Support tapback messages in mesh_interface.py

[afourney]

I am building an application (APRS <-> Meshtastic gateway), that would significantly benefit from being able to send tabpback messages. For example, a tabpback message of thumbs up could signal that an APRS message was acknowledged on the other side of the gateway. For this I understand that I need to supply a replyId and emoji.

Unfortunately mesh_interface.py only supports sending text messages. I would value either a tabpack method, or sample code for how I can create and send my own via data/protobuf.

[ianmcorvidae]

The tapback messages are just text messages under the hood, but it does appear there's a couple properties it would be useful to be able to set without needing to use very low-level functions.

It appears that the iOS code (the only codebase that supports any sort of "tapbacks" -- neither android nor web has such a concept) sets the emoji property on https://buf.build/meshtastic/protobufs/docs/main:meshtastic#meshtastic.Data to 1 (which seems to confusingly be a bool very inefficiently stored in a 4-byte fixed32), and also sets the reply_id field of the same to a message that is being replied to. The combination of the two seems to be what iOS considers when deciding what to display as a tapback.

You could send this today with the python library by constructing a Data protobuf with those fields set, setting it as the decoded field of a MeshPacket (and setting other fields as needed, particularly the payload and portnum fields on Data, and the channel on MeshPacket if needed), then passing that to the _sendPacket function on the interface (along with other relevant arguments, if desired).

I'll look into adding helpers for these fields though, since ideally the underscore-prefixed methods wouldn't need to be used by end users.

[afourney]

Thanks, I will give this a try!