[Feature] Browser-side ActorSystem with Web Workers

[pathosDev]

Size / Priority

• Size: M

Rationale

Frontend state-machines (Redux, XState, Zustand) all reinvent actor patterns. actor-ts in the browser:

• Off-thread compute (Web Workers).
• Type-safe message passing.
• Backpressure via Worker IPC.
• Bridge to server cluster via WebSocket → use the same actor protocol.

Real win: one actor model for frontend + backend, with messages crossing the wire transparently.

Design sketch

// actor-ts/browser subpackage

// Spawn an actor in a Web Worker:
const system = createBrowserActorSystem();
const worker = system.actorOfWorker(import.meta.url, props);

// Bridge to server cluster:
const bridge = system.connectToCluster('wss://api.example.com/cluster');
const serverActor = await bridge.actorAt('/user/services/orders');
await serverActor.ask(new GetOrder('42'));

Implementation:

• Web Worker per dispatcher.
• MessageChannel for IPC between Workers + main thread.
• WebSocket for server-cluster bridge.
• Shared types via TypeScript project references.

Integration

• Actor: same core; Worker is just a different mailbox-dispatcher.
• RemoteActorRef: WebSocket-based remote.
• Cluster bridge: same WireMessage format.

Out of scope / non-goals

• Multi-Worker clustering — too much complexity.
• SharedArrayBuffer — out of scope.

Open design questions

1. Worker per actor vs Worker per dispatcher: dispatcher (lower overhead).
2. Serialisation: structuredClone for IPC; JSON/CBOR for WS.
3. Bundle size: minimal core only.

Test plan

1. Spawn actor in Web Worker; message exchange works.
2. Cross-Worker tell.
3. Bridge to server → ask server actor.
4. Browser app reactive to server events.
5. Bundle size ≤ 50KB.

Acceptance criteria

• actor-ts/browser subpackage.
• Web Worker dispatch + IPC.
• WebSocket cluster bridge.
• Sample app.
• Documentation.
• CHANGELOG entry.

Pre-implementation checklist

• Coordinate with [Feature] WASM/Edge-runtime subpackage (Cloudflare Workers / Deno Deploy) #209 (edge — similar build pipeline).
• WebSocket protocol decided.