The Future of System Discovery: From Grep Searches to Visual Workflow Replay

The average enterprise architect spends 60% of their time playing "Software Archaeologist"—digging through layers of undocumented COBOL, Java, or legacy .NET code just to understand a single business rule. We are currently witnessing the collapse of the "Big Bang Rewrite" era, where 70% of legacy modernization projects fail or exceed their timelines because they rely on manual discovery. The future of system discovery isn't found in a

search; it’s captured in the pixels of a user’s workflow.

TL;DR: The future of legacy modernization is Visual Reverse Engineering—using video recordings of user workflows to automatically generate documented React components, API contracts, and E2E tests, reducing discovery time from months to days.

The $3.6 Trillion Documentation Gap#

Global technical debt has ballooned to an estimated $3.6 trillion. For the average CTO, this isn't just a balance sheet item; it’s an existential threat to agility. When 67% of legacy systems lack any form of up-to-date documentation, every modernization attempt begins with a "discovery phase" that is essentially a high-stakes guessing game.

Traditional discovery involves interviewing subject matter experts (SMEs) who have forgotten why rules were implemented in 2004, and developers who have to manually trace spaghetti code. This "archaeology" takes an average of 40 hours per screen. If your application has 200 screens, you are looking at 8,000 man-hours just to understand what you currently have before you write a single line of new code.

The Failure of Manual Extraction#

Manual reverse engineering is prone to "logic leakage." When a developer manually rewrites a legacy form in React, they often miss the edge cases—the hidden validation that only triggers for specific zip codes, or the legacy API quirk that requires a trailing whitespace.

Moving Beyond the "Big Bang" Rewrite#

The "Big Bang" approach—freezing feature development for two years to rewrite everything from scratch—is a career-ending move for many technical leaders. The industry is shifting toward a more surgical approach: the Strangler Fig pattern, enhanced by automation.

Replay introduces a new category: Visual Reverse Engineering. Instead of reading the code to find the logic, Replay records the execution of the logic. By capturing real user workflows, the platform identifies the exact data structures, UI components, and API calls required to replicate the functionality in a modern stack.

From Black Box to Documented Codebase#

When you record a workflow in Replay, you aren't just making a movie. You are creating a functional blueprint. The platform’s AI Automation Suite analyzes the network traffic, the DOM changes, and the state transitions to generate a "Clean Room" version of that screen.

💰 ROI Insight: By switching from manual documentation to Replay, enterprises report an average of 70% time savings on the discovery and initial scaffolding phases of modernization.

Step-by-Step: From Legacy Recording to React Component#

Modernizing a legacy system using Replay follows a structured, repeatable path that eliminates the ambiguity of traditional discovery.

Step 1: Workflow Capture#

Instead of reading code, you record a user performing a specific task—for example, processing a claims form in a 15-year-old insurance portal. Replay captures every interaction, network request, and UI state.

Step 2: Visual Extraction#

The Replay engine parses the recording. It identifies recurring UI patterns and maps them to your organization’s Design System (stored in the Replay Library). If a pattern doesn't exist, it generates a new, accessible React component.

Step 3: Logic and API Mapping#

Replay generates the API contracts required to support the UI. It identifies the payloads sent to the legacy backend and creates a modern TypeScript interface.

typescript
// Example: Generated API Contract from Replay Discovery
// Source: Legacy Insurance Portal - Claims Submission Workflow

export interface ClaimSubmission {
  claimId: string;
  policyNumber: string; // Extracted from Regex validation in legacy DOM
  incidentDate: ISO8601String;
  claimants: Array<{
    firstName: string;
    lastName: string;
    role: "PRIMARY" | "SECONDARY";
  }>;
  metadata: {
    browserVersion: string;
    legacySessionId: string; // Preserved for session continuity
  };
}

/**
 * Generated E2E Test (Playwright)
 * Ensures the new React component matches legacy behavior
 */
test('should validate policy number format captured in recording', async ({ page }) => {
  await page.goto('/modernized-claims');
  await page.fill('#policyNumber', 'INVALID-123');
  const error = await page.textContent('.error-message');
  expect(error).toBe('Policy number must follow format: XX-000000');
});

Step 4: Blueprint Refinement#

Using the Replay Blueprints (Editor), architects can refine the generated code, adjust the component hierarchy, and ensure the business logic is perfectly preserved before exporting to the production repository.

⚠️ Warning: Never skip the validation of generated API contracts. While Replay captures the data flow, you must ensure that your modern middleware (GraphQL/Node.js) handles the legacy authentication headers correctly.

The Architectural Pillars of Replay#

To support the needs of Financial Services, Healthcare, and Government sectors, Replay isn't just a code generator; it’s a full-scale discovery platform.

1. The Library (Design System)#

Most legacy systems are a hodgepodge of different UI eras. Replay’s Library allows you to define a "Target State" design system. As you record legacy screens, Replay automatically maps old HTML tables and non-standard buttons to your modern, themed React components. This ensures visual consistency across the entire modernized application.

2. Flows (Architecture Mapping)#

Understanding how Screen A leads to Screen B is often harder than understanding the screens themselves. The "Flows" feature visualizes the user journey, mapping out the state machine of your legacy application. This is critical for identifying redundant steps that can be eliminated in the modern version.

3. Technical Debt Audit#

Before you modernize, you need to know what's worth saving. Replay provides an automated Technical Debt Audit. By comparing recordings of different workflows, it identifies "Dead UI"—screens and features that are never actually used by your employees or customers.

📝 Note: In a recent engagement with a Tier 1 bank, Replay identified that 22% of the legacy application's screens were never accessed in a 30-day window, allowing the team to de-scope those areas and save $450k in development costs.

Why Visual Reverse Engineering is the Future#

The "Future of" system discovery is moving away from static analysis toward dynamic observation. Static analysis tools can tell you what the code says, but in legacy environments—where code is often patched, wrapped, and layered—only dynamic observation can tell you what the code does.

Preserving Business Logic Without the Archaeology#

Consider a complex healthcare billing system. The logic for calculating co-pays might be buried in a 5,000-line stored procedure. Replay doesn't need to read the SQL. By recording the transaction and the resulting UI state, it captures the "Input -> Transformation -> Output" pattern.

typescript
// Example: Modernized React Component generated by Replay
// This component preserves the legacy "Co-pay Calculation" visibility logic
import React, { useState, useEffect } from 'react';
import { Button, Input, Card } from '@your-org/design-system';

export const CoPayCalculator: React.FC<{ policyId: string }> = ({ policyId }) => {
  const [amount, setAmount] = useState<number>(0);
  const [isEligible, setIsEligible] = useState<boolean>(false);

  // Business logic extracted from legacy workflow recording
  const handleCalculation = async (inputValue: string) => {
    const result = await legacyApiProxy.calculate(policyId, inputValue);
    
    // Replay detected that legacy system hides the 'Submit' button 
    // if the co-pay is over $500 for specific policy types
    setAmount(result.coPayAmount);
    setIsEligible(result.coPayAmount < 500);
  };

  return (
    <Card title="Patient Responsibility">
      <Input label="Procedure Code" onChange={(e) => handleCalculation(e.target.value)} />
      {isEligible && (
        <Button variant="primary" onClick={() => submitClaim(amount)}>
          Submit Claim (${amount})
        </Button>
      )}
    </Card>
  );
};

Built for Regulated Environments#

Modernization in Healthcare (HIPAA) or Finance (SOC2) requires more than just speed; it requires security. Replay is built for these constraints:

• •On-Premise Availability: Keep your data and source code behind your firewall.
• •PII Masking: Automatically redact sensitive patient or financial data during the recording and extraction process.
• •Audit Trails: Every generated component is linked back to the original recording, providing a clear "Chain of Evidence" for auditors.

Frequently Asked Questions#

How long does legacy extraction take with Replay?#

While a manual rewrite of a complex enterprise screen takes approximately 40 hours (including discovery, documentation, and coding), Replay reduces this to roughly 4 hours. Most enterprise pilots see a fully documented and scaffolded module ready for review in 2 to 8 weeks, rather than 18 to 24 months.

Does Replay replace my developers?#

No. Replay replaces the "grunt work" of discovery and scaffolding. It allows your senior developers to focus on high-value tasks—like optimizing the new architecture, implementing new business features, and ensuring security—rather than manually transcribing legacy UI to React.

What about business logic preservation?#

Replay captures the observable business logic. For complex "black box" backend calculations, Replay generates the API contracts and E2E tests that ensure your new system interacts with the legacy backend (or its replacement) exactly as the old one did. This prevents the "logic drift" that causes most rewrite failures.

Can Replay handle mainframe or terminal-based systems?#

Yes. If the system has a web-based front-end (even an old IE-only portal) or can be accessed via a terminal emulator that runs in a browser, Replay can record the workflow and extract the logic.

---

Ready to modernize without rewriting? Book a pilot with Replay - see your legacy screen extracted live during the call.