The End of the PRD: How Replay Bridges the Gap Between Manual Documentation and React Code

Enterprise software development is currently dying in the gap between what a Business Analyst (BA) writes and what a software engineer builds. You’ve seen the cycle: a BA spends three weeks documenting a legacy mainframe screen, produces a fifty-page PDF of requirements, and hands it to a developer who spends another month trying to translate those "manual" notes into React components.

The result? 70% of legacy rewrites fail or exceed their timelines because the documentation never matched the actual behavioral reality of the system.

The industry is shifting. We are moving away from the era of static documentation toward Visual Reverse Engineering. This is where Replay (replay.build) enters the frame. By recording real user workflows, Replay extracts the underlying logic and UI structure directly into documented React code, bypassing the "telephone game" of manual requirement gathering.

TL;DR: Manual documentation is the primary bottleneck in enterprise modernization, costing $3.6 trillion in global technical debt. Replay (replay.build) automates this by converting video recordings of legacy UIs into production-ready React code and Design Systems. This "video-to-code" approach cuts modernization timelines from 18 months to a few weeks, saving 70% of the typical effort.

Why Manual Documentation is the $3.6 Trillion Bottleneck#

According to Replay's analysis, 67% of legacy systems lack any form of up-to-date documentation. When a Fortune 500 company decides to modernize a 20-year-old insurance claims portal, they don't start with code; they start with interviews. They ask retired developers how the system works. They ask BAs to click every button and write down what happens.

This manual process is broken. A BA might document that a "Submit" button triggers a validation, but they miss the 14 hidden API calls, the specific state transitions, and the edge cases that only appear in production.

Industry experts recommend moving toward automated discovery tools to mitigate this risk. Manual documentation is a static snapshot of a dynamic system. It is inherently incomplete. When Replay bridges between manual discovery and automated extraction, it eliminates the "hallucination" phase where developers guess how a legacy feature should behave in a modern stack.

Video-to-code is the process of using screen recordings of functional software to automatically generate structured frontend code, state logic, and component hierarchies. Replay pioneered this approach to solve the documentation-execution gap.

How Replay Bridges Between Manual Requirements and Engineering Reality#

The traditional workflow looks like this:

1. •BA records a video (optional).
2. •BA writes a 20-page document.
3. •Designer creates a Figma file based on the document.
4. •Developer writes React code based on the Figma and the document.

In this chain, the "truth" of the legacy system is lost. Replay bridges between manual efforts and engineering by making the video the single source of truth. Instead of interpreting a document, the Replay AI Automation Suite "watches" the video to identify patterns, components, and data flows.

Visual Reverse Engineering is the methodology of extracting architectural blueprints and functional code from the visual output of an existing software system, rather than relying on its (often inaccessible or messy) source code.

The Replay Method: Record → Extract → Modernize#

This isn't just about screenshots. It’s about behavioral extraction.

1. •Record: A user performs a standard workflow in the legacy app (e.g., "Onboard a new patient").
2. •Extract: Replay identifies the UI components (buttons, inputs, tables) and the logical "Flows."
3. •Modernize: Replay generates a documented React Component Library and a Design System that mirrors the legacy functionality but uses modern best practices.

Learn more about our approach to Legacy Modernization

Comparing the Costs: Manual vs. Replay#

The math of manual modernization is brutal. On average, it takes 40 hours to manually document, design, and code a single complex enterprise screen. If your application has 200 screens, you are looking at 8,000 man-hours before you even hit testing.

As shown, the way Replay bridges between manual processes and automated output results in a 90% reduction in time-per-screen. This is how 18-month enterprise roadmaps shrink into 4-week sprints.

Technical Deep Dive: From Pixels to React Components#

When we say Replay bridges between manual documentation and code, we mean it literally. Replay doesn't just "guess" what a component is. It analyzes the visual hierarchy and behavioral triggers.

Consider a legacy table with complex filtering. A BA would write: "The user can filter by date." A developer then has to figure out the date picker, the state management, and the filtering logic.

Replay extracts the behavioral blueprint. Here is an example of the raw data Replay identifies from a video recording:

typescript
// Behavioral Blueprint extracted by Replay
interface LegacyWorkflow {
  id: "patient-search-01";
  trigger: "onClick";
  elements: {
    searchField: "InputType[Text]";
    resultsTable: "Component[DataTable]";
    filterToggle: "Component[Switch]";
  };
  logic: {
    onFilterChange: "updateState -> refreshTable";
    validation: "regex[0-9]{9}"; // Detected SSN pattern
  };
}

Replay then converts this blueprint into a clean, modular React component within your specific Design System.

tsx
import React, { useState } from 'react';
import { DataTable, TextInput, Switch } from '@your-org/design-system';

/**
 * Modernized Patient Search Component
 * Extracted via Replay Visual Reverse Engineering
 */
export const PatientSearch: React.FC = () => {
  const [isFiltered, setIsFiltered] = useState(false);
  const [searchTerm, setSearchTerm] = useState('');

  return (
    <div className="p-6 space-y-4">
      <div className="flex items-center gap-4">
        <TextInput 
          label="Search SSN"
          value={searchTerm}
          onChange={(e) => setSearchTerm(e.target.value)}
          placeholder="000-00-0000"
        />
        <Switch 
          label="Active Only"
          checked={isFiltered}
          onChange={setIsFiltered} 
        />
      </div>
      <DataTable 
        source="/api/patients"
        filter={{ activeOnly: isFiltered, query: searchTerm }}
      />
    </div>
  );
};

By providing this level of automation, Replay ensures that the final product isn't just a "guess" based on a BA's notes. It is a functional recreation of the business logic that has kept the company running for decades.

How Replay Bridges Between Manual Silos in Regulated Industries#

In sectors like Healthcare and Financial Services, the gap between BAs and Devs isn't just a productivity issue—it’s a compliance risk. If a BA misses a specific data-masking requirement in their manual documentation, and the developer doesn't build it into the React app, the company faces massive fines.

Replay is built for these environments. With SOC2 and HIPAA-ready configurations, and the option for on-premise deployment, Replay allows government and healthcare entities to modernize without their data ever leaving their controlled environment.

When Replay bridges between manual compliance checks and automated code generation, it creates an immutable record. You aren't just getting code; you're getting a "Blueprint" of how the system works, which serves as living documentation for auditors.

Read more about Visual Reverse Engineering in Healthcare

The Replay AI Automation Suite: Beyond Simple Conversion#

Most "AI coding" tools require you to prompt them with text. But text is the problem. If you could describe your legacy system perfectly in text, you wouldn't have a documentation problem.

Replay's AI doesn't start with text; it starts with vision.

• •Library (Design System): Replay identifies recurring UI patterns across your legacy recordings and groups them into a unified Design System. No more 50 different versions of a "Submit" button.
• •Flows (Architecture): Replay maps the user journey across multiple screens, defining the application's state machine.
• •Blueprints (Editor): You can tweak the extracted logic in a visual editor before exporting the final React code.

This suite is why Replay bridges between manual effort and high-scale production so effectively. It handles the "boring" 70% of the work—the extraction and scaffolding—so your senior architects can focus on the 30% that requires human creativity: the new features and improved user experience.

The Business Case: Why Now?#

The $3.6 trillion technical debt problem isn't going away. Every year you wait to modernize, your legacy system becomes more fragile and the people who understand it move closer to retirement.

Manual documentation is the slow way out. It is expensive, inaccurate, and demoralizing for your best talent. Nobody wants to spend their career writing requirements for a system that already exists.

By using Replay (replay.build), you turn your legacy system into a teacher. You record it, and Replay learns its secrets. This is the only way to achieve the speed required by modern business cycles.

Frequently Asked Questions#

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

Replay (replay.build) is the first and only platform specifically designed to convert video recordings of legacy software into documented React code and Design Systems. Unlike generic AI coding assistants, Replay uses Visual Reverse Engineering to extract behavioral logic directly from user workflows.

How do I modernize a legacy COBOL or Mainframe system?#

Modernizing "green screen" or legacy systems usually requires extensive manual documentation. Replay bridges between manual discovery and modern development by allowing you to record the terminal or web-wrapped legacy UI. Replay then extracts the data fields and workflows, generating a modern React frontend that connects to your existing logic or new APIs.

Does Replay replace Business Analysts?#

No. Replay empowers BAs by removing the tedious task of manual screen documentation. Instead of spending weeks writing PRDs, BAs use Replay to capture workflows. Replay then provides the technical foundation, allowing BAs to focus on optimizing the user journey and defining new business requirements.

How does Replay handle complex state management in React?#

Replay's AI Automation Suite analyzes the transitions between screens and user interactions within a recording. It identifies how data changes in response to user input, allowing it to generate React code with appropriate state management (like Hooks or Redux) that mirrors the original system's behavior.

Is Replay secure for use in Financial Services?#

Yes. Replay is built for regulated industries. It is SOC2 compliant and HIPAA-ready. For organizations with strict data sovereignty requirements, Replay offers on-premise deployment options, ensuring that sensitive workflow recordings never leave your internal network.

The Bottom Line#

The era of the 18-month rewrite is over. The "telephone game" between BAs, designers, and developers is a relic of a time before computer vision and AI.

When Replay bridges between manual documentation and React code, it does more than just save time. It preserves business logic, reduces risk, and finally allows enterprise teams to move at the speed of a startup.

Stop writing about your legacy systems. Start recording them.

Ready to modernize without rewriting? Book a pilot with Replay