ai-agents-langchain-prompt-pla-when-using-getlangchainprompt-without-providing-al-9430a4af

THEN Manually map unresolved placeholder objects by converting { variableName, optional } to { type: 'placeholder', name: variableName } before passing to Langchain, or upgrade to Langfuse JS/TS SDK v4.2.0+ where the issue is fixed. Example: const fixedMessages = rawMessages.map(msg => msg.variableName ? { type: 'placeholder', name: msg.variableName } : msg);

const rawMessages = langfusePrompt.getLangchainPrompt();
const fixedMessages = rawMessages.map(msg => {
  if (msg.variableName && typeof msg.optional === 'boolean') {
    return { type: 'placeholder', name: msg.variableName };
  }
  return msg;
});
const langchainPrompt = ChatPromptTemplate.fromMessages(fixedMessages);