What’s a good pattern for mixing bulk-able actions and single actions?

I'm working on a web frontend for an existing API. We currently have a table that looks like this:

You can perform various one-time actions on items. At the moment, every action you can take on an item requires you to select the item, then go to "Item actions" and click on the action you want to take. This is because of technical constraints that don't allow us to perform actions in bulk.

We want to add a new action. This action can either be applied to a single item (like the other actions) or the entire list of items, but not to an arbitrary subset of items.

What's a good way I can communicate this to the user?

Edit: The reason I didn't immediately go for checkboxes is that the bulk action can only be applied to the entire list, not to a subset of it. Selecting 2 items out of 4 doesn't make sense, and allowing the user to do so would be a waste of their time. I've edited the question to make this clearer.