fix(#3343): move the all-local queue derivations into the deployment mode

Review point: the co-located defaults are an auto-deploy special case and
belong with the other ones, not inside each option's own default. An
option should describe itself; the mode describes what a deployment shape
implies. local-defaults.nix already says exactly this in its header.

Options now default to empty (= unset, which the assertions refuse), and
enableAllLocalDefaults fills in loopback + the minted secret path.

nix/host-modules/local-defaults.nix

@@ -88,5 +88,33 @@ in
     # instead would be wrong: a hive in a larger swarm can legitimately
     # want the shared services without being the host that controls them.
     controller.enable = lib.mkDefault cfg.enableAllLocalDefaults;
+
+    # The controller's queue coordinates. Co-location is what makes these
+    # derivable at all — loopback only reaches the queue when the queue is
+    # here, and the minted client secret only exists on the host authelia
+    # ran its first boot on — so they belong to the mode that asserts this
+    # box is the whole deployment, not to the options' own `default`.
+    #
+    # Deriving them from `swarm.nats.enable` / `swarm.authelia.enable`
+    # inside those defaults is the mixing this file exists to prevent: the
+    # option would be describing a deployment shape instead of describing
+    # itself, and "what does all-local turn on?" would stop having one
+    # answer.
+    #
+    # ⚠️ Must live INSIDE this attrset, not as a second
+    # `config.services.hyperhive.swarm.…` path beside it — written that
+    # way the two definitions of `swarm` collide and the nested one is
+    # silently lost. The gate caught exactly that: mode on, `natsUrl`
+    # still "".
+    #
+    # The *requirement* stays in `swarm-controller.nix` as an assertion:
+    # needing a queue is the controller's own property in every topology,
+    # and only the convenience is local.
+    controller.queue.natsUrl = lib.mkIf cfg.enableAllLocalDefaults (
+      lib.mkDefault "nats://127.0.0.1:${toString config.services.hyperhive.swarm.nats.port}"
+    );
+    controller.queue.clientSecretFile = lib.mkIf cfg.enableAllLocalDefaults (
+      lib.mkDefault "${config.services.hyperhive.swarm.authelia.hostClientSecretDir}/swarm-controller.secret"
+    );
   };
 }

nix/host-modules/swarm-controller.nix

@@ -189,19 +189,19 @@ in
     queue = {
       natsUrl = lib.mkOption {
         type = lib.types.str;
-        default = lib.optionalString natsCfg.enable "nats://127.0.0.1:${toString natsCfg.port}";
+        default = "";
-        defaultText = lib.literalExpression ''
-          if swarm.nats.enable then "nats://127.0.0.1:''${toString swarm.nats.port}" else ""
-        '';
         example = "nats://queue.example.com:4222";
         description = ''
           Where the controller reaches the swarm queue.
 
-          Defaults to loopback when this host runs the queue — the queue
+          Empty means unset, which the assertion below refuses — a
-          container shares the host netns, so that address is correct
+          controller with no queue is not a lighter controller.
-          here and is not the `localhost`-means-the-agent trap that
+
-          applies inside agent containers. Set it explicitly when the
+          `enableAllLocalDefaults` fills this in with loopback, because
-          queue lives elsewhere.
+          that address is only correct when the queue is on this host:
+          its container shares the host netns. That derivation lives with
+          the mode rather than here, so this option describes itself
+          rather than a deployment shape.
         '';
       };
 
@@ -221,20 +221,18 @@ in
 
       clientSecretFile = lib.mkOption {
         type = lib.types.str;
-        default = lib.optionalString autheliaCfg.enable "${autheliaCfg.hostClientSecretDir}/${queueClientId}.secret";
+        default = "";
-        defaultText = lib.literalExpression ''
-          "''${swarm.authelia.hostClientSecretDir}/swarm-controller.secret"
-        '';
         example = "/var/lib/secrets/swarm-controller-queue.secret";
         description = ''
           Path on **this** host holding the plaintext of the controller's
           OAuth2 client secret. A path, never a value: the secret would
           otherwise land in the world-readable nix store.
 
-          Defaults to the file authelia's first-boot generator mints when
+          The controller cannot mint its own — minting happens inside
-          authelia runs here. When it doesn't, the operator places the
+          authelia's state directory during its first boot — so away from
-          secret and names it — the controller cannot mint its own,
+          that host the operator places the secret and names it here.
-          because minting happens inside authelia's state directory.
+          `enableAllLocalDefaults` points this at the minted file, which
+          is exactly the case where one exists locally.
 
           Read by `LoadCredential`, so it needs to be readable by root at
           unit start and nothing more; the daemon's own user never sees