Implement allowing to specific stable packages to be added to system packages

flake.lock

@@ -182,6 +182,22 @@
         "type": "github"
       }
     },
+    "nixpkgs-stable_2": {
+      "locked": {
+        "lastModified": 1732053737,
+        "narHash": "sha256-A+F7WSHR29wIynmzbXMwgUb9rkNAeYwlN15Xm3vZjKk=",
+        "owner": "nixos",
+        "repo": "nixpkgs",
+        "rev": "32754128c4ef529c567d216a783cb6fdd95ff196",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nixos",
+        "ref": "release-24.05",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
     "nixpkgs_2": {
       "locked": {
         "lastModified": 1731676054,
@@ -203,7 +219,8 @@
         "home-manager": "home-manager",
         "niri": "niri",
         "nixd": "nixd",
-        "nixpkgs": "nixpkgs_2"
+        "nixpkgs": "nixpkgs_2",
+        "nixpkgs-stable": "nixpkgs-stable_2"
       }
     },
     "treefmt-nix": {

flake.nix

@@ -3,6 +3,7 @@
 
   inputs = {
     nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
+    nixpkgs-stable.url = "github:nixos/nixpkgs/release-24.05";
 
     home-manager = {
       url = "github:nix-community/home-manager";

global.nix

@@ -13,7 +13,14 @@
 
   services.flatpak.enable = true;
 
-  environment.systemPackages = with pkgs; [
+  environment.systemPackages = let 
+  	# You can specify here if you want to add any packages from the stable branch onto your system
+	stablePackages = with inputs.nixpkgs-stable.legacyPackages.x86_64-linux; [
+	  gtk-pipe-viewer
+	];
+  in
+  	# Normal (unstable) packages
+  	with pkgs; [
   	  nix-index
   	  git
 
@@ -72,7 +79,8 @@
   	  linuxPackages.usbip
   	  unixtools.xxd
   	  dotnet-sdk
-  ];
+  	] ++ stablePackages;
+
   systemd.services.usbipd = {
     description = "Custom service that runs usbipd";
     wantedBy = [ "multi-user.target" ];