Defining client callback type in WIT

I'm trying to define a component interface in WIT format so that components (client) can pass callbacks (closures) to host. Host can then store the callback somewhere and then invoke the callback when certain event happens.

I'm a bit confuse how can I describe this using WIT format. I'm thinking of something like this:

package foo:bar

world client {
  resource callback {
    // Invokes the callback
    call: func()
  }
  
  // Passes the callback from client to host
  import register-callback: func(callback: callback)
  
  // The main function for the client
  export main: func()
}

But because I didn't export the resource (I can't do export callback apparently), I guess this is treated as if callback is implemented by the host, which is not I want. I can change it to:

package foo:bar

interface host {
  use callback-types.{callback}

  register-callback: func(callback: callback)
}

interface callback-types {
  resource callback {
    call: func()
  }
}

interface client {
  use callback-types.{callback}
  run: func()
}

world client-world {
  import host
  export client
}

But then, will host/callback and client/callback be treated as the same type?

The issue’s two WIT examples are the concrete entry points; start by tracing how resources are declared, imported, exported, and shared across the shown world. Read the discussion and relevant component-model specification material to determine whether the host and client callback types are identical and what supported design applies; done means an unambiguous answer or updated WIT guidance.