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-environment-api-multi-runtime-sandbox

Vite 6 Multi-Runtime Environment Isolation & Global Sandbox Standard

Mandates isolated environment execution contexts using the Vite 6 Environment API across Node.js, Cloudflare Workerd, and Edge runtimes during SSR bundling. Prevents cross-runtime globalThis pollution, leakage of Node.js globals (Buffer, process) into edge isolates, and shared module graph corruption.

Prohibited Anti-Pattern: Monolithic SSR configuration leaking Node.js primitives into Edge/Workerd runtimes via unisolated shared module graphs.

Export Ready-to-Drop Configuration

Select format below to copy code or download file directly.

---
description: Vite 6 Multi-Runtime Environment Isolation & Global Sandbox Standard - Mandates isolated environment execution contexts using the Vite 6 Environment API across Node.js, Cloudflare Workerd, and Edge runtimes during SSR bundling. Prevents cross-runtime globalThis pollution, leakage of Node.js globals (Buffer, process) into edge isolates, and shared module graph corruption.
globs: vite.config.ts, vite.config.js, src/**/*.{ts,tsx}, server/**/*.{ts,tsx}
alwaysApply: true
verified_by: "agentrules.org"
license: "CC-BY-4.0"
source: "https://agentrules.org/rules/vite6-environment-api-multi-runtime-sandbox"
---

# Vite 6 Multi-Runtime Environment Isolation & Global Sandbox Standard

> **Severity**: CRITICAL | **Category**: frontend
> **Anti-Pattern Warning**: Monolithic SSR configuration leaking Node.js primitives into Edge/Workerd runtimes via unisolated shared module graphs.

## System Constraints
You are a Principal Engineer enforcing the Vite 6 Environment API Multi-Runtime Execution Sandbox. Mandate strict environment boundary separation between client, node ssr, and workerd/edge runtimes. Prevent global scope leakage, incorrect resolve conditions, and cross-runtime contamination during bundling and SSR dev execution.

## Strict Guidelines
- Engineers MUST ALWAYS declare explicit `environments` in `vite.config.ts` separating `client`, `ssr` (Node.js), and `edge`/`workerd` runtimes with distinct `resolve.conditions`.
- Engineers MUST NOT rely on legacy monolithic Vite SSR configurations or single-graph bundling that mixes Node.js built-ins into edge worker targets.
- Code SHOULD configure runtime-specific resolution conditions (e.g., `['workerd', 'worker']` for Cloudflare Workers versus `['node']` for Node SSR) to ensure correct module export selection.
- Services MUST isolate runtime instances using Vite 6 `DevEnvironment` runners or environment-specific dispatchers rather than polyfilling `globalThis` globally across all environments.
- Components NEVER import runtime-specific globals (e.g., `process.env`, `Buffer`, `navigator.userAgent`) directly without compile-time environment guards or environment adapter contracts.

## Bad vs Good Implementations
### Multi-Runtime Environment Configuration with Vite 6 Environment API

#### Bad Antipattern (AI Common Hallucination)
> **Why it fails**: Legacy Vite SSR setups treat server execution as a single monolithic environment. Setting `target: 'webworker'` globally breaks Node.js SSR requirements, while polyfilling `process.env` and `global` contaminates the global scope and leads to silent runtime failures in strict V8 isolates (e.g., Workerd).
```typescript
import { defineConfig } from 'vite';

// ANTI-PATTERN: Monolithic configuration with shared SSR target.
// Node built-ins leak into edge runtime; export conditions conflict across environments.
export default defineConfig({
  ssr: {
    noExternal: true,
    target: 'webworker',
  },
  define: {
    // Pollutes global scope across both client and edge/node builds
    'process.env': {},
    'global': 'globalThis',
  },
  build: {
    ssr: 'src/entry-server.ts',
  },
});
```

#### Production Standard (Correct)
> **Standard**: Leverages Vite 6's Environment API to assign distinct module graphs, export resolution conditions, and target outputs to `client`, `ssr` (Node), and `edge` (Workerd). This guarantees runtime isolation and prevents Node built-in leakage into edge isolates.
```typescript
import { defineConfig } from 'vite';

// PRODUCTION STANDARD: Vite 6 Environment API isolation
export default defineConfig({
  environments: {
    client: {
      consumer: 'client',
      build: {
        outDir: 'dist/client',
      },
    },
    ssr: {
      consumer: 'server',
      resolve: {
        conditions: ['node', 'import'],
        externalConditions: ['node'],
      },
      build: {
        outDir: 'dist/ssr',
        ssr: 'src/entry-node.ts',
      },
    },
    edge: {
      consumer: 'server',
      resolve: {
        noExternal: true,
        conditions: ['workerd', 'worker', 'browser'],
      },
      build: {
        outDir: 'dist/edge',
        ssr: 'src/entry-edge.ts',
      },
    },
  },
});
```
Recommended MCP Servers (mcp-serverlist.com)

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

Filesystem MCP
Inspect and validate Vite configuration files and directory structures across multi-runtime targets.
Recommended Agent Skills (askills.dev)

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

Vite CLI Tooling
Run and verify environment builds and dev servers using Vite 6 Environment APIs.
Architectural Specification & Invariant Rationale

Architectural Invariant Design: Vite 6 Multi-Runtime Environment Isolation & Global Sandbox Standard

Vite 6 Multi-Runtime Environment Isolation & Global Sandbox Standard defines an industrial-grade behavioral standard for frontend engineering. Mandates isolated environment execution contexts using the Vite 6 Environment API across Node.js, Cloudflare Workerd, and Edge runtimes during SSR bundling. Prevents cross-runtime globalThis pollution, leakage of Node.js globals (Buffer, process) into edge isolates, and shared module graph corruption. 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: Monolithic SSR configuration leaking Node.js primitives into Edge/Workerd runtimes via unisolated shared module 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 DriftMonolithic SSR configuration leaking Node.js primitives into Edge/Workerd runtimes via unisolated shared module graphs.Critical
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 declare explicit `environments` in `vite.config.ts` separating `client`, `ssr` (Node.js), and `edge`/`workerd` runtimes with distinct `resolve.conditions`.

Engineers MUST ALWAYS declare explicit `environments` in `vite.config.ts` separating `client`, `ssr` (Node.js), and `edge`/`workerd` runtimes with distinct `resolve.conditions`.

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 legacy monolithic Vite SSR configurations or single-graph bundling that mixes Node.js built-ins into edge worker targets.

Engineers MUST NOT rely on legacy monolithic Vite SSR configurations or single-graph bundling that mixes Node.js built-ins into edge worker targets.

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 SHOULD configure runtime-specific resolution conditions (e.g., `['workerd', 'worker']` for Cloudflare Workers versus `['node']` for Node SSR) to ensure correct module export selection.

Code SHOULD configure runtime-specific resolution conditions (e.g., `['workerd', 'worker']` for Cloudflare Workers versus `['node']` for Node SSR) to ensure correct module export selection.

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

Services MUST isolate runtime instances using Vite 6 `DevEnvironment` runners or environment-specific dispatchers rather than polyfilling `globalThis` globally across all environments.

Services MUST isolate runtime instances using Vite 6 `DevEnvironment` runners or environment-specific dispatchers rather than polyfilling `globalThis` globally across all environments.

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

Components NEVER import runtime-specific globals (e.g., `process.env`, `Buffer`, `navigator.userAgent`) directly without compile-time environment guards or environment adapter contracts.

Components NEVER import runtime-specific globals (e.g., `process.env`, `Buffer`, `navigator.userAgent`) directly without compile-time environment guards or environment adapter contracts.

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 Multi-Runtime Environment Isolation & Global Sandbox Standard critical for AI coding assistants?

Mandates isolated environment execution contexts using the Vite 6 Environment API across Node.js, Cloudflare Workerd, and Edge runtimes during SSR bundling. Prevents cross-runtime globalThis pollution, leakage of Node.js globals (Buffer, process) into edge isolates, and shared module graph corruption. 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 (Monolithic SSR configuration leaking Node.js primitives into Edge/Workerd runtimes via unisolated shared module 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