overlays: refactor by using .asFlake attribute

nix/overlays/agenix.nix

@@ -1,9 +1,7 @@
 let
   sources = import ../../npins;
-  inherit (sources) agenix;
-  inherit (agenix.repository) owner repo;
 in
   final: _: {
     # Use flake so the package inputs is pinned
-    agenix = (builtins.getFlake "github:${owner}/${repo}/${agenix.revision}").packages.${final.system}.default;
+    agenix = sources.agenix.asFlake.packages.${final.system}.default;
   }

nix/overlays/disko.nix

@@ -2,7 +2,5 @@ let
   sources = import ../../npins;
 in
   final: _: {
-    disko =
-      final.callPackage (sources.disko + "/package.nix")
-      {diskoVersion = sources.disko.version;};
+    disko = sources.disko.asFlake.packages.${final.system}.default;
   }

nix/overlays/dix.nix

@@ -1,8 +1,6 @@
 let
   sources = import ../../npins;
-  inherit (sources) dix;
-  inherit (dix.repository) owner repo;
 in
   final: _: {
-    dix = (builtins.getFlake "github:${owner}/${repo}/${dix.revision}").packages.${final.system}.default;
+    dix = sources.dix.asFlake.packages.${final.system}.default;
   }

nix/overlays/eepy.nix

@@ -1,8 +1,6 @@
 let
   sources = import ../../npins;
-  inherit (sources) eepy;
-  inherit (eepy.repository) owner repo;
 in
   final: _: {
-    eepy = (builtins.getFlake "github:${owner}/${repo}/${eepy.revision}").packages.${final.system}.default;
+    eepy = sources.eepy.asFlake.packages.${final.system}.default;
   }

nix/overlays/nil.nix

@@ -1,9 +1,22 @@
 # Run the one with my cool feature here for now
 let
   sources = import ../../npins;
-  inherit (sources) nil;
-  inherit (nil.repository) owner repo;
 in
   final: _: {
-    nil = (builtins.getFlake "github:${owner}/${repo}/${nil.revision}").packages.${final.system}.default;
+    nil = let
+      pkg = sources.nil.asFlake.packages.${final.system}.default;
+    in
+      pkg.overrideAttrs (
+        oldAttrs: {
+          patches =
+            oldAttrs.patches or []
+            ++ [
+              (final.fetchpatch {
+                name = "fix-handling-inherit-and-patfield-in-inline-assist";
+                url = "https://github.com/oxalica/nil/pull/178.patch";
+                hash = "sha256-4f7DeWJtt63IyOjqlwzz0f05rv1NBYZO4JWEkFeDimk=";
+              })
+            ];
+        }
+      );
   }

nix/overlays/nur.nix

@@ -1,9 +1,4 @@
 let
   sources = import ../../npins;
 in
-  _: prev: {
-    nur = import sources.nur {
-      nurpkgs = prev;
-      pkgs = prev;
-    };
-  }
+  sources.nur.asFlake.overlays.default