The problem
An agent can mock up a screen in seconds, and it is far easier to judge a screen than a description of one. Giving feedback on it is the slow part. You type into the chat: "the button under the second card, no, the other one, make it less loud". The agent guesses which element you meant, and often guesses wrong.
How it works with Onlay
Ask your agent to publish the mockup:
onlay push checkout-mockup.html
You get a link. Open it and:
- Pin a comment on anything: a button, a card, an icon, a number in a chart. The pin stays on that element.
- Select text and comment on the wording of a label or a heading.
- Fix a label yourself, if editing is on: click it and type.
- Draw a circle or an arrow on the page, or paste a screenshot into a comment.
Then tell your agent "pull the feedback and fix it". It runs onlay pull checkout-mockup.html and gets each comment with the element it is pinned to (the block's data-onlay-id, its place in the page and the lines of the file it came from), plus your words. It changes the file and pushes version 2 to the same link, with a reply on each thread saying what it did.
Sharing it with others
Send the same link to a designer, a product manager or a client. Anyone with the link can comment without an account; they type a name and an email once. Their comments come back on the same pull, each with their name, so your agent sees who asked for what.
Interactive prototypes
A mockup can be a working prototype: tabs that switch, a form that validates, a slider that changes a chart. Readers can comment on whatever state they put the page in. On the Free plan a page cannot call other servers, so a prototype uses data baked into the file; Pro lifts that.
When something else fits better
If the design lives in Figma and your team reviews there, keep commenting in Figma. Onlay is for what your agent produces as HTML. For a web app that is already deployed, see comments on a website or web app.