@source-repo/rpc

The library: classes as contracts over socket.io and MQTT 5, with the machinery a plant needs and a browser tolerates.

npm install @source-repo/rpc

• Command semantics — query, idempotent-command, non-repeatable-command declared on the contract; graded execution defaults, a bounded mailbox, conflation for setpoint-shaped commands, and a durable idempotency hook.
• Observable components — RpcComponent<Props, State> with cached snapshots, epoch/revision ordering, per-channel initializing | live | stale | closed, and a store that plugs into useSyncExternalStore.
• Command authority — $acquire/$release, the plant's arbitration concept: granted, visible in every snapshot, always expiring, with only declared methods ever gated.
• Topology — every host answers for its components' parent and owner with durable epochs, CAS mutations, and an owner fence on calls ($with({ ownerEpoch })).
• Structural context — defineRpcContext tokens resolved through one declared axis, across hosts, with atomic remounts and bounded, explicit capture.
• Security — per-connection authentication, per-frame signing (HMAC or Ed25519), authorize() on every call and subscription, TLS with a plant's own CA.
• A worker can be a peer, not only a host — MessagePortTransport carries the same flat frame over a MessagePort: posted rather than encoded, so nothing parses and the boundary is still real. Symmetric, because a channel has two ends and no broker; presence is an announcement each way and a peerGone when the port closes; carrying lets the host advertise the rest of the network so the worker can call out to it.
• One rule for what may cross a boundary — RpcValue checks a value against what every placement carries rather than what the nearest one happens to accept, so a class instance, a cycle or a shared buffer is refused with its path named instead of arriving flattened, or crossing a thread and failing at a host. The narrowest boundary decides, which is what keeps placement unobservable.
• A worker-hosted component is still a component — the worker owns the logic and the private state; the supervisor owns identity, authority and the last published snapshot. The facade is a real RpcComponent, so the server exposes it, publishes its snapshots and gates its declared methods without knowing where the logic runs. While that logic is parked at a breakpoint, a console still reads the last snapshot it published.
• Logic can be hosted on its own thread — RpcWorkerHost runs one instance in a worker and hands back a forwarder the ordinary exposure takes, so the whole policy stack stays on the transport's thread and only the handler crosses. That is what makes a component stoppable mid-handler: a thread parked by Atomics.wait is parked outright, so a component that shares a thread with its socket cannot be paused without pausing the socket.

Full documentation: the guide and the CHANGELOG. On npm: @source-repo/rpc.