AgentRules.org
RulesStacksClientsAuditorPrunerSelf-HealRFCsBenchmarkCLICI/CDAuthorsSubmit
This specification is maintained by the AgentRules Working Group. Have enhancements or want to claim maintainership?Submit Specification →
frontendcritical PriorityID: vite6-rolldown-module-federation-singleton-isolation

Vite 6 Rolldown Module Federation Context Singleton Isolation

Enforces strict runtime singleton deduplication across micro-frontend boundaries powered by Vite 6 and Rolldown-based Module Federation. Prevents catastrophic React/Vue engine duplications, corrupted UI contexts, and broken hook dispatchers caused by loose semver matching or missing shared host fallbacks.

Prohibited Anti-Pattern: Dual-Engine Instantiation and Split React/Vue Contexts via Misconfigured Module Federation Shared Scopes

Export Ready-to-Drop Configuration

Select format below to copy code or download file directly.

---
description: Vite 6 Rolldown Module Federation Context Singleton Isolation - Enforces strict runtime singleton deduplication across micro-frontend boundaries powered by Vite 6 and Rolldown-based Module Federation. Prevents catastrophic React/Vue engine duplications, corrupted UI contexts, and broken hook dispatchers caused by loose semver matching or missing shared host fallbacks.
globs: vite.config.{ts,js,mjs}, src/bootstrap.{ts,tsx}, src/index.{ts,tsx}, src/shared/**/*.{ts,tsx}
alwaysApply: true
verified_by: "agentrules.org"
license: "CC-BY-4.0"
source: "https://agentrules.org/rules/vite6-rolldown-module-federation-singleton-isolation"
---

# Vite 6 Rolldown Module Federation Context Singleton Isolation

> **Severity**: CRITICAL | **Category**: frontend
> **Anti-Pattern Warning**: Dual-Engine Instantiation and Split React/Vue Contexts via Misconfigured Module Federation Shared Scopes

## System Constraints
You are a Principal Engineer enforcing Vite 6 Rolldown Module Federation Context Singleton Isolation. Mandate invariants that eliminate duplicate shared runtime dependencies across host-remote boundaries. Strictly reject federation configs that permit duplicate framework engines (React, Vue, Zustand, QueryClient), mismatched version ranges, or direct synchronous imports bypassing dynamic bootstrap gates.

## Strict Guidelines
- Engineers MUST ALWAYS configure `singleton: true` and `strictVersion: true` for framework core engines (`react`, `react-dom`, `vue`, `@tanstack/react-query`) within Vite/Rolldown federation plugin shared options.
- Engineers MUST ALWAYS isolate the application entrypoint behind an asynchronous dynamic `import('./bootstrap')` barrier to guarantee asynchronous shared scope negotiation completes before module execution.
- Engineers MUST NOT configure ambiguous or wildcard semver ranges (`*` or `^`) for shared singleton state engines across remote and host configuration files.
- Components NEVER consume React or Vue context instances that originate from non-shared private dependency bundles.
- Build scripts MUST validate that duplicate instances of shared singletons fail the build during Rolldown dependency graph tree-shaking and linking.

## Bad vs Good Implementations
### Module Federation Configuration with Singleton Guardrails

#### Bad Antipattern (AI Common Hallucination)
> **Why it fails**: Declaring shared dependencies as simple strings allows the Module Federation runtime to fall back to bundling duplicate React instances if host and remote semver ranges have micro-discrepancies, causing 'Invalid hook call' exceptions.
```typescript
import { defineConfig } from 'vite';
import federation from '@originjs/vite-plugin-federation';

export default defineConfig({
  plugins: [
    federation({
      name: 'remote_app',
      filename: 'remoteEntry.js',
      exposes: {
        './Widget': './src/Widget.tsx'
      },
      // ANTI-PATTERN: Incomplete shared config creates dual React instances at runtime
      shared: ['react', 'react-dom']
    })
  ]
});
```

#### Production Standard (Correct)
> **Standard**: Explicitly enforces `singleton: true` and `strictVersion: true` with an explicit semantic version constraint, guaranteeing the Rolldown/Vite runtime enforces a single dispatcher and throws compile/runtime boundary errors instead of silently duplicating runtime instances.
```typescript
import { defineConfig } from 'vite';
import { federation } from '@module-federation/vite';

export default defineConfig({
  build: {
    target: 'chrome89'
  },
  plugins: [
    federation({
      name: 'remote_app',
      filename: 'remoteEntry.js',
      exposes: {
        './Widget': './src/Widget.tsx'
      },
      shared: {
        react: {
          singleton: true,
          requiredVersion: '^18.3.1',
          strictVersion: true
        },
        'react-dom': {
          singleton: true,
          requiredVersion: '^18.3.1',
          strictVersion: true
        }
      }
    })
  ]
});
```

### Asynchronous Bootstrap Barrier to Guarantee Scope Negotiation

#### Bad Antipattern (AI Common Hallucination)
> **Why it fails**: Executing ReactDOM directly in the entry file runs prior to asynchronous shared scope initialization by the module federation runtime, forcing the bundler to load the local copy and causing split-brain singleton failures.
```typescript
// src/main.tsx (Direct synchronous bootstrap)
import React from 'react';
import ReactDOM from 'react-dom/client';
import App from './App';

// ANTI-PATTERN: Synchronously executing React before federation initializes shared scope
const root = ReactDOM.createRoot(document.getElementById('root')!);
root.render(<App />);
```

#### Production Standard (Correct)
> **Standard**: Isolating runtime mounting behind a dynamic asynchronous `import('./bootstrap')` boundary guarantees the federation container negotiates and resolves shared singleton modules prior to component evaluation.
```typescript
// src/main.tsx (Bootstrap Guard Gate)
void import('./bootstrap');

// src/bootstrap.tsx
import React from 'react';
import ReactDOM from 'react-dom/client';
import App from './App';

const container = document.getElementById('root');
if (!container) {
  throw new Error('Failed to locate mount root target');
}

const root = ReactDOM.createRoot(container);
root.render(
  <React.StrictMode>
    <App />
  </React.StrictMode>
);
```
Recommended MCP Servers (mcp-serverlist.com)

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

Vite Rolldown Module Inspector
Inspects Vite 6 Rolldown shared module dependency trees and validates singleton isolation graphs.
Recommended Agent Skills (askills.dev)

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

Module Federation Runtime Validator
CLI tool verifying remote entry schemas, cross-host semver ranges, and shared scope integrity.
Architectural Specification & Invariant Rationale

Architectural Invariant Design: Vite 6 Rolldown Module Federation Context Singleton Isolation

Vite 6 Rolldown Module Federation Context Singleton Isolation defines an industrial-grade behavioral standard for frontend engineering. Enforces strict runtime singleton deduplication across micro-frontend boundaries powered by Vite 6 and Rolldown-based Module Federation. Prevents catastrophic React/Vue engine duplications, corrupted UI contexts, and broken hook dispatchers caused by loose semver matching or missing shared host fallbacks. 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: Dual-Engine Instantiation and Split React/Vue Contexts via Misconfigured Module Federation Shared Scopes 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 DriftDual-Engine Instantiation and Split React/Vue Contexts via Misconfigured Module Federation Shared ScopesCritical
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

Engineers MUST ALWAYS configure `singleton

Engineers MUST ALWAYS configure `singleton: true` and `strictVersion: true` for framework core engines (`react`, `react-dom`, `vue`, `@tanstack/react-query`) within Vite/Rolldown federation plugin shared options.

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

Engineers MUST ALWAYS isolate the application entrypoint behind an asynchronous dynamic `import('./bootstrap')` barrier to guarantee asynchronous shared scope negotiation completes before module execution.

Engineers MUST ALWAYS isolate the application entrypoint behind an asynchronous dynamic `import('./bootstrap')` barrier to guarantee asynchronous shared scope negotiation completes before module execution.

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

Engineers MUST NOT configure ambiguous or wildcard semver ranges (`*` or `^`) for shared singleton state engines across remote and host configuration files.

Engineers MUST NOT configure ambiguous or wildcard semver ranges (`*` or `^`) for shared singleton state engines across remote and host configuration files.

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

Components NEVER consume React or Vue context instances that originate from non-shared private dependency bundles.

Components NEVER consume React or Vue context instances that originate from non-shared private dependency bundles.

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

Build scripts MUST validate that duplicate instances of shared singletons fail the build during Rolldown dependency graph tree-shaking and linking.

Build scripts MUST validate that duplicate instances of shared singletons fail the build during Rolldown dependency graph tree-shaking and linking.

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 Vite 6 Rolldown Module Federation Context Singleton Isolation critical for AI coding assistants?

Enforces strict runtime singleton deduplication across micro-frontend boundaries powered by Vite 6 and Rolldown-based Module Federation. Prevents catastrophic React/Vue engine duplications, corrupted UI contexts, and broken hook dispatchers caused by loose semver matching or missing shared host fallbacks. 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 (Dual-Engine Instantiation and Split React/Vue Contexts via Misconfigured Module Federation Shared Scopes) 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.

Open Specification · CC BY 4.0·Free for Personal, Team & Commercial In-Repo Use

Citation & Open Source Attribution Guidelines

This specification is licensed under Creative Commons Attribution 4.0 International (CC BY 4.0). You are completely free to adapt and share this rule in your workspace. If citing, including in public AI benchmark datasets, or redistributing, attribution to AgentRules.org is required.

Related FRONTEND Rules

View all rules →
frontend
119

SolidStart 1.0 Server Functions & Async Boundaries Production Standard

SolidStart 1.0 relies on the Vinxi bundler to split `server$` closures into independent HTTP POST RPC endpoints. Direct lexical closure over client signals within `server$` scopes or failure to demarcate async boundaries with `<Suspense>` causes silent serialization failures, client-bundle secret leaks, and SSR hydration mismatches. Enforcing strict parameter passing, runtime input validation, and Solid async primitives maintains security and fine-grained reactivity across network boundaries.

frontend
119

Astro 5 Actions & Content Layer Production Standard

Enforces strict type safety and architectural correctness for Astro 5 Server Actions and the zero-waterfall Content Layer API. Prevents runtime contract mismatches, hydration mismatches, and unhandled mutation exceptions across dynamic and prerendered boundaries. Failure to follow these patterns leads to silent data fetching waterfalls, build-time cache corruptions, and unhandled server action exceptions.

frontend
51

Nuxt 4 Nitro Server Engine & Shared Directory Production Standard

Nuxt 4 enforces strict boundary segregation between client UI in the app/ directory, backend endpoints in server/, and universal contracts in shared/. Violating cross-boundary isolation or maintaining module-scoped state in Nitro server handlers causes catastrophic cross-request data corruption and hydration mismatches under concurrent production traffic. Architects must enforce request-isolated H3 event contexts, universal serialization schemas, and strict path-alias boundaries.

1 Rule in Stack

Vite