docs: Add infrastructure overview

Document the module architecture, deployment workflows, installer, and high-level box map.
2026-08-01 23:51:26 +01:00
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+# Deployment documentation
+
+> **Note:** these pages are a work in progress and were **agent-generated** from the repository.
+> They may be incomplete or out of date — treat the Nix configuration as the source of truth.
+
+This directory documents the boxes managed by this flake: their roles, network assignments,
+hierarchy, and the services they run. For the mechanics of the repo itself (conventions, module
+system internals for contributors, agent guidance), see [`AGENTS.md`](../AGENTS.md).
+
+The two big sites follow the pattern:
+
+```
+physical host (VM host)
+└── VM (for things impractical to containerise)
+    └── container host VM
+        └── NixOS containers (one per application group)
+```
+
+Not every box fits this pattern, but **colony** and **home** are organised this way.
+
+## General
+
+- [`architecture.md`](architecture.md) — the custom module system, `my.*` namespace, multiple
+  nixpkgs channels, shared module inventory.
+- [`networking.md`](networking.md) — network assignments, domains, site topologies, router HA,
+  the AS211024 L2 mesh, BGP, WireGuard, Tailscale.
+- [`deployment.md`](deployment.md) — deploy-rs, devshell commands, secrets workflow, CI.
+- [`reference/nixos-options.md`](reference/nixos-options.md) — generated per-option reference for
+  the custom `my.*` NixOS modules.
+
+## Site: colony (Amsterdam)
+
+Physical host and public-infrastructure hub — see [`sites/colony/README.md`](sites/colony/README.md).
+
+```
+colony (physical VM host, ams1)
+├── estuary ── edge router: WAN, firewall/NAT, DNS, BGP (AS211024), WireGuard
+├── shill ──── NixOS container host ──┬── middleman    (reverse proxy, ACME, nginx-sso, librespeed)
+│                                     ├── vaultwarden  (password manager)
+│                                     ├── colony-psql  (shared PostgreSQL)
+│                                     ├── chatterbox   (Matrix Synapse + bridges)
+│                                     ├── jackflix     (media stack)
+│                                     ├── object       (MinIO, Harmonia Nix cache, Sharry, HedgeDoc, wastebin)
+│                                     ├── toot         (Bluesky PDS; Mastodon disabled)
+│                                     ├── waffletail   (Tailscale subnet router / exit node)
+│                                     ├── qclk         (WireGuard management appliance)
+│                                     ├── gam          (Terraria server)
+│                                     └── jam          (raw nspawn customer container)
+├── whale2 ─── podman/OCI host for game servers
+├── git ────── Gitea + Gitea Actions runner
+├── mail ───── Debian VM running mailcow (not NixOS)
+└── darts ──── third-party/customer VM (opaque, not NixOS)
+```
+
+## Site: home
+
+Redundant routers, VM host, storage, IoT containers and the workstation — see
+[`sites/home/README.md`](sites/home/README.md). The hand-configured switch fabric (jim/dave/brian)
+and the Digiweb WAN path are documented in [`sites/home/switches.md`](sites/home/switches.md).
+
+```
+h.nul.ie
+├── palace (physical VM host — AMD, 100G, SR-IOV)
+│   ├── river ── primary router VM (PPPoE / Digiweb WAN)
+│   ├── cellar ─ NVMe-oF / SPDK storage target VM
+│   └── sfh ──── container host VM ("services for home")
+│       ├── hass ── Home Assistant + Frigate + MQTT (container)
+│       └── unifi ─ UniFi controller (container)
+├── stream (physical secondary router — Virgin Media WAN)
+└── castle (workstation / gaming desktop — netboot, NVMe-oF root)
+```
+
+## Remote boxes
+
+The edge VPSes and remote `kelder` site are indexed in [`remote/README.md`](remote/README.md).
+
+## Mobile boxes
+
+The laptop is indexed in [`mobile/README.md`](mobile/README.md).
+
+## Misc
+
+- [`misc/installer.md`](misc/installer.md) — the custom NixOS installer image.
+
+## A note on the assignment tables
+
+The consolidated [`Box assignments`](networking.md#box-assignments) tables in
+[`networking.md`](networking.md) (one per site, between `<!-- assignments: <site> -->` markers)
+are **generated from the flake** (`nixos.allAssignments`) by `nix run .#update-docs-assignments` —
+CI refreshes them on push. Individual box pages link to that section rather than carrying their
+own table. Only the Notes column is hand-written; don't hand-edit the other cells.
@@ -0,0 +1,266 @@
+# Architecture
+
+This flake does **not** use the stock pattern of calling `nixosSystem` once per host in
+[`flake.nix`](../flake.nix). Instead it runs a single `lib.evalModules` evaluation over its own
+module tree, producing one big top-level config (`self.nixfiles`) from which the real flake
+outputs (`nixosConfigurations`, `homeConfigurations`, `nixosModules`, `deploy`, …) are derived.
+Per-host files declare *options* (`nixos.systems.<name>`); the machinery in
+[`nixos/default.nix`](../nixos/default.nix) and
+[`home-manager/default.nix`](../home-manager/default.nix) turns those into evaluated NixOS /
+home-manager configurations.
+
+## The top-level evaluation
+
+`flake.nix`'s `outputs` builds a `nixfiles` attrset via `evalModules` over:
+
+- An inline module that seeds `_module.args` (`lib`, `pkgsFlakes`, `hmFlakes`, `self`, `inputs`,
+  `pkgs'`), sets `nixos.secretsPath = ./secrets`, and sets the global deploy-rs SSH option
+  `deploy-rs.deploy.sshOpts = [ "-i" ".keys/deploy.key" ]`.
+- `nixos/modules/misc/assertions.nix` from the unstable nixpkgs (so the top-level evaluation has
+  the standard `assertions` / `warnings` options).
+- [`nixos/`](../nixos/default.nix) — defines `nixos.*` options (`systems`, `modules`,
+  `allAssignments`, `vpns`, `secretsPath`) and `mkSystem`.
+- [`home-manager/`](../home-manager/default.nix) — defines `home-manager.*` options (`homes`,
+  `modules`) and `mkHome`.
+- [`deploy-rs.nix`](../deploy-rs.nix) — defines `deploy-rs.*` and renders the deploy config.
+- Every file in the `configs` list — the boxes themselves
+  ([`nixos/boxes/`](../nixos/boxes) plus [`nixos/installer.nix`](../nixos/installer.nix); the
+  home-manager entries are currently commented out, see [Home-manager](#home-manager)).
+
+The resulting `nixfiles.config` is mapped onto flake outputs:
+
+| Top-level option (`nixfiles.config`) | Flake output |
+|---|---|
+| `nixos.systems.<name>.rendered` | `nixosConfigurations.<name>` |
+| `home-manager.homes.<name>.configuration` | `homeConfigurations.<name>` |
+| `nixos.modules` | `nixosModules` |
+| `home-manager.modules` | `homeModules` |
+| `deploy-rs.rendered` | `deploy` |
+
+`nixfiles` itself is also a flake output, so anything in the top-level config can be addressed
+directly — e.g. `build-iso` builds
+`.#nixfiles.config.nixos.systems."<host>".configuration.config.my.buildAs.iso`. The flake also
+exposes `lib` (the extended unstable nixpkgs lib, including `lib.my`), `inputs`, `nixpkgs`
+(the `pkgs'` channel sets), and `overlays.default` (the custom packages from
+[`pkgs/`](../pkgs/default.nix)).
+
+Per platform (`eachDefaultSystem`), the flake produces:
+
+- `packages` — everything from `pkgs/`, flattened.
+- `checks` — every `homeConfigurations.*.activationPackage` plus deploy-rs's own `deployChecks`.
+- `devShells.default` — the `numtide/devshell` from [`devshell/`](../devshell) (see
+  [deployment.md](deployment.md)).
+- `ci.<system>` — one attr per buildable thing (`system-<name>`, `home-<name>` with `@` mangled
+  to `-at-`, `package-<name>`, plus `shell`), consumed by CI; `ciDrv` is a `linkFarm` of all of
+  them.
+
+## Systems: `systemOpts` and `mkSystem`
+
+Each entry of `nixos.systems` is a submodule defined by `systemOpts` in
+[`nixos/default.nix`](../nixos/default.nix):
+
+| Option | Type / default | Meaning |
+|---|---|---|
+| `system` | enum of `defaultSystems` | Nix platform string, e.g. `"x86_64-linux"`. |
+| `nixpkgs` | one of `unstable`/`stable`/`mine`/`mine-stable`, default `"unstable"` | nixpkgs channel for the system. |
+| `home-manager` | same enum, defaults to `nixpkgs` | home-manager channel. |
+| `hmNixpkgs` | same enum, defaults to `nixpkgs` | nixpkgs channel used for home-manager's own pkgs when it doesn't share the system's. |
+| `docCustom` | bool, default `false` | Include nixfiles' custom modules in the generated NixOS manual (slow). |
+| `assignments` | attrsOf `assignmentOpts` | The box's network assignments (see [networking.md](networking.md)). |
+| `extraAssignments` | attrsOf attrsOf `assignmentOpts` | Extra assignments for things not on the box itself (e.g. the routers' floating VIP entries). |
+| `configuration` | custom merged type | The actual NixOS configuration module(s); merging runs `mkSystem`. |
+| `rendered` | unspecified, default `configuration` | What ends up in `nixosConfigurations.<name>` — overridden for boxes built as something other than a plain system (e.g. `installer` renders `config.my.asISO`, containers render `config.my.asContainer`). |
+
+`mkSystem` does the real work:
+
+1. It selects the channel's nixpkgs flake (`pkgsFlakes.${config'.nixpkgs}`).
+   - It imports `nixos/lib/eval-config.nix` **by hand** because the flake force-sets `lib`;
+     otherwise `eval-config.nix` would import its own unextended copy.
+   - The supplied library is the channel's `pkgs.lib` extended with `lib.my` and a
+     `versionOverlay` that stamps `system.nixos` with the flake revision and channel.
+2. `specialArgs` gives every module access to `self`, `inputs`, `pkgsFlakes`, the box's own
+   `pkgsFlake`, `allAssignments` (every box's assignments), and `systems` (all of
+   `nixos.systems`). Passing these via `specialArgs` (rather than module `imports`) avoids
+   infinite recursion.
+3. The module list is: the home-manager channel's `nixosModules.default`, every module in
+   `nixos.modules` (the shared modules, see below), an inline module, and the box's own
+   `configuration` definitions (wrapped with `inlineModule'` so error messages keep file
+   provenance).
+4. The inline module wires the plumbing:
+   - `_module.args`: `secretsPath`, `vpns` (the flake-level `nixos.vpns`), the box's own
+     `assignments`, and `pkgs'` — an attrset of **all four nixpkgs channels** for this box's
+     platform, so a module can grab a package from another channel (e.g. `pkgs'.stable.foo`).
+   - `system.name` is the attribute name of the box.
+   - `networking.hostName` / `networking.domain` default from the `internal` assignment (see
+     [networking.md](networking.md)).
+   - `nixpkgs.system` is set and the overlays computed at flake level (lib overlay + custom
+     packages) are passed through, so `pkgs` is imported modularly with config and overlays
+     applied.
+   - `home-manager.useGlobalPkgs` defaults to true when the system and home-manager channels
+     match; a warning is emitted when they deliberately differ.
+   - `home-manager.sharedModules` includes every module in `home-manager.modules` plus an inline
+     module. The inline module passes `pkgsPath` / `pkgs'`, disables the release check, and pins
+     `home.stateVersion` through `homeStateVersion` (`22.11` for stable-flavoured channels,
+     `23.05` otherwise).
+5. Finally `applyAssertions` throws with all failed assertion messages (and shows warnings)
+   when the merged configuration is forced.
+
+## The four nixpkgs channels
+
+`flake.nix` builds `pkgsFlakes` (nixpkgs) and `hmFlakes` (home-manager):
+
+| Channel | nixpkgs input | home-manager input |
+|---|---|---|
+| `unstable` | `nixpkgs/nixos-unstable` | `home-manager` (master) |
+| `stable` | `nixpkgs/nixos-26.05` | `home-manager/release-26.05` |
+| `mine` | `github:devplayer0/nixpkgs/devplayer0` (personal fork) | alias of `unstable` (no fork exists) |
+| `mine-stable` | `github:devplayer0/nixpkgs/devplayer0-stable` | alias of `stable` |
+
+Each channel's `lib` is extended with the `libOverlay` (`lib.my` + flake-utils). Two package
+sets are built per channel:
+
+- `pkgs'` — with the devshell/ragenix/deploy-rs/home-manager overlays; used for the dev shell
+  and `packages`, and exposed as the flake's `nixpkgs` output.
+- `configPkgs'` — with just the lib + custom-packages overlays and an `allowUnfreePredicate`
+  (Widevine / Chromium); this is the `pkgs'` threaded into the top-level evaluation, from
+  which each box's `pkgs` and per-channel `pkgs'` module args (and home-manager's base
+  `pkgs`) are taken.
+
+A box picks its channel with `nixpkgs = "mine"` (most boxes), `"mine-stable"` (e.g. `colony`),
+etc. Inside a module, `pkgs` is the selected channel and `pkgs'` is the attrset of all four
+(`pkgs'.<channel>.<attr>`).
+
+## `lib.my` and the `my.*` namespace
+
+[`lib/default.nix`](../lib/default.nix) extends nixpkgs `lib` with a `my` attrset. The
+flake-level `lib` (`pkgsFlakes.unstable.lib` so extended) is for platform-independent flake
+use only; each box gets its own channel's lib extended the same way. Contents:
+
+- **Option helpers** — `mkOpt'`, `mkBoolOpt'`, `nullOrOpt'`, `mkDefault'` (slightly stronger than
+  `mkDefault`), `mkVMOverride'`, `inlineModule'` / `inlineModule`
+  (attach `_file` provenance), `commonOpts` (the shared `system`/`nixpkgs`/`home-manager`
+  options and the `moduleType` used for exported modules), `applyAssertions`, `duplicates`.
+- **`lib.my.net`** — CIDR/IP math (`net.cidr.host`, `net.cidr.subnet`, `net.types.ipv4`, …)
+  from the `libnetRepo` input (`oddlama/nixos-extra-modules`' `netu.nix`). Used for nearly all
+  address arithmetic; addresses are almost never written literally.
+- **`lib.my.c`** — shared constants from [`lib/constants.nix`](../lib/constants.nix): static
+  UID/GID assignments, kernel package selection (`kernel.lts`/`kernel.latest`), nginx config
+  snippets, networkd snippets (`networkd.noL3`), the binary-cache settings (`nix.cache`),
+  and the per-site domains/prefixes/VIPs described in [networking.md](networking.md).
+- **`lib.my.dns`** — zone-generation helpers from [`lib/dns.nix`](../lib/dns.nix): `fwdRecords`
+  / `ptrRecords` / `ptr6Records` rendered from `allAssignments`, plus the LUA-record helpers
+  (`ifaceA`, `lookupIP`) used by the home routers.
+- **networkd helpers** — `networkdAssignment` (assignment → `systemd.network` network, see
+  [networking.md](networking.md)), `mkVLAN`, `dockerNetAssignment`.
+
+### Misc
+
+The remaining helpers are `mkDefaultSystemsPkgs`, `flakePackageOverlay` (wrap another flake's
+package as an overlay), `isIPv6` / `parseIPPort` / `netBroadcast`, `nft` chain-name helpers,
+`systemdAwaitPostgres`, `vm.*` LVM disk descriptors for the `vms` module, the typed `deploy-rs`
+option definitions (`lib.my.deploy-rs`), `netbootKeaClientClasses` (iPXE/EFI DHCP client classes),
+and `homeStateVersion`.
+
+Custom NixOS / home-manager modules declare their options under the `my.*` namespace (the root
+`options.my` is declared in `nixos/modules/common.nix` / `home-manager/modules/common.nix`) —
+e.g. `my.secrets`, `my.build`, `my.tmproot`, `my.firewall`, `my.server`, `my.deploy`,
+`my.vms`, `my.containers`.
+
+## Shared modules
+
+Registered in [`nixos/modules/_list.nix`](../nixos/modules/_list.nix) and applied to **every**
+system (box files opt in per-feature via `my.*` options). The table below is the overview — what
+each module is *for*; for the exhaustive, CI-generated per-option reference (types, defaults,
+descriptions) see [`reference/nixos-options.md`](reference/nixos-options.md).
+
+| Module | Provides |
+|---|---|
+| `common` | Baseline for all boxes: imports the impermanence, ragenix (age), sharry, copyparty and harmonia NixOS modules; pins `system.stateVersion`; `doas` instead of `sudo`; immutable users; nix settings (flakes, `ca-derivations`, the `nix-cache.nul.ie` substituter); declares the `my` option root. |
+| `user` | `my.user` — the primary user: `users.users` + matching `home-manager.users` entry, wheel/doas, SSH authorized key from `.keys/me.pub`, shell taken from the home config, home persistence under tmproot. |
+| `build` | `my.build` — alternate build targets via `extendModules`: `my.buildAs.devVM` (QEMU dev VM), `iso`, `container`, `kexecTree`, `netbootTree`/`netbootArchive`; `my.build.isDevVM` marker; `allHardware` profile toggle. |
+| `dynamic-motd` | `my.dynamic-motd` — runs a script via `pam_exec` to generate the MOTD on login/ssh. |
+| `tmproot` | `my.tmproot` — tmpfs `/` plus impermanence persistence (`persistence.dir`), with a `tmproot-unsaved` helper that walks the root tmpfs and lists files not covered by persistence. |
+| `firewall` | `my.firewall` — nftables firewall: `tcp.allowed`/`udp.allowed` port lists, `trustedInterfaces`, NAT with `forwardPorts`, `extraRules` escape hatch; sane ICMP/ICMPv6/PMTUD rules baked in. |
+| `server` | `my.server.enable` — server commonalities: getty autologin, LLMNR off, tightened fstrim timers, GUI and NixOS documentation off. |
+| `deploy-rs` | `my.deploy` — per-box deploy-rs node/profile generation and the `deploy` user; see [deployment.md](deployment.md). |
+| `secrets` | `my.secrets` — ragenix/agenix wiring: `files` to decrypt from `secrets/`, host `key` to encrypt for, identity paths derived from the OpenSSH host keys (persistence-aware), dev-key identity inside dev VMs. |
+| `containers` | `my.containers.instances` — `systemd-nspawn` NixOS containers whose systems come from `nixos.systems` rendered `asContainer`, with bridge/macvlan networking, bind mounts, `hotReload` (reload instead of reboot) and a placeholder "dummy" init before first deploy. |
+| `vms` | `my.vms.instances` — QEMU/KVM VMs as systemd units: TAP/bridge networking, LVM-backed disks, VFIO host-device passthrough (with udev tagging), UEFI, SPICE/TTY/QMP unix sockets under `/run/vms/`, clean shutdown via QMP `system_powerdown`. |
+| `network` | Baseline networking: networkd only (`useDHCP = false`), IPv6 on, resolved domain/negative-cache settings; dev VMs get DHCP on `eth0` and an SSH port forward. |
+| `pdns` | `my.pdns` — PowerDNS: authoritative server driven by BIND-style zone files (with templating and serial management) and recursor extra-settings wiring. |
+| `nginx-sso` | `my.nginx-sso` — runs `nginx-sso` (instead of the stock NixOS module) and generates per-instance nginx `auth_request` include files. |
+| `gui` | `my.gui.enable` (default on) — desktop baseline: graphics, polkit, swaylock PAM entry, Android udev rules, screenshot tmpdir. |
+| `l2mesh` | Consumes `nixos.vpns.l2` — builds the VXLAN + IPsec layer-2 meshes between edge routers; see [networking.md](networking.md). |
+| `borgthin` | `my.borgthin.jobs` — borg backups of thin-LVM snapshots to local or SSH repos on a systemd timer, with pruning. |
+| `nvme` | `my.nvme` — sets the NVMe host NQN/hostid and, optionally, NVMe-oF-over-RDMA boot in the initrd. |
+| `spdk` | `my.spdk` — SPDK target configuration (JSON RPC-driven) plus `spdk-rpc`/`spdk-setup`/`spdk-debug` helper tools. |
+| `librespeed` | `my.librespeed` — a LibreSpeed speedtest: generated frontend (from the `librespeed-go` package in `pkgs/`) plus backend settings. |
+| `netboot` | `my.netboot` — iPXE netboot server (TFTP/HTTP, menu) and the client-side loader that installs boot entries. |
+
+Home-manager modules, registered in
+[`home-manager/modules/_list.nix`](../home-manager/modules/_list.nix) and applied to every
+home (including the per-user homes attached to systems via `my.user.homeConfig`):
+
+| Module | Provides |
+|---|---|
+| `common` | Home baseline: `my.shell`, `my.ssh.authKeys`, `my.isStandalone` (home-manager running standalone vs inside NixOS), fish setup and completions generation, common programs. |
+| `gui` | `my.gui` — the sway-based desktop: waybar, notifications, lock/saver plumbing (including the "doomsaver"), terminal and fonts. |
+| `deploy-rs` | `my.deploy` for standalone homes — generates a `home` profile (home-manager activation) and deploy node; auto-disabled for NixOS-attached homes. |
+| `swaync` | `my.swaync` — typed configuration module for Sway Notification Center. |
+
+## Adding a box
+
+1. Create a file (or directory with a `default.nix`) under [`nixos/boxes/`](../nixos/boxes)
+   that sets `nixos.systems.<name> = { system = "x86_64-linux"; nixpkgs = "mine"; assignments =
+   { … }; configuration = { … }: { … }; };`. Nested boxes (VMs, containers) live under their
+   host's directory (e.g. `nixos/boxes/colony/vms/estuary/`).
+2. Add the path to the `configs` list in [`flake.nix`](../flake.nix).
+3. Give the box an `internal` assignment (name/domain) if it gets one — `hostName`/`domain`
+   default from it — and declare `my.secrets.key` if it has secrets.
+4. Evaluate it with `check-system <name>` (cheap) before `build-system <name>`.
+
+## Adding a shared module
+
+1. Drop the file in [`nixos/modules/`](../nixos/modules) (or
+   [`home-manager/modules/`](../home-manager/modules)) with options under `my.*`, declared via
+   the `lib.my` helpers (`mkOpt'`, `mkBoolOpt'`).
+2. Register it in the corresponding `_list.nix` (name → path). It is then applied to every
+   box and exported as `nixosModules.<name>` / `homeModules.<name>`.
+
+## Home-manager
+
+Home-manager follows the same option-definition and evaluation split as NixOS.
+
+### `homeOpts`
+
+[`home-manager/default.nix`](../home-manager/default.nix) defines each entry with these options:
+
+| Option | Meaning |
+|---|---|
+| `system` | Target platform. |
+| `nixpkgs` | nixpkgs channel used for the home packages. |
+| `home-manager` | home-manager channel. |
+| `homeDirectory` / `username` | User identity and home path. |
+| `configuration` | The home-manager module definitions evaluated by `mkHome`. |
+
+### `mkHome`
+
+1. Calls the selected channel's `lib.homeManagerConfiguration`.
+2. Supplies that channel's `pkgs'` with `config` emptied, allowing home-manager to apply package
+   configuration and overlays through its module system.
+3. Passes `inputs`, `pkgsFlakes` and the selected `pkgsFlake` through `extraSpecialArgs`.
+4. Loads every module in `home-manager.modules` plus an inline module that sets
+   `home.homeDirectory` / `home.username` and exposes every channel through the `pkgs'` module
+   argument.
+5. Pins `home.stateVersion` through `homeStateVersion`.
+
+### Standalone homes
+
+Standalone homes live in [`home-manager/configs/`](../home-manager/configs) and are named
+`<user>@<host>` (deploy-rs mangles the `@` to `-at-`). `macsimum` is a home-manager-only
+config — an `x86_64-darwin` macOS box with no NixOS side.
+
+No standalone homes are currently wired into the flake: `home-manager/configs/macsimum.nix` is
+commented out of `configs`, while `home-manager/configs/castle.nix` is not listed. Consequently,
+`nixfiles.config.home-manager.homes` evaluates to `{}`. Most user configuration instead accompanies
+NixOS boxes through `my.user.homeConfig`.
@@ -0,0 +1,199 @@
+# Deployment and workflows
+
+How boxes get deployed, the devshell commands that drive everyday work, secrets, dev VMs, and
+CI.
+
+## deploy-rs
+
+### Rendering
+
+The top-level [`deploy-rs.nix`](../deploy-rs.nix) renders the flake's `deploy` output:
+
+- It collects `nixos.systems` and `home-manager.homes` (mangling `@` in home names to
+  `-at-`, since deploy-rs node names can't contain `@`). An assertion rejects name collisions
+  between systems and homes.
+- A system/home becomes a deploy node only when `configuration.config.my.deploy.enable` is
+  true. The node config is the *definitions* of the box's `my.deploy.node` option, re-imported
+  as a module so deploy-rs's submodule merging still applies.
+- `autoRollback` and `magicRollback` are off globally; global `sshOpts` are
+  `[ "-i" ".keys/deploy.key" ]` (set in [`flake.nix`](../flake.nix)).
+- The result is passed through `lib.my.deploy-rs.filterOpts`, which strips nulls so unset
+  options don't override deploy-rs defaults, and exposed as `deploy = deploy-rs.rendered`.
+
+### Per-box nodes
+
+The shared [`nixos/modules/deploy-rs.nix`](../nixos/modules/deploy-rs.nix) module provides
+`my.deploy`:
+
+- `my.deploy.enable` defaults to true, but is **automatically forced off for dev VMs and
+  NixOS containers** (`my.build.isDevVM` / `boot.isContainer` — containers are deployed
+  through their host instead, see below). The installer also disables it explicitly.
+- Node defaults: `hostname` = the box's FQDN, `sshUser = "deploy"`, `user = "root"`,
+  `sudo = "doas -u"` (or `sudo -u`), `sshOpts` = the box's first OpenSSH port. The module
+  creates the `deploy` system user (bash shell, wheel, keys from `my.deploy.authorizedKeys`,
+  which defaults to `.keys/deploy.pub`).
+
+Generated profiles deploy in this order:
+
+1. **`system`** activates `config.system.build.toplevel` with `switch-to-configuration switch`,
+   applies the `/tmp` cwd and systemd-boot `loader.conf` workarounds, then prunes old generations.
+   `keepGenerations` controls how much history is retained; zero disables pruning.
+2. **`container-<name>`** activates each `my.containers.instances` entry into
+   `/nix/var/nix/profiles/per-container/<name>/system`. With `hotReload` (the default), it reloads
+   `systemd-nspawn@<name>` and restarts only a stopped container or one still running the dummy
+   init; otherwise it restarts the unit. The same generation cleanup applies.
+
+### Usage
+
+- `deploy .#<host>` — the devshell's `deploy` is a wrapper that adds `--skip-checks`. Node
+  names are the system names (`deploy .#git`).
+- `deploy-multi <hosts...>` — loops `deploy` over several nodes (extra args via `$O`).
+- `deploy --boot .#<host>` — stages the config as the boot default **without** live-switching
+  (deploy-rs's `--boot` maps to the custom activation's `boot` phase, which also does the
+  generation cleanup). Use it when a live `switch` would cut the box off mid-change (e.g. a
+  router WAN rework), then reboot to cut over.
+- `nix flake check` includes deploy-rs's own `deployChecks` for the whole `deploy` attrset.
+
+#### `ssh-machine`
+
+`ssh-machine <name> [cmd]` resolves `user@host` and the merged global/node `sshOpts` from
+`.#deploy`, using the same `my.deploy.enable` gate and `@` → `-at-` mangling as `deploy`, then runs
+`ssh`. Boxes default to `fish`, so pipe multi-statement remote scripts through `bash`, for example
+`ssh-machine <name> bash -s < script.sh`. If a flaky agent stalls public-key authentication, use
+`SSH_AUTH_SOCK= ssh-machine …`.
+
+## Devshell commands
+
+The repo ships a `numtide/devshell` ([`devshell/`](../devshell), entered via `direnv`). Run a
+command with no arguments for its help. From
+[`devshell/commands.nix`](../devshell/commands.nix):
+
+| Command | What it does |
+|---|---|
+| `check-system <host> [nix args]` | Evaluates `.#nixosConfigurations."<host>".config.system.build.toplevel.drvPath` — catches module/option errors without building. Prefer this to validate a config change. |
+| `build-system <host> [nix args]` | Builds the system's `toplevel` (extra args pass through to `nix build`). |
+| `build-n-switch <args>` | `doas nixos-rebuild --flake .` (adds the repo as a git `safe.directory` for root first). |
+| `build-home <name> [nix args]` | Builds `.#homeConfigurations."<name>".activationPackage`. |
+| `home-switch [args]` | `home-manager switch --flake .`. |
+| `deploy [args]` | `deploy-rs --skip-checks` (wrapper package in `devshell/default.nix`). |
+| `deploy-multi <nodes...>` | Deploys several nodes in sequence. |
+| `ssh-machine <name> [cmd]` | SSH to a system or home by name, resolving target/options from its deploy-rs node (see above). |
+| `run-vm <host>` | Boots a system as a dev VM: installs `.keys/dev.key` into a temp `xchg/`, then `nix run`s `config.my.buildAs.devVM`. |
+| `build-iso <host>` | Builds `config.my.buildAs.iso`. |
+| `build-kexec <host>` | Builds `config.my.buildAs.kexecTree`. |
+| `build-netboot <host>` | Builds `config.my.buildAs.netbootTree`. |
+| `ragenix [args]` | `ragenix --identity .keys/dev.key` (see [Secrets](#secrets)). |
+| `repl` | `nix repl .#`. |
+| `fmt [args]` | `nixpkgs-fmt` (the canonical formatter). |
+| `update-nixpkgs` | `nix flake update nixpkgs-{unstable,stable,mine,mine-stable}`. |
+| `update-home-manager` | `nix flake update home-manager-{unstable,stable}`. |
+| `update-installer` | Force-pushes the `installer` tag to trigger the installer release workflow. |
+| `home-link` / `home-unlink` | Symlink (or remove) this `flake.nix` at `~/.config/home-manager/flake.nix` for standalone `home-manager` use. |
+| `qemu-genmac` | Prints a random QEMU-suitable MAC (`52:54:00:xx:xx:xx`). |
+| `ssh-get-ed25519 <host>` | Prints a host's ed25519 pubkey via `ssh-keyscan`. |
+| `json2nix` | Converts JSON on stdin to formatted Nix. |
+
+From [`devshell/install.nix`](../devshell/install.nix) (driven by `$INSTALLER`, the address of
+a running custom installer, SSHing as root with `.keys/deploy.key`):
+
+| Command | What it does |
+|---|---|
+| `installer-shell [cmd]` | Runs a command (default: a shell) inside the installer. |
+| `do-install [--no-bootloader] [--no-substitute] <system>` | Builds the system's `toplevel`, `nix copy`s it into the installer's target store, sets the system profile, and activates it with `switch-to-configuration boot` (with `NIXOS_INSTALL_BOOTLOADER=1` unless `--no-bootloader`). |
+
+From [`devshell/vm-tasks.nix`](../devshell/vm-tasks.nix) (remote VM consoles; they forward the
+VM's unix sockets from `/run/vms/<vm>/` on `<host>` over SSH):
+
+| Command | What it does |
+|---|---|
+| `vm-tty <host> <vm>` | Serial TTY of a VM in `minicom`. |
+| `vm-monitor <host> <vm>` | QEMU monitor socket in `minicom`. |
+| `vm-viewer <host> <vm>` | SPICE display in `virt-viewer` (not on Darwin). |
+
+## Secrets
+
+Secrets are age-encrypted files in [`secrets/`](../secrets), managed with **ragenix** (a fork
+with a rekey flag, from the flake inputs).
+
+### Per-box declarations
+
+Each box declares `my.secrets.key`, the host public key its secrets encrypt to, and
+`my.secrets.files.<name>`, whose values merge settings such as `owner` and `mode` into the agenix
+secret. At runtime, identity paths come from the box's OpenSSH host keys. On tmproot boxes they are
+read from the persistence directory because agenix runs before the persisted keys would otherwise
+be available.
+
+### Recipient rules
+
+[`secrets.nix`](../secrets.nix) is generated from every system's `my.secrets.files` and `key`.
+Each recipient list also includes `.keys/dev.pub`, so the development key can open every secret.
+Run `ragenix -r` after adding a box or secret to re-key the files.
+
+### Local keys and editing
+
+The `ragenix` devshell command wraps `ragenix --identity .keys/dev.key`. The `.keys/` directory
+contains that development key, the deploy key authorized for every box's `deploy` user, and other
+keys referenced by `lib.my.c.sshKeyFiles`; it is required for editing secrets, deploying and running
+development VMs.
+
+## Dev VMs
+
+Any system can be built as a throwaway QEMU VM via `config.my.buildAs.devVM` (the `build`
+module extends the config with `qemu-vm.nix` and sets `my.build.isDevVM`). `run-vm <host>`
+creates a temp dir, installs `.keys/dev.key` as `xchg/dev.key`, and runs the VM; inside, the
+`secrets` module switches `age.identityPaths` to that dev key (`my.secrets.vmKeyPath`,
+default `/tmp/xchg/dev.key`), so dev VMs can decrypt the boxes' secrets without the real host
+keys. Dev VMs also get DHCP on `eth0`, an SSH port forward (host 2222 → guest 22), and are
+automatically excluded from deploy targets.
+
+## CI
+
+GitHub/Gitea Actions workflows live in [`.gitea/workflows/`](../.gitea/workflows).
+
+### `ci.yaml`
+
+On pushes to `master`, this runs `nix flake check --no-build`, then builds every attribute of
+`.#ci.x86_64-linux`: systems as `system-<name>`, homes as `home-<name>` (with `@` changed to
+`-at-`), packages as `package-<name>`, and the development `shell`. Each result is pushed to the
+Harmonia cache with [`ci/push-to-cache.sh`](../ci/push-to-cache.sh).
+
+It then builds `.#ciDrv.x86_64-linux`, a `linkFarm` of all CI attributes, and pushes it with
+`UPDATE_PROFILE=1`. That updates the `nixfiles` profile on the cache box and collects old paths
+according to the workflow's retention setting. The SSH store uses `/var/lib/harmonia`,
+`HARMONIA_SSH_KEY`, and pinned `ci/known_hosts`; clients use `https://nix-cache.nul.ie` through
+`lib.my.c.nix.cache`.
+
+### `installer.yaml`
+
+Pushing the `installer` tag (refreshed by `update-installer`) builds `my.buildAs.iso` and
+`my.buildAs.netbootArchive`, then attaches both to a release.
+
+### `update-docs.yaml`
+
+On pushes to the docs branch, excluding its own commits, this runs
+`nix run .#update-docs-assignments` and `nix run .#update-docs-options` and commits changed outputs
+as `docs: update generated tables`.
+
+### The docs generators
+
+Both are registered in [`pkgs/default.nix`](../pkgs/default.nix) (`writeShellScriptBin`s wrapping
+Python scripts under [`ci/`](../ci)). They leave the worktree unchanged when their output is current;
+the workflow stages `docs/` and uses `git diff --cached --quiet` to decide whether to commit.
+
+`update-docs-assignments` ([`ci/update-docs-assignments.py`](../ci/update-docs-assignments.py))
+evaluates `.#nixfiles.config.nixos.allAssignments` to JSON and rewrites the consolidated
+[`Box assignments`](networking.md#box-assignments) tables in `docs/networking.md` — one table
+per site (`colony` / `home` / `remote`), each between a `<!-- assignments: <site> -->` marker
+and a closing `<!-- assignments-end -->` line. Boxes are grouped by site from their assignment
+domain, and each `Box` cell links to that box's page when one exists. Hand-written text in the
+**Notes** column is preserved across runs (keyed by box + assignment), so notes survive
+regeneration. Individual box pages don't carry tables; they link to the consolidated section.
+
+`update-docs-options` ([`ci/update-docs-options.py`](../ci/update-docs-options.py)) builds the
+`nixos.optionsDoc` output (declared in [`nixos/default.nix`](../nixos/default.nix)) — a
+`nixosOptionsDoc` JSON dump of the custom `my.*` options (declared with `mkOpt'` / `mkBoolOpt'` in
+`nixos/modules/`). It's evaluated against a **minimal synthetic system**, since the shared modules
+apply to every box, so defaults don't pick up a real host's values. The renderer writes
+[`docs/reference/nixos-options.md`](reference/nixos-options.md), one table per module file. The
+whole file is generated; edit the option descriptions in the modules, not the reference. The
+internal `asX` build-target options are marked `internal = true` so they're excluded.
@@ -0,0 +1,41 @@
+# installer
+
+The custom NixOS installer image used to bootstrap new boxes.
+
+- **Source:** [`nixos/installer.nix`](../../nixos/installer.nix)
+- **Host:** — (a build target, not a deployed box)
+
+## Role
+
+- Defines `nixos.systems.installer`, a minimal server system rendered as a bootable ISO via
+  `config.my.buildAs.iso` (`my.asISO`); the same base can also be built as a kexec or netboot
+  tree.
+- Build it with the devshell commands: `build-iso installer` (or `build-kexec installer` /
+  `build-netboot installer`). The `update-installer` command force-tags `installer` to
+  trigger a release rebuild in CI.
+
+## Image contents
+
+- Broad hardware support (`my.build.allHardware` pulls in the nixpkgs all-hardware profile);
+  EFI- and USB-bootable, zstd-compressed squashfs. Volume ID
+  `jackos-<release>-<arch>`, menu label "/dev/player0 Installer", image base name
+  `jackos-installer`.
+- Root SSH with the deploy key authorized (`PermitRootLogin prohibit-password`); a random
+  `installer-<hex>` hostname is set at boot.
+- `INSTALL_ROOT=/mnt` in the session environment, plus a `show-hw-config` alias wrapping
+  `nixos-generate-config --show-hardware-config --root $INSTALL_ROOT`.
+- NixOS documentation enabled, `wpa_supplicant` available but not started, GC and memory-overcommit
+  tuning for low-memory targets, LVM thin and NFS support.
+- No regular user (`my.user.enable = false`), no tmpfs-root management, no NAT, and not a
+  deploy target (`my.deploy.enable = false`).
+
+## Installing a box
+
+The devshell's installer commands ([`devshell/install.nix`](../../devshell/install.nix)) drive
+an install over SSH against a booted installer reachable at `$INSTALLER`:
+
+- `installer-shell` — get a shell on the installer.
+- `do-install <system>` — builds the system's toplevel, `nix copy`s the closure to the
+  installer's `$INSTALL_ROOT` remote store, sets the system profile, touches `/etc/NIXOS`,
+  and runs `switch-to-configuration boot` with `NIXOS_INSTALL_BOOTLOADER=1` (skip the
+  bootloader with `--no-bootloader`, skip substitution with `--no-substitute`).