# NixOS AGENTS and style-skill scope design tree

This tree reviews `configs/nixos/AGENTS.md`.
It decides which instructions belong in Nix style rules.

## Known facts

- `configs/nixos/AGENTS.md` has 70 lines.
- Each frontier question quotes the complete instruction under review.
- This review decides instruction placement only.
- It supplies guidance for desktop, Firefox, Neovim, AI tooling, and NixOS gotchas.
- The `/review` prompt loads `nix-style` for Nix files.
- `nix-style` loads every rule under `src/skills/style/nix/rules/`.
- The current Nix rules cover Nix syntax and flake structure.
- `configs/nixos/AGENTS.md` includes a guest-module ownership rule.
- The RomM session missed that ownership rule during implementation.
- `registry.window-icon` exists in `configs/nixos/registry/window-icon.nix`.
- Desktop application modules declare window classes and rendered icons in that registry.
- Hyprland reads the registry to generate workspace icon mappings.
- The AGENTS instruction named the registry after its introduction on 2026-10-11.
- The `class` option describes its window-class match.
- The `icon` option describes a string icon value.
- The registry schema does not document the rendered-string requirement or the class-discovery command.
- Hyprland renders `config.registry.env` as its `env` configuration.
- The `env` registry replaced direct Hyprland environment declarations in commit `370cab8f8`.
- `configs/nixos/modules/desktop/apps/r2modman.nix` enables a graphical application without a `registry.window-icon` declaration.
- The current registry modules already validate value uniqueness and field combinations.
- They do not validate required producer declarations.
- The registry collector is specific to the NixOS dotfiles configuration.
- A non-discoverable environment fact records local behavior that configuration, source code, and normal tool help do not reveal.
- The current instruction groups are:
  - Desktop: window icons, Hyprland environment variables, and cursor settings.
  - Firefox: search-engine declarations and extension-storage compatibility.
  - Neovim: Nixvim package-set selection.
  - AI tooling: Herdr key names and Pi configuration locations.
  - Gotchas: registry APIs, guest boundaries, SOPS ownership, guest mounts, deployment, DNS, hardware, module paths, and host commands.

## Decision tree

- Instruction review
  - Settled: Review each complete instruction in source order.
  - Registry conventions
    - Settled: Create `src/skills/style/nix/rules/dotfiles.md`.
    - Graphical application icon instruction
      - Settled: Move the complete instruction to `src/skills/style/nix/rules/dotfiles.md`.
    - Hyprland session environment instruction
      - Settled: Remove it because `registry.env` superseded it.
    - Firefox search-engine instruction
      - Settled: Remove it because the Firefox module documents the configuration.
    - Firefox extension-storage instruction
      - Settled: Move it to a comment above `extensions.settings` in `modules/desktop/apps/firefox.nix`.
    - Neovim package-set instruction
      - Settled: Move it to a comment above `nixpkgs.useGlobalPackages` in `modules/shell/nvim/default.nix`.
    - Herdr key-name instruction
      - Settled: Remove it.
    - Pi extension location instruction
      - Settled: Remove it. It recorded a completed migration from NixOS-managed sources.
    - Pi generated-settings instruction
      - Settled: Remove it because the Pi module documents the managed boundary.
    - Library-function qualification instruction
      - Settled: Generalize it and move it to `src/skills/style/nix/rules/general.md`.
    - Guest ownership instruction
      - Settled: Move it to `src/skills/style/nix/rules/dotfiles.md`.
    - SOPS guest-owner instruction
      - Settled: Move it to `src/skills/style/nix/rules/dotfiles.md`.
    - Nested guest-mount instruction
      - Settled: Remove it because the example describes no active layout.
    - `deploy-to` instruction
      - Settled: Remove it. Agents cannot complete its remote sudo steps.
    - Pikachu deploy-closure instruction
      - Settled: Remove it because `deploy-to` encodes the required import path.
    - Public-DNS instruction
      - Settled: Remove it.
    - Hardware-configuration instruction
      - Settled: Remove it because the root auto-generated-file rule owns the policy.
    - Chaotic-cache instruction
      - Settled: Remove it because `modules.host.cachyos.enable` owns the cache configuration.
    - Module-relative-path instruction
      - Settled: Remove it because Nix evaluation reports invalid paths.
    - Pikachu `uptime` instruction
      - Settled: Remove it because the command exposes its supported options.
    - Guest-ACME-evaluation instruction
      - Settled: Remove it because current direct guest evaluation succeeds.
    - systemd executable instruction
      - Settled: Remove it because `general.md` already requires `lib.getExe'` for non-main executables.

## Frontier

The frontier is empty.

## Shared understanding

Remove these instructions from `configs/nixos/AGENTS.md`:

- Hyprland session environment
- Firefox search engines
- Herdr shifted punctuation
- Pi extension source location
- Pi managed settings
- Nested guest mounts
- `deploy-to` behavior
- Pikachu deploy closures
- Public DNS boundary
- Hardware configuration
- Chaotic cache selection
- Module-relative paths
- Pikachu boot time
- Guest ACME evaluation
- systemd executable selection

Move these instructions intact to `src/skills/style/nix/rules/dotfiles.md`:

- Graphical application icons
- Guest ownership
- SOPS guest ownership

Move the generalized library-function qualification convention to
`src/skills/style/nix/rules/general.md`.

Move these instructions to code comments:

- Firefox extension storage: above `extensions.settings` in
  `configs/nixos/modules/desktop/apps/firefox.nix`
- Nixvim package set: above `nixpkgs.useGlobalPackages` in
  `configs/nixos/modules/shell/nvim/default.nix`

The review does not decide how to restore the auto-generated status of
`configs/nixos/hosts/pikachu/hardware-configuration.nix`.

The operator confirmed this design and authorized the edits.