diff --git a/design/prototype/serve.mjs b/design/prototype/serve.mjs
index de7d6c2..7e56bca 100644
--- a/design/prototype/serve.mjs
+++ b/design/prototype/serve.mjs
@@ -20,24 +20,26 @@ const MIME = {
   '.woff2': 'font/woff2',
 };
 
-const clients = new Set();
+// 热重载改短轮询（2026-07-10）：原 SSE 每个 tab 一条常驻连接，Chrome 同域
+// HTTP/1.1 上限 6 条——开到第 7 个原型 tab 连接池耗尽整站卡死。轮询即用即断，无上限。
+let version = 0;
 const RELOAD_SNIPPET = `\n<script>
 (function(){ try{
-  var es=new EventSource('/__reload');
-  es.onmessage=function(){ location.reload(); };
+  var v=null;
+  function tick(){
+    fetch('/__version',{cache:'no-store'}).then(function(r){return r.json();}).then(function(j){
+      if(v!==null && j.v!==v){ location.reload(); return; }
+      v=j.v; setTimeout(tick,1500);
+    }).catch(function(){ setTimeout(tick,3000); });
+  }
+  tick();
 }catch(e){} })();
 </script>\n`;
 
 const server = http.createServer((req, res) => {
-  if (req.url === '/__reload') {
-    res.writeHead(200, {
-      'Content-Type': 'text/event-stream',
-      'Cache-Control': 'no-cache',
-      Connection: 'keep-alive',
-    });
-    res.write('retry: 500\n\n');
-    clients.add(res);
-    req.on('close', () => clients.delete(res));
+  if (req.url === '/__version' || req.url === '/__reload') {
+    res.writeHead(200, { 'Content-Type': 'application/json', 'Cache-Control': 'no-store' });
+    res.end(JSON.stringify({ v: version }));
     return;
   }
 
@@ -85,7 +87,7 @@ fs.watch(ROOT, { recursive: true }, (_ev, file) => {
   if (file && file.endsWith('serve.mjs')) return;
   clearTimeout(debounce);
   debounce = setTimeout(() => {
-    for (const c of clients) c.write('data: reload\n\n');
+    version++;
     if (file && /\.(html|css|js)$/.test(file)) runDsCheck();
   }, 80);
 });