StreamControllerOptions

LangGraph SDK client used to send requests and receive responses.

Optional fetch override, forwarded to the SSE transport. Useful for auth proxies, Next.js route handlers, or tests with injected mocks. Ignored when webSocketFactory is also supplied.

Initial values to display immediately when loading a thread. Useful for displaying cached thread data while official history loads. These values will be replaced when official thread data is fetched.

Note: UI components from initialValues will render immediately if they're predefined in LoadExternalComponent's components prop, providing instant cached UI display without server fetches.

Specify the key within the state that contains messages. Defaults to "messages".

Callback that is called when a new stream is created.

Callback that is called when the thread ID is updated (ie when a new thread is created).

Thread ID this transport is bound to.

How this thread talks to the agent server. Accepts either a built-in transport string or a custom AgentServerAdapter:

• "sse": HTTP commands + one SSE event stream per subscription.
• "websocket": single bidirectional WebSocket.
• an AgentServerAdapter: custom transport that replaces the built-in factories entirely. fetch / webSocketFactory are ignored in this mode.

Defaults to the client-level streamProtocol ("v2-websocket" → "websocket", otherwise "sse").

Optional WebSocket factory. Supplying it flips the adapter into WebSocket mode — SSE is bypassed entirely.