From 9b0efa7f3caec944da7ba239ed02bd9cc653323d Mon Sep 17 00:00:00 2001
From: Victor Borja <vborja@apache.org>
Date: Thu, 18 Dec 2025 15:52:17 -0600
Subject: [PATCH] provides merge

---
 .../tests/aspect_merge_duplication.nix        | 75 +++++++++++++++++++
 .../modules/tests/aspect_provides_merge.nix   | 53 +++++++++++++
 2 files changed, 128 insertions(+)
 create mode 100644 checkmate/modules/tests/aspect_merge_duplication.nix
 create mode 100644 checkmate/modules/tests/aspect_provides_merge.nix

diff --git a/checkmate/modules/tests/aspect_merge_duplication.nix b/checkmate/modules/tests/aspect_merge_duplication.nix
new file mode 100644
index 0000000..b769177
--- /dev/null
+++ b/checkmate/modules/tests/aspect_merge_duplication.nix
@@ -0,0 +1,75 @@
+{ lib, targetLib, ... }:
+let
+  flake-aspects-lib = import targetLib lib;
+in
+{
+  # Test demonstrating duplication issue when merging aspect structures
+  # from multiple sources using lib.mkMerge at the module level.
+  #
+  # The problem: when lib.mkMerge combines pre-evaluated aspect structures,
+  # the recursive resolution in resolve.nix processes includes multiple times,
+  # causing multiplicative duplication.
+  #
+  # This reproduces the issue seen in den's namespace.nix where:
+  #   config.den.ful.${name} = lib.mkMerge denfuls;
+  # causes 64x duplication when merging multiple input flakes.
+
+  flake.tests."test mkMerge aspect duplication" =
+    let
+      # Create two separate pre-evaluated aspect scopes
+      inputA = lib.evalModules {
+        modules = [
+          (flake-aspects-lib.new-scope "ns")
+          { ns.aspects.foo.nixos.vals = [ "A" ]; }
+        ];
+      };
+
+      inputB = lib.evalModules {
+        modules = [
+          (flake-aspects-lib.new-scope "ns")
+          { ns.aspects.bar.nixos.vals = [ "B" ]; }
+        ];
+      };
+
+      # Merge using lib.mkMerge - reproduces den namespace.nix pattern
+      merged = lib.evalModules {
+        modules = [
+          (flake-aspects-lib.new-scope "ns")
+          {
+            ns = lib.mkMerge [
+              inputA.config.ns
+              inputB.config.ns
+            ];
+          }
+          {
+            ns.aspects.combined.nixos.vals = [ "C" ];
+            ns.aspects.combined.includes = [
+              merged.config.ns.aspects.foo
+              merged.config.ns.aspects.bar
+            ];
+          }
+        ];
+      };
+
+      # Resolve
+      resolved = merged.config.ns.aspects.combined.modules.nixos;
+      result = lib.evalModules {
+        modules = [
+          resolved
+          { options.vals = lib.mkOption { type = lib.types.listOf lib.types.str; }; }
+        ];
+      };
+
+      allVals = result.config.vals;
+      sortedVals = lib.sort lib.lessThan allVals;
+
+    in
+    {
+      expr = sortedVals;
+      expected = [
+        "A"
+        "B"
+        "C"
+      ];
+    };
+}
diff --git a/checkmate/modules/tests/aspect_provides_merge.nix b/checkmate/modules/tests/aspect_provides_merge.nix
new file mode 100644
index 0000000..8faa9d9
--- /dev/null
+++ b/checkmate/modules/tests/aspect_provides_merge.nix
@@ -0,0 +1,53 @@
+{ lib, targetLib, ... }:
+{
+  flake.tests.test-aspects-merged-provides =
+    let
+      flake-aspects-lib = import targetLib lib;
+
+      first = lib.evalModules {
+        modules = [
+          (flake-aspects-lib.new-scope "foo")
+          (flake-aspects-lib.new-scope "bar")
+          (flake-aspects-lib.new-scope "baz")
+          {
+            foo.aspects.a.provides.b.nixos.x = [ "b" ];
+          }
+          {
+            bar.aspects.a.provides.c.nixos.x = [ "c" ];
+          }
+          (
+            { config, ... }:
+            {
+              bar = config.foo;
+            }
+          )
+          (
+            { config, ... }:
+            {
+              baz.aspects.all.nixos = { };
+              baz.aspects.all.includes = [
+                config.bar.aspects.a._.b
+                config.bar.aspects.a._.c
+              ];
+            }
+          )
+        ];
+      };
+
+      second = lib.evalModules {
+        modules = [
+          first.config.baz.aspects.all.modules.nixos
+          { options.x = lib.mkOption { type = lib.types.listOf lib.types.str; }; }
+        ];
+      };
+
+      expr = lib.sort (a: b: a < b) (lib.unique second.config.x);
+      expected = [
+        "b"
+        "c"
+      ];
+    in
+    {
+      inherit expr expected;
+    };
+}