mergefix

AI-powered git merge conflict resolver — run one command, review the diff, apply.

$ mergefix

╭──────────────────────────────────────────────────────╮
│ mergefix  ·  3 files  ·  7 conflicts  ·  provider: claude │
╰──────────────────────────────────────────────────────╯

→ src/auth.py (2 conflicts)

  Conflict 1/2
  ours: main
  theirs: feature/oauth
  ✓ Resolution:
    def authenticate(user, password):
        return bcrypt.checkpw(password.encode(), user.password_hash)

  Conflict 2/2
  ours: main
  theirs: feature/oauth
  ✓ Resolution:
    SESSION_TIMEOUT = 3600  # keep shorter timeout from main

Diff:
--- a/src/auth.py
+++ b/src/auth.py
@@ -12,7 +12,4 @@ def get_user(user_id):
-<<<<<<< HEAD
-    return hashlib.md5(password.encode()).hexdigest()
-=======
-    return bcrypt.checkpw(password.encode(), user.password_hash)
->>>>>>> feature/oauth
+    return bcrypt.checkpw(password.encode(), user.password_hash)

  Apply resolutions to src/auth.py? [Y/n] y
  ✓ Applied

✅ All 3 file(s) resolved.
Run `git diff` to review changes, then `git add` to mark as resolved.

Install

pip install mergefix

Set your API key (or use Ollama for free local resolution):

export ANTHROPIC_API_KEY=your-key   # Claude (default, recommended)
export OPENAI_API_KEY=your-key      # or OpenAI
# or: mergefix --provider ollama    # local, no API key needed

Usage

# Resolve all conflicts in the current repo (most common)
mergefix

# Resolve a specific file
mergefix src/auth.py src/db.py

# Preview resolutions without writing (safe to run anytime)
mergefix --preview

# Auto-apply all resolutions without prompting (CI/scripting)
mergefix --yes

# Keep original files as .orig backups
mergefix --backup

# Give the AI extra context about your codebase
mergefix --context "Python web app, prefer async patterns, strict type hints"

# Use local Ollama (free, no API key)
mergefix --provider ollama

# Use OpenAI
mergefix --provider openai --model gpt-4o

How it works

1. Scans for files with <<<<<<< conflict markers (or use specific files)
2. Parses each conflict block (supports 2-way and 3-way / diff3 style)
3. Calls the AI with both sides of each conflict + surrounding context
4. Displays each resolution in syntax-highlighted code blocks
5. Shows a colorized unified diff of all changes
6. Asks for confirmation before writing (skip with --yes)
7. Writes the resolved content; optionally creates .orig backups

The AI sees the full file context, not just the conflict lines — so it understands the surrounding code and makes semantically correct resolutions.

Supports

• Languages: Any language (Python, JS, TypeScript, Go, Rust, Java, Ruby, etc.)
• Conflict styles: 2-way (default git) and 3-way / diff3
• Providers: Claude (default), OpenAI, Ollama (local, free)
• Multiple conflicts: Resolves all conflicts in a file in one AI call
• Multiple files: Processes all conflicted files in one run

Pre-merge hook

Add to your workflow to catch issues early:

# After a merge, resolve all conflicts and review:
git merge feature-branch
mergefix --preview  # preview only
mergefix            # apply
git add -A
git commit

Or as a one-liner for scripting:

git merge feature-branch && mergefix --yes && git add -A && git commit -m "resolve merge conflicts"

Part of the git toolkit

mergefix is part of a suite of AI-powered git tools:

Tool	What it does
gitbrief	Pack your git history into LLM context
gpr	Generate PR descriptions and commit messages
critiq	AI code reviewer before you push
standup-ai	Generate daily standups from git history
changelog-ai	Generate CHANGELOG from commits
mergefix	Resolve merge conflicts with AI

License

MIT