Pin CI tools with a flake

Also includes a .prettierrc, since later versions default to a single quote, which isn't the repo's style.

.github/workflows/validate.yml

@@ -17,8 +17,8 @@ jobs:
         with:
           determinate: true
       - uses: DeterminateSystems/flakehub-cache-action@main
-      - run: nix run nixpkgs#action-validator -- -v ./.github/workflows/workflow.yml
-      - run: nix run nixpkgs#nodePackages.prettier -- --check .
+      - run: nix develop -c action-validator -v ./.github/workflows/workflow.yml
+      - run: nix develop -c prettier --check .
 
   DeterminateCI:
     uses: ./.github/workflows/workflow.yml

.prettierrc

@@ -0,0 +1,3 @@
+{
+  "singleQuote": false
+}

flake.lock

@@ -0,0 +1,40 @@
+{
+  "nodes": {
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1744868846,
+        "narHash": "sha256-5RJTdUHDmj12Qsv7XOhuospjAjATNiTMElplWnJE9Hs=",
+        "rev": "ebe4301cbd8f81c4f8d3244b3632338bbeb6d49c",
+        "revCount": 785333,
+        "type": "tarball",
+        "url": "https://api.flakehub.com/f/pinned/DeterminateSystems/nixpkgs-weekly/0.1.785333%2Brev-ebe4301cbd8f81c4f8d3244b3632338bbeb6d49c/01965c00-a987-7897-9240-abc0268d7590/source.tar.gz"
+      },
+      "original": {
+        "type": "tarball",
+        "url": "https://flakehub.com/f/DeterminateSystems/nixpkgs-weekly/%2A"
+      }
+    },
+    "nixpkgs-old": {
+      "locked": {
+        "lastModified": 1745279238,
+        "narHash": "sha256-AQ7M9wTa/Pa/kK5pcGTgX/DGqMHyzsyINfN7ktsI7Fo=",
+        "rev": "9684b53175fc6c09581e94cc85f05ab77464c7e3",
+        "revCount": 717196,
+        "type": "tarball",
+        "url": "https://api.flakehub.com/f/pinned/NixOS/nixpkgs/0.2411.717196%2Brev-9684b53175fc6c09581e94cc85f05ab77464c7e3/019660c5-eae1-7a61-9902-4417eac98039/source.tar.gz"
+      },
+      "original": {
+        "type": "tarball",
+        "url": "https://flakehub.com/f/NixOS/nixpkgs/0.2411.717196"
+      }
+    },
+    "root": {
+      "inputs": {
+        "nixpkgs": "nixpkgs",
+        "nixpkgs-old": "nixpkgs-old"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

@@ -0,0 +1,44 @@
+{
+  inputs = {
+    nixpkgs.url = "https://flakehub.com/f/DeterminateSystems/nixpkgs-weekly/*";
+
+    # For action-validator, which is broken with new rust versions
+    nixpkgs-old.url = "https://flakehub.com/f/NixOS/nixpkgs/0.2411.717196";
+  };
+
+  outputs =
+    { nixpkgs, nixpkgs-old, ... }:
+    let
+      inherit (nixpkgs) lib;
+
+      systems = [
+        "aarch64-linux"
+        "aarch64-darwin"
+        "x86_64-linux"
+        "x86_64-darwin"
+      ];
+
+      forEachSystem =
+        f:
+        lib.genAttrs systems (
+          system:
+          let
+            pkgs = nixpkgs.legacyPackages.${system};
+            pkgs-old = nixpkgs-old.legacyPackages.${system};
+          in
+          f { inherit pkgs pkgs-old; }
+        );
+    in
+    {
+
+      devShells = forEachSystem ({ pkgs, pkgs-old }: {
+        default = pkgs.mkShellNoCC {
+          buildInputs = [
+            pkgs.nodePackages.prettier
+
+            pkgs-old.action-validator
+          ];
+        };
+      });
+    };
+}