When I start a new project, I point to other ones where I'm happy with the quality as exemplars. I think its probably simpler to copy relevant stuff allow older projects go out of date until I start working on them again, then I tell the agent to look at the newer project to update its style.

I have 2-4 on going projects I tend to a bit of that, normally 2 at a time, when I pick up one of the others, I really just do that; point to the older one.

But within projects I don't really try to manage context, more so I just have an issue tracker which I add to keep track of stuff. In 2 of my long running projects I have some bootleg issue tracker built in (along with a screenshot QA tool which sends issues to the tracker) into the UI of the tool.

I guess to extent I can, I try to avoid keeping some preferences in the context like formatting and linting (including directory structure and white listing imports in certain parts). I've been trying to find more ways to automate that way, so I keep my prompts and skills and goals limited to objectives where possible, so preferences like styles and structure are automatically enforced.

When I have multiple agents, I just tell them to maintain write only ledgers to coordinate to avoid overlapping work, but it's easier when your project is broken up into self contained components with communication boundaries (defined in protobuf) like a FE/BE split or seperate service codebases (I reassemble it as a google style modular monolith to avoid running too many processes)