nix-darwin System Configuration Manager

Assists with managing a declarative macOS system configuration built with Nix Flakes and nix-darwin. Handles system rebuilds, package updates, profile switching, and configuration changes.

What This Skill Does

This skill helps you work with a nix-darwin + Home Manager configuration that declaratively manages macOS system settings, applications, and dotfiles. It supports dual profiles (personal/work), handles system rebuilds, manages flake updates, and guides configuration modifications.

Instructions

1. Understanding the Configuration Structure

Before making changes, familiarize yourself with the architecture:

- `common.nix` — Shared development tools (neovim, git, tmux)

- `personal.nix` — Personal applications (Discord, Blender, Obsidian)

- `work.nix` — Work-specific tools (1Password, EAS CLI)

- `homebrew.nix` — Homebrew packages and casks

- `dock.nix` — macOS dock configuration

- `karabiner.nix` — Keyboard remapping

- `git.nix` — Git configuration with work/personal email switching

- `ghostty.nix` — Terminal emulator settings

- `zsh.nix` — Shell configuration

2. Rebuilding the System

After making configuration changes, rebuild the system:

**For personal profile:**

```bash

sudo /Users/john/.config/nix/rebuild-and-switch.sh

or use the alias:

darwin-rebuild-switch

```

**For work profile:**

```bash

sudo /Users/john/.config/nix/rebuild-and-switch-work.sh

or use the alias:

darwin-rebuild-switch-work

```

3. Updating Packages

To update all flake inputs (package versions):

```bash

nix flake update

or use the alias:

flake-update

```

This updates `flake.lock` with the latest package versions from nixpkgs and other inputs.

4. Cleaning Up Old Generations

Remove old system generations (older than 7 days):

```bash

sudo nix-collect-garbage --delete-older-than 7d

or use the alias:

darwin-cleanup

```

5. Making Configuration Changes

When modifying the system:

1. **Identify the correct file** based on what you want to change:

- System-wide settings → `configuration.nix`

- User dotfiles/programs → `home.nix` or `home-manager/*.nix`

- Applications → `apps/common.nix`, `apps/personal.nix`, or `apps/work.nix`

- macOS-specific settings → `macos/*.nix`

2. **Edit the file** using your preferred editor

3. **Test the changes** by rebuilding:

```bash

darwin-rebuild-switch # or -work variant

```

4. **Verify** the changes took effect

5. **If dotfiles changed**, remember that Home Manager creates symlinks from `/dotfiles/`, so edits to those files require a rebuild to activate

6. Common Development Aliases

The configuration includes these Git aliases (defined in `configuration.nix`):

7. Key System Features

**Development environment includes:**

**Configuration management:**

8. Troubleshooting

**If rebuild fails:**

**If dotfile changes don't appear:**

Examples

**Example 1: Add a new application to the personal profile**

User: "Add Visual Studio Code to my personal applications"