Git said everything merged fine. My code was gone.

Merged a feature branch yesterday. Git said zero conflicts. Pushed to main. My entire authentication module disappeared. Three hours of code just vanished. Spent an hour thinking Git was broken. It wasn't. I was using merge wrong. What happened Working on two branches: feature/auth adding OAuth login feature/ui updating frontend Both touched app.py but different sections. Merged feature/auth first, worked fine. Then merged feature/ui. git checkout main git merge feature/ui # "Auto-merging app.py