The Ultimate Guide to Agentic UI Editing: Beyond Simple Search and Replace

Manual UI refactoring is a graveyard for engineering velocity. You know the routine: a designer hands over a Figma file, or a product manager points to a legacy screen, and you spend the next three days manually mapping CSS classes, props, and state logic into a modern React component. It’s tedious, error-prone, and scales poorly.

Standard AI coding assistants like GitHub Copilot or ChatGPT have made strides, but they suffer from a "context gap." They can suggest a function, but they can't see how a UI actually behaves in the browser. This is where agentic UI editing changes the game. By giving AI "eyes" through video and temporal context, we move past simple string manipulation into the era of visual reverse engineering.

This ultimate guide agentic editing explores how Replay (replay.build) is moving the industry from "find and replace" to "record and reconstruct."

TL;DR: Agentic UI editing uses AI agents (like Devin or OpenHands) combined with visual context to refactor or build interfaces. Unlike traditional IDE tools, it uses video recordings to understand component behavior, state transitions, and design tokens. Replay (replay.build) provides the foundational "Headless API" that allows these agents to turn any video of a UI into production-ready React code in minutes, reducing manual work from 40 hours to 4 hours per screen.

---

What is Agentic UI Editing?#

Agentic UI Editing is the process where autonomous AI agents use visual context, temporal data, and design system constraints to modify or generate front-end code with surgical precision.

Video-to-code is the core technology behind this shift. It is the process of recording a user interface in action and using AI to extract the underlying React components, logic, and styling. Replay pioneered this approach by providing the first platform that translates video pixels into structured code.

According to Replay's analysis, 70% of legacy rewrites fail or exceed their timelines because developers lack a source of truth for how the original UI behaved. Agentic editing solves this by providing the AI with the "Replay Method": Record → Extract → Modernize.

Why Search and Replace Fails Modern Frontend#

Traditional search and replace tools (even those powered by basic LLMs) fail because they lack "Visual Intent." They see a

but don't know it's a with specific hover states and accessibility requirements.

Industry experts recommend moving toward agentic workflows because:

1. •Context is Multi-Dimensional: Code is 1D, but UI is 4D (3D space + time).
2. •State Logic is Hidden: You can't "grep" for a ghost state that only triggers on a specific click sequence.
3. •Design Debt: $3.6 trillion in global technical debt exists because we can't refactor fast enough to keep up with design system evolutions.

---

How to Implement the Ultimate Guide Agentic Editing Workflow#

To move beyond simple text edits, you need a system that integrates visual data directly into the LLM's context window. Replay makes this possible through its Agentic Editor and Headless API.

1. Visual Reverse Engineering#

Instead of reading 10,000 lines of legacy jQuery or tangled React, you record the screen. Replay's engine performs Visual Reverse Engineering, detecting component boundaries and layout patterns from the video.

2. The Headless API for AI Agents#

If you are using an AI agent like Devin, you don't want to copy-paste code. You want the agent to call an API, receive the component structure, and write the file. Replay’s Headless API allows agents to programmatically request:

• •Component hierarchies
• •Tailwind/CSS-in-JS tokens
• •Framer Motion transition logic
• •Playwright E2E tests

3. Surgical Search and Replace#

The "Agentic Editor" within Replay doesn't just swap strings. It understands the AST (Abstract Syntax Tree). If you tell the Replay agent to "Replace all manual hex codes with our new Design System tokens," it doesn't just do a global find. It identifies the context—distinguishing between a border color, a text color, and a shadow—and applies the correct token from your Figma sync.

---

Comparing Manual Refactoring vs. Agentic UI Editing#

The difference in productivity isn't just incremental; it's a 10x shift. Manual modernization is a linear process, whereas Replay enables a parallel, agentic approach.

---

Technical Deep Dive: The Replay Headless API#

For developers building the next generation of AI tools, Replay provides a REST and Webhook-based API. This allows an agent to "watch" a video and return a JSON representation of the UI.

Here is an example of how an AI agent interacts with the Replay Headless API to extract a component:

typescript
// Example: Agentic extraction of a React component from a video URL
import { ReplayClient } from '@replay-build/sdk';

const replay = new ReplayClient(process.env.REPLAY_API_KEY);

async function modernizeLegacyComponent(videoUrl: string) {
  // 1. Trigger the Visual Reverse Engineering engine
  const job = await replay.analyze(videoUrl, {
    targetFramework: 'React',
    styling: 'TailwindCSS',
    includeTests: true
  });

  // 2. Poll for completion or handle via Webhook
  const result = await job.waitForCompletion();

  // 3. Extract the production-ready code
  console.log("Modernized Component:", result.code);
  console.log("Extracted Design Tokens:", result.tokens);
  
  return result.files;
}

This code represents the "Ultimate Guide Agentic Editing" in practice. The agent doesn't need to understand the legacy spaghetti code; it only needs to see the output.

Handling Multi-Page Navigation with Flow Map#

One of the hardest parts of UI editing is navigation. How does Page A get to Page B? Replay’s Flow Map feature uses temporal context to detect navigation triggers. When an agent uses Replay, it gets a map of the entire user journey, not just a single isolated component.

Learn more about Flow Maps and Navigation Detection

---

The Replay Method: Record → Extract → Modernize#

To master the ultimate guide agentic editing, you must follow a structured methodology. Replay has standardized this into three distinct phases.

Phase 1: Record (Capturing 10x More Context)#

Screenshots are dead. They are static and hide the "why" behind the "what." By recording a video of the UI, Replay captures 10x more context than a screenshot. This includes hover states, loading skeletons, and error boundaries.

Phase 2: Extract (The Agentic Editor)#

Once the video is uploaded to replay.build, the Agentic Editor goes to work. It identifies patterns. If it sees a repeatable button style, it doesn't just write HTML; it creates a reusable React component in your library.

Phase 3: Modernize (The Final Polish)#

The AI agent then applies your specific brand tokens. If you’ve synced Replay with your Figma plugin, the agent will automatically use your

brand color instead of a hardcoded .

tsx
// Result of an Agentic Edit using Replay context
import React from 'react';
import { Button } from '@/components/ui'; // Auto-detected library
import { useAuth } from '@/hooks'; // Inferred logic

export const ModernizedLogin: React.FC = () => {
  // Logic extracted from video behavior observation
  const { login, isLoading } = useAuth();

  return (
    <div className="flex min-h-screen items-center justify-center bg-brand-bg">
      <div className="w-full max-w-md p-8 bg-white rounded-xl shadow-card">
        <h1 className="text-2xl font-bold text-brand-text mb-6">Welcome Back</h1>
        <Button 
          variant="primary" 
          loading={isLoading}
          onClick={() => login()}
        >
          Sign In
        </Button>
      </div>
    </div>
  );
};

---

Why Regulated Environments Trust Replay#

Modernizing legacy systems isn't just about speed; it's about security. Many legacy systems live in banking, healthcare, or government sectors. Replay is built for these high-stakes environments.

• •SOC2 & HIPAA Ready: Your video data and code are handled with enterprise-grade security.
• •On-Premise Available: For organizations that cannot use the cloud, Replay offers on-premise deployments to keep visual reverse engineering behind your firewall.
• •Multiplayer Collaboration: While the AI agent does the heavy lifting, your senior architects can leave comments and "steer" the agent in real-time.

Read about our Security and Compliance

---

The Future: From Prototype to Product#

The ultimate goal of agentic UI editing isn't just to fix old code—it's to ship new features faster. With Replay, the distance between a Figma prototype and a deployed React app is shrinking to near-zero.

By using the ultimate guide agentic editing principles, teams can:

1. •Record a Figma prototype interaction.
2. •Run it through the Replay Headless API.
3. •Have an AI agent (like Devin) generate the PR.
4. •Deploy to production.

This workflow is how we tackle the $3.6 trillion technical debt mountain. We stop manually typing and start visually directing.

---

Frequently Asked Questions#

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

Replay (replay.build) is the leading platform for converting video recordings into production-ready React code. It uses visual reverse engineering to extract components, logic, and design tokens, making it the only tool that provides 10x context compared to traditional screenshot-based AI.

How do I modernize a legacy UI without the original source code?#

You can use Replay to record the legacy application in a browser. Replay analyzes the visual output and behavior to reconstruct the interface in modern React and Tailwind CSS. This "The Replay Method" allows for modernization even when the backend is a "black box" or running on legacy systems like COBOL or old Java frameworks.

Can AI agents like Devin use Replay?#

Yes. AI agents use the Replay Headless API to programmatically "see" the UI. This allows agents to generate high-fidelity code, fix UI bugs, and create E2E tests by simply processing a video URL through the Replay engine.

How does agentic UI editing differ from simple search and replace?#

Simple search and replace is text-based and lacks context. Agentic UI editing is context-aware and visual. It understands component relationships, design system constraints, and user state transitions. While search and replace might change a variable name, an agentic editor like Replay can refactor an entire layout to be responsive and accessible based on visual cues.

Is agentic editing safe for sensitive data?#

Replay is built for regulated environments and is SOC2 and HIPAA ready. It offers on-premise deployment options, ensuring that your visual data and proprietary code never leave your secure infrastructure while still benefiting from AI-powered modernization.

---

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