diff --git a/tests/hs-run-filtered.js b/tests/hs-run-filtered.js
index 8a1406a0..4f32b557 100755
--- a/tests/hs-run-filtered.js
+++ b/tests/hs-run-filtered.js
@@ -528,9 +528,62 @@ class HsIntersectionObserver {
 }
 globalThis.IntersectionObserver = HsIntersectionObserver;
 globalThis.IntersectionObserverEntry = class {};
-globalThis.navigator={userAgent:'node'}; globalThis.location={href:'http://localhost/',pathname:'/',search:'',hash:''};
+globalThis.navigator={userAgent:'node'}; globalThis.location={href:'http://localhost/',pathname:'/',search:'',hash:'',protocol:'http:',host:'localhost',hostname:'localhost',port:''};
 globalThis.history={pushState(){},replaceState(){},back(){},forward(){}};
 globalThis.getSelection=()=>({toString:()=>(globalThis.__test_selection||'')});
+// HsWebSocket — cluster-36 WebSocket mock. Records every constructed socket
+// in globalThis.__hs_ws_created so tests can assert on URLs and sent frames.
+// Tests may override globalThis.WebSocket before activating hyperscript.
+globalThis.__hs_ws_created = [];
+globalThis.WebSocket = function HsWebSocket(url) {
+  const sock = {
+    url,
+    onmessage: null,
+    _listeners: {},
+    _sent: [],
+    send(msg) { sock._sent.push(msg); },
+    addEventListener(t, h) { (sock._listeners[t] = sock._listeners[t] || []).push(h); },
+    removeEventListener(t, h) { const a = sock._listeners[t]; if (a) { const i = a.indexOf(h); if (i >= 0) a.splice(i, 1); } },
+    close() { (sock._listeners['close'] || []).forEach(h => { try { h({}); } catch(_) {} }); }
+  };
+  globalThis.__hs_ws_created.push(sock);
+  return sock;
+};
+// _hs_make_rpc_proxy — cluster-36 RPC proxy factory. Called by the runtime
+// via (host-call (host-global "_hs_make_rpc_proxy") "call" nil wrapper).
+// wrapper is the SX dict: {raw, url, timeout, pending, ...}
+// Returns an ES6 Proxy whose property accesses dispatch RPC calls.
+function _hsRpcCall(wrapper, fnName, args, timeoutMs) {
+  return new Promise((resolve, reject) => {
+    const iid = String(Math.random()).slice(2) + String(Date.now());
+    if (!wrapper.pending) wrapper.pending = {};
+    wrapper.pending[iid] = { resolve, reject };
+    const raw = wrapper.raw;
+    const msg = JSON.stringify({ iid, function: fnName, args });
+    raw.send(msg);
+    const ms = timeoutMs === undefined ? (typeof wrapper.timeout === 'number' ? wrapper.timeout : 0) : timeoutMs;
+    if (ms !== Infinity && typeof ms === 'number') {
+      setTimeout(() => {
+        if (wrapper.pending && wrapper.pending[iid]) {
+          delete wrapper.pending[iid];
+          reject('Timed out');
+        }
+      }, ms);
+    }
+  });
+}
+function _hs_make_rpc_proxy(wrapper, overrides) {
+  overrides = overrides || {};
+  return new Proxy({}, {
+    get(_, name) {
+      if (['then', 'catch', 'length', 'toJSON'].includes(name)) return null;
+      if (name === 'noTimeout') return _hs_make_rpc_proxy(wrapper, Object.assign({}, overrides, { timeout: Infinity }));
+      if (name === 'timeout') return function(n) { return _hs_make_rpc_proxy(wrapper, Object.assign({}, overrides, { timeout: n })); };
+      return function(...args) { return _hsRpcCall(wrapper, name, args, overrides.timeout); };
+    }
+  });
+}
+globalThis._hs_make_rpc_proxy = { call: _hs_make_rpc_proxy };
 const _origLog = console.log;
 globalThis.console = { log: () => {}, error: () => {}, warn: () => {}, info: () => {}, debug: () => {} }; // suppress ALL console noise
 const _log = _origLog; // keep reference for our own output