ADR 0092 — Realtime contracts may bind an existing transport

Context

Applications may already own one Socket.IO client for authentication, reconnection and durable subscriptions. createRealtimeClient previously made adopting Stitchkit validation require a second connection or a wholesale lifecycle migration.

Decision

bindRealtimeClient(contract, transport) accepts the smallest structural transport used by the canonical validated client: connection state, event subscription, emit, Promise acknowledgement and connection-change observation. It returns BoundRealtimeClient, which exposes validated event and request operations but no connect or disconnect methods.

createRealtimeClient constructs the official Socket.IO adapter, delegates all validation and request behavior to the same binder, then adds lifecycle methods because it owns that transport. Binding validates required capabilities immediately. It neither imports Socket.IO eagerly nor creates, connects or closes a socket.

Consequences

• Existing subscriptions and reconnect policy remain application-owned.
• Created and bound clients cannot drift in payload, acknowledgement, timeout or disconnect semantics.
• Lifecycle ownership is visible in the return type rather than documentation alone.