Add per-adapter architecture docs in event-targets/ directory

- Create docs/architecture/event-targets/ with individual specs:
  in-process, redis, websocket-client, websocket-server,
  worker, iroh-spoke, iroh-hub
- Update event-targets.md to serve as index with topology model
  (symmetric vs fan-out) and adapter status table
- Update architecture.md index to reference new directory

docs/architecture/event-targets/websocket-client.md

@@ -0,0 +1,73 @@
+---
+status: draft
+last_updated: 2026-05-07
+---
+
+# WebSocket Client Event Target
+
+**Import**: `@alkdev/pubsub/event-target-websocket-client`
+**Peer dep**: none (WebSocket is a web standard)
+**Status**: Not yet implemented.
+
+Wraps a single `WebSocket` connection for the client (spoke) side. Bidirectional — can both send and receive events.
+
+## `createWebSocketClientEventTarget`
+
+```ts
+function createWebSocketClientEventTarget<TEvent extends TypedEvent>(
+  ws: WebSocket,
+): TypedEventTarget<TEvent>;
+```
+
+Takes an already-connected `WebSocket`. The caller is responsible for connection lifecycle (including reconnection — see below).
+
+## Protocol
+
+WebSocket provides native message boundaries (no length-prefix needed). Each message is a JSON-serialized `EventEnvelope`:
+
+```json
+{ "type": "call.responded", "id": "uuid-123", "payload": { "output": 42 } }
+```
+
+### Sending (dispatchEvent)
+
+```ts
+dispatchEvent(event) {
+  this.ws.send(JSON.stringify(event.detail));
+  // event.detail is the EventEnvelope { type, id, payload }
+  return true;
+}
+```
+
+### Receiving (addEventListener)
+
+```ts
+ws.onmessage = (msg) => {
+  const envelope = JSON.parse(msg.data);
+  const topic = `${envelope.type}:${envelope.id}`;
+  const event = new CustomEvent(topic, { detail: envelope });
+  // dispatch to local listeners
+};
+```
+
+## Key Properties
+
+- **Bidirectional** — `dispatchEvent` sends over WS, `addEventListener` receives from WS
+- **Per-connection** — one event target per WebSocket connection
+- **JSON framing** — WebSocket provides native message boundaries
+- **No native deps** — works in browsers and Node
+- **Envelope serialization** — sends/receives the full `EventEnvelope` JSON
+
+## Reconnection
+
+WebSocket connections drop. On reconnect, the spoke must create a new `WebSocket` and a new `WebSocketClientEventTarget`. Reconnection logic belongs to the spoke lifecycle, not the event target.
+
+The event target itself is per-connection. A new connection means a new instance.
+
+## Test Plan
+
+1. **Send path** — dispatchEvent serializes envelope and calls ws.send
+2. **Receive path** — ws.onmessage parses envelope, creates CustomEvent, dispatches to listeners
+3. **Topic scoping** — type:id topics correctly formed from envelope
+4. **Connection close** — ws.onclose propagates to listeners (error event?)
+5. **Multiple listeners** — multiple addEventListener on same topic