fix: proxy absolute same-origin preview requests

Fixes Preview backend calls built from window.location.origin
Routes same-origin fetch, XHR, EventSource, and WebSocket requests through the preview proxy
Keeps local full-stack apps working inside the Preview panel

packages/web/server/lib/preview/proxy-runtime.js

@@ -484,9 +484,35 @@ const PREVIEW_BRIDGE_SCRIPT = String.raw`(() => {
     };
 
     const proxiedUrl = (value) => {
-      if (typeof value !== 'string' || !value.startsWith('/')) return value;
-      if (!shouldProxyPath(value)) return value;
-      return proxyBase + value;
+      if (typeof value !== 'string') return value;
+      if (value.startsWith('/')) {
+        if (!shouldProxyPath(value)) return value;
+        return proxyBase + value;
+      }
+
+      try {
+        const parsed = new URL(value, window.location.href);
+        if (parsed.origin === window.location.origin && shouldProxyPath(parsed.pathname)) {
+          return proxyBase + parsed.pathname + parsed.search + parsed.hash;
+        }
+      } catch {}
+
+      return value;
+    };
+
+    const proxiedWebSocketUrl = (value) => {
+      if (typeof value !== 'string') return value;
+      try {
+        const parsed = new URL(value, window.location.href);
+        const current = new URL(window.location.href);
+        const sameHost = parsed.host === current.host;
+        const isWebSocketProtocol = parsed.protocol === 'ws:' || parsed.protocol === 'wss:';
+        if (sameHost && isWebSocketProtocol && shouldProxyPath(parsed.pathname)) {
+          parsed.pathname = proxyBase + parsed.pathname;
+          return parsed.toString();
+        }
+      } catch {}
+      return value;
     };
 
     if (typeof window.fetch === 'function') {
@@ -529,6 +555,20 @@ const PREVIEW_BRIDGE_SCRIPT = String.raw`(() => {
       Object.defineProperty(OpenChamberPreviewEventSource, 'name', { value: 'EventSource' });
       window.EventSource = OpenChamberPreviewEventSource;
     }
+
+    if (typeof window.WebSocket === 'function') {
+      const NativeWebSocket = window.WebSocket;
+      function OpenChamberPreviewAppWebSocket(url, protocols) {
+        const nextUrl = proxiedWebSocketUrl(String(url));
+        return arguments.length === 1
+          ? new NativeWebSocket(nextUrl)
+          : new NativeWebSocket(nextUrl, protocols);
+      }
+      OpenChamberPreviewAppWebSocket.prototype = NativeWebSocket.prototype;
+      Object.setPrototypeOf(OpenChamberPreviewAppWebSocket, NativeWebSocket);
+      Object.defineProperty(OpenChamberPreviewAppWebSocket, 'name', { value: 'WebSocket' });
+      window.WebSocket = OpenChamberPreviewAppWebSocket;
+    }
   };
 
   const selectorPart = (element) => {