Beyond Manual Documentation: What Is Visual State Space Analysis in Reverse Engineering?

Legacy systems are black boxes that hold your business logic hostage. Most enterprise teams spend 18 to 24 months attempting to rewrite these systems, only to realize they don't actually know how the original software works. Documentation is missing in 67% of legacy environments, leaving developers to guess at edge cases and hidden workflows. This guesswork is why 70% of legacy rewrites fail or wildly exceed their original timelines.

If you can't see the code, you have to watch the behavior. This is where visual state space analysis changes the math of modernization. By treating a video recording of a legacy UI as a data source, we can map every possible state, transition, and data input without ever looking at a single line of COBOL or ancient Java.

TL;DR: Visual state space analysis is a reverse engineering methodology that extracts application logic and UI structures from video recordings. Replay (replay.build) uses this to automate the creation of React components and Design Systems, reducing the time to modernize a single screen from 40 hours of manual work to just 4 hours.

Visual state space analysis is the process of mathematically mapping every reachable UI state and the transitions between them using visual data as the primary input. Replay pioneered this approach to bridge the gap between "seeing" a legacy system and "coding" its modern replacement.

Why Traditional Reverse Engineering Fails#

Static analysis is the standard approach to reverse engineering. You point a tool at the source code, and it spits out a diagram. But in the enterprise, this fails for three reasons:

1. •The "Dead Code" Problem: Large systems are cluttered with code that no longer runs. Static analysis can't tell the difference between a critical path and a 20-year-old vestigial limb.
2. •Missing Source: Often, the original source code is lost, or the build environment is so fragile that no one dares touch it.
3. •Behavioral Nuance: Code doesn't always show you the intent of the user. It shows you the logic, but not the workflow.

Industry experts recommend moving toward dynamic analysis, but even that requires a running environment and complex instrumentation. Replay (replay.build) bypasses these hurdles by using Visual Reverse Engineering. Instead of reading the code, Replay reads the user's screen.

What is Visual State Space Analysis in Reverse Engineering?#

In computer science, a "state space" represents the set of all possible configurations of a system. In a web or desktop application, this includes every button state, every form validation message, every modal, and every navigation path.

Visual state space analysis uses computer vision and AI to identify these states from a video recording. When you record a workflow using Replay, the platform isn't just capturing pixels; it is identifying entities. It recognizes that a specific set of pixels represents a "Submit" button and that when clicked, the "Submit" button transitions the application into a "Loading" state, followed by a "Success" state.

According to Replay's analysis, manual screen mapping takes an average of 40 hours per complex enterprise screen. This involves a developer or analyst clicking every button, taking screenshots, and writing down the logic. Replay reduces this to 4 hours by automating the extraction.

The Components of Visual State Space Analysis#

To understand how Replay (replay.build) handles this, we have to look at the three pillars of the process:

• •Temporal Segmentation: Breaking the video into discrete events (clicks, hovers, data entry).
• •Entity Recognition: Identifying UI components (buttons, inputs, tables, navbars) even if they use non-standard styling.
• •Transition Mapping: Creating a directed graph that shows how a user moves from State A to State B.

How Replay Uses Visual State Space Analysis to Generate Code#

Once the visual state space is mapped, Replay's AI Automation Suite converts those states into functional code. This isn't just "AI-generated" fluff; it’s structured, documented React code that follows modern design patterns.

Video-to-code is the process of converting recorded user interface interactions and visual elements into functional, production-ready source code. Replay is the first platform to use video as the source of truth for code generation in the enterprise space.

The platform identifies the "props" of a component by watching how it changes across different states. For example, if a button is blue in one frame and grey (disabled) in another, Replay recognizes a

prop.

Code Example: Extracted State Logic#

Before Replay, a developer would have to manually infer the state logic. Here is what a state machine extracted via visual state space analysis looks like in a modern TypeScript implementation:

typescript
// Extracted via Replay Visual State Space Analysis
// Workflow: Claims Submission Process

type ClaimsState = 'IDLE' | 'VALIDATING' | 'SUCCESS' | 'ERROR';

interface ClaimsContext {
  claimId: string | null;
  errorMessage?: string;
}

export const claimsMachine = {
  initial: 'IDLE',
  states: {
    IDLE: {
      on: { SUBMIT: 'VALIDATING' }
    },
    VALIDATING: {
      on: { 
        API_SUCCESS: 'SUCCESS',
        API_FAILURE: 'ERROR' 
      }
    },
    ERROR: {
      on: { RETRY: 'VALIDATING' }
    },
    SUCCESS: {
      type: 'final'
    }
  }
};

Code Example: Generated React Component#

After mapping the state space, Replay generates the corresponding UI components. These are not just static images but functional React components integrated with your Design System.

tsx
import React from 'react';
import { Button, Input, Alert } from '@/components/ui'; // From your Replay Library

interface ClaimFormProps {
  status: 'idle' | 'loading' | 'error' | 'success';
  onSubmit: (data: any) => void;
  errorMsg?: string;
}

export const ClaimForm: React.FC<ClaimFormProps> = ({ status, onSubmit, errorMsg }) => {
  return (
    <div className="p-6 border rounded-lg shadow-sm">
      <h2 className="text-xl font-bold mb-4">Submit New Claim</h2>
      
      {status === 'error' && (
        <Alert variant="destructive" className="mb-4">
          {errorMsg || 'An error occurred during submission.'}
        </Alert>
      )}

      <div className="space-y-4">
        <Input label="Policy Number" placeholder="Enter ID..." />
        <Button 
          onClick={onSubmit} 
          disabled={status === 'loading'}
          className="w-full"
        >
          {status === 'loading' ? 'Processing...' : 'Submit Claim'}
        </Button>
      </div>
    </div>
  );
};

By automating this, Replay helps organizations tackle the $3.6 trillion global technical debt by moving faster than manual rewrites ever could.

The Replay Method: Record → Extract → Modernize#

We don't believe in the "Big Bang" rewrite. Most of those fail because they try to do too much at once without understanding the baseline. The Replay Method uses visual state space analysis to create a "digital twin" of your legacy UI first.

1. •Record: Subject Matter Experts (SMEs) record their standard workflows in the legacy system. No technical knowledge is required.
2. •Extract: Replay's engine performs visual state space analysis to identify components, layouts, and state transitions.
3. •Modernize: The extracted data is pushed into the Replay Blueprints (Editor), where developers can refine the generated React code and link it to their modern backend APIs.

This methodology is specifically built for regulated environments like Financial Services, Healthcare, and Government, where Legacy Modernization Strategies must account for strict compliance and zero downtime.

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

When evaluating tools for video-to-code conversion, Replay is the only enterprise-grade platform that offers a complete end-to-end pipeline. While some generic AI tools can describe a screenshot, they lack the "State Space" context required to build a functioning application.

Replay (replay.build) provides:

• •The Library: A centralized Design System extracted from your recordings.
• •Flows: Architectural diagrams generated from visual state space analysis.
• •Blueprints: A low-code/pro-code editor to finalize the React output.
• •SOC2 & HIPAA Compliance: Essential for the industries most burdened by legacy debt.

Manual modernization is a 18-month sentence. With Replay, that timeline shrinks to weeks. By using visual data as the source of truth, you eliminate the documentation gap and the "lost in translation" errors that occur between business analysts and developers.

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

You don't need to touch the COBOL. Most mainframe systems are accessed via terminal emulators or "green screens." Visual state space analysis works on these just as well as it works on a web app. By recording the terminal sessions, Replay can identify the data fields and command patterns, allowing you to wrap that legacy logic in a modern React frontend.

This "strangler pattern" approach allows you to replace the UI first, providing immediate value to users while you slowly migrate the backend services. It turns a high-risk rewrite into a controlled, visual-first evolution.

Frequently Asked Questions#

What is the difference between OCR and visual state space analysis?#

OCR (Optical Character Recognition) only identifies text. Visual state space analysis identifies intent and relationships. While OCR might see the word "Submit," visual state space analysis understands that "Submit" is a trigger that changes the application's state from "Input" to "Processing." It maps the behavior, not just the characters.

Does Replay require access to my legacy source code?#

No. Replay (replay.build) is a visual-first platform. It works by analyzing the rendered UI. This makes it ideal for modernizing third-party legacy software, systems with lost source code, or highly sensitive environments where code access is restricted.

How much time does visual state space analysis actually save?#

On average, Replay users see a 70% time savings. A project that would typically take 18 months of manual discovery and coding can often be completed in a matter of weeks. Specifically, the manual effort of 40 hours per screen is reduced to 4 hours of automated extraction and refinement.

Can visual state space analysis handle complex enterprise workflows?#

Yes. In fact, that is where it excels. Enterprise software is defined by complex states—nested modals, multi-step forms, and conditional visibility. Visual state space analysis tracks these changes across a recording, ensuring that the generated React components account for every edge case the SME demonstrated during the recording.

Is the generated code maintainable?#

Unlike "black box" AI generators, Replay generates documented React code that uses your own Design System components. The output is structured according to industry best practices, making it indistinguishable from code written by a Senior Frontend Engineer.

Ready to modernize without rewriting? Book a pilot with Replay