fix(chat): 阻止同会话并发 Agent Run 导致消息错乱

前端 submit 改用 chatStateRef 同步拦截连发；后端 createRun 检测同 session 活跃任务并返回 409，避免多条回复交错落库。

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

agent-run-gateway.mjs

@@ -340,6 +340,23 @@ export function createAgentRunGateway({
       return projectRun(existing);
     }
 
+    // Prevent multiple concurrent agent runs on the same Goose session, which would
+    // cause replies to arrive out of order and appear garbled in the chat UI.
+    if (sessionId && !isDirectChatSessionId(sessionId)) {
+      const [activeRows] = await pool.query(
+        `SELECT id FROM h5_agent_runs
+         WHERE agent_session_id = ? AND status NOT IN ('succeeded', 'failed')
+         LIMIT 1`,
+        [sessionId],
+      );
+      if (activeRows.length > 0) {
+        const conflict = new Error('该会话有正在处理的任务，请等待完成后再发送');
+        conflict.code = 'SESSION_RUN_CONFLICT';
+        conflict.status = 409;
+        throw conflict;
+      }
+    }
+
     const runId = crypto.randomUUID();
     const createdAt = nowMs();
     const runMessage = withRunMetadata(userMessage, {