fix: Override status for errors in anthropic streams

context: anthropic will always return a 200 status code, even when there
is actually an error sent in the event stream itself. this would confuse
customers as when looking at the logs in the Helicone dashboard,
they would expect to see a response since they see a 200 status code,
but instead would see some random JSON (the error). to fix this, we are
allowing the stream body parsers to override the status code.

Author: tomharmon

valhalla/jawn/src/lib/handlers/ResponseBodyHandler.ts

@@ -74,6 +74,10 @@ export class ResponseBodyHandler extends AbstractLogHandler {
 
     try {
       const processedResponseBody = await this.processBody(context);
+      if (processedResponseBody.data?.statusOverride) {
+        context.message.log.response.status =
+          processedResponseBody.data.statusOverride;
+      }
       context.processedLog.response.model = getModelFromResponse(
         processedResponseBody.data?.processedBody
       );

valhalla/jawn/src/lib/shared/bodyProcessors/IBodyProcessor.ts

@@ -11,6 +11,12 @@ export interface ParseInput {
 export type ParseOutput = {
   processedBody: any;
   usage?: Usage;
+  // Enables us to override successful status codes if an error
+  // occurs mid stream. Eg, Anthropic will always return a 200 for streams,
+  // but may send an error in the `data` event stream, in which case we want
+  // to override this so that the logs show up as an "error" in our Helicone
+  // dashboard.
+  statusOverride?: number;
 };
 
 export interface IBodyProcessor {

valhalla/jawn/src/lib/shared/bodyProcessors/anthropicStreamBodyProcessor.ts

@@ -47,6 +47,12 @@ export class AnthropicStreamBodyProcessor implements IBodyProcessor {
 
       try {
         const data = JSON.parse(line.replace("data:", "").trim());
+        if ("error" in data) {
+          return ok({
+            processedBody: data,
+            statusOverride: 500,
+          });
+        }
 
         // Handle input_json_delta for tool_use
         if (