refactor(nix): migrate flake.nix to flake-parts

- Replace manual forAllSystems pattern with flake-parts.lib.mkFlake
- Use perSystem for packages and devShells definitions
- Pin rust-overlay's nixpkgs to follow main nixpkgs input
- No functional changes to package or dev shell

flake.lock

@@ -1,5 +1,23 @@
 {
   "nodes": {
+    "flake-parts": {
+      "inputs": {
+        "nixpkgs-lib": "nixpkgs-lib"
+      },
+      "locked": {
+        "lastModified": 1769996383,
+        "narHash": "sha256-AnYjnFWgS49RlqX7LrC4uA+sCCDBj0Ry/WOJ5XWAsa0=",
+        "owner": "hercules-ci",
+        "repo": "flake-parts",
+        "rev": "57928607ea566b5db3ad13af0e57e921e6b12381",
+        "type": "github"
+      },
+      "original": {
+        "owner": "hercules-ci",
+        "repo": "flake-parts",
+        "type": "github"
+      }
+    },
     "nixpkgs": {
       "locked": {
         "lastModified": 1763283776,
@@ -16,31 +34,33 @@
         "type": "github"
       }
     },
-    "nixpkgs_2": {
+    "nixpkgs-lib": {
       "locked": {
-        "lastModified": 1744536153,
+        "lastModified": 1769909678,
-        "narHash": "sha256-awS2zRgF4uTwrOKwwiJcByDzDOdo3Q1rPZbiHQg/N38=",
+        "narHash": "sha256-cBEymOf4/o3FD5AZnzC3J9hLbiZ+QDT/KDuyHXVJOpM=",
-        "owner": "NixOS",
+        "owner": "nix-community",
-        "repo": "nixpkgs",
+        "repo": "nixpkgs.lib",
-        "rev": "18dd725c29603f582cf1900e0d25f9f1063dbf11",
+        "rev": "72716169fe93074c333e8d0173151350670b824c",
         "type": "github"
       },
       "original": {
-        "owner": "NixOS",
+        "owner": "nix-community",
-        "ref": "nixpkgs-unstable",
+        "repo": "nixpkgs.lib",
-        "repo": "nixpkgs",
         "type": "github"
       }
     },
     "root": {
       "inputs": {
+        "flake-parts": "flake-parts",
         "nixpkgs": "nixpkgs",
         "rust-overlay": "rust-overlay"
       }
     },
     "rust-overlay": {
       "inputs": {
-        "nixpkgs": "nixpkgs_2"
+        "nixpkgs": [
+          "nixpkgs"
+        ]
       },
       "locked": {
         "lastModified": 1763433504,

flake.nix

@@ -4,6 +4,8 @@
   inputs = {
     nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
     rust-overlay.url = "github:oxalica/rust-overlay";
+    rust-overlay.inputs.nixpkgs.follows = "nixpkgs";
+    flake-parts.url = "github:hercules-ci/flake-parts";
   };
 
   outputs =
@@ -11,39 +13,40 @@
       self,
       nixpkgs,
       rust-overlay,
-    }:
+      flake-parts,
-    let
+    }@inputs:
-      supportedSystems = [
+    flake-parts.lib.mkFlake { inherit inputs; } {
+      systems = [
         "x86_64-linux"
         "aarch64-linux"
       ];
-      forAllSystems = nixpkgs.lib.genAttrs supportedSystems;
 
-      pkgsForSystem =
+      perSystem =
-        system:
+        { config, system, ... }:
-        (import nixpkgs {
-          inherit system;
-          overlays = [ (import rust-overlay) ];
-        });
-    in
-    {
-      packages = forAllSystems (
-        system:
         let
-          inherit (pkgsForSystem system)
+          overlays = [ (import rust-overlay) ];
-            lib
+          pkgs = import nixpkgs { inherit system overlays; };
-            rustPlatform
+          inherit (pkgs) lib rustPlatform;
-            ;
+
+          rust = pkgs.rust-bin.stable.latest.default.override {
+            extensions = [
+              "rust-src"
+              "clippy"
+              "rust-analyzer"
+              "rustfmt"
+            ];
+          };
 
           cargoToml = lib.trivial.importTOML ./Cargo.toml;
           version = cargoToml.package.version;
         in
-        rec {
+        {
-          default = brewlog;
+          packages = {
+            default = self.packages.${system}.brewlog;
 
             brewlog = rustPlatform.buildRustPackage {
               pname = "brewlog";
-            version = version;
+              inherit version;
               src = lib.cleanSource ./.;
               cargoLock.lockFile = ./Cargo.lock;
 
@@ -56,23 +59,9 @@
                 maintainers = with lib.maintainers; [ jnsgruk ];
               };
             };
-        }
-      );
-
-      devShells = forAllSystems (
-        system:
-        let
-          pkgs = pkgsForSystem system;
-          rust = pkgs.rust-bin.stable.latest.default.override {
-            extensions = [
-              "rust-src"
-              "clippy"
-              "rust-analyzer"
-              "rustfmt"
-            ];
           };
-        in
+
-        {
+          devShells = {
             default = pkgs.mkShell {
               name = "brewlog";
 
@@ -80,19 +69,16 @@
               RUST_SRC_PATH = "${rust}/lib/rustlib/src/rust/library";
 
               buildInputs =
-              with pkgs;
+                [ rust ]
-              [
+                ++ (with pkgs; [
                   cargo-watch
                   nil
                   nixfmt
                   sqlite
                   sqlx-cli
-              ]
+                ]);
-              ++ [
+            };
-                rust
+          };
-              ];
         };
-        }
-      );
     };
 }