fix(langgraph): carry ToolMessage.error onto the LangChain status flag - #2263
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Both langgraph adapters dropped AG-UI's ToolMessage.error when converting an incoming tool message to a LangChain ToolMessage. LangChain has a status field (success/error) for this, and providers such as langchain_anthropic map it onto the model's tool-result flag. With the field dropped, a client-reported tool failure reached the model as a success. The impact is provider-dependent, so it was invisible on Gemini. Map error onto status in both adapters (TypeScript and Python): status is error when the AG-UI error field is set, else success. A test is added on each side. Scope: the status flag only. Preserving the error text and round-tripping it back to the client are separate questions raised in the issue and left out here. Fixes ag-ui-protocol#2226
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Fixes #2226.
Problem
Both langgraph adapters drop AG-UI's
ToolMessage.errorwhen they convert an incoming tool message to a LangChainToolMessage. LangChain has astatusfield ("success" | "error") for exactly this, and providers such aslangchain_anthropicmap it onto the model's tool-result flag. With the field dropped, a client-reported tool failure reaches the model as a success. The impact is provider-dependent, so it is invisible on Gemini and shows up on Anthropic.Fix
Map
errorontostatusin both adapters:"error"when the AG-UIerrorfield is set, else"success".integrations/langgraph/typescript/src/utils.ts, thetoolbranch ofaguiMessagesToLangChain. The langgraph-sdkToolMessagetype already typesstatus?: "error" | "success".integrations/langgraph/python/ag_ui_langgraph/utils.py, thetoolbranch ofagui_messages_to_langchain.The AG-UI
ToolMessageschema already haserrorin both languages, so no type changes are needed.Scope
This PR maps the flag only. The two open questions from the issue — preserving the
errortext and round-tripping it back to the client — look like a separate protocol topic and are left out here.Tests
A test is added on each side, next to the existing tool-message conversion tests.
message-conversion.test.ts— full package suite green, 265 tests.test_message_conversion.py—unittest discover testsgreen, 43 tests.