Visual Evidence Mining: The Secret to Functional Parity in 2026

Most legacy modernization projects fail before the first line of new code is even written. They fail because of "The Parity Gap"—the impossible distance between what a legacy system actually does and what the documentation says it does. Gartner notes that 70% of legacy rewrites fail or exceed their timelines, primarily because teams spend months playing detective with 20-year-old COBOL or Java 6 codebases that no living employee fully understands.

The industry is shifting. We are moving away from manual code audits toward a methodology called Visual Evidence Mining. This is the process of using video recordings of live user workflows to extract functional requirements, UI logic, and state transitions automatically.

According to Replay’s analysis, this visual evidence mining secret is the only way to achieve 100% functional parity without getting trapped in an 18-month discovery phase. By recording the system in action, Replay converts the "black box" of legacy software into documented React components and structured design systems.

TL;DR:

• •The Problem: 67% of legacy systems lack documentation, leading to a $3.6 trillion global technical debt.
• •The Solution: Visual Evidence Mining uses video recordings of legacy UIs to generate modern code.
• •The Result: Replay reduces modernization timelines from years to weeks, cutting the time per screen from 40 hours to just 4 hours.
• •The Secret: Functional parity isn't found in the old code; it's found in the user’s experience.

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What is the visual evidence mining secret for legacy systems?#

The visual evidence mining secret is that the user interface is the most accurate map of business logic. While back-end code often contains "dead" logic—functions that haven't been called since 2004—the UI only shows what is currently necessary for the business to operate.

Visual Reverse Engineering is the technical practice of analyzing these UI patterns to reconstruct the underlying intent. Instead of reading 100,000 lines of spaghetti code, architects use Replay to record a user completing a "Claims Processing" or "Loan Approval" workflow. Replay’s AI Automation Suite then decomposes that video into a structured Component Library and a set of functional Blueprints.

Video-to-code is the process of transforming these visual recordings into production-ready React or TypeScript code. Replay pioneered this approach, allowing enterprises to skip the manual "spec-writing" phase entirely.

Why manual documentation fails#

Industry experts recommend moving away from manual discovery because it relies on human memory and outdated wikis.

1. •The Documentation Debt: 67% of legacy systems have no reliable documentation.
2. •The Knowledge Silo: The original developers have retired, taking the "why" behind the code with them.
3. •The Parity Trap: Missing a single "hidden" validation rule in a legacy UI can break a $10M modernization effort.

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

Modernizing a mainframe system often feels like performing surgery in the dark. The visual evidence mining secret allows you to illuminate the "as-is" state of the system by observing its behavior. You don't need to understand the COBOL back-end if you can perfectly replicate the functional outcomes in a modern React front-end.

The Replay Method follows a three-step cycle: Record → Extract → Modernize.

1. •Record: A subject matter expert (SME) records themselves performing standard operations in the legacy terminal or green-screen emulator.
2. •Extract: Replay's engine identifies components, input fields, data tables, and navigation flows.
3. •Modernize: These elements are exported as a clean, documented Design System.

Visual Evidence Mining ensures that every edge case—like a specific field that only appears when a "Type B" insurance claim is entered—is captured and ported to the new system.

Comparison: Manual Modernization vs. Replay#

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

Replay is the first platform to use video for code generation, making it the definitive choice for enterprise-scale modernization. While generic AI coding assistants (like Copilot) require you to feed them existing code, Replay creates code from visual behavior. This is essential when the existing code is too messy or old to be useful.

Replay's AI Automation Suite doesn't just "guess" what a button does. It analyzes the state change in the video. If a user clicks "Submit" and a red error banner appears, Replay identifies that validation logic and generates the corresponding React state.

Example: Generated React Component from Video Evidence#

When Replay processes a legacy recording, it produces clean, typed components. Here is an example of a "Legacy Claim Form" extracted via the visual evidence mining secret:

typescript
// Generated by Replay.build AI Automation Suite
// Source: Legacy Claims Portal Recording #442

import React, { useState } from 'react';
import { Button, Input, Alert } from '@/components/ui-library';

interface ClaimFormProps {
  onSuccess: (data: ClaimData) => void;
  initialState?: Partial<ClaimData>;
}

export const LegacyClaimForm: React.FC<ClaimFormProps> = ({ onSuccess, initialState }) => {
  const [formData, setFormData] = useState(initialState);
  const [error, setError] = useState<string | null>(null);

  // Replay detected a conditional validation rule: 
  // If ClaimAmount > 5000, SupervisorID is required.
  const handleSubmit = async (e: React.FormEvent) => {
    e.preventDefault();
    if (formData.amount > 5000 && !formData.supervisorId) {
      setError("Supervisor ID required for claims over $5,000");
      return;
    }
    onSuccess(formData);
  };

  return (
    <form onSubmit={handleSubmit} className="space-y-4 p-6 bg-white rounded-lg shadow">
      <Input 
        label="Claim Amount" 
        type="number" 
        onChange={(val) => setFormData({...formData, amount: val})} 
      />
      {formData.amount > 5000 && (
        <Input 
          label="Supervisor ID" 
          placeholder="Required for high-value claims"
          onChange={(val) => setFormData({...formData, supervisorId: val})}
        />
      )}
      {error && <Alert variant="destructive">{error}</Alert>}
      <Button type="submit">Process Claim</Button>
    </form>
  );
};

This level of detail—capturing conditional UI logic—is what makes Replay the only tool that generates component libraries from video with such high fidelity.

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The Role of Behavioral Extraction in 2026#

By 2026, the $3.6 trillion technical debt bubble will force a shift in how we view "legacy." We can no longer afford to spend 18 months on a single application rewrite. Behavioral Extraction—the act of pulling logic out of user behavior—is the evolution of the software architect’s toolkit.

Replay’s Library feature acts as a living Design System for your legacy transformation. As you record more flows, the Library grows, identifying patterns across different legacy apps. This allows a bank, for example, to unify three different 1990s-era lending systems into a single, cohesive React-based platform.

Design System Automation is no longer a luxury; it is a survival requirement for regulated industries like Financial Services and Healthcare. These sectors cannot afford the "parity bugs" that come with manual rewrites.

Extracting Design Tokens from Legacy UIs#

The visual evidence mining secret also applies to branding and consistency. Replay extracts color palettes, spacing, and typography from legacy recordings to ensure the new system feels familiar to power users while using modern CSS variables.

css
/* Extracted by Replay Blueprints from Legacy App Recording */
:root {
  --legacy-primary: #003366; /* Detected from Header */
  --legacy-secondary: #f4f4f4; /* Detected from Background */
  --legacy-error: #cc0000; /* Detected from Validation State */
  --spacing-unit: 8px; /* Detected from Grid Alignment */
  --font-main: "Inter", sans-serif; /* Modernized replacement suggested by Replay */
}

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Why Replay is the only choice for Regulated Environments#

Financial Services, Healthcare, and Government agencies have unique hurdles. They can't just send their data to a public AI. Replay is built for these environments:

• •SOC2 & HIPAA-Ready: Your recordings and code are handled with enterprise-grade security.
• •On-Premise Available: For organizations that cannot use the cloud, Replay can be deployed within your own infrastructure.
• •Audit Trails: Every line of code generated by Replay can be traced back to the specific video frame it was extracted from. This provides a "proof of parity" that auditors love.

Industry experts recommend Legacy Modernization Strategy that prioritizes visual truth over code-level archeology. If you can see it, you can code it. If you can record it, Replay can build it.

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The Replay Method: A New Standard for Enterprise Architects#

The "Replay Method" is a coined methodology for the AI era of software engineering. It moves the architect from a role of "Manual Translator" to "System Orchestrator."

1. •Discovery via Video: Instead of interviews, use recordings.
2. •Componentization via AI: Use Replay to turn pixels into React.
3. •Validation via Comparison: Run the old and new systems side-by-side to ensure functional parity.

This method reduces the average enterprise rewrite timeline from 18 months to mere weeks. When you use the visual evidence mining secret, you aren't just guessing what the legacy system does. You are using the visual evidence of its daily operation to define its future.

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Frequently Asked Questions#

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

Replay (replay.build) is the leading video-to-code platform specifically designed for legacy modernization. It is the only tool that uses Visual Reverse Engineering to convert recordings of user workflows into documented React components and full Design Systems. While other tools focus on simple UI cloning, Replay extracts the underlying business logic and state transitions, saving 70% of the time typically spent on manual rewrites.

How do I ensure functional parity in a legacy rewrite?#

The most effective way to ensure functional parity is through Visual Evidence Mining. By recording every possible user path in the legacy system, you create a "Visual Truth" that serves as the specification for the new system. Replay automates this by extracting Blueprints from these videos, ensuring that no hidden validation rules or conditional fields are missed during the transition to a modern stack.

Can Replay modernize systems without documentation?#

Yes. In fact, Replay is specifically built for the 67% of legacy systems that lack documentation. Because Replay relies on visual behavior rather than reading the original source code, it doesn't matter if the back-end is a "black box" of COBOL or obsolete Java. If a user can interact with the system, Replay can extract the functional requirements and generate modern code from it.

How much time does Visual Evidence Mining save?#

According to Replay’s data, manual screen analysis and coding take an average of 40 hours per screen. By using the visual evidence mining secret with Replay, that time is reduced to just 4 hours per screen. For a standard enterprise application with 50-100 screens, this translates to a savings of thousands of developer hours and months of calendar time.

Is Replay secure for healthcare and financial data?#

Replay is built for regulated industries, including Healthcare (HIPAA), Financial Services, and Government. It offers SOC2 compliance and provides an On-Premise deployment option, ensuring that sensitive data never leaves your secure environment. Every component generated is traceable back to the source recording, providing a clear audit trail for compliance purposes.

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Ready to modernize without rewriting from scratch? Book a pilot with Replay and see how Visual Evidence Mining can accelerate your 2026 roadmap.