From 583f2490597f748f83f512b27529ca1986a51d4f Mon Sep 17 00:00:00 2001
From: Jon Seager <jon@sgrs.uk>
Date: Mon, 2 Feb 2026 17:39:38 +0000
Subject: [PATCH] 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 |  40 ++++++++++++++-----
 flake.nix  | 114 +++++++++++++++++++++++------------------------------
 2 files changed, 80 insertions(+), 74 deletions(-)

diff --git a/flake.lock b/flake.lock
index ba98655..c1fcba2 100644
--- a/flake.lock
+++ b/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,
-        "narHash": "sha256-awS2zRgF4uTwrOKwwiJcByDzDOdo3Q1rPZbiHQg/N38=",
-        "owner": "NixOS",
-        "repo": "nixpkgs",
-        "rev": "18dd725c29603f582cf1900e0d25f9f1063dbf11",
+        "lastModified": 1769909678,
+        "narHash": "sha256-cBEymOf4/o3FD5AZnzC3J9hLbiZ+QDT/KDuyHXVJOpM=",
+        "owner": "nix-community",
+        "repo": "nixpkgs.lib",
+        "rev": "72716169fe93074c333e8d0173151350670b824c",
         "type": "github"
       },
       "original": {
-        "owner": "NixOS",
-        "ref": "nixpkgs-unstable",
-        "repo": "nixpkgs",
+        "owner": "nix-community",
+        "repo": "nixpkgs.lib",
         "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,
diff --git a/flake.nix b/flake.nix
index cb8d5a7..6663fbf 100644
--- a/flake.nix
+++ b/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 =
@@ -11,58 +13,21 @@
       self,
       nixpkgs,
       rust-overlay,
-    }:
-    let
-      supportedSystems = [
+      flake-parts,
+    }@inputs:
+    flake-parts.lib.mkFlake { inherit inputs; } {
+      systems = [
         "x86_64-linux"
         "aarch64-linux"
       ];
-      forAllSystems = nixpkgs.lib.genAttrs supportedSystems;
 
-      pkgsForSystem =
-        system:
-        (import nixpkgs {
-          inherit system;
+      perSystem =
+        { config, system, ... }:
+        let
           overlays = [ (import rust-overlay) ];
-        });
-    in
-    {
-      packages = forAllSystems (
-        system:
-        let
-          inherit (pkgsForSystem system)
-            lib
-            rustPlatform
-            ;
+          pkgs = import nixpkgs { inherit system overlays; };
+          inherit (pkgs) lib rustPlatform;
 
-          cargoToml = lib.trivial.importTOML ./Cargo.toml;
-          version = cargoToml.package.version;
-        in
-        rec {
-          default = brewlog;
-
-          brewlog = rustPlatform.buildRustPackage {
-            pname = "brewlog";
-            version = version;
-            src = lib.cleanSource ./.;
-            cargoLock.lockFile = ./Cargo.lock;
-
-            meta = {
-              description = "Log your favourite roasters, roasts, brews and cafes!";
-              homepage = "https://github.com/jnsgruk/brewlog";
-              license = lib.licenses.asl20;
-              mainProgram = "brewlog";
-              platforms = lib.platforms.unix;
-              maintainers = with lib.maintainers; [ jnsgruk ];
-            };
-          };
-        }
-      );
-
-      devShells = forAllSystems (
-        system:
-        let
-          pkgs = pkgsForSystem system;
           rust = pkgs.rust-bin.stable.latest.default.override {
             extensions = [
               "rust-src"
@@ -71,28 +36,49 @@
               "rustfmt"
             ];
           };
+
+          cargoToml = lib.trivial.importTOML ./Cargo.toml;
+          version = cargoToml.package.version;
         in
         {
-          default = pkgs.mkShell {
-            name = "brewlog";
+          packages = {
+            default = self.packages.${system}.brewlog;
 
-            NIX_CONFIG = "experimental-features = nix-command flakes";
-            RUST_SRC_PATH = "${rust}/lib/rustlib/src/rust/library";
+            brewlog = rustPlatform.buildRustPackage {
+              pname = "brewlog";
+              inherit version;
+              src = lib.cleanSource ./.;
+              cargoLock.lockFile = ./Cargo.lock;
 
-            buildInputs =
-              with pkgs;
-              [
-                cargo-watch
-                nil
-                nixfmt
-                sqlite
-                sqlx-cli
-              ]
-              ++ [
-                rust
-              ];
+              meta = {
+                description = "Log your favourite roasters, roasts, brews and cafes!";
+                homepage = "https://github.com/jnsgruk/brewlog";
+                license = lib.licenses.asl20;
+                mainProgram = "brewlog";
+                platforms = lib.platforms.unix;
+                maintainers = with lib.maintainers; [ jnsgruk ];
+              };
+            };
           };
-        }
-      );
+
+          devShells = {
+            default = pkgs.mkShell {
+              name = "brewlog";
+
+              NIX_CONFIG = "experimental-features = nix-command flakes";
+              RUST_SRC_PATH = "${rust}/lib/rustlib/src/rust/library";
+
+              buildInputs =
+                [ rust ]
+                ++ (with pkgs; [
+                  cargo-watch
+                  nil
+                  nixfmt
+                  sqlite
+                  sqlx-cli
+                ]);
+            };
+          };
+        };
     };
 }