chimney flashing repair
https://astro-wiki.win/index.php/Why_Roof_Leak_Tracing_Is_the_First_Step_to_a_Permanent_Fix
We noticed a small stain on the ceiling near the fireplace and figured the chimney flashing might be loose. After the last storm, a bit of water must have found its way in behind the lead or copper seal where it meets the roof. Pulled out the ladder and the caulk gun, cleaned the old brittle tar out, then laid down fresh flashing cement and a new layer of metal that wraps tight around the brick. The repair held through the next rain and the ceiling dried out nicely.