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frontendcritical PriorityID: vite-6-environment-api-multi-runtime-isolation-vite-6-environme-583

Vite 6 Environment API: Multi-Runtime Context & Memory Isolation Invariants

Enforces strict runtime boundary separation and deterministic module evaluation across divergent execution targets (Browser DOM, Node.js SSR, Edge/workerd) using the Vite 6 Environment API. Prevents cross-environment state pollution, invalidated cross-runtime module graph caching, and catastrophic CJS/ESM interop leaks in hybrid compilation topologies.

Prohibited Anti-Pattern: Global Plugin State Sharing and Legacy SSR Pipeline Coupling Across Heterogeneous Runtimes

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---
description: Vite 6 Environment API: Multi-Runtime Context & Memory Isolation Invariants - Enforces strict runtime boundary separation and deterministic module evaluation across divergent execution targets (Browser DOM, Node.js SSR, Edge/workerd) using the Vite 6 Environment API. Prevents cross-environment state pollution, invalidated cross-runtime module graph caching, and catastrophic CJS/ESM interop leaks in hybrid compilation topologies.
globs: vite.config.{ts,js,mjs}, plugins/**/*.{ts,js}, src/server/**/*.{ts,js}, src/entry-*.{ts,tsx,js,jsx}
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-583"
---

# Vite 6 Environment API: Multi-Runtime Context & Memory Isolation Invariants

> **Severity**: CRITICAL | **Category**: frontend
> **Anti-Pattern Warning**: Global Plugin State Sharing and Legacy SSR Pipeline Coupling Across Heterogeneous Runtimes

## System Constraints
You are a Principal Software Architect enforcing deterministic module execution and memory isolation under Vite 6 Environment API specifications. You must eliminate all shared cross-runtime singletons, prohibit deprecated Vite 5 SSR APIs, mandate environment-scoped plugin lifecycles via `this.environment`, and ensure target runtimes (Node.js vs Edge/workerd) maintain completely isolated module runner execution contexts.

## Strict Guidelines
- Engineers MUST ALWAYS access runtime-specific compilation context via `this.environment` inside Vite plugin hooks (`resolveId`, `load`, `transform`, `buildStart`).
- Engineers MUST NOT maintain shared, process-wide global mutable state (e.g., top-level `Map`, `Set`, or objects) in Vite plugins across divergent environments; all state MUST be partitioned by `this.environment.name` or stored via `WeakMap<DevEnvironment, T>`.
- Engineers MUST NOT invoke deprecated Vite 4/5 SSR APIs including `server.ssrLoadModule`, `server.ssrTransform`, or `server.ssrFixStacktrace`; execution MUST utilize `server.environments[name].runner.import` or `DevEnvironment.loadModule`.
- Custom environments (e.g., edge, workerd, node) defined in `vite.config.ts` MUST configure explicit `resolve.conditions`, `resolve.external`, and independent `DevEnvironment` options to prevent accidental Node.js CJS leakage into edge targets.
- Module runners MUST instantiate dedicated communication channels and execution contexts per environment; code executing inside edge runtimes MUST NEVER reference Node.js global singletons like `process.cwd()` without environment polyfill mapping.

## Bad vs Good Implementations
### Cross-Runtime Environment Cache & Module Runner Isolation

#### Bad Antipattern (AI Common Hallucination)
> **Why it fails**: The plugin relies on a process-wide `transformCache` that fails to separate modules by environment (e.g. an edge worker receives code compiled for Node.js). It uses deprecated `this.ssr` and `server.ssrLoadModule`, breaking execution when targeting non-Node runtimes like workerd or Deno.
```typescript
import { Plugin, ViteDevServer } from 'vite';

// ANTI-PATTERN: Global plugin cache shared across both 'ssr' (Node) and 'edge' environments.
// Causes cross-runtime module resolution bleeding and memory leaks.
const transformCache = new Map<string, string>();

export function brokenHybridPlugin(): Plugin {
  let server: ViteDevServer;
  return {
    name: 'broken-hybrid-plugin',
    configureServer(devServer) {
      server = devServer;
    },
    transform(code, id) {
      if (transformCache.has(id)) {
        return transformCache.get(id);
      }
      // Legacy SSR check: cannot differentiate between Node.js SSR and Edge worker runtime
      const isSSR = this.ssr;
      const transformed = code.replace(/__RUNTIME_TARGET__/g, isSSR ? 'node' : 'client');
      transformCache.set(id, transformed);
      return transformed;
    },
    async handleHotUpdate({ file }) {
      // Deprecated API: forces Node.js VM evaluation even if the target is Edge/workerd
      await server.ssrLoadModule(file);
    }
  };
}
```

#### Production Standard (Correct)
> **Standard**: Utilizes Vite 6 `DevEnvironment` metadata (`this.environment`) to guarantee zero cache bleeding across compilation runtimes. Replaces deprecated SSR primitives with `RunnableDevEnvironment.runner.import` and manages per-environment lifecycle states using weak memory references.
```typescript
import { Plugin, DevEnvironment, RunnableDevEnvironment } from 'vite';

// PRODUCTION FIX: Scoped environment caching using WeakMap keyed by DevEnvironment instance
const envTransformCache = new WeakMap<DevEnvironment, Map<string, string>>();

export function isolatedHybridPlugin(): Plugin {
  return {
    name: 'isolated-hybrid-plugin',
    // Enforce environment isolation in hooks
    transform(code, id) {
      const env = this.environment;
      if (!env) {
        throw new Error(`[isolated-hybrid-plugin] Transformation attempted outside DevEnvironment lifecycle for module: ${id}`);
      }

      let cache = envTransformCache.get(env);
      if (!cache) {
        cache = new Map();
        envTransformCache.set(env, cache);
      }

      if (cache.has(id)) {
        return cache.get(id);
      }

      // Explicitly distinguish between runtimes (e.g., 'client', 'ssr', 'edge')
      const runtimeName = env.name; 
      const transformed = code.replace(/__RUNTIME_TARGET__/g, runtimeName);
      cache.set(id, transformed);
      return transformed;
    },
    async handleHotUpdate({ file, server }) {
      // Dispatch reload/invalidation per isolated DevEnvironment runner
      for (const [name, environment] of Object.entries(server.environments)) {
        if (environment instanceof RunnableDevEnvironment) {
          const mod = environment.moduleGraph.getModuleById(file);
          if (mod) {
            environment.moduleGraph.invalidateModule(mod);
            await environment.runner.import(file);
          }
        }
      }
    }
  };
}
```
Recommended MCP Servers (mcp-serverlist.com)

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

Vite Runtime Inspector MCP
Monitors Vite 6 compilation graphs and environment runners across active compilation processes.
Recommended Agent Skills (askills.dev)

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

Verify Vite 6 Environment Manifest
Audits `vite.config.ts` to verify strict environment isolation, runtime conditions, and exclusion of deprecated SSR calls.
Architectural Specification & Invariant Rationale

Architectural Invariant Design: Vite 6 Environment API: Multi-Runtime Context & Memory Isolation Invariants

Vite 6 Environment API: Multi-Runtime Context & Memory Isolation Invariants defines an industrial-grade behavioral standard for frontend engineering. Enforces strict runtime boundary separation and deterministic module evaluation across divergent execution targets (Browser DOM, Node.js SSR, Edge/workerd) using the Vite 6 Environment API. Prevents cross-environment state pollution, invalidated cross-runtime module graph caching, and catastrophic CJS/ESM interop leaks in hybrid compilation topologies. 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: Global Plugin State Sharing and Legacy SSR Pipeline Coupling Across Heterogeneous Runtimes 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 DriftGlobal Plugin State Sharing and Legacy SSR Pipeline Coupling Across Heterogeneous RuntimesCritical
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 access runtime-specific compilation context via `this.environment` inside Vite plugin hooks (`resolveId`, `load`, `transform`, `buildStart`).

Engineers MUST ALWAYS access runtime-specific compilation context via `this.environment` inside Vite plugin hooks (`resolveId`, `load`, `transform`, `buildStart`).

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 maintain shared, process-wide global mutable state (e.g., top-level `Map`, `Set`, or objects) in Vite plugins across divergent environments

Engineers MUST NOT maintain shared, process-wide global mutable state (e.g., top-level `Map`, `Set`, or objects) in Vite plugins across divergent environments; all state MUST be partitioned by `this.environment.name` or stored via `WeakMap<DevEnvironment, T>`.

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

Engineers MUST NOT invoke deprecated Vite 4/5 SSR APIs including `server.ssrLoadModule`, `server.ssrTransform`, or `server.ssrFixStacktrace`

Engineers MUST NOT invoke deprecated Vite 4/5 SSR APIs including `server.ssrLoadModule`, `server.ssrTransform`, or `server.ssrFixStacktrace`; execution MUST utilize `server.environments[name].runner.import` or `DevEnvironment.loadModule`.

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

Custom environments (e.g., edge, workerd, node) defined in `vite.config.ts` MUST configure explicit `resolve.conditions`, `resolve.external`, and independent `DevEnvironment` options to prevent accidental Node.js CJS leakage into edge targets.

Custom environments (e.g., edge, workerd, node) defined in `vite.config.ts` MUST configure explicit `resolve.conditions`, `resolve.external`, and independent `DevEnvironment` options to prevent accidental Node.js CJS leakage into edge 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.
5

Module runners MUST instantiate dedicated communication channels and execution contexts per environment

Module runners MUST instantiate dedicated communication channels and execution contexts per environment; code executing inside edge runtimes MUST NEVER reference Node.js global singletons like `process.cwd()` without environment polyfill mapping.

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 Context & Memory Isolation Invariants critical for AI coding assistants?

Enforces strict runtime boundary separation and deterministic module evaluation across divergent execution targets (Browser DOM, Node.js SSR, Edge/workerd) using the Vite 6 Environment API. Prevents cross-environment state pollution, invalidated cross-runtime module graph caching, and catastrophic CJS/ESM interop leaks in hybrid compilation topologies. 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 (Global Plugin State Sharing and Legacy SSR Pipeline Coupling Across Heterogeneous Runtimes) 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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