Reconnecting to same fly instance using `fly-force-instance-id`

Is it possible to retrieve the instance id from a response, so that I can use it to reconnect to the same instance using fly-force-instance-id? I don’t care where the first request (of a stateful protocol) ends up, but I need to send the next requests to the same instance to ensure that the correct instance keeps track of the state.

Looking through the response headers, I only see server and fly-request-id, but neither of them seem to contain the id of the instance that sent the response.

Explicitly return env var FLY_ALLOC_ID in a http header, say x-myapp-src-fly-vm: <fly-alloc-id>, to the client?

Thanks, that’s a nice solution!