feat: add SSE passthrough stream action

scripts/test-gateway-e2e.mjs

@@ -822,6 +822,7 @@ async function run() {
           retryable_error_messages: ["capacity test"],
           upstream_fetch_retry_attempts: 3,
           upstream_fetch_retry_backoff_ms: 50,
+          stream_action: "passthrough",
           endpoints: ["/responses", "/v1/responses"],
         }),
       },
@@ -829,6 +830,15 @@ async function run() {
     assert(exportableTextProfileResponse.status === 200, `可导出文本 profile 保存失败: ${exportableTextProfileResponse.status}`);
     const exportableTextProfilePayload = await exportableTextProfileResponse.json();
     assert(!JSON.stringify(exportableTextProfilePayload).includes("text-export-secret"), "普通 profile API 不应返回导出 key");
+    const exportableTextProfile = (exportableTextProfilePayload.profiles || []).find(
+      (profile) => profile?.name === "export-source",
+    );
+    assert(exportableTextProfile?.form?.stream_action === "passthrough", "文本 profile 未保留 SSE 直通模式");
+    assert(
+      (await readFile(path.join(profilesDir, "export-source.env"), "utf8"))
+        .includes("CODEX_RETRY_GATEWAY_STREAM_ACTION=passthrough"),
+      "文本 profile env 未写入 SSE 直通模式",
+    );
 
     const passthroughExportResponse = await fetch(
       `http://127.0.0.1:${gatewayPort}/__codex_retry_gateway/api/profiles/export`,
@@ -1916,6 +1926,59 @@ async function run() {
       }
     }
 
+    const enablePassthroughResponse = await fetch(`http://127.0.0.1:${gatewayPort}/__codex_retry_gateway/api/config`, {
+      method: "POST",
+      headers: { ...adminHeaders, "content-type": "application/json" },
+      body: JSON.stringify({ stream_action: "passthrough" }),
+    });
+    const enablePassthroughPayload = await enablePassthroughResponse.json();
+    assert(enablePassthroughResponse.status === 200, `启用 SSE 直通模式失败: ${enablePassthroughResponse.status}`);
+    assert(enablePassthroughPayload?.config?.stream_action === "passthrough", "当前配置未切换到 SSE 直通模式");
+
+    const passthroughThreadId = "thread_sse_passthrough";
+    const passthroughRetryKey = reasoningRetryKeyForRequest("/responses", {
+      stream: true,
+      thread_id: passthroughThreadId,
+      test_reasoning_retry_key: "sse-passthrough",
+    });
+    const passthroughStream = await readSseUntilClose(
+      `http://127.0.0.1:${gatewayPort}/responses`,
+      {
+        stream: true,
+        thread_id: passthroughThreadId,
+        test_reasoning_before_success_times: 1,
+        test_reasoning_retry_key: "sse-passthrough",
+        test_stream_include_lifecycle: true,
+        test_stream_lifecycle_marker: "passthrough-raw-marker",
+        test_stream_delta_chunks: 2,
+        test_stream_chunk_delay_ms: 2,
+      },
+    );
+    assert(passthroughStream.status === 200, `SSE 直通状态异常: ${passthroughStream.status}`);
+    assert(passthroughStream.headers.get("x-upstream-reasoning-attempt") === "1", "SSE 直通不应发起 reasoning 重试");
+    assert(passthroughStream.text.includes("passthrough-raw-marker"), "SSE 直通不应改写上游生命周期 payload");
+    assert(passthroughStream.text.includes('"reasoning_tokens":516'), "SSE 直通不应拦截匹配的 reasoning 响应");
+    const passthroughRetryStats = upstream.getReasoningRetryStat(passthroughRetryKey);
+    assert(passthroughRetryStats.totalRequests === 1, "SSE 直通不应启动多轮 reasoning 请求");
+    const passthroughRequestsResponse = await fetch(
+      `http://127.0.0.1:${gatewayPort}/__codex_retry_gateway/api/requests?query=${encodeURIComponent(passthroughThreadId)}`,
+      { headers: adminHeaders },
+    );
+    const passthroughRequestsPayload = await passthroughRequestsResponse.json();
+    const passthroughEntry = (passthroughRequestsPayload?.entries || []).find(
+      (entry) => entry.thread_id === passthroughThreadId,
+    );
+    assert(passthroughEntry?.inspected === false, "SSE 直通请求不应标记为已检查");
+    assert(passthroughEntry?.reasoning_retry_stop_reason === "stream_passthrough", "SSE 直通请求未记录跳过重试原因");
+    assert((passthroughEntry?.stream_chunk_count || 0) >= 1, "SSE 直通请求未累计流式 chunk");
+
+    const restoreStrictStreamResponse = await fetch(`http://127.0.0.1:${gatewayPort}/__codex_retry_gateway/api/config`, {
+      method: "POST",
+      headers: { ...adminHeaders, "content-type": "application/json" },
+      body: JSON.stringify({ stream_action: "strict_502" }),
+    });
+    assert(restoreStrictStreamResponse.status === 200, "测试后恢复严格 SSE 模式失败");
+
     const capturedLifecycleStream = await readSseUntilClose(
       `http://127.0.0.1:${gatewayPort}/responses`,
       {