diff --git a/.github/workflows/update-flake.yml b/.github/workflows/update-flake.yml
index 3033d148..6194dc1b 100644
--- a/.github/workflows/update-flake.yml
+++ b/.github/workflows/update-flake.yml
@@ -41,22 +41,40 @@ jobs:
             email "$id+$name@users.noreply.github.com" \
             >>"$GITHUB_OUTPUT"
 
-      - uses: DeterminateSystems/update-flake-lock@v26
-        with:
-          token: ${{ steps.generate-token.outputs.token }}
-          git-committer-name: ${{ steps.user-info.outputs.name }}
-          git-committer-email: ${{ steps.user-info.outputs.email }}
-          git-author-name: ${{ steps.user-info.outputs.name }}
-          git-author-email: ${{ steps.user-info.outputs.email }}
-          branch: update_flake_lock_action_${{ matrix.branch }}
-          commit-msg: "flake: update all inputs"
-          pr-title: "${{ startsWith(matrix.branch, 'release') && format('[{0}] ', matrix.branch) || '' }}stylix: update all flake inputs"   # yamllint disable-line rule:line-length
-          pr-labels: "topic: dependencies"
-          pr-body: >
-            Automated changes by the
-            [update-flake-lock](https://github.com/DeterminateSystems/update-flake-lock)
-            GitHub Action.
+      - name: setup git
+        env:
+          name: ${{ steps.user-info.outputs.name }}
+          email: ${{ steps.user-info.outputs.email }}
+        run: |
+          git config --global user.name "$name"
+          git config --global user.email "$email"
 
-            ```
-            {{ env.GIT_COMMIT_MESSAGE }}
-            ```
+      - name: update lock files
+        run: |
+          nix flake update \
+            --commit-lock-file \
+            --option commit-lock-file-summary "flake: update root inputs"
+
+          nix flake update \
+            --commit-lock-file \
+            --flake ./flake/dev \
+            --option commit-lock-file-summary "flake: update dev inputs"
+
+      - name: create pull request
+        env:
+          GH_TOKEN: ${{ steps.generate-token.outputs.token }}
+          base_branch: ${{ matrix.branch }}
+          pr_branch: update_flake_lock_action_${{ matrix.branch }}
+          title: "${{ startsWith(matrix.branch, 'release') && format('[{0}] ', matrix.branch) || '' }}flake: update public and dev inputs"  # yamllint disable-line rule:line-length
+        run: |
+          git switch --create "$pr_branch"
+
+          git push origin "$pr_branch" \
+            --force \
+            --set-upstream
+
+          gh pr create \
+            --base "$base_branch" \
+            --title "$title" \
+            --label "topic: dependencies" ||
+            echo "Failed to create PR"
diff --git a/default.nix b/default.nix
index 4e4468ed..675809c0 100644
--- a/default.nix
+++ b/default.nix
@@ -1,7 +1,7 @@
 (import (
   let
     inherit (lock.nodes.flake-compat.locked) narHash rev;
-    lock = builtins.fromJSON (builtins.readFile ./flake.lock);
+    lock = builtins.fromJSON (builtins.readFile ./flake/dev/flake.lock);
   in
   fetchTarball {
     url = "https://github.com/edolstra/flake-compat/archive/${rev}.tar.gz";
diff --git a/flake.lock b/flake.lock
index da2edfa1..957bf864 100644
--- a/flake.lock
+++ b/flake.lock
@@ -83,21 +83,6 @@
         "type": "github"
       }
     },
-    "flake-compat": {
-      "locked": {
-        "lastModified": 1747046372,
-        "narHash": "sha256-CIVLLkVgvHYbgI2UpXvIIBJ12HWgX+fjA8Xf8PUmqCY=",
-        "owner": "edolstra",
-        "repo": "flake-compat",
-        "rev": "9100a0f413b0c601e0533d1d94ffd501ce2e7885",
-        "type": "github"
-      },
-      "original": {
-        "owner": "edolstra",
-        "repo": "flake-compat",
-        "type": "github"
-      }
-    },
     "flake-parts": {
       "inputs": {
         "nixpkgs-lib": [
@@ -134,51 +119,6 @@
         "type": "github"
       }
     },
-    "git-hooks": {
-      "inputs": {
-        "flake-compat": [
-          "flake-compat"
-        ],
-        "gitignore": "gitignore",
-        "nixpkgs": [
-          "nixpkgs"
-        ]
-      },
-      "locked": {
-        "lastModified": 1747372754,
-        "narHash": "sha256-2Y53NGIX2vxfie1rOW0Qb86vjRZ7ngizoo+bnXU9D9k=",
-        "owner": "cachix",
-        "repo": "git-hooks.nix",
-        "rev": "80479b6ec16fefd9c1db3ea13aeb038c60530f46",
-        "type": "github"
-      },
-      "original": {
-        "owner": "cachix",
-        "repo": "git-hooks.nix",
-        "type": "github"
-      }
-    },
-    "gitignore": {
-      "inputs": {
-        "nixpkgs": [
-          "git-hooks",
-          "nixpkgs"
-        ]
-      },
-      "locked": {
-        "lastModified": 1709087332,
-        "narHash": "sha256-HG2cCnktfHsKV0s4XW83gU3F57gaTljL9KNSuG6bnQs=",
-        "owner": "hercules-ci",
-        "repo": "gitignore.nix",
-        "rev": "637db329424fd7e46cf4185293b9cc8c88c95394",
-        "type": "github"
-      },
-      "original": {
-        "owner": "hercules-ci",
-        "repo": "gitignore.nix",
-        "type": "github"
-      }
-    },
     "gnome-shell": {
       "flake": false,
       "locked": {
@@ -196,26 +136,6 @@
         "type": "github"
       }
     },
-    "home-manager": {
-      "inputs": {
-        "nixpkgs": [
-          "nixpkgs"
-        ]
-      },
-      "locked": {
-        "lastModified": 1751146119,
-        "narHash": "sha256-gvjG95TCnUVJkvQvLMlnC4NqiqFyBdJk3o8/RwuHeaU=",
-        "owner": "nix-community",
-        "repo": "home-manager",
-        "rev": "76d0c31fce2aa0c71409de953e2f9113acd5b656",
-        "type": "github"
-      },
-      "original": {
-        "owner": "nix-community",
-        "repo": "home-manager",
-        "type": "github"
-      }
-    },
     "nixpkgs": {
       "locked": {
         "lastModified": 1748460289,
@@ -263,11 +183,8 @@
         "base16-helix": "base16-helix",
         "base16-vim": "base16-vim",
         "firefox-gnome-theme": "firefox-gnome-theme",
-        "flake-compat": "flake-compat",
         "flake-parts": "flake-parts",
-        "git-hooks": "git-hooks",
         "gnome-shell": "gnome-shell",
-        "home-manager": "home-manager",
         "nixpkgs": "nixpkgs",
         "nur": "nur",
         "systems": "systems",
diff --git a/flake.nix b/flake.nix
index 684dae85..84163b95 100644
--- a/flake.nix
+++ b/flake.nix
@@ -41,16 +41,6 @@
       flake = false;
     };
 
-    flake-compat.url = "github:edolstra/flake-compat";
-
-    git-hooks = {
-      url = "github:cachix/git-hooks.nix";
-      inputs = {
-        flake-compat.follows = "flake-compat";
-        nixpkgs.follows = "nixpkgs";
-      };
-    };
-
     gnome-shell = {
       # TODO: Unlocking the input and pointing to official repository requires
       # updating the patch:
@@ -59,12 +49,6 @@
       flake = false;
     };
 
-    # The 'home-manager' input is used to generate the documentation.
-    home-manager = {
-      url = "github:nix-community/home-manager";
-      inputs.nixpkgs.follows = "nixpkgs";
-    };
-
     nur = {
       url = "github:nix-community/NUR";
       inputs = {
diff --git a/flake/default.nix b/flake/default.nix
index eaef7b99..5fb20f75 100644
--- a/flake/default.nix
+++ b/flake/default.nix
@@ -1,86 +1,21 @@
+{ inputs, lib, ... }:
 {
   imports = [
+    inputs.flake-parts.flakeModules.partitions
     ./deprecation
-    ./dev-shell.nix
     ./modules.nix
     ./packages.nix
-    ./pre-commit.nix
+    ./propagated-packages.nix
   ];
 
-  perSystem =
-    { pkgs, ... }:
-    {
-      # TODO: consider using https://flake.parts/options/treefmt-nix.html once
-      # dev flake is partitioned
-      formatter = pkgs.treefmt.withConfig {
-        runtimeInputs = with pkgs; [
-          # keep-sorted start
-          biome
-          keep-sorted
-          nixfmt-rfc-style
-          ruff
-          stylish-haskell
-          # keep-sorted end
-        ];
+  partitions.dev = {
+    module = ./dev;
+    extraInputsFlake = ./dev;
+  };
 
-        settings = {
-          on-unmatched = "info";
-          tree-root-file = "flake.nix";
-
-          formatter = {
-            # keep-sorted start block=yes
-            biome = {
-              command = "biome";
-              options = [
-                "format"
-                "--write"
-                "--no-errors-on-unmatched"
-                "--config-path"
-                (pkgs.writers.writeJSON "biome.json" {
-                  formatter = {
-                    indentStyle = "space";
-                    indentWidth = 2;
-                    lineWidth = 80;
-                  };
-                })
-              ];
-              includes = [
-                "*.css"
-                "*.js"
-                "*.json"
-              ];
-              excludes = [
-                # Contains custom syntax that biome can't handle
-                "modules/swaync/base.css"
-              ];
-            };
-            keep-sorted = {
-              command = "keep-sorted";
-              includes = [ "*" ];
-            };
-            nixfmt = {
-              command = "nixfmt";
-              options = [ "--width=80" ];
-              includes = [ "*.nix" ];
-            };
-            ruff = {
-              command = "ruff";
-              options = [
-                "--config"
-                (pkgs.writers.writeTOML "ruff.toml" {
-                  line-length = 80;
-                })
-                "format"
-              ];
-              includes = [ "*.py" ];
-            };
-            stylish-haskell = {
-              command = "stylish-haskell";
-              includes = [ "*.hx" ];
-            };
-            # keep-sorted end
-          };
-        };
-      };
-    };
+  partitionedAttrs = lib.genAttrs [
+    "checks"
+    "devShells"
+    "formatter"
+  ] (_: "dev");
 }
diff --git a/flake/dev/default.nix b/flake/dev/default.nix
new file mode 100644
index 00000000..4cc3d37c
--- /dev/null
+++ b/flake/dev/default.nix
@@ -0,0 +1,84 @@
+{
+  imports = [
+    ./dev-shell.nix
+    ./nixpkgs-and-dev-nixpkgs-version-consistency.nix
+    ./packages.nix
+    ./pre-commit.nix
+  ];
+
+  perSystem =
+    { pkgs, ... }:
+    {
+      # TODO: consider using https://flake.parts/options/treefmt-nix.html
+      formatter = pkgs.treefmt.withConfig {
+        runtimeInputs = with pkgs; [
+          # keep-sorted start
+          biome
+          keep-sorted
+          nixfmt-rfc-style
+          ruff
+          stylish-haskell
+          # keep-sorted end
+        ];
+
+        settings = {
+          on-unmatched = "info";
+          tree-root-file = "flake.nix";
+
+          formatter = {
+            # keep-sorted start block=yes
+            biome = {
+              command = "biome";
+              options = [
+                "format"
+                "--write"
+                "--no-errors-on-unmatched"
+                "--config-path"
+                (pkgs.writers.writeJSON "biome.json" {
+                  formatter = {
+                    indentStyle = "space";
+                    indentWidth = 2;
+                    lineWidth = 80;
+                  };
+                })
+              ];
+              includes = [
+                "*.css"
+                "*.js"
+                "*.json"
+              ];
+              excludes = [
+                # Contains custom syntax that biome can't handle
+                "modules/swaync/base.css"
+              ];
+            };
+            keep-sorted = {
+              command = "keep-sorted";
+              includes = [ "*" ];
+            };
+            nixfmt = {
+              command = "nixfmt";
+              options = [ "--width=80" ];
+              includes = [ "*.nix" ];
+            };
+            ruff = {
+              command = "ruff";
+              options = [
+                "--config"
+                (pkgs.writers.writeTOML "ruff.toml" {
+                  line-length = 80;
+                })
+                "format"
+              ];
+              includes = [ "*.py" ];
+            };
+            stylish-haskell = {
+              command = "stylish-haskell";
+              includes = [ "*.hx" ];
+            };
+            # keep-sorted end
+          };
+        };
+      };
+    };
+}
diff --git a/flake/dev-shell.nix b/flake/dev/dev-shell.nix
similarity index 100%
rename from flake/dev-shell.nix
rename to flake/dev/dev-shell.nix
diff --git a/flake/dev/flake.lock b/flake/dev/flake.lock
new file mode 100644
index 00000000..64f1d79d
--- /dev/null
+++ b/flake/dev/flake.lock
@@ -0,0 +1,110 @@
+{
+  "nodes": {
+    "dev-nixpkgs": {
+      "locked": {
+        "lastModified": 1748460289,
+        "narHash": "sha256-7doLyJBzCllvqX4gszYtmZUToxKvMUrg45EUWaUYmBg=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "96ec055edbe5ee227f28cdbc3f1ddf1df5965102",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixpkgs-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "flake-compat": {
+      "locked": {
+        "lastModified": 1747046372,
+        "narHash": "sha256-CIVLLkVgvHYbgI2UpXvIIBJ12HWgX+fjA8Xf8PUmqCY=",
+        "owner": "edolstra",
+        "repo": "flake-compat",
+        "rev": "9100a0f413b0c601e0533d1d94ffd501ce2e7885",
+        "type": "github"
+      },
+      "original": {
+        "owner": "edolstra",
+        "repo": "flake-compat",
+        "type": "github"
+      }
+    },
+    "git-hooks": {
+      "inputs": {
+        "flake-compat": [
+          "flake-compat"
+        ],
+        "gitignore": "gitignore",
+        "nixpkgs": [
+          "dev-nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1747372754,
+        "narHash": "sha256-2Y53NGIX2vxfie1rOW0Qb86vjRZ7ngizoo+bnXU9D9k=",
+        "owner": "cachix",
+        "repo": "git-hooks.nix",
+        "rev": "80479b6ec16fefd9c1db3ea13aeb038c60530f46",
+        "type": "github"
+      },
+      "original": {
+        "owner": "cachix",
+        "repo": "git-hooks.nix",
+        "type": "github"
+      }
+    },
+    "gitignore": {
+      "inputs": {
+        "nixpkgs": [
+          "git-hooks",
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1709087332,
+        "narHash": "sha256-HG2cCnktfHsKV0s4XW83gU3F57gaTljL9KNSuG6bnQs=",
+        "owner": "hercules-ci",
+        "repo": "gitignore.nix",
+        "rev": "637db329424fd7e46cf4185293b9cc8c88c95394",
+        "type": "github"
+      },
+      "original": {
+        "owner": "hercules-ci",
+        "repo": "gitignore.nix",
+        "type": "github"
+      }
+    },
+    "home-manager": {
+      "inputs": {
+        "nixpkgs": [
+          "dev-nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1751146119,
+        "narHash": "sha256-gvjG95TCnUVJkvQvLMlnC4NqiqFyBdJk3o8/RwuHeaU=",
+        "owner": "nix-community",
+        "repo": "home-manager",
+        "rev": "76d0c31fce2aa0c71409de953e2f9113acd5b656",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-community",
+        "repo": "home-manager",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "dev-nixpkgs": "dev-nixpkgs",
+        "flake-compat": "flake-compat",
+        "git-hooks": "git-hooks",
+        "home-manager": "home-manager"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}
diff --git a/flake/dev/flake.nix b/flake/dev/flake.nix
new file mode 100644
index 00000000..214a83e0
--- /dev/null
+++ b/flake/dev/flake.nix
@@ -0,0 +1,54 @@
+{
+  description = ''
+    Private inputs for development purposes. These are used by the top level
+    flake in the `dev` partition, but do not appear in consumers' lock files.
+  '';
+
+  inputs = {
+    # We need to define a nixpkgs input so that other inputs can follow it.
+    # It is prefixed with 'dev-' to avoid shadowing the public flake's
+    # 'nixpkgs' input, which could affect local testing with --override-input.
+    #
+    # TODO: Replace
+    #
+    #           dev-nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
+    #
+    #       with
+    #
+    #           dev-nixpkgs = {
+    #             url = "path:../..";
+    #             inputs = {
+    #               "<PUBLIC_INPUT_1>".follows = "";
+    #               "<PUBLIC_INPUT_2>".follows = "";
+    #               "<PUBLIC_INPUT_3>".follows = "";
+    #             };
+    #           };
+    #
+    #       once 26.05 is released, giving non-flake end-users and Stylix
+    #       contributors two LTS releases to adopt Nix 2.26+ [1]. Note that
+    #       non-nixpkgs public flake inputs should be disabled.
+    #
+    #       [1]: https://github.com/NixOS/nix/blob/d4f67fd46dfe2bc950bdfa14273f87b8a4c32e47/doc/manual/source/release-notes/rl-2.26.md?plain=1#L3-L11
+    dev-nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
+
+    # keep-sorted start block=yes newline_separated=yes
+    flake-compat.url = "github:edolstra/flake-compat";
+
+    git-hooks = {
+      url = "github:cachix/git-hooks.nix";
+      inputs = {
+        flake-compat.follows = "flake-compat";
+        nixpkgs.follows = "dev-nixpkgs";
+      };
+    };
+
+    home-manager = {
+      url = "github:nix-community/home-manager";
+      inputs.nixpkgs.follows = "dev-nixpkgs";
+    };
+    # keep-sorted end
+  };
+
+  # This flake is only used for its inputs.
+  outputs = _: { };
+}
diff --git a/flake/dev/nixpkgs-and-dev-nixpkgs-version-consistency.nix b/flake/dev/nixpkgs-and-dev-nixpkgs-version-consistency.nix
new file mode 100644
index 00000000..56e373be
--- /dev/null
+++ b/flake/dev/nixpkgs-and-dev-nixpkgs-version-consistency.nix
@@ -0,0 +1,24 @@
+{ inputs, ... }:
+{
+  perSystem =
+    { pkgs, ... }:
+    {
+      checks.nixpkgs-and-dev-nixpkgs-version-consistency =
+        pkgs.runCommand "nixpkgs-and-dev-nixpkgs-version-consistency"
+          {
+            dev_nixpkgs = inputs.dev-nixpkgs.narHash;
+            nixpkgs = inputs.nixpkgs.narHash;
+          }
+          ''
+            if [ "$nixpkgs" != "$dev_nixpkgs" ]; then
+              printf \
+                'inconsistent nixpkgs (%s) and dev-nixpkgs (%s) versions\n' \
+                "$nixpkgs" \
+                "$dev_nixpkgs" \
+                >&2
+              exit 1
+            fi
+            mkdir "$out"
+          '';
+    };
+}
diff --git a/flake/dev/packages.nix b/flake/dev/packages.nix
new file mode 100644
index 00000000..bb8aa9b1
--- /dev/null
+++ b/flake/dev/packages.nix
@@ -0,0 +1,18 @@
+{ lib, inputs, ... }:
+{
+  perSystem =
+    { pkgs, config, ... }:
+    {
+      # Build all packages with 'nix flake check' instead of only verifying they
+      # are derivations.
+      checks = config.packages;
+
+      # Testbeds are virtual machines based on NixOS, therefore they are
+      # only available for Linux systems.
+      packages = lib.mkIf pkgs.stdenv.hostPlatform.isLinux (
+        import ../../stylix/testbed/default.nix {
+          inherit pkgs inputs lib;
+        }
+      );
+    };
+}
diff --git a/flake/pre-commit.nix b/flake/dev/pre-commit.nix
similarity index 100%
rename from flake/pre-commit.nix
rename to flake/dev/pre-commit.nix
diff --git a/flake/packages.nix b/flake/packages.nix
index 23005774..88648577 100644
--- a/flake/packages.nix
+++ b/flake/packages.nix
@@ -1,33 +1,19 @@
-{ lib, inputs, ... }:
+{ inputs, ... }:
 {
-
   perSystem =
     { pkgs, config, ... }:
     {
-      # Build all packages with 'nix flake check' instead of only verifying they
-      # are derivations.
-      checks = config.packages;
-
       # Make 'nix run .#doc' serve the documentation site
       apps.doc.program = config.packages.serve-docs;
 
-      packages = lib.mkMerge [
-        # Testbeds are virtual machines based on NixOS, therefore they are
-        # only available for Linux systems.
-        (lib.mkIf pkgs.stdenv.hostPlatform.isLinux (
-          import ../stylix/testbed {
-            inherit pkgs inputs lib;
-          }
-        ))
-        {
-          doc = pkgs.callPackage ../doc {
-            inherit (inputs) self;
-          };
-          serve-docs = pkgs.callPackage ../doc/server.nix {
-            inherit (config.packages) doc;
-          };
-          palette-generator = pkgs.callPackage ../palette-generator { };
-        }
-      ];
+      packages = {
+        doc = pkgs.callPackage ../doc {
+          inherit (inputs) self;
+        };
+        serve-docs = pkgs.callPackage ../doc/server.nix {
+          inherit (config.packages) doc;
+        };
+        palette-generator = pkgs.callPackage ../palette-generator { };
+      };
     };
 }
diff --git a/flake/propagated-packages.nix b/flake/propagated-packages.nix
new file mode 100644
index 00000000..4198c8d5
--- /dev/null
+++ b/flake/propagated-packages.nix
@@ -0,0 +1,24 @@
+{
+  lib,
+  config,
+  partitionStack,
+  ...
+}:
+{
+  # For any output attrs normally defined by the public flake configuration,
+  # any exceptions must be manually propagated from the `dev` partition.
+  #
+  # NOTE: Attrs should be explicitly propagated at the deepest level.
+  # Otherwise the partition won't be lazy, making it pointless.
+  # E.g. propagate `packages.${system}.foo` instead of `packages.${system}`
+  # See: https://github.com/hercules-ci/flake-parts/issues/258
+  perSystem =
+    { pkgs, system, ... }:
+    lib.optionalAttrs (partitionStack == [ ]) {
+      packages = lib.mkIf pkgs.stdenv.hostPlatform.isLinux (
+        lib.mapAttrs (
+          name: _: config.partitions.dev.module.flake.packages.${system}.${name}
+        ) (import ../stylix/testbed/autoload.nix { inherit lib pkgs; })
+      );
+    };
+}