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: vite-6-rolldown-environment-api-boundary-invariant

Vite 6 Rolldown Environment API Isomorphic Boundary Invariant

Mandates absolute runtime module isolation across Vite 6 Environment API compilation units (Client, SSR, Edge/Workerd, WebWorker) to prevent cross-runtime module graph pollution. Prohibits heuristic runtime environment branch sniffing in shared bundles and enforces strict Rolldown build-time condition mapping and chunk graph separation.

Prohibited Anti-Pattern: Ambient Runtime Guards and Monolithic Chunks Polluting Vite 6 Multi-Environment Graphs

Export Ready-to-Drop Configuration

Select format below to copy code or download file directly.

---
description: Vite 6 Rolldown Environment API Isomorphic Boundary Invariant - Mandates absolute runtime module isolation across Vite 6 Environment API compilation units (Client, SSR, Edge/Workerd, WebWorker) to prevent cross-runtime module graph pollution. Prohibits heuristic runtime environment branch sniffing in shared bundles and enforces strict Rolldown build-time condition mapping and chunk graph separation.
globs: vite.config.ts, vite.config.*.ts, src/**/*.{ts,tsx}, packages/**/*.{ts,tsx}
alwaysApply: true
verified_by: "agentrules.org"
license: "CC-BY-4.0"
source: "https://agentrules.org/rules/vite-6-rolldown-environment-api-boundary-invariant"
---

# Vite 6 Rolldown Environment API Isomorphic Boundary Invariant

> **Severity**: CRITICAL | **Category**: frontend
> **Anti-Pattern Warning**: Ambient Runtime Guards and Monolithic Chunks Polluting Vite 6 Multi-Environment Graphs

## System Constraints
You are a Principal Software Architect enforcing Vite 6 Rolldown Environment API Isomorphic Boundary Invariants. Mandate strict module graph isolation across distinct compilation environments (client, ssr, edge, webworker). Reject all dynamic runtime environment sniffing (such as typeof window !== 'undefined') in shared libraries; enforce static compilation barriers via package.json conditional exports and explicit Vite 6 environments definitions.

## Strict Guidelines
- Engineers MUST ALWAYS configure discrete execution targets using Vite 6 `environments` (e.g., `client`, `ssr`, `edge`) instead of legacy monolithic client/ssr dual builds.
- Engineers MUST NOT rely on runtime conditional checks (`typeof window !== 'undefined'`, `typeof process !== 'undefined'`) to guard platform-specific code inside isomorphic modules; Rolldown will trace and potentially hoist incompatible imports into shared chunks.
- Code targeting different runtimes MUST be isolated into distinct subpath exports or packages using conditional exports (`browser`, `edge-light`, `node`, `worker`) in `package.json`.
- Shared utilities MUST NOT retain mutable module-level state or instantiate platform-bound singletons (e.g., node:crypto or window.indexedDB) within the module evaluation phase.
- Rollup/Rolldown output configurations within Vite 6 MUST specify explicit chunking keys per environment to prevent cross-environment chunk deduplication and identifier collision.
- Every Vite plugin registered across multiple environments MUST implement environment hooks (`buildStart`, `resolveId`, `load`) using `this.environment.name` to guard against ambient transformation leaks.

## Bad vs Good Implementations
### Vite 6 Multi-Environment Configuration & Platform Boundary Resolution

#### Bad Antipattern (AI Common Hallucination)
> **Why it fails**: Legacy Vite SSR configurations treat the module graph as a simple client/server binary. Shared dependencies like 'shared-lib' containing runtime branches ('typeof window') can leak Node.js internals or DOM globals into non-compatible runtimes, and Rolldown's static analysis cannot reliably prune dead environment branches when packaged in unified chunks.
```typescript
// vite.config.ts - Antipattern: Mixing runtimes without Environment API isolation
import { defineConfig } from 'vite';

export default defineConfig({
  ssr: {
    // Ambient SSR mixing Node and Edge logic
    noExternal: ['shared-lib'],
  },
  build: {
    rollupOptions: {
      // Single output target assuming browser/node parity
      output: {
        manualChunks: {
          vendor: ['shared-lib'],
        },
      },
    },
  },
});
```

#### Production Standard (Correct)
> **Standard**: The Vite 6 Environment API isolates client, node SSR, and edge environments into distinct compilation pipelines. Each environment maintains independent module resolution conditions and distinct Rolldown output targets, eliminating cross-runtime chunk sharing and guarantee-breaking module pollution.
```typescript
// vite.config.ts - Production standard: Vite 6 Rolldown Environment API isolation
import { defineConfig } from 'vite';

export default defineConfig({
  environments: {
    client: {
      build: {
        outDir: 'dist/client',
        rollupOptions: {
          output: {
            entryFileNames: 'assets/[name]-[hash].js',
            chunkFileNames: 'assets/chunks/[name]-[hash].js',
          },
        },
      },
      resolve: {
        conditions: ['browser', 'module'],
      },
    },
    ssr: {
      build: {
        outDir: 'dist/server',
      },
      resolve: {
        conditions: ['node', 'import'],
      },
    },
    edge: {
      build: {
        outDir: 'dist/edge',
      },
      resolve: {
        conditions: ['edge-light', 'worker', 'import'],
        noExternal: true,
      },
    },
  },
});
```

### Platform Storage Abstraction Boundary

#### Bad Antipattern (AI Common Hallucination)
> **Why it fails**: Direct static imports of 'node:fs' contaminate the AST during Rolldown bundling. Even if wrapped in runtime 'typeof window' checks, static bundlers will bundle or externalize the import incorrectly for Edge or Client bundles, triggering runtime crashes or bundle inflation.
```typescript
// src/shared/storage.ts - Antipattern: Monolithic isomorphic runtime branching
import fs from 'node:fs';

export function getSessionData(key: string): string | null {
  if (typeof window !== 'undefined') {
    return window.localStorage.getItem(key);
  }
  // Runtime will crash on Cloudflare Workers (edge) or fail in browser bundling
  if (fs.existsSync(`/tmp/${key}`)) {
    return fs.readFileSync(`/tmp/${key}`, 'utf-8');
  }
  return null;
}
```

#### Production Standard (Correct)
> **Standard**: Decoupling runtime dependencies via abstract interfaces and target-specific implementations ensures Rolldown only bundles code supported by the target environment conditions defined in package.json and vite.config.ts.
```typescript
// src/shared/storage.interface.ts
export interface StorageProvider {
  getItem(key: string): Promise<string | null>;
}

// src/shared/storage.browser.ts
export const storageProvider: StorageProvider = {
  async getItem(key: string) {
    return window.localStorage.getItem(key);
  },
};

// src/shared/storage.edge.ts
export const storageProvider: StorageProvider = {
  async getItem(key: string) {
    // Cloudflare Workers / Edge key-value implementation
    return (globalThis as unknown as { EDGE_KV: { get(k: string): Promise<string | null> } }).EDGE_KV.get(key);
  },
};
```
Recommended MCP Servers (mcp-serverlist.com)

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

Local Filesystem Inspector
Inspects directory structures, package.json export conditions, and Vite build outputs.
Recommended Agent Skills (askills.dev)

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

Publint Packaging Linter
Verifies package.json conditional exports match runtime expectations across browser, node, and worker targets.
Architectural Specification & Invariant Rationale

Architectural Invariant Design: Vite 6 Rolldown Environment API Isomorphic Boundary Invariant

Vite 6 Rolldown Environment API Isomorphic Boundary Invariant defines an industrial-grade behavioral standard for frontend engineering. Mandates absolute runtime module isolation across Vite 6 Environment API compilation units (Client, SSR, Edge/Workerd, WebWorker) to prevent cross-runtime module graph pollution. Prohibits heuristic runtime environment branch sniffing in shared bundles and enforces strict Rolldown build-time condition mapping and chunk graph separation. 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: Ambient Runtime Guards and Monolithic Chunks Polluting Vite 6 Multi-Environment Graphs 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 DriftAmbient Runtime Guards and Monolithic Chunks Polluting Vite 6 Multi-Environment GraphsCritical
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 discrete execution targets using Vite 6 `environments` (e.g., `client`, `ssr`, `edge`) instead of legacy monolithic client/ssr dual builds.

Engineers MUST ALWAYS configure discrete execution targets using Vite 6 `environments` (e.g., `client`, `ssr`, `edge`) instead of legacy monolithic client/ssr dual builds.

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 rely on runtime conditional checks (`typeof window !== 'undefined'`, `typeof process !== 'undefined'`) to guard platform-specific code inside isomorphic modules

Engineers MUST NOT rely on runtime conditional checks (`typeof window !== 'undefined'`, `typeof process !== 'undefined'`) to guard platform-specific code inside isomorphic modules; Rolldown will trace and potentially hoist incompatible imports into shared chunks.

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

Code targeting different runtimes MUST be isolated into distinct subpath exports or packages using conditional exports (`browser`, `edge-light`, `node`, `worker`) in `package.json`.

Code targeting different runtimes MUST be isolated into distinct subpath exports or packages using conditional exports (`browser`, `edge-light`, `node`, `worker`) in `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.
4

Shared utilities MUST NOT retain mutable module-level state or instantiate platform-bound singletons (e.g., node

Shared utilities MUST NOT retain mutable module-level state or instantiate platform-bound singletons (e.g., node:crypto or window.indexedDB) within the module evaluation phase.

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

Rollup/Rolldown output configurations within Vite 6 MUST specify explicit chunking keys per environment to prevent cross-environment chunk deduplication and identifier collision.

Rollup/Rolldown output configurations within Vite 6 MUST specify explicit chunking keys per environment to prevent cross-environment chunk deduplication and identifier collision.

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.
6

Every Vite plugin registered across multiple environments MUST implement environment hooks (`buildStart`, `resolveId`, `load`) using `this.environment.name` to guard against ambient transformation leaks.

Every Vite plugin registered across multiple environments MUST implement environment hooks (`buildStart`, `resolveId`, `load`) using `this.environment.name` to guard against ambient transformation leaks.

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 Environment API Isomorphic Boundary Invariant critical for AI coding assistants?

Mandates absolute runtime module isolation across Vite 6 Environment API compilation units (Client, SSR, Edge/Workerd, WebWorker) to prevent cross-runtime module graph pollution. Prohibits heuristic runtime environment branch sniffing in shared bundles and enforces strict Rolldown build-time condition mapping and chunk graph separation. 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 (Ambient Runtime Guards and Monolithic Chunks Polluting Vite 6 Multi-Environment Graphs) 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