Chat: cannot wait for changes in a file if file for today hasn't been created yet

The long chat system only creates a file for chat in a given day if someone actually sends a message. After it is created, each user of the chat subscribes to web socket events when the file changes.
Anyone opening the chat before the file for today has been created gets an error because it hasn't got a 200 response from the file and so can't look at the headers in that.

But in fact the 404 response does have a Updates-Via: wss://example.com header.

So it needs the rdflib function which looks at the headers at it to also look at 404 responses.
And it needs the server to allow one to watch for a non existent file being created.

Comienza localizando el manejo del archivo de chat largo y la función de rdflib que lee el encabezado Updates-Via. Rastrea cómo se manejan las respuestas 404 y las suscripciones websocket, y luego verifica la ruta del servidor para observar un archivo que todavía no existe. Se considera terminado cuando un chat abierto antes de que exista el archivo de hoy puede esperar a que se cree sin producir un error.