fix: fallback to JS navigation when CDP Page.navigate fails

Some SPAs (X/Twitter) detect CDP Page.navigate and serve 'JavaScript
not available' error pages. Added _retryWithJsNavIfBroken() that
detects these specific anti-bot error pages and retries via JS
window.location.href, triggering the SPA router instead.

Detection is strict (only on definitive error text like 'JavaScript
is not available') to avoid false positives on slow-loading pages.

Also skip redundant Page.navigate when the tab is already on the
exact target URL.

Author: charliewwdev

lib/src/cli/serve.dart

@@ -242,13 +242,19 @@ Future<void> _navigateToUrl(CdpDriver cdp, String url, int cdpPort) async {
         await cdp.reconnectTo(wsUrl);
         print('   ✅ Connected to existing tab: ${matchingTab['url']}');
       }
-      // Navigate within this tab to the exact URL
-      await cdp.call('Page.navigate', {'url': url});
-      await Future.delayed(const Duration(seconds: 3));
+      // Only navigate if the tab isn't already on the exact URL
+      final tabUrl = matchingTab['url'] as String? ?? '';
+      if (tabUrl != url) {
+        await cdp.call('Page.navigate', {'url': url});
+        await Future.delayed(const Duration(seconds: 3));
+        // Fallback: if page is broken (SPA anti-bot), retry via JS navigation
+        await _retryWithJsNavIfBroken(cdp, url);
+      }
     } else {
       // No matching tab — navigate in current tab
       await cdp.call('Page.navigate', {'url': url});
       await Future.delayed(const Duration(seconds: 3));
+      await _retryWithJsNavIfBroken(cdp, url);
       print('   ✅ Navigated current tab to: $url');
     }
   } catch (e) {
@@ -258,6 +264,37 @@ Future<void> _navigateToUrl(CdpDriver cdp, String url, int cdpPort) async {
   }
 }
 
+/// Some SPAs (X/Twitter) detect CDP Page.navigate and serve static error pages
+/// like "JavaScript is not available". If detected, retry via JS navigation
+/// which triggers the SPA router instead of a full page reload.
+/// Only triggers on definitive anti-bot error pages, NOT on slow-loading pages.
+Future<void> _retryWithJsNavIfBroken(CdpDriver cdp, String url) async {
+  try {
+    final result = await cdp.evaluate('''
+      (() => {
+        const text = document.body?.innerText || '';
+        // Only retry on definitive anti-bot/broken-JS error pages
+        if (text.includes('JavaScript is not available') ||
+            text.includes('Enable JavaScript') ||
+            text.includes('JavaScript is disabled') ||
+            text.includes('browser is not supported')) {
+          return 'broken';
+        }
+        return 'ok';
+      })()
+    ''');
+    final status = result['result']?['value'] as String? ?? 'ok';
+    if (status == 'broken') {
+      print('   ⚠️ Anti-bot error page detected, retrying via JS navigation...');
+      final escaped = url.replaceAll("'", "\\'");
+      await cdp.evaluate("window.location.href = '$escaped'");
+      await Future.delayed(const Duration(seconds: 4));
+    }
+  } catch (_) {
+    // Ignore errors in detection — non-critical
+  }
+}
+
 /// Handle HTTP requests
 Future<void> _handleRequest(
   HttpRequest request,