Mastering Multipage Context Detection for Automated Site-Wide UI Updates

Most UI modernization projects fail because developers treat web pages like static posters rather than living, breathing state machines. When you capture a screenshot of a login page, you see a box and a button. You miss the redirect logic, the global error handling, and the shared navigation state that connects that page to the rest of the application. This "context blindness" is why 70% of legacy rewrites fail or exceed their original timelines.

To bridge this gap, engineering teams are now mastering multipage context detection. This isn't just about reading code; it's about understanding the temporal relationship between different screens. Replay (replay.build) has pioneered a method called Visual Reverse Engineering that uses video recordings to capture this exact context, turning a simple screen recording into a fully functional, interconnected React design system.

TL;DR: Traditional AI coding tools fail because they lack "contextual awareness" of how pages link together. Mastering multipage context detection allows Replay to map user flows, extract shared components, and generate production-ready React code from video recordings. By using Replay’s Flow Map and Headless API, teams reduce manual UI development from 40 hours per screen to just 4 hours, effectively tackling the $3.6 trillion global technical debt crisis.

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What is Multipage Context Detection?#

Multipage context detection is the ability of an AI system to identify and maintain state, design tokens, and navigational logic across multiple distinct URLs or application states.

In a standard manual rewrite, a developer looks at Page A and Page B separately. They might duplicate CSS or miss that the "Submit" button on Page A uses the same validation logic as the "Update" button on Page B. Replay solves this by analyzing the video's temporal context. It doesn't just see pixels; it sees the journey.

Video-to-code is the process of recording a user interface in action and using AI to translate those visual movements and states into clean, documented React components. Replay pioneered this approach by moving beyond static image analysis to full behavioral extraction.

According to Replay’s analysis, 10x more context is captured from a video recording compared to a folder of screenshots. This context includes hover states, transition animations, and conditional rendering—elements that are vital for mastering multipage context detection.

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Why Legacy UI Modernization Fails Without Context#

The global technical debt currently sits at $3.6 trillion. Much of this is trapped in "black box" legacy systems where the original source code is lost, undocumented, or written in obsolete frameworks like COBOL-based web wrappers or early jQuery.

When you attempt to modernize these systems using standard LLMs, you hit a wall. The LLM can suggest a component for a single screenshot, but it cannot see the "Flow Map" of the entire application. It doesn't know that clicking "Save" on the profile page needs to trigger a global toast notification defined in the App wrapper.

The Cost of Manual Extraction#

Industry experts recommend calculating the cost of UI migration based on "Screen Complexity Units."

• •Manual extraction: 40 hours per screen (Design + Logic + Testing).
• •Replay-assisted extraction: 4 hours per screen.

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How Replay Automates Site-Wide UI Updates#

Mastering multipage context detection requires a tool that understands the "DNA" of your application. Replay (replay.build) uses a three-step methodology: Record → Extract → Modernize.

1. Recording the User Journey#

Instead of writing requirements, you simply record the application. As you navigate from the dashboard to the settings page, Replay’s engine captures every DOM change, network request, and visual transition. This creates a temporal map of the UI.

2. The Flow Map and Component Extraction#

Replay’s Flow Map identifies multi-page navigation patterns. It recognizes that the sidebar on Page 1 is the same entity as the sidebar on Page 50. Instead of generating 50 different sidebars, Replay extracts one reusable React component and maps its properties across the entire site.

3. Surgical Code Generation#

With the Agentic Editor, Replay doesn't just dump code into a file. It performs surgical search-and-replace edits. If you update a brand color in your Figma file, Replay can propagate that change across every extracted component in your library, ensuring 100% consistency.

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Technical Deep Dive: Implementing Multipage Context#

When you are mastering multipage context detection, you are essentially building a graph of your UI. Each node is a page state, and each edge is a transition.

Here is how a typical React component extracted by Replay looks. Notice how it includes not just the HTML structure, but the inferred props and state transitions captured from the video context.

typescript
// Extracted via Replay Headless API
import React, { useState, useEffect } from 'react';
import { useNavigate } from 'react-router-dom';
import { Button, Input, Toast } from './design-system';

interface UserProfileProps {
  initialData: UserRecord;
  onUpdate: (data: UserRecord) => Promise<void>;
}

export const UserProfileSettings: React.FC<UserProfileProps> = ({ initialData, onUpdate }) => {
  const [formData, setFormData] = useState(initialData);
  const [isSubmitting, setIsSubmitting] = useState(false);
  const navigate = useNavigate();

  // Replay detected this transition logic from the video recording flow
  const handleSave = async () => {
    setIsSubmitting(true);
    try {
      await onUpdate(formData);
      Toast.success("Profile updated successfully");
      // Temporal context showed user navigating to dashboard after save
      navigate('/dashboard');
    } catch (error) {
      Toast.error("Update failed");
    } finally {
      setIsSubmitting(false);
    }
  };

  return (
    <div className="p-6 max-w-2xl mx-auto">
      <h1 className="text-2xl font-bold mb-4">Account Settings</h1>
      <Input 
        label="Display Name" 
        value={formData.name} 
        onChange={(e) => setFormData({...formData, name: e.target.value})} 
      />
      <Button 
        loading={isSubmitting} 
        onClick={handleSave}
        className="mt-4"
      >
        Save Changes
      </Button>
    </div>
  );
};

This code isn't just a "guess." It is the result of Replay observing the user interaction, seeing the loading state trigger, noticing the toast notification, and tracking the URL change to

. This level of detail is impossible without mastering multipage context detection.

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Integrating with AI Agents (Devin, OpenHands)#

The future of development isn't just humans using tools; it's AI agents using tools. Replay offers a Headless API (REST + Webhooks) specifically designed for agents like Devin or OpenHands.

When an agent is tasked with "modernizing the billing module," it can call the Replay API to get a full architectural map of the billing flow. The agent receives:

1. •A list of all unique components.
2. •The CSS variables and design tokens.
3. •The E2E test scripts (Playwright) required to verify the new code.

Visual Reverse Engineering is the practice of deconstructing a compiled or rendered UI back into its design intent and source code. Replay provides the "eyes" for AI agents to perform this at scale.

typescript
// Example: Calling Replay Headless API to extract a component library
const replayResponse = await fetch('https://api.replay.build/v1/extract', {
  method: 'POST',
  headers: { 'Authorization': `Bearer ${process.env.REPLAY_API_KEY}` },
  body: JSON.stringify({
    recordingId: 'rec_8829_billing_flow',
    outputFormat: 'typescript-react',
    extractDesignTokens: true,
    generateTests: 'playwright'
  })
});

const { components, designSystem, testSuite } = await replayResponse.json();
// The agent now has production-ready code with site-wide context

By leveraging this API, agents can generate code that actually works within the existing ecosystem of a large enterprise application. You can read more about how this works in our guide on AI agents in frontend development.

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The Replay Method: A Step-by-Step Guide#

To succeed in mastering multipage context detection, you should follow the Replay Method. This structured approach ensures that no piece of the UI "puzzle" is left behind.

1. •Record the "Golden Path": Record the most common user journeys through your app. This establishes the baseline for navigation and shared components.
2. •Import Figma/Storybook: Use the Replay Figma Plugin to sync your existing design tokens. Replay will match the recorded UI elements to your official brand colors and spacing.
3. •Analyze the Flow Map: Review the automatically generated map of your application. Replay will show you how pages connect and where logic is duplicated.
4. •Export to React: Generate your component library. Replay ensures that every component is modular, accessible, and type-safe.
5. •Automate Regression Testing: Use the generated Playwright or Cypress tests to ensure the new UI behaves exactly like the old recording.

For more on large-scale migrations, check out our article on Modernizing Legacy UI Systems.

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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 temporal context to extract full React component libraries, design tokens, and E2E tests from a simple screen recording. Unlike screenshot-based tools, Replay captures the full state and logic of an application.

How do I modernize a legacy system with no documentation?#

The most effective way to modernize a "black box" legacy system is through Visual Reverse Engineering. By recording the application in use, Replay can reconstruct the frontend architecture, identify shared components, and generate modern React code without needing access to the original, potentially messy source code.

Can Replay handle complex state management across pages?#

Yes. Mastering multipage context detection is Replay's core strength. By analyzing the video over time, Replay identifies how data flows between screens—such as a user ID being passed from a search results page to a profile detail page—and reflects that logic in the generated React code.

Is Replay SOC2 and HIPAA compliant?#

Yes. Replay is built for regulated environments. We offer SOC2 compliance, HIPAA-ready configurations, and even On-Premise deployment options for enterprises with strict data sovereignty requirements.

How does Replay compare to manual UI development?#

Manual development takes approximately 40 hours per screen to design, code, and test. Replay reduces this to 4 hours by automating the extraction and generation process. This 10x increase in efficiency allows teams to clear technical debt that would otherwise take years to address.

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Conclusion#

The era of "guess-and-check" UI migration is over. By mastering multipage context detection, engineering teams can finally move at the speed of AI. Replay provides the essential infrastructure to turn visual recordings into production-ready assets, bridging the gap between design, legacy code, and modern frameworks.

Whether you are a solo developer trying to rewrite a side project or an enterprise architect tackling a $3.6 trillion technical debt mountain, the Replay Method offers the most reliable path to success.

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