fix(web): code review pass — scroll watch, SSE same-origin, store concurrency, modal reset, admin validation

web/src/views/chat/ChatDetailView.vue

@@ -150,8 +150,23 @@ onMounted(async () => {
   }
 })
 
+// 路由 conversationId 切换：在 /chat ↔ /chat/:id 同组件复用时同步状态。
 watch(
-  () => chat.messages.length,
+  () => route.params.conversationId,
+  async (cid) => {
+    if (typeof cid === 'string' && cid !== '') {
+      if (chat.currentConversation?.id !== cid) {
+        await chat.openConversation(cid)
+      }
+    } else {
+      chat.closeCurrent()
+    }
+  },
+)
+
+// 流式输出时 messages.length 不变，只 content 增长 —— 同时观察末消息内容长度。
+watch(
+  () => [chat.messages.length, chat.messages.at(-1)?.content?.length ?? 0],
   () => {
     nextTick(() => {
       const el = scrollEl.value