nix-flake-init

name	nix-flake-init
description	Establish or improve a minimal Nix flake and dev shell for a project. Use when creating new projects, adding reproducible tooling, configuring direnv, or standardizing development commands.

Nix Flake Init

Use this skill to add or improve Nix development environment support.

Workflow

1. Inspect the project before editing:
   • language/framework
   • existing flake.nix, shell.nix, .envrc, package.json, mix.exs, *.tf, lockfiles
   • documented setup/test commands
2. Prefer the smallest useful flake.
3. Prefer reproducible project-local tooling over global installs.
4. Include direnv integration only when appropriate; ask before replacing an existing .envrc.
5. Avoid large abstractions (flake-parts, devenv, custom overlays) unless the project already uses them or the user asks.
6. Provide verification commands.

Defaults

• Use nixpkgs unstable unless the repo has a pinned preference.
• Prefer pkgs.mkShell for simple projects.
• Add language tools needed for the project, not every possible tool.
• If adding npm/node tooling, use the Node version expected by the project when discoverable.
• If adding Elixir tooling, include appropriate elixir, erlang, and common build deps.
• For Terraform projects, include terraform, tflint, and format/check commands when useful.

Safety

Ask before:

• deleting or replacing existing Nix files
• adding a large framework
• changing lockfiles unrelated to the Nix change
• adding binary caches or substituters