优化渲染引用处理，增加格式校验与说明；更新 agent 说明

src/routes/chat.ts

@@ -20,6 +20,8 @@ import {
   type SupportedModel,
 } from "./chatStream.js";
 
+const persistentRenderRefPattern = /^res-[a-z0-9-]+$/i;
+
 const payloadSchema = z.object({
   message: z.string().min(1).max(10000),
   session_id: z.string().max(128).optional(),
@@ -67,6 +69,13 @@ export const buildChatRouter = (
       return;
     }
 
+    if (!persistentRenderRefPattern.test(renderRef)) {
+      res.status(400).json({
+        message: "render_ref must be a persistent ref like res-..., not a file path",
+      });
+      return;
+    }
+
     const result = await resultReferenceStore.getFullAuthorized(renderRef, {
       actorKey: toActorKey(userId),
       clientSessionId,