How do I auto-format code on save using conform.nvim?

Explanation

conform.nvim is a lightweight formatter plugin for Neovim that runs external formatters (prettier, black, gofmt, etc.) with proper error handling and fallback chains. It integrates seamlessly with format-on-save workflows.

How it works

• require('conform').format() — format the current buffer
• Formatters are configured per filetype
• Multiple formatters can be chained (run sequentially)
• Fallback formatters run only if primary ones aren't available

Example

require('conform').setup({
  formatters_by_ft = {
    python = { 'black' },
    javascript = { 'prettier' },
    go = { 'gofmt', 'goimports' },
    lua = { 'stylua' },
  },
  format_on_save = {
    timeout_ms = 500,
    lsp_fallback = true,
  },
})

Workflow:
1. Edit Python file
2. Save with :w
3. black runs automatically
4. Buffer is reformatted in-place

Tips

• lsp_fallback = true uses LSP formatting when no formatter is configured
• Use format_after_save for async formatting that doesn't block the UI
• :ConformInfo shows which formatters are available for the current buffer
• stop_after_first = true runs only the first available formatter in the list