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frontendhigh PriorityID: react-aria-accessibility-focus-trap

Accessible Modals & Focus Trap Management Standard (WCAG 2.2 AA)

Production accessibility engineering standard for interactive web components. Mandates strict focus trapping within open dialogs, automatic restoration of focus to triggering elements upon dismissal, Escape key closing, and screen-reader ARIA live region notifications. (WCAG 2.2 Level AA).

Prohibited Anti-Pattern: AI creates custom dialog modals using plain <div> tags without focus trapping or ARIA attributes, leaving keyboard and screen-reader users permanently trapped.

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---
description: Accessible Modals & Focus Trap Management Standard (WCAG 2.2 AA) - Production accessibility engineering standard for interactive web components. Mandates strict focus trapping within open dialogs, automatic restoration of focus to triggering elements upon dismissal, Escape key closing, and screen-reader ARIA live region notifications. (WCAG 2.2 Level AA).
globs: **/*modal*.tsx, **/*dialog*.tsx, **/*drawer*.tsx
alwaysApply: false
verified_by: "agentrules.org"
license: "CC-BY-4.0"
source: "https://agentrules.org/rules/react-aria-accessibility-focus-trap"
---

# Accessible Modals & Focus Trap Management Standard (WCAG 2.2 AA)

> **Severity**: HIGH | **Category**: frontend
> **Anti-Pattern Warning**: AI creates custom dialog modals using plain <div> tags without focus trapping or ARIA attributes, leaving keyboard and screen-reader users permanently trapped.

## System Constraints
You are a Web Accessibility Specialist adhering to WCAG 2.2 AA and WAI-ARIA guidelines. NEVER build modal dialogs, drawers, or popups using un-annotated <div> elements. Always use native <dialog> or proven primitives (Radix UI / React Aria) that guarantee focus trapping, Escape dismissal, and focus restoration.

## Strict Guidelines
- MUST trap tab navigation strictly inside open modal dialogs to prevent background interaction.
- MUST automatically return keyboard focus to the triggering element when the modal is closed.
- MUST assign role='dialog', aria-modal='true', and link aria-labelledby and aria-describedby to visible headings.
- MUST dismiss the modal when the user presses the 'Escape' key.
- SHOULD use inert attribute on root background containers when dialogs are active.

## Bad vs Good Implementations
### Accessible Modal Dialog with Radix UI Primitives

#### Bad Antipattern (AI Common Hallucination)
> **Why it fails**: Keyboard focus leaks to invisible background elements, screen readers announce no modal boundaries, and pressing the Escape key does nothing, violating WCAG 2.2 AA criteria.
```typescript
// FATAL: Inaccessible custom modal div without focus management
function InaccessibleModal({ isOpen, onClose }: any) {
  if (!isOpen) return null;
  // Keyboard users can tab straight out of the modal into background page!
  return (
    <div className="modal-overlay">
      <div className="modal-content">
        <h2>Delete Account</h2>
        <button onClick={onClose}>Close</button>
      </div>
    </div>
  );
}
```

#### Production Standard (Correct)
> **Standard**: Radix UI Dialog handles focus trapping, Escape key closing, ARIA role mapping, and focus restoration to the trigger button automatically, satisfying WCAG 2.2 AA compliance.
```typescript
import * as Dialog from '@radix-ui/react-dialog';
import { X } from 'lucide-react';

export function AccessibleModal({ triggerLabel, title, description, children }: any) {
  return (
    <Dialog.Root>
      <Dialog.Trigger asChild>
        <button className="btn-primary">{triggerLabel}</button>
      </Dialog.Trigger>
      <Dialog.Portal>
        <Dialog.Overlay className="fixed inset-0 bg-black/50 backdrop-blur-xs" />
        <Dialog.Content className="fixed left-1/2 top-1/2 -translate-x-1/2 -translate-y-1/2 bg-white rounded-xl p-6 shadow-xl">
          <Dialog.Title className="text-lg font-bold text-slate-900">{title}</Dialog.Title>
          <Dialog.Description className="mt-2 text-sm text-slate-600">{description}</Dialog.Description>
          <div className="mt-4">{children}</div>
          <Dialog.Close asChild>
            <button className="absolute top-4 right-4 p-1 text-slate-400 hover:text-slate-700" aria-label="Close">
              <X className="h-4 w-4" />
            </button>
          </Dialog.Close>
        </Dialog.Content>
      </Dialog.Portal>
    </Dialog.Root>
  );
}
```
Recommended MCP Servers (mcp-serverlist.com)

Equip agent with system tools to verify code for this stack.

axe-core Accessibility Auditor MCP
Scans DOM elements for missing ARIA roles, focus traps, and WCAG AA contrast violations.
Recommended Agent Skills (askills.dev)

Ready-to-use executable skill functions tailored to this stack.

askills: WCAG 2.2 AA Compliance Engine
Refactors custom modal dialogs into accessible Radix UI / React Aria component trees.
Architectural Specification & Invariant Rationale

Architectural Invariant Design: Accessible Modals & Focus Trap Management Standard (WCAG 2.2 AA)

Accessible Modals & Focus Trap Management Standard (WCAG 2.2 AA) defines an industrial-grade behavioral standard for frontend engineering. Production accessibility engineering standard for interactive web components. Mandates strict focus trapping within open dialogs, automatic restoration of focus to triggering elements upon dismissal, Escape key closing, and screen-reader ARIA live region notifications. (WCAG 2.2 Level AA). Modern software architectures require strict adherence to deterministic patterns to guarantee high availability, maintainability, and zero security vulnerabilities.

Framework Paradigm Shift & Drift MechanicsLLMs are trained on millions of open-source repositories containing outdated code, legacy idioms, and unpatched antipatterns. When coding assistants generate implementations for this stack, they default to common statistical tokens: AI creates custom dialog modals using plain <div> tags without focus trapping or ARIA attributes, leaving keyboard and screen-reader users permanently trapped. Without an explicit system instruction file, developers spend hours debugging silent failures.
Failure Modes & Production Blast Radius

Hazard Analysis: What Breaks Without This Rule

The following failure modes have been cataloged from hundreds of hours of production code reviews where AI assistants produced non-compliant implementations:

Failure ModeAI Symptom (The Anti-Pattern)SeverityProduction Impact & Remedy
AI Hallucination & Deprecation DriftAI creates custom dialog modals using plain <div> tags without focus trapping or ARIA attributes, leaving keyboard and screen-reader users permanently trapped.High
Violating this industrial standard introduces regression bugs, security risks, and unexpected runtime failures in production.
Enforce explicit behavioral system directives across all AI coding assistants in your repository.
Silent Architecture InconsistencyAI assistants produce mixed paradigms across files, creating fragmented codebase conventions.Medium
Increases cognitive load during code reviews and leads to maintenance debt across engineering teams.
Pin project conventions in .cursor/rules, CLAUDE.md, and AGENTS.md so all team agents follow identical guardrails.
Architectural Directives in Detail

Step-by-Step Production Directives

Each rule constraint below is injected into the AI agent's system prompt to establish deterministic boundaries:

1

MUST trap tab navigation strictly inside open modal dialogs to prevent background interaction.

MUST trap tab navigation strictly inside open modal dialogs to prevent background interaction.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
2

MUST automatically return keyboard focus to the triggering element when the modal is closed.

MUST automatically return keyboard focus to the triggering element when the modal is closed.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
3

MUST assign role='dialog', aria-modal='true', and link aria-labelledby and aria-describedby to visible headings.

MUST assign role='dialog', aria-modal='true', and link aria-labelledby and aria-describedby to visible headings.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
4

MUST dismiss the modal when the user presses the 'Escape' key.

MUST dismiss the modal when the user presses the 'Escape' key.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
5

SHOULD use inert attribute on root background containers when dialogs are active.

SHOULD use inert attribute on root background containers when dialogs are active.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
Technical Questions & Answers

Frequently Asked Technical Questions

Common questions developers face when configuring AI coding assistants for this stack:

Q:Why is Accessible Modals & Focus Trap Management Standard (WCAG 2.2 AA) critical for AI coding assistants?

Production accessibility engineering standard for interactive web components. Mandates strict focus trapping within open dialogs, automatic restoration of focus to triggering elements upon dismissal, Escape key closing, and screen-reader ARIA live region notifications. (WCAG 2.2 Level AA). Without explicit behavioral boundaries, AI coding assistants (Cursor, Claude Code, Windsurf, Codex) rely on training data averages, which frequently produce deprecated, inefficient, or vulnerable code patterns.

Q:How does adopting this rule prevent AI hallucinations?

This rule explicitly declares what the AI must avoid (AI creates custom dialog modals using plain <div> tags without focus trapping or ARIA attributes, leaving keyboard and screen-reader users permanently trapped.) and prescribes verified positive examples. Grounding the LLM with negative and positive pairs eliminates guesswork.

Q:Which AI coding environments are supported?

This specification is multi-platform compatible: Cursor (.cursor/rules/*.mdc & .cursorrules), Anthropic Claude Code (CLAUDE.md), Windsurf (.windsurfrules), Codex / Cline (AGENTS.md), and GitHub Copilot (.github/copilot-instructions.md).

Q:Can I combine this rule with other technology stacks?

Yes. Use the Interactive Stack Builder or download an Agent Pack to merge this rule with other frontend, backend, database, security, and DevOps rules without syntax collision.

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