Nix Flake

Every repository an agent works in should have a flake.nix. It gives you — and any human or agent that comes after you — a one-command, reproducible toolchain: nix develop drops into a shell with the project's compiler, package manager, and linters, independent of whatever happens to be installed on the host.

This skill covers two things: noticing when a repo is missing its flake.nix, and writing a good one. The template below is the official default since August 2026 (NixOS/templates#103), explained in depth by Nixcademy.

Checking for a flake

When you start working in a Git repository, check whether a flake.nix already exists at the repo root: