Fix nix-cache remote-builder trust: stale host key + wrong sshKey path

variables.nix's nixCacheHostKey no longer matched nix-cache's actual SSH host key (confirmed via ssh-keyscan against the live container), so every declaratively-configured client's programs.ssh.knownHosts trusted the wrong key -- distributed builds would fail host-key verification. Also, modules/nix-cache/remote-builder-client.nix hardcoded sshKey to /root/.ssh/nixremote, but the `server` host only has its own default /root/.ssh/id_ed25519 installed (confirmed live via qm guest-agent) -- that file was never even present, so the build machine config pointed at nothing. Standardize on each client's own default identity, matching the per-host-key pattern vars.remoteBuilderAuthorizedKeys already uses instead of a shared/differently-named keypair, and add scripts/secrets/sync-nix-cache-host-key.sh (wired into codex-maintenance.sh's --check) so the host-key drift doesn't silently recur next time nix-cache is rebuilt or recreated. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01V7yVH71vGrDVzovh9UaMu8
Merge pull request 'Authorize this box's SSH key as a nix-cache remote-builder client' (#20 ) from add-claude-builder-key into main
2026-07-20 17:21:12 +00:00 · 2026-07-20 16:31:25 +00:00 · 2026-07-20 16:29:42 +00:00 · 2026-07-20 16:29:42 +00:00 · 2026-07-20 16:20:45 +00:00 · 2026-07-20 15:38:32 +00:00
40 changed files with 1606 additions and 567 deletions
@@ -1,12 +1,13 @@
 keys:
-  - &admin age10nd382a9klsn2mrs60emdtsxe43pht3a0m9p29phfrhy0wfyt3vsq9r667
+  - &admin age1njap586hc0q43kr03g6c8eqhdsmk8zcafkl3f83xwlc2gqhlmfgs4tmwad
  - &docker age19gfn2yedg76dmztm4hncr7vf3r3c9j0qpt4rap7y7gersjk4m3ks2lhd0e
  - &server age1ll6hj5ggruetgjwjfnplpn5xtq35uhlcdflksx3xmnjm6s3uad9sz70jkf
  - &nix-cache age120le4a5l8dh3lyfgvmj3d9ksmej6ajs5mer5y7r0vfg3x9fn69dqf8xgzu
  - &lxc-minimal age1qz9d4ka4xgexujyd247s7lp737sulp5fhxl5d65fj2ykvc4j4edqrsdks8
  - &nix-minimal age120whqj96g26lsgy4udvgsn8dc9lumh8jeu3a564fx79rjr5lxffqmrljuu
-  - &lxc-nix-cache age164px2a8e48ptsf9ngtan38aa6jls4jdl26mzrgzf6sn3vcvt49hqjrgr8w
  - &proxmox-minimal age10at8862478urh0eeuwh8hzln6ck78jgwtztgxatwqlzwagg77y5snm4xzg
+  - &lxc-nix-cache age1xjst4frdh0th6q8m7p7u9g5af7ty5jqeum0p6z8a52a9q7st7ewqw8yl9j
+  - &lxc-docker age1ezk9x53zt8kcnscdm80jcyf0xq97vndv7jsn3rl8cc0cwm2jmpmq372dzs

 creation_rules:
  # Shared across every currently-deployed host: root/nixos password hash,
@@ -24,6 +25,7 @@ creation_rules:
          - *nix-minimal
          - *lxc-nix-cache
          - *proxmox-minimal
+          - *lxc-docker

  - path_regex: secrets/nix-cache\.yaml$
    key_groups:
@@ -7,7 +7,7 @@ servers and workstation.

 The flake exposes NixOS configurations named `<platform>-<buildtype>`
 (platforms: `linode`, `proxmox`, `lxc`; build types: `minimal`, `nix-cache`,
-`server`, `docker`, `gui`, `pxe-boot`), generated from `modules/platforms/*`
+`server`, `docker`, `gui`, `pxe-boot`, `tailscale-exit-node`, `tor-relay`), generated from `modules/platforms/*`
 and `modules/build-types/*` by the `mkTarget` function in `flake.nix`. Not
 every combination is built — `pxe-boot` has no `linode` variant. See
 `README.md` for the full current target list; treat `flake.nix` as the
@@ -62,8 +62,9 @@ There is no test suite — "correctness" here means the flake evaluates and
 sweeps: after editing one or two hosts/modules, evaluate just the
 `nixosConfigurations.<host>` you touched (plus any `config.system.build.tarball`
 /`diskoImagesScript`/package output affected) rather than looping over every
-host — `codex-maintenance.sh` evaluates 18 hosts plus every package/tarball/
-image variant now and is slow to run after each small change. Reserve a full
+host — `codex-maintenance.sh` evaluates every `nixosConfigurations` host plus
+every package/tarball/image variant and is slow to run after each small
+change. Reserve a full
 `codex-maintenance.sh` run for changes that plausibly affect every host
 (`modules/common/*`, `flake.nix`, `variables.nix`) or as a final check before
 committing. This is a session-workflow preference only — it does not apply to
@@ -72,21 +73,71 @@ diff size; that's the point of it.

 ## Scripts

-Beyond `codex-setup.sh`/`codex-maintenance.sh` above, `scripts/` also has:
+Beyond `codex-setup.sh`/`codex-maintenance.sh` above, `scripts/` is
+organized by purpose: `scripts/secrets/` (sops/age + SSH host-key
+management), `scripts/proxmox/` (Proxmox deployment), `scripts/lib/`
+(shared helpers, sourced by the scripts below — not run directly), and a
+handful of repo-wide scripts left at the top level (`env.sh`,
+`bump-nixpkgs-release.sh`, plus `codex-setup.sh`/`codex-maintenance.sh`
+above). When adding a new script, put it in the matching subfolder rather
+than the top level, and if it duplicates logic another script already has,
+lift the shared part into `scripts/lib/` instead of copying it.

- `scripts/sync-host-keys.sh` — generates/registers SSH host keys and their
-  `.sops.yaml`/`secrets/*.yaml` recipients for flake targets, idempotently
-  (`--all`, `<target>`, `--remove`, `--regenerate-all-keys`, all with
-  `--dry-run`). The primary tool for provisioning a new host's secrets
-  access — see "Creating a new machine" in `docs/auto-installer.md`.
- `scripts/prepare-host-key.sh` — narrower predecessor: generates a key by
-  an arbitrary name without touching `.sops.yaml`. Still useful to
+### `scripts/secrets/`
+
+- `scripts/secrets/sync-host-keys.sh` — generates/registers SSH host keys
+  and their `.sops.yaml`/`secrets/*.yaml` recipients for flake targets,
+  idempotently (`--all`, `<target>`, `--remove`, `--regenerate-all-keys`,
+  all with `--dry-run`). The primary tool for provisioning a new host's
+  secrets access — see "Creating a new machine" in `docs/auto-installer.md`.
+- `scripts/secrets/prepare-host-key.sh` — narrower predecessor: generates a
+  key by an arbitrary name without touching `.sops.yaml`. Still useful to
  pre-generate a key before its flake target exists yet, since
  `sync-host-keys.sh` can only act on targets `nixosConfigurations` already
  has.
- `scripts/create-proxmox-resource.sh` — builds a `lxc-*`/`proxmox-*`
-  target's tarball/disk image and creates it on a real Proxmox node
-  (`pct create` against the tarball as a CT template / `qm create`+
+- `scripts/secrets/rotate-admin-key.sh <backup-admin-key> [--new-key-file
+  <path>] [--dry-run]` — rotates `.sops.yaml`'s `&admin` age key: decrypts
+  with a backed-up copy of the key currently trusted as `&admin` (verified
+  by deriving its public key and comparing, not taken on faith), replaces
+  the `&admin` line with a new key already present in the environment
+  (defaults to wherever sops/age itself would look), and runs
+  `sops updatekeys` on every `secrets/*.yaml`. One-way: the old key can no
+  longer decrypt anything re-encrypted this way. This is the automation
+  for the manual steps `sync-host-keys.sh`/`create-proxmox-resource.sh`
+  print when they bootstrap a brand-new, not-yet-trusted key on a machine
+  with no prior admin access.
+- `scripts/secrets/backup-admin-key.sh <dest-path> [--key-file <path>]
+  [--force] [--dry-run]` — copies the local sops age key (source
+  resolution matches sops/age itself: `$SOPS_AGE_KEY` inline, then
+  `--key-file`, then `$SOPS_AGE_KEY_FILE`, then the XDG default) to an
+  arbitrary destination path with `0600` permissions, validating it's a
+  real age identity and round-tripping the public key before and after the
+  write. Refuses to overwrite an existing `<dest-path>` without `--force`.
+  Purely a local filesystem copy — never touches `.sops.yaml`/
+  `secrets/*.yaml` or the repo at all. The resulting file is exactly what
+  `rotate-admin-key.sh` expects as its backup-key argument.
+- `scripts/secrets/sync-nix-cache-host-key.sh [--check] [--dry-run]
+  [--host <name>]` — detects drift between the ed25519 SSH host key
+  nix-cache is actually serving right now (via `ssh-keyscan`) and
+  `vars.nixCacheHostKey` (`variables.nix`), the value
+  `modules/nix-cache/remote-builder-client.nix` bakes into every real
+  client's declarative `programs.ssh.knownHosts` and
+  `configure-nix-cache-client.sh` hardcodes as its own default for
+  non-NixOS clients. That value has no automatic source of truth — it's
+  set once from whatever nix-cache's host key happened to be at the time,
+  and silently goes stale if the host is ever rebuilt/recreated with a new
+  key, breaking every client's distributed-build SSH trust with no error
+  that points back here. `--check` (used by `codex-maintenance.sh`, which
+  treats an unreachable nix-cache — e.g. from a non-LAN CI runner — as a
+  silent skip rather than a failure) only reports drift; the no-flags form
+  updates both files in place. Declarative clients still need a rebuild to
+  pick up the fix.
+
+### `scripts/proxmox/`
+
+- `scripts/proxmox/create-proxmox-resource.sh` — builds a `lxc-*`/
+  `proxmox-*` target's tarball/disk image and creates it on a real Proxmox
+  node (`pct create` against the tarball as a CT template / `qm create`+
  `importdisk`), or reconfigures an existing resource's cores/memory/disk
  size (`--modify`, always requires typing the VMID back to confirm).
  Checks for an already-uploaded image on the node before building
@@ -96,7 +147,51 @@ Beyond `codex-setup.sh`/`codex-maintenance.sh` above, `scripts/` also has:
  Refuses to create a target whose host identity already exists live on
  the node (checked directly via `qm`/`pct`, not any file in this repo)
  unless `--allow-duplicate-host` is passed. `--dry-run` throughout both
-  modes.
+  modes. The first time it has to bootstrap build tooling on a node (i.e.
+  `nix` wasn't already on its `PATH`), it also runs
+  `scripts/proxmox/configure-nix-cache-client.sh` there (non-fatally — a
+  failure just falls back to building from source / `cache.nixos.org`) so
+  the node substitutes from and can offload builds to nix-cache on every
+  subsequent run, not just this one.
+- `scripts/proxmox/configure-nix-cache-client.sh [--dry-run]
+  [--no-remote-builder] [--no-restart]` — the non-NixOS equivalent of
+  `modules/nix-cache/client.nix`/`remote-builder-client.nix`, for a plain
+  Debian machine with the Nix package manager (not NixOS) already
+  installed: run as root *on that machine* to add nix-cache as a
+  substituter in `/etc/nix/nix.conf` (`https://cache.nixos.org/` kept as
+  fallback) via `extra-substituters`/`extra-trusted-public-keys` so it
+  layers on top of whatever's already there instead of clobbering it, and,
+  if `/root/.ssh/nixremote` is already present (see docs/nix-cache.md
+  "Remote builder SSH keys"), configures it as a distributed-build
+  machine too and trusts nix-cache's SSH host key in
+  `/etc/ssh/ssh_known_hosts`. Idempotent (re-running replaces its own
+  marked block rather than duplicating it); restarts `nix-daemon` by
+  default so the change takes effect immediately.
+
+### `scripts/lib/`
+
+Sourced by the scripts above, never run directly:
+
+- `nix-bootstrap.sh` — `NIX_CONFIG`/`ensure_nix_profile`, shared by
+  `codex-setup.sh`/`codex-maintenance.sh` and the remote build commands
+  `create-proxmox-resource.sh` runs over SSH.
+- `nix-eval.sh` — `NIX_EVAL_FLAGS` plus `list_flake_targets`/
+  `flake_target_hostname` flake-introspection helpers.
+- `ssh-host-keys.sh` — `generate_host_ed25519_key`/`ssh_pubkey_to_age`,
+  shared by `sync-host-keys.sh` and `prepare-host-key.sh`.
+- `sops-age.sh` — `age_pubkey_from_identity_file`/`sops_yaml_admin_pubkey`/
+  `sops_updatekeys` plus the shared sops/age default key-file resolution,
+  shared by `backup-admin-key.sh`, `rotate-admin-key.sh`, and
+  `sync-host-keys.sh`.
+- `confirm.sh` — `confirm_typed`, the "type X back to confirm" destructive-
+  action prompt shared by `create-proxmox-resource.sh` and
+  `sync-host-keys.sh`.
+- `sync-host-keys-edit-sops.py` — the `.sops.yaml` anchor/key_groups editor
+  `sync-host-keys.sh` shells out to (see that script for why: precise,
+  idempotent YAML edits are impractical in bash).
+
+### Top level
+
 - `scripts/env.sh` — shared config (`PROXMOX_HOST`, storage pool, bridge,
  default cores/memory) sourced by `create-proxmox-resource.sh`. Add new
  cross-script config here instead of duplicating it per-script.
@@ -106,12 +201,16 @@ Beyond `codex-setup.sh`/`codex-maintenance.sh` above, `scripts/` also has:
  errors on it), so this is the closest equivalent to a single source of
  truth for the tracked release.

-`sync-host-keys.sh` and `create-proxmox-resource.sh` genuinely mutate real
-state when run for real (not `--dry-run`): real `secrets/*.yaml`
-recipients, real Proxmox VMs/containers. They require the operator's own
-SSH/sops access, which an agent session doesn't have — but don't suggest
-running either non-dry-run without the operator's explicit go-ahead even
-if it becomes technically reachable.
+`sync-host-keys.sh`, `create-proxmox-resource.sh`, and
+`rotate-admin-key.sh` genuinely mutate real state when run for real (not
+`--dry-run`): real `secrets/*.yaml` recipients, real Proxmox VMs/
+containers, real revocation of decrypt access. They require the
+operator's own SSH/sops access, which an agent session doesn't have — but
+don't suggest running any of them non-dry-run without the operator's
+explicit go-ahead even if it becomes technically reachable.
+`backup-admin-key.sh` only writes a key copy to a path the operator gives
+it — lower-stakes than the others, but it still handles a real private
+key, so treat its destination path choice as the operator's call too.

 ## Architecture

@@ -134,9 +233,10 @@ nixosSystem {
 ```

 Platforms: `linode`, `proxmox`, `lxc`. Build types: `minimal`, `nix-cache`,
-`server`, `docker`, `gui`, `pxe-boot`, `tailscale-exit-node`. Not every
-combination is built — e.g. `pxe-boot` has no `linode` variant (PXE/DHCP/TFTP
-need LAN L2 adjacency a Linode VPS doesn't have). Treat `flake.nix`'s
+`server`, `docker`, `gui`, `pxe-boot`, `tailscale-exit-node`, `tor-relay`. Not
+every combination is built — e.g. `pxe-boot` has no `linode` variant
+(PXE/DHCP/TFTP need LAN L2 adjacency a Linode VPS doesn't have), and
+`tor-relay` currently only exists as `lxc-tor-relay`. Treat `flake.nix`'s
 `generatedTargets` as the source
 of truth for which hosts exist — `README.md`, `AGENTS.md`,
 `docs/flake-lock-automation.md`, and the CI eval workflows
@@ -164,7 +264,7 @@ removing a host.
  `vzdump` backup-archive metadata this doesn't have), no install step —
  see `docs/auto-installer.md`.
 - `modules/build-types/*.nix` — what a system is for:
-  minimal/server/docker/gui/pxe-boot/nix-cache.
+  minimal/server/docker/gui/pxe-boot/nix-cache/tailscale-exit-node/tor-relay.
 - `modules/common/configuration.nix` — base NixOS config imported by every
  host: locale, users, nix settings, git.
 - `modules/common/home.nix` / `hosts/nixos/home.nix` — Home Manager config for
@@ -199,7 +299,8 @@ removing a host.
  and `environmentFile`; used by `hosts/server/host.nix` and
  `hosts/nix-cache/host.nix` to avoid duplicating that boilerplate.
 - `modules/tailscale/`, `modules/docker/`, `modules/networking/`,
-  `modules/traefik/`, `modules/services/*` — single-purpose, single-host
+  `modules/traefik/`, `modules/tor/`, `modules/services/*` — single-purpose,
+  single-host
  feature modules (e.g. `docker/enable-service.nix`,
  `services/zfs/enable-service.nix`). Grep `modules/build-types/*.nix` for
  each build type's `imports` list to see which modules apply where.
@@ -10,11 +10,11 @@ pieces composed in `flake.nix`:

 - **Platforms** (what it runs on): `linode`, `proxmox`, `lxc`
 - **Build types** (what it's for): `minimal`, `nix-cache`, `server`, `docker`,
-  `gui`, `pxe-boot`, `tailscale-exit-node`
+  `gui`, `pxe-boot`, `tailscale-exit-node`, `tor-relay`

 Not every combination exists — `pxe-boot` has no `linode` variant, since
-PXE/DHCP/TFTP need LAN L2 adjacency that a Linode VPS doesn't have. The full
-list:
+PXE/DHCP/TFTP need LAN L2 adjacency that a Linode VPS doesn't have, and
+`tor-relay` currently only exists as `lxc-tor-relay`. The full list:

 | Target | Purpose |
 | --- | --- |
@@ -27,13 +27,14 @@ list:
 | `linode-gui` / `proxmox-gui` / `lxc-gui` | Cinnamon desktop workstation — previously the flat `nixos` target |
 | `proxmox-pxe-boot` / `lxc-pxe-boot` | HTTP/iPXE boot asset host — previously the flat `pxe-boot` target |
 | `linode-tailscale-exit-node` / `proxmox-tailscale-exit-node` / `lxc-tailscale-exit-node` | Tailscale exit node |
+| `lxc-tor-relay` | Tor middle relay |

 Which variant of a given buildtype is actually deployed isn't tracked
 anywhere in this repo — that's live infrastructure state, not something a
 committed file can keep accurate, and it changes independently of the code.
 Check the Proxmox node itself, or `/etc/flake-target` on a running host (see
 below), if you need to know what's really out there right now.
-`scripts/create-proxmox-resource.sh`'s duplicate-host guard works the same
+`scripts/proxmox/create-proxmox-resource.sh`'s duplicate-host guard works the same
 way: it checks the Proxmox node directly rather than any file here.

 Each buildtype's `hosts/<name>/host.nix` carries the per-machine identity
@@ -113,10 +114,11 @@ Three different paths depending on target, none of them involving a manual
  disk image and attached to a new VM with no install step — see
  `docs/proxmox-images.md`.

-`scripts/create-proxmox-resource.sh --type lxc|vm --host <name>` automates
-either of the last two end to end (build, host-key registration, upload,
-`pct create`/`qm create`), with `--dry-run` and a guard against duplicating
-an already-deployed host's identity. See its `--help`.
+`scripts/proxmox/create-proxmox-resource.sh --type lxc|vm --host <name>` automates
+either of the last two end to end (host-key registration, building the
+image directly on the Proxmox node itself, `pct create`/`qm create`), with
+`--dry-run` and a guard against duplicating an already-deployed host's
+identity. See its `--help`.

 ## Security Notes

@@ -19,7 +19,7 @@ see "LXC hosts" immediately below for why those are different.**
 ## LXC hosts

 `lxc-*` targets (`lxc-minimal`, `lxc-nix-cache`, `lxc-server`, `lxc-docker`,
-`lxc-gui`, `lxc-pxe-boot`) are **not** installed via `auto-install.sh` — the
+`lxc-gui`, `lxc-pxe-boot`, `lxc-tailscale-exit-node`, `lxc-tor-relay`) are **not** installed via `auto-install.sh` — the
 interactive menu deliberately excludes them. Don't try to select one there;
 `nixos-install` would bind-mount `/` onto `/mnt` (LXC containers have no raw
 disk to partition) and then refuse to touch the filesystem it's currently
@@ -73,9 +73,9 @@ booting one:

 First boot runs `boot.postBootCommands` (registers the Nix store DB and
 system profile) — there's no separate activation step to run yourself.
-`scripts/create-proxmox-resource.sh --type lxc --host <name>` automates all
-of this (build, host-key handling, upload, `pct create` with the flags
-above) — see its `--help`.
+`scripts/proxmox/create-proxmox-resource.sh --type lxc --host <name>` automates all
+of this (host-key handling, building the tarball directly on the Proxmox
+node itself, `pct create` with the flags above) — see its `--help`.

 Host keys still need pre-seeding the same way as any other host — the
 sops-nix activation-vs-first-boot race is identical regardless of how the
@@ -102,7 +102,7 @@ groups required, got 0`, and *every* secret (including this host's own
 login) permanently fails to decrypt, silently — no error in the boot log
 at all, since the activation step that would install secrets only runs on
 a from-scratch first activation and skips silently once `/run/current-system`
-already exists. `scripts/create-proxmox-resource.sh` always builds with
+already exists. `scripts/proxmox/create-proxmox-resource.sh` always builds with
 `NIXOS_HOST_KEYS_DIR` set for this reason.

 ## Layout
@@ -116,10 +116,10 @@ already exists. `scripts/create-proxmox-resource.sh` always builds with
  `docs/pxe-boot.md`).
 - `modules/installer/host-keys.nix` — optionally bakes pre-generated SSH
  host keys into the image; see "Host keys" below.
- `scripts/sync-host-keys.sh` — admin-workstation tool that generates,
+- `scripts/secrets/sync-host-keys.sh` — admin-workstation tool that generates,
  registers, and (via `--remove`/`--regenerate-all-keys`) retires host
  keys; see "Creating a New Machine" below.
- `scripts/prepare-host-key.sh` — narrower predecessor: generates a single
+- `scripts/secrets/prepare-host-key.sh` — narrower predecessor: generates a single
  key by an arbitrary name without touching `.sops.yaml`. Still useful for
  pre-generating a key *before* its flake target exists (`sync-host-keys.sh`
  can only act on targets `nixosConfigurations` already has); otherwise
@@ -238,7 +238,7 @@ GitHub token behind sops-nix for all of them).
 2. **On your admin workstation, generate and register its host key:**

   ```sh
-   ./scripts/sync-host-keys.sh <flake-target>
+   ./scripts/secrets/sync-host-keys.sh <flake-target>
   ```

   This generates `host-keys/<flake-target>_ssh_host_ed25519_key(.pub)`,
@@ -250,7 +250,7 @@ GitHub token behind sops-nix for all of them).

   Doing this for every host that needs one at once — after adding several
   new targets, or just to catch up any that were missed — is
-   `./scripts/sync-host-keys.sh --all`. See `scripts/sync-host-keys.sh --help`
+   `./scripts/secrets/sync-host-keys.sh --all`. See `scripts/secrets/sync-host-keys.sh --help`
   for its other modes (`--remove`, `--regenerate-all-keys`).

 3. **Commit and push.** The flake build the installer uses has to see the
@@ -46,18 +46,26 @@ the new key up automatically on next activation — no more manual

 ## Remote builder SSH keys

-On each client, install the private key used to authenticate as `nixremote`:
+Each client authenticates as `nixremote` using its **own default root SSH
+identity** (`/root/.ssh/id_ed25519`) — not a separately-named or shared
+keypair. If a client doesn't have one yet:

 ```bash
-sudo install -d -m 0700 /root/.ssh
-sudo install -m 0600 ./nixremote /root/.ssh/nixremote
-sudo ssh -i /root/.ssh/nixremote nixremote@nix-cache nix-store --version
+sudo ssh-keygen -t ed25519 -N '' -f /root/.ssh/id_ed25519
 ```

-On `nix-cache`, install the matching public key used by `nixremote` authorized keys.
+Then add its `.pub` contents as a new entry in `vars.remoteBuilderAuthorizedKeys`
+(`variables.nix`) and rebuild `nix-cache` to pick it up (that list is
+declarative — an imperative `ssh-copy-id nixremote@nix-cache` won't stick;
+it gets overwritten on every rebuild). Verify with:

-The committed `nixremote` authorized keys are public SSH keys only. Keep the
-matching private keys on client hosts and out of the repository.
+```bash
+sudo ssh -i /root/.ssh/id_ed25519 nixremote@nix-cache nix-store --version
+```
+
+The committed `remoteBuilderAuthorizedKeys` entries are public SSH keys
+only. Keep the matching private keys on client hosts and out of the
+repository.

 nix-cache's own SSH *host* key is trusted declaratively via
 `programs.ssh.knownHosts` in `modules/nix-cache/remote-builder-client.nix`,
@@ -76,8 +84,8 @@ After deployment:
 curl http://nix-cache/nix-cache-info
 nix store ping --store http://nix-cache
 nix show-config | grep -E 'substituters|trusted-public-keys|builders-use-substitutes'
-sudo ssh -i /root/.ssh/nixremote nixremote@nix-cache nix-store --version
-nix build nixpkgs#hello --builders 'ssh://nixremote@nix-cache x86_64-linux /root/.ssh/nixremote 4 2 big-parallel,kvm,nixos-test,benchmark' -L
+sudo ssh -i /root/.ssh/id_ed25519 nixremote@nix-cache nix-store --version
+nix build nixpkgs#hello --builders 'ssh://nixremote@nix-cache x86_64-linux /root/.ssh/id_ed25519 4 2 big-parallel,kvm,nixos-test,benchmark' -L
 nix path-info -r nixpkgs#hello
 curl -I "http://nix-cache/$(basename "$(nix path-info nixpkgs#hello)").narinfo"
 ```
@@ -7,11 +7,13 @@ config (`modules/disko/proxmox.nix`) already used to format a real disk on
 install, so there's nothing host-specific to write; it's available for every
 `proxmox-*` target automatically.

-`scripts/create-proxmox-resource.sh --type vm --host <name>` automates the
+`scripts/proxmox/create-proxmox-resource.sh --type vm --host <name>` automates the
 whole walkthrough below (and the equivalent LXC one) end to end, including
-host-key handling and upload — see its `--help`. The steps here are what it
-runs under the hood, useful for doing any of it by hand or understanding
-what it does before you trust it against real infrastructure.
+host-key handling and building the image directly on the Proxmox node
+itself (no local build, no image transfer) — see its `--help`. The steps
+here are what it runs under the hood, useful for doing any of it by hand
+or understanding what it does before you trust it against real
+infrastructure.

 ## Building

@@ -49,7 +51,7 @@ sudo ./result \
  --build-memory 2048
 ```

-Generate the key first with `scripts/sync-host-keys.sh <hostname>`, same
+Generate the key first with `scripts/secrets/sync-host-keys.sh <hostname>`, same
 as any other host — see `docs/auto-installer.md` for the full walkthrough
 (it registers the new key in `.sops.yaml` and re-encrypts the affected
 `secrets/*.yaml` files too, no manual editing needed).
@@ -1,143 +0,0 @@
-# Spec: Refactor Flake Targets into Platform × Build-Type Matrix
-
-## Context
-
-The flake at `~/nixos` currently defines these output targets (flat, ad-hoc naming):
-
- `docker`
- `linode-minimal`
- `nix-cache`
- `nix-minimal`
- `nixos`
- `server`
- `pxe-boot`
-
-Some already follow a `platform-buildtype` convention (`linode-minimal`), most don't.
-`~/nix-auto-installer` is a related repo and should be checked for any coupling to
-these target names (scripts, docs, CI, or install automation that reference them by
-name) before renaming anything.
-
-## Goal
-
-Restructure the flake so targets are generated from two orthogonal concepts:
-
-**Build types** (what the system is for):
- `minimal`
- `nix-cache`
- `server`
- `docker`
- `pxe-boot`
- `gui`
-
-**Platforms** (what it's deployed on):
- `linode` (Linode VM)
- `proxmox` (Proxmox VM)
- `lxc` (Proxmox LXC container)
-
-Final targets should be named consistently as `<platform>-<buildtype>`, e.g.:
-
-```
-linode-minimal    proxmox-minimal    lxc-minimal
-linode-nix-cache  proxmox-nix-cache  lxc-nix-cache
-linode-server     proxmox-server     lxc-server
-linode-docker     proxmox-docker     lxc-docker
-linode-pxe-boot   proxmox-pxe-boot   lxc-pxe-boot
-linode-gui        proxmox-gui        lxc-gui
-```
-
-That's the full matrix (18 targets) if every build type applies to every platform.
-See **Open Questions** below — some combinations may not make sense and should be
-confirmed with me before being built out, not silently included or dropped.
-
-## Migration mapping (old → new)
-
-| Old target        | New target                                          | Notes |
-|--------------------|------------------------------------------------------|-------|
-| `linode-minimal`   | `linode-minimal`                                      | Already correct, keep as-is |
-| `nix-minimal`      | likely `proxmox-minimal` or a platform-less base module | Ambiguous — see Open Questions |
-| `nix-cache`        | base module consumed by `linode-nix-cache`, `proxmox-nix-cache`, `lxc-nix-cache` | Currently platform-less; needs to become a build-type module, not a standalone target |
-| `server`           | base module consumed by `linode-server`, `proxmox-server`, `lxc-server` | Same as above |
-| `docker`           | base module consumed by `linode-docker`, `proxmox-docker`, `lxc-docker` | Confirm docker actually makes sense as an LXC/VM guest build vs. a standalone container image — see Open Questions |
-| `pxe-boot`         | TBD — may stay a single target rather than a per-platform one | See Open Questions |
-| `nixos`            | TBD — unclear what this maps to in the new scheme | See Open Questions |
-
-## Open Questions (Claude Code: raise these with me before implementing, don't guess)
-
-1. **`nixos` target** — what is this currently used for (bare metal install, dev
-   shell, template)? It doesn't obviously map to any of the six build types.
-2. **`nix-minimal` vs `linode-minimal`** — are these two different things, or is
-   `nix-minimal` a leftover/duplicate?
-3. **`pxe-boot` and `gui` across all three platforms** — does PXE boot make sense
-   for an LXC container or a cloud VM (Linode), or is it inherently bare-metal/
-   network-boot only and should remain a single non-platform target? Does `gui`
-   make sense inside an LXC container?
-4. **`docker` as a build type** — is this "a NixOS host configured to run Docker"
-   (which would sensibly have linode/proxmox/lxc variants), or "a Docker container
-   image built by the flake" (which wouldn't take a platform prefix at all, since
-   it doesn't run on Linode/Proxmox/LXC as a guest OS)? These are structurally
-   different and change how it should be wired in.
-5. Confirm whether all 18 combinations should actually exist, or whether this is
-   meant to produce only the combinations that are genuinely useful (e.g. maybe no
-   one needs `lxc-pxe-boot`).
-
-## Implementation approach
-
-1. **Inventory first.** Read the current `flake.nix` and any `nixosConfigurations`/
-   `modules` structure. Map every existing target to what module(s) it actually
-   pulls in. Don't assume — confirm against the real file contents.
-2. **Separate build-type and platform into their own module directories**, e.g.:
-   ```
-   modules/build-types/minimal.nix
-   modules/build-types/nix-cache.nix
-   modules/build-types/server.nix
-   modules/build-types/docker.nix
-   modules/build-types/pxe-boot.nix
-   modules/build-types/gui.nix
-
-   modules/platforms/linode.nix
-   modules/platforms/proxmox.nix
-   modules/platforms/lxc.nix
-   ```
-   Build-type modules should contain only what makes a system "minimal" vs
-   "server" vs "gui", etc. Platform modules should contain only what's specific
-   to running as a Linode VM vs Proxmox VM vs LXC container (virtualisation
-   guest tools, boot method, filesystem/image format, LXC-specific constraints
-   like no kernel modules, etc).
-3. **Generate the target matrix programmatically** in `flake.nix` rather than
-   hand-writing 18 near-identical `nixosConfigurations` entries — e.g. a small
-   function that takes a platform name and build-type name, composes the two
-   modules plus any shared base module, and produces the named output. This
-   keeps future build types/platforms a one-line addition rather than a copy-paste
-   job.
-4. **Only build combinations we've confirmed make sense** (see Open Questions) —
-   don't emit all 18 by default if some are structurally invalid.
-5. **Preserve existing working configs during the transition.** Don't delete the
-   old target names until their replacements build successfully — rename/alias
-   at the end, not the start, so there's no window where the flake is broken.
-
-## Verification
-
-For every new target produced:
-```bash
-nix flake check
-nix build .#nixosConfigurations.<target>.config.system.build.toplevel
-```
-Confirm each builds without evaluation errors before considering it done. If a
-target fails to build, report which one and why rather than silently skipping it.
-
-## Deliverables
-
- Refactored `flake.nix` using the composed module + generated-matrix approach.
- New `modules/build-types/*.nix` and `modules/platforms/*.nix` files.
- Old flat target names removed only after their replacements are verified.
- A short `README.md` (or section in existing docs) listing the final target
-  names and what each one is for.
- A summary at the end of what changed, what was removed, and any of the Open
-  Questions above that got resolved differently than expected.
-
-## Out of scope
-
- Don't touch `~/nix-auto-installer` contents beyond checking it for references
-  to the old target names — if changes there are needed, flag them, don't make
-  them without confirming.
- Don't add new build types or platforms beyond the ones listed here.
@@ -98,6 +98,8 @@
        linode-tailscale-exit-node = mkTarget { platform = "linode"; buildType = "tailscale-exit-node"; hostPath = ./hosts/tailscale-exit-node/host.nix; };
        proxmox-tailscale-exit-node = mkTarget { platform = "proxmox"; buildType = "tailscale-exit-node"; hostPath = ./hosts/tailscale-exit-node/host.nix; };
        lxc-tailscale-exit-node = mkTarget { platform = "lxc"; buildType = "tailscale-exit-node"; hostPath = ./hosts/tailscale-exit-node/host.nix; };
+
+        lxc-tor-relay = mkTarget { platform = "lxc"; buildType = "tor-relay"; hostPath = ./hosts/tor-relay/host.nix; };
      };

      # Auto-install environments (migrated from the former nix-auto-installer
@@ -0,0 +1,12 @@
+_:
+
+{
+  networking.hostName = "tor-relay";
+
+  # No networking.hostId: only ZFS-touching hosts (server, docker) need one
+  # for pool-import safety, and this host does neither.
+
+  # A genuinely new host (not a pre-refactor carry-over), so it tracks the
+  # flake's current nixpkgs release rather than being pinned to an older one.
+  system.stateVersion = "26.05";
+}
@@ -0,0 +1,7 @@
+{ ... }:
+
+{
+  imports = [
+    ../tor/enable-relay.nix
+  ];
+}
@@ -1,5 +1,15 @@
 { config, lib, pkgs, vars, ... }:

+let
+  # `x-systemd.automount` never works inside a Linux container (LXC
+  # included, regardless of privilege) -- confirmed live on lxc-docker:
+  # systemd logs "Starting of <unit>.automount unsupported" for every
+  # share and never mounts them. Mount eagerly there instead, with
+  # `nofail` so a boot with the NFS server unreachable doesn't hang
+  # (the VM platforms rely on automount itself to get that same
+  # non-blocking behavior, so they don't need `nofail` too).
+  automountOpts = if config.boot.isContainer then [ "nofail" ] else [ "x-systemd.automount" ];
+in
 {
  fileSystems = {
    ${vars.nfsShares.dockerConfig.mountpoint} = {
@@ -9,9 +19,8 @@
      options = [
        "nfsvers=4.2"
        "_netdev"
-        "x-systemd.automount"
        "noatime"
-      ];
+      ] ++ automountOpts;
    };

    ${vars.nfsShares.dockerDatabases.mountpoint} = {
@@ -21,9 +30,8 @@
      options = [
        "nfsvers=4.2"
        "_netdev"
-        "x-systemd.automount"
        "noatime"
-      ];
+      ] ++ automountOpts;
    };

    ${vars.nfsShares.dockerVolumes.mountpoint} = {
@@ -33,9 +41,8 @@
      options = [
        "nfsvers=4.2"
        "_netdev"
-        "x-systemd.automount"
        "noatime"
-      ];
+      ] ++ automountOpts;
    };

    ${vars.nfsShares.nextcloudData.mountpoint} = {
@@ -45,9 +52,8 @@
      options = [
        "nfsvers=4.2"
        "_netdev"
-        "x-systemd.automount"
        "noatime"
-      ];
+      ] ++ automountOpts;
    };

    ${vars.nfsShares.raspiVolumes.mountpoint} = {
@@ -57,9 +63,8 @@
      options = [
        "nfsvers=4.2"
        "_netdev"
-        "x-systemd.automount"
        "noatime"
-      ];
+      ] ++ automountOpts;
    };
  };
 }
@@ -130,7 +130,7 @@
        # at *activation* time, which runs before systemd would otherwise
        # generate one on first boot. Without pre-seeding it here, secrets
        # (including the login password) fail to decrypt on first boot.
-        # Generate the key with scripts/prepare-host-key.sh first.
+        # Generate the key with scripts/secrets/prepare-host-key.sh first.
        #
        # Two places a key can come from, checked in order:
        #   /etc/host-keys  — baked into this image at build time (see
@@ -150,7 +150,7 @@
        else
            echo "WARNING: no SSH host key found for ''${choice} (checked /etc/host-keys and /root/host-keys)"
            echo "sops-nix secrets (including the login password) will NOT decrypt on first boot."
-            echo "Run scripts/prepare-host-key.sh for host ''${choice} on your admin workstation first,"
+            echo "Run scripts/secrets/prepare-host-key.sh for host ''${choice} on your admin workstation first,"
            echo "then either rebuild this image with NIXOS_HOST_KEYS_DIR set, or scp the result to"
            echo "/root/host-keys/ on this machine."
            read -rp "Continue without a pre-seeded key anyway? (y/N): " skip_key
@@ -1,10 +1,14 @@
 { pkgs, vars, ... }:

 {
-  # Install the remote builder key on each client host (do not commit private keys):
-  #   sudo install -d -m 0700 /root/.ssh
-  #   sudo install -m 0600 ./nixremote /root/.ssh/nixremote
-  #   sudo ssh -i /root/.ssh/nixremote nixremote@nix-cache nix-store --version
+  # Authenticate as nixremote using the client host's own default root SSH
+  # identity (/root/.ssh/id_ed25519) rather than a separately-named key --
+  # matches vars.remoteBuilderAuthorizedKeys, which already authorizes
+  # each host's own default key (one entry per host, not a shared
+  # dedicated keypair). If this host doesn't have one yet:
+  #   sudo -u root ssh-keygen -t ed25519 -N '' -f /root/.ssh/id_ed25519
+  #   # then add its .pub to vars.remoteBuilderAuthorizedKeys and rebuild nix-cache
+  #   sudo ssh -i /root/.ssh/id_ed25519 nixremote@nix-cache nix-store --version
  # Trust nix-cache's SSH host key declaratively so the nix-daemon (root)
  # can connect the first time without a manual ssh-keyscan/known_hosts
  # step on every new client.
@@ -20,7 +24,7 @@
      {
        hostName = vars.nixCacheHost;
        sshUser = vars.remoteBuilderUser;
-        sshKey = "/root/.ssh/${vars.remoteBuilderUser}";
+        sshKey = "/root/.ssh/id_ed25519";
        inherit (pkgs.stdenv.hostPlatform) system;
        maxJobs = 4;
        speedFactor = 2;
@@ -14,7 +14,7 @@ let
  # Without this, config.system.build.tarball's built-in system just
  # generates a fresh host key at first boot like any other host would --
  # but sops-nix derives its decryption key from *this* file, and
-  # .sops.yaml only trusts whatever key scripts/sync-host-keys.sh already
+  # .sops.yaml only trusts whatever key scripts/secrets/sync-host-keys.sh already
  # registered for this exact target name. A freshly-generated key can
  # never match that, so every secret (including this host's own login)
  # permanently fails to decrypt. Confirmed live: sops-install-secrets
@@ -26,7 +26,7 @@ let
  hostKeysDir = /. + hostKeysDirStr;

  # flakeTarget ("${platform}-${buildType}") comes in via specialArgs from
-  # flake.nix's mkTarget -- exactly the name scripts/sync-host-keys.sh
+  # flake.nix's mkTarget -- exactly the name scripts/secrets/sync-host-keys.sh
  # registers keys under. Deliberately not read back from
  # config.environment.etc."flake-target" (which is set to the same value)
  # -- this module also *contributes* to environment.etc below, and a
@@ -1,4 +1,4 @@
-{ vars, ... }:
+{ config, lib, vars, ... }:

 {
  fileSystems.${vars.raspiMountpoint} = {
@@ -9,6 +9,15 @@
      "_netdev"
      "noatime"

+      # Explicitly use NFSv4.2 if supported
+      "nfsvers=4.2"
+    ] ++ lib.optionals (!config.boot.isContainer) [
+      # `x-systemd.automount` never works inside a Linux container (LXC
+      # included) -- confirmed live on lxc-docker: systemd logs "Starting
+      # of <unit>.automount unsupported" and never mounts it. `nofail`
+      # above already keeps boot non-blocking there, so plain eager
+      # mounting is fine.
+
      # Don't mount until first access
      "x-systemd.automount"

@@ -17,9 +26,6 @@

      # Give the Pi/Tailscale a little time to appear
      "x-systemd.device-timeout=10s"
-
-      # Explicitly use NFSv4.2 if supported
-      "nfsvers=4.2"
    ];
  };

@@ -1,8 +1,16 @@
 _:

 {
+  imports = [ ./enable-service.nix ];
+
  services.tailscale = {
-    enable = true;
+    # Enables the sysctl forwarding settings exit nodes/subnet routers need;
+    # without this, --advertise-exit-node has no effect.
+    useRoutingFeatures = "server";
+
+    # Lets peers reach this node directly over the tailscale UDP port
+    # instead of relaying through DERP.
+    openFirewall = true;

    # extraSetFlags (tailscale set, via the always-on tailscaled-set
    # service), not extraUpFlags -- extraUpFlags is only ever applied by
@@ -0,0 +1,35 @@
+{ pkgs, vars, ... }:
+
+{
+  services.tor = {
+    enable = true;
+
+    # Opens settings.ORPort (and DirPort, unset here) in the firewall —
+    # see the nixpkgs tor module's own networking.firewall.mkIf block.
+    openFirewall = true;
+
+    relay = {
+      enable = true;
+      # Plain middle/guard relay, not "exit" — relays onion traffic between
+      # other Tor nodes without ever making requests to the public internet
+      # on a user's behalf, avoiding the abuse complaints and legal exposure
+      # an exit node invites.
+      role = "relay";
+    };
+
+    settings.ORPort = vars.ports.torRelayOrPort;
+
+    # Unix control socket at /run/tor/control (GroupWritable, group "tor")
+    # -- what nyx below actually monitors the relay through. Nyx's own
+    # default control-socket path (/var/run/tor/control) resolves to the
+    # same place, so no extra nyx config is needed.
+    controlSocket.enable = true;
+  };
+
+  # Lets the primary user's shell session read/write the control socket
+  # above without being root -- otherwise nyx fails to authenticate against
+  # it at all.
+  users.users.${vars.primaryUser}.extraGroups = [ "tor" ];
+
+  environment.systemPackages = [ pkgs.nyx ];
+}
@@ -1,134 +0,0 @@
-# Spec: Remove Sensitive Information from NixOS Flake
-
-## Goal
-
-Every secret currently readable in plaintext anywhere in this repo (working tree *and* git history) gets removed, replaced with `sops-nix`-managed encrypted references, and rotated. When this is done, the repo should be safe to make public without exposing anything about the systems it configures.
-
-Treat this as three sequential milestones. Do not start git history rewriting (Milestone 3) until Milestones 1 and 2 are fully verified and the flake still builds. This should be its own branch (`refactor/secrets`) until fully verified, then merged.
-
---
-
-## Milestone 1 — Audit
-
-Before touching anything, produce a complete inventory. Do not guess at scope — grep the whole tree and the whole history.
-
-1. Run a secret scanner across the working tree and full history. Use both, since they catch different things:
-   - `gitleaks detect --source . -v --log-opts="--all"` (scans history too)
-   - `trufflehog git file://. --since-commit=$(git rev-list --max-parents=0 HEAD) --only-verified=false`
-   If neither is installed, add them via a temporary `nix-shell -p gitleaks trufflehog` — don't install anything globally on the host.
-
-2. Manually grep for the categories below, since scanners miss config-specific patterns:
-   - `hashedPassword`, `password`, `initialPassword`, `initialHashedPassword` in any `users.users.*` block
-   - `age.secrets`, `sops.secrets` (if any partial secrets work already exists — check for it)
-   - PSK / `preSharedKey`, `privateKeyFile` inline values (vs. file references) for WireGuard
-   - `authKey`, `apiToken`, `api_key`, `token =`, `secret =` in service modules (Tailscale, Cloudflare, backup tools, etc.)
-   - SSH private key material: search for `BEGIN OPENSSH PRIVATE KEY` / `BEGIN RSA PRIVATE KEY` literals
-   - TLS cert/key pairs committed under e.g. `secrets/`, `certs/`, `pki/`
-   - Real name, personal email, home address, or anything in comments/hostnames that maps a machine to your physical identity or network layout (e.g. hostnames like `wayne-desktop`, static LAN IPs, ISP-identifying info)
-   - `.env` files, `secrets.nix`, `secrets.yaml`, or any file that looks like it was meant to be gitignored but wasn't
-
-3. Produce `secrets-inventory.md` (temporary, delete before finishing) listing: file path, line, secret type, and which host/service it belongs to. This becomes the checklist for Milestone 2 — every row must be either migrated to sops or deleted, with nothing left unaccounted for.
-
---
-
-## Milestone 2 — Migrate to sops-nix
-
-### 2.1 Set up sops-nix
-
-1. Add the flake input:
-   ```nix
-   sops-nix.url = "github:Mic92/sops-nix";
-   sops-nix.inputs.nixpkgs.follows = "nixpkgs";
-   ```
-2. Import `sops-nix.nixosModules.sops` into each host's module list (or into a shared `common.nix` if all hosts use it).
-3. Generate an age keypair **per host** (not one shared key for everything — a compromised host shouldn't decrypt every other host's secrets):
-   ```
-   nix-shell -p age --run "age-keygen -o /var/lib/sops-nix/key.txt"
-   ```
-   Print the public key (`age-keygen -y`) for each host — you'll need it for `.sops.yaml`.
-4. Also generate one age key for yourself (your admin workstation) so you can edit secrets without needing to SSH into a host: store it at `~/.config/sops/age/keys.txt`, back it up somewhere outside this repo (password manager, offline). **If this key is lost, every secret encrypted with it is unrecoverable — losing the age key is equivalent to losing the secrets.**
-5. Create `.sops.yaml` at the repo root defining creation rules: which age public keys can decrypt which secrets files, keyed by path regex, so e.g. `secrets/hostA.yaml` is decryptable by your admin key + hostA's key, `secrets/hostB.yaml` by your admin key + hostB's key.
-
-### 2.2 Migrate each secret category from the inventory
-
-For each row in `secrets-inventory.md`:
-
- **Password hashes**: generate hash with `mkpasswd -m sha-512` (or `bcrypt` if your setup wants that), store under `sops.secrets."<name>/hashedPassword"`, reference via `users.users.<name>.hashedPasswordFile = config.sops.secrets."<name>/hashedPassword".path;`. Do not put the *plaintext* password anywhere, only the hash, and only the hash goes into the encrypted sops file.
- **API tokens / auth keys**: move the raw value into the per-host sops YAML, reference in the module via `config.sops.secrets."<service>/token".path` — most NixOS service modules that take a token also accept a `*File` variant (e.g. `environmentFile`, `tokenFile`); use that instead of passing the value directly.
- **Private keys / certs**: move the PEM/key content wholesale into a sops secret, output as a file with appropriate `sops.secrets.<name>.path`, `owner`, `mode`, `restartUnits` so the depending service (sshd, wireguard, nginx) reloads when the secret changes.
- **Personal/identifying info**: this doesn't belong in sops (it's not "secret," it's just information you don't want public). Replace real names/emails with placeholders or move to a small untracked `local.nix` that's `.gitignore`'d and imported conditionally, with a documented template (`local.nix.example`) committed instead.
-
-### 2.3 Verify before moving on
-
- `nixos-rebuild dry-build --flake .#<host>` succeeds for every host.
- `sudo nixos-rebuild switch --flake .#<host>` on at least one real machine (or a VM) confirms secrets decrypt and services start.
- Confirm decrypted secrets land under `/run/secrets/` (not the Nix store — anything placed in `/nix/store` is world-readable by design, so sops-nix's runtime-only placement is the whole point; double check no module accidentally pulls a secret path into a store-built config file).
- Re-run the grep/scanner sweep from Milestone 1 against the *working tree only* (not history yet) — it should now come back clean.
-
---
-
-## Milestone 3 — Scrub git history
-
-Do this only after Milestone 2 is merged to your main branch and confirmed working, since it rewrites every commit SHA from the point of the earliest offending commit onward.
-
-**This is destructive and irreversible on your local clone. Back up first:**
-```
-cp -r /path/to/nixos-repo /path/to/nixos-repo-backup-$(date +%F)
-```
-
-1. Install `git-filter-repo` (not the older `git filter-branch` / BFG — filter-repo is the currently maintained, faster, safer tool):
-   ```
-   nix-shell -p git-filter-repo
-   ```
-2. Use the `secrets-inventory.md` list to build a list of literal strings/paths to strip. Two approaches, use both:
-   - Path-based: if whole files were secret (e.g. `secrets.nix`, a `.env`, a private key file), remove them entirely from history:
-     ```
-     git filter-repo --path secrets.nix --path .env --invert-paths
-     ```
-   - Value-based: for secrets embedded inline in files you're keeping (not deleting the whole file), use `--replace-text` with a file listing each literal secret string to replace with `***REMOVED***`:
-     ```
-     git filter-repo --replace-text expressions.txt
-     ```
-3. After filtering, verify: run the Milestone 1 scanners again against full history (`--log-opts="--all"`). They must come back clean.
-4. Force-push the rewritten history:
-   ```
-   git push origin --force --all
-   git push origin --force --tags
-   ```
-5. **Every other clone of this repo (other machines, WSL instances, CI) must be deleted and re-cloned fresh** — a `git pull` against rewritten history will not work cleanly and risks resurrecting the old commits. Don't try to reconcile old clones; throw them away and re-clone.
-6. If this repo has ever been pushed to a public host (GitHub, etc.) or a fork/mirror exists, treat every secret that was ever in history as **permanently compromised regardless of the rewrite** — caches, forks, and Wayback-style archives can retain old commits indefinitely. History scrubbing prevents *future* exposure via `git clone`; it does not undo past exposure.
-
---
-
-## Milestone 4 — Rotate everything
-
-Because the secrets were exposed in history (even briefly, even in a private repo), the migration is not complete until every credential in the inventory has been **rotated**, not just re-encrypted. Re-encrypting an already-leaked value protects it going forward but doesn't undo the leak.
-
-For each row in the original inventory:
- Password hashes → change the actual account password, regenerate the hash, update the sops file.
- API tokens/auth keys → revoke the old token in the issuing service's dashboard (Cloudflare, Tailscale, backup provider, etc.) and generate a new one.
- SSH/WireGuard private keys → generate new keypairs, update the corresponding public key wherever it's trusted (authorized_keys, peer configs, etc.), retire the old ones.
- TLS certs → reissue if the private key was exposed.
-
-Keep `secrets-inventory.md` open during this step and check off each row as rotated. Delete the file only once every row is checked off — it should not be committed.
-
---
-
-## Ongoing prevention
-
-Add a pre-commit hook (or a `nix flake check` step) running `gitleaks protect --staged` so a secret can't be committed again by accident. Document in the repo README (briefly) that new secrets go through `sops <file>` to edit, never as plaintext in a tracked file.
-
---
-
-## Definition of done
-
- [ ] Milestone 1 inventory complete and reviewed
- [ ] All hosts have per-host age keys; admin key backed up outside the repo
- [ ] Every inventoried secret migrated to sops-nix, referenced via `*File`/`sops.secrets.*.path`, nothing plaintext in the working tree
- [ ] `nixos-rebuild dry-build` and at least one real `switch` verified per host
- [ ] Working-tree scanner sweep clean
- [ ] History rewritten with `git-filter-repo`, force-pushed, full-history scanner sweep clean
- [ ] All other clones deleted and re-cloned from the rewritten history
- [ ] Every credential in the original inventory rotated (not just re-encrypted)
- [ ] Pre-commit secret scanning hook added
- [ ] `secrets-inventory.md` deleted from the working directory (never committed)
@@ -1,22 +1,14 @@
 #!/usr/bin/env bash
 set -euo pipefail

-export NIX_CONFIG="${NIX_CONFIG:-}
-experimental-features = nix-command flakes
-accept-flake-config = false
-warn-dirty = false
-"
+script_dir="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+# shellcheck source=lib/nix-bootstrap.sh
+source "${script_dir}/lib/nix-bootstrap.sh"
+# shellcheck source=lib/nix-eval.sh
+source "${script_dir}/lib/nix-eval.sh"

 MODE="${1:-validate}"

-ensure_nix_profile() {
-  if [ -f /nix/var/nix/profiles/default/etc/profile.d/nix-daemon.sh ]; then
-    . /nix/var/nix/profiles/default/etc/profile.d/nix-daemon.sh
-  elif [ -f "$HOME/.nix-profile/etc/profile.d/nix.sh" ]; then
-    . "$HOME/.nix-profile/etc/profile.d/nix.sh"
-  fi
-}
-
 ensure_nix_profile

 if ! command -v nix >/dev/null 2>&1; then
@@ -24,8 +16,7 @@ if ! command -v nix >/dev/null 2>&1; then
  exit 127
 fi

-hosts_json="$(nix eval --json --no-use-registries --no-accept-flake-config .#nixosConfigurations --apply builtins.attrNames)"
-hosts="$(echo "$hosts_json" | jq -r '.[]')"
+hosts="$(list_flake_targets .)"

 echo "Hosts:"
 echo "$hosts"
@@ -44,17 +35,31 @@ fi

 echo
 echo "Checking Nix formatting with nixpkgs-fmt..."
-nix run --no-use-registries --no-accept-flake-config github:NixOS/nixpkgs/nixos-25.11#nixpkgs-fmt -- --check .
+nix run "${NIX_EVAL_FLAGS[@]}" github:NixOS/nixpkgs/nixos-25.11#nixpkgs-fmt -- --check .

 echo
 echo "Running statix lint..."
-nix run --no-use-registries --no-accept-flake-config github:NixOS/nixpkgs/nixos-25.11#statix -- check .
+nix run "${NIX_EVAL_FLAGS[@]}" github:NixOS/nixpkgs/nixos-25.11#statix -- check .
+
+echo
+echo "Checking nix-cache host key for drift..."
+if bash "${script_dir}/secrets/sync-nix-cache-host-key.sh" --check; then
+  :
+else
+  drift_status=$?
+  if [[ "$drift_status" -eq 2 ]]; then
+    echo "nix-cache unreachable from here -- skipping host-key drift check."
+  else
+    echo "WARNING: nix-cache's host key has drifted from variables.nix (see above)." >&2
+    echo "  Run 'bash scripts/secrets/sync-nix-cache-host-key.sh' to fix." >&2
+  fi
+fi

 echo
 echo "Evaluating host toplevel derivations..."
 for host in $hosts; do
  echo "==> $host"
-  nix eval --raw --no-use-registries --no-accept-flake-config ".#nixosConfigurations.${host}.config.system.build.toplevel.drvPath"
+  nix eval --raw "${NIX_EVAL_FLAGS[@]}" ".#nixosConfigurations.${host}.config.system.build.toplevel.drvPath"

  # lxc-* hosts deploy via a directly pct-restore-able tarball instead of
  # nixos-install (see docs/auto-installer.md); proxmox-* hosts can
@@ -64,22 +69,21 @@ for host in $hosts; do
  case "$host" in
    lxc-*)
      echo "==> $host (tarball)"
-      nix eval --raw --no-use-registries --no-accept-flake-config ".#nixosConfigurations.${host}.config.system.build.tarball.drvPath"
+      nix eval --raw "${NIX_EVAL_FLAGS[@]}" ".#nixosConfigurations.${host}.config.system.build.tarball.drvPath"
      ;;
    proxmox-*)
      echo "==> $host (diskoImagesScript)"
-      nix eval --raw --no-use-registries --no-accept-flake-config ".#nixosConfigurations.${host}.config.system.build.diskoImagesScript.drvPath"
+      nix eval --raw "${NIX_EVAL_FLAGS[@]}" ".#nixosConfigurations.${host}.config.system.build.diskoImagesScript.drvPath"
      ;;
  esac
 done

 echo
 echo "Evaluating buildable packages..."
-packages_json="$(nix eval --json --no-use-registries --no-accept-flake-config .#packages.x86_64-linux --apply builtins.attrNames)"
-packages="$(echo "$packages_json" | jq -r '.[]')"
+packages="$(nix eval --json "${NIX_EVAL_FLAGS[@]}" .#packages.x86_64-linux --apply builtins.attrNames | jq -r '.[]')"
 for pkg in $packages; do
  echo "==> packages.x86_64-linux.${pkg}"
-  nix eval --raw --no-use-registries --no-accept-flake-config ".#packages.x86_64-linux.${pkg}"
+  nix eval --raw "${NIX_EVAL_FLAGS[@]}" ".#packages.x86_64-linux.${pkg}"
 done

 if [[ "$MODE" == "dry-run" ]]; then
@@ -87,16 +91,16 @@ if [[ "$MODE" == "dry-run" ]]; then
  echo "Running dry-run builds for all hosts. This will not create result symlinks."
  for host in $hosts; do
    echo "==> Dry-run build: $host"
-    nix build --dry-run --no-link --no-use-registries --no-accept-flake-config ".#nixosConfigurations.${host}.config.system.build.toplevel"
+    nix build --dry-run --no-link "${NIX_EVAL_FLAGS[@]}" ".#nixosConfigurations.${host}.config.system.build.toplevel"

    case "$host" in
      lxc-*)
        echo "==> Dry-run build: $host (tarball)"
-        nix build --dry-run --no-link --no-use-registries --no-accept-flake-config ".#nixosConfigurations.${host}.config.system.build.tarball"
+        nix build --dry-run --no-link "${NIX_EVAL_FLAGS[@]}" ".#nixosConfigurations.${host}.config.system.build.tarball"
        ;;
      proxmox-*)
        echo "==> Dry-run build: $host (diskoImagesScript)"
-        nix build --dry-run --no-link --no-use-registries --no-accept-flake-config ".#nixosConfigurations.${host}.config.system.build.diskoImagesScript"
+        nix build --dry-run --no-link "${NIX_EVAL_FLAGS[@]}" ".#nixosConfigurations.${host}.config.system.build.diskoImagesScript"
        ;;
    esac
  done
@@ -105,7 +109,7 @@ if [[ "$MODE" == "dry-run" ]]; then
  echo "Running dry-run builds for all packages."
  for pkg in $packages; do
    echo "==> Dry-run build: packages.x86_64-linux.${pkg}"
-    nix build --dry-run --no-link --no-use-registries --no-accept-flake-config ".#packages.x86_64-linux.${pkg}"
+    nix build --dry-run --no-link "${NIX_EVAL_FLAGS[@]}" ".#packages.x86_64-linux.${pkg}"
  done
 fi

@@ -1,19 +1,11 @@
 #!/usr/bin/env bash
 set -euo pipefail

-export NIX_CONFIG="${NIX_CONFIG:-}
-experimental-features = nix-command flakes
-accept-flake-config = false
-warn-dirty = false
-"
-
-ensure_nix_profile() {
-  if [ -f /nix/var/nix/profiles/default/etc/profile.d/nix-daemon.sh ]; then
-    . /nix/var/nix/profiles/default/etc/profile.d/nix-daemon.sh
-  elif [ -f "$HOME/.nix-profile/etc/profile.d/nix.sh" ]; then
-    . "$HOME/.nix-profile/etc/profile.d/nix.sh"
-  fi
-}
+script_dir="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+# shellcheck source=lib/nix-bootstrap.sh
+source "${script_dir}/lib/nix-bootstrap.sh"
+# shellcheck source=lib/nix-eval.sh
+source "${script_dir}/lib/nix-eval.sh"

 install_nix_if_missing() {
  if command -v nix >/dev/null 2>&1; then
@@ -49,6 +41,17 @@ warn-dirty = false
 build-users-group = nixbld
 EOF

+    # The official installer's single-user root path still shells out to
+    # `sudo` to create /nix even though it already knows it's running as
+    # root -- confirmed live against a sudo-less minimal Debian/Proxmox
+    # node, where it fails with "sudo: not found" and prints this exact
+    # mkdir/chown as the manual fix. Pre-create it so that branch of the
+    # installer is skipped entirely.
+    if [ ! -d /nix ]; then
+      mkdir -m 0755 /nix
+      chown root /nix
+    fi
+
    sh <(curl -L https://nixos.org/nix/install) --no-daemon
  else
    sh <(curl -L https://nixos.org/nix/install) --no-daemon
@@ -79,13 +82,13 @@ if ! command -v jq >/dev/null 2>&1; then
 fi

 echo "Available NixOS hosts:"
-hosts="$(nix eval --json --no-use-registries --no-accept-flake-config .#nixosConfigurations --apply builtins.attrNames | jq -r '.[]')"
+hosts="$(list_flake_targets .)"
 echo "$hosts"

 echo "Evaluating all host toplevel derivations..."
 for host in $hosts; do
  echo "==> Evaluating $host"
-  nix eval --raw --no-use-registries --no-accept-flake-config ".#nixosConfigurations.${host}.config.system.build.toplevel.drvPath"
+  nix eval --raw "${NIX_EVAL_FLAGS[@]}" ".#nixosConfigurations.${host}.config.system.build.toplevel.drvPath"
 done

 echo "Codex setup complete."
@@ -3,10 +3,10 @@
 # second copy of these values in every script:
 #   source "$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)/env.sh"
 # Every variable can still be overridden per-invocation via the
-# environment (e.g. PROXMOX_STORAGE=tank-nvme ./scripts/create-proxmox-resource.sh ...)
+# environment (e.g. PROXMOX_STORAGE=tank-nvme ./scripts/proxmox/create-proxmox-resource.sh ...)
 # since each one only sets a default if unset.

-# SSH-reachable Proxmox node that scripts/create-proxmox-resource.sh runs
+# SSH-reachable Proxmox node that scripts/proxmox/create-proxmox-resource.sh runs
 # pct/qm on. Matches the Proxmox web UI hostname already used in
 # hosts/nixos/home.nix's desktop shortcuts (pve.<homeDomain> from
 # variables.nix) -- change this if that's not actually reachable over SSH,
@@ -14,6 +14,14 @@
 : "${PROXMOX_HOST:=pve.sweet.home}"
 : "${PROXMOX_SSH_USER:=root}"

+# Where this flake repo lives on the Proxmox node itself.
+# scripts/proxmox/create-proxmox-resource.sh builds images directly on the node
+# instead of transferring them over the network -- it clones the repo here
+# (from this checkout's own `origin` remote) the first time it doesn't
+# find it, installing build tooling via scripts/codex-setup.sh, then
+# `git pull`s it before every subsequent build.
+: "${PROXMOX_REMOTE_REPO_DIR:=/root/nixos}"
+
 # Storage pool names -- Proxmox's own stock-install defaults, but this
 # varies a lot by setup (ZFS pool name, custom LVM-thin volume, etc.).
 # Verify with `pvesm status` on the node and correct these if wrong.
@@ -45,11 +53,20 @@
 # crash-loops on a denied `/run/credentials/*` mount every ~3s (visible
 # as garbage on the console) and core services like nsncd fail the same
 # way on userns_create; system.build.tarball never finishes activating.
-: "${PROXMOX_DEFAULT_LXC_FEATURES:=nesting=1,keyctl=1}"
+#
+# mount=nfs;nfs4: without it, AppArmor blanket-denies the `nfs`/
+# `rpc_pipefs` mount syscalls any NFS client share needs -- confirmed
+# live on lxc-docker (which mounts several, see modules/docker/mount-data.nix
+# and modules/raspi/mount-data.nix): `mount: /var/lib/nfs/rpc_pipefs:
+# permission denied`. Harmless to grant on lxc targets that don't mount
+# NFS at all -- it only widens what the container is *allowed* to mount,
+# nothing here forces a mount to happen.
+: "${PROXMOX_DEFAULT_LXC_FEATURES:=nesting=1,keyctl=1,mount=nfs;nfs4}"

 export PROXMOX_HOST PROXMOX_SSH_USER PROXMOX_STORAGE PROXMOX_ISO_STORAGE \
  PROXMOX_BRIDGE PROXMOX_DEFAULT_CORES PROXMOX_DEFAULT_MEMORY_MB \
-  PROXMOX_DEFAULT_LXC_DISK_GB PROXMOX_DEFAULT_LXC_FEATURES
+  PROXMOX_DEFAULT_LXC_DISK_GB PROXMOX_DEFAULT_LXC_FEATURES \
+  PROXMOX_REMOTE_REPO_DIR

 # Matches variables.nix's nixCacheHost -- update both if it ever changes.
 : "${NIX_CACHE_HOST:=nix-cache}"
@@ -0,0 +1,21 @@
+#!/usr/bin/env bash
+# Shared "type X to confirm" prompt for scripts/proxmox/create-proxmox-resource.sh
+# (--modify, and replacing an existing --allow-duplicate-host resource) and
+# scripts/secrets/sync-host-keys.sh (--regenerate-all-keys) -- three destructive
+# confirmations that all work the same way (echo the expected value back
+# exactly), kept in one place so the prompt/comparison logic can't drift.
+# Source alongside env.sh:
+#   source "$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)/lib/confirm.sh"
+#
+# Deliberately does NOT print anything on mismatch or decide exit-vs-return
+# -- callers vary on both (a top-level script exits, a subcommand function
+# returns; wording differs too), so that stays at the call site.
+
+# confirm_typed <expected> <prompt>
+# Prints <prompt> via `read -rp`, then reports (via exit status) whether the
+# typed input matched <expected> exactly.
+confirm_typed() {
+  local expected="$1" prompt="$2" input
+  read -rp "$prompt" input
+  [[ "$input" == "$expected" ]]
+}
@@ -0,0 +1,20 @@
+#!/usr/bin/env bash
+# Shared Nix bootstrap for scripts/codex-setup.sh and
+# scripts/codex-maintenance.sh: the nix.conf settings both need in effect
+# before a single `nix` command runs (flakes enabled, never honor a flake
+# input's own nixConfig, no "dirty tree" warning spam), plus a helper to
+# pull an already-installed Nix's daemon/profile script onto PATH if it
+# isn't there yet. Source this instead of copying it -- see CLAUDE.md.
+export NIX_CONFIG="${NIX_CONFIG:-}
+experimental-features = nix-command flakes
+accept-flake-config = false
+warn-dirty = false
+"
+
+ensure_nix_profile() {
+  if [ -f /nix/var/nix/profiles/default/etc/profile.d/nix-daemon.sh ]; then
+    . /nix/var/nix/profiles/default/etc/profile.d/nix-daemon.sh
+  elif [ -f "$HOME/.nix-profile/etc/profile.d/nix.sh" ]; then
+    . "$HOME/.nix-profile/etc/profile.d/nix.sh"
+  fi
+}
@@ -0,0 +1,36 @@
+#!/usr/bin/env bash
+# Shared flake-introspection helpers for scripts/*.sh. Source alongside
+# env.sh:
+#   source "$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)/lib/nix-eval.sh"
+#
+# NIX_EVAL_FLAGS: --no-use-registries so a call here never resolves through
+# the user's global flake registry (every call targets this repo's own
+# flake, or an explicit github: ref, not a registry alias); --no-accept-flake-config
+# so a flake input's own nixConfig (e.g. a dependency's substituters) is
+# never honored -- matches accept-flake-config = false already set repo-wide
+# (see lib/nix-bootstrap.sh / CLAUDE.md). Reuse this array rather than
+# retyping the two flags at each call site.
+declare -a NIX_EVAL_FLAGS=(--no-use-registries --no-accept-flake-config)
+
+# list_flake_targets <flake_ref>
+# Prints the attribute names under <flake_ref>#nixosConfigurations, one per
+# line, e.g.:
+#   list_flake_targets .            # from inside the repo
+#   list_flake_targets "$repo_root" # from anywhere
+list_flake_targets() {
+  local flake_ref="$1"
+  nix eval --json "${NIX_EVAL_FLAGS[@]}" \
+    "${flake_ref}#nixosConfigurations" --apply builtins.attrNames \
+  | jq -r '.[]'
+}
+
+# flake_target_hostname <flake_ref> <target>
+# Prints one nixosConfigurations target's config.networking.hostName.
+# Empty (not an error under set -e) if the target doesn't exist or the
+# eval otherwise fails -- callers that need to distinguish "empty" from
+# "eval failed" should check $? themselves instead of relying on this.
+flake_target_hostname() {
+  local flake_ref="$1" target="$2"
+  nix eval --raw "${NIX_EVAL_FLAGS[@]}" \
+    "${flake_ref}#nixosConfigurations.${target}.config.networking.hostName" 2>/dev/null
+}
@@ -0,0 +1,52 @@
+#!/usr/bin/env bash
+# Shared sops/age helpers for scripts/secrets/backup-admin-key.sh,
+# scripts/secrets/rotate-admin-key.sh, and scripts/secrets/sync-host-keys.sh -- all three
+# derive an age public key from a private identity file the same way, two
+# of them resolve the same sops/age default key-file path, and two of them
+# run `sops updatekeys` the same way. Kept in one place so they can't drift
+# apart. Source alongside env.sh:
+#   source "$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)/lib/sops-age.sh"
+#
+# Uses NIX_OPTS (an array of extra `nix-shell` options -- see env.sh's
+# nix_extra_opts) if the caller has already set it, same convention as
+# lib/ssh-host-keys.sh. Falls back to no extra options if the caller never
+# sourced env.sh.
+if ! declare -p NIX_OPTS >/dev/null 2>&1; then
+  declare -a NIX_OPTS=()
+fi
+
+# sops/age's own default identity-file resolution order, minus $SOPS_AGE_KEY
+# itself (an inline identity, not a path -- callers that accept it check it
+# separately, before falling back to this).
+: "${DEFAULT_SOPS_AGE_KEY_FILE:=${SOPS_AGE_KEY_FILE:-${XDG_CONFIG_HOME:-$HOME/.config}/sops/age/keys.txt}}"
+
+# age_pubkey_from_identity_file <identity-file>
+# Prints the age public key for a private identity file (age-keygen -y).
+age_pubkey_from_identity_file() {
+  local identity_file="$1"
+  nix-shell "${NIX_OPTS[@]}" -p age --run "age-keygen -y '${identity_file}'"
+}
+
+# sops_yaml_admin_pubkey <sops-yaml-path>
+# Prints .sops.yaml's current &admin age public key, or empty (not an error
+# under set -e) if no such anchor line exists -- callers that need to treat
+# "missing" as fatal check for an empty result themselves.
+sops_yaml_admin_pubkey() {
+  local sops_yaml="$1"
+  grep -E '^  - &admin age1' "$sops_yaml" 2>/dev/null | awk '{print $NF}' || true
+}
+
+# sops_updatekeys <secrets-file> [key-file]
+# Re-encrypts <secrets-file> for .sops.yaml's current recipient set. If
+# <key-file> is given, decrypts with that identity (SOPS_AGE_KEY_FILE)
+# instead of whatever's ambient -- needed when the ambient default key
+# doesn't match yet (e.g. mid-rotation, decrypting with the outgoing key).
+sops_updatekeys() {
+  local secrets_file="$1" key_file="${2:-}"
+  if [[ -n "$key_file" ]]; then
+    SOPS_AGE_KEY_FILE="$key_file" nix-shell "${NIX_OPTS[@]}" -p sops --run \
+      "sops updatekeys --yes '${secrets_file}'"
+  else
+    nix-shell "${NIX_OPTS[@]}" -p sops --run "sops updatekeys --yes '${secrets_file}'"
+  fi
+}
@@ -0,0 +1,30 @@
+#!/usr/bin/env bash
+# Shared SSH-host-key / age-conversion helpers for scripts/secrets/sync-host-keys.sh
+# and scripts/secrets/prepare-host-key.sh -- both generate the same kind of key
+# (ed25519, no passphrase, the sops-nix age-derivation input) and convert it
+# to an age recipient the same way; kept in one place so the two can't
+# drift apart.
+#
+# Uses NIX_OPTS (an array of extra `nix-shell` options -- see env.sh's
+# nix_extra_opts) if the caller has already set it, so a decision to avoid
+# an unreachable nix-cache is reused here instead of probed again. Falls
+# back to no extra options if the caller never sourced env.sh.
+if ! declare -p NIX_OPTS >/dev/null 2>&1; then
+  declare -a NIX_OPTS=()
+fi
+
+# generate_host_ed25519_key <hostname> <keyfile>
+# Writes <keyfile> and <keyfile>.pub. Caller is responsible for refusing to
+# overwrite an existing keyfile -- this always runs ssh-keygen fresh.
+generate_host_ed25519_key() {
+  local hostname="$1" keyfile="$2"
+  nix-shell "${NIX_OPTS[@]}" -p openssh --run \
+    "ssh-keygen -t ed25519 -N '' -C '${hostname}' -f '${keyfile}'" >/dev/null
+}
+
+# ssh_pubkey_to_age <pubkeyfile>
+# Prints the age public key derived from an ed25519 SSH public key file.
+ssh_pubkey_to_age() {
+  local pubkeyfile="$1"
+  nix-shell "${NIX_OPTS[@]}" -p ssh-to-age --run "ssh-to-age -i '${pubkeyfile}'"
+}
@@ -0,0 +1,182 @@
+#!/usr/bin/env bash
+# Points a non-NixOS Debian machine's Nix install at nix-cache: adds it as
+# a substituter (with cache.nixos.org kept as fallback) and, once the
+# remote-builder private key is installed, as a distributed-build machine
+# too.
+#
+# This is the non-NixOS equivalent of modules/nix-cache/client.nix +
+# modules/nix-cache/remote-builder-client.nix -- those two only apply to
+# hosts built from this flake. A plain Debian box with Nix installed
+# (single- or multi-user install, nix-daemon running) has no NixOS module
+# system to pick that config up, so this edits /etc/nix/nix.conf by hand
+# instead. Run this ON the target Debian machine, as root.
+#
+# The values below mirror variables.nix / modules/nix-cache/client.nix in
+# this repo -- update both if nix-cache is ever rebuilt with a new host
+# key or the cache signing key is rotated (see docs/nix-cache.md).
+#
+# REMOTE_BUILDER_KEY defaults to this machine's own default root SSH
+# identity (matches modules/nix-cache/remote-builder-client.nix's
+# convention for real NixOS clients: authenticate as nixremote with the
+# host's own default key, added individually to
+# vars.remoteBuilderAuthorizedKeys, rather than a separately-named or
+# shared keypair) -- generate one with
+# `ssh-keygen -t ed25519 -N '' -f /root/.ssh/id_ed25519` if this machine
+# doesn't have one yet, then add its .pub to vars.remoteBuilderAuthorizedKeys
+# and rebuild nix-cache.
+#
+# Usage:
+#   sudo ./configure-nix-cache-client.sh [--dry-run] [--no-remote-builder] [--no-restart]
+#
+# Env overrides (defaults match variables.nix):
+#   NIX_CACHE_HOST, NIX_CACHE_HOST_KEY, REMOTE_BUILDER_USER, REMOTE_BUILDER_KEY
+
+set -euo pipefail
+
+: "${NIX_CACHE_HOST:=nix-cache}"
+: "${NIX_CACHE_HOST_KEY:=ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIPeWgMsdaiz4axT/deFc1+0B5bN+GX/NOeW9bbQ0c/IT lxc-nix-cache}"
+: "${REMOTE_BUILDER_USER:=nixremote}"
+: "${REMOTE_BUILDER_KEY:=/root/.ssh/id_ed25519}"
+
+CACHE_PUB_KEY="cache.local-1:usoWYanY3Kpq2+kDIS2nhWoLZiRxanmdysdzqCFBHW4="
+FALLBACK_URL="https://cache.nixos.org/"
+FALLBACK_PUB_KEY="cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY="
+
+NIX_CONF="/etc/nix/nix.conf"
+KNOWN_HOSTS="/etc/ssh/ssh_known_hosts"
+MARKER_BEGIN="# BEGIN nix-cache client config (configure-nix-cache-client.sh)"
+MARKER_END="# END nix-cache client config"
+
+dry_run=0
+with_remote_builder=1
+restart_daemon=1
+
+for arg in "$@"; do
+  case "$arg" in
+    --dry-run) dry_run=1 ;;
+    --no-remote-builder) with_remote_builder=0 ;;
+    --no-restart) restart_daemon=0 ;;
+    -h|--help)
+      sed -n '2,20p' "$0"
+      exit 0
+      ;;
+    *)
+      echo "ERROR: unknown argument: $arg" >&2
+      exit 1
+      ;;
+  esac
+done
+
+if [[ "$dry_run" -eq 0 && "$EUID" -ne 0 ]]; then
+  echo "ERROR: must run as root (writes $NIX_CONF and, unless --no-remote-builder, $KNOWN_HOSTS)." >&2
+  exit 1
+fi
+
+if ! command -v nix >/dev/null 2>&1; then
+  echo "ERROR: no 'nix' binary on PATH -- install the Nix package manager first." >&2
+  exit 1
+fi
+
+if [[ ! -f "$NIX_CONF" ]]; then
+  echo "ERROR: $NIX_CONF not found -- expected an existing multi-user Nix install." >&2
+  exit 1
+fi
+
+builder_line=""
+if [[ "$with_remote_builder" -eq 1 ]]; then
+  if [[ -f "$REMOTE_BUILDER_KEY" ]]; then
+    case "$(uname -m)" in
+      x86_64) nix_system="x86_64-linux" ;;
+      aarch64) nix_system="aarch64-linux" ;;
+      *)
+        echo "WARNING: unrecognized architecture '$(uname -m)' -- skipping remote builder, keeping substituter config." >&2
+        with_remote_builder=0
+        ;;
+    esac
+    if [[ "$with_remote_builder" -eq 1 ]]; then
+      builder_line="builders = ssh://${REMOTE_BUILDER_USER}@${NIX_CACHE_HOST} ${nix_system} ${REMOTE_BUILDER_KEY} 4 2 big-parallel,kvm,nixos-test,benchmark"
+    fi
+  else
+    echo "WARNING: $REMOTE_BUILDER_KEY not found -- skipping remote builder config (substituter still configured)." >&2
+    echo "  See docs/nix-cache.md 'Remote builder SSH keys' for how to install it, then re-run this script." >&2
+    with_remote_builder=0
+  fi
+fi
+
+block="$(cat <<EOF
+$MARKER_BEGIN
+extra-substituters = http://${NIX_CACHE_HOST} ${FALLBACK_URL}
+extra-trusted-public-keys = ${CACHE_PUB_KEY} ${FALLBACK_PUB_KEY}
+EOF
+)"
+if [[ "$with_remote_builder" -eq 1 ]]; then
+  block="${block}
+builders-use-substitutes = true
+${builder_line}"
+fi
+block="${block}
+$MARKER_END"
+
+echo "== nix.conf block to install =="
+echo "$block"
+echo "================================"
+
+if [[ "$dry_run" -eq 1 ]]; then
+  echo "(--dry-run: not writing $NIX_CONF)"
+else
+  tmp_conf="$(mktemp)"
+  trap 'rm -f "$tmp_conf"' EXIT
+
+  if grep -qF "$MARKER_BEGIN" "$NIX_CONF"; then
+    awk -v begin="$MARKER_BEGIN" -v end="$MARKER_END" -v block="$block" '
+      $0 == begin { print block; skip = 1; next }
+      $0 == end   { skip = 0; next }
+      skip        { next }
+      { print }
+    ' "$NIX_CONF" > "$tmp_conf"
+  else
+    cp "$NIX_CONF" "$tmp_conf"
+    printf '\n%s\n' "$block" >> "$tmp_conf"
+  fi
+
+  cp "$NIX_CONF" "${NIX_CONF}.bak.$(date +%Y%m%d%H%M%S)"
+  install -m 0644 "$tmp_conf" "$NIX_CONF"
+  echo "Updated $NIX_CONF (backup saved alongside it)."
+fi
+
+if [[ "$with_remote_builder" -eq 1 ]]; then
+  known_hosts_line="${NIX_CACHE_HOST} ${NIX_CACHE_HOST_KEY}"
+  if [[ "$dry_run" -eq 1 ]]; then
+    echo "(--dry-run: would ensure this line is present in $KNOWN_HOSTS)"
+    echo "  $known_hosts_line"
+  else
+    mkdir -p "$(dirname "$KNOWN_HOSTS")"
+    touch "$KNOWN_HOSTS"
+    if ! grep -qF "$known_hosts_line" "$KNOWN_HOSTS" 2>/dev/null; then
+      echo "$known_hosts_line" >> "$KNOWN_HOSTS"
+      echo "Added nix-cache's SSH host key to $KNOWN_HOSTS."
+    fi
+  fi
+fi
+
+if [[ "$dry_run" -eq 0 && "$restart_daemon" -eq 1 ]]; then
+  if command -v systemctl >/dev/null 2>&1 && systemctl is-active --quiet nix-daemon 2>/dev/null; then
+    systemctl restart nix-daemon
+    echo "Restarted nix-daemon to pick up the new config."
+  else
+    echo "nix-daemon not managed by systemd (or not running) -- restart it manually to pick up the new config."
+  fi
+fi
+
+cat <<EOF
+
+Done. Verify with:
+  curl http://${NIX_CACHE_HOST}/nix-cache-info
+  nix show-config | grep -E 'substituters|trusted-public-keys|builders'
+EOF
+if [[ "$with_remote_builder" -eq 1 ]]; then
+  cat <<EOF
+  ssh -i ${REMOTE_BUILDER_KEY} ${REMOTE_BUILDER_USER}@${NIX_CACHE_HOST} nix-store --version
+  nix build nixpkgs#hello -L
+EOF
+fi
@@ -3,31 +3,53 @@
 # existing ones -- the manual workflows in docs/proxmox-images.md (VM) and
 # docs/auto-installer.md's "LXC hosts" section (container), automated.
 #
+# Images are built directly on the Proxmox node (PROXMOX_REMOTE_REPO_DIR /
+# --remote-repo-dir in scripts/env.sh), not on whatever machine runs this
+# script -- there's no multi-gigabyte image to transfer afterward. The first
+# time a node doesn't have that repo path yet, it's bootstrapped: cloned from
+# this checkout's own `origin` remote, then scripts/codex-setup.sh installs
+# the build tooling (Nix, etc.). Every run after that just `git pull`s it and
+# copies over the locally-managed host-keys/ (gitignored, so a git pull
+# alone wouldn't carry it) before building.
+#
 # Usage:
-#   scripts/create-proxmox-resource.sh --type lxc|vm --host <name> [options]
-#   scripts/create-proxmox-resource.sh --type lxc|vm --list
-#   scripts/create-proxmox-resource.sh --modify --vmid <n> [--cores N] [--memory MB] [--grow-disk GB]
+#   scripts/proxmox/create-proxmox-resource.sh --type lxc|vm --host <name> [options]
+#   scripts/proxmox/create-proxmox-resource.sh --type lxc|vm --list
+#   scripts/proxmox/create-proxmox-resource.sh --modify --vmid <n> [--cores N] [--memory MB] [--grow-disk GB]
 #
 # SAFETY:
 #   - The default (create) mode only ever creates a NEW resource -- it
 #     refuses to run if the target VMID already exists on the node, or if
 #     a VM/CT identified as --host already exists under any other VMID
 #     (checked live against the node; --allow-duplicate-host overrides).
+#   - --allow-duplicate-host distinguishes an exact match (same --type
+#     *and* --host, e.g. re-running --type lxc --host docker while an
+#     lxc-docker container already exists -- almost always a redeploy of
+#     the same target to pick up a rebuilt image) from a cross-type match
+#     (a different platform sharing the same host identity, e.g. a
+#     proxmox-docker VM coexisting with lxc-docker). Only the exact match
+#     is destroyed and replaced, after typing the hostname back to
+#     confirm (outside --dry-run) -- a cross-type match is always left
+#     untouched, matching-or-not.
 #   - --modify only ever touches a resource you name explicitly via
 #     --vmid, shows exactly what will change first, and (outside
 #     --dry-run) always requires typing that VMID back to confirm before
 #     anything is sent to the node. There is no bulk/implicit modify.
-#   - Neither mode can start/stop/delete a resource. Not implemented on
-#     purpose -- ask before adding it.
+#   - Outside of --allow-duplicate-host's exact-match replace above,
+#     neither mode can start/stop/delete a resource.
 #
 # See --help for the full option list.
 set -euo pipefail

-repo_root="$(cd "$(dirname "$0")/.." && pwd)"
-# shellcheck source=env.sh
+repo_root="$(cd "$(dirname "$0")/../.." && pwd)"
+# shellcheck source=../env.sh
 source "${repo_root}/scripts/env.sh"
+# shellcheck source=../lib/nix-eval.sh
+source "${repo_root}/scripts/lib/nix-eval.sh"
+# shellcheck source=../lib/confirm.sh
+source "${repo_root}/scripts/lib/confirm.sh"

-sync_keys="${repo_root}/scripts/sync-host-keys.sh"
+sync_keys="${repo_root}/scripts/secrets/sync-host-keys.sh"

 usage() {
  cat <<EOF
@@ -53,16 +75,26 @@ Create mode (default):
                          Refuses to run if this ID already exists.
  --disk-size <GB>           lxc only: rootfs size for \`pct create\`
                              (default: \$PROXMOX_DEFAULT_LXC_DISK_GB, ${PROXMOX_DEFAULT_LXC_DISK_GB}).
-  --image <path>              Use this local image/tarball instead of
-                              checking the node / building one from the flake.
+  --image <path>              Use this local image/tarball (uploaded to the
+                              node via scp) instead of checking the node /
+                              building one there from the flake.
  --force-rebuild                Skip the "does the node already have this
                                  image" check -- always build fresh and
                                  overwrite what's there.
+  --remote-repo-dir <path>       Where this flake repo lives (or gets
+                                  cloned) on the node, and is built from
+                                  (default: \$PROXMOX_REMOTE_REPO_DIR, ${PROXMOX_REMOTE_REPO_DIR}).
  --allow-duplicate-host        Required if a VM/CT identified as --host
                                already exists on the node (checked live via
                                qm/pct, not any file in this repo) --
                                otherwise refused, since it'd share that
-                                host's hostName/hostId.
+                                host's hostName/hostId. An existing resource
+                                of this *same* --type (e.g. re-running --type
+                                lxc --host docker over an existing lxc-docker)
+                                is destroyed and replaced, after confirming --
+                                a different --type sharing the same --host
+                                (e.g. a proxmox-docker VM) is always left
+                                untouched.

 Modify mode (reconfigure an EXISTING resource -- requires --modify):
  --modify                Switch to modify mode.
@@ -114,6 +146,7 @@ storage="$PROXMOX_STORAGE"
 iso_storage="$PROXMOX_ISO_STORAGE"
 bridge="$PROXMOX_BRIDGE"
 node="$PROXMOX_HOST"
+remote_repo_dir="$PROXMOX_REMOTE_REPO_DIR"
 do_list=0
 allow_duplicate_host=0
 force_rebuild=0
@@ -134,6 +167,7 @@ while [[ $# -gt 0 ]]; do
  --iso-storage) iso_storage="$2"; shift 2 ;;
  --bridge) bridge="$2"; shift 2 ;;
  --node) node="$2"; shift 2 ;;
+  --remote-repo-dir) remote_repo_dir="$2"; shift 2 ;;
  --list) do_list=1; shift ;;
  --allow-duplicate-host) allow_duplicate_host=1; shift ;;
  --force-rebuild) force_rebuild=1; shift ;;
@@ -198,8 +232,7 @@ cmd_modify() {
  fi

  echo
-  read -rp "Type the VMID (${vmid}) to confirm these changes: " confirm
-  if [[ "$confirm" != "$vmid" ]]; then
+  if ! confirm_typed "$vmid" "Type the VMID (${vmid}) to confirm these changes: "; then
    echo "Cancelled -- input didn't match ${vmid}."
    exit 1
  fi
@@ -240,15 +273,21 @@ platform_prefix="lxc"
 [[ -z "$memory" ]] && memory="$PROXMOX_DEFAULT_MEMORY_MB"

 # --- discover / resolve the flake target from --host --------------------
+# Emits "<target>\t<hostName>" pairs for every ${platform_prefix}-* flake
+# target -- the one source both --list and the --host lookup below read
+# from, so they can never see a different set of targets from each other.
+targets_for_platform() {
+  local target
+  for target in $(list_flake_targets "$repo_root" 2>/dev/null | grep -- "^${platform_prefix}-"); do
+    printf '%s\t%s\n' "$target" "$(flake_target_hostname "$repo_root" "$target")"
+  done
+}
+
 list_hosts() {
  local target hostname
-  for target in $(nix eval --json --no-use-registries --no-accept-flake-config \
-    "${repo_root}#nixosConfigurations" --apply builtins.attrNames 2>/dev/null \
-    | jq -r --arg p "${platform_prefix}-" '.[] | select(startswith($p))'); do
-    hostname="$(nix eval --raw --no-use-registries --no-accept-flake-config \
-      "${repo_root}#nixosConfigurations.${target}.config.networking.hostName" 2>/dev/null)"
+  while IFS=$'\t' read -r target hostname; do
    printf '  %-12s -> %s\n' "$hostname" "$target"
-  done
+  done < <(targets_for_platform)
 }

 if [[ "$do_list" -eq 1 ]]; then
@@ -263,16 +302,12 @@ if [[ -z "$host" ]]; then
 fi

 flake_target=""
-for target in $(nix eval --json --no-use-registries --no-accept-flake-config \
-  "${repo_root}#nixosConfigurations" --apply builtins.attrNames \
-  | jq -r --arg p "${platform_prefix}-" '.[] | select(startswith($p))'); do
-  hn="$(nix eval --raw --no-use-registries --no-accept-flake-config \
-    "${repo_root}#nixosConfigurations.${target}.config.networking.hostName")"
-  if [[ "$hn" == "$host" ]]; then
+while IFS=$'\t' read -r target hostname; do
+  if [[ "$hostname" == "$host" ]]; then
    flake_target="$target"
    break
  fi
-done
+done < <(targets_for_platform)

 if [[ -z "$flake_target" ]]; then
  echo "ERROR: no ${platform_prefix}-* target has hostName '${host}'." >&2
@@ -300,12 +335,13 @@ fi
 # this script itself always uses unless --name is overridden) -- a guest
 # manually renamed on the node afterwards wouldn't match, but nothing here
 # creates guests that way.
-if [[ "$allow_duplicate_host" -eq 1 ]]; then
-  echo
-  echo "--allow-duplicate-host: skipping the check for an existing '${host}' on ${node}."
-elif [[ "$dry_run" -eq 1 ]]; then
+if [[ "$dry_run" -eq 1 ]]; then
  echo
  echo "[dry-run] would check ${node} for an existing VM/CT identified as '${host}'"
+  if [[ "$allow_duplicate_host" -eq 1 ]]; then
+    echo "[dry-run] --allow-duplicate-host: an existing ${type} named '${host}' would be" \
+      "destroyed and replaced; a different-type match would be left untouched"
+  fi
 else
  echo
  echo "==> Checking ${node} for an existing VM/CT identified as '${host}'..."
@@ -320,6 +356,7 @@ for id in $(pct list 2>/dev/null | awk 'NR>1{print $1}'); do
  n="$(pct config "$id" 2>/dev/null | grep -oP '^hostname:\s*\K\S+' || true)"
  [[ "$n" == "$target" ]] && echo "lxc ${id} ${n}"
 done
+exit 0
 REMOTE_SCRIPT
  )" || ssh_check_status=$?
  if [[ "$ssh_check_status" -ne 0 ]]; then
@@ -329,17 +366,89 @@ REMOTE_SCRIPT
    echo "check entirely)." >&2
    exit 1
  fi
+
+  # Split into "exact" (same resource kind as --type -- i.e. literally this
+  # same host+platform combo already exists, almost always a redeploy of
+  # the same target to test a rebuilt image) vs "cross-type" (a different
+  # platform sharing this host identity, e.g. a stopped proxmox-docker VM
+  # coexisting with an lxc-docker container -- a deliberate, valid setup
+  # this script has never managed and still won't). Read via a herestring
+  # (not a pipe) so the appends below survive outside the loop.
+  this_kind="$type"
+  exact_matches=""
+  cross_matches=""
  if [[ -n "$existing" ]]; then
-    echo "ERROR: '${host}' already exists on ${node}:" >&2
-    echo "$existing" | while read -r kind id n; do
+    while read -r kind id n; do
+      [[ -z "$kind" ]] && continue
+      if [[ "$kind" == "$this_kind" ]]; then
+        exact_matches+="${kind} ${id} ${n}"$'\n'
+      else
+        cross_matches+="${kind} ${id} ${n}"$'\n'
+      fi
+    done <<<"$existing"
+  fi
+
+  if [[ -n "$exact_matches" && "$allow_duplicate_host" -ne 1 ]]; then
+    echo "ERROR: '${host}' already exists on ${node} as this same resource type:" >&2
+    echo "$exact_matches" | while read -r kind id n; do
+      [[ -z "$kind" ]] && continue
+      echo "  - ${kind} VMID ${id} (${n})" >&2
+    done
+    echo "Refusing to create a second ${this_kind} sharing this identity. Pass" >&2
+    echo "--allow-duplicate-host to destroy it and create a fresh one in its place" >&2
+    echo "(after confirming), or use --modify to reconfigure the existing one instead." >&2
+    exit 1
+  fi
+
+  if [[ -n "$cross_matches" && "$allow_duplicate_host" -ne 1 ]]; then
+    echo "ERROR: '${host}' already exists on ${node} as a different resource type:" >&2
+    echo "$cross_matches" | while read -r kind id n; do
+      [[ -z "$kind" ]] && continue
      echo "  - ${kind} VMID ${id} (${n})" >&2
    done
    echo "Refusing to create a second resource sharing this identity. Pass" >&2
    echo "--allow-duplicate-host to create one anyway (it gets its own distinct" >&2
-    echo "sops key and VMID -- the existing resource(s) above are left untouched)," >&2
+    echo "sops key and VMID -- the existing resource above is left untouched)," >&2
    echo "or use --modify to reconfigure the existing one instead." >&2
    exit 1
  fi
+
+  if [[ -n "$cross_matches" ]]; then
+    echo "--allow-duplicate-host: '${host}' also exists on ${node} as a different resource" \
+      "type -- leaving it untouched:"
+    echo "$cross_matches" | while read -r kind id n; do
+      [[ -z "$kind" ]] && continue
+      echo "  - ${kind} VMID ${id} (${n})"
+    done
+  fi
+
+  if [[ -n "$exact_matches" ]]; then
+    echo "--allow-duplicate-host: '${host}' already exists on ${node} as this same resource" \
+      "type -- it will be destroyed and replaced:"
+    echo "$exact_matches" | while read -r kind id n; do
+      [[ -z "$kind" ]] && continue
+      echo "  - ${kind} VMID ${id} (${n})"
+    done
+    echo
+    if ! confirm_typed "$host" "Type the hostname (${host}) to confirm destroying the above and replacing it: "; then
+      echo "Cancelled -- input didn't match ${host}." >&2
+      exit 1
+    fi
+    echo "$exact_matches" | while read -r kind id n; do
+      [[ -z "$kind" ]] && continue
+      echo "==> Destroying ${kind} VMID ${id} (${n})..."
+      if [[ "$kind" == "vm" ]]; then
+        # qm destroy has no --force to stop-then-destroy in one call (pct's
+        # does) -- stop explicitly first if it's running.
+        if ssh "$ssh_target" "qm status ${id}" 2>/dev/null | grep -q running; then
+          ssh "$ssh_target" "qm stop ${id}"
+        fi
+        ssh "$ssh_target" "qm destroy ${id} --purge 1"
+      else
+        ssh "$ssh_target" "pct destroy ${id} --force 1 --purge 1"
+      fi
+    done
+  fi
 fi

 echo "Target: ${flake_target} (host=${host}, type=${type}) -> Proxmox resource '${name}'"
@@ -404,6 +513,99 @@ if [[ "$type" == "lxc" ]]; then
 fi
 remote_path="${remote_dir}/${remote_filename}"

+# --- ensure the flake repo (+ tooling) exists on the node, and is current --
+# Bootstraps once (git clone from this checkout's own `origin`, then
+# scripts/codex-setup.sh installs Nix + friends) if ${remote_repo_dir}
+# doesn't exist yet on the node; otherwise just `git pull`s it, so the image
+# built there reflects what's actually committed and pushed. Only called
+# right before an actual remote build below -- reusing an image already on
+# the node, or an explicit --image, never touch the node's checkout at all.
+ensure_remote_repo() {
+  echo
+  echo "==> Ensuring ${remote_repo_dir} exists and is current on ${node}..."
+  if [[ "$dry_run" -eq 1 ]]; then
+    echo "[dry-run] would ensure ${remote_repo_dir} exists on ${node} (clone if missing, git pull if present), and would verify/bootstrap build tooling there (scripts/codex-setup.sh) if \`nix\` isn't already on PATH -- and if that bootstrap actually ran, would also configure ${node} as a nix-cache client (scripts/proxmox/configure-nix-cache-client.sh)"
+    return
+  fi
+
+  if ssh "$ssh_target" "test -d '${remote_repo_dir}/.git'"; then
+    echo "Repo present -- pulling latest..."
+    ssh "$ssh_target" "cd '${remote_repo_dir}' && git pull --ff-only"
+  else
+    local origin_url
+    origin_url="$(git -C "$repo_root" remote get-url origin 2>/dev/null || true)"
+    if [[ -z "$origin_url" ]]; then
+      echo "ERROR: ${remote_repo_dir} doesn't exist on ${node}, and this checkout has no" >&2
+      echo "'origin' remote to clone from. Set one (git remote add origin <url>) or create" >&2
+      echo "${remote_repo_dir} on ${node} yourself (e.g. git clone), then re-run." >&2
+      exit 1
+    fi
+    echo "Not present -- cloning from ${origin_url}..."
+    ssh "$ssh_target" "git clone '${origin_url}' '${remote_repo_dir}'"
+  fi
+
+  # Trivial check, run every time (not just right after a fresh clone) --
+  # confirmed live: a first bootstrap can clone the repo successfully and
+  # still leave the node without a working `nix` (e.g. the node had no
+  # `sudo`, which the Nix installer's root path depends on -- see the fix
+  # in scripts/codex-setup.sh), and a later run with the repo already
+  # present would otherwise never retry it. Sources
+  # scripts/lib/nix-bootstrap.sh's ensure_nix_profile first -- a
+  # single-user Nix install typically only gets sourced into login shells,
+  # and ssh's non-interactive command execution is neither, so a
+  # freshly-installed `nix` still wouldn't be on PATH here without it.
+  #
+  # Just `nix` today -- the only thing the remote build commands below
+  # actually invoke -- but a list (not a single hardcoded check) so a
+  # future remote step needing another tool can add itself here instead of
+  # growing a parallel check.
+  local remote_required_cmds=(nix)
+  local tooling_check_cmd="cd '${remote_repo_dir}' && . scripts/lib/nix-bootstrap.sh && ensure_nix_profile"
+  local cmd
+  for cmd in "${remote_required_cmds[@]}"; do
+    tooling_check_cmd="${tooling_check_cmd} && command -v ${cmd}"
+  done
+
+  if ssh "$ssh_target" "$tooling_check_cmd" >/dev/null 2>&1; then
+    echo "Build tooling already present on ${node}."
+  else
+    echo "==> Bootstrapping build tooling on ${node} (scripts/codex-setup.sh)..."
+    ssh "$ssh_target" "cd '${remote_repo_dir}' && bash scripts/codex-setup.sh"
+
+    # Only on this first-time bootstrap, not every run -- a node that
+    # already has tooling either already went through this once, or had
+    # it configured some other way, and re-running is harmless but
+    # pointless. Non-fatal: this only makes the node's own builds faster
+    # (substitute from nix-cache instead of building from source) and
+    # offloadable to it as a remote builder -- worth trying, not worth
+    # aborting the image build over if nix-cache happens to be down right
+    # now. Needs ensure_nix_profile first, same as the tooling_check_cmd
+    # above -- ssh's non-interactive command execution won't have picked
+    # up a freshly single-user-installed `nix` otherwise.
+    echo "==> Configuring ${node} as a nix-cache substituter/remote-builder client..."
+    if ! ssh "$ssh_target" "cd '${remote_repo_dir}' && . scripts/lib/nix-bootstrap.sh && ensure_nix_profile && bash scripts/proxmox/configure-nix-cache-client.sh"; then
+      echo "WARNING: configure-nix-cache-client.sh failed on ${node} -- continuing without it (${node} will build from source / against cache.nixos.org only)." >&2
+    fi
+  fi
+}
+
+# --- sync locally-managed host-keys/ to the node ---------------------------
+# Gitignored (see .gitignore), so `git pull` above never carries it -- both
+# build paths need it present as NIXOS_HOST_KEYS_DIR / --pre-format-files
+# input on the node itself now that the build runs there. scp (not rsync,
+# not already a dependency anywhere else in this repo) mirrors how this
+# script already transfers the --image case below.
+sync_remote_host_keys() {
+  echo
+  echo "==> Syncing host-keys/ to ${node}..."
+  if [[ "$dry_run" -eq 1 ]]; then
+    echo "[dry-run] would copy ${repo_root}/host-keys/ to ${ssh_target}:${remote_repo_dir}/host-keys/"
+    return
+  fi
+  ssh "$ssh_target" "mkdir -p '${remote_repo_dir}/host-keys'"
+  scp -pr "${repo_root}/host-keys/." "${ssh_target}:${remote_repo_dir}/host-keys/"
+}
+
 # --- build (or reuse an image already on the node) ------------------------
 echo
 local_image=""
@@ -420,7 +622,7 @@ else
  if [[ "$dry_run" -eq 1 ]]; then
    echo "[dry-run] would check: ssh ${ssh_target} -- test -f ${remote_path}"
  elif ssh "$ssh_target" "test -f '${remote_path}'" 2>/dev/null; then
-    echo "Found it -- reusing, skipping build and upload (use --force-rebuild to override)."
+    echo "Found it -- reusing, skipping build (use --force-rebuild to override)."
    image_already_remote=1
  else
    echo "Not found -- will build."
@@ -428,69 +630,131 @@ else
 fi

 if [[ "$image_already_remote" -eq 0 && -z "$local_image" ]]; then
-  # Mirrors the real build commands' "${NIX_OPTS[@]}" below -- nix_extra_opts
-  # (called earlier, once) has already decided whether nix-cache is in play,
-  # and the dry-run preview needs to reflect that decision instead of always
-  # printing the same command regardless of outcome.
+  ensure_remote_repo
+  sync_remote_host_keys
+
+  # Relayed into the remote build below exactly as decided by the local
+  # nix_extra_opts call earlier in this script -- that decision (whether
+  # nix-cache is reachable) is made once, locally, same as it always has
+  # been; only *where* the resulting "${NIX_OPTS[@]}" gets used as a `nix
+  # build` flag moves to the node. NIX_EXTRA_OPTS is already a %q-quoted
+  # string built for exactly this eval-based reconstruction (see env.sh).
  nix_opts_display=""
  if [[ ${#NIX_OPTS[@]} -gt 0 ]]; then
    printf -v nix_opts_display '%q ' "${NIX_OPTS[@]}"
    nix_opts_display=" ${nix_opts_display% }"
  fi
+
  if [[ "$type" == "lxc" ]]; then
    if [[ "$dry_run" -eq 1 ]]; then
-      echo "[dry-run] would build: NIXOS_HOST_KEYS_DIR=${repo_root}/host-keys nix build --impure \\"
+      echo "[dry-run] would build on ${node}: NIXOS_HOST_KEYS_DIR=\$(pwd)/host-keys nix build --impure \\"
      echo "[dry-run]   --no-use-registries --no-accept-flake-config${nix_opts_display} \\"
      echo "[dry-run]   .#nixosConfigurations.${flake_target}.config.system.build.tarball"
+      echo "[dry-run] would stage the result at ${remote_path}"
      local_image="<built-tarball>"
    else
-      echo "==> Building LXC tarball for ${flake_target}..."
-      NIXOS_HOST_KEYS_DIR="${repo_root}/host-keys" nix build --impure \
+      echo "==> Building LXC tarball for ${flake_target} on ${node}..."
+      # Built as a single already-%q-quoted command string, not separate ssh
+      # argv elements -- ssh joins remote command args with plain spaces and
+      # hands the result to the remote shell to re-split, which would
+      # otherwise scatter NIX_EXTRA_OPTS (itself several space-separated,
+      # %q-quoted tokens) across the wrong positional parameters below.
+      printf -v remote_cmd 'bash -s -- %q %q %q %q %q' \
+        "$remote_repo_dir" "$flake_target" "$remote_dir" "$remote_filename" "$NIX_EXTRA_OPTS"
+      ssh "$ssh_target" "$remote_cmd" <<'REMOTE_SCRIPT'
+set -euo pipefail
+repo_dir="$1"; target="$2"; dest_dir="$3"; dest_name="$4"; nix_extra_opts_str="$5"
+declare -a NIX_OPTS=()
+[[ -n "$nix_extra_opts_str" ]] && eval "NIX_OPTS=(${nix_extra_opts_str})"
+cd "$repo_dir"
+# A single-user Nix install only gets sourced into login shells; this ssh
+# session is neither, so `nix` wouldn't otherwise be on PATH here even
+# right after a successful install.
+. scripts/lib/nix-bootstrap.sh
+ensure_nix_profile
+NIXOS_HOST_KEYS_DIR="$(pwd)/host-keys" nix build --impure \
  --no-use-registries --no-accept-flake-config "${NIX_OPTS[@]}" \
-        ".#nixosConfigurations.${flake_target}.config.system.build.tarball" \
-        --out-link "${repo_root}/result-${flake_target}"
-      local_image="$(find "${repo_root}/result-${flake_target}/tarball" -maxdepth 1 -type f | head -1)"
-      echo "Built: ${local_image}"
+  ".#nixosConfigurations.${target}.config.system.build.tarball" \
+  --out-link "result-${target}"
+built="$(find "result-${target}/tarball" -maxdepth 1 -type f | head -1)"
+if [[ -z "$built" ]]; then
+  echo "ERROR: no tarball found under result-${target}/tarball after build." >&2
+  exit 1
+fi
+mkdir -p "$dest_dir"
+cp "$built" "${dest_dir}/${dest_name}"
+echo "Built and staged: ${dest_dir}/${dest_name}"
+REMOTE_SCRIPT
+      local_image="$remote_path"
+      echo "Built on ${node}: ${remote_path}"
    fi
  else
+    # PROXMOX_SSH_USER defaults to root (env.sh), which needs no sudo and
+    # can't assume it's even installed on a minimal node -- only shell out
+    # through sudo when actually running as a non-root SSH user.
+    sudo_prefix="sudo"
+    sudo_display="sudo "
+    if [[ "$PROXMOX_SSH_USER" == "root" ]]; then
+      sudo_prefix=""
+      sudo_display=""
+    fi
    if [[ "$dry_run" -eq 1 ]]; then
-      echo "[dry-run] would build: nix build --no-use-registries --no-accept-flake-config${nix_opts_display} \\"
+      echo "[dry-run] would build on ${node}: nix build --no-use-registries --no-accept-flake-config${nix_opts_display} \\"
      echo "[dry-run]   .#nixosConfigurations.${flake_target}.config.system.build.diskoImagesScript"
-      echo "[dry-run] would run:   sudo ./result-${flake_target} \\"
+      echo "[dry-run] would run:   ${sudo_display}./result-${flake_target} \\"
      echo "[dry-run]                --pre-format-files host-keys/${flake_target}_ssh_host_ed25519_key /etc/ssh/ssh_host_ed25519_key \\"
      echo "[dry-run]                --pre-format-files host-keys/${flake_target}_ssh_host_ed25519_key.pub /etc/ssh/ssh_host_ed25519_key.pub \\"
      echo "[dry-run]                --build-memory 2048"
+      echo "[dry-run] would stage the result at ${remote_path}"
      local_image="<built-image>.raw"
    else
-      echo "==> Building Disko image script for ${flake_target}..."
-      nix build --no-use-registries --no-accept-flake-config "${NIX_OPTS[@]}" \
-        ".#nixosConfigurations.${flake_target}.config.system.build.diskoImagesScript" \
-        --out-link "${repo_root}/result-${flake_target}"
-      echo "==> Running it (builds the .raw image in a temporary QEMU VM, needs sudo)..."
-      ( cd "$repo_root" && sudo "./result-${flake_target}" \
-          --pre-format-files "host-keys/${flake_target}_ssh_host_ed25519_key" /etc/ssh/ssh_host_ed25519_key \
-          --pre-format-files "host-keys/${flake_target}_ssh_host_ed25519_key.pub" /etc/ssh/ssh_host_ed25519_key.pub \
-          --build-memory 2048 )
-      local_image="$(find "$repo_root" -maxdepth 1 -name "*.raw" -newer "${repo_root}/result-${flake_target}" | head -1)"
-      if [[ -z "$local_image" ]]; then
-        echo "ERROR: expected a .raw image after the build but didn't find one in ${repo_root}." >&2
+      echo "==> Building Disko image for ${flake_target} on ${node}..."
+      # See the LXC branch above for why this is one %q-quoted command
+      # string rather than separate ssh argv elements.
+      printf -v remote_cmd 'bash -s -- %q %q %q %q %q %q' \
+        "$remote_repo_dir" "$flake_target" "$remote_dir" "$remote_filename" "$NIX_EXTRA_OPTS" "$sudo_prefix"
+      ssh "$ssh_target" "$remote_cmd" <<'REMOTE_SCRIPT'
+set -euo pipefail
+repo_dir="$1"; target="$2"; dest_dir="$3"; dest_name="$4"; nix_extra_opts_str="$5"; sudo_prefix="$6"
+declare -a NIX_OPTS=()
+[[ -n "$nix_extra_opts_str" ]] && eval "NIX_OPTS=(${nix_extra_opts_str})"
+cd "$repo_dir"
+. scripts/lib/nix-bootstrap.sh
+ensure_nix_profile
+nix build --no-use-registries --no-accept-flake-config "${NIX_OPTS[@]}" \
+  ".#nixosConfigurations.${target}.config.system.build.diskoImagesScript" \
+  --out-link "result-${target}"
+$sudo_prefix "./result-${target}" \
+  --pre-format-files "host-keys/${target}_ssh_host_ed25519_key" /etc/ssh/ssh_host_ed25519_key \
+  --pre-format-files "host-keys/${target}_ssh_host_ed25519_key.pub" /etc/ssh/ssh_host_ed25519_key.pub \
+  --build-memory 2048
+built="$(find . -maxdepth 1 -name '*.raw' -newer "result-${target}" | head -1)"
+if [[ -z "$built" ]]; then
+  echo "ERROR: no .raw image found in ${repo_dir} after build." >&2
  exit 1
-      fi
-      echo "Built: ${local_image}"
+fi
+mkdir -p "$dest_dir"
+mv "$built" "${dest_dir}/${dest_name}"
+echo "Built and staged: ${dest_dir}/${dest_name}"
+REMOTE_SCRIPT
+      local_image="$remote_path"
+      echo "Built on ${node}: ${remote_path}"
    fi
  fi
 fi

-# --- upload (skip entirely if reusing an image already on the node) ------
+# --- upload -- only for an explicit --image; a build above stages its
+# result directly at ${remote_path} on the node already, and reusing an
+# image already on the node needs nothing transferred either. ------------
 echo
-if [[ "$image_already_remote" -eq 1 ]]; then
-  : # nothing to upload
-elif [[ "$dry_run" -eq 1 ]]; then
+if [[ -n "$image" ]]; then
+  if [[ "$dry_run" -eq 1 ]]; then
    echo "[dry-run] would upload: scp ${local_image} ${ssh_target}:${remote_path}"
-else
+  else
    echo "==> Uploading to ${node}:${remote_path}..."
    ssh "$ssh_target" "mkdir -p ${remote_dir}"
    scp "$local_image" "${ssh_target}:${remote_path}"
+  fi
 fi

 # --- create -----------------------------------------------------------------
@@ -516,7 +780,17 @@ if [[ "$type" == "lxc" ]]; then
  # systemd routinely uses (even plain getty units), and every getty
  # crash-loops on a denied mount every ~3s (visible as garbage on the
  # console) while core services like nsncd fail the same way.
-  create_cmd="pct create ${vmid} ${iso_storage}:vztmpl/${remote_filename} --unprivileged 1 --features ${PROXMOX_DEFAULT_LXC_FEATURES} --rootfs ${storage}:${local_disk_size} --hostname ${name} --cores ${cores} --memory ${memory} --swap ${local_swap} --net0 name=eth0,bridge=${bridge},ip=dhcp"
+  #
+  # ...,mount=nfs;nfs4: without it AppArmor blanket-denies the `nfs`/
+  # `rpc_pipefs` mount syscalls any NFS client share needs -- confirmed
+  # live on lxc-docker: `mount: /var/lib/nfs/rpc_pipefs: permission
+  # denied`. The value's `;` (Proxmox's own multi-fstype separator for
+  # this one feature, per PVE::LXC's use of PVE::ParseUtils::split_list)
+  # must stay single-quoted here: create_cmd is sent to `remote()`, which
+  # hands the whole string to `ssh` as a single command for the *remote*
+  # shell to parse -- unquoted, that `;` would be read as a remote
+  # command separator and silently truncate this into two commands.
+  create_cmd="pct create ${vmid} ${iso_storage}:vztmpl/${remote_filename} --unprivileged 1 --features '${PROXMOX_DEFAULT_LXC_FEATURES}' --rootfs ${storage}:${local_disk_size} --hostname ${name} --cores ${cores} --memory ${memory} --swap ${local_swap} --net0 name=eth0,bridge=${bridge},ip=dhcp"
  remote "$create_cmd"
  remote "pct start ${vmid}"
 else
@@ -0,0 +1,150 @@
+#!/usr/bin/env bash
+# Backs up the local sops age key (the private key that decrypts
+# secrets/*.yaml -- normally the one trusted as &admin) to an arbitrary
+# destination path, e.g. a USB drive or other offline storage, so it can
+# later be restored and handed to rotate-admin-key.sh if this machine's
+# copy is ever lost, or to run either script from a different machine.
+#
+# Usage:
+#   scripts/secrets/backup-admin-key.sh <dest-path> [--key-file <path>] [--force] [--dry-run]
+#
+# Source key resolution matches sops/age's own default order:
+#   $SOPS_AGE_KEY (inline identity text) if set, else
+#   --key-file if given, else
+#   $SOPS_AGE_KEY_FILE if set, else
+#   ${XDG_CONFIG_HOME:-$HOME/.config}/sops/age/keys.txt
+set -euo pipefail
+
+repo_root="$(cd "$(dirname "$0")/../.." && pwd)"
+sops_yaml="${repo_root}/.sops.yaml"
+
+# shellcheck source=../env.sh
+source "${repo_root}/scripts/env.sh"
+# shellcheck source=../lib/sops-age.sh
+source "${repo_root}/scripts/lib/sops-age.sh"
+
+# Pin cwd for the same reason rotate-admin-key.sh does: age/sops calls
+# below should never depend on wherever the caller's shell happened to be.
+cd "$repo_root"
+
+usage() {
+  cat <<EOF
+Usage: $0 <dest-path> [--key-file <path>] [--force] [--dry-run]
+
+  <dest-path>        Where to write the backup. Parent directories are
+                     created as needed. Written with 0600 permissions.
+  --key-file <path>  Read the key from here instead of the default
+                     sops/age resolution (\$SOPS_AGE_KEY_FILE, then
+                     \${XDG_CONFIG_HOME:-\$HOME/.config}/sops/age/keys.txt).
+                     Ignored if \$SOPS_AGE_KEY is set (that always wins,
+                     same precedence sops/age itself uses).
+  --force            Overwrite <dest-path> if it already exists.
+  --dry-run          Print what would happen; write nothing.
+EOF
+}
+
+dry_run=0
+force=0
+key_file="$DEFAULT_SOPS_AGE_KEY_FILE"
+args=()
+
+while [[ $# -gt 0 ]]; do
+  case "$1" in
+    --dry-run)
+      dry_run=1
+      shift
+      ;;
+    --force)
+      force=1
+      shift
+      ;;
+    --key-file)
+      key_file="${2:?--key-file requires a path}"
+      shift 2
+      ;;
+    -h | --help)
+      usage
+      exit 0
+      ;;
+    --*)
+      echo "Unknown option: $1" >&2
+      usage >&2
+      exit 1
+      ;;
+    *)
+      args+=("$1")
+      shift
+      ;;
+  esac
+done
+
+if [[ "${#args[@]}" -ne 1 ]]; then
+  usage >&2
+  exit 1
+fi
+dest="${args[0]}"
+
+nix_extra_opts
+
+if [[ -n "${SOPS_AGE_KEY:-}" ]]; then
+  echo "==> Source: \$SOPS_AGE_KEY (inline identity from the environment)."
+  src_content="$SOPS_AGE_KEY"
+else
+  [[ -s "$key_file" ]] || {
+    echo "ERROR: no key found. \$SOPS_AGE_KEY is unset and ${key_file} doesn't exist or is empty." >&2
+    exit 1
+  }
+  echo "==> Source: ${key_file}"
+  src_content="$(cat "$key_file")"
+fi
+
+# Round-trip through a private scratch file (rather than trusting the
+# source string as-is) so age-keygen -y validates it's a real identity
+# before anything is written to <dest-path>.
+scratch="$(mktemp)"
+trap 'rm -f "$scratch"' EXIT
+( umask 077; printf '%s\n' "$src_content" > "$scratch" )
+
+src_pub="$(age_pubkey_from_identity_file "$scratch")" || {
+  echo "ERROR: source doesn't look like a valid age identity (age-keygen -y failed)." >&2
+  exit 1
+}
+echo "    public key: ${src_pub}"
+
+current_admin_pub="$(sops_yaml_admin_pubkey "$sops_yaml")"
+if [[ -n "$current_admin_pub" && "$current_admin_pub" != "$src_pub" ]]; then
+  echo "NOTE: this key does not match .sops.yaml's current &admin entry (${current_admin_pub})."
+  echo "      Backing it up anyway -- this script doesn't require it to be the admin key."
+fi
+
+if [[ -e "$dest" && "$force" -ne 1 ]]; then
+  echo "ERROR: ${dest} already exists. Pass --force to overwrite." >&2
+  exit 1
+fi
+
+if [[ "$dry_run" -eq 1 ]]; then
+  echo
+  echo "[dry-run] would write $(wc -c <"$scratch" | tr -d ' ') bytes to ${dest} (mode 0600)"
+  [[ -e "$dest" ]] && echo "[dry-run] would overwrite existing file (--force given)"
+  echo "[dry-run] Nothing was written. Re-run without --dry-run to apply this."
+  exit 0
+fi
+
+mkdir -p "$(dirname "$dest")"
+install -m 600 "$scratch" "$dest"
+
+dest_pub="$(age_pubkey_from_identity_file "$dest")"
+if [[ "$dest_pub" != "$src_pub" ]]; then
+  echo "ERROR: ${dest} was written but its public key doesn't match the source -- investigate before relying on this backup." >&2
+  exit 1
+fi
+
+cat <<EOF
+
+Done. Backed up to: ${dest}
+  public key: ${dest_pub}
+
+This is a private key -- store it somewhere offline/secure, not in this
+repo or anywhere it'd get committed. Restore it with:
+  scripts/secrets/rotate-admin-key.sh ${dest}
+EOF
@@ -2,7 +2,7 @@
 # Generates a new machine's SSH host key by an arbitrary name, before it
 # necessarily has a flake target yet -- prints the .sops.yaml snippet to
 # add by hand. For any host that already has a flake target,
-# scripts/sync-host-keys.sh <target> does this same job plus the
+# scripts/secrets/sync-host-keys.sh <target> does this same job plus the
 # .sops.yaml/key_groups registration and re-encryption automatically; use
 # this script only to pre-generate a key ahead of adding the flake target
 # itself.
@@ -22,9 +22,13 @@
 # new machine.
 set -euo pipefail

-repo_root="$(cd "$(dirname "$0")/.." && pwd)"
+repo_root="$(cd "$(dirname "$0")/../.." && pwd)"
+# shellcheck source=../env.sh
+source "${repo_root}/scripts/env.sh"
+# shellcheck source=../lib/ssh-host-keys.sh
+source "${repo_root}/scripts/lib/ssh-host-keys.sh"

-hostname="${1:?usage: scripts/prepare-host-key.sh <hostname>}"
+hostname="${1:?usage: scripts/secrets/prepare-host-key.sh <hostname>}"
 sops_yaml="${repo_root}/.sops.yaml"

 if [[ ! -f "$sops_yaml" ]]; then
@@ -41,9 +45,10 @@ if [[ -f "$keyfile" ]]; then
  exit 1
 fi

-nix-shell -p openssh --run "ssh-keygen -t ed25519 -N '' -C '${hostname}' -f '${keyfile}'" >/dev/null
+nix_extra_opts
+generate_host_ed25519_key "$hostname" "$keyfile"

-age_pub="$(nix-shell -p ssh-to-age --run "ssh-to-age -i '${keyfile}.pub'")"
+age_pub="$(ssh_pubkey_to_age "${keyfile}.pub")"

 cat <<EOF

@@ -0,0 +1,193 @@
+#!/usr/bin/env bash
+# Rotates the &admin sops age key: decrypts with a backed-up copy of the
+# key CURRENTLY trusted as &admin, replaces .sops.yaml's &admin entry with
+# a new key already present in this environment, and re-encrypts every
+# secrets/*.yaml for the new recipient set. After this runs, the old key
+# can no longer decrypt anything -- this is a real, one-way handoff of
+# trust, not a preview.
+#
+# This is the automation for the manual steps create-proxmox-resource.sh /
+# sync-host-keys.sh print when they bootstrap a brand-new, not-yet-trusted
+# age key on a machine that's never had admin access before:
+#
+#   scripts/secrets/rotate-admin-key.sh /path/to/backed-up/admin/keys.txt
+#
+# The backup key's *public* key must match .sops.yaml's current &admin
+# entry -- this script verifies that by deriving it, it doesn't just trust
+# the filename or take it on faith. The new key defaults to wherever sops
+# itself would already look ($SOPS_AGE_KEY_FILE, then the XDG default), so
+# the common case is just pointing this at the restored backup.
+set -euo pipefail
+
+repo_root="$(cd "$(dirname "$0")/../.." && pwd)"
+sops_yaml="${repo_root}/.sops.yaml"
+
+# shellcheck source=../env.sh
+source "${repo_root}/scripts/env.sh"
+# shellcheck source=../lib/sops-age.sh
+source "${repo_root}/scripts/lib/sops-age.sh"
+
+# sops resolves .sops.yaml by walking up from the process's cwd, not from
+# the target file's own path -- if this script were invoked from somewhere
+# other than the repo root (or from inside another checkout/worktree that
+# happens to have its own .sops.yaml), `sops updatekeys` would silently
+# re-encrypt against the WRONG config's recipient list instead of this
+# repo's. Pin cwd here so every sops/age call below is unambiguous
+# regardless of where the caller's shell started out.
+cd "$repo_root"
+
+usage() {
+  cat <<EOF
+Usage: $0 <path-to-backed-up-admin-key> [--new-key-file <path>] [--dry-run]
+
+  <path-to-backed-up-admin-key>  age identity file for the key CURRENTLY
+                                 trusted as &admin. Only ever read -- never
+                                 copied or modified.
+  --new-key-file <path>          age identity file for the key to promote
+                                 to &admin. Defaults to \$SOPS_AGE_KEY_FILE,
+                                 then
+                                 \${XDG_CONFIG_HOME:-\$HOME/.config}/sops/age/keys.txt
+                                 (sops/age's own default resolution order).
+  --dry-run                      Print what would change; touches nothing
+                                  (.sops.yaml untouched, no sops updatekeys
+                                  calls).
+EOF
+}
+
+dry_run=0
+new_key_file="$DEFAULT_SOPS_AGE_KEY_FILE"
+args=()
+
+while [[ $# -gt 0 ]]; do
+  case "$1" in
+    --dry-run)
+      dry_run=1
+      shift
+      ;;
+    --new-key-file)
+      new_key_file="${2:?--new-key-file requires a path}"
+      shift 2
+      ;;
+    -h | --help)
+      usage
+      exit 0
+      ;;
+    --*)
+      echo "Unknown option: $1" >&2
+      usage >&2
+      exit 1
+      ;;
+    *)
+      args+=("$1")
+      shift
+      ;;
+  esac
+done
+
+if [[ "${#args[@]}" -ne 1 ]]; then
+  usage >&2
+  exit 1
+fi
+backup_key="${args[0]}"
+
+[[ -s "$backup_key" ]] || { echo "ERROR: backup key file not found or empty: ${backup_key}" >&2; exit 1; }
+[[ -s "$new_key_file" ]] || { echo "ERROR: new key file not found or empty: ${new_key_file}" >&2; exit 1; }
+
+nix_extra_opts
+
+echo "==> Deriving public keys..."
+old_pub="$(age_pubkey_from_identity_file "$backup_key")"
+new_pub="$(age_pubkey_from_identity_file "$new_key_file")"
+echo "    backup (old admin) key: ${old_pub}"
+echo "    new admin key:          ${new_pub}"
+
+if [[ "$old_pub" == "$new_pub" ]]; then
+  echo "ERROR: backup key and new key are identical -- nothing to rotate." >&2
+  exit 1
+fi
+
+current_admin_pub="$(sops_yaml_admin_pubkey "$sops_yaml")"
+if [[ -z "$current_admin_pub" ]]; then
+  echo "ERROR: couldn't find a '&admin age1...' line in ${sops_yaml}." >&2
+  exit 1
+fi
+
+if [[ "$current_admin_pub" != "$old_pub" ]]; then
+  echo "ERROR: ${backup_key} doesn't match the current &admin key in .sops.yaml." >&2
+  echo "  .sops.yaml &admin: ${current_admin_pub}" >&2
+  echo "  backup key pubkey: ${old_pub}" >&2
+  echo "Wrong backup file, or .sops.yaml has already moved on -- not touching anything." >&2
+  exit 1
+fi
+
+mapfile -t secrets_files < <(find "${repo_root}/secrets" -maxdepth 1 -name '*.yaml' | sort)
+if [[ "${#secrets_files[@]}" -eq 0 ]]; then
+  echo "ERROR: no secrets/*.yaml files found under ${repo_root}/secrets." >&2
+  exit 1
+fi
+
+# sops_can_decrypt <key-file> <secrets-file>: used both to confirm the
+# backup key still works before touching anything, and again after
+# rotation to confirm the new key does too.
+sops_can_decrypt() {
+  local key_file="$1" secrets_file="$2"
+  SOPS_AGE_KEY_FILE="$key_file" nix-shell "${NIX_OPTS[@]}" -p sops --run \
+    "sops -d '${secrets_file}'" >/dev/null
+}
+
+echo "==> Confirming the backup key can actually decrypt..."
+if ! sops_can_decrypt "$backup_key" "${secrets_files[0]}"; then
+  echo "ERROR: backup key failed to decrypt $(basename "${secrets_files[0]}") -- aborting." >&2
+  exit 1
+fi
+echo "    OK: decrypted $(basename "${secrets_files[0]}")"
+
+if [[ "$dry_run" -eq 1 ]]; then
+  echo
+  echo "[dry-run] would replace .sops.yaml's &admin line:"
+  echo "[dry-run]   - ${current_admin_pub}"
+  echo "[dry-run]   + ${new_pub}"
+  echo "[dry-run] would then re-encrypt (sops updatekeys --yes) for the new recipient set:"
+  for f in "${secrets_files[@]}"; do
+    echo "[dry-run]   secrets/$(basename "$f")"
+  done
+  echo
+  echo "[dry-run] Nothing was changed. Re-run without --dry-run to apply this."
+  exit 0
+fi
+
+echo "==> Rotating .sops.yaml's &admin key..."
+sed -i "s|^  - &admin age1[a-z0-9]*|  - \&admin ${new_pub}|" "$sops_yaml"
+grep -qF "$new_pub" "$sops_yaml" || {
+  echo "ERROR: sed edit didn't take -- .sops.yaml left unchanged, check it by hand." >&2
+  exit 1
+}
+echo "    Updated."
+
+echo "==> Re-encrypting secrets/*.yaml for the new recipient set..."
+for f in "${secrets_files[@]}"; do
+  echo "==> $(basename "$f")"
+  sops_updatekeys "$f" "$backup_key"
+done
+
+echo "==> Verifying the new key can decrypt everything..."
+for f in "${secrets_files[@]}"; do
+  if ! sops_can_decrypt "$new_key_file" "$f"; then
+    echo "ERROR: new key failed to decrypt $(basename "$f") after rotation -- investigate before committing." >&2
+    exit 1
+  fi
+  echo "    OK: $(basename "$f")"
+done
+
+cat <<EOF
+
+Done. .sops.yaml's &admin key is now:
+  ${new_pub}
+
+The old key (${old_pub}) can no longer decrypt any secrets/*.yaml
+re-encrypted above.
+
+Review the diff, then commit:
+  git add .sops.yaml secrets/*.yaml
+  git commit -m "Rotate sops admin age key"
+EOF
@@ -24,13 +24,21 @@
 # ever touches keys it itself manages.
 set -euo pipefail

-repo_root="$(cd "$(dirname "$0")/.." && pwd)"
+repo_root="$(cd "$(dirname "$0")/../.." && pwd)"
 sops_yaml="${repo_root}/.sops.yaml"
 keydir="${repo_root}/host-keys"
 editor="${repo_root}/scripts/lib/sync-host-keys-edit-sops.py"

-# shellcheck source=env.sh
+# shellcheck source=../env.sh
 source "${repo_root}/scripts/env.sh"
+# shellcheck source=../lib/nix-eval.sh
+source "${repo_root}/scripts/lib/nix-eval.sh"
+# shellcheck source=../lib/ssh-host-keys.sh
+source "${repo_root}/scripts/lib/ssh-host-keys.sh"
+# shellcheck source=../lib/sops-age.sh
+source "${repo_root}/scripts/lib/sops-age.sh"
+# shellcheck source=../lib/confirm.sh
+source "${repo_root}/scripts/lib/confirm.sh"

 mkdir -p "$keydir"

@@ -74,7 +82,7 @@ ensure_admin_decrypt_key() {
    return
  fi

-  local key_file="${SOPS_AGE_KEY_FILE:-${XDG_CONFIG_HOME:-$HOME/.config}/sops/age/keys.txt}"
+  local key_file="$DEFAULT_SOPS_AGE_KEY_FILE"

  if [[ -s "$key_file" ]]; then
    echo "Found existing sops age key at ${key_file}."
@@ -93,7 +101,7 @@ ensure_admin_decrypt_key() {
  mkdir -p "$(dirname "$key_file")"
  nix-shell "${NIX_OPTS[@]}" -p age --run "age-keygen -o '${key_file}'" 2>&1 | grep -v "^Public key:" || true
  local new_pub
-  new_pub="$(nix-shell "${NIX_OPTS[@]}" -p age --run "age-keygen -y '${key_file}'")"
+  new_pub="$(age_pubkey_from_identity_file "$key_file")"

  cat <<EOF

@@ -118,12 +126,10 @@ EOF
 }

 discover_targets() {
-  nix eval --json --no-use-registries --no-accept-flake-config \
-    "${repo_root}#nixosConfigurations" --apply builtins.attrNames \
-  | jq -r '.[] | select(. != "installer")'
  # installer is the one nixosConfigurations target that doesn't import
  # sops-nix at all (see CLAUDE.md's "Security Notes" -- hardcoded login
  # password instead) -- config.sops.secrets doesn't exist for it.
+  list_flake_targets "$repo_root" | grep -v '^installer$'
 }

 locally_managed_hosts() {
@@ -159,7 +165,7 @@ queue_host_sync() {
      echo "[dry-run] ${host}: would generate host key"
    else
      echo "==> ${host}: generating host key"
-      nix-shell "${NIX_OPTS[@]}" -p openssh --run "ssh-keygen -t ed25519 -N '' -C '${host}' -f '${keyfile}'" >/dev/null
+      generate_host_ed25519_key "$host" "$keyfile"
    fi
  else
    echo "==> ${host}: host key already present"
@@ -170,7 +176,7 @@ queue_host_sync() {
    if [[ "$dry_run" -eq 1 ]]; then
      age_pub="dry-run-placeholder-not-a-real-key"
    else
-      age_pub="$(nix-shell "${NIX_OPTS[@]}" -p ssh-to-age --run "ssh-to-age -i '${keyfile}.pub'")"
+      age_pub="$(ssh_pubkey_to_age "${keyfile}.pub")"
    fi
    add_keys_json="$(jq --arg host "$host" --arg key "$age_pub" \
      '. + [{host: $host, age_key: $key}]' <<<"$add_keys_json")"
@@ -237,7 +243,7 @@ apply_edit_plan() {
      while IFS= read -r basename; do
        [[ -z "$basename" ]] && continue
        echo "==> secrets/${basename}"
-        nix-shell "${NIX_OPTS[@]}" -p sops --run "sops updatekeys --yes '${repo_root}/secrets/${basename}'"
+        sops_updatekeys "${repo_root}/secrets/${basename}"
      done <<<"$changed"
    fi
  fi
@@ -357,8 +363,7 @@ cmd_regenerate_all() {
  echo "image/tarball before it can decrypt secrets again."

  if [[ "$dry_run" -ne 1 ]]; then
-    read -rp "Type REGENERATE to confirm: " confirm
-    if [[ "$confirm" != "REGENERATE" ]]; then
+    if ! confirm_typed "REGENERATE" "Type REGENERATE to confirm: "; then
      echo "Cancelled."
      return
    fi
@@ -0,0 +1,110 @@
+#!/usr/bin/env bash
+# Detects and fixes drift between the ed25519 SSH host key nix-cache is
+# actually serving right now and vars.nixCacheHostKey (variables.nix) --
+# the value modules/nix-cache/remote-builder-client.nix bakes into every
+# client's declarative programs.ssh.knownHosts, and
+# scripts/proxmox/configure-nix-cache-client.sh hardcodes as its own
+# default for non-NixOS clients.
+#
+# This value has no automatic source of truth: nix-cache's host key is
+# generated once (first boot / container recreate) and never touches this
+# repo again unless someone remembers to update it by hand afterwards. It
+# drifted silently once already -- confirmed live: variables.nix recorded
+# a key that no longer matched what nix-cache actually presented, which
+# would fail every real client's SSH host-key verification for
+# distributed builds without ever producing an obvious error pointing
+# back here (a client just sees "Host key verification failed" against
+# *some* key, with no hint that the trusted value itself was stale).
+#
+# codex-maintenance.sh runs this in --check mode on every invocation so
+# that drift surfaces as a warning instead of a future debugging session.
+#
+# Usage:
+#   scripts/secrets/sync-nix-cache-host-key.sh [--check] [--dry-run] [--host <name>]
+#
+#   --check     Only report drift (exit 1 if found, 2 if nix-cache is
+#               unreachable); never writes. For CI/maintenance use.
+#   --dry-run   Show what would change; never writes.
+#   --host      Override the hostname to scan (default: variables.nix's
+#               nixCacheHost / env.sh's NIX_CACHE_HOST).
+set -euo pipefail
+
+repo_root="$(cd "$(dirname "$0")/../.." && pwd)"
+variables_nix="${repo_root}/variables.nix"
+client_script="${repo_root}/scripts/proxmox/configure-nix-cache-client.sh"
+
+# shellcheck source=../env.sh
+source "${repo_root}/scripts/env.sh"
+
+check_only=0
+dry_run=0
+host="${NIX_CACHE_HOST}"
+
+while [[ $# -gt 0 ]]; do
+  case "$1" in
+    --check) check_only=1; shift ;;
+    --dry-run) dry_run=1; shift ;;
+    --host)
+      host="${2:?--host requires a hostname}"
+      shift 2
+      ;;
+    -h|--help)
+      sed -n '2,23p' "$0"
+      exit 0
+      ;;
+    *)
+      echo "ERROR: unknown argument: $1" >&2
+      exit 1
+      ;;
+  esac
+done
+
+current_value="$(grep -oE 'nixCacheHostKey = "[^"]+"' "$variables_nix" | sed -E 's/nixCacheHostKey = "(.*)"/\1/')"
+if [[ -z "$current_value" ]]; then
+  echo "ERROR: couldn't find nixCacheHostKey in $variables_nix" >&2
+  exit 1
+fi
+current_type_blob="$(awk '{print $1, $2}' <<<"$current_value")"
+current_label="$(awk '{print $3}' <<<"$current_value")"
+
+echo "Scanning ${host} for its current ed25519 SSH host key..."
+nix_extra_opts
+scanned="$(nix-shell "${NIX_OPTS[@]}" -p openssh --run "ssh-keyscan -t ed25519 -T 5 '${host}'" 2>/dev/null | grep -v '^#' | head -1 || true)"
+if [[ -z "$scanned" ]]; then
+  echo "ERROR: couldn't reach ${host} (or got no ed25519 host key back) via ssh-keyscan." >&2
+  exit 2
+fi
+scanned_type_blob="$(awk '{print $2, $3}' <<<"$scanned")"
+
+if [[ "$current_type_blob" == "$scanned_type_blob" ]]; then
+  echo "Up to date: ${host}'s host key matches variables.nix's nixCacheHostKey."
+  exit 0
+fi
+
+echo "DRIFT DETECTED:"
+echo "  variables.nix has: $current_type_blob"
+echo "  ${host} is now:    $scanned_type_blob"
+
+if [[ "$check_only" -eq 1 ]]; then
+  echo
+  echo "Run 'scripts/secrets/sync-nix-cache-host-key.sh' (no flags) to fix." >&2
+  exit 1
+fi
+
+new_value="${scanned_type_blob} ${current_label}"
+
+if [[ "$dry_run" -eq 1 ]]; then
+  echo "(--dry-run: would update variables.nix and ${client_script##*/} to:)"
+  echo "  $new_value"
+  exit 0
+fi
+
+sed -i "s|nixCacheHostKey = \"[^\"]*\"|nixCacheHostKey = \"${new_value}\"|" "$variables_nix"
+sed -i "s|NIX_CACHE_HOST_KEY:=[^}]*}|NIX_CACHE_HOST_KEY:=${new_value}}|" "$client_script"
+
+echo "Updated variables.nix and ${client_script##*/} to:"
+echo "  $new_value"
+echo
+echo "This only takes effect on already-deployed NixOS clients after their"
+echo "next rebuild (programs.ssh.knownHosts is declarative). Review with"
+echo "'git diff', then run 'bash scripts/codex-maintenance.sh' before committing."
@@ -5,76 +5,85 @@ sops:
    age:
        - enc: |
            -----BEGIN AGE ENCRYPTED FILE-----
-            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSBpWjNSdEdZbUUzamswa08w
-            aCtzSHB0bFVZMnYxTkpuM1psdVYzWW55SzMwCkliMWVOUlBqRG5wOGZjQVg4MkFz
-            NEVkMXdkTjhWRlZmVGlzZElid2pUMXMKLS0tIGtHUmRCNXNhVmloUHYzQnE5YlBS
-            YnVSQjJlT3JnQ1RNMm9xV2xKOGRZUDAKc4VTl9NEI9Rv8+4J3JTeHTt2h8Dr2IJv
-            tfvoNJQM/w6RAJWNTkaDmzZa9OnUW+grDlBQKlDuAnr6fZmuNTH2hQ==
+            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSBaMUpxYmUzaVY4d1pRY3g3
+            empaVUJSN0JaSlNQQlJtZENwc0VMYVhJSkFvCmJQMkpSd3RoYzlKQjBSZWErQzR2
+            aG5SVndOQWpSRTBDSWJVQkg0c0hiNFUKLS0tIHhiaEdpY3gwZkpCcHl2TW5CNThn
+            aVVUQy9Qd0trb0RNdUpVTXdrdGlrTmcK1uphQAyDV+Gk5+K1YOqw1Z8ynGP5sAPF
+            q5icujja/SGexX18hPYXbkyUtOrBYjW62gCuGJinSBPROoFUJbiP7g==
            -----END AGE ENCRYPTED FILE-----
-          recipient: age10nd382a9klsn2mrs60emdtsxe43pht3a0m9p29phfrhy0wfyt3vsq9r667
+          recipient: age1njap586hc0q43kr03g6c8eqhdsmk8zcafkl3f83xwlc2gqhlmfgs4tmwad
        - enc: |
            -----BEGIN AGE ENCRYPTED FILE-----
-            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSBOR25UN1c0aE5SYWphbU0y
-            SHRTZ1B0WC9NU3Z5VHpzTXpLSUxHTDI1ZFE0CnFpYUN1eGZQejJMblZPd1ROeUth
-            dklZYVVNa1ZNZ1d4dW9vMCsvQWp1RkEKLS0tIERxakx5L0JrQitib1EyNDRMbDQ5
-            Z3hDWUFEazdxczVhaHJYK3VZeEJSSDgKkw9T4ZuT+VHIF4WopqRHt8vW30kOysJ3
-            vOq6EZ3Fqkgmoxm69Zp2gFnuE9GZIBy3VPQVLU2k6dZGJ3IvmLYeBA==
+            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSBKOWZxcFlhRHhKelhDS29M
+            NGRlTEhJUGUzcFV6QVFCdTNkdEN3MlljWnl3CnI3LzVxSHBwSi9TYlRUcFdyN2py
+            cVZBV0Q3Z3FhRXA0T1NFQzd2R00yeEUKLS0tIHkxL2dHV3RkVFYxZTJNTVZvVFIr
+            TXpJZzdnYlpJaXBmcjdWWUtxNkc4dWMKVsImJiavzUzSFn78pciNJPHaS3KWqJer
+            VkxF6kF3tl2HmW46eVXtsQowdu+zVR9HS35i/HvQ1r1TyP6qT5ofcQ==
            -----END AGE ENCRYPTED FILE-----
          recipient: age19gfn2yedg76dmztm4hncr7vf3r3c9j0qpt4rap7y7gersjk4m3ks2lhd0e
        - enc: |
            -----BEGIN AGE ENCRYPTED FILE-----
-            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSA0THJzMFBTTCtDMWRmZ25M
-            dU55OVhBb0trWWRUNlArTnEzRjhiYngvRENNCjF4d0M5NlYyQW50TTdMRXpuUjRr
-            M1NwV05JOHV6T2cxT2FheVpuZ0w2T0kKLS0tIFBxdlVpVEoxOUpSWjk1ejRsK1NM
-            V1UwTU1scG91L2FIemtwSW5JbFlmeG8K/1WIlaIidy3x3ptoRpS/DG88064LQ6Mq
-            GbfB0jfq5PILDQMMuZu5oIBY31SxwnhZ02Ns7gA67kgNIRSCmk9WyQ==
+            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSAyWjdSanRRaEI4VHFZVkdw
+            NkxMODRuakFJTFNoTHZIRHptZFNxaGZ3K3lnCjJGR1FJalRsYmtLcHFxZW8yNU5W
+            MzBjWmltbzI3MTByUjB6djlEdllHNXMKLS0tIEhEOVhLVjZkRi9vUEtDWUhxT0NX
+            eUZ3bGdEaHdGbXZIYkowYUZuTWJ3d2MKMwgxOqlMH7GfLlseD4J277Dcg0KCD3d5
+            jwJDb82kRWoBMicTJZXoq/5oe5blJNa7dWYoqgkYxMA2O+0igT+I6g==
            -----END AGE ENCRYPTED FILE-----
          recipient: age1ll6hj5ggruetgjwjfnplpn5xtq35uhlcdflksx3xmnjm6s3uad9sz70jkf
        - enc: |
            -----BEGIN AGE ENCRYPTED FILE-----
-            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSBmRURQVGw1a1E1MkIzV2pa
-            RG5HSkM0c0huUGVWcnFZOGlacGlGOHFMTVFrCm5OS09HRFc3TGVUYmtzTStxL0Q5
-            N2hRMEcxUE9MTmZXL0wvME5EZXF1Z00KLS0tIHdHMVVHcTZzMmdXU0s4QlVqSS9Y
-            ZUVmcWhPaURIUFJGR0V4bUZwKzM1bm8KlvGMNEClbLlfvJqNQHhd0dI4ihShLChF
-            GI/fydgrBruw3Otv6KLZu3CBC7iNcKlvZxz+YGD2qbicmyQ5hAhDSQ==
+            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSBsZzdRMm9zdlJHckFoREVs
+            UkVXL3dCeWRuN2NqcnVsOWVNT1FLUHY3andrCmNFY0ZCby9SdnUyYlV6R05YNDB0
+            em43SjRCNVhYbmpRZUVWT0cxQlhGdmsKLS0tIDZHazNyck5VNHBuNVM5bmRZUlpR
+            QzBSNy84VDdLVkZZbnNlUFYydXlreEEKYZaR2b7tyRAhPdP+ytpP0veUTi7pY9Nw
+            pK0h4hcegLNYJL1AfOYwFQoW7vb256GdmwdcuuBl1YBGXWGraaBnZg==
            -----END AGE ENCRYPTED FILE-----
          recipient: age120le4a5l8dh3lyfgvmj3d9ksmej6ajs5mer5y7r0vfg3x9fn69dqf8xgzu
        - enc: |
            -----BEGIN AGE ENCRYPTED FILE-----
-            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSA5bWpFenBlQldna3RhSFpr
-            bEJBaHJDMzM3OHlqTmozcWU0VDM1bTFUWFZzCnZtNHZjZ1U1RzNkUlBHZFozWXdt
-            VVkxQjMvTDJtbFZnclpkUEd4TEVmNTAKLS0tIFlhV2ZSSzJLRVNoMmFyVktDOElR
-            YUxqZUFoY1ZWeGlldGplMjVQa1A5aUUKWelY6yO7Mr6dRvj4MVMbq/Z9JgrAnahz
-            BDhHqObzJrOCtfDCTWiYuP+0yvIFWItMWhGSMw9MwwivvwnrEa+ZuQ==
+            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSBFSnZiOGpsL1BESWVEdUxx
+            dXc5LzBHTlNodGJ1S3hOeHd5Wmgxb3BPSHl3CnBEWDNTc3NDdzN3RHQxUlNLOEs5
+            RU1SS2tVT29XbDJCWVliWnVkekN4L1kKLS0tIGFqY2pNK2h2S2ZWMndrRVN6eUdN
+            M0NLY2EvTTVIYlZvdk9XY0NwNE14ZlEKcOwgCK3g56kId/4tEt+2iCcylisn+Fca
+            5VWamsXdbwxbxmCEEUbgN3aHrdVz3mV4+8FZqA34yXz8pc45/PUcFg==
            -----END AGE ENCRYPTED FILE-----
          recipient: age1qz9d4ka4xgexujyd247s7lp737sulp5fhxl5d65fj2ykvc4j4edqrsdks8
        - enc: |
            -----BEGIN AGE ENCRYPTED FILE-----
-            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSBiK2hKb2VaVnoyaEVYUHZZ
-            OWVUSGtONGs5dEljTjJQdlhEcjNjdjViT2pVCkpaOHVZMlpXOFRveVlMeXZqWmoz
-            ZHJRQTR2dmJQSEozeTRGMEdUdFlmZ2MKLS0tIERWS1RVdW1jQytBZzlkb3puNjhH
-            ZjdlZmtzNXVOQ25DeCthUzhRRm1MT2cKaxc7zGm57iJFSeYc2IPqF4Eaxa44nR37
-            pWZw+erG4F9AAZ2F047q+oLKe0B8FLSF54IbcXdQhitgGNR7B2HVeA==
+            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSBJU1cydFFuRnpCUU5mbjFu
+            TTIxREkxZ1hMalVtNjNjcHVaUXpPNWdib2tzCkRScWRTWHhxN3lhckI4UFpMSFRa
+            RGxWcldlWnd5SVJFNWxQWjB3R0pMb3MKLS0tIGdjLzlhTHgyT2hjTmRTK1RiZmxS
+            OWRWYklBWkoyUG8raFNzd3JlRUtEUEUKw+NdAp1Mz0dEOUGPbqCV8y7029I3Kye0
+            keU2T29JGCN1D6x//1NcMUYSaFZKgv0ZVSjVUCl1EnmlJ0nBdbaDXA==
            -----END AGE ENCRYPTED FILE-----
          recipient: age120whqj96g26lsgy4udvgsn8dc9lumh8jeu3a564fx79rjr5lxffqmrljuu
        - enc: |
            -----BEGIN AGE ENCRYPTED FILE-----
-            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSA1ekhUTG5VOFErL3pFeWZM
-            RG9NVnN6NFl3bzlFeTQzdHFtZmhwem04alQ0ClpJRStObERMZ0w2V0NhR1FSeW96
-            M1d2V2NjUkUrLzN2ZVNSbGY4bll5WmsKLS0tIC94dVFQcXJ6d3pLU0VHNEFGR0ls
-            a1Q2UmNuSjVMNG5XZGZKV1VmNHFPQXcKQJrZGw/9fPnXeFZ4omrkEgrzwplhwvRW
-            i0FXuepoU353sR7enyL34qPoOdm05ivowuPKNzkq8D4i5AF6vGv+YA==
+            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSBnNFlzYVBqaGFDVE9xbmt5
+            OVd4ZlZRdEVJd0JFdkRIYVA5ZUEwYjJjWVJjCnZzTExNbDlYbGN6c1dYU2ZlNEVs
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+            bmxIYWk1VThsaFhxRDlOOGhGQ2tYamsKs+PcOiaeNFujCWwZBr+nq1MzrGohl+ch
+            TASI7eNsiHmSVRzSMHv4mX+8yXDHIRgHbFuUty2gdgGFLRjYXe4gDA==
            -----END AGE ENCRYPTED FILE-----
-          recipient: age164px2a8e48ptsf9ngtan38aa6jls4jdl26mzrgzf6sn3vcvt49hqjrgr8w
+          recipient: age1xjst4frdh0th6q8m7p7u9g5af7ty5jqeum0p6z8a52a9q7st7ewqw8yl9j
        - enc: |
            -----BEGIN AGE ENCRYPTED FILE-----
-            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSBoZ2lHM2RBQ3lUK216dkcr
-            Y3RrcXR3QTdFVjJRWlhpQWVFQ1cyZWNabkRFClAwRi9PSHF5ZWFSUzJuRXF3bU1R
-            b0U5TFRZaFdmR1NMS3RRT3E3M2hUdE0KLS0tIEtrUy8ydkNyVHBiOVR6WEdjV2VN
-            NVJHUVgwRkhxcmlwcFkrRlFwTEF6YVkKzXyJk0UnmUsvb+NzNVcf/gf7OEEt3P/K
-            OIGxDrGfs/zNQgeKXNbQlQ4p4jOaybG8aCmX+A4qTk6/I8yY8LTJWg==
+            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSBkcmVQYXV1NzRrQ2IxTElt
+            QUJRMkhiUUJqRDdwQW03K0lCTEtkSTU5UDJrCjh6SldpQkF1NzIybTJTdnBlOHdQ
+            VlREMy9hM0ZaL21Pa0VPUzcvb0pQQjQKLS0tIFcrK0I3Z3Nhem45eHpZYmdWeit6
+            eXFtRHVxODhaNTVDdVR1a2tOb1N1U1EKZBdLHq8PRMKX2ndFr3AxFVAZRyvhFa1u
+            72R5tordo4IR3HSxG3Z06rokOITd+KKhaQ8NEWEC8qioAAMxEC9QWw==
            -----END AGE ENCRYPTED FILE-----
          recipient: age10at8862478urh0eeuwh8hzln6ck78jgwtztgxatwqlzwagg77y5snm4xzg
+        - enc: |
+            -----BEGIN AGE ENCRYPTED FILE-----
+            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSA0WjJPbXhXNTNyQUZzMmxS
+            Rkd3Yk5Ga3pPRXFtMFpXcmpBZ3RJYnJlaHhjClRDbFBHRVZ0SDdrNFdVWmUwalpT
+            WUt5a2RUTnQ4VFBGMlowR3JycDM3aXMKLS0tIERSeFd4cGdSbzRpSmpSQnB1Yng5
+            OHBma3lYeWEwQ2RvelpzZHRkN1JPWFEKLXkJfEkH3lo5Z4mj8PZXTfAfZn6B46To
+            U0G54tUh0U1EeMnI5ZPRGwDxi5K0eD68HjeE9MBvFBysOChP/ANDPQ==
+            -----END AGE ENCRYPTED FILE-----
+          recipient: age1ezk9x53zt8kcnscdm80jcyf0xq97vndv7jsn3rl8cc0cwm2jmpmq372dzs
    lastmodified: "2026-07-19T02:30:40Z"
    mac: ENC[AES256_GCM,data:UiL3VMDF6rq4Nr87KspcDx434q3tfNXeb5pwH2O+4ssNQ6xzcYDdzXBnhAY3zLBsqPMKrvHBd4Ot/gEMcq3FMIVe7Q6p9yWKpep66KZ/yWEhAlwIVhD79Oj8VS+1CHKjf25zpRdhZorp04oeFQQd9VfjJB4EE/Q1aVbwTGlpIic=,iv:i/0conaFgFia+wzNTdUL6tlSTw35HTK3Ap1Sr5RGHf8=,tag:ULbz5FllShA/JjlSRdxA0g==,type:str]
    unencrypted_suffix: _unencrypted
@@ -4,31 +4,31 @@ sops:
    age:
        - enc: |
            -----BEGIN AGE ENCRYPTED FILE-----
-            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSBDbHd1Y1dpa2ZiQ2E1bXRP
-            SnkrWHI0V2U1eGFKY0RZamZQQjluS0hGeENZCmduUFQyd1Q5RkZGMGFoenJhNmZh
-            VmZ2OStNaFpJejFxQ2JUZXFpNThaMncKLS0tIEhJdGdQeXEzb25Nbk5YZktCWVUz
-            NUJDUWRoTkd5R2pFblZjS0NSbVR5dkkKDYeW+zRpha04/CasFM91K6v1PpkNGHRu
-            qAoKs9KSg9VxS7ya8RuLmylKRdpPkupm/8SXIJvQuCXp5LWmNJ4zkA==
+            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSBPWE1HTUhiSUp5ZEUwWEpI
+            bGpkZlBIMUo5ZlYrQ09SN3Q1a0ZkQ0ZnOEhVCnJPNEZQenVWWGZiODlzQzNEc1Zq
+            c3l4OWZJTElJc2Y2UE15OGtEUzhyY1EKLS0tIHNJUStyWnlQWjZBbEZjQ3UwdUpz
+            ZndoUDR6bisrNGJCUHk3TGI4bTZaMFUK87fFsm9ne9s+PK2pcwtrDjqyGBss2r2E
+            8lhqoeiKZ2j96z8kP/7ChzovwTCmqdcmAQuyNQD+ZAFijseipSvfbQ==
            -----END AGE ENCRYPTED FILE-----
-          recipient: age10nd382a9klsn2mrs60emdtsxe43pht3a0m9p29phfrhy0wfyt3vsq9r667
+          recipient: age1njap586hc0q43kr03g6c8eqhdsmk8zcafkl3f83xwlc2gqhlmfgs4tmwad
        - enc: |
            -----BEGIN AGE ENCRYPTED FILE-----
-            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSB4UktiUUdmd092bnZMdFMz
-            Q05xVlhnNzhPZUY4TjF5bjRCbklacTdJd1RBCnJ4bEVMaWRLZExIUFVEUDBXTnlV
-            MDU4WUk5VlJjdlhVUVpzZXlnWHhqTjQKLS0tIE9iclhGVElPcU9OLzF0bEVjMjVp
-            YzlQTGFYZEhLdTk3N3ZramVjVGRXREUKjOjqO/jX5iEKN43WiJ8qS/1mDfxdj8uO
-            K7Yyc/Yj0qMvGwLNzphjmbT29P7dXk4Ht4TedqCd+8DfhpOgLVIaSA==
+            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSBUYi9SRFFGV3Z6cFd2Znk5
+            b2FLbWtzTllJMDBUaGk0NTViOTNBa2hQclVZClZHKzNhbGVjQUJhWkFWdTFBMG5a
+            cUFJdUdyVG5HQXJRRnJId3hqRTN2cXMKLS0tIEFMRjh3WE1ON0U2TTNTZ3hxMTR4
+            ZGRlemlIbDZKeExmVHROc3Eyak5DdzQKaLwIVDi6BN4cxpVxJoqTYvJETPOp4thc
+            l9uVMvIGuEsEZgDsvShw1dYLljd+uGy/A+dXbcxIUCP/mmPkwmd1Pw==
            -----END AGE ENCRYPTED FILE-----
          recipient: age120le4a5l8dh3lyfgvmj3d9ksmej6ajs5mer5y7r0vfg3x9fn69dqf8xgzu
        - enc: |
            -----BEGIN AGE ENCRYPTED FILE-----
-            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSBjaXpvQU9yRUc3ektPMmU5
-            Q0xLWU9mYXVOeTVBNGNsZzJPa1lkVlRUZHlvClhoSVV6YjB1Q3pTTzVvNFlNYkU4
-            Y2RrbFk5SUFKSDVjeFU0Wlc2aGFUMFUKLS0tIDlVeXM4WWRUakg4Zk5mcjdJL3VC
-            S1k5eFBpVnREQlZwYllpeTNhWW5GS1EKi2sMwyJJ0D8acjCZmxlcwdU1sglBuxR7
-            2SEMsctdGC+5E3ilPXvPpZ5RONZHbXxn6kQRBlBv6AJERpGDzsfgfA==
+            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSArOWovSW9DeFpxL0VDUDQ3
+            SHUwTzJVZUtPV01ZRkdCUXZGL2lTRCtCNFNnCjBSNExqRW5mTEN5SFVucHJHSzZt
+            cDlNc3BjY3M1c1k1Z2tkVEg4R1pacGsKLS0tIEFWbHNKZW0vbVh1Y2VhQW93OUwx
+            MWV0eW9sOXdQd0l2ZjlWOEVVc1dwcTgK2s4p9xoNkawH2OkGsl80bNIo3ad5vn4W
+            Z2w+jwppSoUmbQnD3WFbLmSSxmuobmU8HILwElv6SZu+KE3aspF6XA==
            -----END AGE ENCRYPTED FILE-----
-          recipient: age164px2a8e48ptsf9ngtan38aa6jls4jdl26mzrgzf6sn3vcvt49hqjrgr8w
+          recipient: age1xjst4frdh0th6q8m7p7u9g5af7ty5jqeum0p6z8a52a9q7st7ewqw8yl9j
    lastmodified: "2026-07-19T23:30:21Z"
    mac: ENC[AES256_GCM,data:kLGE2xawQT7mx+sfw68hmGk5nCEGiEjZrqTEl9B1dtQmTrMwmoVr/1RISi4LfJrwxy31mDgff4lcIL4wIJuM373uk3X8j4RNyYQNTfKEkORT6r8NHeepNs267O77pKGd7OmcM4MT/BqOnB8ELS7Wlf2ect7CAlvUUVyc8icxgZE=,iv:EYLDsHYHZ1XOQXafOTqHHWpk/OBNq/R6IJnOBYV33E4=,tag:thxrCPC5oGvDjhK7Dz87YA==,type:str]
    unencrypted_suffix: _unencrypted
@@ -3,20 +3,20 @@ sops:
    age:
        - enc: |
            -----BEGIN AGE ENCRYPTED FILE-----
-            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSBxaFZURjAxMGRJZEJ5MW1x
-            ZjVwWEQrQlkwNmRibVNiL2RpTTFLeUVDQ3hRCkVIamVnZkM1MnlueloxMHVFQnBF
-            RjV2bnUrZUo4WGZJTmR4Y0xITkxRUkUKLS0tIGlJdVQ5MFBubVhxRUVMWW0wSGpP
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-            VaTdr5qkf8LNNvPI0fxsXA9is5cqeg+KbDRHtUumEhNp6Zrf8zWBkw==
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+            +K0QiZLTKmmDcr4bRhZ32VE7R7GRwtMNnOP/mElZvPAyWyHHhRiOHg==
            -----END AGE ENCRYPTED FILE-----
-          recipient: age10nd382a9klsn2mrs60emdtsxe43pht3a0m9p29phfrhy0wfyt3vsq9r667
+          recipient: age1njap586hc0q43kr03g6c8eqhdsmk8zcafkl3f83xwlc2gqhlmfgs4tmwad
        - enc: |
            -----BEGIN AGE ENCRYPTED FILE-----
-            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSA3N0hvV01naytDSWVwK1B1
-            MXM1ZkdpaVc2Q3FPV2VBcC83WmcvSjdGUGgwClJGSXZ6YW5JeFlValNJbjVhK29u
-            bUFqN2dRQTI4ZkwyeXNWYk5JeWVJRXcKLS0tIDlMMkNBUnNUSTJwVVFmc2dlcEZS
-            VGQ1VHR2dXB0M3RsalppVWxiUUROM0UKZM/4QDTam3LDTzjnDs41Ije50R7Q7GC4
-            IZbUZjs72rBzY8IkJDbN9JidadEc4NAtMOJwXiJbpZGiCBNfc8+SXw==
+            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSBURHlUL0RNMUtNallEcG5p
+            eG4xby8yVzdQUTBaNkl4ano0YjBMcDd0Wm5NCkZvaXNPZm9wemJkMmNSdGdOaTI4
+            Z1RwUnhiRUpCMWZaeWtlSVBmNW5KOXMKLS0tIDk0R0k3ZHczTFNCWUZxSWF0M0FJ
+            MGlZMmtuSFYrcG1meDNMWDNqSjFxcE0KDu2dAc0gqmmPkpbpBe4YohM7rYmUwEkI
+            V2FUQwjlvh50svtjCVdYbx2xuq4sQLnKelk/q1onLw60FwsVfzD8sQ==
            -----END AGE ENCRYPTED FILE-----
          recipient: age1ll6hj5ggruetgjwjfnplpn5xtq35uhlcdflksx3xmnjm6s3uad9sz70jkf
    lastmodified: "2026-07-19T02:30:40Z"
@@ -26,7 +26,7 @@
  # fresh client that has never manually ssh'd to nix-cache before. Update
  # this if nix-cache's host key is ever rotated or the host is rebuilt
  # from scratch.
-  nixCacheHostKey = "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIHrMKZlIGUd3pH9G3AqbsruqUGjxIXMAZw52u9MwiBCn lxc-nix-cache";
+  nixCacheHostKey = "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIPeWgMsdaiz4axT/deFc1+0B5bN+GX/NOeW9bbQ0c/IT lxc-nix-cache";

  # Public keys authorized to SSH in as remoteBuilderUser on the nix-cache
  # host (modules/nix-cache/server.nix) — one per client host that's allowed
@@ -38,6 +38,7 @@
    "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIIGtOWOCS+ImHc7NehguoyD7PbonGosKMZqc9+QR3v/h root@nixos"
    "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIHxXTQxFnArK5HXG7czeoybZebCGfxpUdusJkPn+BCSp root@server"
    "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAICMJhrfFayLBG+gWtO6oAvgambw5nWWgztiTFEaaaVRH debian@surface"
+    "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIJEj26SL/emsVjW2YhRucJVp2kTz8WgcEQgjBEBLRikk root@claude"
  ];

  # Admin SSH public key, authorized on the primary user of every host and
@@ -137,6 +138,14 @@
    # shortcuts on the gui build type (hosts/nixos/home.nix).
    pveWeb = 8006;
    pbsWeb = 8007;
+
+    # Tor relay's ORPort — the port other Tor relays connect to for onion
+    # routing traffic (modules/tor/enable-relay.nix). Tor's own conventional
+    # default; opened via services.tor.openFirewall rather than
+    # networking.firewall.allowedTCPPorts directly, but kept here anyway so
+    # it's not a bare literal duplicated between the relay's settings and
+    # anything else that ever needs to reference it.
+    torRelayOrPort = 9001;
  };

  # .raw disk image size for every proxmox-* host's standalone Disko image