When using WebSockets, that's the lifetime of the WebSocket.
But when using the HTTP batch transport, a session is a single HTTP request, that performs a batch of calls all at once.
So there's actually no need to hold state across multiple HTTP requests or connections, at least as far as Cap'n Web is concerned.
This does imply that you shouldn't design a protocol where it would be catastrophic if the session suddenly disconnected in the middle and you lost all your capabilities. It should be possible to reconnect and reconstruct them.
When using WebSockets, that's the lifetime of the WebSocket.
But when using the HTTP batch transport, a session is a single HTTP request, that performs a batch of calls all at once.
So there's actually no need to hold state across multiple HTTP requests or connections, at least as far as Cap'n Web is concerned.
This does imply that you shouldn't design a protocol where it would be catastrophic if the session suddenly disconnected in the middle and you lost all your capabilities. It should be possible to reconnect and reconstruct them.