{
  description = "Go backend template — Go HTTP server, PostgreSQL, sessions, HTMX/Alpine.js frontend";

  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
    flake-utils.url = "github:numtide/flake-utils";
  };

  outputs =
    { self, nixpkgs, flake-utils }:
    flake-utils.lib.eachDefaultSystem (
      system:
      let
        pkgs = import nixpkgs { inherit system; };
        go = pkgs.go_1_24;
      in
      {
        packages.default = pkgs.buildGoModule {
          pname = "go-backend";
          version = "0.1.0";
          src = ./.;

          subPackages = [ "cmd" ];

          # `go.sum` only pins 3 modules today, but this hash still has to
          # match nix's vendor fetch. `nix build` will fail on a mismatch and
          # print the correct value to paste in here.
          vendorHash = "sha256-AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=";

          nativeBuildInputs = [ pkgs.makeWrapper ];

          # The server reads templates/static assets from a relative "./ui"
          # path (see internal/handlers/templates.go, cmd/main.go), so ship
          # that directory next to the binary and cd there before exec,
          # mirroring what the Dockerfile does.
          postInstall = ''
            mkdir -p $out/share/go-backend
            cp -r ${./ui} $out/share/go-backend/ui
            mv $out/bin/cmd $out/bin/go-backend
            wrapProgram $out/bin/go-backend --run "cd $out/share/go-backend"
          '';

          meta.mainProgram = "go-backend";
        };

        apps.default = flake-utils.lib.mkApp { drv = self.packages.${system}.default; };

        devShells.default = pkgs.mkShell {
          packages = [
            go
            pkgs.gopls
            pkgs.gotools
            pkgs.delve
            pkgs.goose
            pkgs.sqlc
            pkgs.air
            pkgs.postgresql_16
            pkgs.gnumake
          ];

          shellHook = ''
            echo "go-backend dev shell — $(go version)"
          '';
        };

        formatter = pkgs.nixpkgs-fmt;
      }
    );
}