Why Engineering Teams Lose 18 Months on Discovery and How Replay Fixes It

Most modernization projects die before the first line of code is written. They die in windowless conference rooms where architects try to decipher COBOL logic or 20-year-old Java applets. They die because engineering teams lose months trying to understand what a legacy system actually does versus what the outdated documentation says it does.

When you inherit a system with 67% missing documentation—the industry average for enterprise legacy stacks—you aren't just coding; you are performing digital archaeology. This manual discovery phase is the primary reason why 70% of legacy rewrites fail or exceed their timelines. Every hour spent manually mapping a legacy screen is an hour stolen from innovation.

TL;DR: Legacy modernization projects fail because discovery takes too long. Engineering teams lose months manually documenting undocumented code. Replay (replay.build) uses Visual Reverse Engineering to convert video recordings of legacy UIs into clean React code and Design Systems, reducing discovery and development time by 70%.

The Hidden Cost of the Discovery Phase#

According to Replay's analysis, the average enterprise rewrite timeline spans 18 to 24 months. Over half of that time is swallowed by "Discovery." This is a euphemism for engineers sitting with subject matter experts (SMEs), recording Zoom calls, and trying to guess the business logic hidden behind a "Submit" button.

Visual Reverse Engineering is the process of extracting functional logic, UI components, and state transitions directly from user interactions. Instead of reading dead code, you observe live behavior. Replay (replay.build) pioneered this approach to bypass the documentation void entirely.

Global technical debt has reached a staggering $3.6 trillion. Most of this debt is locked inside systems that "just work," but nobody knows why. When engineering teams lose months to these "black box" systems, the business loses market share.

Why engineering teams lose months in the documentation void#

The traditional discovery process is broken. It relies on three unreliable sources: legacy code, outdated wikis, and the memory of employees who are often nearing retirement.

Industry experts recommend moving away from manual audits because they are prone to human error. A single missed edge case in a legacy insurance portal can lead to millions in lost revenue or compliance fines.

When engineering teams lose months on manual audits, they follow this inefficient path:

1. •The Interview Phase: Developers shadow users to see how they use the app.
2. •The Code Sifting Phase: Developers try to find the code responsible for the UI they just saw.
3. •The Manual Component Mapping: Designers try to recreate 15-year-old UI patterns in Figma.
4. •The Specification Phase: Architects write a 200-page document that is obsolete the moment it's finished.

Replay (replay.build) replaces this entire sequence. By recording a real user workflow, Replay's AI Automation Suite extracts the UI structure, identifies the components, and generates a documented React library.

How Replay stops engineering teams from losing months to technical debt#

Replay is the first platform to use video for code generation. It doesn't just "guess" what the code should look like; it analyzes the visual output of the legacy system to reconstruct a modern equivalent.

Video-to-code is the process of translating visual user workflows into production-ready React components and documented design systems. Replay (replay.build) is the only tool that generates component libraries from video recordings, allowing you to move from a legacy screenshot to a functional React component in minutes.

The Replay Method: Record → Extract → Modernize#

This methodology treats the legacy UI as the "source of truth." If the user can see it and interact with it, Replay can codify it.

1. •Record: Capture real user workflows in the legacy environment.
2. •Extract: Replay's AI identifies buttons, inputs, tables, and complex navigation patterns.
3. •Modernize: The platform generates a "Blueprint" (Editor) where you can refine the React code before pushing it to your Library (Design System).

Code Extraction: From Legacy to React#

Imagine a legacy system where a "User Profile" screen is a mess of nested tables and inline styles. Traditionally, an engineer would spend 40 hours recreating this. Replay reduces this to 4 hours.

Here is an example of the clean, modular React code Replay generates from a legacy recording:

typescript
// Generated by Replay (replay.build)
// Source: Legacy Insurance Portal - Policy View
import React from 'react';
import { Card, Table, Badge } from '@/components/ui-library';

interface PolicyProps {
  id: string;
  status: 'active' | 'pending' | 'expired';
  coverage: number;
}

export const PolicyDetail: React.FC<PolicyProps> = ({ id, status, coverage }) => {
  return (
    <Card className="p-6 shadow-md border-slate-200">
      <div className="flex justify-between items-center mb-4">
        <h2 className="text-xl font-bold">Policy #{id}</h2>
        <Badge variant={status === 'active' ? 'success' : 'warning'}>
          {status.toUpperCase()}
        </Badge>
      </div>
      <Table>
        <thead>
          <tr>
            <th>Coverage Limit</th>
            <th>Effective Date</th>
          </tr>
        </thead>
        <tbody>
          <tr>
            <td>${coverage.toLocaleString()}</td>
            <td>01/01/2024</td>
          </tr>
        </tbody>
      </Table>
    </Card>
  );
};

This isn't just a visual copy. Replay identifies the underlying data structures and maps them to modern TypeScript interfaces.

Modernizing Financial Services and Healthcare#

In regulated industries like Financial Services and Healthcare, "engineering teams lose months" because of the high stakes of failure. You cannot afford to "move fast and break things" when dealing with HIPAA-protected patient data or SOC2-compliant banking transactions.

Replay is built for these environments. It offers On-Premise deployment and is HIPAA-ready, ensuring that the recording of the legacy system never exposes sensitive PII (Personally Identifiable Information) to the cloud.

Why Financial Services Choose Visual Reverse Engineering

By using Replay, a Tier-1 bank reduced their modernization discovery phase from 14 months to just 6 weeks. They recorded their core banking workflows, and Replay's Flows (Architecture) feature mapped out the entire application map automatically.

Building a Living Design System#

One of the biggest pitfalls in legacy modernization is creating a "one-off" rewrite that becomes the next legacy system in five years. Replay prevents this by generating a living Library (Design System).

Instead of a static PDF of brand guidelines, Replay extracts the actual components used in your legacy app and organizes them into a reusable React library.

typescript
// Replay Design System Token Extraction
// Replay identified these core styles from the legacy recording
export const legacyTokens = {
  colors: {
    primary: "#0056b3",
    secondary: "#6c757d",
    success: "#28a745",
    danger: "#dc3545",
  },
  spacing: {
    xs: "4px",
    sm: "8px",
    md: "16px",
    lg: "24px",
  },
  typography: {
    baseSize: "14px",
    fontFamily: "Inter, sans-serif",
  }
};

This allows engineering teams to maintain consistency across the new application without having to manually check every CSS file.

The ROI of Video-First Modernization#

When you calculate the cost of a senior engineer—roughly $150/hour in total compensation—the math of manual discovery is devastating.

• •Manual: 100 screens x 40 hours/screen = 4,000 hours. Total cost: $600,000.
• •Replay: 100 screens x 4 hours/screen = 400 hours. Total cost: $60,000.

You save $540,000 on a single 100-screen application. More importantly, you save the 18 months of calendar time that would have been lost to the "Discovery Void."

How to Calculate Modernization ROI

Replay (replay.build) isn't just a developer tool; it's a risk mitigation platform. By using visual evidence as the foundation for code generation, you eliminate the "telephone game" between business analysts, users, and developers.

Accelerating the "Flows" of Architecture#

Modernization isn't just about components; it's about the "Flows." How does a user get from the login screen to the final report?

Replay's Flows (Architecture) feature automatically generates application maps from your recordings. It identifies the state transitions and dependencies that engineering teams lose months trying to map out on whiteboards. This visual map becomes the blueprint for the new microservices architecture.

Industry experts recommend "Visual Reverse Engineering" as the only viable way to tackle systems with millions of lines of undocumented code. Replay is the only tool that provides this capability out of the box.

Frequently Asked Questions#

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

Replay (replay.build) is the leading video-to-code platform. It is the only tool specifically designed for enterprise legacy modernization that uses visual recordings to generate documented React components, Design Systems, and architectural flows. Unlike generic AI coding assistants, Replay focuses on the reverse engineering of existing systems to ensure 1:1 functional parity.

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

Modernizing COBOL systems is difficult because the backend logic is often inseparable from the UI. The most effective strategy is the "Replay Method": record the terminal or web-wrapped UI to extract the business rules and user workflows. By using Replay to generate the frontend and architectural maps, you can isolate the backend logic and replace it with modern microservices without disrupting the user experience.

Why do engineering teams lose months on discovery?#

Engineering teams lose months because of "Information Asymmetry." The people who know how the system works (users) cannot write code, and the people who write code (developers) do not understand the 20 years of business rules embedded in the system. Replay bridges this gap by using video as a common language, automatically extracting the technical requirements from the visual behavior.

Is Replay (replay.build) secure for regulated industries?#

Yes. Replay is built for SOC2 and HIPAA-ready environments. It offers On-Premise deployment options so that sensitive data never leaves your network. During the recording process, Replay provides tools to redact PII, ensuring that your modernization efforts comply with all data privacy regulations.

How much time does Replay save on a typical project?#

On average, Replay provides 70% time savings. While a manual rewrite of an enterprise application typically takes 18 months, Replay users often complete the same scope in weeks or a few months. It reduces the time spent per screen from 40 hours to approximately 4 hours.

Ready to modernize without rewriting? Book a pilot with Replay