pubsub/docs/architecture/event-targets/iroh-spoke.md

status, last_updated

status	last_updated
draft	2026-05-08

Iroh Spoke Event Target

Import: @alkdev/pubsub/event-target-iroh-spoke Peer dep: @alkdev/iroh (optional, NAPI-RS native addon — pending fork of iroh-ts) Status: Deferred. Pending fork of iroh-ts with Linux + WASM platform targets.

P2P QUIC event target for the spoke (client) side. The spoke initiates the connection and opens the bidirectional stream.

createIrohSpokeEventTarget

async function createIrohSpokeEventTarget<TEvent extends TypedEvent>(
  args: CreateIrohSpokeEventTargetArgs,
): Promise<TypedEventTarget<TEvent>>;

CreateIrohSpokeEventTargetArgs

Field	Type	Required	Description
endpoint	Endpoint	Yes	iroh endpoint (created with Endpoint.create())
hubNodeId	string | NodeId	Yes	The hub's public key (Ed25519)
alpn	string	No	Application-layer protocol. Default: "alkpubsub/1"

Protocol

Single bidirectional QUIC stream per connection. Length-prefixed JSON messages:

[4 bytes: length N][N bytes: JSON payload]

The JSON payload is the EventEnvelope:

{ "type": "call.responded", "id": "uuid-123", "payload": { "output": 42 } }

Connection Flow

1. Spoke creates Endpoint
2. Spoke calls endpoint.connect(hubNodeId, alpn) → Connection
3. Spoke calls connection.openBi() → SendStream + RecvStream
4. Spoke wraps streams in IrohSpokeEventTarget
5. On disconnect: RecvStream.readExact() throws, spoke must reconnect

Subscription Forwarding

Same pattern as WebSocket Client: when addEventListener is called for the first listener on a topic, the spoke sends a __subscribe control event to the hub. When removeEventListener removes the last listener for a topic, the spoke sends __unsubscribe. Reference counting ensures __subscribe is sent only on the first addEventListener for a topic, and __unsubscribe only when the last removeEventListener for that topic is called. This enables the hub's topic-based fan-out (see ADR-003).

Control events use the existing EventEnvelope format:

{ "type": "__subscribe", "id": "", "payload": { "topic": "message.sent:conv-123" } }
{ "type": "__unsubscribe", "id": "", "payload": { "topic": "message.sent:conv-123" } }

Key Properties

• NAT traversal — spoke dials hub by NodeId, no public IP needed
• Cryptographic identity — Connection.remoteNodeId() verifies the hub
• Bidirectional — dispatchEvent writes to SendStream, addEventListener reads from RecvStream
• Per-connection — one event target per QUIC connection
• Subscription forwarding — addEventListener/removeEventListener send __subscribe/__unsubscribe control events to the hub (see ADR-003)

R&D Needed

1. Fork of iroh-ts — @rayhanadev/iroh has one author and no tests. We plan to fork as @alkdev/iroh with Linux (NAPI-RS) + WASM platform targets. Windows and macOS native builds are deferred — cross-compilation from Linux is possible with NAPI but tricky, and macOS licensing is dubious for CI. Initial release: Linux native + WASM fallback. Adding other platforms is a future accessibility concern.
2. Stream multiplexing — multiple openBi() streams on one connection vs. single stream with multiplexed events. Single stream + JSON framing is simpler.
3. Reconnection — RecvStream.readExact() throws on connection close. Need to propagate this to listeners and support reconnect.

See ../iroh-transport.md for full protocol details, identity, and comparison with WebSocket.