nix-rebuild - SKILL.md Agent Skill

name: nix-rebuild description: > Rebuild nix-darwin/NixOS system after dotfiles changes. Use when config files managed by Nix (lazygit, ghostty, etc.) need to be regenerated, or after editing any .nix file in the dotfiles repo.

Nix System Rebuild

After changing any Nix-managed config in ~/.config/dotfiles, the system must be rebuilt for changes to take effect. Nix store symlinks are read-only — you cannot edit them in place.

Quick Rebuild

cd ~/.config/dotfiles
sudo darwin-rebuild switch --flake .

darwin-rebuild has a NOPASSWD sudoers rule, so this works non-interactively.

Using hey

The hey command wraps rebuilds:

hey rebuild    # or: hey re
hey test       # build + activate without boot entry
hey rollback   # roll back to previous generation

When to Rebuild

After editing any .nix file
After editing config files symlinked through home-manager (lazygit, ghostty, etc.)
When you see "permission denied" writing to a Nix store path

Workflow

Edit source config in ~/.config/dotfiles/
Commit changes
Run sudo darwin-rebuild switch --flake ~/.config/dotfiles
Verify the symlink now points to updated Nix store path