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frontendcritical PriorityID: vite6-environment-api-ssr-sandboxing-vite-6-environme-144

Vite 6 Environment API Heterogeneous SSR Sandboxing Invariant

Enforces absolute module graph separation and runtime boundary isolation across client, Node SSR, and edge runtimes using Vite 6's Environment API. Eliminates leakage of server-only primitives, Node.js native built-ins, and secure credentials into client bundle targets or client HMR channels. Mandates environment-conditioned plugin execution and strict per-environment resolve conditions.

Prohibited Anti-Pattern: Cross-Environment Module Graph Contamination and Server Primitive Leakage in Vite 6 SSR

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---
description: Vite 6 Environment API Heterogeneous SSR Sandboxing Invariant - Enforces absolute module graph separation and runtime boundary isolation across client, Node SSR, and edge runtimes using Vite 6's Environment API. Eliminates leakage of server-only primitives, Node.js native built-ins, and secure credentials into client bundle targets or client HMR channels. Mandates environment-conditioned plugin execution and strict per-environment resolve conditions.
globs: vite.config.{ts,js,mjs}, src/**/*.{ts,tsx,js,jsx}, server/**/*.{ts,js}
alwaysApply: true
verified_by: "agentrules.org"
license: "CC-BY-4.0"
source: "https://agentrules.org/rules/vite6-environment-api-ssr-sandboxing-vite-6-environme-144"
---

# Vite 6 Environment API Heterogeneous SSR Sandboxing Invariant

> **Severity**: CRITICAL | **Category**: frontend
> **Anti-Pattern Warning**: Cross-Environment Module Graph Contamination and Server Primitive Leakage in Vite 6 SSR

## System Constraints
You are a Principal Software Architect enforcing Vite 6 Environment API Heterogeneous SSR Sandboxing Invariants. You must ensure that client, Node SSR, and edge module runtimes remain strictly isolated during both dev HMR and multi-environment production builds. Server-only symbols, native node modules, and backend secret bindings must never leak into client environments.

## Strict Guidelines
- Engineers MUST ALWAYS configure distinct environment targets under Vite 6 `environments` (e.g., `environments.client`, `environments.ssr`, `environments.edge`) with targeted `resolve.conditions` and `consumer` attributes.
- Engineers MUST NOT access global or shared module graphs via legacy `server.moduleGraph`; all module graph queries and invalidations MUST target `this.environment.moduleGraph` or `server.environments[name].moduleGraph`.
- Plugin hooks that manipulate imports or transforms MUST check `this.environment.name` before executing runtime-specific transformations or injecting environment-specific polyfills.
- Code MUST NEVER import server-only primitives (e.g., `node:fs`, `node:crypto`, database drivers, or private server config) into modules accessible within the `client` environment graph.
- HMR payloads MUST be dispatched through `this.environment.hot.send` to prevent cross-runtime HMR event collisions and accidental client evaluation of server mutations.
- Build orchestrations MUST use `builder.buildApp()` with per-environment runner dispatch rather than serial invocation of legacy bundle hooks.

## Bad vs Good Implementations
### Vite 6 Environment API Configuration and Plugin Sandboxing

#### Bad Antipattern (AI Common Hallucination)
> **Why it fails**: The plugin executes unconstrained transforms without checking `this.environment.name`, injecting sensitive server files into client bundles. Additionally, it references legacy `server.moduleGraph`, breaking Vite 6 multi-environment isolation and corrupting cross-environment HMR states.
```typescript
import { defineConfig } from 'vite';
import fs from 'node:fs';

export default defineConfig({
  ssr: {
    noExternal: ['shared-lib'],
  },
  plugins: [{
    name: 'leak-server-context',
    transform(code, id) {
      // CRITICAL FLAW: Ignores Vite 6 Environment API context;
      // transforms all modules identically across client and SSR.
      // Leaks server filesystem paths directly into client assets.
      if (id.includes('config-provider')) {
        const serverSecret = fs.readFileSync('/etc/secrets/config.json', 'utf8');
        return `export const config = ${serverSecret};`;
      }
      return code;
    },
    handleHotUpdate(ctx) {
      // CRITICAL FLAW: Global invalidation across all module graphs
      ctx.server.moduleGraph.invalidateModule(ctx.server.moduleGraph.getModuleById(ctx.file)!);
    }
  }]
});
```

#### Production Standard (Correct)
> **Standard**: Declares explicit heterogeneous runtimes (`client`, `ssr`, `edge`) under `environments` with targeted export conditions. Plugins inspect `this.environment.name` to prevent secret leakage, and HMR updates are isolated to `this.environment.moduleGraph` and `this.environment.hot`.
```typescript
import { defineConfig, type Plugin } from 'vite';

function isolatedEnvironmentPlugin(): Plugin {
  return {
    name: 'isolated-environment-guard',
    // Enforce per-environment isolation within Vite 6 hooks
    transform(code, id) {
      if (this.environment.name === 'client' && id.includes('config-provider')) {
        // Client-safe stubbing: Server primitives must never cross this boundary
        return `export const config = { publicApiUrl: import.meta.env.VITE_PUBLIC_API_URL };`;
      }
      if (this.environment.name === 'ssr' && id.includes('config-provider')) {
        return `export const config = { privateSecret: process.env.SERVER_SECRET };`;
      }
      return code;
    },
    hotUpdate({ modules, type, timestamp }) {
      // Environment-isolated HMR invalidation
      const envGraph = this.environment.moduleGraph;
      for (const mod of modules) {
        envGraph.invalidateModule(mod);
      }
      this.environment.hot.send({
        type: 'custom',
        event: `${this.environment.name}:update`,
        data: { timestamp }
      });
    }
  };
}

export default defineConfig({
  environments: {
    client: {
      build: {
        outDir: 'dist/client',
        sourcemap: false
      },
      resolve: {
        conditions: ['browser', 'module']
      }
    },
    ssr: {
      build: {
        outDir: 'dist/server',
        ssr: true
      },
      resolve: {
        conditions: ['node', 'import']
      }
    },
    edge: {
      resolve: {
        conditions: ['worker', 'edge-light']
      }
    }
  },
  plugins: [isolatedEnvironmentPlugin()]
});
```
Recommended MCP Servers (mcp-serverlist.com)

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

Vite Module Graph Inspector MCP
Inspects Vite 6 environment module graphs to detect cross-runtime leakage and resolve conditions.
Recommended Agent Skills (askills.dev)

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

Vite Environment Graph Audit CLI
Validates that client bundles contain zero unresolved server-side imports and that environment conditions are cleanly isolated.
Architectural Specification & Invariant Rationale

Architectural Invariant Design: Vite 6 Environment API Heterogeneous SSR Sandboxing Invariant

Vite 6 Environment API Heterogeneous SSR Sandboxing Invariant defines an industrial-grade behavioral standard for frontend engineering. Enforces absolute module graph separation and runtime boundary isolation across client, Node SSR, and edge runtimes using Vite 6's Environment API. Eliminates leakage of server-only primitives, Node.js native built-ins, and secure credentials into client bundle targets or client HMR channels. Mandates environment-conditioned plugin execution and strict per-environment resolve conditions. 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: Cross-Environment Module Graph Contamination and Server Primitive Leakage in Vite 6 SSR 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 DriftCross-Environment Module Graph Contamination and Server Primitive Leakage in Vite 6 SSRCritical
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 distinct environment targets under Vite 6 `environments` (e.g., `environments.client`, `environments.ssr`, `environments.edge`) with targeted `resolve.conditions` and `consumer` attributes.

Engineers MUST ALWAYS configure distinct environment targets under Vite 6 `environments` (e.g., `environments.client`, `environments.ssr`, `environments.edge`) with targeted `resolve.conditions` and `consumer` attributes.

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 access global or shared module graphs via legacy `server.moduleGraph`

Engineers MUST NOT access global or shared module graphs via legacy `server.moduleGraph`; all module graph queries and invalidations MUST target `this.environment.moduleGraph` or `server.environments[name].moduleGraph`.

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

Plugin hooks that manipulate imports or transforms MUST check `this.environment.name` before executing runtime-specific transformations or injecting environment-specific polyfills.

Plugin hooks that manipulate imports or transforms MUST check `this.environment.name` before executing runtime-specific transformations or injecting environment-specific polyfills.

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 MUST NEVER import server-only primitives (e.g., `node

Code MUST NEVER import server-only primitives (e.g., `node:fs`, `node:crypto`, database drivers, or private server config) into modules accessible within the `client` environment graph.

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

HMR payloads MUST be dispatched through `this.environment.hot.send` to prevent cross-runtime HMR event collisions and accidental client evaluation of server mutations.

HMR payloads MUST be dispatched through `this.environment.hot.send` to prevent cross-runtime HMR event collisions and accidental client evaluation of server 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.
6

Build orchestrations MUST use `builder.buildApp()` with per-environment runner dispatch rather than serial invocation of legacy bundle hooks.

Build orchestrations MUST use `builder.buildApp()` with per-environment runner dispatch rather than serial invocation of legacy bundle hooks.

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 Heterogeneous SSR Sandboxing Invariant critical for AI coding assistants?

Enforces absolute module graph separation and runtime boundary isolation across client, Node SSR, and edge runtimes using Vite 6's Environment API. Eliminates leakage of server-only primitives, Node.js native built-ins, and secure credentials into client bundle targets or client HMR channels. Mandates environment-conditioned plugin execution and strict per-environment resolve conditions. 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 (Cross-Environment Module Graph Contamination and Server Primitive Leakage in Vite 6 SSR) 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.

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