UiPath LangChain Client [langchain-v1.19.0]

[1.19.0] - 2026-09-09

Added

• UiPathBaseChatModel now surfaces the LLM Gateway's per-request dollar cost as response_metadata["associated_dollar_cost"] when the caller opted in by sending X-UiPath-LlmGateway-IncludeAssociatedDollarCost: true (e.g. via default_headers) on a passthrough model. invoke() / ainvoke() set it on the result message. stream() / astream() (and invoke() routed through streaming) yield one extra empty chunk carrying it after the vendor's last chunk, since the gateway only reports the cost after the terminal event; merging the chunks folds it into response_metadata. Covers all passthrough chat models, including the Bedrock ones: the gateway's trailing costMetadata event is decoded by the core client and hidden from langchain-aws. Opted-in Gemini streams additionally log langchain-google-genai's "Gemini produced an empty response" warning for the gateway's trailing frame; the cost is still surfaced. The key is absent when the gateway did not price the call — absence means "not priced", never $0.

Changed

• Requires uipath-llm-client>=1.19.0.