fix(hub): stop instance iframe nav flash after account status badge

Load account_risk_badge.css before body paint, skip redundant hub theme re-apply, remove iframe hide overlay, and disable badge transitions in hub embed.

Co-authored-by: Cursor <cursoragent@cursor.com>

static/instance_theme.js

@@ -63,6 +63,7 @@
   }
 
   let _linkedTheme = null;
+  let _appliedTheme = null;
 
   function get() {
     if (isHubLinked()) {
@@ -191,13 +192,25 @@
     const options = opts || {};
     const linked = isHubLinked();
     const t = normalize(theme);
+    const root = document.documentElement;
+    const unchanged =
+      !options.force &&
+      _appliedTheme === t &&
+      root.getAttribute("data-theme") === t;
+    if (unchanged) {
+      return t;
+    }
+    _appliedTheme = t;
     if (linked) {
       _linkedTheme = t;
       writeLinkedThemeStorage(t);
-    } else if (!options.skipStore) {
+      root.setAttribute("data-hub-linked", "1");
+    } else {
+      root.removeAttribute("data-hub-linked");
+    }
+    if (!linked && !options.skipStore) {
       setStandalone(t);
     }
-    const root = document.documentElement;
     root.setAttribute("data-theme", t);
     const meta = document.querySelector('meta[name="theme-color"]');
     if (meta) meta.setAttribute("content", META[t]);
@@ -283,20 +296,6 @@
     apply(data.theme, { skipStore: true });
   }
 
-  function notifyParentFrameNavStart() {
-    if (!isHubLinked()) return;
-    try {
-      window.parent.postMessage({ type: "instance-frame-navigating", theme: get() }, "*");
-    } catch (_) {}
-  }
-
-  function notifyParentFrameReady() {
-    if (!isHubLinked()) return;
-    try {
-      window.parent.postMessage({ type: "instance-frame-ready" }, "*");
-    } catch (_) {}
-  }
-
   /** 中控 iframe 内：拦截顶栏导航，fetch 后 document.write 原地换页，避免 iframe 卸载白屏 */
   function initHubEmbedInFrameNav() {
     if (!isHubLinked()) return;
@@ -310,7 +309,6 @@
 
     async function navigateInFrame(href, opts) {
       const token = ++navToken;
-      notifyParentFrameNavStart();
       try {
         const r = await fetch(href, { credentials: "same-origin" });
         if (token !== navToken) return;
@@ -320,9 +318,6 @@
         }
         const html = await r.text();
         if (token !== navToken) return;
-        document.open();
-        document.write(html);
-        document.close();
         let path = href;
         try {
           const u = new URL(href, location.href);
@@ -330,6 +325,9 @@
         } catch (_) {}
         if (opts && opts.replace) history.replaceState(null, "", path);
         else history.pushState(null, "", path);
+        document.open();
+        document.write(html);
+        document.close();
       } catch (_) {
         if (token === navToken) location.href = href;
       }
@@ -368,7 +366,6 @@
       apply(get(), { skipStore: true });
       window.addEventListener("message", (ev) => initFromHubMessage(ev.data));
       initHubEmbedInFrameNav();
-      notifyParentFrameReady();
       try {
         window.parent.postMessage({ type: "instance-theme-ready" }, "*");
       } catch (_) {}