fix: pace captured SSE replay

gateway.mjs

@@ -4079,7 +4079,7 @@ function cloneResponseHeaders(sourceHeaders) {
   return headers;
 }
 
-const CAPTURED_STREAM_REPLAY_CHUNKS_PER_TICK = 1;
+const CAPTURED_STREAM_REPLAY_DELAY_MS = 5;
 
 function cloneBufferList(chunks) {
   if (!Array.isArray(chunks) || chunks.length === 0) {
@@ -4091,13 +4091,16 @@ function cloneBufferList(chunks) {
 }
 
 async function writeBufferedStreamChunks(res, chunks) {
-  let writesSinceYield = 0;
-  for (const chunk of chunks || []) {
-    if (!chunk || chunk.length === 0 || res.destroyed || res.writableEnded) {
-      continue;
+  const replayChunks = (chunks || []).filter((chunk) => chunk && chunk.length > 0);
+  res.socket?.setNoDelay(true);
+  res.flushHeaders?.();
+
+  for (let index = 0; index < replayChunks.length; index += 1) {
+    if (res.destroyed || res.writableEnded) {
+      break;
     }
+    const chunk = replayChunks[index];
     const accepted = res.write(chunk);
-    writesSinceYield += 1;
     if (!accepted) {
       await new Promise((resolve) => {
         let settled = false;
@@ -4117,12 +4120,13 @@ async function writeBufferedStreamChunks(res, chunks) {
         res.once("close", onClose);
         res.once("error", onClose);
       });
-      writesSinceYield = 0;
-      continue;
     }
-    if (writesSinceYield >= CAPTURED_STREAM_REPLAY_CHUNKS_PER_TICK) {
-      writesSinceYield = 0;
-      await new Promise((resolve) => setImmediate(resolve));
+    if (
+      index < replayChunks.length - 1 &&
+      !res.destroyed &&
+      !res.writableEnded
+    ) {
+      await sleep(CAPTURED_STREAM_REPLAY_DELAY_MS);
     }
   }
 }