fix: retry Codex overload error codes

gateway.mjs

@@ -4403,6 +4403,47 @@ function truncateRetryableMessage(value, maxLength = 280) {
   return text.length > maxLength ? `${text.slice(0, maxLength - 3)}...` : text;
 }
 
+const RETRYABLE_OVERLOAD_ERROR_CODES = new Set([
+  "server_is_overloaded",
+  "slow_down",
+]);
+
+function findRetryableOverloadErrorCode(value, state = { seen: new Set() }, depth = 0) {
+  if (!value || typeof value !== "object" || depth > 6 || state.seen.has(value)) {
+    return null;
+  }
+  state.seen.add(value);
+
+  if (Array.isArray(value)) {
+    for (const item of value) {
+      const match = findRetryableOverloadErrorCode(item, state, depth + 1);
+      if (match) {
+        return match;
+      }
+    }
+    return null;
+  }
+
+  const code = typeof value.code === "string" ? value.code.trim().toLowerCase() : "";
+  if (RETRYABLE_OVERLOAD_ERROR_CODES.has(code)) {
+    return {
+      matched_code: code,
+      matched_pattern: `error_code:${code}`,
+      matched_message: truncateRetryableMessage(
+        firstNonEmptyString(value.message, value.detail, value.description, code),
+      ),
+    };
+  }
+
+  for (const nested of Object.values(value)) {
+    const match = findRetryableOverloadErrorCode(nested, state, depth + 1);
+    if (match) {
+      return match;
+    }
+  }
+  return null;
+}
+
 function findRetryableUpstreamErrorMatch(config, upstreamStatusCode, parsedBody, bodyText) {
   const retryableMessages = normalizePhraseList(
     config.retryable_error_messages,
@@ -4420,10 +4461,16 @@ function findRetryableUpstreamErrorMatch(config, upstreamStatusCode, parsedBody,
     retryableStatusCodes.length === 0 ||
     retryableStatusCodes.includes(upstreamStatusCode)
   );
-  if (!statusEligible && !isRetryableErrorPayloadShape(parsedBody)) {
+  const failurePayload = isRetryableErrorPayloadShape(parsedBody);
+  if (!statusEligible && !failurePayload) {
     return null;
   }
 
+  const overloadCodeMatch = findRetryableOverloadErrorCode(parsedBody);
+  if (overloadCodeMatch) {
+    return overloadCodeMatch;
+  }
+
   return matchRetryableMessage(config, parsedBody, bodyText);
 }
 
@@ -4525,6 +4572,10 @@ function findRetryableStreamErrorMatch(config, parsedBody, bodyText, eventName =
   if (!isRetryableErrorPayloadShape(parsedBody, eventName)) {
     return null;
   }
+  const overloadCodeMatch = findRetryableOverloadErrorCode(parsedBody);
+  if (overloadCodeMatch) {
+    return overloadCodeMatch;
+  }
   return matchRetryableMessage(config, parsedBody, bodyText);
 }