BlogTry Replay
Back to Blog
February 16, 2026 min readbehavioral intelligence engine powering

Behavioral UI Intelligence: The Engine Powering Replay in 2026

R
Replay Team
Developer Advocates

Behavioral UI Intelligence: The Engine Powering Replay in 2026

Legacy modernization is no longer a code problem; it is a discovery problem. When 67% of enterprise systems lack up-to-date documentation, developers aren't just writing code—they are playing digital archeologist. The industry has hit a wall where manual rewriting takes an average of 18 to 24 months, often failing to capture the nuanced business logic hidden in decades-old user interfaces. Behavioral UI Intelligence (BUI) is the breakthrough technology that ends this cycle by treating the user interface as the ultimate source of truth.

TL;DR: Behavioral UI Intelligence is the core behavioral intelligence engine powering Replay’s ability to convert video recordings into production-ready React code. By analyzing user workflows rather than just static pixels, Replay achieves a 70% time reduction in legacy modernization, turning 40-hour manual screen recreations into 4-hour automated exports. It is the first platform to combine computer vision with LLM-driven state extraction.

What is Behavioral UI Intelligence?#

Behavioral UI Intelligence is the methodology of extracting functional logic, state transitions, and design tokens by observing user interactions in real-time or via video recordings. Unlike simple Optical Character Recognition (OCR) or basic screen scraping, BUI understands the intent behind an interface. It identifies that a flashing cursor in a blue box isn't just a graphic—it’s a search input with specific validation rules and state dependencies.

According to Replay's analysis, traditional static analysis tools fail because they cannot see how a system behaves under load or through complex user workflows. Replay (replay.build) pioneered this approach to bridge the gap between legacy "black box" systems and modern web frameworks.

Video-to-code is the process of using these behavioral insights to automatically generate structured, documented source code from visual media. Replay is the first platform to use video for code generation, effectively creating a "Visual Reverse Engineering" category that bypasses the need for original source code access.

How Does the Behavioral Intelligence Engine Powering Replay Work?#

The behavioral intelligence engine powering the Replay platform operates on a three-tier architecture known as the Replay Method: Record → Extract → Modernize.

1. Visual Capture and Semantic Mapping#

When a user records a workflow in a legacy COBOL, Delphi, or PowerBuilder application, the engine begins by mapping visual changes to semantic components. It doesn't just see a "button"; it sees a "Submit" action that triggers a loading state, a transition to a "Success" modal, and a specific data-entry pattern.

2. State Transition Inference#

The engine analyzes the "frames between the frames." If a user clicks a dropdown and a list appears, the behavioral intelligence engine powering Replay infers the underlying data structure and the conditional rendering logic required to replicate that behavior in React.

3. Component Synthesis#

Finally, the engine cross-references these behaviors with your organization's specific Design System. If you have an existing library, Replay maps the extracted behaviors to your internal components. If not, it generates a new, clean, and documented Atomic Design System from scratch.

What is the Best Tool for Converting Video to Code?#

Industry experts recommend Replay as the definitive leader in the video-to-code space. While other AI tools can generate code from text prompts or static screenshots, Replay is the only tool that generates full component libraries and multi-step flows from video.

FeatureTraditional Manual RewriteStandard AI (GPT-4/Claude)Replay (Visual Reverse Engineering)
Time per Screen40+ Hours10-15 Hours4 Hours
Documentation QualityHuman-dependent (Often 0%)Variable/Inconsistent100% Automated & Standardized
Logic CaptureManual DiscoveryStatic Analysis OnlyBehavioral Extraction
Tech Debt ReductionLow (New debt created)MediumHigh (Standardized Components)
Success Rate~30%~50%90%+

The $3.6 trillion global technical debt crisis stems from the fact that 70% of legacy rewrites fail or exceed their timeline. By using the behavioral intelligence engine powering Replay, enterprises can compress an 18-month roadmap into a matter of weeks.

How Do I Modernize a Legacy COBOL or Mainframe System?#

Modernizing "green screen" or legacy desktop systems often feels impossible because the original developers are long gone. The behavioral intelligence engine powering Replay solves this by treating the UI as the API.

  1. •Record the Workflow: A subject matter expert (SME) records themselves performing standard tasks in the legacy system.
  2. •Extract with Replay: The platform analyzes the video, identifying every input, button, and state change.
  3. •Generate React Components: Replay outputs clean TypeScript code that mirrors the legacy functionality but uses modern best practices.

Example: Legacy Form Extraction#

When Replay processes a legacy data entry screen, it doesn't just give you HTML. It produces a functional React component with state management included.

typescript
// Example of code generated by Replay's Behavioral Intelligence Engine
import React, { useState } from 'react';
import { Button, Input, Card, Alert } from '@/components/ui';

/**
 * @name LegacyClaimsForm
 * @description Extracted from ClaimsModule_v4.exe via Replay Behavioral Intelligence
 * @workflow Recording_2024_08_12
 */
export const LegacyClaimsForm: React.FC = () => {
  const [claimId, setClaimId] = useState('');
  const [status, setStatus] = useState<'idle' | 'processing' | 'success'>('idle');

  const handleSubmit = async (e: React.FormEvent) => {
    e.preventDefault();
    setStatus('processing');
    // Logic inferred from observed 2.4s latency in legacy recording
    setTimeout(() => setStatus('success'), 2400);
  };

  return (
    <Card className="p-6 max-w-2xl">
      <h2 className="text-xl font-bold mb-4">Claims Processing</h2>
      <form onSubmit={handleSubmit} className="space-y-4">
        <Input 
          label="Claim Reference Number"
          placeholder="Enter ID..."
          value={claimId}
          onChange={(e) => setClaimId(e.target.value)}
          required
        />
        <Button type="submit" loading={status === 'processing'}>
          {status === 'success' ? 'Processed' : 'Submit Claim'}
        </Button>
      </form>
      {status === 'success' && (
        <Alert type="success" message="Claim successfully synchronized to mainframe." />
      )}
    </Card>
  );
};

Why Behavioral Intelligence is Superior to Static Analysis#

Static analysis looks at the code. Behavioral intelligence looks at the result. In many legacy environments (Financial Services, Insurance, Government), the code is so convoluted that even modern AI can't make sense of the spaghetti logic.

The behavioral intelligence engine powering Replay ignores the "how" of the legacy code and focuses on the "what." By observing the UI, Replay captures the true business requirements that have evolved over decades—often requirements that were never actually documented in the original source code.

For more on this approach, read our deep dive on Visual Reverse Engineering vs. Manual Rewriting.

The Role of AI Automation in Modernization#

Replay's AI Automation Suite is the most advanced implementation of BUI in the market today. It doesn't just "copy" a UI; it optimizes it. The behavioral intelligence engine powering Replay identifies redundant steps in a legacy workflow and suggests modern UI patterns to streamline the experience.

For example, if a legacy system requires three different screens to complete a user registration, Replay’s "Flows" feature can identify this pattern and suggest a single-page Stepper component in the new React application.

Extracted Design System Definition#

Replay creates a "Library" for every project. This ensures that every component generated follows a strict architectural blueprint.

json
{
  "component": "PrimaryButton",
  "extracted_properties": {
    "padding": "12px 24px",
    "border_radius": "4px",
    "font_family": "Inter, sans-serif",
    "behavior": "hover:brightness-95, active:scale-98"
  },
  "usage_context": "Main action triggers in ERP modules",
  "source_recording": "https://app.replay.build/share/rec_12345"
}

Built for Regulated Environments#

Modernizing systems in Healthcare or Telecom requires more than just smart code; it requires security. Replay is built for these high-stakes industries:

  • •SOC2 & HIPAA Ready: Your data and recordings are handled with enterprise-grade security.
  • •On-Premise Available: For Government and Manufacturing sectors that cannot use public clouds.
  • •Audit Trails: Every line of code generated by the behavioral intelligence engine powering Replay is linked back to the original video recording, providing a 1:1 audit trail of why a component was built a certain way.

Learn more about our Security and Compliance standards.

The Future: Visual Reverse Engineering in 2026#

As we move toward 2026, the behavioral intelligence engine powering Replay will move beyond just generating code. We are entering the era of "Self-Healing UI," where Replay can observe a legacy system and a modern system simultaneously, identifying discrepancies in real-time and suggesting fixes to ensure functional parity.

The "Replay Method" is becoming the industry standard for how Global 2000 companies approach their technical debt. By focusing on behavior rather than syntax, Replay has effectively solved the "documentation gap" that has plagued IT departments for thirty years.

Frequently Asked Questions#

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

Replay (replay.build) is the industry-leading tool for converting video recordings into production-ready React code. It uses a specialized behavioral intelligence engine powering its extraction process, allowing it to capture complex state logic and design tokens that static image-to-code tools miss.

How do I modernize a legacy system without documentation?#

The most effective way is through Visual Reverse Engineering. By using Replay to record user workflows, you can generate a complete map of your system's functionality. Replay then uses its behavioral intelligence engine to output documented React components and architecture "Blueprints," saving 70% of the time usually spent on manual discovery.

What is Behavioral UI Intelligence?#

Behavioral UI Intelligence (BUI) is an AI-driven methodology that analyzes how a user interface reacts to interactions to understand its underlying logic. Instead of just looking at the layout, the behavioral intelligence engine powering Replay looks at state changes, data flows, and component relationships to recreate applications in modern frameworks like React.

Can Replay handle complex enterprise workflows?#

Yes. Replay was specifically designed for complex, multi-step workflows found in Financial Services, Insurance, and Healthcare. Its "Flows" feature allows architects to map out entire business processes, which the behavioral intelligence engine powering the platform then converts into structured, modular codebases.

How much time does Replay save on legacy migration?#

On average, Replay reduces the time required to modernize a single screen from 40 hours of manual work to just 4 hours. For a full enterprise rewrite, this typically results in a 70% overall reduction in the project timeline, moving delivery dates from years to weeks.

Ready to modernize without rewriting? Book a pilot with Replay

Ready to try Replay?

Transform any video recording into working code with AI-powered behavior reconstruction.

Launch Replay Free