feat(openai): 极致优化 OAuth 链路并补齐性能守护

- 优化 /v1/responses 热路径，减少重复解析与不必要拷贝\n- 优化并发与 token 竞争路径并补齐运行指标\n- 补充 OpenAI/Ops 相关单元测试与回归用例\n- 新增灰度阈值守护与压测脚本，支撑发布验收

tools/perf/openai_oauth_responses_k6.js

@@ -0,0 +1,122 @@
+import http from 'k6/http';
+import { check } from 'k6';
+import { Rate, Trend } from 'k6/metrics';
+
+const baseURL = __ENV.BASE_URL || 'http://127.0.0.1:5231';
+const apiKey = __ENV.API_KEY || '';
+const model = __ENV.MODEL || 'gpt-5';
+const timeout = __ENV.TIMEOUT || '180s';
+
+const nonStreamRPS = Number(__ENV.NON_STREAM_RPS || 8);
+const streamRPS = Number(__ENV.STREAM_RPS || 4);
+const duration = __ENV.DURATION || '3m';
+const preAllocatedVUs = Number(__ENV.PRE_ALLOCATED_VUS || 30);
+const maxVUs = Number(__ENV.MAX_VUS || 200);
+
+const reqDurationMs = new Trend('openai_oauth_req_duration_ms', true);
+const ttftMs = new Trend('openai_oauth_ttft_ms', true);
+const non2xxRate = new Rate('openai_oauth_non2xx_rate');
+const streamDoneRate = new Rate('openai_oauth_stream_done_rate');
+
+export const options = {
+  scenarios: {
+    non_stream: {
+      executor: 'constant-arrival-rate',
+      rate: nonStreamRPS,
+      timeUnit: '1s',
+      duration,
+      preAllocatedVUs,
+      maxVUs,
+      exec: 'runNonStream',
+      tags: { request_type: 'non_stream' },
+    },
+    stream: {
+      executor: 'constant-arrival-rate',
+      rate: streamRPS,
+      timeUnit: '1s',
+      duration,
+      preAllocatedVUs,
+      maxVUs,
+      exec: 'runStream',
+      tags: { request_type: 'stream' },
+    },
+  },
+  thresholds: {
+    openai_oauth_non2xx_rate: ['rate<0.01'],
+    openai_oauth_req_duration_ms: ['p(95)<3000', 'p(99)<6000'],
+    openai_oauth_ttft_ms: ['p(99)<1200'],
+    openai_oauth_stream_done_rate: ['rate>0.99'],
+  },
+};
+
+function buildHeaders() {
+  const headers = {
+    'Content-Type': 'application/json',
+    'User-Agent': 'codex_cli_rs/0.1.0',
+  };
+  if (apiKey) {
+    headers.Authorization = `Bearer ${apiKey}`;
+  }
+  return headers;
+}
+
+function buildBody(stream) {
+  return JSON.stringify({
+    model,
+    stream,
+    input: [
+      {
+        role: 'user',
+        content: [
+          {
+            type: 'input_text',
+            text: '请返回一句极短的话：pong',
+          },
+        ],
+      },
+    ],
+    max_output_tokens: 32,
+  });
+}
+
+function recordMetrics(res, stream) {
+  reqDurationMs.add(res.timings.duration, { request_type: stream ? 'stream' : 'non_stream' });
+  ttftMs.add(res.timings.waiting, { request_type: stream ? 'stream' : 'non_stream' });
+  non2xxRate.add(res.status < 200 || res.status >= 300, { request_type: stream ? 'stream' : 'non_stream' });
+
+  if (stream) {
+    const done = !!res.body && res.body.indexOf('[DONE]') >= 0;
+    streamDoneRate.add(done, { request_type: 'stream' });
+  }
+}
+
+function postResponses(stream) {
+  const url = `${baseURL}/v1/responses`;
+  const res = http.post(url, buildBody(stream), {
+    headers: buildHeaders(),
+    timeout,
+    tags: { endpoint: '/v1/responses', request_type: stream ? 'stream' : 'non_stream' },
+  });
+
+  check(res, {
+    'status is 2xx': (r) => r.status >= 200 && r.status < 300,
+  });
+
+  recordMetrics(res, stream);
+  return res;
+}
+
+export function runNonStream() {
+  postResponses(false);
+}
+
+export function runStream() {
+  postResponses(true);
+}
+
+export function handleSummary(data) {
+  return {
+    stdout: `\nOpenAI OAuth /v1/responses 基线完成\n${JSON.stringify(data.metrics, null, 2)}\n`,
+    'docs/perf/openai-oauth-k6-summary.json': JSON.stringify(data, null, 2),
+  };
+}