The operator's SSH client key existed only as a file created by hand on one
laptop, so a reimage would destroy it and lock the operator out of the remote.
It now lives in neogaia's own secrets file, encrypted to the admin identity and
neogaia alone, and the client is pointed at the decrypted path rather than a
copy in the user's home.
Access becomes a policy over roles instead of a per-host list of keys. A new
fleet declaration names each machine's role and client public key, and every
machine derives what it authorizes from that: a workstation admits workstations
alone, a server admits both, so a compromised server reaches no machine of the
operator's own. Registering a machine is an entry in that one file.
Only neogaia exists, so the server half of the policy is built rather than
exercised. Two assertions reject a machine missing from the fleet and any entry
whose role no policy defines.
The procedure was built around a login password set by hand through
nixos-enter, a step that no longer exists now that the password arrives
as a decrypted secret. Rather than patch around it, revise the document:
the LUKS passphrase is named as the only hand-entered secret, and identity
provisioning moves ahead of first boot, since there is no fallback
credential to get in with if decryption fails.
Cover the three procedures the install alone did not: provisioning a
running host live, the editing workflow and what it needs the admin
identity for, and recovery from the live ISO.
Per-machine client identities, so a compromised machine surrenders only
its own key, plus a role-based rule for which machines may reach which.
Only neogaia exists, so the server half is recorded rather than exercised.
The host's SSH identity was generated by the daemon, so reimaging the
laptop would invalidate it and break `known_hosts` for every client that
had ever connected.
Add `secrets/neogaia.yaml`, the first per-host secrets file, encrypted to
the admin identity and `neogaia` alone so a compromised machine cannot
decrypt another's material. It holds both host private keys; the public
halves are committed in plaintext.
Clear `services.openssh.hostKeys` to stop generation and point `HostKey`
at the decrypted paths. These are ordinary secrets rather than the
pre-user ones the password uses, exercising the second decryption path.
Wire sops-nix into the shared base config as unconditional plumbing, with
a two-tier age identity model: an admin identity held outside the repo, and
a per-host identity generated on the machine and kept on its encrypted root.
Both `sshKeyPaths` defaults are cleared so the SSH host keys stay out of the
decryption path and remain free to become secrets in their own right.
The primary user's password hash moves into a shared secrets file encrypted
to admin plus neogaia, consumed through `hashedPasswordFile` and decrypted
before accounts are created.
This needs `users.mutableUsers = false`: NixOS applies a declared hash to an
already-existing account only when that flag is false, so at the default the
hand-set password would have been kept and the change would have been inert.
Root consequently has no password and is locked; sudo from wheel is the way
in, and generation rollback remains the recovery path.
The detection file was written before the machine ran NixOS, as an educated
guess at what a Dell XPS 13 9380 needs, and said so. Its contents now come
from nixos-generate-config on the running machine.
The guess was wider than the measurement rather than narrower: it named
thunderbolt, usb_storage and sd_mod, none of which the scan reports, and
omitted rtsx_pci_sdmmc. Nothing needed to reach the root device was missing.
Filesystem, swap, LUKS and microcode declarations from the scan are dropped.
The disk layout derives the first three and the hardware profile supplies the
last, so carrying them here would duplicate definitions that are produced on
every evaluation.
Key sudo's credential cache per user rather than per terminal, holding it
for 60 minutes. An authentication made in the operator's own terminal then
covers commands issued by processes holding no terminal of their own, which
previously failed with a bare non-zero exit and no output.
No command is made passwordless. The password remains required; only the
cache holding it is shared, and any process running as the primary user can
spend that credential until it lapses.
A PreToolUse hook refuses a privileged command while the cache is cold,
naming the command that warms it, so the condition announces itself rather
than presenting as a stall. Both states were exercised against the running
system.
The reimage is done and verified on hardware: the boot partition is 2 GiB
and reports it, the hardware profile's kernel parameter and module blacklist
are live, and the encrypted root unlocks to a console login.
The install procedure ran without divergence, which is the reproducibility
evidence the task was after.
The reimage also wiped the hand-written git identity, so the gotcha
describing it is updated to record the failure it now provokes.
Each generation stores a kernel and an initrd on the EFI system partition,
and this host runs a large third-party kernel, so 512 MiB holds only about
seven. An exhausted partition fails at bootloader installation, after the
build has already succeeded.
The partition cannot grow in place: it sits first on the disk with the
encrypted container immediately behind it, and an encrypted volume's start
offset cannot move without rewriting its whole payload. Only an install
applies this layout, so the change takes effect at the next reimage and
does nothing to the running machine until then.
Record that a flake only sees git-tracked files, which cost an evaluation
earlier, and correct the git identity gotcha that a hand-written gitconfig
had made false.
The rebooted laptop selects deep sleep, runs thermal and power management,
and no longer loads the PS/2 mouse driver. Booted, running and freshly
built toplevels are the same store path, so the readings come from this
configuration rather than a surviving generation.
The laptop's hardware facts were guessed before it ran NixOS. Hand them to
the upstream nixos-hardware profile for this exact model, which fixes four
things that are wrong on the running machine: the laptop suspends into
s2idle rather than deep S3, the PS/2 mouse driver loads over an i2c
touchpad, no thermal management runs, and firmware updates are impossible.
The profile is taken wholesale, including the Intel graphics support it
carries. Those packages are inert without a display server, and trimming
them would mean diverging from upstream for no present benefit.
Drop the host's own Intel microcode setting, which the profile now defaults
from the redistributable firmware already enabled here.
The input follows the base nixpkgs: only its NixOS modules are consumed, so
its own pin would be evaluated by nothing while drifting silently.
The two acceptance criteria needing a reboot are left open; the sleep mode
and module blacklist only take effect on a fresh boot.
Only the hardware profile needs to precede the reimage, because it is the
one change that touches boot: a kernel parameter and a module blacklist.
Validating it while a known-good generation still exists means the reimage
installs a configuration already proven on this hardware, where a freshly
imaged machine has no rollback target.
The housekeeping and commit-identity changes carry no boot risk and apply
equally well after the wipe, so they no longer gate it. The case for
reimaging soon rests on the machine holding almost nothing, and that
weakens with every day of use.
neogaia was installed from a configuration written before the hardware
existed, so several things are now knowably wrong rather than guessed.
Adopt the upstream hardware profile for this laptop, which fixes deep
sleep, thermal management and the touchpad driver. Bound the store, the
retained generations and the boot menu, none of which have a limit today.
Declare the commit identity, which currently lives only in one checkout.
Grow the EFI system partition, which holds around seven generations at
its present size and cannot be enlarged in place, since the encrypted
container immediately behind it would have to be relocated. That makes a
reimage the only practical route, and the cheapest moment for one is now.
It doubles as the reproducibility test of the install documentation.
Supersede ADR 0001's SSH-derived key mechanism with an admin identity held
outside the repo plus a per-host identity on each encrypted root. Decoupling
the two is what lets the SSH host keys become secrets themselves rather than
the root of trust they were.
Add the spec, the three implementing tasks, and the glossary terms the
breakdown speaks in.
Add docs/install.md, the operator runbook that turns the completed
neogaia Host into a running encrypted laptop from the NixOS live ISO:
push the flake to its remote, join wifi, clone the repo locally,
disko-install against neogaia with the chaotic substituter handed to the
install-time daemon, set the bootstrap login password by hand via
nixos-enter, and reboot.
Bring the declarative half of ~/.claude into modules/claude-code and apply
it when the Module is enabled: the global agent instructions (context =
./CLAUDE.md), the skills tree (skills = ./skills), the attention-bell hook,
and settings.json (model = opus plus the Stop/Notification/SessionStart
hook wiring).
Runtime state (projects, plugins, cache, history, sessions) and the
.credentials.json secret are left out, so login survives rebuilds and no
secret enters the repo. Verified against the built home-files that
~/.claude/{CLAUDE.md,settings.json,skills,hooks/attention-bell.sh} are
generated, the hook executable.
Install Claude Code through home-manager's native programs.claude-code
module, matching how the tmux and fish Modules use their home-manager
options rather than a raw home.packages entry. The feature Module at
modules/claude-code/claude-code.nix stays thin — just the enable option
and the delegation — and writes no settings, so login and first-run
configuration remain interactive and no auth material enters the repo.
Signing in without a browser (needed over the console or SSH) is
documented in modules/claude-code/authentication.md: the paste-code OAuth
flow, where the printed URL is opened on another device and the code
pasted back, and the ANTHROPIC_API_KEY path for non-interactive use.
The neogaia toplevel builds with claude-code-2.1.209 included.
Add an nvim Module that configures Neovim declaratively through nixvim,
wired as a flake input and consumed as its home-manager module. Options,
globals, keymaps, and plugin settings are typed Nix; the colorscheme
call and two autocmds live in modules/nvim/config.lua via extraConfigLua.
Plugins come from nixpkgs (no plugin manager, no runtime cloning); git,
ripgrep, and fd are provided from Nix; treesitter grammars are built by
Nix so no runtime compiler is needed.
Functionally matches the previous config (plugins, keymaps, options, the
nord colorscheme, markdown conceal, the Neogit blame toggle), verified
headless against the generated init.
Configure tmux through home-manager's programs.tmux: the settings it exposes
as options (prefix, keyMode, mouse, baseIndex, clock24, escapeTime,
historyLimit, terminal) are set as options, and every setting it has no option
for is read verbatim from modules/tmux/extra.conf. No tmux plugin manager is
used. The generated config is behaviourally identical to the reference, verified
by parsing it with a live tmux binary.
The interactive init is small; four fragment files was over-splitting it.
Keep the mechanic (a real fish file inlined by Nix into config.fish) but
merge the fragments into a single modules/fish/config.fish read with
builtins.readFile. Rendered config is unchanged.
Break the interactive init into concern-scoped fish files under
modules/fish/config/ (bindings, env, done, path) and assemble them with
lib.concatMapStringsSep + readFile into a single interactiveShellInit, so
home-manager still writes one ~/.config/fish/config.fish. The pieces stay
editable as separate fish files; the rendered file is unchanged.
Fold the done plugin tuning back into config.fish and drop the conf.d
fragment: config.fish is read whole into interactiveShellInit, so Nix
assembles the interactive init at build time instead of fish autoloading
a separate conf.d file. functions/copy.fish stays a function file, the
idiomatic home for a lazily-autoloaded function.
Move the Module to modules/fish/fish.nix and mirror a real fish config
directory beside it: config.fish (interactive init), conf.d/done.fish
(the done plugin tuning, now a real conf.d file), and functions/copy.fish.
completions/ and themes/ are omitted as they have no content and git
cannot track empty directories.
Move the login-shell switch behind a new modules.fish.defaultShell
option (default false; neogaia opts in). Convert every non-eza alias to
an abbreviation, set preferAbbrs and pin generateCompletions, and switch
the command line to vi-style editing. Cap navigation at four dots and
drop psmem/psmem10/dir/vdir/please. Comment the installed packages.
Translate the CachyOS fish snapshot into a home-manager Module: the
fastfetch greeting, the bat-backed manpager, the done and bang-bang
plugins (from nixpkgs, not a plugin manager), the history/backup/copy
helper functions, and the eza and navigation aliases. Pacman-specific
aliases are dropped or replaced with NixOS equivalents (update ->
nixos-rebuild switch, cleanup -> nix-collect-garbage). Enabling the
Module also makes fish the user's default login shell.
Turn the booted laptop into a usable, remotely reachable console: enable
NetworkManager so wifi can be joined from the console and an SSH daemon so
the rest of the setup can be driven over the network. Set the base locale to
timezone America/New_York, locale en_GB.UTF-8, and console keymap us.
These live inline in the neogaia Host rather than behind enable Modules,
matching the single-Host MVI precedent; a shared locale/networking Module can
be extracted once a second Host needs the same settings. SSH keeps default
password auth on, as first-boot access relies on the hand-set bootstrap
password until key/sops-based auth lands post-install.
modules/zram.nix only wrapped the native zramSwap.enable toggle without
adding anything. Rewrite the touched comments to describe only the current
file content, and record the in-file-comment convention in CLAUDE.md.
Select the CachyOS kernel per-Host via boot.kernelPackages, enable Intel
microcode and redistributable firmware (ath10k for the QCA6174 wifi), and
move zram behind a toggle Module. Declare the chaotic binary cache in the
base Nix settings (extra-substituters/keys) so the built system fetches the
kernel from nyx-cache rather than compiling it.
Add disko as a flake input (following nixpkgs) and wire its NixOS module
into the host-builder, so any Host can declare a disk layout while the
layout itself stays a per-Host concern.
neogaia's layout (hosts/neogaia/disk.nix): one GPT NVMe disk with a
systemd-boot EFI system partition and a LUKS container holding btrfs with
@root/@home/@nix subvolumes. The initrd prompts for the passphrase on a
normal boot. Swap is RAM-backed zram, so there is no on-disk swap
partition; zramSwap is enabled directly for now. The placeholder
fileSystems are removed since disko now derives them.
26.05 is the latest stable NixOS release as of now (26.11 is still the
in-development branch that nixos-unstable reports); the previous 25.05 pin
was a release behind.
- flake.nix / flake.lock: stable overlay tracks nixos-26.05.
- neogaia system.stateVersion and the base home.stateVersion set to 26.05
(fresh install, so aligning to the current stable release).
- Refresh the "latest stable release" references in the project docs to
match.
Other inputs are rolling branches (nixos-unstable, nixpkgs-unstable,
chaotic nyxpkgs-unstable) or master (home-manager, per spec), so they carry
no version to bump.
Stand up the walking skeleton the rest of the laptop MVI extends and
re-verifies against: the whole neogaia Host evaluates and its system
toplevel builds (nix flake check green).
- flake.nix: hand-rolled flake (no flake-parts). Base nixos-unstable, plus
nixpkgs-unstable and nixos-25.05 for the per-package unstable/stable
overlays, home-manager (nixpkgs followed), and chaotic-nyx (deliberately
not following our nixpkgs, to keep its binary cache usable). checks build
each Host toplevel.
- lib/: trimmed helper lib — the Auto-loader (recursive .nix discovery, no
null-placeholder hack), the host-builder, and the script-from-file helper.
Deps inherited explicitly; no with lib.my, no nixosModules output.
- system/: shared base config — the unstable/stable overlays, the user
option (defaults to alexion, in wheel, drives system + home-manager user
in lockstep), flakes, git, and home-manager as a NixOS module.
- modules/example.nix: Auto-loader / Enable-convention reference Module,
inert until enabled.
- hosts/neogaia/: minimal laptop Host — placeholder filesystems, bootloader,
and hardware profile.
- CLAUDE.md: project agent instructions with a Gotchas section (nix on the
CachyOS dev host, the chaotic overlay/cache behaviour, the Gitea CLI).
