bao: mint the controller's leaf, and point the controller at it

glue-bao-tls.nix signs a third leaf. It is minted whether or not a
controller runs here, because the case it serves is the one where it
does not: a controller elsewhere needs a leaf from this CA and cannot
sign one, so issuing it here turns "obtain a certificate out of band"
into "copy this file".

glue-controller-bao-identity.nix holds the pairing and nothing else --
which paths this host's controller reads. Gated on the leaf existing
rather than on deploy.bao.enable, so a controller on the store's host
and one three networks away with an out-of-band leaf get the same
wiring; gating on the store would have made the co-located case the
only supported shape. The directory comes from deploy.bao.clientCertFile
rather than repeating glue-bao-tls.nix's literal, so moving the PKI
moves both.

module-eval gains three cases and two fixtures, because nothing asserted
the PKI script before: an earlier commit added a leaf to that rendered
unit and left the derivation unchanged. The fixture's CN is deliberately
a value no default could supply, so "the role and the leaf both carry
it" says they read one option rather than that both happen to say
swarm-controller.

Gates: 62 module properties hold (59 before, plus these three), on a
derivation hash that actually moved -- this suite is a cache hit when
only fixtures change, so an unchanged hash would have meant the cases
never ran. nix fmt clean, all three scripts/check-*.sh exit 0.

nix/host-modules/default.nix

@@ -24,6 +24,7 @@
     ./hive-tls.nix
     ./otel.nix
     ./glue-bao-tls.nix
+    ./glue-controller-bao-identity.nix
     ./glue-matrix-bao-token.nix
     ./swarm-authelia.nix
     ./swarm-bao.nix

nix/host-modules/glue-bao-tls.nix

@@ -16,8 +16,8 @@
 # ⚠️ Not the hive CA and not the swarm CA. The store will eventually
 # distribute both, and an authority you must already hold a certificate from
 # cannot be one the store hands out — reach the store to get the CA material,
-# need a cert from that CA to reach the store. This CA signs exactly two
-# things and distributes nothing, so it cannot enter that cycle.
+# need a cert from that CA to reach the store. This CA signs a fixed, short
+# list of leaves and distributes nothing, so it cannot enter that cycle.
 #
 # ⚠️ Files like this are the only place a `deploy.<foo>` value may derive from
 # a `deploy.<bar>.enable`. Everywhere else that is forbidden. The exception
@@ -126,6 +126,17 @@ in
           ${lib.escapeShellArg cfg.domain} ${lib.escapeShellArg "DNS:${cfg.domain}"} serverAuth
         [ -s ${pkiDir}/client.pem ] || ${signLeaf} ${pkiDir} client \
           ${lib.escapeShellArg clientCn} "" clientAuth
+
+        # Minted whether or not a controller runs here, because the case it
+        # serves is the one where it does not: a controller elsewhere needs a
+        # leaf from this CA and has no way to sign one. Issuing it here turns
+        # "obtain a certificate out of band" into "copy this file".
+        #
+        # Its own CN rather than the reader's above: the controller's policy
+        # lets it create roles for every hive, and the reader's leaf carries
+        # this hive's name.
+        [ -s ${pkiDir}/controller.pem ] || ${signLeaf} ${pkiDir} controller \
+          ${lib.escapeShellArg deployCfg.bao.controllerCommonName} "" clientAuth
       '';
     };
   };

nix/host-modules/glue-controller-bao-identity.nix

@@ -0,0 +1,41 @@
+# Glue: point the swarm controller at the bao leaf minted for it.
+#
+# ONE PAIRING PER FILE — controller ← bao, and nothing else. Deleting this
+# leaves a controller that takes operator-provided certificate paths, which is
+# what every deployment that does not mint its own already does.
+#
+# ⚠️ The minting is NOT here. ./glue-bao-tls.nix holds the CA and signs the
+# leaf, because the thing that owns a private key owns issuing from it; a
+# second signer would duplicate that file's `openssl` helper to no benefit.
+# What belongs here is the pairing: which paths this host's controller reads.
+#
+# ⚠️ Gated on the leaf existing, not on the store being enabled. A controller
+# on the store's own host is one deployment; a controller three networks away
+# holding a leaf issued out of band is another, and both want the same wiring.
+# `deploy.bao.enable` would have made the first one the only supported shape.
+#
+# Everything is `mkDefault`. An operator naming their own paths wins.
+{
+  lib,
+  config,
+  ...
+}:
+let
+  hyperhiveCfg = config.services.hyperhive;
+  deployCfg = hyperhiveCfg.deploy;
+  baoDeploy = deployCfg.bao;
+
+  # Where ./glue-bao-tls.nix puts the leaves. Derived from the reader's own
+  # path rather than repeating that file's directory literal: an operator who
+  # moves the PKI moves both, and the two cannot drift apart.
+  haveMintedPki = baoDeploy.clientCertFile != null;
+  pkiDir = if haveMintedPki then builtins.dirOf baoDeploy.clientCertFile else null;
+in
+{
+  config = lib.mkIf (hyperhiveCfg.enable && deployCfg.swarm-controller.enable && haveMintedPki) {
+    services.hyperhive.deploy.swarm-controller = {
+      baoClientCertFile = lib.mkDefault "${pkiDir}/controller.pem";
+      baoClientKeyFile = lib.mkDefault "${pkiDir}/controller-key.pem";
+    };
+  };
+}