I created a capacitor plugin that enables to watch notifications being posted or removed. Read the documentation on GitHub.

Unfortunately, the plugin does not support running in the background. This is a conscious design choice, so that you are able to choose or implement your preferred method of “running in the background” yourself. The plugin capacitor-persistent-notification could help you with such an endeavor.

Install the plugin using:

npm i capacitor-notificationlistener
npx cap sync

And register it using add(NotificationListenerPlugin.class) in your MainActivity.java like in the following example:

// ... code ...
import ch.asinz.capacitornotificationlistener.NotificationListenerPlugin;
// ... code ...
    this.init(savedInstanceState, new ArrayList<Class<? extends Plugin>>() {{
      // Put it here!
      add(NotificationListenerPlugin.class);
    }});
// ... code ...

Please visit the documentation for further information.