fixup! fix(tracing): add gen_ai.request.messages.original_length attributes (#18608)

Author: isaacs

packages/core/src/tracing/openai/index.ts

@@ -117,20 +117,14 @@ function addResponseAttributes(span: Span, result: unknown, recordOutputs?: bool
 
 // Extract and record AI request inputs, if present. This is intentionally separate from response attributes.
 function addRequestAttributes(span: Span, params: Record<string, unknown>): void {
-  if ('messages' in params) {
-    const truncatedMessages = getTruncatedJsonString(params.messages);
-    span.setAttributes({
-      [GEN_AI_REQUEST_MESSAGES_ATTRIBUTE]: truncatedMessages,
-      [GEN_AI_REQUEST_MESSAGES_ORIGINAL_LENGTH_ATTRIBUTE]: undefined,
-    });
-    if (Array.isArray(params.messages)) {
-      span.setAttribute(GEN_AI_REQUEST_MESSAGES_ORIGINAL_LENGTH_ATTRIBUTE, params.messages.length);
-    }
-  } else if ('input' in params) {
-    const truncatedInput = getTruncatedJsonString(params.input);
+  const src = 'input' in params ? params.input : 'messages' in params ? params.messages : undefined;
+  // typically an array, but can be other types. skip if an empty array.
+  const length = Array.isArray(src) ? src.length : undefined;
+  if (src && length !== 0) {
+    const truncatedInput = getTruncatedJsonString(src);
     span.setAttribute(GEN_AI_REQUEST_MESSAGES_ATTRIBUTE, truncatedInput);
-    if (Array.isArray(params.input)) {
-      span.setAttribute(GEN_AI_REQUEST_MESSAGES_ORIGINAL_LENGTH_ATTRIBUTE, params.input.length);
+    if (length) {
+      span.setAttribute(GEN_AI_REQUEST_MESSAGES_ORIGINAL_LENGTH_ATTRIBUTE, length);
     }
   }
 }