[release/10.0.1xx] [Blazor][HotReload] Include refresh script for enhanced navigation (#50580)

Co-authored-by: Marek Fišera <[email protected]>

Author: github-actions[bot]

src/BuiltInTools/BrowserRefresh/BrowserRefreshMiddleware.cs

@@ -164,7 +164,8 @@ internal static bool IsBrowserDocumentRequest(HttpContext context)
 
             if (request.Headers.TryGetValue("Sec-Fetch-Dest", out var values) &&
                 !StringValues.IsNullOrEmpty(values) &&
-                !string.Equals(values[0], "document", StringComparison.OrdinalIgnoreCase))
+                !string.Equals(values[0], "document", StringComparison.OrdinalIgnoreCase) &&
+                !IsProgressivelyEnhancedNavigation(context.Request))
             {
                 // See https://github.com/dotnet/aspnetcore/issues/37326.
                 // Only inject scripts that are destined for a browser page.
@@ -188,6 +189,14 @@ internal static bool IsBrowserDocumentRequest(HttpContext context)
             return false;
         }
 
+        private static bool IsProgressivelyEnhancedNavigation(HttpRequest request)
+        {
+            // This is an exact copy from https://github.com/dotnet/aspnetcore/blob/bb2d778dc66aa998ea8e26db0e98e7e01423ff78/src/Components/Endpoints/src/Rendering/EndpointHtmlRenderer.Streaming.cs#L327-L332
+            // For enhanced nav, the Blazor JS code controls the "accept" header precisely, so we can be very specific about the format
+            var accept = request.Headers.Accept;
+            return accept.Count == 1 && string.Equals(accept[0]!, "text/html; blazor-enhanced-nav=on", StringComparison.Ordinal);
+        }
+
         internal void Test_SetEnvironment(string dotnetModifiableAssemblies, string aspnetcoreBrowserTools)
         {
             _dotnetModifiableAssemblies = dotnetModifiableAssemblies;