This is a solution for the timeout issue when casting Home Assistant using CATT.

1. It is recommended to install this with HACS by adding a custom repository (important: select "Lovelace" as category). Alternatively, download ha-catt-fix.js and put it inside /config/www/.

2. Add it as a resource to your Home Assistant UI. Follow the instructions displayed by HACS. If you are not installing with HACS, then:

   If you use the YAML mode, put the following in your configuration.yaml:

   lovelace:
     mode: yaml
     resources:
       - url: /local/ha-catt-fix.js
         type: module
   

   Otherwise go to Settings -> Dashboards -> (three dots in the upper right corner) -> Resources.

3. In case of the YAML mode, a restart of Home Assistant is required.

That's it. Continue to use CATT for casting HA to your display but dismantle anything you had set up to re-cast it every 10 minutes.

The reason for the timeout is that nothing is being played so the receiver application gets closed. The solution for that is to add a hidden Cast media player component and play an image every 9 minutes. That is not new, it has been used in the official Home Assistant Cast integration for quite a long time.

However, there's one problem with DashCast (which is used by CATT to cast websites). It replaces itself with the target website (window.location = url). It means it looses control of the display. That's why this solution is to embed the receiver code into the Home Assistant UI itself and do the dummy playback there.