dotfiles/.claude/tasks/0001-skeleton-and-building-host.md

spec

spec
laptop-mvi

What to build

Stand up the Skeleton and a minimal neogaia Host that evaluates and whose system toplevel builds — the walking skeleton every later slice extends and re-verifies against.

The Skeleton is a hand-rolled flake (no flake-parts): nixos-unstable base channel, an unstable overlay exposing nixpkgs-unstable as unstable.<name>, a stable overlay exposing nixos-26.05 as stable.<name>, and chaotic-nyx wired as an input with its overlay and binary cache. The helper lib is trimmed to three pieces: the Auto-loader (recursively discovers and imports every Module under modules/ and every Host under hosts/ with no null-placeholder traversal hack), the host-builder, and the script-from-file helper. with lib.my is not used — dependencies are inherited explicitly. The Enable convention uses the stdlib enable-option helper; every Module is imported unconditionally and guards its body with mkIf config.modules.<path>.enable. home-manager is sourced from nix-community (master, nixpkgs followed) and integrated as a NixOS module with global packages and user packages. The user is an explicit option defaulting to alexion (no impure environment lookup), placed in wheel, driving the system user and the home-manager user in lockstep. The neogaia Host carries only enough (placeholder hardware-configuration.nix, filesystems/bootloader stubs, stateVersion) to make nixosConfigurations.neogaia.config.system.build.toplevel evaluate and build; real disk/kernel/networking arrive in later slices.

Design the per-Host layout so disk layout, kernel, and channel are all per-Host concerns from the start (story 20), so the desktop and servers extend this foundation without restructuring.

Acceptance criteria

• nix flake check succeeds and the flake exposes nixosConfigurations.neogaia.
• nixosConfigurations.neogaia.config.system.build.toplevel builds.
• Adding a new .nix file under modules/ is auto-discovered and imported without editing any imports list, and stays inert until its enable flag is set.
• All three overlays resolve: unstable.<pkg>, stable.<pkg>, and a chaotic-nyx package are each reachable in a Host.
• home-manager builds as part of the same nixos-rebuild switch toplevel (system + user environment atomic).
• The user option defaults to alexion, has no impure environment lookup, places the user in wheel, and drives both the system and home-manager user.
• The old nixosModules flake output and the with lib.my idiom are absent.

Implementation Notes

• Verification. nix flake check builds checks.x86_64-linux.neogaia = the Host toplevel (the spec's primary seam). Overlays confirmed via nix eval of pkgs.unstable.hello (2.12.3), pkgs.stable.hello (2.12.1), and pkgs.linuxPackages_cachyos.kernel (7.1.3, from chaotic). Auto-loader inertness confirmed both ways: the reference modules/example.nix is off by default, and extendModules with modules.example.enable = true activates its body.
• chaotic binary cache. Wired via inputs.chaotic.nixosModules.default, which puts both the nyx-cache.chaotic.cx substituter and its trusted public key into the built config (verified by evaluating config.nix.settings.substituters/trusted-public-keys). chaotic deliberately does not follow our nixpkgs, so the cache stays usable. Making the substituter/key explicit is task 0003's concern; here it is inherited from the module.
• Shared base lives in system/. The Skeleton's shared base config (overlays, user, flakes, home-manager wiring) is a system/ module always imported by the host-builder, kept separate from the auto-loaded feature Modules under modules/ so the base is never gated by an enable flag.
• modules/example.nix kept intentionally. It is the Auto-loader / Enable-convention reference every real Module copies; remove it once a real Module supersedes its teaching value.
• scriptFromFile present but unused. The task mandates the helper lib carry it ("the script-from-file helper"); its first caller lands with a later Module.
• Home-manager base user only. The base sets home.username/homeDirectory/stateVersion for the user; extraSpecialArgs passes both inputs and my (the flake lib) so upcoming HM Modules (fish/tmux/nvim) can reach scriptFromFile.
• Deviations from plan. Added an options.user.description (GECOS) alongside user.name — small and expected for a real account. Baseline git + global allowUnfree are set in the base (git is required for flakes; unfree is needed by chaotic/home-manager and later Claude Code). Placeholder fileSystems/bootloader and hardware-configuration.nix in neogaia are stubs that task 0002 (disko) replaces.