Long Horizon
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UI Feedback

UI Feedback lets you annotate your application's interface with comments that AI agents can understand and act on. Instead of describing UI changes in text, point directly at elements and explain what needs to change.

How it works

  1. Open your application in Long Horizon and enter feedback mode
  2. Click anywhere on the screen to place a comment
  3. Add as many comments as needed across different UI elements
  4. Click Done to save your feedback session
  5. Copy the generated prompt and share it with your AI coding agent

When your agent retrieves the feedback, it receives the screenshot with your annotations, the HTML context of each element you commented on, and your feedback text—everything needed to implement the changes.

Starting a feedback session

There are several ways to start giving feedback:

  • From the sidebar: Click the UI Feedback section and select "Open application and give feedback"
  • From the toolbar: While in Step Mode or Take Me Here mode, click the feedback button in the toolbar

Adding comments

Click anywhere on the screen to place a comment. You can:

  • Click on different areas to add multiple comments
  • Click on an existing comment to edit it
  • Place multiple comments on the same element if needed

Completing a session

When you click Done in the feedback toolbar:

  1. Long Horizon captures a full-page screenshot with all your comments visible
  2. For each comment, it identifies the UI element at that location and captures its HTML
  3. Everything is saved locally with a unique reference ID
  4. In the Feedback screen of Long Horizon, you can see the feedback session and copy the prompt to share with your AI agent

The generated prompt includes the reference ID and instructions for the agent to retrieve your feedback using the retrieve_ui_feedback MCP tool.

What agents receive

When an AI agent calls the retrieve_ui_feedback tool with your feedback ID, it receives:

  • Screenshot: A JPEG image showing your application with all comment annotations visible
  • Element HTML: The sanitized HTML of each element you commented on, including the element and its first-level children
  • Comments: Your feedback text paired with the corresponding elements

This gives the agent visual context, structural context, and your specific instructions—everything needed to understand and implement your requested changes.

Tips for effective feedback

  • Be specific: Instead of "make this look better," say "add a 1px border and subtle shadow"
  • Group related changes: If multiple elements need the same treatment, mention it in one comment
  • Reference design systems: If you have a design system, reference token names or component variants
  • Include context: Explain why a change is needed, not just what to change
  • One screen at a time: Focus each feedback session on a single view or flow for clarity