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frontendcritical PriorityID: vite-6-environment-api-module-graph-isolation

Vite 6 Environment API Module Graph and Runtime Isolation Standard

Enforces strict isolation across Vite 6 environments (client, ssr, edge, and worker) via discrete module graphs, distinct resolution conditions, and environment-scoped plugin hooks. Eliminates cross-runtime contamination, Node polyfill leakage into browser bundles, and module cache poisoning in isomorphic enterprise applications.

Prohibited Anti-Pattern: Monolithic Module Graph Resolution and Ambient Node Polyfill Leakage Across Isomorphic Boundaries

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---
description: Vite 6 Environment API Module Graph and Runtime Isolation Standard - Enforces strict isolation across Vite 6 environments (client, ssr, edge, and worker) via discrete module graphs, distinct resolution conditions, and environment-scoped plugin hooks. Eliminates cross-runtime contamination, Node polyfill leakage into browser bundles, and module cache poisoning in isomorphic enterprise applications.
globs: vite.config.{ts,js,mjs}, src/**/*.{ts,tsx,js,jsx}
alwaysApply: true
verified_by: "agentrules.org"
license: "CC-BY-4.0"
source: "https://agentrules.org/rules/vite-6-environment-api-module-graph-isolation"
---

# Vite 6 Environment API Module Graph and Runtime Isolation Standard

> **Severity**: CRITICAL | **Category**: frontend
> **Anti-Pattern Warning**: Monolithic Module Graph Resolution and Ambient Node Polyfill Leakage Across Isomorphic Boundaries

## System Constraints
You are a Principal Software Architect enforcing Vite 6 Environment API architectural isolation. Mandate isolated module graphs across runtime targets, scoped plugin transforms, distinct resolution conditions, and zero cross-runtime Node polyfill leakage.

## Strict Guidelines
- Engineers MUST ALWAYS configure discrete runtime contexts using Vite 6's top-level `environments` configuration block (e.g., `environments.client`, `environments.ssr`, `environments.worker`) instead of relying on legacy monolithic root-level configurations.
- Engineers MUST NOT share un-scoped Vite plugins across environments when those plugins mutate module ASTs, inject runtime shims, or resolve target-specific globals.
- Plugins MUST verify `this.environment.name` in lifecycle hooks (`resolveId`, `load`, `transform`) or declare `applyToEnvironment(environment)` to guarantee transform segregation.
- Engineers MUST declare explicit export conditions per environment via `resolve.conditions` (e.g., `['browser']` for client vs `['node']` for SSR) to prevent Dual Package Hazard and unintended Node builtin resolution in browser bundles.
- SSR runner implementations MUST utilize Vite 6 `createViteRuntime` with dedicated environment runners rather than deprecated `viteDevServer.ssrLoadModule`.
- Components and shared isomorphic libraries MUST NEVER import environment-specific singletons directly; target-specific dependencies must be abstracted behind inversion-of-control tokens or conditional module resolutions.

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

#### Bad Antipattern (AI Common Hallucination)
> **Why it fails**: Applying global node polyfills and shared aliases at the root configuration pollutes the browser module graph with heavy node shims, risks dual-package hazards, and breaks isolated module evaluation across isomorphic runtimes.
```typescript
import { defineConfig } from 'vite';
import nodePolyfills from 'vite-plugin-node-polyfills';

// ANTI-PATTERN: Monolithic configuration polluting client graph with node fallbacks
// and using legacy SSR options that mix module resolution.
export default defineConfig({
  plugins: [
    nodePolyfills({ globals: { Buffer: true, process: true } }) // Leaks into all builds
  ],
  ssr: {
    noExternal: ['shared-lib'], // Ambiguous resolution across targets
  },
  resolve: {
    alias: {
      stream: 'stream-browserify',
      buffer: 'buffer'
    }
  },
  build: {
    ssr: false
  }
});
```

#### Production Standard (Correct)
> **Standard**: Defines explicit `environments` for client and SSR targets. Each environment maintains its own module graph, condition flags, and external boundaries, ensuring browser bundles never bundle Node-specific modules or extraneous shims.
```typescript
import { defineConfig } from 'vite';

// PRODUCTION INVARIANT: Isolated Vite 6 Environment API graph resolution
export default defineConfig({
  environments: {
    client: {
      build: {
        outDir: 'dist/client',
        rollupOptions: {
          input: '/src/entry-client.tsx'
        }
      },
      resolve: {
        conditions: ['browser', 'import', 'module'],
        noExternal: false
      }
    },
    ssr: {
      build: {
        outDir: 'dist/server',
        rollupOptions: {
          input: '/src/entry-server.tsx'
        }
      },
      resolve: {
        conditions: ['node', 'import', 'module'],
        external: ['stream', 'buffer', 'crypto', 'node:*']
      }
    }
  },
  builder: {
    async buildApp(builder) {
      await builder.build(builder.environments.client);
      await builder.build(builder.environments.ssr);
    }
  }
});
```

### Environment-Scoped Plugin Lifecycle Hook Guard

#### Bad Antipattern (AI Common Hallucination)
> **Why it fails**: The transform hook executes across all environment graphs without checking `this.environment`, injecting server store dependencies into client and worker builds and causing fatal runtime bundle errors.
```typescript
import type { Plugin } from 'vite';

// ANTI-PATTERN: Indiscriminate transform running on all module graphs
export function isomorphicInjectPlugin(): Plugin {
  return {
    name: 'inject-runtime-context',
    transform(code, id) {
      if (id.endsWith('.ts')) {
        // Injects Node global process check unconditionally across client, worker, and SSR
        return `import { runtimeStore } from '@/server/store';\n${code}`;
      }
      return code;
    }
  };
}
```

#### Production Standard (Correct)
> **Standard**: Uses `applyToEnvironment` and validates `this.environment.name` directly in hooks. Guarantees server-only AST manipulation and imports are strictly confined to the SSR module graph.
```typescript
import type { Plugin, Environment } from 'vite';

// PRODUCTION INVARIANT: Explicit environment verification inside plugin hooks
export function isomorphicInjectPlugin(): Plugin {
  return {
    name: 'inject-runtime-context',
    applyToEnvironment(environment: Environment) {
      // Only apply this plugin instance to the SSR environment
      return environment.name === 'ssr';
    },
    transform(code, id) {
      // Guardrail invariant ensures this.environment.name is deterministically 'ssr'
      if (this.environment.name !== 'ssr') {
        return null;
      }
      if (id.endsWith('.ts') && !id.includes('node_modules')) {
        return {
          code: `import { runtimeStore } from '@/server/store';\n${code}`,
          map: null
        };
      }
      return null;
    }
  };
}
```
Recommended MCP Servers (mcp-serverlist.com)

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

Vite Module Graph Inspector MCP
Analyzes Vite 6 DevEnvironment module graphs to detect cross-environment module leakage and circular external dependencies.
Recommended Agent Skills (askills.dev)

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

Vite Bundle Analyzer CLI
Verifies that production client bundles contain zero Node.js core polyfills and respect isolated environment boundaries.
Architectural Specification & Invariant Rationale

Architectural Invariant Design: Vite 6 Environment API Module Graph and Runtime Isolation Standard

Vite 6 Environment API Module Graph and Runtime Isolation Standard defines an industrial-grade behavioral standard for frontend engineering. Enforces strict isolation across Vite 6 environments (client, ssr, edge, and worker) via discrete module graphs, distinct resolution conditions, and environment-scoped plugin hooks. Eliminates cross-runtime contamination, Node polyfill leakage into browser bundles, and module cache poisoning in isomorphic enterprise applications. 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 Module Graph Resolution and Ambient Node Polyfill Leakage Across Isomorphic Boundaries 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 Module Graph Resolution and Ambient Node Polyfill Leakage Across Isomorphic BoundariesCritical
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 runtime contexts using Vite 6's top-level `environments` configuration block (e.g., `environments.client`, `environments.ssr`, `environments.worker`) instead of relying on legacy monolithic root-level configurations.

Engineers MUST ALWAYS configure discrete runtime contexts using Vite 6's top-level `environments` configuration block (e.g., `environments.client`, `environments.ssr`, `environments.worker`) instead of relying on legacy monolithic root-level configurations.

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 share un-scoped Vite plugins across environments when those plugins mutate module ASTs, inject runtime shims, or resolve target-specific globals.

Engineers MUST NOT share un-scoped Vite plugins across environments when those plugins mutate module ASTs, inject runtime shims, or resolve target-specific globals.

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

Plugins MUST verify `this.environment.name` in lifecycle hooks (`resolveId`, `load`, `transform`) or declare `applyToEnvironment(environment)` to guarantee transform segregation.

Plugins MUST verify `this.environment.name` in lifecycle hooks (`resolveId`, `load`, `transform`) or declare `applyToEnvironment(environment)` to guarantee transform segregation.

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

Engineers MUST declare explicit export conditions per environment via `resolve.conditions` (e.g., `['browser']` for client vs `['node']` for SSR) to prevent Dual Package Hazard and unintended Node builtin resolution in browser bundles.

Engineers MUST declare explicit export conditions per environment via `resolve.conditions` (e.g., `['browser']` for client vs `['node']` for SSR) to prevent Dual Package Hazard and unintended Node builtin resolution in browser bundles.

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

SSR runner implementations MUST utilize Vite 6 `createViteRuntime` with dedicated environment runners rather than deprecated `viteDevServer.ssrLoadModule`.

SSR runner implementations MUST utilize Vite 6 `createViteRuntime` with dedicated environment runners rather than deprecated `viteDevServer.ssrLoadModule`.

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

Components and shared isomorphic libraries MUST NEVER import environment-specific singletons directly

Components and shared isomorphic libraries MUST NEVER import environment-specific singletons directly; target-specific dependencies must be abstracted behind inversion-of-control tokens or conditional module resolutions.

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 Module Graph and Runtime Isolation Standard critical for AI coding assistants?

Enforces strict isolation across Vite 6 environments (client, ssr, edge, and worker) via discrete module graphs, distinct resolution conditions, and environment-scoped plugin hooks. Eliminates cross-runtime contamination, Node polyfill leakage into browser bundles, and module cache poisoning in isomorphic enterprise applications. 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 Module Graph Resolution and Ambient Node Polyfill Leakage Across Isomorphic Boundaries) 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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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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