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frontendcritical PriorityID: vite-6-environment-api-multi-runtime-isolation-vite-6-environme-825

Vite 6 Environment API Multi-Runtime Module Execution Boundary

Enforces strict isolation between client, worker/edge (e.g., Workerd), and Node.js execution runtimes when configuring Vite 6 multi-environment pipelines. Prevents cross-environment module graph leakage, improper resolve condition inheritance, and runtime host crash hazards caused by calling legacy SSR APIs in multi-target architectures.

Prohibited Anti-Pattern: Leaking Node.js Built-ins and Shared Module Graphs into Edge Runtimes via Legacy Vite SSR APIs

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---
description: Vite 6 Environment API Multi-Runtime Module Execution Boundary - Enforces strict isolation between client, worker/edge (e.g., Workerd), and Node.js execution runtimes when configuring Vite 6 multi-environment pipelines. Prevents cross-environment module graph leakage, improper resolve condition inheritance, and runtime host crash hazards caused by calling legacy SSR APIs in multi-target architectures.
globs: vite.config.{ts,js,mjs}, src/**/*.{ts,tsx}, server/**/*.{ts,js}
alwaysApply: true
verified_by: "agentrules.org"
license: "CC-BY-4.0"
source: "https://agentrules.org/rules/vite-6-environment-api-multi-runtime-isolation-vite-6-environme-825"
---

# Vite 6 Environment API Multi-Runtime Module Execution Boundary

> **Severity**: CRITICAL | **Category**: frontend
> **Anti-Pattern Warning**: Leaking Node.js Built-ins and Shared Module Graphs into Edge Runtimes via Legacy Vite SSR APIs

## System Constraints
You are a Principal Software Architect enforcing runtime module boundaries in Vite 6 multi-environment applications. You must mandate the strict usage of the Vite 6 Environment API (environments configuration and DevEnvironment runners) to isolate module graphs, resolve conditions, and runtime execution contexts across Node.js, Edge, and browser targets.

## Strict Guidelines
- Engineers MUST ALWAYS configure runtime-specific resolution via `environments.<name>.resolve.conditions` (e.g., `['workerd', 'worker']` for edge vs `['node']` for ssr) instead of top-level resolve conditions.
- Engineers MUST NOT call deprecated monolithic APIs like `server.ssrLoadModule` or `server.ssrFixStacktrace` in multi-runtime applications; target environments MUST be accessed via `server.environments[name].runner.importModule()`.
- Code executing in Edge/Worker environments MUST NOT reference Node.js built-ins (`node:fs`, `node:path`, `node:child_process`) unless explicitly shimmed through the environment's `resolve.alias` or `optimizeDeps` boundary.
- Plugins MUST utilize per-environment hooks (`buildStart`, `resolveId`, `load`) by inspecting `this.environment.name` instead of assuming a single global SSR compilation pass.
- Dev server entry points MUST instantiate isolated `DevEnvironment` or `RunnableDevEnvironment` instances with dedicated runtime transports to prevent process-level global scope pollution.

## Bad vs Good Implementations
### Configuring Multi-Environment Runtimes and Dynamic Module Execution

#### Bad Antipattern (AI Common Hallucination)
> **Why it fails**: Declaring mixed resolve conditions at the root level contaminates both runtimes. Calling legacy server.ssrLoadModule() executes edge worker modules directly inside the Node.js host process without runtime-specific globals, failing to catch workerd/edge incompatibilities.
```typescript
import { defineConfig, createServer } from 'vite';

// ANTI-PATTERN: Monolithic SSR configuration mixing Node and Edge targets
export default defineConfig({
  ssr: {
    noExternal: true,
    target: 'webworker',
  },
  resolve: {
    conditions: ['worker', 'node'], // Contaminated resolution conditions
  },
});

async function handleRequest(url: string) {
  const server = await createServer();
  // DANGER: Deprecated server.ssrLoadModule loads into the host Node.js process,
  // ignoring worker constraints and polluting the global execution context.
  const entry = await server.ssrLoadModule('./src/entry-edge.ts');
  return entry.default(url);
}
```

#### Production Standard (Correct)
> **Standard**: Explicitly declares dedicated client, nodeSsr, and edge environments with runtime-specific resolve conditions. Uses server.environments.edge.runner.importModule() to guarantee that module transformations and executions adhere strictly to the target environment's sandbox.
```typescript
import { defineConfig, createServer } from 'vite';

// PRODUCTION FIX: Explicit Vite 6 Environment API separation
export default defineConfig({
  environments: {
    client: {
      build: { outDir: 'dist/client' },
    },
    nodeSsr: {
      resolve: { conditions: ['node'] },
      build: { outDir: 'dist/node' },
    },
    edge: {
      resolve: { conditions: ['workerd', 'worker'] },
      build: {
        outDir: 'dist/edge',
        rollupOptions: { input: './src/entry-edge.ts' },
      },
      consumer: 'server',
    },
  },
});

async function handleEdgeRequest(url: string) {
  const server = await createServer();
  const edgeEnv = server.environments.edge;
  
  if (!edgeEnv || !('runner' in edgeEnv)) {
    throw new Error('Edge environment runner is not configured');
  }

  // Correct: Dispatch to the specific environment module runner
  const entry = await edgeEnv.runner.importModule('./src/entry-edge.ts');
  return entry.default(url);
}
```
Recommended MCP Servers (mcp-serverlist.com)

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

Filesystem MCP
Inspect and validate project directory structures and runtime bundle boundaries.
Recommended Agent Skills (askills.dev)

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

Vite Multi-Environment Build Verifier
Runs Vite 6 builds with environment-specific bundle target verification.
Architectural Specification & Invariant Rationale

Architectural Invariant Design: Vite 6 Environment API Multi-Runtime Module Execution Boundary

Vite 6 Environment API Multi-Runtime Module Execution Boundary defines an industrial-grade behavioral standard for frontend engineering. Enforces strict isolation between client, worker/edge (e.g., Workerd), and Node.js execution runtimes when configuring Vite 6 multi-environment pipelines. Prevents cross-environment module graph leakage, improper resolve condition inheritance, and runtime host crash hazards caused by calling legacy SSR APIs in multi-target architectures. 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: Leaking Node.js Built-ins and Shared Module Graphs into Edge Runtimes via Legacy Vite SSR APIs 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 DriftLeaking Node.js Built-ins and Shared Module Graphs into Edge Runtimes via Legacy Vite SSR APIsCritical
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 runtime-specific resolution via `environments.<name>.resolve.conditions` (e.g., `['workerd', 'worker']` for edge vs `['node']` for ssr) instead of top-level resolve conditions.

Engineers MUST ALWAYS configure runtime-specific resolution via `environments.<name>.resolve.conditions` (e.g., `['workerd', 'worker']` for edge vs `['node']` for ssr) instead of top-level 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 call deprecated monolithic APIs like `server.ssrLoadModule` or `server.ssrFixStacktrace` in multi-runtime applications

Engineers MUST NOT call deprecated monolithic APIs like `server.ssrLoadModule` or `server.ssrFixStacktrace` in multi-runtime applications; target environments MUST be accessed via `server.environments[name].runner.importModule()`.

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 executing in Edge/Worker environments MUST NOT reference Node.js built-ins (`node

Code executing in Edge/Worker environments MUST NOT reference Node.js built-ins (`node:fs`, `node:path`, `node:child_process`) unless explicitly shimmed through the environment's `resolve.alias` or `optimizeDeps` boundary.

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

Plugins MUST utilize per-environment hooks (`buildStart`, `resolveId`, `load`) by inspecting `this.environment.name` instead of assuming a single global SSR compilation pass.

Plugins MUST utilize per-environment hooks (`buildStart`, `resolveId`, `load`) by inspecting `this.environment.name` instead of assuming a single global SSR compilation pass.

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

Dev server entry points MUST instantiate isolated `DevEnvironment` or `RunnableDevEnvironment` instances with dedicated runtime transports to prevent process-level global scope pollution.

Dev server entry points MUST instantiate isolated `DevEnvironment` or `RunnableDevEnvironment` instances with dedicated runtime transports to prevent process-level global scope pollution.

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 Environment API Multi-Runtime Module Execution Boundary critical for AI coding assistants?

Enforces strict isolation between client, worker/edge (e.g., Workerd), and Node.js execution runtimes when configuring Vite 6 multi-environment pipelines. Prevents cross-environment module graph leakage, improper resolve condition inheritance, and runtime host crash hazards caused by calling legacy SSR APIs in multi-target architectures. 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 (Leaking Node.js Built-ins and Shared Module Graphs into Edge Runtimes via Legacy Vite SSR APIs) 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.

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