I have my own personal document (any text editor would do) for notes attached to whatever I'm working on. What's on it depends on the task but usually, I write

I have my own personal document (any text editor would do) for notes attached to whatever I'm working on. What's on it depends on the task but usually, I write down all the things that need to get done and the status of where I'm at. The notes I write aren't that specific to code though. Like, I'm not gonna write "I was looking at x file at code line y" but I'll write "Finishing serializer up" and any other notes that might help.