feat(agent): 聊天提交统一走 POST /agent/runs 异步网关

引入 Agent Run 网关替代直连 /sessions/:id/reply，并在 api_lockdown 白名单中放行新入口，避免策略拦截导致聊天不可用。

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

src/api/client.ts

@@ -51,6 +51,21 @@ import { normalizeConversationMessages, normalizeUserMessageForApi } from '../ut
 
 const API = '/api';
 const DEFAULT_API_TIMEOUT_MS = 20_000;
+const AGENT_RUNS_PATH = '/agent/runs';
+
+export type AgentRun = {
+  id: string;
+  userId: string;
+  sessionId: string | null;
+  requestId: string;
+  status: 'queued' | 'running' | 'retryable' | 'succeeded' | 'failed';
+  attempts: number;
+  error: string | null;
+  createdAt: number;
+  updatedAt: number;
+  startedAt: number | null;
+  completedAt: number | null;
+};
 
 export class ApiError extends Error {
   readonly status: number;
@@ -2038,18 +2053,25 @@ export async function loadSessionDetail(
   return { session: detail, messages };
 }
 
-export async function sendReply(
-  sessionId: string,
+export async function createAgentRun(
+  sessionId: string | null,
   requestId: string,
   userMessage: Message,
-): Promise<void> {
-  await apiFetch(`${sessionPath(sessionId)}/reply`, {
+): Promise<AgentRun> {
+  const result = await apiFetch<{ run: AgentRun }>(AGENT_RUNS_PATH, {
     method: 'POST',
     body: JSON.stringify({
+      session_id: sessionId,
       request_id: requestId,
       user_message: normalizeUserMessageForApi(userMessage),
     }),
   });
+  return result.run;
+}
+
+export async function getAgentRun(runId: string): Promise<AgentRun> {
+  const result = await apiFetch<{ run: AgentRun }>(`${AGENT_RUNS_PATH}/${encodeURIComponent(runId)}`);
+  return result.run;
 }
 
 export async function cancelRequest(sessionId: string, requestId: string): Promise<void> {