Nvim: Persistent colorscheme choice

In general we arecused to set our colorscheme in a options file where we write our choice, but nativelly there is not a dinamic system to allow us change our colirscheme.

Just some steps

First create a theme.json in your nvim folder

~/.config/nvim/theme.json where we will save the color. In my case the file looks like:

{"colorscheme":"onedark"}

in your init.lua require a file require('core.theme') with this content:

-- ~/.config/nvim/lua/core/theme.lua

local theme_file = vim.fn.stdpath('config') .. '/theme.json'
local colorscheme = 'habamax' -- fallback

-- Tenta ler o arquivo theme.json
local function load_colorscheme()
  local ok, json = pcall(vim.fn.readfile, theme_file)
  if ok and json and #json > 0 then
    local decoded = vim.fn.json_decode(table.concat(json, '\n'))
    if decoded and decoded.colorscheme then
      return decoded.colorscheme
    end
  end
  return colorscheme
end

vim.defer_fn(function()
  local cs = load_colorscheme()
  local ok = pcall(vim.cmd.colorscheme, cs)
  if not ok then
    vim.notify('Colorscheme ' .. cs .. ' not found! Using fallback.', vim.log.levels.WARN)
    pcall(vim.cmd.colorscheme, colorscheme)
  end
end, 10)

Now an autocommand to detect when you choose a new theme:

vim.api.nvim_create_autocmd('ColorScheme', {
  group = vim.api.nvim_create_augroup('SaveColorscheme', { clear = true }),
  callback = function(args)
    local theme = args.match
    if theme == 'habamax' then return end -- evita salvar fallback
    local path = vim.fn.stdpath('config') .. '/theme.json'
    local ok, f = pcall(io.open, path, 'w')
    if ok and f then
      f:write(vim.json.encode({ colorscheme = theme }))
      f:close()
    end
  end,
})

You can setup your telescope pickers.colorscheme with:

Note: Once we have an outcommand you can ignore the code below but if you want to learn how do it via telescope...

colorscheme = {
          enable_preview = true,
          previewer = false,
          layout_config = {
            height = 0.4,
            width = 0.5,
          },
          attach_mappings = function(_, map)
            local actions = require('telescope.actions')
            local action_state = require('telescope.actions.state')

            map('i', '<CR>', function(prompt_bufnr)
              local selection = action_state.get_selected_entry()
              local theme = selection.value
              actions.close(prompt_bufnr)
              vim.cmd.colorscheme(theme)

              -- salva o tema no theme.json
              local path = vim.fn.stdpath('config') .. '/theme.json'
              local ok, file = pcall(io.open, path, 'w')
              if ok and file then
                file:write(vim.fn.json_encode({ colorscheme = theme }))
                file:close()
                vim.notify('Tema salvo: ' .. theme, vim.log.levels.INFO)
              else
                vim.notify('Erro ao salvar o tema!', vim.log.levels.ERROR)
              end
            end)

            return true
          end,
        },

and let your choice be saved automatically