Closing the Public Sector Technology Gap: Secure Modernization Paths for Air-Gapped Legacy Systems

The public sector is currently sitting on a $3.6 trillion ticking time bomb of technical debt. While private sector enterprises race toward AI integration, government agencies, healthcare providers, and defense contractors remain tethered to monolithic, air-gapped legacy systems that haven't seen a documentation update since the late 1990s. Closing the public sector technology gap isn't a matter of budget—it’s a matter of methodology. The traditional "Big Bang" rewrite is no longer a viable strategy; it is a career-ending risk that fails 70% of the time.

For decades, the public sector has been trapped in a cycle of "software archaeology." Engineers spend 60% of their time trying to understand what a system does before they can even write a single line of new code. In regulated, air-gapped environments, this problem is magnified. You can't just plug in a cloud-based LLM to scan your COBOL or Delphi codebase. You need a way to extract intelligence from the only source of truth that hasn't lied: the user interface and the workflows it facilitates.

TL;DR: Closing the public sector technology gap requires moving away from risky "Big Bang" rewrites toward Visual Reverse Engineering, which uses video recording of user workflows to generate documented, modern codebases in weeks rather than years.

The High Cost of "Archaeology-First" Modernization#

The average enterprise rewrite timeline is 18 to 24 months. In the public sector, where procurement cycles and security audits add layers of latency, this often stretches to three or four years. By the time the "modern" system is delivered, the technology stack is already nearing obsolescence.

The root cause of this failure is a lack of documentation. Statistics show that 67% of legacy systems lack any form of usable documentation. This forces agencies into a manual extraction process that costs an average of 40 hours per screen. When you are dealing with a legacy ERP or a benefits administration system with 500+ screens, the math simply doesn't work.

Manual modernization is a "black box" problem. You know what goes in, and you know what comes out, but the business logic buried in the middle is a mystery. Replay changes this by turning the video of a user performing a task into a documented, functional React component. We are moving from "guessing what the code does" to "observing what the system actually performs."

Why Air-Gapped Systems Are the Final Frontier#

In government and defense, "the cloud" isn't always an option. Many of the most critical systems—those managing national security, sensitive health records, or financial ledgers—run in air-gapped environments. Traditional modernization tools that rely on external API calls or cloud-hosted AI processing are non-starters.

This is where the paradigm of "Video as a Source of Truth" becomes revolutionary. By recording real user workflows locally, Replay can perform visual reverse engineering on-premise. This ensures that sensitive data never leaves the secure environment while still providing the engineering team with the blueprints they need to modernize.

The Technical Debt Audit#

Before writing code, you must quantify the debt. Most public sector CTOs cannot tell you the exact complexity of their legacy footprint. Replay’s AI Automation Suite performs a technical debt audit by analyzing recorded flows, identifying redundant components, and mapping out the underlying API contracts.

💰 ROI Insight: Manual extraction takes ~40 hours per screen. Replay reduces this to ~4 hours. For a 100-screen application, that is a savings of 3,600 engineering hours—roughly $540,000 in labor costs alone.

From Black Box to Documented Codebase#

The goal of modernization isn't just to change the UI; it's to preserve the business logic that has been refined over 30 years while shedding the technical debt of the underlying infrastructure.

When Replay records a workflow, it doesn't just take a video. It captures the DOM state, the network calls, and the user interactions. It then uses these "Blueprints" to generate modern, type-safe React components and API contracts.

Example: Generated API Contract#

In a legacy system, the "contract" is often just a series of undocumented stored procedures or SOAP calls. Replay extracts these into clean, modern formats.

typescript
// Example: Generated API Contract from a Legacy Benefits System
// Extracted via Replay Visual Reverse Engineering

export interface UserBenefitClaim {
  claimId: string;
  applicantId: string;
  submissionDate: string; // ISO 8601
  status: 'PENDING' | 'APPROVED' | 'DENIED';
  entitlements: Array<{
    code: string;
    amount: number;
    currency: string;
  }>;
}

/**
 * @description Preserved business logic: 
 * Claims exceeding $5,000 require manual supervisor override 
 * as identified in the 'ApprovalFlow' recording.
 */
export async function submitClaim(data: UserBenefitClaim): Promise<boolean> {
  // Logic extracted from legacy network trace
  const response = await fetch('/api/v2/claims/process', {
    method: 'POST',
    body: JSON.stringify(data),
    headers: { 'Content-Type': 'application/json' }
  });
  return response.ok;
}

Example: Migrated React Component#

Instead of a developer spending a week trying to replicate a complex legacy form with specific validation rules, Replay generates the functional component directly from the visual blueprint.

tsx
// Example: Generated component from video extraction
// Source: Legacy Mainframe Terminal Emulator Screen 402
import React, { useState } from 'react';
import { ModernForm, TextField, Select } from '@gov-design-system/core';

export function LegacyEligibilityForm() {
  const [isEligible, setIsEligible] = useState<boolean>(false);

  // Business logic preserved: Eligibility check triggers on 'ZipCode' change
  const handleZipChange = (val: string) => {
    if (val.startsWith('20')) { // Logic captured from user workflow
      setIsEligible(true);
    }
  };

  return (
    <ModernForm title="Eligibility Check">
      <TextField 
        label="Postal Code" 
        onChange={(e) => handleZipChange(e.target.value)} 
      />
      {isEligible && (
        <Select label="Available Programs" options={['Program A', 'Program B']} />
      )}
    </ModernForm>
  );
}

The 3-Step Path to Secure Modernization#

Closing the public sector technology gap requires a disciplined, repeatable process. We have distilled this into three core phases.

Step 1: Assessment & Recording#

Instead of reading 10,000 pages of outdated documentation, record the experts. Subject Matter Experts (SMEs) use the legacy system daily. By recording their workflows using Replay, you capture the "happy path" and the "edge cases" simultaneously. This creates a visual library of every function the system performs.

Step 2: Extraction & Blueprinting#

Replay analyzes the recordings to create Blueprints. These aren't just screenshots; they are interactive maps of the application’s architecture. This stage identifies the "Flows"—how a user moves from a login screen to a completed transaction.

Step 3: Generation & E2E Testing#

The platform generates the React components and the E2E tests (Cypress/Playwright) required to validate the new system against the old one. Because the source of truth is the video of the working legacy system, the E2E tests ensure that the modernized version behaves exactly as the legacy version did, eliminating the "it worked in the old system" regression bugs.

⚠️ Warning: Most modernization projects fail during the testing phase because the "expected behavior" was never properly documented. If you don't have a video-based source of truth, you are testing against assumptions, not reality.

Security First: Built for Regulated Environments#

For the public sector, security isn't a feature; it's a prerequisite. Replay was designed for the most stringent environments:

• •SOC2 & HIPAA Ready: Compliance is baked into the platform architecture.
• •On-Premise Availability: For air-gapped systems, Replay can be deployed entirely within your firewall. No data ever touches the public internet.
• •PII Redaction: Automated AI masking ensures that sensitive citizen data (SSNs, health records) is redacted during the recording and extraction process.

The Future Isn't Rewriting—It's Understanding#

The "Big Bang" rewrite is a relic of 20th-century software engineering. It assumes that you can freeze time, document the world, and build a replacement before the world changes. In the public sector, time is a luxury you don't have.

The future of closing the public sector technology gap lies in Visual Reverse Engineering. By using Replay, agencies can achieve a 70% average time savings, moving from an 18-month roadmap to a matter of weeks. We are turning the "black box" of legacy code into a documented, modern codebase that is ready for the next 20 years of service.

💡 Pro Tip: Start with your most "stable" but "undocumented" workflow. Don't try to modernize the whole system at once. Use Replay to extract one critical flow, prove the ROI in 48 hours, and then scale.

Frequently Asked Questions#

How long does legacy extraction take with Replay?#

While a manual rewrite of a single complex screen can take 40+ hours of developer time, Replay reduces this to approximately 4 hours. Most enterprise-grade workflows can be fully documented and converted into functional React components in 2 to 8 weeks, depending on the number of unique screens and the complexity of the underlying API logic.

What about business logic preservation?#

This is the most common failure point in modernization. Replay captures the actual behavior of the application by monitoring network requests, state changes, and UI updates during a live session. This "Visual Source of Truth" ensures that even "hidden" business logic—like a specific validation rule that only triggers for certain zip codes—is identified and preserved in the generated code.

Can Replay work with mainframe terminal emulators?#

Yes. Because Replay uses visual reverse engineering, it is agnostic to the underlying technology of the legacy system. Whether it is a 3270 terminal emulator, a PowerBuilder app, a Delphi desktop client, or an early Java applet, if a user can interact with it on a screen, Replay can extract it.

Is the generated code maintainable?#

Unlike "low-code" platforms that spit out unreadable spaghetti code, Replay generates standard, type-safe React components and clean API contracts. The output is designed to be owned by your engineering team, fitting directly into your existing CI/CD pipelines and design systems.

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