new flake command helper

flakes/common/nix_modules/essentials/default.nix

@@ -64,5 +64,6 @@ with lib;
     (builtins.readFile ./unix_utils.func.sh)
     (builtins.readFile ./nixpkg.func.sh)
     (builtins.readFile ./envrc-import.func.sh)
+    (builtins.readFile ./flake.func.sh)
   ];
 }

flakes/common/nix_modules/essentials/flake.func.sh

@@ -0,0 +1,133 @@
+_flake_usage() {
+  cat <<'EOF'
+usage:
+  flake update                 pick inputs via fzf
+  flake update <name...>       update specific inputs
+  flake update -a|--all        update all inputs
+EOF
+}
+
+_flake_root() {
+  local dir
+  dir="$(pwd -P)"
+
+  while [ "$dir" != "/" ]; do
+    if [ -f "$dir/flake.nix" ]; then
+      echo "$dir"
+      return 0
+    fi
+    dir="$(dirname "$dir")"
+  done
+
+  return 1
+}
+
+flake() {
+  local subcommand
+  subcommand="${1:-}"
+
+  case "$subcommand" in
+    update)
+      shift
+
+      local root
+      root="$(_flake_root)" || {
+        echo "Error: not in a flake directory (missing flake.nix)" >&2
+        return 1
+      }
+
+      local lock_file
+      lock_file="$root/flake.lock"
+
+      local all
+      all=0
+
+      while [ $# -gt 0 ]; do
+        case "$1" in
+          -a|--all)
+            all=1
+            shift
+            ;;
+          -h|--help)
+            _flake_usage
+            return 0
+            ;;
+          --)
+            shift
+            break
+            ;;
+          -*)
+            echo "Error: unknown flag: $1" >&2
+            _flake_usage >&2
+            return 1
+            ;;
+          *)
+            break
+            ;;
+        esac
+      done
+
+      if [ "$all" -eq 1 ]; then
+        (cd "$root" && nix flake update)
+        return $?
+      fi
+
+      if [ $# -gt 0 ]; then
+        echo "Updating inputs: $*"
+        (cd "$root" && nix flake update "$@")
+        return $?
+      fi
+
+      if [ ! -f "$lock_file" ]; then
+        echo "Error: missing $lock_file" >&2
+        echo "Run: (cd \"$root\" && nix flake lock)" >&2
+        return 1
+      fi
+
+      if ! command -v fzf >/dev/null 2>&1; then
+        echo "Error: fzf not found" >&2
+        return 1
+      fi
+
+      if ! command -v jq >/dev/null 2>&1; then
+        echo "Error: jq not found" >&2
+        return 1
+      fi
+
+      local selected
+      selected="$(
+        jq -r '.nodes.root.inputs | keys[]' "$lock_file" | \
+          fzf --multi \
+            --prompt='flake update > ' \
+            --header='TAB to select, ENTER to update'
+      )"
+
+      if [ -z "$selected" ]; then
+        echo "No inputs selected"
+        return 1
+      fi
+
+      local inputs
+      inputs=()
+
+      while IFS= read -r input; do
+        [ -z "$input" ] && continue
+        inputs+=("$input")
+      done <<< "$selected"
+
+      echo "Updating inputs: ${inputs[*]}"
+      (cd "$root" && nix flake update "${inputs[@]}")
+      return $?
+      ;;
+
+    -h|--help|help|"")
+      _flake_usage
+      ;;
+
+    *)
+      echo "Error: unknown subcommand: $subcommand" >&2
+      _flake_usage >&2
+      return 1
+      ;;
+  esac
+}