feat: restructure dev-components/dev-registry with direnv

features/dev.nix

@@ -9,7 +9,6 @@
         pkgs.git
         packages.git-linearize
         packages.ggman
-        pkgs.go
         pkgs.python3
         pkgs.mdbook
         pkgs.marksman
@@ -22,9 +21,5 @@
         pkgs.osc
       ];
 
-      programs.direnv = {
-        enable = true;
-        nix-direnv.enable = true;
-      };
     };
 }

features/direnv/default.nix

@@ -13,4 +13,14 @@
         };
       };
     };
+
+  home = _: {
+    programs.direnv = {
+      enable = true;
+      nix-direnv.enable = true;
+      config.global.hide_env_diff = true;
+    };
+
+    xdg.configFile."direnv/lib/use_dev.sh".source = ./use_dev.sh;
+  };
 }

features/direnv/use_dev.sh

@@ -0,0 +1,80 @@
+# shellcheck shell=bash
+# composable nix devshell from matej.nix
+# usage in .envrc: use dev uv_14 pg_18
+
+# generates a flake and delegates to use_flake at the calling scope
+use_dev() {
+	local nix_list=""
+	for c in "$@"; do
+		if [[ ! "$c" =~ ^[a-zA-Z_][a-zA-Z0-9_]*$ ]]; then
+			log_error "use_dev: invalid component name: $c"
+			return 1
+		fi
+		nix_list="$nix_list \"$c\""
+	done
+
+	local system
+	case "$(uname -s)-$(uname -m)" in
+	Linux-x86_64) system="x86_64-linux" ;;
+	Linux-aarch64) system="aarch64-linux" ;;
+	Darwin-x86_64) system="x86_64-darwin" ;;
+	Darwin-arm64) system="aarch64-darwin" ;;
+	esac
+
+	if [[ -z "$system" ]]; then
+		log_error "use_dev: unsupported platform: $(uname -s)-$(uname -m)"
+		return 1
+	fi
+
+	local dev_path nixpkgs_path registry_filter
+	# shellcheck disable=SC2016 # $id is a jq variable, not shell
+	registry_filter='.flakes[] | select(.from.id == $id) | .to.path'
+
+	local registry_file="${XDG_CONFIG_HOME:-$HOME/.config}/nix/registry.json"
+	if [[ ! -f "$registry_file" ]]; then
+		registry_file="/etc/nix/registry.json"
+	fi
+
+	dev_path="$(jq -re --arg id dev "$registry_filter" "$registry_file" 2>/dev/null)"
+	nixpkgs_path="$(jq -re --arg id nixpkgs "$registry_filter" "$registry_file" 2>/dev/null)"
+
+	if [[ -z "$dev_path" ]]; then
+		log_error "use_dev: 'dev' not found in nix registry"
+		return 1
+	fi
+	if [[ -z "$nixpkgs_path" ]]; then
+		log_error "use_dev: 'nixpkgs' not found in nix registry"
+		return 1
+	fi
+
+	local components_hash project_hash cache_dir
+	components_hash="$(sha256sum "$dev_path/flake/dev-components.nix" 2>/dev/null | cut -c1-16)"
+	project_hash="$(echo "$PWD" | sha256sum | cut -c1-16)"
+	cache_dir="${XDG_CACHE_HOME:-$HOME/.cache}/dev-flakes/$project_hash"
+	mkdir -p "$cache_dir"
+
+	cat >"$cache_dir/flake.nix.tmp" <<DEVFLAKE
+# dev-components: $components_hash
+{
+  inputs.dev = { url = "path:${dev_path}"; flake = false; };
+  inputs.nixpkgs.url = "path:${nixpkgs_path}";
+  outputs = { dev, nixpkgs, ... }:
+    let
+      system = "${system}";
+      pkgs = nixpkgs.legacyPackages.\${system};
+      devLib = import "\${dev}/flake/dev-components.nix" { inherit pkgs; lib = nixpkgs.lib; };
+    in {
+      devShells.\${system}.default = devLib.mkComponentShell [$nix_list ];
+    };
+}
+DEVFLAKE
+
+	if ! cmp -s "$cache_dir/flake.nix.tmp" "$cache_dir/flake.nix" 2>/dev/null; then
+		mv "$cache_dir/flake.nix.tmp" "$cache_dir/flake.nix"
+		rm -f "$cache_dir/flake.lock"
+	else
+		rm "$cache_dir/flake.nix.tmp"
+	fi
+
+	use_flake "path:$cache_dir"
+}