Lemme just say first I want to apologize because I know there’s a very similar thread out there and I tried to look but couldn’t find it again.
Anyway, I’ve been frequently teaching new assistant techs as an engineer and I always like to sprinkle in past job experiences for purposes of roleplay, education, and immersion. For example I’ll usually say something like “Once, I was teaching a new tech but before we even got to the solars she was jumped by syndicate assassins. She never got to place her first wire…” I can see how this one could break the shield because it explicitly references syndies and traitors that we have no reason, as fresh employees who’s memories only began at round start, to know that syndicate assassins are a thing that might jump us. However I also feel that since this is not me saying “you should watch out for traitors in maints,” but instead telling a sad tale from my (character’s) past, it might be allowed.
Another thing I like to say, particularly on Bagel, is something to the effect of “Up here’s old Atmosia, when I find places like this I like to fix them up and turn them into my own little hangout spots.” Again, this is me explicitly referencing actions my character has taken in previous rounds, but I feel like it’s an in character statement of “when I find tucked away corners like this I try to make them my home” and not “I like to fix up this area of the map Bagel station once in a while.”
Other things I say are pieces of history and trivia like “I once got all the way out to solars without my insuls, bad time that.” and “Good few of my tours on other stations ended early due to singulo sabotage, but unless someone intentionally breaks the field it should be fine.” In particular the sabotage one is, again, directly saying “you should watch out for sabotage” which, with nothing to be suspicious about at round start, is a bit of a metashield breach to my understanding, but I’m wondering if the in-character nature of the statement and the idea of it being from past tours/shifts on other stations is enough to keep IC and maintain the shield.
Apologies for the long post, I wanted to provide a wealth of examples to get a more specific idea of what kind of past-event references are okay and which ones aren’t.