return {
  { "rcarriga/nvim-notify" },

  -- resize the window
  {
    "mrjones2014/smart-splits.nvim",
    version = "v1.2.2",
    config = function()
      require "plugins/smart-split/config"()
    end,
  },

  -- buffer delete
  { "famiu/bufdelete.nvim" },

  -- session
  {
    "Shatur/neovim-session-manager",
    dependencies = { "nvim-lua/plenary.nvim" },
    config = function()
      local Path = require "plenary.path"
      local config = require "session_manager.config"
      require("session_manager").setup {
        sessions_dir = Path:new(vim.fn.stdpath "data", "sessions"), -- The directory where the session files will be saved.
        session_filename_to_dir = session_filename_to_dir, -- Function that replaces symbols into separators and colons to transform filename into a session directory.
        dir_to_session_filename = dir_to_session_filename, -- Function that replaces separators and colons into special symbols to transform session directory into a filename. Should use `vim.loop.cwd()` if the passed `dir` is `nil`.
        autoload_mode = config.AutoloadMode.Disabled, -- Define what to do when Neovim is started without arguments. Possible values: Disabled, CurrentDir, LastSession
        autosave_last_session = true, -- Automatically save last session on exit and on session switch.
        autosave_ignore_not_normal = true, -- Plugin will not save a session when no buffers are opened, or all of them aren't writable or listed.
        autosave_ignore_dirs = { "/", "~", "/tmp/" }, -- A list of directories where the session will not be autosaved.
        autosave_ignore_filetypes = { -- All buffers of these file types will be closed before the session is saved.
          "gitcommit",
          "gitrebase",
        },
        autosave_ignore_buftypes = {}, -- All buffers of these bufer types will be closed before the session is saved.
        autosave_only_in_session = false, -- Always autosaves session. If true, only autosaves after a session is active.
        max_path_length = 80, -- Shorten the display path if length exceeds this threshold. Use 0 if don't want to shorten the path at all.
      }

      -- automatic open neotree sidebar when a session opened
      local hardhacker_config_group = vim.api.nvim_create_augroup("HardHackerConfigGroup", {})
      vim.api.nvim_create_autocmd({ "User" }, {
        pattern = "SessionLoadPost",
        group = hardhacker_config_group,
        callback = function()
          vim.api.nvim_command "Neotree position=left source=filesystem action=show"
        end,
      })
    end,
  },
  -- zen-mode
  {
    "folke/zen-mode.nvim",
    opts = {
      window = {
        backdrop = 1, -- shade the backdrop of the Zen window. Set to 1 to keep the same as Normal
        -- height and width can be:
        -- * an absolute number of cells when > 1
        -- * a percentage of the width / height of the editor when <= 1
        -- * a function that returns the width or the height
        width = 120, -- width of the Zen window
        height = 0.9, -- height of the Zen window
        -- by default, no options are changed for the Zen window
        -- uncomment any of the options below, or add other vim.wo options you want to apply
        options = {
          signcolumn = "no", -- disable signcolumn
          number = false, -- disable number column
          relativenumber = false, -- disable relative numbers
          cursorline = false, -- disable cursorline
          cursorcolumn = false, -- disable cursor column
          foldcolumn = "0", -- disable fold column
          list = false, -- disable whitespace characters
        },
      },
      -- callback where you can add custom code when the Zen window opens
      on_open = function(win) end,
      -- callback where you can add custom code when the Zen window closes
      on_close = function() end,
    },
  },
  {
    "folke/twilight.nvim",
    opts = {
      dimming = {
        alpha = 0.25, -- amount of dimming
        -- we try to get the foreground from the highlight groups or fallback color
        -- color = { "Normal", "#eee9fc" },
        -- term_bg = "#000000", -- if guibg=NONE, this will be used to calculate text color
        inactive = false, -- when true, other windows will be fully dimmed (unless they contain the same buffer)
      },
      context = 10, -- amount of lines we will try to show around the current line
      treesitter = true, -- use treesitter when available for the filetype
      -- treesitter is used to automatically expand the visible text,
      -- but you can further control the types of nodes that should always be fully expanded
      expand = { -- for treesitter, we we always try to expand to the top-most ancestor with these types
        "function",
        "method",
        "table",
        "if_statement",
      },
      exclude = {}, -- exclude these filetypes
    },
  },
}