Richer bot interactions

Suggestion
As a developer of assorted multiplatform amusement and utility bots, I find Matrix's plaintext interactions to be somewhat lacking, especially in compraison to how richly formatted the messages themselves can be.

Some grokking around for "button" "drop down" etc. didn't really indicate that anyone else had requested richer interactions, so I guess I will.

There are two main components to what I need for richer bot interactions that I'm not getting out of Matrix:

• the ability for a user to send something to another user (bot) in the context of a room that does not necessarily form a visible message in the room (through e.g. buttons, dropdowns, inline keyboards, whatever features you want to take from other platforms)
• the ability for the bot to send feedback in response to this interaction that again may not necessarily form a visible message in the room (e.g. through an ephemeral message or a popup/snackbar/whatever you want to call it)

The underlying thing (I think) needed for both of these is the ability to dispatch events that are only visible to a user and another user within a room. Everything else would just be building on top of that base thing.

Begin by reviewing the Matrix specification's current event and room-interaction model, then read the two existing comments for constraints and prior discussion. Done would require a settled protocol design for user-scoped interactions and bot feedback, including how these differ from visible room messages.