next-dev-loop

The edit/verify rhythm during next dev — make a change, then confirm it actually works at runtime, not only that the types or the build are happy.

You verify through two views of the same running app:

• /_next/mcp — an HTTP endpoint Next.js exposes about itself. Knows framework-specific things: routes, segments, RSC, server actions, server logs, and errors as Next.js saw them. Call tools/list for the current surface.
• agent-browser — a CLI that drives a real Chrome. Knows framework-agnostic browser things: DOM, console, network, React fiber, vitals. Before driving it, run agent-browser skills get core once for the version-matched usage guide — don't guess subcommands from memory.

The two views cross-check each other.