deploy: separate "what this host deploys" from swarm-wide truth

`services.hyperhive.swarm.*` is meant to be identical on every host in a
swarm — it describes the swarm, and every hive needs all of it to be a
client. But it also carried the `enable` toggles, which are precisely the
values that must differ per machine. The namespace that should be the
same everywhere held the one thing that cannot be.

Adds `services.hyperhive.deploy.*` for a host's deployment decisions, and
moves the first of them (`swarm.grafana.enable` -> `deploy.grafana`) as
the pattern for the rest. Flat and named for the thing deployed rather
than grouped under a "swarm services" attribute: from the deploy side it
does not matter what kind of thing each one is, and a grouping by service
kind would re-encode the service-side taxonomy into a layer that does not
care about it.

Behaviour is unchanged. The move is a rename in the strict sense — same
type, same meaning, new path — so `mkRenamedOptionModule` carries it and
existing configs keep evaluating with one warning naming both paths. The
renames live in the new module rather than the service modules, so the
whole migration has a single home and a single file to delete when the
deprecation window closes.

nix/host-modules/default.nix

@@ -12,6 +12,7 @@
 {
   imports = [
     ./hyperhive.nix
+    ./deploy.nix
     ./local-defaults.nix
     ./hive-c0re
     ./hive-ci.nix

nix/host-modules/deploy.nix

@@ -0,0 +1,53 @@
+# "What does THIS host deploy?"
+#
+# Separated from `services.hyperhive.swarm.*` because those are two
+# different kinds of fact and only one of them varies per machine:
+#
+#   swarm.*   — swarm-wide truth. The swarm's name, domain, hives, peers,
+#               CA, and where each service lives. **Identical on every
+#               host**, byte for byte; a hive needs all of it to be a
+#               *client* of the swarm.
+#   deploy.*  — this machine's deployment decisions. Necessarily different
+#               on every host, because that is what a deployment is.
+#
+# The `enable` toggles used to live under `swarm.*`, which made the
+# namespace that is supposed to be identical everywhere carry the one
+# thing that must differ.
+#
+# Flat and named for the thing deployed — `deploy.forgejo`, not
+# `deploy.swarmServices.forgejo`. Grouping by "swarm service" would
+# re-encode the service-side taxonomy into a layer that does not care
+# about it: from here, a host deploys forgejo, or a hive, or the lot, and
+# what *kind* of thing each one is belongs to the service module.
+#
+# ⚠️ The renames below are deliberately in this one file rather than
+# spread across the service modules, so the whole move has a single home
+# and a single file to delete when the deprecation window closes — the
+# shape ./swarm-peers-removed.nix already uses.
+{ lib, ... }:
+{
+  imports = [
+    # Same type, same meaning, new path — so a rename carries it exactly
+    # and existing configs keep evaluating with one warning naming both
+    # paths. Precedent: ./hive-forge/default.nix, ./hive-matrix.nix.
+    (lib.mkRenamedOptionModule
+      [ "services" "hyperhive" "swarm" "grafana" "enable" ]
+      [ "services" "hyperhive" "deploy" "grafana" ]
+    )
+  ];
+
+  options.services.hyperhive.deploy = {
+    grafana = lib.mkOption {
+      type = lib.types.bool;
+      default = false;
+      description = ''
+        Run the swarm's metrics UI on this host.
+
+        Off by default and not derived from
+        {option}`services.hyperhive.enable`: a swarm has one Grafana, so
+        running it is a decision about this host rather than about
+        whether hyperhive is installed.
+      '';
+    };
+  };
+}

nix/host-modules/swarm-grafana.nix

@@ -16,6 +16,7 @@
 }:
 let
   cfg = config.services.hyperhive.swarm.grafana;
+  deployCfg = config.services.hyperhive.deploy;
   networkCfg = config.services.hyperhive.network;
   hyperhiveCfg = config.services.hyperhive;
   gatewayCfg = hyperhiveCfg.gateway;
@@ -106,18 +107,12 @@ let
 
 in
 {
+  # `enable` moved to `services.hyperhive.deploy.grafana` — see
+  # ./deploy.nix. Whether this host runs the swarm's Grafana is a
+  # deployment decision, and `swarm.*` has to be identical on every host.
+  # What stays here is what the service IS: its package, domain, and
+  # wiring.
   options.services.hyperhive.swarm.grafana = {
-    enable = lib.mkOption {
-      type = lib.types.bool;
-      default = false;
-      description = ''
-        Run the swarm's metrics UI on this host. Off by default and not
-        derived from {option}`services.hyperhive.enable`: a swarm has one
-        Grafana, so enabling it is a decision about swarm topology rather
-        than about whether hyperhive is installed.
-      '';
-    };
-
     package = lib.mkOption {
       type = lib.types.package;
       default = pkgs.grafana;
@@ -312,8 +307,8 @@ in
     };
   };
 
-  config = lib.mkIf (hyperhiveCfg.enable && cfg.enable) {
-    # The gateway name and the quick-link, both inside `cfg.enable` — that
+  config = lib.mkIf (hyperhiveCfg.enable && deployCfg.grafana) {
+    # The gateway name and the quick-link, both inside `deploy.grafana` — that
     # guard is the load-bearing part. Every hive in a swarm may know this UI
     # exists, but only the host that RUNS it may claim the name; a client
     # hive declaring the vhost would answer for a service it does not have.

nix/host-modules/swarm-required-services.nix

@@ -69,7 +69,8 @@ in
     # takes one and not the other from this switch. An operator who wants
     # exactly one still sets it directly, which `mkDefault` allows.
     victoriametrics.enable = lib.mkDefault swarmCfg.enableRequiredServices;
-    grafana.enable = lib.mkDefault swarmCfg.enableRequiredServices;
+    # (grafana's half of the pair derives below — it lives in `deploy.*`
+    # now, which is a different attribute path, not a different rule.)
 
     # The log store, deriving from the same switch for the same reason —
     # and deliberately in the same commit as the collector pipeline that
@@ -88,4 +89,10 @@ in
   # The collector that feeds the pair above (note: no `swarm.` prefix,
   # this is ./otel.nix's existing per-hive option).
   config.services.hyperhive.otel.enable = lib.mkDefault swarmCfg.enableRequiredServices;
+
+  # Grafana, the UI half of the metrics pair. Same derivation and the same
+  # reasoning as `victoriametrics.enable` above; it reads differently only
+  # because "does this host run it" now lives in `deploy.*` (./deploy.nix)
+  # rather than under `swarm.*`, which has to be identical on every host.
+  config.services.hyperhive.deploy.grafana = lib.mkDefault swarmCfg.enableRequiredServices;
 }

nix/host-modules/swarm.nix

@@ -23,6 +23,7 @@
 let
   cfg = config.services.hyperhive;
   swarmCfg = cfg.swarm;
+  deployCfg = cfg.deploy;
 
   # Public hostnames of the swarm's own services, in declaration order.
   # `serviceDomains` below is this set sorted + deduplicated.
@@ -57,7 +58,7 @@ let
   # metrics UI and store looked fine for as long as only people opened
   # them; the collector's exporter — same defect, no human in the loop —
   # failed every POST and dropped the samples.
-  ++ lib.optional swarmCfg.grafana.enable swarmCfg.grafana.domain
+  ++ lib.optional deployCfg.grafana swarmCfg.grafana.domain
   ++ lib.optional swarmCfg.victoriametrics.enable swarmCfg.victoriametrics.domain
   ++ lib.optional swarmCfg.otel.enable swarmCfg.otel.domain
   # VictoriaLogs' vhost is new (was previously unpublished entirely — see