Patch Creation Way

Source: hooks/ways/softwaredev/delivery/patches/patches.md

Frontmatter

Field	Value
description	creating and applying patch files, git diff generation, patch series management
vocabulary	patch diff apply hunk unified series format-patch
pattern	.patch\b|git.?(apply|am)|patch.?(set|series)
commands	git\ apply|git\ diff.*\>
files	.(patch|diff)$
refire	0.15
scope	agent, subagent

Golden Rule: Never hand-write patch content. Always generate patches from real file changes using git diff.

Single Patch

# 1. Make the actual edit to the file
# 2. Generate the patch
git diff path/to/file > change.patch
# 3. Revert if you only needed the patch
git checkout path/to/file

Modifying an Existing Patch

# 1. Apply the patch first
git apply existing.patch
# 2. Make your modifications to the file
# 3. Regenerate the patch
git diff path/to/file > existing.patch
# 4. Revert
git checkout path/to/file

Patch Series

Patches in a series are cumulative - each assumes prior patches are applied.

# To modify patch N in a series (e.g., 0003-foo.patch):
git apply 0001-*.patch 0002-*.patch  # Apply predecessors
git apply 0003-*.patch               # Apply target patch
# Make your changes
git diff > 0003-foo.patch            # Regenerate
# Verify downstream patches still apply:
git apply --check 0004-*.patch       # Check only, don't apply

If downstream patches fail after your change: - You've changed context they depend on - Regenerate them too (apply each, capture, repeat)

Key Commands

Task	Command
Generate patch	git diff [file] > name.patch
Apply patch	git apply name.patch
Check if applies	git apply --check name.patch
Revert file	git checkout path/to/file
Compare two files	git diff --no-index old new