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frontendcritical PriorityID: vite6-environment-api-runtime-sandboxing

Vite 6 Environment API Hybrid Runtime Sandboxing

Enforces strict module resolution, execution isolation, and runner virtualization across heterogeneous server runtimes (Workflows, Edge/workerd, Node.js) using the Vite 6 Environment API. Prevents runtime cross-contamination, global state bleed, and illegal platform-specific primitive leakage across concurrent SSR compilation targets.

Prohibited Anti-Pattern: Monolithic SSR resolution leaking Node-specific primitives into Edge/Workflow environments via legacy server.ssrLoadModule APIs

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---
description: Vite 6 Environment API Hybrid Runtime Sandboxing - Enforces strict module resolution, execution isolation, and runner virtualization across heterogeneous server runtimes (Workflows, Edge/workerd, Node.js) using the Vite 6 Environment API. Prevents runtime cross-contamination, global state bleed, and illegal platform-specific primitive leakage across concurrent SSR compilation targets.
globs: vite.config.ts, vite.config.*.ts, src/entry.*.ts, src/server/**/*.{ts,tsx}, server/**/*.{ts,js}
alwaysApply: true
verified_by: "agentrules.org"
license: "CC-BY-4.0"
source: "https://agentrules.org/rules/vite6-environment-api-runtime-sandboxing"
---

# Vite 6 Environment API Hybrid Runtime Sandboxing

> **Severity**: CRITICAL | **Category**: frontend
> **Anti-Pattern Warning**: Monolithic SSR resolution leaking Node-specific primitives into Edge/Workflow environments via legacy server.ssrLoadModule APIs

## System Constraints
You are a Principal Software Architect enforcing the Vite 6 Environment API standard for hybrid runtime SSR applications. You must enforce absolute execution and module resolution isolation across heterogeneous runtimes (such as Cloudflare workerd, Node.js, and background Workflows). Reject deprecated Vite 5 SSR APIs (such as `server.ssrLoadModule` and monolithic `server.moduleGraph`), verify discrete runtime conditions, and mandate dedicated DevEnvironment runner sandboxes.

## Strict Guidelines
- Engineers MUST ALWAYS define distinct runtime environments under `environments.<name>` in `vite.config.ts` with explicit `resolve.conditions` for each target (e.g., `['workerd', 'worker']` for edge, `['node']` for server).
- Engineers MUST NOT use deprecated Vite 5 SSR APIs, including `server.ssrLoadModule`, `server.ssrTransform`, or direct queries against `server.moduleGraph` when dealing with multi-environment systems.
- Code MUST execute target environment modules using `server.environments[envName].runner.import(entry)` instead of legacy global server runners.
- Services MUST isolate platform externals per environment using `environments.<name>.resolve.external` and `environments.<name>.resolve.noExternal` to prevent illegal runtime pollution (e.g., `node:fs` leaking into edge runtimes).
- Components and server entries NEVER cross-import platform-specific abstractions without wrapping them behind environment-specific entrypoints or resolution condition branches.

## Bad vs Good Implementations
### Multi-Environment SSR Configuration

#### Bad Antipattern (AI Common Hallucination)
> **Why it fails**: Configuring a single monolithic SSR target forces edge and background worker code to share the Node.js module graph and resolution conditions, causing runtime bleed (e.g., node:crypto or node:fs imported into workerd execution contexts) and relying on deprecated Vite 5 APIs.
```typescript
import { defineConfig } from 'vite';

// ANTI-PATTERN: Single monolithic SSR configuration attempting to serve
// both Node.js API tasks and Edge/Worker SSR. Leads to runtime pollution.
export default defineConfig({
  ssr: {
    target: 'node',
    noExternal: true,
  },
  server: {
    // Node primitives pollute the global scope for edge consumers
  },
});

// In server runner file:
// viteDevServer.ssrLoadModule('/src/entry.edge.ts'); // DEPRECATED: Uses default Node ssr environment
```

#### Production Standard (Correct)
> **Standard**: Declaring discrete environments under `environments` with targeted `resolve.conditions` ensures the edge module graph is completely separated from the Node.js module graph, preventing runtime pollution and executing sandboxed edge logic via Vite 6 DevEnvironment runners.
```typescript
import { defineConfig } from 'vite';

// PRODUCTION INVARIANT: Vite 6 Environment API with isolated runtime sandboxes
export default defineConfig({
  environments: {
    client: {
      consumer: 'client',
    },
    edge: {
      consumer: 'server',
      resolve: {
        conditions: ['workerd', 'worker', 'browser'],
        external: ['cloudflare:workers'],
        noExternal: true,
      },
      dev: {
        // Sandboxed execution isolated from Node.js globals
        createEnvironment(name, config) {
          return new (require('vite').DevEnvironment)(name, config);
        },
      },
    },
    node: {
      consumer: 'server',
      resolve: {
        conditions: ['node'],
        external: [/^node:/],
      },
    },
  },
});

// In server dispatcher:
// const edgeEnv = viteDevServer.environments.edge;
// const { render } = await edgeEnv.runner.import('/src/entry.edge.ts');
```
Recommended MCP Servers (mcp-serverlist.com)

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

Vite Runtime Inspector MCP
Inspects Vite 6 DevEnvironment module graphs, resolution trees, and runner memory contexts.
Recommended Agent Skills (askills.dev)

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

oxlint
High-performance linter used to assert runtime-specific import safety and prevent illegal node built-ins in edge code.
Architectural Specification & Invariant Rationale

Architectural Invariant Design: Vite 6 Environment API Hybrid Runtime Sandboxing

Vite 6 Environment API Hybrid Runtime Sandboxing defines an industrial-grade behavioral standard for frontend engineering. Enforces strict module resolution, execution isolation, and runner virtualization across heterogeneous server runtimes (Workflows, Edge/workerd, Node.js) using the Vite 6 Environment API. Prevents runtime cross-contamination, global state bleed, and illegal platform-specific primitive leakage across concurrent SSR compilation targets. 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 resolution leaking Node-specific primitives into Edge/Workflow environments via legacy server.ssrLoadModule 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 DriftMonolithic SSR resolution leaking Node-specific primitives into Edge/Workflow environments via legacy server.ssrLoadModule 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 define distinct runtime environments under `environments.<name>` in `vite.config.ts` with explicit `resolve.conditions` for each target (e.g., `['workerd', 'worker']` for edge, `['node']` for server).

Engineers MUST ALWAYS define distinct runtime environments under `environments.<name>` in `vite.config.ts` with explicit `resolve.conditions` for each target (e.g., `['workerd', 'worker']` for edge, `['node']` for server).

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 use deprecated Vite 5 SSR APIs, including `server.ssrLoadModule`, `server.ssrTransform`, or direct queries against `server.moduleGraph` when dealing with multi-environment systems.

Engineers MUST NOT use deprecated Vite 5 SSR APIs, including `server.ssrLoadModule`, `server.ssrTransform`, or direct queries against `server.moduleGraph` when dealing with multi-environment systems.

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 MUST execute target environment modules using `server.environments[envName].runner.import(entry)` instead of legacy global server runners.

Code MUST execute target environment modules using `server.environments[envName].runner.import(entry)` instead of legacy global server runners.

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 platform externals per environment using `environments.<name>.resolve.external` and `environments.<name>.resolve.noExternal` to prevent illegal runtime pollution (e.g., `node

Services MUST isolate platform externals per environment using `environments.<name>.resolve.external` and `environments.<name>.resolve.noExternal` to prevent illegal runtime pollution (e.g., `node:fs` leaking into edge runtimes).

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 and server entries NEVER cross-import platform-specific abstractions without wrapping them behind environment-specific entrypoints or resolution condition branches.

Components and server entries NEVER cross-import platform-specific abstractions without wrapping them behind environment-specific entrypoints or resolution condition branches.

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 Hybrid Runtime Sandboxing critical for AI coding assistants?

Enforces strict module resolution, execution isolation, and runner virtualization across heterogeneous server runtimes (Workflows, Edge/workerd, Node.js) using the Vite 6 Environment API. Prevents runtime cross-contamination, global state bleed, and illegal platform-specific primitive leakage across concurrent SSR compilation targets. 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 resolution leaking Node-specific primitives into Edge/Workflow environments via legacy server.ssrLoadModule 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.

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