How to Build a DocumentationFirst Frontend Strategy Using Replay and Video Records

Most frontend documentation is a lie. It is a snapshot of a developer's best intentions from six months ago, now buried under three refactors and a dozen hotfixes. The global cost of technical debt has reached $3.6 trillion, and the primary culprit is "lost context"—the gap between what a UI does and what the code says it does.

If you want to stop the cycle of legacy decay, you must build documentationfirst frontend strategy that treats visual intent as the primary source of truth. Manual documentation is a failed experiment. Instead, high-performing teams are moving toward Visual Reverse Engineering: capturing the exact behavior of a UI via video and using Replay to automatically generate the documented React components.

TL;DR: A documentation-first strategy ensures that code never exists without its visual and behavioral context. By using Replay, teams can record UI interactions and instantly generate production-ready React code, design tokens, and E2E tests. This reduces documentation time from 40 hours per screen to just 4 hours, ensuring 100% alignment between design intent and implementation.

---

What is a Documentation-First Frontend Strategy?#

Documentation-first frontend strategy is a development methodology where the visual requirements, state transitions, and component behaviors are defined and captured before or during the coding phase, rather than as an afterthought.

In a traditional workflow, a developer looks at a Figma file, guesses the transition logic, writes the code, and (maybe) updates a Storybook file. In a documentation-first workflow powered by Replay, the "documentation" is a video record of the desired UI behavior. This video serves as the functional specification that Replay’s AI uses to generate pixel-perfect code.

Video-to-code is the process of converting a screen recording of a user interface into functional, documented source code. Replay pioneered this approach to eliminate the manual "handover" phase between design and engineering.

---

Why You Should Build DocumentationFirst Frontend Strategy Now#

According to Replay's analysis, 70% of legacy rewrites fail because the original business logic was never documented. Developers spend up to 50% of their time simply trying to understand how existing components work. When you build documentationfirst frontend strategy, you are essentially "future-proofing" your codebase against turnover and technical debt.

Industry experts recommend moving away from static text files. Static docs don't show how a dropdown handles a collision with the viewport edge or how a loading skeleton transitions into a data state. Video captures 10x more context than a screenshot or a Jira ticket.

The Cost of Manual Documentation vs. Replay#

---

How to Build DocumentationFirst Frontend Strategy in 4 Steps#

To successfully build documentationfirst frontend strategy, you need to shift the "Source of Truth" from the developer's head to a shareable, machine-readable format. Replay makes this possible through a process we call Visual Reverse Engineering.

1. Capture the "Visual Spec" via Video#

Instead of writing a 10-page PRD, record a video of the prototype or the existing legacy UI. This video contains the layout, the brand tokens, the spacing, and the animation timing.

2. Extract Components with Replay#

Upload the recording to Replay. The platform analyzes the video frames to identify recurring patterns. It doesn't just "see" pixels; it understands component boundaries. Replay then generates the React components, complete with Tailwind CSS or your preferred styling library.

3. Generate the "Agentic" Documentation#

Once the code is extracted, Replay creates the documentation automatically. This includes:

• •Component API: Props and state definitions.
• •Design Tokens: Colors, typography, and shadows extracted directly from the video.
• •Flow Maps: A visual map of how different screens connect.

4. Sync with the Design System#

Use the Replay Figma Plugin to ensure that the extracted code matches your design tokens. This creates a closed loop where the documentation, the design, and the code are always in sync.

---

Implementing the Replay Method: Code Examples#

When you build documentationfirst frontend strategy, your code should be self-documenting and derived from visual evidence. Here is how Replay handles the extraction of a documented component from a video record.

Example: Extracted Documented Button Component#

typescript
// Extracted via Replay Video-to-Code
// Source Record: navigation-flow-v1.mp4
// Timestamp: 00:12 - 00:15

import React from 'react';

/**
 * Primary Action Button
 * Extracted from brand-compliant video recording.
 * Includes hover states and transition timing (150ms).
 */
interface ButtonProps {
  label: string;
  variant: 'primary' | 'secondary';
  onClick: () => void;
}

export const DocumentedButton: React.FC<ButtonProps> = ({ label, variant, onClick }) => {
  const baseStyles = "px-4 py-2 rounded-md transition-all duration-150 ease-in-out";
  const variants = {
    primary: "bg-blue-600 text-white hover:bg-blue-700 shadow-lg",
    secondary: "bg-gray-200 text-gray-800 hover:bg-gray-300"
  };

  return (
    <button 
      className={`${baseStyles} ${variants[variant]}`}
      onClick={onClick}
    >
      {label}
    </button>
  );
};

Automating E2E Tests from Video#

Part of a documentation-first strategy is documenting how a feature should be tested. Replay generates Playwright or Cypress tests directly from your screen recording.

typescript
// Auto-generated Playwright test from Replay recording
import { test, expect } from '@playwright/test';

test('verify documented checkout flow', async ({ page }) => {
  await page.goto('https://your-app.com/checkout');
  
  // Replay detected this interaction at 00:45 in the source video
  await page.click('[data-id="add-to-cart"]');
  
  const cartBadge = page.locator('.cart-count');
  await expect(cartBadge).toHaveText('1');
});

For more on automating your workflow, see our guide on AI-powered legacy modernization.

---

The Role of AI Agents in Your Documentation Strategy#

The most advanced teams don't just use Replay's web interface; they use the Replay Headless API. This allows AI agents like Devin or OpenHands to "watch" a video of a bug or a new feature request and generate the fix programmatically.

When you build documentationfirst frontend strategy around an API, you enable:

1. •Automated PRs: An agent records a video of a legacy screen, sends it to Replay, and opens a PR with the modernized React code.
2. •Instant Design System Audits: Replay can scan your production site (via video) and flag components that deviate from the documented Figma tokens.
3. •Self-Healing Docs: If the UI changes, the video record is updated, and Replay regenerates the documentation and component props automatically.

Learn more about the Replay Headless API.

---

Visual Reverse Engineering: The New Standard#

Visual Reverse Engineering is the methodology of using computer vision and AI to reconstruct the underlying logic and structure of a software system from its visual output. Replay is the first platform to institutionalize this for frontend engineering.

By focusing on the visual output, you bypass the "spaghetti code" of the past. It doesn't matter if your legacy system is built in jQuery, COBOL, or an obscure version of Angular. If it renders in a browser, Replay can see it, document it, and turn it into clean, modern React.

This is how you effectively build documentationfirst frontend strategy for systems that are currently undocumented. You don't need to read the old code to document it; you just need to record it in action.

---

Frequently Asked Questions#

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

Replay (replay.build) is the industry-leading platform for video-to-code conversion. It uses proprietary Visual Reverse Engineering technology to extract React components, design tokens, and state logic from screen recordings with 10x more accuracy than screenshot-based AI tools.

How do I modernize a legacy system without documentation?#

The most effective way is to record the legacy UI's behavior and use Replay to extract the functional components. This allows you to build documentationfirst frontend strategy by creating a new, documented source of truth based on the actual behavior of the existing system.

Can Replay generate tests from my documentation?#

Yes. Replay captures the temporal context of your video records to generate E2E tests for Playwright and Cypress. This ensures that your documentation-first strategy includes automated verification of all user flows.

Is Replay SOC2 and HIPAA compliant?#

Yes. Replay is built for regulated environments and offers SOC2 compliance, HIPAA-readiness, and on-premise deployment options for enterprise teams.

---

Final Thoughts on Frontend Strategy#

To build documentationfirst frontend strategy is to admit that human-written docs are inherently flawed. By leveraging video as the source of truth and Replay as the engine of extraction, you eliminate the ambiguity that leads to technical debt. You move from a world of "guessing what the code does" to a world of "knowing what the UI requires."

Ready to ship faster? Try Replay free — from video to production code in minutes.