Seeing what actually changed (diff)

Before you save a change — and especially before you accept a change an AI made — you want to see exactly what's different. That's a diff. It shows you, line by line, what was added (usually in green) and what was removed (usually in red).

This is one of your most important habits. The whole philosophy of vibe coding is understand what you ship. You don't have to type the code, but you do have to look at what changed and roughly understand it. The diff is where you do that.

# See what you've changed but not yet committed
git diff

# See what's staged and ready to be committed
git diff --staged

When the AI says "done, I updated the file," your next move is to look at the diff. If you see it deleted something you needed, you catch it now — not after it's shipped.