Adding a new transport

ShareGo uses the ILocalTransport interface to abstract the network layer. This allows swapping WebSocket for WebRTC (or anything else) without changing crypto, protocol, or session logic.

Steps

1. •

   Create a new file in core/src/transport/ (e.g. webrtc-transport.ts)

2. •

   Implement ILocalTransport from core/src/transport/types.ts:

import type { ILocalTransport, TransportState, TransportStateCallback, MessageCallback } from "./types.js";

export class WebRTCTransport implements ILocalTransport {
  async listen(port: number): Promise<void> { /* ... */ }
  async connect(addr: string): Promise<void> { /* ... */ }
  send(data: Uint8Array): void { /* ... */ }
  onMessage(cb: MessageCallback): void { /* ... */ }
  offMessage(cb: MessageCallback): void { /* ... */ }
  onStateChange(cb: TransportStateCallback): void { /* ... */ }
  offStateChange(cb: TransportStateCallback): void { /* ... */ }
  close(): void { /* ... */ }
  getState(): TransportState { /* ... */ }
  getLocalAddress(): string | null { /* ... */ }
}

1. •

   Key requirements:

   • •listen() = receiver role (wait for incoming connection)
   • •connect() = sender role (connect to receiver)
   • •Only one peer per transport (2-user session limit)
   • •Reject additional connections after the first peer
   • •Fire onStateChange callbacks on every state transition
   • •send() must throw if no peer is connected
   • •close() must release all resources
2. •

   Export from core/src/transport/index.ts

3. •

   Test by wiring it into a Session and running the handshake

4. •

   Platform adapters — if the transport requires platform-specific code (e.g. native sockets), create adapters in each app shell that implement the same interface:

   • •Desktop: apps/desktop-tauri/src/adapters/
   • •Mobile: apps/mobile-rn/src/adapters/
5. •

   Update docs — add the new transport to docs/ARCHITECTURE.md (tech stack section) and mention any security implications in docs/THREAT_MODEL.md

Checklist

• • Implements all ILocalTransport methods (including offMessage and offStateChange)
• • Rejects second peer connection
• • Fires state callbacks: idle -> listening/connected -> disconnected -> closed
• • send() throws when no peer connected
• • close() releases all resources
• • offMessage() and offStateChange() properly unregister callbacks
• • Exported from transport barrel (core/src/transport/index.ts)
• • Works on all target platforms for this transport type
• • Platform adapters created for desktop and mobile (if needed)
• • Unit tests covering connection, messaging, disconnection, and rejection
• • docs/ARCHITECTURE.md updated
• • docs/THREAT_MODEL.md updated if security surface changes