definitely a minimalist version of the idea of actions that we've talked about for farr for a long time but i keep putting off in search of a unified nice user interface approach.
This might be better discussed in a new topic but if you are referring to performing actions (such as email, rename, delete, zip, open with, copy, etc..) on search results then my vote would go to some kind of file type system similar to how explorer handles context menus for different file types. This way you could customize actions for different file extensions or perhaps even for different file type groups (docs, videos, music, etc..).
As far as how to integrate this into the UI i would advocate a system whereby after finding the object you want to perform the action on you would hit "tab" and that would then display all the matching actions for that file type in the results window. You could then begin typing the name of the action and have farr filter the action results until you have the one you want and you hit enter to execute that action.
For example, currently in farr if you hit tab on almost any object the full path of that object appears in the search box with pretty much the same info in the results box. Using the suggestion above hitting tab on the same file would instead put farr into say "action mode" which would display all the avail actions for that object in the results window. Some actions such as email, rename would obviously require more then one step. In these situations farr would need to track which objects and actions it was performing and build a kind of breadcrumbs of commands.
As for how to visually indicate to the user what is going on you could:
Use a breadcrumb system within the search box where you have the something like Test.txt > email, similar to how launchy does, with each arrow > representing a different action/command within "action mode" which is traversed using either the esc key to go back or the tab key to go onto the next action.
Another way would be to create an "info" display box right above (or inside) the search box with the breadcrumbs of pending actions similar to how an app called Dash does
Not sure how hard it would be to extract explorers context menu actions for each object type but that might be a good place to populate the action list. Im no expert but as far as i understand it windows stores all the actions for each object type in the registry with the name and command line needed to execute that action.
Taking the idea a little further you could also allow people to create and share action commands with a new section in the settings menu similar to how plugins are configured now. In this section you could also specify the order or default action for each file type as well as a hotkey for that action. This would be extremely cool because it would also allow people to create plugins for regular search results which is something i believe that current plugins cannot do.
While other methods such as action aliases work well I find that because you have to remember the exact name of each alias combined with the fact that they do not visually show the user what they do, unless there is a single result, make them a little difficult to use and hard to scale.
I really cant think of a more intuitive and user friendly way of adding actions to farr and while it might be a bit of change in how farr works it would be well worth it imho.