Yeah the biggest task these days that I do manually is curating the documentation. AGENTS.md in every major directory, and a variety of reference docs that are explicitly referenced in those files.

    # See DOC-ITEM-NAME

    DOC-ITEM-NAME.md
    When referencing documents, always use the exact syntax See <TAG> - this is enforced by a lint on precommit

Depending on language I've seen this scale past multiple millions of lines of code, as long as you pair it with all of the linting and tooling that you can possibly build.