive { get; private set; }
+    public bool MatchWholeWord { get; private set; }
+
+    public event Action? StateChanged;
+
+    public FindSession(IFindApi api)
+    {
+        _api = api;
+        _api.MatchCountChanged += (_, n) => { MatchCount = n; StateChanged?.Invoke(); };
+        _api.ActiveMatchIndexChanged += (_, n) => { ActiveMatchIndex = n; StateChanged?.Invoke(); };
+    }
+
+    public string StatusText
+    {
+        get
+        {
+            if (MatchCount <= 0) return "결과 없음";
+            var oneBased = ActiveMatchIndex >= 0 ? ActiveMatchIndex + 1 : 0;
+            return $"{oneBased} / {MatchCount}";
+        }
+    }
+
+    public async Task StartAsync(string term)
+    {
+        Term = term ?? "";
+        if (string.IsNullOrWhiteSpace(term))
+        {
+            Close();
+            return;
+        }
+        MatchCount = 0;
+        ActiveMatchIndex = -1;
+        await _api.StartAsync(Term, IsCaseSensitive, MatchWholeWord, highlightAll: true);
+        StateChanged?.Invoke();
+    }
+
+    public void SetOptions(bool caseSensitive, bool matchWholeWord)
+    {
+        IsCaseSensitive = caseSensitive;
+        MatchWholeWord = matchWholeWord;
+        if (!string.IsNullOrWhiteSpace(Term))
+            _ = StartAsync(Term); // 옵션 변경은 재시작 필요(네이티브 제약)
+    }
+
+    public void Next() => _api.FindNext();
+    public void Previous() => _api.FindPrevious();
+
+    public void Close()
+    {
+        _api.Stop();
+        Term = string.Empty;
+        MatchCount = 0;
+        ActiveMatchIndex = -1;
+        StateChanged?.Invoke();
+    }
+
+    public void Dispose() => Close();
+}
diff --git a/VideoDownloader.App/MainWindow.xaml b/VideoDownloader.App/MainWindow.xaml
index f0cdeb9..eaafcb5 100644
--- a/VideoDownloader.App/MainWindow.xaml
+++ b/VideoDownloader.App/MainWindow.xaml
@@ -159,7 +159,7 @@
         </Grid.RowDefinitions>
 
         <!-- ===== 상단 툴바 (슬림, 전체가 드래그 핸들) ===== -->
-        <Border Grid.Row="0" Background="{StaticResource PanelBg}"
+        <Border x:Name="ToolbarRow" Grid.Row="0" Background="{StaticResource PanelBg}"
                 BorderBrush="{StaticResource AccentFadeBrush}" BorderThickness="0,0,0,2" Padding="20,9,0,9"
                 PreviewMouseLeftButtonDown="TitleBar_PreviewMouseLeftButtonDown">
             <DockPanel>
@@ -217,9 +217,45 @@
                 <ColumnDefinition x:Name="RightCol" Width="420" MinWidth="56" MaxWidth="900"/>
             </Grid.ColumnDefinitions>
 
-            <Border Grid.Column="0" ClipToBounds="True" Background="Black">
-                <wv2:WebView2 Name="Browser"/>
-            </Border>
+            <Grid Grid.Column="0">
+                <Grid.RowDefinitions>
+                    <RowDefinition Height="*"/>
+                    <RowDefinition Height="Auto"/>
+                </Grid.RowDefinitions>
+
+                <Border Grid.Row="0" ClipToBounds="True" Background="Black">
+                    <wv2:WebView2 Name="Browser"/>
+                </Border>
+
+                <!-- 페이지 내 검색 바 (T1-3): WebView2(airspace) 아래에 도킹 -->
+                <Border x:Name="FindBar" Grid.Row="1" Visibility="Collapsed"
+                        Background="{StaticResource PanelBg}" BorderBrush="{StaticResource BorderSubtle}"
+                        BorderThickness="0,1,0,0" Padding="12,6">
+                    <StackPanel Orientation="Horizontal" HorizontalAlignment="Right">
+                        <CheckBox x:Name="FindCaseBox" Style="{StaticResource DarkCheckBox}" Content="Aa"
+                                  ToolTip="대소문자 구분" Margin="0,0,8,0" VerticalAlignment="Center"
+                                  Checked="FindOption_Changed" Unchecked="FindOption_Changed"/>
+                        <CheckBox x:Name="FindWordBox" Style="{StaticResource DarkCheckBox}" Content="단어"
+                                  ToolTip="전체 단어 일치" Margin="0,0,10,0" VerticalAlignment="Center"
+                                  Checked="FindOption_Changed" Unchecked="FindOption_Changed"/>
+                        <Border Background="{StaticResource GlassBg}" BorderBrush="{StaticResource BorderBrush}"
+                                BorderThickness="1" CornerRadius="7" Width="230">
+                            <TextBox x:Name="FindBox" Style="{StaticResource DarkTextBox}" BorderThickness="0"
+                                     Background="Transparent" Padding="10,4" FontSize="12.5"
+                                     VerticalContentAlignment="Center"
+                                     TextChanged="FindBox_TextChanged" PreviewKeyDown="FindBox_PreviewKeyDown"/>
+                        </Border>
+                        <Button Style="{StaticResource IconButton}" Content="&#xE74A;" ToolTip="이전 매치 (Shift+F3)"
+                                Margin="6,0,0,0" Click="FindPrev_Click"/>
+                        <Button Style="{StaticResource IconButton}" Content="&#xE74B;" ToolTip="다음 매치 (F3)"
+                                Margin="2,0,0,0" Click="FindNext_Click"/>
+                        <TextBlock x:Name="FindStatus" Text="" Foreground="{StaticResource TextMuted}" FontSize="11.5"
+                                   VerticalAlignment="Center" Margin="10,0,4,0" MinWidth="52"/>
+                        <Button Style="{StaticResource IconButton}" Content="&#xE711;" ToolTip="닫기 (Esc)"
+                                Click="FindClose_Click"/>
+                    </StackPanel>
+                </Border>
+            </Grid>
 
             <!-- 리사이즈 핸들 (펼침 상태에서만 노출). 드래그로 우측 패널 폭 변경. -->
             <GridSplitter x:Name="RightSplitter" Grid.Column="1" Width="7"
@@ -284,7 +320,7 @@
         </Grid>
 
         <!-- ===== 상태 표시줄 ===== -->
-        <Border Grid.Row="2" Background="{StaticResource PanelBg}"
+        <Border x:Name="StatusBar" Grid.Row="2" Background="{StaticResource PanelBg}"
                 BorderBrush="{StaticResource BorderSubtle}" BorderThickness="0,1,0,0" Padding="16,5">
             <TextBlock Name="StatusText" Foreground="{StaticResource TextMuted}" FontSize="11"
                        TextTrimming="CharacterEllipsis" Text="준비"/>
diff --git a/VideoDownloader.App/MainWindow.xaml.cs b/VideoDownloader.App/MainWindow.xaml.cs
index 4327f3b..14daff4 100644
--- a/VideoDownloader.App/MainWindow.xaml.cs
+++ b/VideoDownloader.App/MainWindow.xaml.cs
@@ -31,6 +31,13 @@ public partial class MainWindow : Window
     private string? _pendingSocialUrl; // 타이틀 확정 시 소셜 카드 제목 갱신용
     private bool _suggesting; // 주소창 인라인 자동완성 도중 (TextChanged 재귀 방지)
 
+    // T1-4 검색엔진 / T1-7 사이트별 줌 / T1-3 페이지 내 검색 / T1-11 전체화면
+    private SearchEngineResolver _resolver = null!;
+    private SiteZoomStore _zoomStore = null!;
+    private FindSession? _findSession;
+    private bool _fullscreen;
+    private WindowState _stateBeforeFullscreen = WindowState.Normal;
+
     // #15 위장 미디어(image/png 등) magic byte 검증용. 세션당 상한 두어 폭주 방지.
     private static readonly HttpClient ProbeClient = new(new HttpClientHandler { AllowAutoRedirect = true })
     { Timeout = TimeSpan.FromSeconds(15) };
@@ -59,6 +66,9 @@ public partial class MainWindow : Window
         BookmarksList.ItemsSource = _bookmarks;
         HistoryList.ItemsSource = _history;
 
+        _resolver = new SearchEngineResolver(_config.SearchEngine);
+        _zoomStore = new SiteZoomStore(Path.Combine(AppDataDir, "sitezoom.json"));
+
         Loaded += async (_, _) => await InitializeBrowserAsync();
         PreviewKeyDown += OnPreviewKeyDown;
         StateChanged += OnWindowStateChanged;
@@ -127,16 +137,19 @@ public partial class MainWindow : Window
     private static extern int DwmSetWindowAttribute(IntPtr hwnd, int attribute, ref int pvAttribute, int cbAttribute);
 
     /// <summary>WebView2 영속 프로필 경로. 쿠키·세션·localStorage·캐시가 여기 보존되어 앱/빌드 재시작에도 유지.</summary>
-    internal static string ProfileFolder => Path.Combine(
-        Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData), "VideoDownloader", "webview");
+    internal static string AppDataDir => Path.Combine(
+        Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData), "VideoDownloader");
+
+    internal static string ProfileFolder => Path.Combine(AppDataDir, "webview");
 
     private async Task InitializeBrowserAsync()
     {
+        CoreWebView2Environment? env = null;
         try
         {
             // 명시적 영속 프로필: 기본(exe 디렉터리) 폴더는 빌드/재배포 시 날아가 로그인이 풀림 → %AppData% 로 고정.
             Directory.CreateDirectory(ProfileFolder);
-            var env = await CoreWebView2Environment.CreateAsync(browserExecutableFolder: null, userDataFolder: ProfileFolder);
+            env = await CoreWebView2Environment.CreateAsync(browserExecutableFolder: null, userDataFolder: ProfileFolder);
             var options = env.CreateCoreWebView2ControllerOptions();
             if (_config.PrivateMode) options.IsInPrivateModeEnabled = true; // InPrivate: 디스크에 아무것도 저장 안 함
             await Browser.EnsureCoreWebView2Async(env, options);
@@ -146,6 +159,20 @@ public partial class MainWindow : Window
         var cv = Browser.CoreWebView2;
         UpdatePrivateButton();
         cv.Settings.AreDevToolsEnabled = true;
+
+        // T1-3 네이티브 Find API 세션 (자체 검색 바)
+        _findSession = new FindSession(new WebView2FindApi(cv, env!));
+        _findSession.StateChanged += () => Dispatcher.BeginInvoke(new Action(() =>
+        {
+            if (_findSession != null) FindStatus.Text = _findSession.StatusText;
+        }));
+
+        // T1-7 사이트별 줌: 네비 완료 시 저장된 배율 적용 (WebView2 는 사이트별 영속 미보장)
+        cv.NavigationCompleted += (_, _) => Dispatcher.BeginInvoke(new Action(() =>
+        {
+            try { Browser.ZoomFactor = _zoomStore.Get(cv.Source); } catch { }
+        }));
+
         cv.WebResourceResponseReceived += OnResponseReceived;
         // #4 팝업/새창을 현재 WebView2 로 강제 라우팅
         cv.NewWindowRequested += (_, ne) =>
@@ -433,12 +460,12 @@ public partial class MainWindow : Window
     private void NavRefresh_Click(object sender, RoutedEventArgs e) => Browser.CoreWebView2?.Reload();
     private void NavHome_Click(object sender, RoutedEventArgs e) => NavigateTo(_config.HomeUrl);
 
-    private void NavigateTo(string? url)
+    internal void NavigateTo(string? url)
     {
-        url = url?.Trim();
-        if (string.IsNullOrEmpty(url)) return;
-        if (!url.StartsWith("http", StringComparison.OrdinalIgnoreCase)) url = "https://" + url;
-        Browser.CoreWebView2?.Navigate(url);
+        // T1-4: URL/검색어 판별 + 기본 엔진·키워드 전환(g, yt, ...)은 리졸버가 담당
+        var intent = _resolver.Resolve(url);
+        if (intent == null) return;
+        Browser.CoreWebView2?.Navigate(intent.Target);
     }
 
     // 소셜 영상 페이지(YouTube/Instagram/X/...) 감지 → yt-dlp 카드 등록.
@@ -486,24 +513,109 @@ public partial class MainWindow : Window
         else Log("지원하는 소셜 영상 링크가 아닙니다 (YouTube·Instagram·X·TikTok·Facebook)");
     }
 
-    // #7 전역 키보드 단축키
+    // #7 전역 키보드 단축키 (+T1-3/T1-9/T1-11)
     private void OnPreviewKeyDown(object sender, KeyEventArgs e)
     {
         var cv = Browser.CoreWebView2;
         var mods = Keyboard.Modifiers;
-        if (mods == ModifierKeys.Control && e.Key == Key.L) { AddressBox.Focus(); AddressBox.SelectAll(); e.Handled = true; }
+
+        // T1-3 검색 바가 열려 있으면 Esc 는 닫기가 우선
+        if (e.Key == Key.Escape && FindBar.Visibility == Visibility.Visible) { CloseFind(); e.Handled = true; }
+        else if (mods == ModifierKeys.Control && e.Key == Key.F) { OpenFind(); e.Handled = true; }
+        else if (e.Key == Key.F3)
+        {
+            if (FindBar.Visibility == Visibility.Visible)
+            {
+                if (mods == ModifierKeys.Shift) _findSession?.Previous(); else _findSession?.Next();
+            }
+            else OpenFind();
+            e.Handled = true;
+        }
+        else if (e.Key == Key.F11) { ToggleFullscreen(); e.Handled = true; }
+        else if (mods == (ModifierKeys.Control | ModifierKeys.Shift) && e.Key == Key.R) { ForceReload(); e.Handled = true; }
+        else if (mods == ModifierKeys.Control && e.Key == Key.L) { AddressBox.Focus(); AddressBox.SelectAll(); e.Handled = true; }
         else if (e.Key == Key.F5 || (mods == ModifierKeys.Control && e.Key == Key.R)) { cv?.Reload(); e.Handled = true; }
         else if (e.Key == Key.Escape) { try { cv?.Stop(); } catch { } e.Handled = true; }
         else if (mods == ModifierKeys.Alt && e.Key == Key.Left) { try { if (cv?.CanGoBack == true) cv.GoBack(); } catch { } e.Handled = true; }
         else if (mods == ModifierKeys.Alt && e.Key == Key.Right) { try { if (cv?.CanGoForward == true) cv.GoForward(); } catch { } e.Handled = true; }
         else if (mods == ModifierKeys.Control)
         {
-            if (e.Key == Key.OemPlus || e.Key == Key.Add) { try { Browser.ZoomFactor = Math.Min(Browser.ZoomFactor + 0.1, 5); } catch { } e.Handled = true; }
-            else if (e.Key == Key.OemMinus || e.Key == Key.Subtract) { try { Browser.ZoomFactor = Math.Max(Browser.ZoomFactor - 0.1, 0.1); } catch { } e.Handled = true; }
-            else if (e.Key == Key.D0) { try { Browser.ZoomFactor = 1.0; } catch { } e.Handled = true; }
+            if (e.Key == Key.OemPlus || e.Key == Key.Add) { try { Browser.ZoomFactor = Math.Min(Browser.ZoomFactor + 0.1, 5); PersistZoom(); } catch { } e.Handled = true; }
+            else if (e.Key == Key.OemMinus || e.Key == Key.Subtract) { try { Browser.ZoomFactor = Math.Max(Browser.ZoomFactor - 0.1, 0.1); PersistZoom(); } catch { } e.Handled = true; }
+            else if (e.Key == Key.D0) { try { Browser.ZoomFactor = 1.0; PersistZoom(); } catch { } e.Handled = true; }
         }
     }
 
+    // ---- T1-3 페이지 내 검색 바 ----
+    internal void OpenFind()
+    {
+        FindBar.Visibility = Visibility.Visible;
+        FindStatus.Text = "";
+        FindBox.Focus();
+        FindBox.SelectAll();
+        if (FindBox.Text.Length > 0) _ = _findSession?.StartAsync(FindBox.Text);
+    }
+
+    internal void CloseFind()
+    {
+        FindBar.Visibility = Visibility.Collapsed;
+        _findSession?.Close();
+        FindStatus.Text = "";
+    }
+
+    private void FindBox_TextChanged(object sender, TextChangedEventArgs e)
+    {
+        if (FindBar.Visibility == Visibility.Visible)
+            _ = _findSession?.StartAsync(FindBox.Text);
+    }
+
+    private void FindBox_PreviewKeyDown(object sender, KeyEventArgs e)
+    {
+        if (e.Key == Key.Enter) { if (Keyboard.Modifiers == ModifierKeys.Shift) _findSession?.Previous(); else _findSession?.Next(); e.Handled = true; }
+        else if (e.Key == Key.Escape) { CloseFind(); e.Handled = true; }
+    }
+
+    private void FindNext_Click(object sender, RoutedEventArgs e) => _findSession?.Next();
+    private void FindPrev_Click(object sender, RoutedEventArgs e) => _findSession?.Previous();
+    private void FindClose_Click(object sender, RoutedEventArgs e) => CloseFind();
+
+    private void FindOption_Changed(object sender, RoutedEventArgs e)
+        => _findSession?.SetOptions(FindCaseBox.IsChecked == true, FindWordBox.IsChecked == true);
+
+    // T1-7 줌 변경을 사이트별 저장소에 영속
+    private void PersistZoom()
+    {
+        var cv = Browser.CoreWebView2;
+        if (cv != null) _zoomStore.Set(cv.Source, Browser.ZoomFactor);
+    }
+
+    // T1-9 강제 새로고침: 디스크 캐시 비우고 다시 로드
+    private async void ForceReload()
+    {
+        var cv = Browser.CoreWebView2;
+        if (cv == null) return;
+        try { await cv.Profile.ClearBrowsingDataAsync(CoreWebView2BrowsingDataKinds.DiskCache); }
+        catch { }
+        try { cv.Reload(); } catch { }
+    }
+
+    // T1-11 전체화면(F11): 툴바/상태바 숨기고 최대화. 재누르면 복원.
+    internal void ToggleFullscreen()
+    {
+        _fullscreen = !_fullscreen;
+        if (_fullscreen)
+        {
+            _stateBeforeFullscreen = WindowState;
+            WindowState = WindowState.Maximized;
+        }
+        else
+        {
+            WindowState = _stateBeforeFullscreen;
+        }
+        ToolbarRow.Visibility = _fullscreen ? Visibility.Collapsed : Visibility.Visible;
+        StatusBar.Visibility = _fullscreen ? Visibility.Collapsed : Visibility.Visible;
+    }
+
     private static string MakeUniqueDownloadName(string folder, string file)
     {
         var p = Path.Combine(folder, file);
@@ -746,6 +858,7 @@ public partial class MainWindow : Window
         {
             _config = w.Config;
             ConfigStore.Save(_config);
+            _resolver = new SearchEngineResolver(_config.SearchEngine); // T1-4 즉시 반영
             _manager.UpdateMaxConcurrent(_config.MaxConcurrentDownloads); // #19 런타임 반영
             if (w.ThemeChanged) RestartApp();
         }
diff --git a/VideoDownloader.App/SettingsWindow.xaml b/VideoDownloader.App/SettingsWindow.xaml
index 278f759..f8d7b6d 100644
--- a/VideoDownloader.App/SettingsWindow.xaml
+++ b/VideoDownloader.App/SettingsWindow.xaml
@@ -55,6 +55,14 @@
                     <TextBox Name="HomeBox" Style="{StaticResource DarkTextBox}" BorderThickness="0" Background="Transparent"/>
                 </Border>
 
+                <StackPanel Margin="0,0,0,18">
+                    <TextBlock Text="기본 검색 엔진 (주소창에 검색어 입력 시)" Foreground="{StaticResource TextPrimary}" FontWeight="SemiBold"/>
+                    <ComboBox Name="SearchEngineBox" Style="{StaticResource DarkComboBox}" Margin="0,6,0,4"
+                              SelectionChanged="SearchEngineBox_SelectionChanged"/>
+                    <TextBlock x:Name="SearchEngineHint" FontSize="11" Foreground="{StaticResource TextMuted}" TextWrapping="Wrap"
+                               Text="주소창에 `g 검색어`, `yt 검색어` 등 키워드를 입력하면 검색 엔진을 즉시 전환할 수 있어요"/>
+                </StackPanel>
+
                 <Grid Margin="0,0,0,18">
                     <Grid.ColumnDefinitions>
                         <ColumnDefinition Width="*"/>
diff --git a/VideoDownloader.App/SettingsWindow.xaml.cs b/VideoDownloader.App/SettingsWindow.xaml.cs
index 6679519..34525e2 100644
--- a/VideoDownloader.App/SettingsWindow.xaml.cs
+++ b/VideoDownloader.App/SettingsWindow.xaml.cs
@@ -4,6 +4,7 @@ using System.Windows.Controls;
 using System.Windows.Input;
 using System.Windows.Interop;
 using Microsoft.Win32;
+using VideoDownloader.App.Browser;
 using VideoDownloader.Core.Config;
 using VideoDownloader.Core.Social;
 
@@ -54,6 +55,19 @@ public partial class SettingsWindow : Window
         ProfileModeText.Text = config.PrivateMode
             ? "개인정보 보호 모드(InPrivate) — 데이터를 저장하지 않습니다"
             : "일반 모드 — 쿠키·세션·localStorage 를 프로필에 보존합니다";
+
+        SearchEngineBox.ItemsSource = SearchEngines.Presets.Select(e => e.Name).ToList();
+        SearchEngineBox.SelectedItem = SearchEngines.FindByName(config.SearchEngine)?.Name ?? "Google";
+        if (SearchEngineBox.SelectedIndex < 0) SearchEngineBox.SelectedIndex = 0;
+    }
+
+    private void SearchEngineBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
+    {
+        if (SearchEngineHint == null) return;
+        var engine = SearchEngines.FindByName(SearchEngineBox.SelectedItem as string);
+        SearchEngineHint.Text = engine == null
+            ? "주소창에 검색어를 입력하면 검색합니다"
+            : $"주소창에 검색어 입력 시 {engine.Name}(으)로 검색합니다. `g 검색어`처럼 키워드로 즉시 전환도 가능해요";
     }
 
     private void BrowseFolder(object sender, RoutedEventArgs e)
@@ -134,6 +148,7 @@ public partial class SettingsWindow : Window
         Config.AutoInstallDeno = AutoInstallDenoBox.IsChecked == true;
         Config.DefaultSocialQuality = (DefaultQualityBox.SelectedValue as string) ?? "best";
         Config.YoutubePlayerClients = string.IsNullOrWhiteSpace(YoutubeClientsBox.Text) ? null : YoutubeClientsBox.Text.Trim();
+        Config.SearchEngine = SearchEngineBox.SelectedItem as string ?? "Google";
 
         DialogResult = true;
     }
diff --git a/VideoDownloader.App/VideoDownloader.App.csproj b/VideoDownloader.App/VideoDownloader.App.csproj
index 1dcb487..358ac62 100644
--- a/VideoDownloader.App/VideoDownloader.App.csproj
+++ b/VideoDownloader.App/VideoDownloader.App.csproj
@@ -33,4 +33,9 @@
     <PackageReference Include="Microsoft.Web.WebView2" Version="1.0.4078.44" />
   </ItemGroup>
 
+  <!-- E2E 테스트(InternalsVisibleTo) -->
+  <ItemGroup>
+    <InternalsVisibleTo Include="VideoDownloader.Tests" />
+  </ItemGroup>
+
 </Project>
diff --git a/VideoDownloader.Core/Config/AppConfig.cs b/VideoDownloader.Core/Config/AppConfig.cs
index e1d3759..5fcc707 100644
--- a/VideoDownloader.Core/Config/AppConfig.cs
+++ b/VideoDownloader.Core/Config/AppConfig.cs
@@ -67,4 +67,7 @@ public class AppConfig
 
     /// <summary>개인정보 보호(InPrivate) 모드: 쿠키·세션·localStorage 를 디스크에 저장하지 않는다. 적용 시 앱 재시작.</summary>
     public bool PrivateMode { get; set; } = false;
+
+    /// <summary>주소창 기본 검색 엔진(SearchEngines.Presets 의 Name). 검색어 입력 시 이 엔진으로 검색.</summary>
+    public string SearchEngine { get; set; } = "Google";
 }
diff --git a/VideoDownloader.Tests/Browser/FindSessionTests.cs b/VideoDownloader.Tests/Browser/FindSessionTests.cs
new file mode 100644
index 0000000..5d3c27b
--- /dev/null
+++ b/VideoDownloader.Tests/Browser/FindSessionTests.cs
@@ -0,0 +1,98 @@
+using VideoDownloader.App.Browser;
+
+namespace VideoDownloader.Tests.Browser;
+
+// T1-3 페이지 내 검색: FindSession 은 네이티브 Find API(IFindApi) 위의 상태 머신.
+public class FindSessionTests
+{
+    private sealed class FakeFindApi : IFindApi
+    {
+        public string? LastTerm;
+        public int StartCount, NextCount, PrevCount, StopCount;
+        public int MatchCount { get; set; }
+        public int ActiveIndex { get; set; }
+
+        public event EventHandler<int>? MatchCountChanged;
+        public event EventHandler<int>? ActiveMatchIndexChanged;
+
+        public Task StartAsync(string term, bool caseSensitive, bool matchWord, bool highlightAll)
+        {
+            StartCount++; LastTerm = term; return Task.CompletedTask;
+        }
+        public void FindNext() => NextCount++;
+        public void FindPrevious() => PrevCount++;
+        public void Stop() => StopCount++;
+
+        public void RaiseCount(int n) { MatchCount = n; MatchCountChanged?.Invoke(this, n); }
+        public void RaiseActive(int n) { ActiveIndex = n; ActiveMatchIndexChanged?.Invoke(this, n); }
+    }
+
+    [Fact]
+    public void Start는_API로_용어를_전달하고_카운트_이벤트를_구독_반영한다()
+    {
+        var api = new FakeFindApi();
+        var session = new FindSession(api);
+
+        session.StartAsync("hello").Wait();
+        api.RaiseCount(7);
+
+        Assert.Equal(1, api.StartCount);
+        Assert.Equal("hello", api.LastTerm);
+        Assert.Equal(7, session.MatchCount);
+    }
+
+    [Fact]
+    public void Next_Previous는_API에_위임한다()
+    {
+        var api = new FakeFindApi();
+        var session = new FindSession(api);
+        session.StartAsync("x").Wait();
+
+        session.Next();
+        session.Previous();
+
+        Assert.Equal(1, api.NextCount);
+        Assert.Equal(1, api.PrevCount);
+    }
+
+    [Fact]
+    public void ActiveMatchIndex_이벤트가_상태에_반영된다()
+    {
+        var api = new FakeFindApi();
+        var session = new FindSession(api);
+        session.StartAsync("x").Wait();
+
+        api.RaiseActive(3);
+        Assert.Equal(3, session.ActiveMatchIndex);
+    }
+
+    [Fact]
+    public void 빈_용어로_Start하면_Stop만_호출된다()
+    {
+        var api = new FakeFindApi();
+        var session = new FindSession(api);
+
+        session.StartAsync("   ").Wait();
+
+        Assert.Equal(0, api.StartCount);
+        Assert.Equal(1, api.StopCount);
+        Assert.Equal(0, session.MatchCount);
+    }
+
+    [Fact]
+    public void Close는_Stop을_호출하고_상태를_초기화한다()
+    {
+        var api = new FakeFindApi();
+        var session = new FindSession(api);
+        session.StartAsync("x").Wait();
+        api.RaiseCount(5);
+        api.RaiseActive(2);
+
+        session.Close();
+
+        Assert.Equal(1, api.StopCount);
+        Assert.Equal(0, session.MatchCount);
+        Assert.Equal(-1, session.ActiveMatchIndex); // -1 = 활성 매치 없음(Start 초기값과 동일 센티넬)
+        Assert.Equal(string.Empty, session.Term);
+    }
+}
diff --git a/VideoDownloader.Tests/E2E/MainWindowSmokeE2ETests.cs b/VideoDownloader.Tests/E2E/MainWindowSmokeE2ETests.cs
new file mode 100644
index 0000000..aae07ce
--- /dev/null
+++ b/VideoDownloader.Tests/E2E/MainWindowSmokeE2ETests.cs
@@ -0,0 +1,58 @@
+using System.Windows;
+using VideoDownloader.App;
+using VideoDownloader.Tests.Infrastructure;
+
+namespace VideoDownloader.Tests.E2E;
+
+/// <summary>
+/// E2E 스모크: 실제 MainWindow 를 기동해 WebView2 초기화·탐색·검색 바·전체화면 전환이
+/// 크래시 없이 동작하는지 검증한다(Phase 0 통합 확인). 네트워크 의존 제거를 위해 about:blank 사용.
+/// </summary>
+[Collection("E2E")]
+public class MainWindowSmokeE2ETests
+{
+    [Fact]
+    public async Task MainWindow_기동_탐색_검색바_전체화면_스모크()
+    {
+        using var sta = StaDispatcher.Start();
+        WpfTestApp.Ensure(sta.Dispatcher);
+        var ok = await sta.InvokeAsync(async () =>
+        {
+            var window = new MainWindow();
+            window.Show();
+
+            // WebView2 초기화 대기 (Loaded → InitializeBrowserAsync)
+            var cv = await Wait.Until(
+                () => Task.FromResult(window.Browser.CoreWebView2),
+                c => c != null, 30000);
+
+            // about:blank 탐색 (네트워크 불필요)
+            window.NavigateTo("about:blank");
+            await Wait.Until(
+                () => Task.FromResult(cv.Source ?? ""),
+                s => s.Contains("about:blank"), 15000);
+
+            // T1-3 검색 바 열기/닫기
+            window.OpenFind();
+            var findVisible = window.FindBar.Visibility == Visibility.Visible;
+            window.CloseFind();
+            var findCollapsed = window.FindBar.Visibility == Visibility.Collapsed;
+
+            // T1-11 전체화면 토글
+            window.ToggleFullscreen();
+            var toolbarHidden = window.ToolbarRow.Visibility == Visibility.Collapsed;
+            window.ToggleFullscreen();
+            var toolbarBack = window.ToolbarRow.Visibility == Visibility.Visible;
+
+            window.Close();
+            return (init: cv != null, nav: true, findVisible, findCollapsed, toolbarHidden, toolbarBack);
+        });
+
+        Assert.True(ok.init, "WebView2 초기화 실패");
+        Assert.True(ok.nav);
+        Assert.True(ok.findVisible, "검색 바 미표시");
+        Assert.True(ok.findCollapsed, "검색 바 미닫힘");
+        Assert.True(ok.toolbarHidden, "전체화면에서 툴바 미숨김");
+        Assert.True(ok.toolbarBack, "전체화면 복원 실패");
+    }
+}
diff --git a/VideoDownloader.Tests/E2E/WebView2FindE2ETests.cs b/VideoDownloader.Tests/E2E/WebView2FindE2ETests.cs
new file mode 100644
index 0000000..ff2a95d
--- /dev/null
+++ b/VideoDownloader.Tests/E2E/WebView2FindE2ETests.cs
@@ -0,0 +1,71 @@
+using System.Windows;
+using System.Windows.Threading;
+using Microsoft.Web.WebView2.Core;
+using VideoDownloader.Tests.Infrastructure;
+
+namespace VideoDownloader.Tests.E2E;
+
+/// <summary>
+/// E2E: 실제 WebView2 + 네이티브 Find API(CoreWebView2.Find) 검증(T1-3).
+/// WebView2 런타임 위에서 매치 카운트/활성 인덱스가 실제로 발생하는지 확인한다.
+/// </summary>
+[Collection("E2E")]
+public class WebView2FindE2ETests
+{
+    [Fact]
+    public async Task 네이티브_Find로_매치_수와_활성_인덱스를_얻는다()
+    {
+        using var sta = StaDispatcher.Start();
+        var udf = Path.Combine(Path.GetTempPath(), $"vd_e2e_{Guid.NewGuid():N}");
+        var result = await sta.InvokeAsync(async () =>
+        {
+            var window = new Window();
+            var browser = new Microsoft.Web.WebView2.Wpf.WebView2();
+            window.Content = browser;
+            window.Show();
+
+            var env = await CoreWebView2Environment.CreateAsync(userDataFolder: udf);
+            await browser.EnsureCoreWebView2Async(env);
+            var cv = browser.CoreWebView2;
+            cv.Settings.AreDefaultScriptDialogsEnabled = false;
+
+            var html = "<html><body><p>hello world hello brave hello</p></body></html>";
+            cv.NavigateToString(html);
+            await WaitUntilNavCompleted(cv);
+
+            // 네이티브 Find API — SuppressDefaultFindDialog 로 자체 UI 전제 검증
+            int matchCount = -1, activeIndex = -1;
+            cv.Find.MatchCountChanged += (_, _) => matchCount = cv.Find.MatchCount;
+            cv.Find.ActiveMatchIndexChanged += (_, _) => activeIndex = cv.Find.ActiveMatchIndex;
+
+            var options = env.CreateFindOptions();
+            options.FindTerm = "hello";
+            options.ShouldHighlightAllMatches = true;
+            options.SuppressDefaultFindDialog = true;
+            await cv.Find.StartAsync(options);
+
+            await Wait.Until(() => Task.FromResult(matchCount), c => c > 0, 10000);
+            var countAfterStart = matchCount;
+
+            cv.Find.FindNext();
+            await Wait.Until(() => Task.FromResult(activeIndex), i => i >= 1, 10000);
+
+            cv.Find.Stop();
+            window.Close();
+            return (countAfterStart, activeIndex);
+        });
+
+        try { Directory.Delete(udf, true); } catch { }
+        Assert.Equal(3, result.countAfterStart);
+        Assert.True(result.activeIndex >= 1, $"활성 인덱스가 진행되지 않음: {result.activeIndex}");
+    }
+
+    private static Task WaitUntilNavCompleted(CoreWebView2 cv)
+    {
+        var tcs = new TaskCompletionSource(TaskCreationOptions.RunContinuationsAsynchronously);
+        EventHandler<CoreWebView2NavigationCompletedEventArgs>? h = null;
+        h = (_, _) => { cv.NavigationCompleted -= h; tcs.TrySetResult(); };
+        cv.NavigationCompleted += h;
+        return tcs.Task.WaitAsync(TimeSpan.FromSeconds(15));
+    }
+}
diff --git a/VideoDownloader.Tests/Infrastructure/WpfTestApp.cs b/VideoDownloader.Tests/Infrastructure/WpfTestApp.cs
new file mode 100644
index 0000000..736a779
--- /dev/null
+++ b/VideoDownloader.Tests/Infrastructure/WpfTestApp.cs
@@ -0,0 +1,33 @@
+using System.Windows;
+using VideoDownloader.App;
+
+namespace VideoDownloader.Tests.Infrastructure;
+
+/// <summary>
+/// 테스트 프로세스에는 App.xaml 의 리소스가 없으므로, App 어셈블리의 테마 사전을
+/// 테스트 전용 Application 에 로드한다(앱의 App.ApplyTheme 과 동일 순서: 색 → 스타일).
+/// </summary>
+public static class WpfTestApp
+{
+    private static bool _initialized;
+
+    public static void Ensure(System.Windows.Threading.Dispatcher dispatcher)
+    {
+        dispatcher.Invoke(() =>
+        {
+            if (_initialized) return;
+            if (Application.Current == null)
+                new Application { ShutdownMode = ShutdownMode.OnExplicitShutdown };
+            var md = Application.Current.Resources.MergedDictionaries;
+            if (md.Count == 0)
+            {
+                const string asm = "/VideoDownloader;component";
+                md.Add(new ResourceDictionary { Source = new Uri(asm + "/Themes/Dark.xaml", UriKind.Relative) });
+                md.Add(new ResourceDictionary { Source = new Uri(asm + "/Themes/Shared.xaml", UriKind.Relative) });
+            }
+            if (!Application.Current.Resources.Contains("InverseCountToVisibility"))
+                Application.Current.Resources["InverseCountToVisibility"] = new InverseCountToVisibilityConverter();
+            _initialized = true;
+        });
+    }
+}