Perform handshake with the proxy. Returns handshake info on success.

Receive one frame from the proxy. Returns Some frame for a normal Frame message. Also returns Some a synthetic terminal frame when the proxy delivers its standalone Shutdown envelope: the synthetic frame has FrameNumber = 0u and carries a single GameEvent.Shutdown event. Callers that need the last real game-frame number must rewrite the sentinel before dispatching. A clean socket close without a Shutdown envelope raises from the underlying read. See ../HighBarV2/specs/030-proxy-contract-docs/contracts/shutdown-wire-shape.md for the upstream wire-shape contract.

When false, sendCallback silently drops events from interleaved Frame messages (the pre-031 behaviour). When true, interleaved frames are stashed in a per-stream replay buffer and drained by the next receiveFrame on the same stream. Default false. Set to true by BarClient.Start() after warmup + unit-def loading completes so mid-game callback round-trips preserve engine events.

Send a callback request and wait for the response.

Send a frame response with commands.