I've started looking into this. It's pretty straight forward adding filters to be able to alter the dropdown action menus, but I got stuck onto two issues:

• When running the handler we'd like to show some kind of loading indicator.
• When the handler is done the view should be reloaded to see the result of the actions (when marking a comment as spam in the comments list, the comments list should be updated).

The first issue may not be a big deal, even though it will impair the UX. But the second issue must be handled in some way to solve this.

What about adding a trigger function to the plugin client API? The API could look like:

triggerAction('video-watch.comment-list.reload');
triggerAction('loading-indicator.load-start');
triggerAction('loading-indicator.load-end');

The triggerAction API may be useful in other cases as well. Any thoughts, @Chocobozzz ?

Ping @Chocobozzz

Sorry for the late feedback! Seems like a good idea. Do you have an example of other plugin systems that use such a method to ask for the core client to perform actions?

Unfortunately not

Wordpress has something similar.

function example_callback( $arg1, $arg2 ) {
    // (maybe) do something with the args.
}
add_action( 'example_action', 'example_callback', 10, 2 );

/*
 * Trigger the actions by calling the 'example_callback()' function
 * that's hooked onto `example_action` above.
 *
 * - 'example_action' is the action hook.
 * - $arg1 and $arg2 are the additional arguments passed to the callback.
do_action( 'example_action', $arg1, $arg2 )

https://developer.wordpress.org/reference/functions/do_action/

In our case it can be translated to:

video-comments.component.ts

  ngOnInit () {
    addAction('video-watch.comment-list.reload', this.resetVideo)
    ...
  }

  ngOnDestroy () {
    removeAction('video-watch.comment-list.reload')
    ...
  }

plugin.js

const onClickSpamButton = () => {
  deleteComment()
  doAction('video-watch.comment-list.reload')
}

Seems interesting, plugins would also be able to add actions. I agree with the design!