fix(webview): render inline HTML on web instead of permanent Loading state

modules/ensemble/lib/widget/webview/web/webviewstate.dart

@@ -30,6 +30,18 @@ class WebViewState extends EWidgetState<EnsembleWebView> {
     // widget.controller.webViewController = ControllerImpl(_iframeElement);
   }
 
+  @override
+  void didUpdateWidget(covariant EnsembleWebView oldWidget) {
+    super.didUpdateWidget(oldWidget);
+    if (oldWidget.controller.url != widget.controller.url ||
+        oldWidget.controller.html != widget.controller.html ||
+        oldWidget.controller.htmlBaseUrl != widget.controller.htmlBaseUrl ||
+        oldWidget.controller.injectedJavaScript !=
+            widget.controller.injectedJavaScript) {
+      _loadIframeContent();
+    }
+  }
+
   @override
   void dispose() {
     _cleanupIFrame();
@@ -45,10 +57,9 @@ class WebViewState extends EWidgetState<EnsembleWebView> {
   HtmlElementView buildIFrameWidget() {
     _iframeElement.style.width = '100%';
     _iframeElement.style.height = '100%';
-
-    _iframeElement.src = widget.controller.url ?? '';
     _iframeElement.style.border = 'none';
 
+    _loadIframeContent();
     _setupJavaScriptChannels();
 
     // ignore: undefined_prefixed_name
@@ -63,6 +74,22 @@ class WebViewState extends EWidgetState<EnsembleWebView> {
     );
   }
 
+  void _loadIframeContent() {
+    final html = widget.controller.html;
+    if (html != null && html.isNotEmpty) {
+      _iframeElement.removeAttribute('src');
+      _iframeElement.srcdoc = buildIframeHtmlDocument(
+        html: html,
+        htmlBaseUrl: widget.controller.htmlBaseUrl,
+        injectedJavaScript: widget.controller.injectedJavaScript,
+      );
+      return;
+    }
+
+    _iframeElement.removeAttribute('srcdoc');
+    _iframeElement.src = widget.controller.url ?? '';
+  }
+
   void _setupJavaScriptChannels() {
     window.addEventListener('message', (event) {
       if (event is MessageEvent) {
@@ -72,7 +99,13 @@ class WebViewState extends EWidgetState<EnsembleWebView> {
   }
 
   void _handleWebMessage(MessageEvent event) {
-    if (event.origin != Uri.parse(widget.controller.url ?? '').origin) {
+    final expectedOrigin = resolvedWebViewOrigin(
+      url: widget.controller.url,
+      htmlBaseUrl: widget.controller.htmlBaseUrl,
+    );
+    if (expectedOrigin != null &&
+        expectedOrigin.isNotEmpty &&
+        event.origin != expectedOrigin) {
       return;
     }
 
@@ -106,10 +139,14 @@ class WebViewState extends EWidgetState<EnsembleWebView> {
     }
   }
 
+  bool get _hasContent =>
+      (widget.controller.url != null && widget.controller.url!.isNotEmpty) ||
+      (widget.controller.html != null && widget.controller.html!.isNotEmpty);
+
   @override
   Widget buildWidget(BuildContext context) {
     // WebView's height will be the same as the HTML height
-    if (widget.controller.url == null) {
+    if (!_hasContent) {
       return const Text('Loading...');
     }
     return SizedBox(height: widget.controller.height, child: htmlView!);

modules/ensemble/lib/widget/webview/webview.dart

@@ -219,6 +219,48 @@ Map<String, String> parseYamlMap(value) {
   return result;
 }
 
+/// Default base URL for inline HTML WebViews when [htmlBaseUrl] is not set.
+const String kWebViewHtmlDefaultBaseUrl = 'https://ensemble.local/';
+
+/// Resolve the expected postMessage origin for a WebView URL or inline HTML base.
+@visibleForTesting
+String? resolvedWebViewOrigin({String? url, String? htmlBaseUrl}) {
+  if (url != null && url.isNotEmpty) {
+    return Uri.tryParse(url)?.origin;
+  }
+  final base = htmlBaseUrl?.trim();
+  return Uri.tryParse(
+    (base == null || base.isEmpty) ? kWebViewHtmlDefaultBaseUrl : base,
+  )?.origin;
+}
+
+/// Build a full HTML document for iframe `srcdoc` rendering on web.
+@visibleForTesting
+String buildIframeHtmlDocument({
+  required String html,
+  String? htmlBaseUrl,
+  String? injectedJavaScript,
+}) {
+  final base = htmlBaseUrl?.trim();
+  final resolvedBase = (base == null || base.isEmpty)
+      ? kWebViewHtmlDefaultBaseUrl
+      : base;
+  final buffer = StringBuffer()
+    ..write('<!DOCTYPE html><html><head><base href="')
+    ..write(_escapeHtmlAttribute(resolvedBase))
+    ..write('"></head><body>')
+    ..write(html);
+  final script = injectedJavaScript?.trim();
+  if (script != null && script.isNotEmpty) {
+    buffer.write('<script>$script</script>');
+  }
+  buffer.write('</body></html>');
+  return buffer.toString();
+}
+
+String _escapeHtmlAttribute(String value) =>
+    value.replaceAll('&', '&amp;').replaceAll('"', '&quot;');
+
 enum HeaderMatchType { CONTAINS, EXACT, REGEX }
 class HeaderOverrideRule {
   final String urlPattern;

modules/ensemble/test/webview_html_content_test.dart

@@ -0,0 +1,54 @@
+import 'package:ensemble/widget/webview/webview.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  group('inline WebView HTML helpers', () {
+    test('resolvedWebViewOrigin prefers url over html base', () {
+      expect(
+        resolvedWebViewOrigin(
+          url: 'https://example.com/page',
+          htmlBaseUrl: 'https://ignored.test/',
+        ),
+        'https://example.com',
+      );
+    });
+
+    test('resolvedWebViewOrigin falls back to html base url', () {
+      expect(
+        resolvedWebViewOrigin(htmlBaseUrl: 'https://cdn.example/app/'),
+        'https://cdn.example',
+      );
+    });
+
+    test('resolvedWebViewOrigin uses default base for inline html', () {
+      expect(
+        resolvedWebViewOrigin(),
+        Uri.parse(kWebViewHtmlDefaultBaseUrl).origin,
+      );
+    });
+
+    test('buildIframeHtmlDocument wraps html with base and injected script', () {
+      final document = buildIframeHtmlDocument(
+        html: '<p>Hello</p>',
+        htmlBaseUrl: 'https://app.example/',
+        injectedJavaScript: 'console.log("ready");',
+      );
+
+      expect(document, contains('<base href="https://app.example/">'));
+      expect(document, contains('<p>Hello</p>'));
+      expect(document, contains('<script>console.log("ready");</script>'));
+    });
+
+    test('buildIframeHtmlDocument escapes base url attribute characters', () {
+      final document = buildIframeHtmlDocument(
+        html: '<p>Hi</p>',
+        htmlBaseUrl: 'https://app.example/path?a=1&b=2"',
+      );
+
+      expect(
+        document,
+        contains('<base href="https://app.example/path?a=1&amp;b=2&quot;">'),
+      );
+    });
+  });
+}