A coworker took credit for my work. What do I do?

There are three moves and two of them are wrong.

Wrong move one: say nothing, seethe, promise yourself you will remember. That makes you a Spectator and it teaches the room that your team's work is up for grabs.

Wrong move two: call it out hot, in the meeting, in front of the director. Now you are the person who made it weird, and the credit fight buried the actual work.

The third move is quiet and precise. In the room, one calm sentence that reattaches the work without heat: "Glad this landed, this came out of the work my team has been running for weeks." Then handle the peer directly, afterward, in private. You protect your team's credit where it counts and you keep your composure where everyone is watching.

The tell of a strong leader here is not aggression. It is timing.