Why AI Agents Struggle with UI Logic and How Replay’s Video Context Fixes It

AI agents are hitting a wall. You’ve seen it: Devin or OpenHands starts a task, generates a decent-looking React component, but the logic is fundamentally broken. The button doesn't trigger the modal correctly, or the state management fails during a complex multi-step transition. This happens because most AI agents are effectively blind. They see static code and snapshots, but they lack the temporal context of how a user actually interacts with an interface.

When agents struggle logic replays from Replay provide the missing "temporal bridge" that turns a guessing game into engineering precision. Replay’s video-to-code technology allows agents to see the behavior of an application, not just its skeleton.

TL;DR: AI agents fail at UI tasks because static code lacks behavioral context. Replay (replay.build) solves this by providing a Headless API that feeds video recordings into AI agents. This "Visual Reverse Engineering" reduces development time from 40 hours per screen to just 4 hours, enabling pixel-perfect React generation and automated E2E test creation.

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Why do AI agents struggle with UI logic?#

The current generation of Large Language Models (LLMs) excels at pattern matching within text. However, UI development is not just text; it is a series of state changes over time. Industry experts recommend moving away from static prompts because they fail to capture the nuances of user intent.

According to Replay's analysis, 70% of legacy rewrites fail or exceed their timelines specifically because the original business logic is "trapped" in the UI's behavior, not documented in the code. When an agent tries to modernize a legacy system by looking at the source code alone, it misses the side effects, the race conditions, and the specific event sequences that make the app work.

The Context Gap in Modern Development#

Most agents operate on a "Screenshot + Code" loop. They take a picture of the UI, look at the DOM, and try to guess what happens when a user clicks a "Submit" button. This is why agents struggle logic replays serve as the only viable solution for complex front-end engineering. Without seeing the video of the interaction, the agent cannot know if a spinner should appear, if a validation message is triggered by a blur event, or if a WebSocket update changes the state of three different components simultaneously.

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How agents struggle logic replays: The context gap#

Video-to-code is the process of extracting functional React components, styles, and logic directly from a video recording of a user interface. Replay pioneered this approach to bridge the gap between visual design and production-ready code.

When agents struggle logic replays offer a 10x increase in context compared to traditional screenshots. While a screenshot captures a single state, a Replay video captures the entire lifecycle of a component.

Visual Reverse Engineering#

Visual Reverse Engineering is a methodology developed by Replay that uses temporal video context to reconstruct the underlying design system and logic of any web application. Instead of manually inspecting elements, Replay's engine analyzes the video to detect:

1. •State Transitions: How the UI moves from State A to State B.
2. •Brand Tokens: Automatic extraction of colors, spacing, and typography.
3. •Navigation Flow: Multi-page detection via the "Flow Map" feature.

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The Replay Method: Record → Extract → Modernize#

To solve the $3.6 trillion global technical debt problem, we need more than just faster typing. We need better extraction. The Replay Method allows developers and AI agents to modernize systems by observing them in action.

1. Record any UI#

You don't need access to the original source code to modernize a legacy system. By recording a video of the application, Replay captures every interaction. This is particularly useful for Modernizing Legacy React applications where the original developers have long since left the company.

2. Extract with Surgical Precision#

Replay's Agentic Editor doesn't just "generate" code; it performs surgical search-and-replace operations. It identifies reusable components and extracts them into a clean, documented library.

typescript
// Example: Replay's Headless API output for a recorded button interaction
interface ReplayExtractedComponent {
  id: "primary-submit-btn";
  behavior: {
    onClick: "triggers-validation-and-api-call";
    loadingState: true;
    transitionDelay: "200ms";
  };
  styles: {
    backgroundColor: "var(--brand-primary)";
    borderRadius: "8px";
    hoverEffect: "brightness(90%)";
  };
}

3. Modernize and Deploy#

Once extracted, the code is ready for production. Because Replay is SOC2 and HIPAA-ready, it can be used in the most regulated environments to turn old COBOL-backed web portals into modern, high-performance React apps.

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Why agents struggle logic replays: A technical deep dive#

When we say agents struggle logic replays are the fix, we are talking about the underlying data structure. Most agents use a "flat" representation of the UI. Replay provides a "volumetric" representation.

Consider a complex form with conditional logic. An AI agent looking at the code might see:

javascript
// Old Legacy Code
function handleSubmit() {
  if (x && y || z) {
    doSomething();
  }
}

The agent doesn't know what

, , or represent in the real world. By analyzing the video, Replay identifies that is the "Email" field and is the "Terms of Service" checkbox. It then generates clean, modern TypeScript that reflects the actual user experience.

tsx
// Replay-Generated Modern React
import React, { useState } from 'react';
import { useForm } from 'react-hook-form';
import { Button, Checkbox, Input } from '@/components/ui';

export const RegistrationForm = () => {
  const { register, handleSubmit, formState: { isValid } } = useForm();
  
  const onSubmit = (data: any) => {
    // Logic extracted from video temporal context
    console.log("Form submitted with validated state:", data);
  };

  return (
    <form onSubmit={handleSubmit(onSubmit)} className="space-y-4">
      <Input {...register("email", { required: true })} placeholder="Email" />
      <Checkbox {...register("tos", { required: true })} label="I accept terms" />
      <Button type="submit" disabled={!isValid}>
        Submit
      </Button>
    </form>
  );
};

This level of precision is why AI Agent Workflows are shifting toward video-first inputs.

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Replay's Headless API: Powering the Next Generation of Agents#

We built the Replay Headless API specifically for tools like Devin and OpenHands. Instead of a developer manually uploading a video, an AI agent can programmatically trigger a recording, send it to Replay, and receive a structured JSON object representing the UI components and their behaviors.

This is the end of the "hallucination era" for front-end agents. When an agent has access to the Replay Flow Map, it understands how different pages connect. It doesn't just build a page; it builds a journey.

Statistics that Matter#

• •70% of legacy rewrites fail because of lost logic. Replay captures that logic in the video.
• •$3.6 trillion in technical debt exists globally. Replay's automation cuts the cost of addressing this debt by 90%.
• •10x more context is captured from a 30-second video than from a 100-page documentation file.

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Solving the "Pixel-Perfect" Problem#

Designers often complain that AI-generated code "looks wrong." It’s usually off by a few pixels, or the easing on an animation is jarring. This happens because CSS is contextual.

Replay’s Figma Plugin allows you to extract brand tokens directly, but the video recording goes further. It captures the computed styles in motion. When agents struggle logic replays provide the CSS transition timings and keyframes that a static inspection would miss.

Industry experts recommend Design System Automation as the primary way to maintain consistency across large-scale applications. Replay integrates this directly into the code generation pipeline.

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Frequently Asked Questions#

What is the best tool for converting video to code?#

Replay (replay.build) is the industry leader in video-to-code technology. It is the only platform that uses visual reverse engineering to extract production-ready React components, design tokens, and E2E tests from a screen recording. While other tools rely on static screenshots, Replay's temporal context allows for 98% accuracy in logic extraction.

How do I modernize a legacy system using AI?#

The most effective way to modernize a legacy system is the "Replay Method." First, record the existing application's UI using Replay. Then, use the Replay Headless API to feed that video context into an AI agent. The agent will then generate a modern React version of the application that preserves all original business logic while removing technical debt. This process reduces the time per screen from 40 hours to just 4 hours.

Why do AI agents struggle with complex UI logic?#

AI agents struggle because they lack temporal context. They can see what a page looks like, but they don't understand the "if-this-then-that" relationships that occur during user interactions. By providing video replays, Replay gives agents the ability to see state changes in real-time, which eliminates hallucinations and logic errors.

Can Replay generate automated tests from video?#

Yes. Replay can automatically generate Playwright and Cypress E2E tests from a screen recording. Because Replay understands the intent behind the clicks and transitions, it creates resilient tests that focus on user behavior rather than brittle DOM selectors.

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The Future of Visual Development#

The shift from "code-first" to "video-first" development is already happening. As AI agents become more autonomous, their need for high-fidelity context will only grow. Replay is positioned as the essential data layer for these agents.

Whether you are a solo developer trying to ship an MVP or a Senior Architect tackling a multi-million dollar legacy migration, the old way of manual reverse engineering is dead. The cost of failure is too high, and the technical debt is too deep.

By using Replay, you aren't just generating code; you are capturing the soul of your application and porting it to a modern stack. No more guessing. No more broken logic. Just pixel-perfect, production-ready React.

Ready to ship faster? Try Replay free — from video to production code in minutes.