Borrowing it
Nothing to install: this file belongs to ahonn/dotfiles. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/ahonn/dotfiles/master/.claude/skills/nix-darwin/SKILL.mdgit clone --depth 1 https://github.com/ahonn/dotfilesWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/ahonn/dotfiles/nix-darwin)<a href="https://agentmods.dev/skills/ahonn/dotfiles/nix-darwin"><img src="https://agentmods.dev/badge/skills/ahonn/dotfiles/nix-darwin/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/ahonn/dotfiles/nix-darwin"><img src="https://agentmods.dev/badge/skills/ahonn/dotfiles/nix-darwin.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 2 findings, up to medium
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- medium Privilege Escalation · line 73 Commands invoke sudo or root privileges. Verify this elevated access is necessary and justified.Fix: Avoid sudo/root unless strictly required. Prefer least-privilege patterns. If elevation is needed, document the justification and scope.
- medium Privilege Escalation · line 74 Commands invoke sudo or root privileges. Verify this elevated access is necessary and justified.Fix: Avoid sudo/root unless strictly required. Prefer least-privilege patterns. If elevation is needed, document the justification and scope.
What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00031 | $0.00580 |
| Opus 5.5 | $0.00012 | $0.00232 |
| Sonnet 5.5 | $0.00006 | $0.00116 |
| Haiku 4.5 | $0.00003 | $0.00058 |
Grade A, and why
nix-darwin scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 35 lines — stays where its author put it; the contents beside it link to each section on GitHub.
nix-darwin Configuration
Two hosts (workstation, homelab) are built by mkDarwinConfig in flake.nix from three layers: darwin modules (system) → home-manager (user) → nix-homebrew (GUI apps and taps). Both hosts share nixpkgs-unstable. Read the host's home.nix and homebrew.nix for what is currently enabled; do not rely on remembered program lists.
Conventions
New programs follow templates/program-module.md: an options.my.<program>.enable module under modules/home-manager/programs/, imported by the host's home.nix and enabled there. Shared programs are imported by modules/home-manager/base.nix instead.
| Config delivery | When to use | Example |
|---|---|---|
mkOutOfStoreSymlink |
Config edited often, applied without rebuild | neovim, aerospace |
builtins.readFile |
Config copied into the Nix store | zed-editor |
Inline Nix settings |
Small, Nix-native config | ghostty, starship |
Naming: kebab-case.nix files and host names, my.<program>.enable options, symlink/<name>.symlink dotfiles, and conventional commit scopes such as feat(neovim): or fix(darwin):.
Read by problem
| Problem or decision | Reference |
|---|---|
| Where a module is wired in, or why the layout is shaped this way | architecture.md |
| Build, rollback, generations, input updates, garbage collection | commands.md |
darwin-rebuild or evaluation failure, Homebrew DSL or tap errors, macOS compatibility |
gotchas.md |
| The user asks how to restructure or improve the configuration | community-patterns.md — check each pattern's status in this repo first |
Complete the change
Evaluate each affected host with nix eval --raw .#darwinConfigurations.<host>.system.drvPath. nix flake check only checks formatting and passes even when a host fails to evaluate; nix fmt fixes formatting. Changes under modules/, hosts/, or flake.nix take effect only after darwin-rebuild switch; follow the project CLAUDE.md for when that needs confirmation.
What ships with it
5 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 1mo ago Changed · -81 lines · -36 tokens per session scan B → A e260af61155e
- 1mo ago First seen · 116 lines · 67 tokens per session scan B a42e5b11c955
nix-darwin is a skill published in the GitHub repository ahonn/dotfiles (63 stars, last pushed 6d ago), licensed MIT. It adds 31 tokens to every session and 580 once invoked, about $0.0001 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.
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