fix: pace captured SSE replay

scripts/test-gateway-e2e.mjs

@@ -303,6 +303,7 @@ function startFakeUpstream(port, options = {}) {
             ? parsed.test_stream_delta_chunks
             : 1;
           const deltaTextBase = parsed.test_stream_delta_text || "hello";
+          const outputItemId = "msg_stream";
           const lifecyclePayloadExtra = parsed.test_stream_lifecycle_marker
             ? {
               marker: parsed.test_stream_lifecycle_marker,
@@ -329,17 +330,46 @@ function startFakeUpstream(port, options = {}) {
                   output: lifecyclePayloadExtra,
                 },
               })}\n\n`,
+              `data: ${JSON.stringify({
+                type: "response.output_item.added",
+                output_index: 0,
+                item: {
+                  id: outputItemId,
+                  type: "message",
+                  status: "in_progress",
+                  role: "assistant",
+                  content: [],
+                },
+              })}\n\n`,
             ]
             : [];
-          const streamChunks = Array.from({ length: deltaChunkCount }, (_, index) => {
+          const deltaTexts = Array.from({ length: deltaChunkCount }, (_, index) => {
             const deltaText = deltaChunkCount === 1 ? deltaTextBase : `${deltaTextBase}-${index + 1}`;
-            return `data: ${JSON.stringify({ type: "response.output_text.delta", delta: deltaText, response_id: "resp_stream", thread_id: parsed.thread_id || "thread_stream", retry_attempt: reasoningAttempt })}\n\n`;
+            return deltaText;
+          });
+          const streamChunks = deltaTexts.map((deltaText) => {
+            return `data: ${JSON.stringify({ type: "response.output_text.delta", item_id: outputItemId, output_index: 0, content_index: 0, delta: deltaText, response_id: "resp_stream", thread_id: parsed.thread_id || "thread_stream", retry_attempt: reasoningAttempt })}\n\n`;
           });
           if (parsed.test_stream_include_lifecycle) {
             streamChunks.unshift(...lifecycleChunks);
           }
           if (parsed.test_stream_include_lifecycle) {
             streamChunks.push(
+              `data: ${JSON.stringify({
+                type: "response.output_item.done",
+                output_index: 0,
+                item: {
+                  id: outputItemId,
+                  type: "message",
+                  status: "completed",
+                  role: "assistant",
+                  content: [{
+                    type: "output_text",
+                    text: deltaTexts.join(""),
+                    annotations: [],
+                  }],
+                },
+              })}\n\n`,
               `data: ${JSON.stringify({
                 type: "response.completed",
                 response: {
@@ -552,7 +582,8 @@ async function readSseUntilClose(url, requestBody) {
     }
   }
 
-  text += decoder.decode();
+  text += decoder.decode();
+  const elapsedMs = Date.now() - startedAt;
   return {
     status: response.status,
     headers: response.headers,
@@ -560,6 +591,7 @@ async function readSseUntilClose(url, requestBody) {
     closedByError,
     readCount,
     firstChunkDelayMs,
+    elapsedMs,
   };
 }
 
@@ -1650,6 +1682,11 @@ async function run() {
     );
     assert(capturedLifecycleStream.status === 200, `/responses 捕获回放状态异常: ${capturedLifecycleStream.status}`);
     assert(capturedLifecycleStream.readCount > 1, "/responses 捕获回放不应退化为单块响应");
+    const observedReplayDurationMs = capturedLifecycleStream.elapsedMs - capturedLifecycleStream.firstChunkDelayMs;
+    assert(
+      observedReplayDurationMs >= 250,
+      `/responses 捕获回放缺少真实传输间隔: ${observedReplayDurationMs}ms`,
+    );
     const capturedEvents = parseSseEvents(capturedLifecycleStream.text);
     const firstReplayEvent = capturedEvents.find((event) => event.payload);
     assert(
@@ -1680,11 +1717,32 @@ async function run() {
       capturedDeltas.every((delta, index) => delta === `captured-chunk-${index + 1}`),
       "/responses 捕获回放的长流 delta 顺序不完整",
     );
+    const outputItemAddedIndex = capturedEvents.findIndex(
+      (event) => event.payload?.type === "response.output_item.added",
+    );
+    const outputItemDoneIndex = capturedEvents.findIndex(
+      (event) => event.payload?.type === "response.output_item.done",
+    );
+    const firstDeltaIndex = capturedEvents.findIndex(
+      (event) => event.payload?.type === "response.output_text.delta",
+    );
     const completedIndex = capturedEvents.findIndex((event) => event.payload?.type === "response.completed");
     const lastDeltaIndex = capturedEvents
       .map((event) => event.payload?.type)
       .lastIndexOf("response.output_text.delta");
-    assert(completedIndex > lastDeltaIndex, "/responses 捕获回放未在所有 delta 后终止");
+    assert(
+      outputItemAddedIndex >= 0 && outputItemAddedIndex < firstDeltaIndex,
+      "/responses 捕获回放未在 delta 前保留 output_item.added",
+    );
+    assert(
+      outputItemDoneIndex > lastDeltaIndex && completedIndex > outputItemDoneIndex,
+      "/responses 捕获回放未按 delta、output_item.done、response.completed 顺序终止",
+    );
+    const completedOutputItem = capturedEvents[outputItemDoneIndex]?.payload?.item;
+    assert(
+      completedOutputItem?.content?.[0]?.text === capturedDeltas.join(""),
+      "/responses 捕获回放的 output_item.done 与全部 delta 内容不一致",
+    );
     assert(!capturedLifecycleStream.text.includes("captured-lifecycle-marker"), "/responses lifecycle 归一化仍透传了巨大的生命周期原始 payload");
 
     const normalizedLifecycleStream = await readSseUntilClose(