Closing the Documentation Gap: Why Manual Archaeology is Killing Medical Device Modernization

The average enterprise rewrite takes 18 months, and 70% of them either fail or significantly exceed their original timeline. In the regulated world of medical device software, these statistics aren't just business risks—they are regulatory liabilities. When your legacy system is a "black box" lacking documentation, you aren't just dealing with technical debt; you are dealing with a compliance time bomb.

TL;DR: Closing the documentation gap in medical device software requires shifting from manual code archaeology to visual reverse engineering, reducing documentation time from 40 hours per screen to just 4 hours using Replay.

The Compliance Crisis: When Documentation Doesn't Match Reality#

In MedTech, the delta between what the software does and what the documentation says it does is the "Documentation Gap." For systems governed by FDA 21 CFR Part 11 or ISO 13485, this gap is an existential threat. Most legacy systems—some running for 15+ years—suffer from "Documentation Drift."

The current state of the industry is grim: 67% of legacy systems lack accurate documentation. When an auditor asks for the design history file (DHF) or the software requirement specifications (SRS) for a system that has been patched a thousand times by engineers who have since left the company, most organizations panic. They resort to "Code Archaeology"—paying $250/hour consultants to sit in a room and guess what a 5,000-line COBOL or Delphi file is doing.

This approach is fundamentally broken. It is slow, prone to human error, and creates a secondary documentation gap the moment the "new" documentation is finished.

The Failure of the "Big Bang" Rewrite#

The gut reaction for many CTOs in healthcare is to "burn it down and start over." They believe that starting from scratch is the only way to ensure a clean, documented codebase. The data suggests otherwise.

Global technical debt has ballooned to $3.6 trillion because companies keep trying to outrun their legacy instead of understanding it. In a regulated environment, a "Big Bang" rewrite means re-verifying and re-validating every single requirement from scratch.

⚠️ Warning: Attempting a rewrite without first closing the documentation gap is the leading cause of "feature parity" failure, where the new system fails to replicate critical, undocumented edge cases from the legacy system.

Closing the Documentation Gap with Visual Reverse Engineering#

The future of modernization isn't rewriting; it’s understanding. Replay introduces a paradigm shift: Video as the source of truth.

Instead of reading through millions of lines of spaghetti code, Replay records real user workflows. It captures the state, the data transitions, and the UI components in real-time. It then uses AI to reverse engineer those recordings into documented React components and API contracts.

From Black Box to Documented Codebase#

When you use Replay, you are effectively "recording" the legacy system's institutional knowledge. This isn't just a screen recording; it's a deep-packet inspection of the application's behavior.

• •Library: Automatically generates a Design System from your legacy UI.
• •Flows: Maps the architectural journey of a user through the system.
• •Blueprints: Provides a visual editor to refine the extracted logic.
• •AI Automation: Generates the technical documentation and E2E tests required for regulatory submission.

💰 ROI Insight: Manual documentation takes an average of 40 hours per screen. Replay reduces this to 4 hours. For a 50-screen medical portal, that is a saving of 1,800 engineering hours.

Technical Implementation: Extracting Logic from the Void#

How does this look in practice? Consider a legacy medical billing form. It likely has complex, undocumented validation logic for ICD-10 codes. In a manual rewrite, an engineer might miss the specific regex or the conditional logic that handles edge cases for pediatric patients.

With Replay, the recording captures the exact state changes. The platform then generates a modern, documented React component that preserves that business logic.

typescript
// Example: Generated component from Replay visual extraction
// Logic preserved from legacy "BillingModule_v2_final_DEPRECATED.vb"
import React, { useState, useEffect } from 'react';
import { validateICD10, calculateInsuranceCoPay } from './legacy-logic-bridge';

export function PatientBillingForm({ patientId, providerId }) {
  const [billingData, setBillingData] = useState({
    icdCode: '',
    amount: 0,
    isPediatric: false
  });

  // Replay extracted this specific conditional logic from user workflow recordings
  const handleSubmit = async (e: React.FormEvent) => {
    e.preventDefault();
    if (billingData.isPediatric && !billingData.icdCode.startsWith('P')) {
      console.error("Validation Error: Pediatric codes must start with P");
      return;
    }
    // Proceed with API call based on extracted contract
    await submitBilling(billingData);
  };

  return (
    <div className="modern-form-container">
      {/* UI components mapped to your new Design System */}
      <Input 
        label="ICD-10 Code" 
        value={billingData.icdCode} 
        onChange={(val) => setBillingData({...billingData, icdCode: val})} 
      />
      <Button onClick={handleSubmit}>Submit Claim</Button>
    </div>
  );
}

Automating API Contracts#

One of the biggest hurdles in closing the documentation gap is the backend. Legacy systems often have "undocumented APIs" or direct database connections that no one understands. Replay observes the network traffic during the recording and generates OpenAPI (Swagger) specifications automatically.

yaml
# Generated by Replay AI Automation Suite
openapi: 3.0.0
info:
  title: Legacy Medical Records API
  version: 1.0.4
paths:
  /api/v1/patient/records:
    get:
      summary: Extracted from "View History" workflow
      parameters:
        - name: patient_id
          in: query
          required: true
          schema:
            type: string
      responses:
        '200':
          description: OK
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/PatientRecord'

The 3-Step Process to Modernize Regulated Software#

Step 1: Visual Recording & Assessment#

Instead of a 6-month discovery phase, you spend two weeks recording every critical path in the legacy application. This includes the "happy path" and the "exception paths" (e.g., what happens when a user enters an invalid SSN?). Replay captures these flows, creating an immediate visual inventory of the system.

Step 2: Extraction & Componentization#

Replay’s AI Suite parses the recordings. It identifies patterns in the UI to build a Library (Design System) and extracts the underlying business logic. This is where you move from "understanding" to "generating." You aren't writing code from scratch; you are refining the code Replay has extracted from the source of truth.

Step 3: Automated Documentation & Testing#

For medical device software, the "Code" is only half the battle. You need the "Proof." Replay generates:

• •Technical Debt Audits: Identifying exactly where the legacy logic is brittle.
• •E2E Tests: Automatically generating Playwright or Cypress tests that mimic the recorded user behavior.
• •Traceability Matrix: Linking the new React components back to the original legacy workflows.

💡 Pro Tip: Use Replay’s "Blueprints" to visualize the state machine of your legacy application. This is often the first time stakeholders will see the actual complexity of their business logic in a readable format.

Why "Modernize Without Rewriting" is the Only Viable Path#

The term "rewrite" should be a red flag in any enterprise architecture meeting. A rewrite implies that the existing system has zero value. But for a healthcare company, the legacy system contains decades of "bug fixes" that are actually undocumented business requirements.

When you "Modernize without rewriting" using Replay, you are performing a surgical extraction. You keep the logic that works, document the logic that was hidden, and replace the delivery mechanism (the UI/UX) with modern React components.

• •Preserve Institutional Knowledge: Don't lose the edge cases that developers fixed in 2008.
• •Reduce Validation Burden: Since you are extracting logic rather than inventing it, the delta for re-validation is significantly smaller.
• •Eliminate Archaeology: Stop paying senior architects to read old logs. Let Replay document the system while your team builds new features.

Built for Regulated Environments#

We understand that in Healthcare and Financial Services, "Cloud-only" is often a non-starter. Replay is built with a security-first mindset:

• •SOC2 & HIPAA Ready: Data handling that meets the highest standards of privacy.
• •On-Premise Availability: Keep your source code and recordings within your own firewall.
• •Audit Trails: Every extraction and change is logged, providing the transparency required for regulatory bodies.

Frequently Asked Questions#

How long does legacy extraction take?#

While a manual audit can take months, Replay typically allows teams to move from recording to a documented React component in a matter of days. Most enterprise clients see a full "screen-to-code" extraction in 4 hours per screen, compared to the industry average of 40 hours.

What about business logic preservation?#

This is Replay’s core strength. Because we record the actual state transitions and data flows of the running application, we capture the "as-is" logic, not the "as-intended" logic found in outdated docs. Our AI Suite then formats this logic into readable, maintainable TypeScript.

Does Replay replace my engineering team?#

No. Replay is a force multiplier for your Enterprise Architects and Senior Developers. It removes the "grunt work" of manual documentation and reverse engineering, allowing your team to focus on high-value architectural decisions and new feature development.

Can Replay handle mainframe or "green screen" applications?#

Yes. If a user can interact with it via a browser or a terminal emulator, Replay can record the workflow and begin the extraction process. We have helped organizations move from 30-year-old terminal systems to modern web architectures in weeks.

---

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