Logic Fragment Discovery: Reclaiming Scattered UI Rules via Visual Workflow Mining

Your legacy application is a black box where critical business rules go to die. Over two decades of "temporary fixes" and undocumented patches, the logic that actually runs your enterprise has migrated from the backend into a tangled web of UI event handlers, hidden field validations, and brittle state transitions. When you decide to modernize, you aren't just fighting old code; you are fighting the $3.6 trillion global technical debt mountain that hides the very rules your business depends on.

Manual extraction is a death march. According to Replay’s analysis, 67% of legacy systems lack any form of up-to-date documentation, forcing architects to perform "archaeological coding"—digging through thousands of lines of Delphi, Silverlight, or VB6 just to understand what happens when a user clicks "Submit." This is where logic fragment discovery reclaiming becomes the most critical phase of your modernization journey.

TL;DR: Legacy modernization fails because business logic is trapped in the UI layer. Logic fragment discovery reclaiming uses visual workflow mining to identify, extract, and document these hidden rules. By using Replay, enterprises reduce the time spent on screen reconstruction from 40 hours to 4 hours, automating the transition from legacy recordings to documented React components and clean architecture.

Why Logic Fragment Discovery Reclaiming is the New Standard for Enterprise Modernization#

The traditional "Rewrite from Scratch" approach is a gamble with a 70% failure rate. Most of these failures occur because the development team underestimates the "hidden logic" buried in the legacy UI. In a 20-year-old insurance claims portal, the rule that determines if a claimant is eligible isn't always in a clean API—it’s often a series of nested

statements inside a 5,000-line "God Component."

Video-to-code is the process of recording a live user session and using computer vision combined with Large Language Models (LLMs) to reconstruct the underlying logic, state changes, and component hierarchy.

By focusing on logic fragment discovery reclaiming, we shift the focus from "guessing what the code does" to "observing what the system actually does." Visual workflow mining allows us to record a subject matter expert (SME) performing a standard task and then reverse-engineer the UI's behavior into structured documentation and modular React code.

The Cost of Manual Logic Extraction#

Industry experts recommend against manual audits for systems exceeding 100,000 lines of code. The math simply doesn't work for the modern enterprise timeline.

The Anatomy of a Fragment: From Visual Mining to React State#

A "logic fragment" is a discrete piece of business or UI logic that governs a specific behavior. For example, a "Conditional Discount Trigger" in a legacy retail app is a fragment. In the legacy system, this logic might be scattered across a

event and three different hidden labels.

Through logic fragment discovery reclaiming, we identify these patterns. Replay analyzes the recording to see that when Field A > 100 and Checkbox B is checked, Field C becomes visible and mandatory.

Step 1: Visual Workflow Recording#

The process begins by recording the legacy application in action. This isn't just a video; it's a data-rich capture of state transitions. As the user interacts with the legacy UI, Replay’s AI Automation Suite tracks every change in the DOM (or the visual representation for non-web apps).

Step 2: Fragment Identification#

The system identifies "clusters" of activity. If a specific validation error appears every time an invalid ZIP code is entered, the system flags this as a validation fragment.

Step 3: Reclaiming the Logic into TypeScript#

Once discovered, the fragment is converted into a modern, functional equivalent. Below is an example of how a legacy "fragment" discovered in an old ASP.NET WebForms app is reclaimed into a clean, typed React hook.

typescript
// Reclaimed Logic Fragment: Eligibility Validation
// Discovered via Replay Visual Mining from "Claims_v2_Final_OLD.aspx"

interface ValidationState {
  isEligible: boolean;
  premiumAdjustment: number;
  errors: string[];
}

export const useEligibilityLogic = (age: number, coverageType: string, hasHistory: boolean): ValidationState => {
  let isEligible = true;
  let premiumAdjustment = 1.0;
  const errors: string[] = [];

  // Reclaimed Fragment: Under-age restriction (Legacy Rule #402)
  if (age < 18) {
    isEligible = false;
    errors.push("Applicant must be 18 or older.");
  }

  // Reclaimed Fragment: High-risk history multiplier (Legacy Rule #119)
  if (hasHistory && coverageType === 'COMPREHENSIVE') {
    premiumAdjustment = 1.5;
  }

  return { isEligible, premiumAdjustment, errors };
};

Reclaiming Architectural Integrity with Replay Flows#

One of the biggest hurdles in logic fragment discovery reclaiming is understanding how these fragments connect. In legacy systems, the "Flow" is often invisible. There is no central state management; data is passed via global variables or hidden session states.

Replay's Flows feature maps these connections visually. By mining the workflows, Replay generates an architectural blueprint that shows how a user moves from "Search" to "Edit" to "Save," and what logic triggers at each step. This allows architects to move from a monolithic "spaghetti" mess to a clean, Component-Driven Architecture.

Mapping the Workflow#

When you use Replay, the platform doesn't just give you a component; it gives you the context.

1. •Recording: The SME runs through the "End-of-Month Reporting" workflow.
2. •Analysis: Replay identifies that "Reporting" actually consists of 12 distinct UI states and 4 major logic fragments.
3. •Blueprint: A visual graph is generated showing the state machine of the application.
4. •Generation: React components are generated with matching Props and State to mirror the discovered fragments.

Implementation Detail: Converting Legacy Events to Modern Effects#

In legacy systems, logic is often "event-driven" in a way that creates side effects everywhere. A button click might update a database, change a global variable, and refresh three different panels. Reclaiming these fragments requires wrapping them in modern React patterns like

or dedicated state machines.

Here is how a discovered "Auto-Save" fragment is reclaimed into a modern React component using the data extracted via logic fragment discovery reclaiming:

tsx
import React, { useState, useEffect } from 'react';
import { useEligibilityLogic } from './hooks/useEligibilityLogic';

// Discovered Component: ClaimForm (Legacy: pnl_ClaimEntry)
export const ClaimForm: React.FC = () => {
  const [formData, setFormData] = useState({ age: 0, type: 'BASIC', history: false });
  const { isEligible, premiumAdjustment, errors } = useEligibilityLogic(formData.age, formData.type, formData.history);

  // Reclaimed Fragment: Auto-save logic discovered from legacy 'Timer1_Tick'
  useEffect(() => {
    const timer = setTimeout(() => {
      if (formData.age > 0) {
        console.log("Auto-saving draft with adjustment:", premiumAdjustment);
        // API.saveDraft(formData);
      }
    }, 3000);
    return () => clearTimeout(timer);
  }, [formData, premiumAdjustment]);

  return (
    <div className="p-6 border rounded-lg shadow-sm">
      <h2 className="text-xl font-bold mb-4">Claim Entry</h2>
      <input 
        type="number" 
        onChange={(e) => setFormData({...formData, age: parseInt(e.target.value)})}
        className={errors.length > 0 ? 'border-red-500' : ''}
      />
      {!isEligible && <p className="text-red-600">{errors[0]}</p>}
      <p>Current Multiplier: {premiumAdjustment}x</p>
    </div>
  );
};

The Strategic Advantage of Visual Reverse Engineering#

The $3.6 trillion technical debt problem isn't just about old syntax; it's about lost knowledge. When developers leave an enterprise, they take the "why" with them. The "what" remains in the code, but it's often indecipherable.

Logic fragment discovery reclaiming acts as a knowledge recovery tool. By recording the UI, you are capturing the only living documentation of the system. According to Replay's analysis, enterprises that use visual mining see a 70% average time savings compared to manual rewrites. This shifts the modernization timeline from 18 months down to just a few weeks of recording and refinement.

Building a Design System from Fragments#

One of the most powerful outcomes of using Replay is the automatic creation of a Library. As fragments are discovered, they are categorized into a Design System.

• •Buttons, Inputs, and Modals: Identified as UI components.
• •Validation Rules: Identified as logic fragments.
• •Data Fetching Patterns: Identified as service fragments.

This allows organizations to modernize without rewriting from scratch, as they can reuse these reclaimed fragments across multiple new applications, ensuring consistency between the old and new systems during the transition phase.

Overcoming the "Black Box" in Regulated Industries#

For Financial Services, Healthcare, and Government sectors, "guessing" how logic works is not an option. Compliance requires that the new system behaves exactly like the old one, or that every change is documented.

Logic fragment discovery reclaiming provides an audit trail. You have the video recording of the legacy system (the "source of truth"), the discovered fragment (the "analysis"), and the React code (the "implementation"). This "provenance of logic" is essential for SOC2 and HIPAA-ready environments. Replay is built for these environments, offering On-Premise availability to ensure that sensitive data never leaves the corporate network during the discovery phase.

Best Practices for Logic Fragment Discovery Reclaiming#

To maximize the efficiency of your modernization project, industry experts recommend the following workflow:

1. •Prioritize High-Value Workflows: Don't try to reclaim the whole app at once. Start with the workflows that have the highest user volume or the most frequent bugs.
2. •Use SMEs, Not Just Devs: Have the people who use the app every day do the recordings. They know the "hidden" features and edge cases that a developer might miss.
3. •Validate Fragments Early: Use Replay’s Blueprints to review the discovered logic before generating the final code. This ensures the AI has correctly interpreted the business rules.
4. •Integrate with a Design System: Ensure all reclaimed UI components are piped directly into your Centralized Design System.

Frequently Asked Questions#

What is logic fragment discovery reclaiming?#

It is the process of using visual reverse engineering and workflow mining to identify and extract business rules and UI logic that are buried within legacy software applications. This allows organizations to move logic from undocumented legacy code into modern, documented React components.

How does visual workflow mining differ from standard screen recording?#

Standard screen recording creates a video file. Visual workflow mining, used by platforms like Replay, captures the metadata, state changes, and component hierarchies behind the video. It uses AI to translate those visual actions into structured code and architectural blueprints.

Can Replay handle non-web legacy applications?#

Yes. Replay is designed to work with a variety of legacy environments, including desktop applications (VB6, Delphi, .NET) and older web technologies (Silverlight, Flash, ASP.NET). By analyzing the visual output and user interaction patterns, it can reclaim logic regardless of the original source language.

Is logic fragment discovery reclaiming secure for HIPAA or SOC2 environments?#

Yes, when using a platform like Replay that offers On-Premise deployments and SOC2 compliance. The discovery process can be performed entirely within your secure environment, ensuring that sensitive data used during the recording phase is never exposed to the public cloud.

How much time can I actually save using this method?#

On average, Replay users report a 70% reduction in modernization timelines. Specifically, the manual process of documenting and rebuilding a single complex screen typically takes 40 hours, whereas logic fragment discovery reclaiming with Replay reduces that to approximately 4 hours.

Reclaiming the Future of Your Application#

The path to a modern architecture doesn't have to be paved with failed rewrites and endless manual audits. By embracing logic fragment discovery reclaiming, you can turn your legacy "debt" into a documented, modular, and scalable asset.

Instead of spending 18 months trying to understand your past, you can spend a few weeks recording it and the rest of your time building the future. Replay provides the tools—Library, Flows, Blueprints, and the AI Automation Suite—to make this transition seamless.

Ready to modernize without rewriting? Book a pilot with Replay