How I structure a Next.js project so it doesn't rot

This site is the third Next.js project I've structured from scratch, and the first one I expect to maintain for years. The difference is a few decisions made early.

The structure that survived

src/
  app/        # routes only — thin, no business logic
  components/ # presentational pieces, data comes in as props
  content/    # the site's truth: projects, posts, identity — typed data
  lib/        # everything that isn't UI: SEO, markdown, helpers

The load-bearing decision is content/. Projects, blog posts, and identity live as typed data, not as JSX. Pages became functions of data, and updating the site means editing a record — not surgery on a component. Content and presentation stopped being entangled, and maintenance got cheap.

The rules that prevent rot

• routes render; they don't decide. Logic lives in lib, content lives in content, layout lives in components
• every folder answers a question: "where does X live?" should have one obvious answer
• types at the boundary: content modules export typed arrays, so a bad entry is a build error, not a broken page

The test

Six months from now, I should be able to change anything — a project status, a blog post, a colour — by touching one file. So far, the structure is holding. That's the whole goal.