diff --git a/Justfile b/Justfile
new file mode 100644
index 0000000..8588f0e
--- /dev/null
+++ b/Justfile
@@ -0,0 +1,14 @@
+help:
+  just -l
+
+docs:
+  cd docs && pnpm run dev
+
+ci test="":
+  nix-unit  --override-input target . --flake github:vic/checkmate#.tests.systems.x86_64-linux.system-agnostic.{{test}}
+  
+check:
+  nix flake check  --override-input target . github:vic/checkmate
+
+fmt:
+  nix run github:vic/checkmate#fmt --override-input target .
diff --git a/checkmate/modules/formatter.nix b/checkmate/modules/formatter.nix
index c5348fb..ee77886 100644
--- a/checkmate/modules/formatter.nix
+++ b/checkmate/modules/formatter.nix
@@ -1,4 +1,7 @@
 {
   perSystem.treefmt.programs.nixf-diagnose.enable = false;
-  perSystem.treefmt.settings.global.excludes = [ "docs/*" ];
+  perSystem.treefmt.settings.global.excludes = [
+    "docs/*"
+    "Justfile"
+  ];
 }
diff --git a/nix/forward.nix b/nix/forward.nix
index 7fa8e9a..66459b6 100644
--- a/nix/forward.nix
+++ b/nix/forward.nix
@@ -1,4 +1,3 @@
-lib:
 # An utility for creating new aspect configuration classes that
 # help with separation of concerns.
 #
@@ -39,6 +38,7 @@ lib:
 #
 # See checkmate/modules/tests/forward.nix for working example.
 #
+lib:
 {
   each,
   fromClass,
@@ -47,6 +47,7 @@ lib:
   fromAspect,
 }:
 let
+  resolve = import ./resolve.nix lib;
   include =
     item:
     let
@@ -54,7 +55,7 @@ let
       into = intoClass item;
       path = intoPath item;
       aspect = fromAspect item;
-      module = aspect.resolve { class = from; };
+      module = resolve from [ ] aspect;
       config = lib.setAttrByPath path (
         { ... }:
         {
diff --git a/nix/lib.nix b/nix/lib.nix
index 58b03fc..a598371 100644
--- a/nix/lib.nix
+++ b/nix/lib.nix
@@ -1,27 +1,15 @@
-# Public API entry point for flake-aspects library
-# Exports: types, transpose, aspects, new, new-scope
 lib:
 let
-  # Type system: aspectsType, aspectSubmodule, providerType
   types = import ./types.nix lib;
-
-  # Generic transposition utility: parameterized by emit function
+  resolve = import ./resolve.nix lib;
   transpose =
     {
       emit ? lib.singleton,
     }:
     import ./default.nix { inherit lib emit; };
-
-  # Aspect transposition with resolution
   aspects = import ./aspects.nix lib;
-
-  # Dynamic class forwarding into submodules
   forward = import ./forward.nix lib;
-
-  # Low-level scope factory: parameterized by callback
   new = import ./new.nix lib;
-
-  # High-level named scope factory
   new-scope = import ./new-scope.nix new;
 in
 {
@@ -32,5 +20,6 @@ in
     new
     new-scope
     forward
+    resolve
     ;
 }
diff --git a/nix/resolve.nix b/nix/resolve.nix
index cab0660..857d6e1 100644
--- a/nix/resolve.nix
+++ b/nix/resolve.nix
@@ -1,18 +1,13 @@
-# Core aspect resolution algorithm
-# Resolves aspect definitions into nixpkgs modules with dependency resolution
-
 lib:
 let
-  # Process a single provider: invoke with context and resolve
   include =
     class: aspect-chain: provider:
     let
-      provided = provider { inherit aspect-chain class; };
+      provided = if lib.isFunction provider then provider { inherit aspect-chain class; } else provider;
     in
-    resolve class aspect-chain provided;
+    inner class aspect-chain provided;
 
-  # Main resolution: extract class config and recursively resolve includes
-  resolve = class: aspect-chain: provided: {
+  inner = class: aspect-chain: provided: {
     imports =
       let
         config = provided.${class} or { };
@@ -24,5 +19,18 @@ let
       ];
   };
 
+  resolve =
+    class: aspect-chain: aspect:
+    let
+      provided =
+        if lib.isFunction aspect then
+          aspect {
+            inherit class;
+            aspect-chain = aspect-chain;
+          }
+        else
+          aspect;
+    in
+    inner class aspect-chain provided;
 in
 resolve
diff --git a/nix/types.nix b/nix/types.nix
index 454b998..3c2b1a2 100644
--- a/nix/types.nix
+++ b/nix/types.nix
@@ -1,10 +1,7 @@
-# Core type system for aspect-oriented configuration
-
 lib:
 let
   resolve = import ./resolve.nix lib;
 
-  # Type for computed values that only exist during evaluation
   ignoredType = lib.types.mkOptionType {
     name = "ignored type";
     description = "ignored values";
@@ -24,48 +21,39 @@ let
       apply = fn;
     };
 
-  # Like lib.types.functionTo, but it does not merges all definitions, and keeps
-  # just the last one.
-  functorType = lib.mkOptionType {
+  functorType = lib.types.mkOptionType {
     name = "aspectFunctor";
     description = "aspect functor function";
     check = lib.isFunction;
     merge =
-      loc: defs:
+      _loc: defs:
       let
-        # Use only the last definition to avoid duplication from
-        # functionTo merging all definitions with the same args.
-        # All definitions receive the same merged `self`, so they
-        # produce equivalent results - picking one is correct.
         lastDef = lib.last defs;
-        innerType = providerType;
       in
       {
         __functionArgs = lib.functionArgs lastDef.value;
         __functor =
           _: callerArgs:
-          (lib.modules.mergeDefinitions (loc ++ [ "<function body>" ]) innerType [
-            {
-              inherit (lastDef) file;
-              value = lastDef.value callerArgs;
-            }
-          ]).mergedValue;
+          let
+            result = lastDef.value callerArgs;
+          in
+          if builtins.isFunction result then result else _: result;
       };
   };
 
-  # Check if function has submodule-style arguments
   isSubmoduleFn =
     m:
-    lib.length (
-      lib.intersectLists [ "lib" "config" "options" "aspect" ] (lib.attrNames (lib.functionArgs m))
-    ) > 0;
+    let
+      args = lib.functionArgs m;
+    in
+    args ? lib || args ? config || args ? options || args ? aspect;
 
   # Check if function accepts { class } and/or { aspect-chain }
   isProviderFn =
     f:
     let
       args = lib.functionArgs f;
-      n = lib.length (lib.attrNames args);
+      n = builtins.length (builtins.attrNames args);
     in
     (args ? class && n == 1)
     || (args ? aspect-chain && n == 1)