feat: hidden WebView2 window for authenticated API calls

windows/WebViewFetchWindow.cs

@@ -0,0 +1,59 @@
+using Microsoft.Web.WebView2.Core;
+using Microsoft.Web.WebView2.Wpf;
+using System;
+using System.IO;
+using System.Threading.Tasks;
+using System.Windows;
+
+namespace ClaudeCheckerWindows;
+
+// Invisible 1×1 window that hosts a WebView2 for authenticated API calls.
+// Uses the same user data folder as LoginWindow so the session is shared.
+internal sealed class WebViewFetchWindow : Window
+{
+    private readonly WebView2 _wv = new();
+
+    public WebViewFetchWindow()
+    {
+        Width          = 1;
+        Height         = 1;
+        Left           = -9999;
+        Top            = -9999;
+        ShowInTaskbar  = false;
+        WindowStyle    = WindowStyle.None;
+        AllowsTransparency = true;
+        Opacity        = 0;
+        Content        = _wv;
+    }
+
+    public async Task<string?> FetchAsync(string navigateUrl, string script, int timeoutMs = 20000)
+    {
+        var env = await CoreWebView2Environment.CreateAsync(userDataFolder:
+            Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData),
+                "ClaudeChecker", "WebView2"));
+
+        await _wv.EnsureCoreWebView2Async(env);
+
+        var tcs = new TaskCompletionSource<string?>();
+
+        EventHandler<CoreWebView2NavigationCompletedEventArgs>? handler = null;
+        handler = async (_, e) =>
+        {
+            _wv.CoreWebView2.NavigationCompleted -= handler;
+            if (!e.IsSuccess) { tcs.TrySetResult(null); return; }
+            try
+            {
+                var result = await _wv.CoreWebView2.ExecuteScriptAsync(script);
+                tcs.TrySetResult(result);
+            }
+            catch { tcs.TrySetResult(null); }
+        };
+
+        _wv.CoreWebView2.NavigationCompleted += handler;
+        _wv.CoreWebView2.Navigate(navigateUrl);
+
+        _ = Task.Delay(timeoutMs).ContinueWith(_ => tcs.TrySetResult(null));
+
+        return await tcs.Task;
+    }
+}