The "no, the other one" problem
App builders are brilliant at the first draft and weirdly bad at the second. The first prompt describes a whole page. Every prompt after that is about one specific thing on it, and words are terrible at naming one specific thing. "The button under the pricing cards" matches three buttons. The agent picks one. It is usually not yours.
Use the built-in picker when you are inside the preview
Both big app builders ship a way to click an element in their own preview and edit it: Lovable has visual edits and v0 has a design mode. If the thing you want changed is in their preview pane, use them. They are quick and they know exactly which component you clicked.
The catch: they only work inside their own preview. The moment the bug is somewhere else, you are back to describing it.
When the bug is not in the preview
Most real bugs are not. They are in:
- your deployed app, on the real domain, with real data;
- localhost, after you pulled the code into Cursor;
- a browser the preview does not match, or a state it cannot reach (logged in, mid-checkout, an error toast).
Here the trick is the same one that works on a teammate: a tight crop of the element plus one sentence. Crop with ⌘Ctrl⇧4 around just that element, paste it into the chat, and say what is wrong and what you want instead:
"This 'Order now' button blends into the hero. Give it the brand fill and white text so it reads as the main action."
A crop of one button cannot be confused with the other two. The agent stops guessing.
When there are five things to fix
Real feedback comes in batches: the spacing here, the colour there, this error overlapping that field. Doing crop, paste, type five times is where the flow dies. So do it in one go: point at each thing while you talk, number them, and send one brief with [1] to [5] matched to five crops.
That is exactly what Deiko does. Double-tap Right Option, point at the first thing and talk, point at the next, hold Left Option to circle a whole region, and tap Right Option to stop. You get one numbered brief with every crop attached, and it pastes the same way into v0, Lovable, Replit, Cursor, Claude Code or ChatGPT. Same gesture, whichever builder you are in this week.
Questions people ask
How do I edit a specific element in Lovable?
Inside Lovable's preview, use its visual edits to click the element. Outside the preview, paste a tight crop of the element with one sentence about the change.
How do I make v0 change one component instead of the whole page?
Point at the component: use v0's design mode in its preview, or paste a crop of just that component and describe the change in one sentence.
How do I show Cursor which button I mean?
Paste a cropped screenshot of just that button into the Agent chat with what it does now and what it should do.
Can I send several UI fixes to an AI builder at once?
Yes. Number them, attach one crop per item, and reference them as [1], [2], [3] in one message. Deiko builds that numbered brief for you from a single point-and-talk session.