PieFed v1.4 (to be released very soon) will have emoji reactions on posts and comments. An emoji reaction can be a unicode character like 😍 or a colon-delineated string like :piefed: which gets automatically converted into an image when the post/comment is displayed.
Setting a reaction uses the same API endpoint as casting a vote (and behind the scenes reactions are federated as Likes, for Lemmy compatibility) but with an emoji element added to the JSON payload.
Also when looking at a post or comment in the API there is an emoji_reactions element that can be used to get a summary of the reactions that have happened so far. Compare https://crust.piefed.social/api/alpha/comment?id=456791 with https://crust.piefed.social/post/84566#comment_456791 to see what I mean.
Do a GET on /api/v3/site to retrieve a list of all the custom emoji (the ones with :something:) that this instance knows about and to find what images to convert usages of them in emoji_reactions to.
If you do add it to work like that, you'd need to make it abundantly clear that a thumbs-down is a downvote. Or people will accidently downvote without meaning to.
I don't think it should work like that. It'd be a good way to express disapproval without downvoting, which is desirably used for spam/off-topic/hateful content (as it is mostly used on the fediverse).
Except that reactions count as upvotes, so I don't think it'd actually be a good way to express disapproval without downvoting.
Upvotes aren't really controversial though. One assumes if you give a thumbs up or a :100: that it counts as an upvote in itself, which is fine. But many other reacts may have more abstract uses.
I would prefer it not downvote. I don’t downvote content but i’ll give someone a thumbsdown if they’re being a turd.
Yeah, i think it would be even more confusing if certain emojis counted as downvotes.