Skip to main content
AWP has one unit of transmission: the channel. A session is a set of channels sharing one clock, one token, one sequence discipline, and one audit log. The protocol defines semantics per channel class; a binding decides how channels map onto connections.

​
Channel model

  • Every message belongs to exactly one channel. Channel 0 is the control channel, present in every session and carrying every JSON-RPC message; channels ≥ 1 are the observation and command channels declared in the manifest, assigned their channel_id in session.ready, and carried as frames. [AWP-TRN-005]
  • Classes. control: no loss, in order, replayed on resume by status_seq, audited in full. reliable: no loss, in seq order, resumed from a keyframe, audited by hash. latest-wins: droppable, newest wins, audited by hash. A channel’s class is fixed for the life of the manifest. [AWP-TRN-006]
  • Ordering. Order is guaranteed within a channel and never across channels; the only cross-channel relations are those the specification states explicitly — lockstep advance completion (AWP-TIM-003) and command-channel binding (AWP-CMD-003). [AWP-TRN-007]
  • Resumption. On session.resume the control channel replays per AWP-CTL-008; the agent re-establishes stream connections from the re-issued stream_endpoints; on every reliable channel the world’s first frame after resumption MUST be a keyframe carrying the resync flag, and the seq gap it reveals is not a loss (AWP-DAT-009); latest-wins channels continue unchanged. [AWP-TRN-008]

​
Bindings

  • The control channel is carried on one control connection per session (AWP-CTL-007); worlds MUST offer the WebSocket binding for it. Optional control bindings: stdio (local child processes) and gRPC. [AWP-TRN-001]
  • Bindings MUST preserve the order of every channel they carry. [AWP-TRN-002]
  • Channels ≥ 1 are carried either inline on the control connection or on stream connections negotiated in session.ready. A stream binding either gives every channel independent flow control or it does not: ws (WebSocket binary messages) no; grpc (HTTP/2 streams) no; webrtc (data channels) yes; webtransport (QUIC streams and datagrams) yes; shm (POSIX shared memory, local) yes. [AWP-TRN-003]
  • The inline binding — frames as obs.frame and cmd.frame notifications on the control channel (AWP-DAT-004) — is REQUIRED as the fallback when no other binding is mutually supported and is the default for lockstep sessions. [AWP-TRN-004]
  • Dependent streams. On a binding without independent flow control, including inline, a latest-wins channel cannot drop in transit, so the sender MUST hold at most one undelivered frame per such channel and replace it when a newer frame is produced; a channel that stalls MUST NOT delay the control channel or any other channel by more than that one frame. [AWP-TRN-009]
  • Stream reconnection. If a stream connection is lost while the control connection remains, the agent MAY reconnect to the same endpoint with the session token at any time and the world MUST accept it; grants are unaffected, reliable channels restart with a resync keyframe (AWP-DAT-009), and the world reports the outage on affected reliable channels through channel_degraded (AWP-SAF-009). [AWP-TRN-010]
  • Frame size. Each stream endpoint MAY declare max_frame_bytes (default 16 MiB); senders MUST NOT emit a larger frame on it, and a world MUST NOT assign a channel to an endpoint that cannot carry that channel’s largest declared frame. On webtransport, frames that exceed the datagram limit travel on a stream. [AWP-TRN-011]
AWP assumes the agent and the world share a network environment — the same machine or a trusted local network (an agent client in a browser tab beside a world simulator, a policy process beside a robot controller). Rendezvous across the public internet is out of scope; deployments that separate the two front the world with their own tunnel or proxy presenting a dialable endpoint.