flake/dev/diff-plugins: make a package output

Allow running from the flake lock.

Author: khaneliman

flake/dev/default.nix

@@ -2,6 +2,7 @@
 {
   imports = [
     ./devshell.nix
+    ./diff-plugins
     ./list-plugins
     ./package-tests.nix
     ./template-tests.nix

flake/dev/devshell.nix

@@ -115,11 +115,6 @@
               command = ''${./new-plugin.py} "$@"'';
               help = "Create a new plugin";
             }
-            {
-              name = "diff-plugins";
-              command = ''${./diff-plugins.py} "$@"'';
-              help = "Compare available plugins with another nixvim commit";
-            }
           ];
       };
     };

flake/dev/diff-plugins/default.nix

@@ -0,0 +1,30 @@
+{
+  perSystem =
+    {
+      lib,
+      pkgs,
+      ...
+    }:
+    let
+      package = pkgs.writers.writePython3Bin "diff-plugins" {
+        # Disable flake8 checks that are incompatible with the ruff ones
+        flakeIgnore = [
+          # Thinks shebang is a block comment
+          "E265"
+          # line too long
+          "E501"
+        ];
+      } (builtins.readFile ./diff-plugins.py);
+    in
+    {
+      packages.diff-plugins = package;
+
+      devshells.default.commands = [
+        {
+          name = "diff-plugins";
+          command = ''${lib.getExe package} "$@"'';
+          help = "Compare available plugins with another nixvim commit";
+        }
+      ];
+    };
+}