Merge pull request #19554 from getsentry/fix/langchain-handlechainstart-runname

fix(langchain): use runName argument in handleChainStart to fix unknown_chain spans

Author: priscilawebdev

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

@@ -184,8 +184,17 @@ export function createLangChainCallbackHandler(options: LangChainOptions = {}):
     },
 
     // Chain Start Handler
-    handleChainStart(chain: { name?: string }, inputs: Record<string, unknown>, runId: string, _parentRunId?: string) {
-      const chainName = chain.name || 'unknown_chain';
+    handleChainStart(
+      chain: { name?: string },
+      inputs: Record<string, unknown>,
+      runId: string,
+      _parentRunId?: string,
+      _tags?: string[],
+      _metadata?: Record<string, unknown>,
+      _runType?: string,
+      runName?: string,
+    ) {
+      const chainName = runName || chain.name || 'unknown_chain';
       const attributes: Record<string, SpanAttributeValue> = {
         [SEMANTIC_ATTRIBUTE_SENTRY_ORIGIN]: 'auto.ai.langchain',
         'langchain.chain.name': chainName,