diff --git a/lib/distributed-service/flake-module.nix b/lib/distributed-service/flake-module.nix
index 1169311fa..52f6c7e68 100644
--- a/lib/distributed-service/flake-module.nix
+++ b/lib/distributed-service/flake-module.nix
@@ -14,7 +14,7 @@ in
     }:
     {
       # Run: nix-unit --extra-experimental-features flakes --flake .#legacyPackages.x86_64-linux.<attrName>
-      legacyPackages.evalTest-distributedServices = import ./tests {
+      legacyPackages.evalTests-distributedServices = import ./tests {
         inherit lib self;
       };
 
@@ -24,7 +24,7 @@ in
           nix-unit --eval-store "$HOME" \
             --extra-experimental-features flakes \
             ${inputOverrides} \
-            --flake ${self}#legacyPackages.${system}.evalTest-distributedServices
+            --flake ${self}#legacyPackages.${system}.evalTests-distributedServices
 
           touch $out
         '';
diff --git a/lib/distributed-service/inventory-adapter.nix b/lib/distributed-service/inventory-adapter.nix
index fde7bdfee..d99c1bf74 100644
--- a/lib/distributed-service/inventory-adapter.nix
+++ b/lib/distributed-service/inventory-adapter.nix
@@ -54,7 +54,7 @@ let
         ) [ ] members.tags or [ ]);
     };
 
-  machineHasTag = machineName: tagName: lib.elem tagName inventory.machines.${machineName}.tags;
+  # machineHasTag = machineName: tagName: lib.elem tagName inventory.machines.${machineName}.tags;
 
   # map the instances into the module
   importedModuleWithInstances = lib.mapAttrs (
@@ -119,9 +119,12 @@ let
             machineName:
             let
               machineSettings = instance.roles.${roleName}.machines.${machineName}.settings or { };
-              settingsViaTags = lib.filterAttrs (
-                tagName: _: machineHasTag machineName tagName
-              ) instance.roles.${roleName}.tags;
+              # TODO: tag settings
+              # Wait for this feature until option introspection for 'settings' is done.
+              # This might get too complex to handle otherwise.
+              # settingsViaTags = lib.filterAttrs (
+              #   tagName: _: machineHasTag machineName tagName
+              # ) instance.roles.${roleName}.tags;
             in
             {
               # TODO: Do we want to wrap settings with
@@ -129,7 +132,7 @@ let
               settings = {
                 imports = [
                   machineSettings
-                ] ++ lib.attrValues (lib.mapAttrs (_tagName: v: v.settings) settingsViaTags);
+                ]; # ++ lib.attrValues (lib.mapAttrs (_tagName: v: v.settings) settingsViaTags);
               };
             }
           );
@@ -194,6 +197,10 @@ let
   ) { } evals;
 in
 {
-  inherit importedModuleWithInstances grouped;
-  inherit evals allMachines;
+  inherit
+    importedModuleWithInstances
+    grouped
+    evals
+    allMachines
+    ;
 }
diff --git a/lib/distributed-service/tests/default.nix b/lib/distributed-service/tests/default.nix
index 4ab86e351..7275f8ce3 100644
--- a/lib/distributed-service/tests/default.nix
+++ b/lib/distributed-service/tests/default.nix
@@ -258,70 +258,5 @@ in
     };
 
   per_machine_args = import ./per_machine_args.nix { inherit lib callInventoryAdapter; };
-  # test_per_machine_receives_instances =
-  #   let
-  #     res = callInventoryAdapter {
-  #       # Authored module
-  #       # A minimal module looks like this
-  #       # It isn't exactly doing anything but it's a valid module that produces an output
-  #       modules."A" = {
-  #         _class = "clan.service";
-  #         manifest = {
-  #           name = "network";
-  #         };
-  #         # Define a role without special behavior
-  #         roles.peer = { };
-
-  #         perMachine =
-  #           { instances, ... }:
-  #           {
-  #             nixosModule = instances;
-  #           };
-  #       };
-  #       machines = {
-  #         jon = { };
-  #         sara = { };
-  #       };
-  #       instances."instance_foo" = {
-  #         module = {
-  #           name = "A";
-  #         };
-  #         roles.peer.machines.jon = { };
-  #       };
-  #       instances."instance_bar" = {
-  #         module = {
-  #           name = "A";
-  #         };
-  #         roles.peer.machines.sara = { };
-  #       };
-  #       instances."instance_zaza" = {
-  #         module = {
-  #           name = "B";
-  #         };
-  #         roles.peer.tags.all = { };
-  #       };
-  #     };
-  #   in
-  #   {
-  #     expr = {
-  #       hasMachineSettings =
-  #         res.evals.self-A.config.result.allMachines.jon.nixosModule. # { {instanceName} :: { roles :: { {roleName} :: { machines :: { {machineName} :: { settings :: {} } } } } } }
-  #         instance_foo.roles.peer.machines.jon ? settings;
-  #       machineSettingsEmpty =
-  #         lib.filterAttrs (n: _v: n != "__functor" ) res.evals.self-A.config.result.allMachines.jon.nixosModule. # { {instanceName} :: { roles :: { {roleName} :: { machines :: { {machineName} :: { settings :: {} } } } } } }
-  #         instance_foo.roles.peer.machines.jon.settings;
-  #       hasRoleSettings =
-  #         res.evals.self-A.config.result.allMachines.jon.nixosModule. # { {instanceName} :: { roles :: { {roleName} :: { machines :: { {machineName} :: { settings :: {} } } } } } }
-  #         instance_foo.roles.peer ? settings;
-  #       roleSettingsEmpty =
-  #         lib.filterAttrs (n: _v: n != "__functor" ) res.evals.self-A.config.result.allMachines.jon.nixosModule. # { {instanceName} :: { roles :: { {roleName} :: { machines :: { {machineName} :: { settings :: {} } } } } } }
-  #         instance_foo.roles.peer.settings;
-  #     };
-  #     expected = {
-  #       hasMachineSettings = true;
-  #       machineSettingsEmpty = {};
-  #       hasRoleSettings = true;
-  #       roleSettingsEmpty = {};
-  #     };
-  #   };
+  per_instance_args = import ./per_instance_args.nix { inherit lib callInventoryAdapter; };
 }
diff --git a/lib/distributed-service/tests/per_instance_args.nix b/lib/distributed-service/tests/per_instance_args.nix
new file mode 100644
index 000000000..88394e740
--- /dev/null
+++ b/lib/distributed-service/tests/per_instance_args.nix
@@ -0,0 +1,160 @@
+{ lib, callInventoryAdapter }:
+let
+  # Authored module
+  # A minimal module looks like this
+  # It isn't exactly doing anything but it's a valid module that produces an output
+  modules."A" = {
+    _class = "clan.service";
+    manifest = {
+      name = "network";
+    };
+    # Define two roles with unmergeable interfaces
+    # Both define some 'timeout' but with completely different types.
+    roles.peer.interface =
+      { lib, ... }:
+      {
+        options.timeout = lib.mkOption {
+          type = lib.types.str;
+        };
+      };
+
+    roles.peer.perInstance =
+      {
+        instanceName,
+        settings,
+        machine,
+        ...
+      }:
+      let
+        settings1 = settings {
+          # Sometimes we want to create a default settings set depending on the machine config.
+          # Note: Other machines cannot depend on this settings. We must assign a new name to the settings.
+          # And thus the new value is not accessible by other machines.
+          timeout = lib.mkOverride 10 "config.blah";
+        };
+      in
+      {
+        nixosModule = {
+          inherit instanceName settings machine;
+
+          # We are double vendoring the settings
+          # To test that we can do it indefinitely
+          vendoredSettings = settings1 {
+            # Sometimes we want to create a default settings set depending on the machine config.
+            # Note: Other machines cannot depend on this settings. We must assign a new name to the settings.
+            # And thus the new value is not accessible by other machines.
+            timeout = lib.mkOverride 5 "config.thing";
+          };
+        };
+      };
+  };
+  machines = {
+    jon = { };
+    sara = { };
+  };
+  res = callInventoryAdapter {
+    inherit modules machines;
+    instances."instance_foo" = {
+      module = {
+        name = "A";
+      };
+      roles.peer.machines.jon = {
+        settings.timeout = lib.mkForce "foo-peer-jon";
+      };
+      roles.peer = {
+        settings.timeout = "foo-peer";
+      };
+    };
+    instances."instance_bar" = {
+      module = {
+        name = "A";
+      };
+      roles.peer.machines.jon = {
+        settings.timeout = "bar-peer-jon";
+      };
+    };
+    # import the module "B" (undefined)
+    # All machines have this instance
+    instances."instance_zaza" = {
+      module = {
+        name = "B";
+      };
+      roles.peer.tags.all = { };
+    };
+  };
+
+  filterInternals = lib.filterAttrs (n: _v: !lib.hasPrefix "_" n);
+
+  # Replace internal attributes ('_' prefix)
+  # So we catch their presence but don't check the value
+  mapInternalsRecursive = lib.mapAttrsRecursive (
+    path: v:
+    let
+      name = lib.last path;
+    in
+    if !lib.hasPrefix "_" name then v else name
+  );
+in
+{
+  # settings should evaluate
+  test_per_instance_arguments = {
+    expr = {
+      instanceName =
+        res.evals.self-A.config.result.allRoles.peer.allInstances."instance_foo".allMachines.jon.nixosModule.instanceName;
+
+      # settings are specific.
+      # Below we access:
+      # instance = instance_foo
+      # roles = peer
+      # machines = jon
+      settings = filterInternals res.evals.self-A.config.result.allRoles.peer.allInstances.instance_foo.allMachines.jon.nixosModule.settings;
+      machine = mapInternalsRecursive res.evals.self-A.config.result.allRoles.peer.allInstances.instance_foo.allMachines.jon.nixosModule.machine;
+
+      # hasRoleSettings =
+      #   res.evals.self-A.config.result.allMachines.jon.nixosModule.instance_foo.roles.peer ? settings;
+
+      # # settings are specific.
+      # # Below we access:
+      # # instance = instance_foo
+      # # roles = peer
+      # # machines = *
+      # specificRoleSettings = filterInternals res.evals.self-A.config.result.allMachines.jon.nixosModule.instance_foo.roles.peer.settings;
+    };
+    expected = {
+      instanceName = "instance_foo";
+      settings = {
+        timeout = "foo-peer-jon";
+      };
+      machine = {
+        name = "jon";
+        roles = {
+          peer = {
+            machines = {
+              jon = {
+                settings = {
+                  __functor = "__functor";
+                  timeout = "foo-peer-jon";
+                };
+              };
+            };
+            settings = {
+              __functor = "__functor";
+              timeout = "foo-peer";
+            };
+          };
+        };
+      };
+    };
+  };
+
+  test_per_instance_settings_vendoring = {
+    expr =
+      mapInternalsRecursive
+        res.evals.self-A.config.result.allRoles.peer.allInstances."instance_foo".allMachines.jon.nixosModule.vendoredSettings;
+    expected = {
+      # Returns another override
+      __functor = "__functor";
+      timeout = "config.thing";
+    };
+  };
+}
diff --git a/lib/distributed-service/tests/per_machine_args.nix b/lib/distributed-service/tests/per_machine_args.nix
index ad4784af6..2f5868e3e 100644
--- a/lib/distributed-service/tests/per_machine_args.nix
+++ b/lib/distributed-service/tests/per_machine_args.nix
@@ -1,6 +1,6 @@
 { lib, callInventoryAdapter }:
-
-let # Authored module
+let
+  # Authored module
   # A minimal module looks like this
   # It isn't exactly doing anything but it's a valid module that produces an output
   modules."A" = {