ClientConfig

API key for authentication.

• If a string is provided, that key will be used
• If undefined (default), the key will be auto-loaded from environment variables (LANGGRAPH_API_KEY, LANGSMITH_API_KEY, or LANGCHAIN_API_KEY)
• If null, no API key will be set (skips auto-loading)

Base URL of the LangGraph API server.

Defaults to http://localhost:8123, unless the runtime provides a langgraph_api:url global override.

Options forwarded to the internal AsyncCaller, such as retry, concurrency, or custom fetch behavior.

Headers applied to every request.

The configured API key, when present, is added as the x-api-key header after these defaults are initialized.

Hook for inspecting or mutating a request before it is sent.

Receives the resolved URL and prepared RequestInit; return the original init or a replacement object to continue the request.

Streaming protocol used by stream-capable endpoints.

Defaults to "legacy" for backwards compatibility.

Default timeout, in milliseconds, applied to client requests.

Per-request timeoutMs values override this default. Passing null at the request level disables the configured timeout for that request.