Handle synchronous requests to the LangGraph API.
Provides error messaging and content handling enhancements above the underlying httpx client, mirroring the interface of HttpClient but for sync usage.
Owns the sync shared SSE handle, subscription registry, and fan-out thread.
Synchronous thread-centric streaming surface for the v3 protocol.
SyncThreadStream is a synchronous context manager that owns a
SyncProtocolSseTransport for one thread, dispatches commands (run.start,
run.respond), exposes typed subscriptions over a single shared SSE,
surfaces lifecycle state (interrupted, interrupts) via an always-on
lifecycle watcher thread, and provides typed projections (thread.values,
thread.messages, thread.tool_calls, thread.extensions).
Sync mirror of libs/sdk-py/langgraph_sdk/_async/stream.py.