v0, Vercel's AI-powered app builder, just shipped a feature that tackles one of the most friction-heavy parts of iterating on a UI: communicating multiple, spatially-specific feedback points to the agent in one shot. The new annotations feature lets you click directly on elements in your live preview, attach comments to each one, and then fire them all off to the agent as a single consolidated prompt.

The problem it's solving

Anyone who has used v0 for more than a few sessions knows the pain: you finish a generation, scan the preview, and spot five things you want changed. A button is the wrong color. A heading is misaligned. A card needs more padding. A label is unclear. Right now, you either describe all of this in one long, tangled prompt, or you send five separate messages and watch the agent re-render the whole app five times, burning credits each time.