diffedit.nvim

Edit .diff / patch files as real documents. Instead of deleting and re-typing lines, you edit + / - prefixed lines directly; diffedit keeps the @@ hunk counts in sync, flags broken structure, and highlights the reconstructed code with treesitter.

https://github.com/djakidjo/diffedit.nvim

The gap this fills: git's own git add -p has an editor mode, but there is no standalone, validated .diff editor. Existing plugins either only recompute @@ inside a git add -p temp buffer (rehunk.nvim), only apply patches to lazy.nvim packages (patchr.nvim, lazy-patcher.nvim), or only visualize diffs (patchview.nvim, jj-diff-stage.nvim).

Features

• Auto-recalculated hunk headers — @@ -12,5 +12,6 @@ tail is recomputed from the actual body lines on write (and via :DiffRecalc). Idempotent.
• o / O on +/- lines — inserts a new line with the same prefix and indent, so adding a line means o + type, not O + + + delete. Outside +/- lines the default behavior is preserved.
• Validation via vim.diagnostic:
  • ERROR — body line outside of any hunk header (broken structure),
  • WARN — hunk old/new counts differ from the actual body.
• Treesitter highlighting — the target file is reconstructed from and + lines, parsed in a scratch buffer, and the captures are copied back as extmarks (e.g. @keyword.lua, @number.lua).
• :DiffApply — git apply --recount on the current buffer (tolerant of stale hunk numbers). Runs in the git worktree root.
• :DiffShow — opens the target file side-by-side (or git show HEAD:path when it is not on disk).

Requirements

• Neovim 0.11+
• treesitter parsers for the languages you edit diffs of (optional, for highlighting)

Installation

With lazy.nvim:

{
  "djakidjo/diffedit.nvim",
  ft = "diff",
  config = function()
    require("diffedit").setup()
  end,
}

Usage

Open a .diff file. It is picked up automatically (FileType diff):

• o on a + line — new added line below with the same indent
• O on a - line — new removed line above with the same indent
• :w — recalculates @@ counts, re-validates, re-highlights

Commands:

Command	Effect
:DiffRecalc	Recompute @@ counts from the body lines
:DiffCheck	Run validation and report via vim.diagnostic
:DiffApply	git apply --recount the current buffer
:DiffShow	Open the target file in a vsplit

Options

require("diffedit").setup({
  -- Enable treesitter-based code highlighting
  hl_code = true,
  -- Build the highlight group from a capture + language
  hl_group = function(capture, lang)
    return "@" .. capture .. "." .. lang
  end,
})

Limitations

• Highlighting works for single-file diffs only (exactly one +++ line).
• Applying to the worktree requires the diff to be in a git repository.

Similar plugins

• jetm/rehunk.nvim — hunk count fixups, only in the git add -p editor buffer
• nhu/patchr.nvim, one-d-wide/lazy-patcher.nvim — patches for lazy.nvim
• sminrana/nvim-filediff, moha-abdi/patchview.nvim — diff viewing only