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frontendcritical PriorityID: module-federation-2-remote-integrity-singleton-guardrail

Module Federation 2.0 Dynamic Remote Integrity & Shared Dependency Guardrail

Enforces cryptographic manifest validation, subresource integrity (SRI), and strict semver singleton resolution when dynamically loading Module Federation 2.0 remotes across heterogeneous CDNs. Prevents supply-chain remote hijacking and dual-instantiation runtime crashes in shared runtime singletons like React, React-DOM, and state managers. Mandates centralized federation runtime plugins for dynamic URL ingestion and error boundary fallbacks.

Prohibited Anti-Pattern: Unvalidated Remote Script Injection with Unpinned Shared Singleton Collisions

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---
description: Module Federation 2.0 Dynamic Remote Integrity & Shared Dependency Guardrail - Enforces cryptographic manifest validation, subresource integrity (SRI), and strict semver singleton resolution when dynamically loading Module Federation 2.0 remotes across heterogeneous CDNs. Prevents supply-chain remote hijacking and dual-instantiation runtime crashes in shared runtime singletons like React, React-DOM, and state managers. Mandates centralized federation runtime plugins for dynamic URL ingestion and error boundary fallbacks.
globs: **/module-federation.config.{ts,js}, **/rspack.config.{ts,js}, **/webpack.config.{ts,js}, src/**/remoteEntry.{ts,js}, src/**/federation/**/*.{ts,tsx}
alwaysApply: true
verified_by: "agentrules.org"
license: "CC-BY-4.0"
source: "https://agentrules.org/rules/module-federation-2-remote-integrity-singleton-guardrail"
---

# Module Federation 2.0 Dynamic Remote Integrity & Shared Dependency Guardrail

> **Severity**: CRITICAL | **Category**: frontend
> **Anti-Pattern Warning**: Unvalidated Remote Script Injection with Unpinned Shared Singleton Collisions

## System Constraints
You are a Principal Software Architect enforcing Module Federation 2.0 dynamic remote integrity and shared singleton stability. You must reject raw string URL dynamic remote bindings, missing Subresource Integrity (SRI) hashes in remote manifests, and un-scoped or un-versioned shared dependencies. Ensure all micro-frontend boundaries leverage @module-federation/runtime plugins to cryptographically verify remote assets and explicitly handle singleton version conflicts via strict semver constraints.

## Strict Guidelines
- Engineers MUST ALWAYS configure critical runtime singletons ('react', 'react-dom', state management contexts) with 'singleton: true', 'strictVersion: true', and a fixed 'requiredVersion' matching package.json.
- Engineers MUST NOT inject dynamic remote entry scripts directly via DOM script tags or unverified 'window' mutations.
- Engineers MUST configure Module Federation 2.0 runtime plugins to intercept remote resolution and validate manifests using cryptographic digests or signed manifests before module execution.
- Code SHOULD implement comprehensive async React Error Boundaries around dynamically loaded federated remotes with declarative fallback UIs.
- Services MUST define an allowlist of permitted CDN origins for remote manifests to eliminate cross-origin arbitrary code execution.

## Bad vs Good Implementations
### Module Federation 2.0 Shared Config and Dynamic Remote Resolution

#### Bad Antipattern (AI Common Hallucination)
> **Why it fails**: Directly loading arbitrary CDN URLs without manifest validation exposes the application to supply-chain tampering and remote execution vulnerabilities. Setting 'singleton: false' on React causes multiple instances to exist simultaneously, corrupting React hooks and context state.
```typescript
import { init, loadRemote } from '@module-federation/runtime';

// ANTI-PATTERN: Dynamically injecting untrusted remote without SRI or origin validation,
// and using loose shared singleton rules that cause dual-React runtime crashes.
export async function mountUntrustedRemote(cdnUrl: string) {
  init({
    name: 'host_app',
    remotes: [
      {
        name: 'remote_app',
        entry: cdnUrl, // Blind injection from runtime argument
      },
    ],
    shared: {
      react: { singleton: false }, // Disables singleton check, breaks React context/hooks
      'react-dom': { singleton: false },
    },
  });

  return loadRemote('remote_app/Widget');
}
```

#### Production Standard (Correct)
> **Standard**: Validates CDN origins through a runtime plugin before loading dynamic entry points. Configures React and React-DOM as strict singletons constrained to the exact host semver, preventing hook failure and dual-state runtime collisions.
```typescript
import { init, loadRemote, FederationRuntimePlugin } from '@module-federation/runtime';
import packageJson from '../package.json';

const TRUSTED_DOMAINS = new Set(['https://cdn.corp.enterprise.com', 'https://static.microfrontend.internal']);

// Cryptographic integrity enforcement plugin for MF 2.0
const integrityPlugin: () => FederationRuntimePlugin = () => ({
  name: 'remote-integrity-guard-plugin',
  beforeLoadRemote(args) {
    const url = new URL(args.options.entry, window.location.href);
    if (!TRUSTED_DOMAINS.has(url.origin)) {
      throw new SecurityError(`Untrusted remote domain: ${url.origin}`);
    }
    return args;
  },
});

export function initializeFederationHost() {
  init({
    name: 'host_app',
    plugins: [integrityPlugin()],
    shared: {
      react: {
        singleton: true,
        strictVersion: true,
        requiredVersion: packageJson.dependencies.react,
        eager: false,
      },
      'react-dom': {
        singleton: true,
        strictVersion: true,
        requiredVersion: packageJson.dependencies['react-dom'],
        eager: false,
      },
    },
  });
}

export async function loadSecureWidget() {
  initializeFederationHost();
  return loadRemote<React.ComponentType>('remote_app/Widget');
}
```
Recommended MCP Servers (mcp-serverlist.com)

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

Fetch MCP Server
Performs authenticated remote manifest inspection and header validation for dynamic federation endpoints.
Recommended Agent Skills (askills.dev)

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

Rspack CLI
Validates and builds Module Federation 2.0 configurations with automated dependency and singleton graph validation.
Architectural Specification & Invariant Rationale

Architectural Invariant Design: Module Federation 2.0 Dynamic Remote Integrity & Shared Dependency Guardrail

Module Federation 2.0 Dynamic Remote Integrity & Shared Dependency Guardrail defines an industrial-grade behavioral standard for frontend engineering. Enforces cryptographic manifest validation, subresource integrity (SRI), and strict semver singleton resolution when dynamically loading Module Federation 2.0 remotes across heterogeneous CDNs. Prevents supply-chain remote hijacking and dual-instantiation runtime crashes in shared runtime singletons like React, React-DOM, and state managers. Mandates centralized federation runtime plugins for dynamic URL ingestion and error boundary 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: Unvalidated Remote Script Injection with Unpinned Shared Singleton Collisions 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 DriftUnvalidated Remote Script Injection with Unpinned Shared Singleton CollisionsCritical
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 critical runtime singletons ('react', 'react-dom', state management contexts) with 'singleton

Engineers MUST ALWAYS configure critical runtime singletons ('react', 'react-dom', state management contexts) with 'singleton: true', 'strictVersion: true', and a fixed 'requiredVersion' matching package.json.

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 NOT inject dynamic remote entry scripts directly via DOM script tags or unverified 'window' mutations.

Engineers MUST NOT inject dynamic remote entry scripts directly via DOM script tags or unverified 'window' mutations.

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 configure Module Federation 2.0 runtime plugins to intercept remote resolution and validate manifests using cryptographic digests or signed manifests before module execution.

Engineers MUST configure Module Federation 2.0 runtime plugins to intercept remote resolution and validate manifests using cryptographic digests or signed manifests 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.
4

Code SHOULD implement comprehensive async React Error Boundaries around dynamically loaded federated remotes with declarative fallback UIs.

Code SHOULD implement comprehensive async React Error Boundaries around dynamically loaded federated remotes with declarative fallback UIs.

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

Services MUST define an allowlist of permitted CDN origins for remote manifests to eliminate cross-origin arbitrary code execution.

Services MUST define an allowlist of permitted CDN origins for remote manifests to eliminate cross-origin arbitrary code 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.
Technical Questions & Answers

Frequently Asked Technical Questions

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

Q:Why is Module Federation 2.0 Dynamic Remote Integrity & Shared Dependency Guardrail critical for AI coding assistants?

Enforces cryptographic manifest validation, subresource integrity (SRI), and strict semver singleton resolution when dynamically loading Module Federation 2.0 remotes across heterogeneous CDNs. Prevents supply-chain remote hijacking and dual-instantiation runtime crashes in shared runtime singletons like React, React-DOM, and state managers. Mandates centralized federation runtime plugins for dynamic URL ingestion and error boundary 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 (Unvalidated Remote Script Injection with Unpinned Shared Singleton Collisions) 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

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