A few months ago Zambs messaged me about a good way to automate year tags based on site IDs, and I've finally gotten round to it.
With the info they gave and looking into it more I've found that:
Twitter/X uses a snowflake for their IDs which include the time and date they were posted for anything past Nov 2010, you can convert it to Unix Epoch with:
(Tweet ID / 2 ** 22) + 1288834974657
Discord does the same since the start of 2015, converted with this code:
(Discord ID >> 22) + 1420070400000
FurAffinity has the timestamp in their image URLs, plus the post IDs are sequential, so I can find the first and last post ID for each year and use that as well.
Inkbunny also uses sequential IDs, so can do the same as FA just without the timestamp.
The idea is that if an image doesn't already have a year tag then check if it has any of those sources, if it does then check them all for the earliest time, then if the E6 post wasn't created before that year, add the year tag.
Of course I'd keep a log of what posts it changes so I can undo things if needed, and I'd be able to test it offline with the DB Exports first.
Given most uploads are from either FA or Twitter/X I thought it'd be a pretty good way to do it, and was hoping for some feedback before actually implementing it in case I've missed something or there's other sites I could add to the list.