rehunk.nvim

Automatic diff header recalculation for git add -p hunk editing.

When you edit a hunk during interactive staging (git add -p → e), git requires the @@ -X,Y +A,B @@ header to match the actual line counts. Manual counting is error-prone and leads to "Your edited hunk does not apply" errors. This plugin automatically recalculates the header on save.

Installation

lazy.nvim

{
  "jetm/rehunk.nvim",
  ft = "diff",  -- Load when opening diff files
}

packer.nvim

use {
  "jetm/rehunk.nvim",
  ft = "diff",
}

Usage

1. Run git add -p and select a hunk
2. Press e to edit the hunk
3. Make your changes (add/remove lines)
4. Save the file - the header is automatically recalculated
5. Close the editor - git applies the corrected hunk

Manual Recalculation

The :RehunkRecalculate command is available in hunk edit buffers if you need to recalculate without saving.

Configuration

The plugin works out of the box with zero configuration. Optional settings:

{
  "jetm/rehunk.nvim",
  ft = "diff",
  opts = {
    auto_recalculate = true,  -- Recalculate on save (default: true)
  },
}

Requirements

• Neovim 0.8+
• No external dependencies

How It Works

The plugin detects when Neovim opens git's hunk edit temp file (*addp-hunk-edit.diff). It parses the diff, counts lines by prefix (+ additions, - deletions, context), and updates the header counts:

• Y (original count) = context lines + deletion lines
• B (new count) = context lines + addition lines

Local Development

Setup

Clone the repository and add it to your Neovim config:

-- lazy.nvim local development
{
  dir = "~/path/to/rehunk.nvim",
  ft = "diff",
}

Testing

Run tests with:

nvim --headless -u tests/minimal_init.lua -c "PlenaryBustedDirectory tests/ {minimal_init = 'tests/minimal_init.lua'}"

Or test core functions in isolation (no Neovim needed):

lua tests/core_spec.lua

Manual Testing

# Create a test file with changes
echo -e "foo\nbar\nbaz" > /tmp/test.txt
git init /tmp/test-repo && cd /tmp/test-repo
echo -e "foo\nbar\nbaz" > test.txt && git add test.txt && git commit -m "init"
echo -e "1\n2\n3" > test.txt

# Test interactive staging
git add -p
# Select 'e' to edit, modify the hunk, save

License

MIT