diff --git a/README.md b/README.md
index 8ed3e95..70b6a25 100644
--- a/README.md
+++ b/README.md
@@ -52,6 +52,8 @@ just fmt
 hosts/darwin/   - macOS host entrypoint
 hosts/netty/    - NixOS VPS entrypoint (disko + hardware)
 modules/        - shared system modules + devshells
+modules/hosts/  - flake-parts host output definitions
+modules/nixpkgs.nix - shared flake context (hosts, args, pkgs helpers)
 home/           - Home Manager modules
 lib/hosts.nix   - host metadata used by the flake
 lib/            - shared package sets and theme system
diff --git a/flake.nix b/flake.nix
index a95a5f6..5b340ef 100644
--- a/flake.nix
+++ b/flake.nix
@@ -45,98 +45,13 @@
   };
 
   outputs =
-    inputs@{
-      self,
-      flake-parts,
-      nixpkgs,
-      nix-darwin,
-      home-manager,
-      nix-homebrew,
-      ...
-    }:
-    let
-      username = "rathi";
-      hosts = import ./lib/hosts.nix { inherit username; };
-
-      mkPkgs =
-        system:
-        import nixpkgs {
-          inherit system;
-          config.allowUnfree = true;
-        };
-
-      mkHomeManagerModule =
-        host:
-        {
-          home-manager.useGlobalPkgs = true;
-          home-manager.useUserPackages = true;
-          home-manager.extraSpecialArgs = {
-            inherit inputs self username;
-            hostname = host.hostname;
-          };
-          home-manager.backupFileExtension = "hm-bak";
-          home-manager.users.${username} = import host.homeModule;
-        };
-    in
+    inputs@{ flake-parts, ... }:
     flake-parts.lib.mkFlake { inherit inputs; } {
-      systems = [
-        hosts.darwin.system
-        hosts.netty.system
-      ];
-
       imports = [
+        ./modules/nixpkgs.nix
         ./modules/devshells.nix
+        ./modules/hosts/darwin.nix
+        ./modules/hosts/netty.nix
       ];
-
-      flake = {
-        darwinConfigurations.${hosts.darwin.name} = nix-darwin.lib.darwinSystem {
-          system = hosts.darwin.system;
-          specialArgs = {
-            inherit inputs self username;
-            hostname = hosts.darwin.hostname;
-          };
-          modules = [
-            ./hosts/${hosts.darwin.name}
-            home-manager.darwinModules.home-manager
-            nix-homebrew.darwinModules.nix-homebrew
-            {
-              users.users.${username}.home = hosts.darwin.homeDirectory;
-
-              nix-homebrew = {
-                enable = true;
-                enableRosetta = true;
-                user = username;
-                autoMigrate = true;
-              };
-            }
-            (mkHomeManagerModule hosts.darwin)
-          ];
-        };
-
-        nixosConfigurations.${hosts.netty.name} = nixpkgs.lib.nixosSystem {
-          system = hosts.netty.system;
-          specialArgs = {
-            inherit inputs self username;
-            hostname = hosts.netty.hostname;
-          };
-          modules = [
-            inputs.disko.nixosModules.disko
-            ./hosts/${hosts.netty.name}/configuration.nix
-            home-manager.nixosModules.home-manager
-            (mkHomeManagerModule hosts.netty)
-          ];
-        };
-
-        homeConfigurations.${hosts.netty.name} = home-manager.lib.homeManagerConfiguration {
-          pkgs = mkPkgs hosts.netty.system;
-          extraSpecialArgs = {
-            inherit inputs self username;
-            hostname = hosts.netty.hostname;
-          };
-          modules = [
-            hosts.netty.standaloneHomeModule
-          ];
-        };
-      };
     };
 }
diff --git a/justfile b/justfile
index 8a0c150..ee60ce5 100644
--- a/justfile
+++ b/justfile
@@ -17,7 +17,8 @@ switch config='darwin':
   if [[ "{{config}}" == "darwin" ]]; then
     sudo env PATH="$PATH" nix --extra-experimental-features 'nix-command flakes' run github:nix-darwin/nix-darwin/master#darwin-rebuild -- switch --flake path:.#{{config}}
   else
-    nix --extra-experimental-features 'nix-command flakes' run github:nix-community/home-manager -- switch --flake path:.#{{config}} -b hm-bak
+    backup_ext="hm-bak-$(date +%Y%m%d-%H%M%S)"
+    nix --extra-experimental-features 'nix-command flakes' run github:nix-community/home-manager -- switch --flake path:.#{{config}} -b "$backup_ext"
   fi
 
 fmt:
diff --git a/modules/hosts/darwin.nix b/modules/hosts/darwin.nix
new file mode 100644
index 0000000..12320eb
--- /dev/null
+++ b/modules/hosts/darwin.nix
@@ -0,0 +1,33 @@
+{
+  hosts,
+  inputs,
+  username,
+  mkSpecialArgs,
+  mkHomeManagerModule,
+  ...
+}:
+let
+  host = hosts.darwin;
+in
+{
+  flake.darwinConfigurations.${host.name} = inputs.nix-darwin.lib.darwinSystem {
+    system = host.system;
+    specialArgs = mkSpecialArgs host;
+    modules = [
+      ../../hosts/${host.name}
+      inputs.home-manager.darwinModules.home-manager
+      inputs.nix-homebrew.darwinModules.nix-homebrew
+      {
+        users.users.${username}.home = host.homeDirectory;
+
+        nix-homebrew = {
+          enable = true;
+          enableRosetta = true;
+          user = username;
+          autoMigrate = true;
+        };
+      }
+      (mkHomeManagerModule host)
+    ];
+  };
+}
diff --git a/modules/hosts/netty.nix b/modules/hosts/netty.nix
new file mode 100644
index 0000000..a5d090e
--- /dev/null
+++ b/modules/hosts/netty.nix
@@ -0,0 +1,33 @@
+{
+  hosts,
+  inputs,
+  mkPkgs,
+  mkSpecialArgs,
+  mkHomeManagerModule,
+  ...
+}:
+let
+  host = hosts.netty;
+in
+{
+  flake = {
+    nixosConfigurations.${host.name} = inputs.nixpkgs.lib.nixosSystem {
+      system = host.system;
+      specialArgs = mkSpecialArgs host;
+      modules = [
+        inputs.disko.nixosModules.disko
+        ../../hosts/${host.name}/configuration.nix
+        inputs.home-manager.nixosModules.home-manager
+        (mkHomeManagerModule host)
+      ];
+    };
+
+    homeConfigurations.${host.name} = inputs.home-manager.lib.homeManagerConfiguration {
+      pkgs = mkPkgs host.system;
+      extraSpecialArgs = mkSpecialArgs host;
+      modules = [
+        host.standaloneHomeModule
+      ];
+    };
+  };
+}
diff --git a/modules/nixpkgs.nix b/modules/nixpkgs.nix
new file mode 100644
index 0000000..cbc9007
--- /dev/null
+++ b/modules/nixpkgs.nix
@@ -0,0 +1,45 @@
+{
+  self,
+  inputs,
+  lib,
+  ...
+}:
+let
+  username = "rathi";
+  hosts = import ../lib/hosts.nix { inherit username; };
+
+  mkPkgs =
+    system:
+    import inputs.nixpkgs {
+      inherit system;
+      config.allowUnfree = true;
+    };
+
+  mkSpecialArgs = host: {
+    inherit inputs self username;
+    hostname = host.hostname;
+  };
+
+  mkHomeManagerModule =
+    host:
+    {
+      home-manager.useGlobalPkgs = true;
+      home-manager.useUserPackages = true;
+      home-manager.extraSpecialArgs = mkSpecialArgs host;
+      home-manager.backupCommand = "bash ${../scripts/home-manager-backup.sh}";
+      home-manager.users.${username} = import host.homeModule;
+    };
+in
+{
+  systems = lib.unique (map (host: host.system) (builtins.attrValues hosts));
+
+  _module.args = {
+    inherit
+      username
+      hosts
+      mkPkgs
+      mkSpecialArgs
+      mkHomeManagerModule
+      ;
+  };
+}
diff --git a/scripts/home-manager-backup.sh b/scripts/home-manager-backup.sh
new file mode 100644
index 0000000..f093f91
--- /dev/null
+++ b/scripts/home-manager-backup.sh
@@ -0,0 +1,25 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+if [[ $# -eq 0 ]]; then
+  exit 0
+fi
+
+target_path="${1:?expected target path}"
+base_backup="${target_path}.hm-bak"
+
+if [[ ! -e "$base_backup" ]]; then
+  mv "$target_path" "$base_backup"
+  exit 0
+fi
+
+timestamp="$(date +%Y%m%d-%H%M%S)"
+backup_path="${base_backup}.${timestamp}"
+suffix=0
+
+while [[ -e "$backup_path" ]]; do
+  suffix=$((suffix + 1))
+  backup_path="${base_backup}.${timestamp}.${suffix}"
+done
+
+mv "$target_path" "$backup_path"