202 lines
7.2 KiB
TypeScript
202 lines
7.2 KiB
TypeScript
/**
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* Mock LLM Server — E2E 冒烟测试的本地 OpenAI 兼容 Provider（v0.8.1 P2-5）
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*
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* 实现 DeepSeek 适配器实际消费的最小协议面：
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* - POST {baseURL}/chat/completions（stream=true）：按 SSE 推送一段固定文本 +
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* finish_reason=stop + usage + [DONE]；
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* - POST /chat/completions（stream=false）：非流式 JSON（压缩摘要等内部调用兜底）。
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*
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* v0.8.2 P3-3: 新增两条可控脚本（内容标记协议，零外部依赖）：
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* - `__E2E_TOOL_CALL__`：返回 tool_calls（think 工具）；后续请求带 tool 消息时
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* 返回最终文本 —— 锁定"多轮工具调用 → 观察 → 最终回答"全链路；
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* - `__E2E_HANG__`：推送首帧后挂起连接（不结束、不推 finish_reason）——
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* 供中断链路测试：客户端 abort 时服务端感知连接关闭。
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*
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* 端口随机分配（127.0.0.1），测试结束关闭 —— 不触外网、不落真实会话数据。
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*/
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import { createServer, type Server } from 'http';
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import type { AddressInfo } from 'net';
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/** 流式回复的固定文本（断言锚点） */
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export const MOCK_REPLY = 'Hello from mock LLM. E2E smoke reply.';
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/** 多轮工具调用脚本的最终回复（断言锚点） */
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export const TOOL_REPLY = 'Tool flow completed OK.';
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/** 中断脚本的流式前缀（挂起前推送的第一帧文本） */
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export const HANG_PREFIX = 'Hanging stream...';
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export interface MockLLMHandle {
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url: string;
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close: () => Promise<void>;
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/** 收到的 chat/completions 请求体列表（断言用） */
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readonly requests: Array<Record<string, unknown>>;
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}
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function frame(res: import('http').ServerResponse, payload: Record<string, unknown>): void {
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res.write(`data: ${JSON.stringify(payload)}\n\n`);
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}
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export function startMockLLM(): Promise<MockLLMHandle> {
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const requests: Array<Record<string, unknown>> = [];
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const server: Server = createServer((req, res) => {
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if (!req.url?.includes('/chat/completions')) {
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res.writeHead(404).end();
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return;
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}
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let body = '';
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req.on('data', (chunk) => {
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body += chunk;
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});
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req.on('end', () => {
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let parsed: Record<string, unknown> = {};
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try {
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parsed = JSON.parse(body) as Record<string, unknown>;
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} catch {
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/* 忽略解析失败 */
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}
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requests.push(parsed);
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const isStream = parsed.stream === true;
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const messages = (parsed.messages as Array<Record<string, unknown>>) ?? [];
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const hasToolResult = messages.some((m) => m.role === 'tool');
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// 脚本标记只看**最后一条用户消息**：恢复请求的历史里会带着早前的
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// __E2E_HANG__ 消息，若按全量 JSON 匹配会把恢复请求也误判为挂起脚本。
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const lastUserContent = [...messages]
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.reverse()
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.find((m) => m.role === 'user');
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const lastUserText = typeof lastUserContent?.content === 'string' ? lastUserContent.content : '';
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const wantsToolCall = lastUserText.includes('__E2E_TOOL_CALL__') && !hasToolResult;
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const wantsHang = lastUserText.includes('__E2E_HANG__');
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if (!isStream) {
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res.writeHead(200, { 'Content-Type': 'application/json' });
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res.end(
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JSON.stringify({
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id: 'mock-1',
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model: parsed.model ?? 'mock',
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choices: [
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{
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index: 0,
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message: { role: 'assistant', content: MOCK_REPLY },
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finish_reason: 'stop',
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},
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],
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usage: { prompt_tokens: 10, completion_tokens: 8, total_tokens: 18 },
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}),
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);
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return;
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}
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res.writeHead(200, {
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'Content-Type': 'text/event-stream',
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'Cache-Control': 'no-cache',
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Connection: 'keep-alive',
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});
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// ===== 中断脚本：首帧后挂起，客户端 abort 时感知连接关闭 =====
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if (wantsHang) {
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frame(res, {
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id: 'mock-hang',
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model: parsed.model ?? 'mock',
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choices: [{ index: 0, delta: { role: 'assistant', content: HANG_PREFIX } }],
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});
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// 挂起即可：不推 finish_reason、不 [DONE]、不 end。
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// 注意不要监听 req 'close' —— Node>=16 该事件在请求体接收完成时即触发
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//（非连接关闭），主动 destroy 会把挂起变成 'terminated' 断流。
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// 客户端 abort 时 socket 关闭由 HTTP 栈自然回收。
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// 心跳：每秒发一条 SSE 注释行（':' 前缀，解析器按非 data 帧忽略）——
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// 保持连接健康，防止 keep-alive/空闲机制把"挂起"变成提前断流，
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// 使中断测试与引擎 ERROR 收尾产生竞态。
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const heartbeat = setInterval(() => {
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try {
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res.write(': keepalive\n\n');
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} catch {
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clearInterval(heartbeat);
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}
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}, 1_000);
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heartbeat.unref?.();
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return;
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}
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// ===== 多轮工具调用脚本 =====
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if (wantsToolCall) {
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frame(res, {
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id: 'mock-tool',
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model: parsed.model ?? 'mock',
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choices: [
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{
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index: 0,
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delta: {
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role: 'assistant',
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tool_calls: [
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{
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index: 0,
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id: 'call_e2e_1',
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type: 'function',
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function: { name: 'think', arguments: '{"thought":"mock tool call"}' },
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},
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],
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},
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},
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],
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});
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frame(res, {
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id: 'mock-tool',
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model: parsed.model ?? 'mock',
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choices: [{ index: 0, delta: {}, finish_reason: 'tool_calls' }],
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usage: { prompt_tokens: 12, completion_tokens: 10, total_tokens: 22 },
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});
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res.write('data: [DONE]\n\n');
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res.end();
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return;
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}
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if (hasToolResult) {
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// 工具结果已回传 → 最终回答
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frame(res, {
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id: 'mock-tool-2',
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model: parsed.model ?? 'mock',
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choices: [{ index: 0, delta: { role: 'assistant', content: TOOL_REPLY } }],
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});
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frame(res, {
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id: 'mock-tool-2',
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model: parsed.model ?? 'mock',
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choices: [{ index: 0, delta: {}, finish_reason: 'stop' }],
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usage: { prompt_tokens: 20, completion_tokens: 8, total_tokens: 28 },
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});
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res.write('data: [DONE]\n\n');
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res.end();
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return;
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}
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// ===== 默认冒烟脚本 =====
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frame(res, {
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id: 'mock-1',
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model: parsed.model ?? 'mock',
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choices: [{ index: 0, delta: { role: 'assistant', content: MOCK_REPLY } }],
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});
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frame(res, {
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id: 'mock-1',
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model: parsed.model ?? 'mock',
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choices: [{ index: 0, delta: {}, finish_reason: 'stop' }],
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usage: { prompt_tokens: 10, completion_tokens: 8, total_tokens: 18 },
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});
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res.write('data: [DONE]\n\n');
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res.end();
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});
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});
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return new Promise((resolve) => {
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server.listen(0, '127.0.0.1', () => {
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const addr = server.address() as AddressInfo;
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resolve({
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url: `http://127.0.0.1:${addr.port}`,
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close: () => new Promise<void>((r) => server.close(() => r())),
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requests,
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});
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});
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});
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}
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