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frontendcritical PriorityID: vite6-environment-api-secret-fence

Vite 6 Multi-Runtime Environment API Secret Fence Standard

Enforces strict compile-time boundary isolation across Vite 6 Environment API runtimes (Client, Node SSR, Edge). Prevents server-only credentials, platform bindings, and non-distributable server module graphs from leaking into client-targeted compilation units.

Prohibited Anti-Pattern: Cross-Runtime Module Graph Contamination Leaking Server Secrets into Client Artifacts

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---
description: Vite 6 Multi-Runtime Environment API Secret Fence Standard - Enforces strict compile-time boundary isolation across Vite 6 Environment API runtimes (Client, Node SSR, Edge). Prevents server-only credentials, platform bindings, and non-distributable server module graphs from leaking into client-targeted compilation units.
globs: vite.config.ts, vite.config.*.ts, src/**/*.{ts,tsx}, server/**/*.{ts,tsx}
alwaysApply: true
verified_by: "agentrules.org"
license: "CC-BY-4.0"
source: "https://agentrules.org/rules/vite6-environment-api-secret-fence"
---

# Vite 6 Multi-Runtime Environment API Secret Fence Standard

> **Severity**: CRITICAL | **Category**: frontend
> **Anti-Pattern Warning**: Cross-Runtime Module Graph Contamination Leaking Server Secrets into Client Artifacts

## System Constraints
You are a Principal Architect enforcing the Vite 6 Environment API Multi-Runtime Secret-Fence Standard. Vite 6 enables distinct module graphs per runtime target (e.g., client, ssr, edge). You must guarantee zero leakage of server-only environment variables, native node bindings, and private backend credentials into client builds by strictly configuring environment-scoped module resolutions, runtime fences, and compile-time validation assertions.

## Strict Guidelines
- Engineers MUST ALWAYS isolate runtime target configurations inside Vite 6 `environments` blocks (`client`, `ssr`, `edge`) instead of using monolithic top-level flags.
- Engineers MUST NOT expose server environment variables via global `define` configs; secrets MUST only be bound within dedicated server runtime environments.
- Vite plugins MUST ALWAYS query `this.environment.name` in transform/resolve hooks before operating on module graphs to prevent injecting server logic into the `client` environment.
- Engineers MUST configure an explicit compile-time fence plugin that rejects imports of `$env/server/*`, `server-only`, or sensitive credential registries whenever `this.environment.name === 'client'`.
- Modules containing private server logic MUST specify subpath exports with runtime conditions or fail-safe barriers preventing import from client-facing graphs.

## Bad vs Good Implementations
### Vite 6 Environment Configuration with Compile-Time Secret Fence

#### Bad Antipattern (AI Common Hallucination)
> **Why it fails**: Top-level `define` applies text replacement unconditionally across both client and server module graphs. Any accidental reference in frontend components embeds unencrypted production database and Stripe secrets directly into browser-shipped JavaScript bundles.
```typescript
import { defineConfig } from 'vite';
import dotenv from 'dotenv';

dotenv.config();

// VULNERABLE: Global define exposes backend DB credentials to ALL module graphs
export default defineConfig({
  define: {
    'process.env.DATABASE_URL': JSON.stringify(process.env.DATABASE_URL),
    'process.env.STRIPE_SECRET_KEY': JSON.stringify(process.env.STRIPE_SECRET_KEY)
  },
  build: {
    ssr: true
  }
});
```

#### Production Standard (Correct)
> **Standard**: Leverages Vite 6 Environment API to isolate environments and builds. Attaches secrets exclusively to the 'ssr' environment and introduces an active resolve-fence plugin checking `this.environment.name === 'client'` to abort compilation if server modules are imported into the client graph.
```typescript
import { defineConfig, type Plugin } from 'vite';

function clientSecretFencePlugin(): Plugin {
  const FORBIDDEN_SERVER_MODULES = [/^server-only$/, /\.server(\.[jt]sx?)?$/, /\/server\//];
  return {
    name: 'vite-plugin-client-secret-fence',
    resolveId(source) {
      if (this.environment.name === 'client') {
        const isForbidden = FORBIDDEN_SERVER_MODULES.some((regex) => regex.test(source));
        if (isForbidden) {
          throw new Error(
            `[Secret-Fence Violation]: Unauthorized import of server module '${source}' within Vite environment '${this.environment.name}'.`
          );
        }
      }
      return null;
    }
  };
}

export default defineConfig({
  plugins: [clientSecretFencePlugin()],
  environments: {
    client: {
      build: {
        outDir: 'dist/client'
      }
    },
    ssr: {
      build: {
        outDir: 'dist/server'
      },
      define: {
        // Secure: Explicitly bounded exclusively to the SSR environment
        'process.env.DATABASE_URL': JSON.stringify(process.env.DATABASE_URL)
      }
    }
  }
});
```
Recommended MCP Servers (mcp-serverlist.com)

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

Fetch MCP
Validates upstream Vite 6 release notes, migration guides, and Environment API changes.
Recommended Agent Skills (askills.dev)

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

AST-Grep CLI
Performs structural search on vite.config.ts and source files to catch leaked server imports in frontend files.
Architectural Specification & Invariant Rationale

Architectural Invariant Design: Vite 6 Multi-Runtime Environment API Secret Fence Standard

Vite 6 Multi-Runtime Environment API Secret Fence Standard defines an industrial-grade behavioral standard for frontend engineering. Enforces strict compile-time boundary isolation across Vite 6 Environment API runtimes (Client, Node SSR, Edge). Prevents server-only credentials, platform bindings, and non-distributable server module graphs from leaking into client-targeted compilation units. 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-Runtime Module Graph Contamination Leaking Server Secrets into Client Artifacts 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-Runtime Module Graph Contamination Leaking Server Secrets into Client ArtifactsCritical
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 isolate runtime target configurations inside Vite 6 `environments` blocks (`client`, `ssr`, `edge`) instead of using monolithic top-level flags.

Engineers MUST ALWAYS isolate runtime target configurations inside Vite 6 `environments` blocks (`client`, `ssr`, `edge`) instead of using monolithic top-level flags.

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 expose server environment variables via global `define` configs

Engineers MUST NOT expose server environment variables via global `define` configs; secrets MUST only be bound within dedicated server runtime environments.

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

Vite plugins MUST ALWAYS query `this.environment.name` in transform/resolve hooks before operating on module graphs to prevent injecting server logic into the `client` environment.

Vite plugins MUST ALWAYS query `this.environment.name` in transform/resolve hooks before operating on module graphs to prevent injecting server logic into the `client` environment.

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 configure an explicit compile-time fence plugin that rejects imports of `$env/server/*`, `server-only`, or sensitive credential registries whenever `this.environment.name === 'client'`.

Engineers MUST configure an explicit compile-time fence plugin that rejects imports of `$env/server/*`, `server-only`, or sensitive credential registries whenever `this.environment.name === 'client'`.

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

Modules containing private server logic MUST specify subpath exports with runtime conditions or fail-safe barriers preventing import from client-facing graphs.

Modules containing private server logic MUST specify subpath exports with runtime conditions or fail-safe barriers preventing import from client-facing graphs.

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 Multi-Runtime Environment API Secret Fence Standard critical for AI coding assistants?

Enforces strict compile-time boundary isolation across Vite 6 Environment API runtimes (Client, Node SSR, Edge). Prevents server-only credentials, platform bindings, and non-distributable server module graphs from leaking into client-targeted compilation units. 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-Runtime Module Graph Contamination Leaking Server Secrets into Client Artifacts) 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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