diff --git a/packages/genui/a2ui-playground/lynx-src/a2ui/App.tsx b/packages/genui/a2ui-playground/lynx-src/a2ui/App.tsx
index 5a4d6fd7a5..c2f2ae8e42 100644
--- a/packages/genui/a2ui-playground/lynx-src/a2ui/App.tsx
+++ b/packages/genui/a2ui-playground/lynx-src/a2ui/App.tsx
@@ -120,6 +120,20 @@ function parseJsonLikeString(input: string): unknown {
   return input;
 }
 
+function decodeUrlString(input: string): string {
+  let current = input;
+  for (let i = 0; i < 3; i++) {
+    try {
+      const decoded = decodeURIComponent(current);
+      if (decoded === current) break;
+      current = decoded;
+    } catch {
+      break;
+    }
+  }
+  return current;
+}
+
 function normalizeInitDataLike(raw: unknown): InitData {
   if (raw === null || raw === undefined) return {};
   if (typeof raw !== 'object') return {};
@@ -128,10 +142,14 @@ function normalizeInitDataLike(raw: unknown): InitData {
   const out: InitData = {};
 
   const messagesUrl = obj.messagesUrl;
-  if (typeof messagesUrl === 'string') out.messagesUrl = messagesUrl;
+  if (typeof messagesUrl === 'string') {
+    out.messagesUrl = decodeUrlString(messagesUrl);
+  }
 
   const actionMocksUrl = obj.actionMocksUrl;
-  if (typeof actionMocksUrl === 'string') out.actionMocksUrl = actionMocksUrl;
+  if (typeof actionMocksUrl === 'string') {
+    out.actionMocksUrl = decodeUrlString(actionMocksUrl);
+  }
 
   const messages = obj.messages;
   if (messages !== undefined) {
diff --git a/packages/genui/a2ui-playground/src/components/PreviewPanel.tsx b/packages/genui/a2ui-playground/src/components/PreviewPanel.tsx
index 327f899862..86d1bad03f 100644
--- a/packages/genui/a2ui-playground/src/components/PreviewPanel.tsx
+++ b/packages/genui/a2ui-playground/src/components/PreviewPanel.tsx
@@ -352,71 +352,6 @@ export function PreviewPanel(props: PreviewPanelProps) {
         }
       }
       setLynxDevUrl(uInline.toString());
-
-      void (async () => {
-        try {
-          const rspeedyOrigin = new URL(rspeedyDevUrl).origin;
-          const res = await window.fetch(`${rspeedyOrigin}/__a2ui_payload`, {
-            method: 'POST',
-            headers: { 'Content-Type': 'application/json' },
-            body: JSON.stringify({
-              messages: previewSource.messages,
-              actionMocks: previewSource.actionMocks,
-            }),
-          });
-          if (!res.ok) return;
-          const data = (await res.json()) as {
-            messagesUrl?: string;
-            actionMocksUrl?: string;
-          };
-
-          if (seq !== buildSeqRef.current) return;
-
-          const messagesUrlAbs = typeof data.messagesUrl === 'string'
-            ? `${rspeedyOrigin}${data.messagesUrl}`
-            : undefined;
-          const actionMocksUrlAbs = typeof data.actionMocksUrl === 'string'
-            ? `${rspeedyOrigin}${data.actionMocksUrl}`
-            : undefined;
-
-          if (messagesUrlAbs) {
-            const buildStoredPayloadRenderUrl = (targetBaseUrl: string) => {
-              const r = new URL('render.html', targetBaseUrl);
-              r.searchParams.set('protocol', previewSource.protocol.name);
-              r.searchParams.set(
-                'demoUrl',
-                previewSource.demoUrl ?? DEFAULT_A2UI_DEMO_URL,
-              );
-              r.searchParams.set('theme', previewSource.theme);
-              r.searchParams.set('messagesUrl', messagesUrlAbs);
-              if (actionMocksUrlAbs && previewSource.actionMocks) {
-                r.searchParams.set('actionMocksUrl', actionMocksUrlAbs);
-              }
-              if (speed !== 1) {
-                r.searchParams.set('speed', String(speed));
-              }
-              return r.toString();
-            };
-            setRenderUrl(buildStoredPayloadRenderUrl(baseUrl));
-            setRenderShareUrl(buildStoredPayloadRenderUrl(shareBaseUrl));
-          }
-
-          const u = new URL(rspeedyDevUrl);
-          if (speed !== 1) u.searchParams.set('speed', String(speed));
-          u.searchParams.set('theme', previewSource.theme);
-          if (messagesUrlAbs) {
-            u.searchParams.set('messagesUrl', messagesUrlAbs);
-          }
-          if (actionMocksUrlAbs && previewSource.actionMocks) {
-            u.searchParams.set('actionMocksUrl', actionMocksUrlAbs);
-          }
-          u.searchParams.delete('messages');
-          u.searchParams.delete('actionMocks');
-          setLynxDevUrl(u.toString());
-        } catch {
-          // Keep the inline URLs above if shortening is unavailable.
-        }
-      })();
       return;
     }