fix(message-placeholders): use plain text langchain format for placeh… #616
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…olders to resolve
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failing test works locally -> flakey? should eventually probably move to recordings |
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fixes langfuse/langfuse#9097
Important
ChatPromptClientnow uses a plain text format for unresolved placeholders compatible with LangChain, with updated tests to verify this behavior.ChatPromptClientinpromptClients.tsnow converts unresolved placeholders to a plain text format compatible with LangChain, avoiding direct dependency on LangChain.getLangchainPrompt()to return placeholders as tuples like["placeholder", "{name}"].prompts.e2e.test.tsto verify new placeholder format ingetLangchainPrompt().ChatPromptTemplate.fromMessages()for unresolved placeholders.This description was created by
for cf67c43. You can customize this summary. It will automatically update as commits are pushed.
Disclaimer: Experimental PR review
Greptile Summary
Updated On: 2025-09-16 14:27:48 UTC
This PR fixes the format of unresolved message placeholders when converting Langfuse chat prompts to LangChain format. The core change addresses compatibility issues between Langfuse's
getLangchainPrompt()method and LangChain'sChatPromptTemplate.fromMessages()functionality.What Changed:
The PR modifies how unresolved placeholders are represented in the LangChain format conversion. Previously, placeholders were returned as objects with
variableNameandoptionalproperties:Now they are returned as simple tuples matching LangChain's native format:
Integration with Codebase:
This change is part of the prompt management system in the
packages/client/src/prompt/promptClients.tsfile, specifically within theChatPromptClient.getLangchainPrompt()method. The fix ensures that when users call this method to get LangChain-compatible prompts, the output can be directly consumed by LangChain'sChatPromptTemplate.fromMessages()without requiring additional transformation logic.The change maintains Langfuse's independence from LangChain as a direct dependency while ensuring proper interoperability. The E2E tests were updated to reflect this new tuple format and include a new test case that verifies direct compatibility with
ChatPromptTemplate.fromMessages().PR Description Notes:
Confidence score: 4/5
Context used:
Rule - Open a GitHub issue or discussion first before submitting PRs to explain the rationale and necessity of the proposed changes, as required by the contributing guide. (link)