dotfiles

My macOS environment for two Macs, declared in one Nix flake (nix-darwin + home-manager).

• Terminal: Ghostty + Herdr, one workspace per git worktree for Claude Code and Codex
• Editor: Neovim
• Packages: Nix

Shell for humans and AI agents

AI agents (Claude Code, Codex, ...) now run more commands in this shell than I do, so the shell is plain by default and human UX is opt-in.

• .zshenv defines is_human: true only when stdin/stdout are a TTY and no agent marker (CLAUDECODE, AI_AGENT, ...) is set
• Agents get plain zsh: none of the human aliases (cp -i, ls → eza), no fzf-driven cd, EDITOR=true and PAGER=cat, so nothing waits for input
• .zshrc returns early unless is_human; below that line come aliases, plugins, prompt, keybinds and setopts

Export AI_AGENT=1 to force the agent side.

One file, one lifecycle

What is added and removed together is installed and configured in one file under nix/home-manager/tools/ (or nix/hosts/<host>/ for one Mac), imported automatically: usually one tool, sometimes a tool with its companions or a set, like the Kubernetes tools below. Adding a tool is adding a file, and deleting the file is all it takes to remove it. Three properties make that safe:

• Cohesion: deleting a tool's file removes everything that was for it (package, aliases, variables, plugins), so nothing outlives the tool.
• Loose coupling: deleting a tool's file breaks nothing else. A tool used inside another's settings is referenced by its store path, not through PATH. In the example below, kubectx's picker keeps working after fzf.nix, and fzf on PATH with it, is deleted.
• Reproducibility: a new Mac gets the same thing. Everything is declared here and pinned by flake.lock; what Nix cannot hold (self-updating apps through Homebrew casks, Claude Code) is declared as an exception.

A tool's settings sit next to its package, by who they are for: my.human for humans only, my.ai for agents only, my.env for both. The rules are in AGENTS.md, and how Nix makes the properties hold is in docs/concepts/dependencies.md.

# nix/hosts/PC-M-2025-026/kubernetes.set.nix (abridged)
# A set: the Kubernetes tools, added and removed together with this file
{ lib, pkgs, ... }:
let
  # kubectx runs fzf for its picker, looking it up on PATH by name. This wraps
  # kubectx so it finds fzf by its path in the Nix store instead: deleting
  # fzf.nix takes fzf off PATH, but not away from kubectx.
  kubectx = pkgs.symlinkJoin {
    name = "kubectx-with-fzf";
    paths = [ pkgs.kubectx ];
    nativeBuildInputs = [ pkgs.makeWrapper ];
    postBuild = ''
      wrapProgram $out/bin/kubectx --suffix PATH : ${lib.makeBinPath [ pkgs.fzf ]}
    '';
  };
in
{
  # Installed by this file, and uninstalled when it is deleted
  home.packages = with pkgs; [
    helmfile
    kubectl
    kubectx # the wrapped one above
    kustomize
  ];

  # For humans only: agents never get this abbreviation
  my.human.plugins.zsh-abbr.init = ''
    abbr --session --quiet k=kubectl
  '';
}

Layout

flake.nix                # one configuration per Mac
nix/
  darwin.nix, macos.nix  # system settings and macOS System Settings for every Mac
  homebrew.nix           # vendor apps installed by Homebrew casks
  hosts/                 # per-Mac packages, casks and App Store apps
  home-manager/          # dotfile links, shell env, tool files in tools/
  ...
home/                    # hand-written dotfiles, linked into ~ under the same names
  .zshenv, .zshrc, .zsh/ # zsh
  .config/               # linked to ~/.config as a whole
  .claude/               # Claude Code user settings
  bin/                   # scripts still being shaped
  skills/                # my own Agent Skills on trial
  ...
docs/                    # guides, concepts and reference (see docs/README.md)

Apply changes

sudo darwin-rebuild switch --flake ~/src/github.com/babarot/dotfiles

Updating packages is in maintenance.md.

Docs

• Setting up a Mac
• Everything else (how things work, how to maintain them, why they are this way) is indexed in docs/