{
  nix-shell = {
    wraps = "nix-shell";
    body = ''
      command nix-shell $argv --command "fish"
    '';
  };
  nix = {
    wraps = "nix";
    body = ''
      if status is-interactive
        and test (count $argv) = 1 -a "$argv[1]" = develop
          nix develop --command (status fish-path)
      else
        command nix $argv
      end
    '';
  };
  nix-prefetch-hash = {
    body = ''
      nix-hash --type sha256 --to-base64 (nix-prefetch-url $argv)
    '';
  };
  fish_jj_prompt = {
    body = ''
      if not command -sq jj
          return 1
      end
      if not command -sq timeout
          return 1
      end
      if set -q FISH_JJ
          return 0
      end
      if not jj root &>/dev/null
          return 1
      end

      # Generate prompt
      set -l info "$(
          timeout 5 jj log --ignore-working-copy --no-graph --color=always --revisions=@ --template "
              separate(
                  ' ',
                  self.change_id().shortest(),
                  bookmarks.join(', '),
                  if(conflict, label('conflict', '×')),
                  if(empty, label('empty', '(empty)')),
                  if(divergent, label('divergent', '(divergent)')),
                  if(hidden, label('hidden', '(hidden)')),
              )
          "
      )"
      or return 1

      if test -n $info
          printf ' (jj: %s)' $info
      else
          return 1
      end
    '';
  };
  fish_vcs_prompt = {
    body = ''
      fish_jj_prompt $argv
      or fish_git_prompt $argv
      or fish_hg_prompt $argv
      or fish_fossil_prompt $argv
    '';
  };
}