diff --git a/aspects/constants.nix b/aspects/constants.nix
new file mode 100644
index 0000000..633cff6
--- /dev/null
+++ b/aspects/constants.nix
@@ -0,0 +1,166 @@
+{ lib, config, ... }:
+
+let
+  # Host submodule type
+  hostType = lib.types.submodule {
+    options = {
+      lanIP = lib.mkOption {
+        type = lib.types.nullOr lib.types.str;
+        default = null;
+        description = "LAN IP address for the host";
+      };
+      tailscaleIP = lib.mkOption {
+        type = lib.types.nullOr lib.types.str;
+        default = null;
+        description = "Tailscale IP address for the host";
+      };
+    };
+  };
+
+  # Service submodule type
+  serviceType = lib.types.submodule {
+    options = {
+      name = lib.mkOption {
+        type = lib.types.str;
+        description = "Service name";
+      };
+      domain = lib.mkOption {
+        type = lib.types.str;
+        description = "Domain name for the service";
+      };
+      host = lib.mkOption {
+        type = lib.types.str;
+        description = "Host where the service runs";
+      };
+      public = lib.mkOption {
+        type = lib.types.bool;
+        default = false;
+        description = "Whether the service is publicly accessible";
+      };
+      lanIP = lib.mkOption {
+        type = lib.types.nullOr lib.types.str;
+        default = null;
+        description = "LAN IP address (inherited from host)";
+      };
+      tailscaleIP = lib.mkOption {
+        type = lib.types.nullOr lib.types.str;
+        default = null;
+        description = "Tailscale IP address (inherited from host)";
+      };
+    };
+  };
+
+  # Raw services list before enrichment
+  rawServices = [
+    {
+      name = "kanidm";
+      domain = "auth.baduhai.dev";
+      host = "alexandria";
+    }
+    {
+      name = "vaultwarden";
+      domain = "pass.baduhai.dev";
+      host = "alexandria";
+    }
+    {
+      name = "forgejo";
+      domain = "git.baduhai.dev";
+      host = "trantor";
+      public = true;
+    }
+    {
+      name = "nextcloud";
+      domain = "cloud.baduhai.dev";
+      host = "alexandria";
+    }
+    {
+      name = "jellyfin";
+      domain = "jellyfin.baduhai.dev";
+      host = "alexandria";
+    }
+  ];
+
+  # Enrich services with host IP information
+  enrichServices = hosts: services:
+    map (svc:
+      let
+        hostInfo = hosts.${svc.host} or {};
+      in
+      svc // {
+        lanIP = hostInfo.lanIP or null;
+        tailscaleIP = hostInfo.tailscaleIP or null;
+      }
+    ) services;
+
+in
+{
+  options.flake = {
+    hosts = lib.mkOption {
+      type = lib.types.attrsOf hostType;
+      default = {};
+      description = "Host definitions with IP addresses";
+    };
+
+    services = lib.mkOption {
+      type = lib.types.listOf serviceType;
+      default = [];
+      description = "Service definitions with enriched host information";
+    };
+
+    lib = lib.mkOption {
+      type = lib.types.attrsOf lib.types.raw;
+      default = {};
+      description = "Utility functions for flake configuration";
+    };
+  };
+
+  config.flake = {
+    hosts = {
+      alexandria = {
+        lanIP = "192.168.15.142";
+        tailscaleIP = "100.76.19.50";
+      };
+      trantor = {
+        tailscaleIP = "100.108.5.90";
+      };
+    };
+
+    services = enrichServices config.flake.hosts rawServices;
+
+    lib = {
+      # Nginx virtual host utilities
+      mkNginxVHosts = { domains }:
+        let
+          mkVHostConfig = domain: vhostConfig:
+            lib.recursiveUpdate {
+              useACMEHost = domain;
+              forceSSL = true;
+              kTLS = true;
+            } vhostConfig;
+        in
+        lib.mapAttrs mkVHostConfig domains;
+
+      # Split DNS utilities for unbound
+      # Generates unbound view config from a list of DNS entries
+      mkSplitDNS = entries:
+        let
+          tailscaleData = map (e: ''"${e.domain}. IN A ${e.tailscaleIP}"'') entries;
+          lanData = map (e: ''"${e.domain}. IN A ${e.lanIP}"'') entries;
+        in
+        [
+          {
+            name = "tailscale";
+            view-first = true;
+            local-zone = ''"baduhai.dev." transparent'';
+            local-data = tailscaleData;
+          }
+          {
+            name = "lan";
+            view-first = true;
+            local-zone = ''"baduhai.dev." transparent'';
+            local-data = lanData;
+          }
+        ];
+    };
+  };
+}