module-eval: pin each swarm-bao reader's ordering after its policy unit

nix/module-eval/bao-grants.nix

@@ -438,6 +438,30 @@ let
           && !(baoGrantHere.containers.swarm-bao.config.systemd.services ? ${unit})
         ) units;
     }
+    {
+      # The other end of those units: each reader logs in against the role its
+      # own policy unit writes, so it has to wait for that unit. Ordering and
+      # never a requirement, since the policy unit skips once the token is gone.
+      name = "each of the four readers is ordered after the unit writing its role";
+      ok =
+        let
+          s = baoGrantWithConsumers.systemd.services;
+          waitsFor =
+            reader:
+            let
+              policy = "${reader}-policy.service";
+            in
+            lib.elem policy s.${reader}.after
+            && lib.elem policy s.${reader}.wants
+            && !(lib.elem policy s.${reader}.requires);
+        in
+        lib.all waitsFor [
+          "swarm-bao-matrix-token"
+          "swarm-bao-queue-agent"
+          "swarm-bao-grafana-oidc"
+          "swarm-bao-otel-oidc"
+        ];
+    }
     {
       # A store host that has not placed a bootstrap token can write no grant at
       # all, so none of the four units may exist — the same claim