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

Vite 6 Environment API Dual-Target Compilation Secret Guardrail

Enforces strict module graph boundary validation across Vite 6 environments (client, ssr, workerd) using the Environment API. Prevents private server credentials, database connections, and server-only modules from bridging into client and edge workerd compilation targets during multi-environment builds.

Prohibited Anti-Pattern: Cross-environment leakage of server secrets into client bundle via unpartitioned Vite 6 Environment module graphs

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---
description: Vite 6 Environment API Dual-Target Compilation Secret Guardrail - Enforces strict module graph boundary validation across Vite 6 environments (client, ssr, workerd) using the Environment API. Prevents private server credentials, database connections, and server-only modules from bridging into client and edge workerd compilation targets during multi-environment builds.
globs: vite.config.ts, vite.config.*.ts, src/**/*.{ts,tsx}, src/**/*.server.{ts,tsx}, src/**/env.{ts,js}
alwaysApply: true
verified_by: "agentrules.org"
license: "CC-BY-4.0"
source: "https://agentrules.org/rules/vite6-environment-api-secret-guardrail"
---

# Vite 6 Environment API Dual-Target Compilation Secret Guardrail

> **Severity**: CRITICAL | **Category**: frontend
> **Anti-Pattern Warning**: Cross-environment leakage of server secrets into client bundle via unpartitioned Vite 6 Environment module graphs

## System Constraints
You are a Principal Software Architect enforcing Vite 6 Environment API Dual-Target Compilation Secret Guardrails. Vite 6 decouples runtimes into explicit compilation environments (e.g., client, ssr, workerd). You must ensure server-only modules, private environmental configurations, and backend secrets are categorically unreachable from client and edge workerd target module graphs.

## Strict Guidelines
- Engineers MUST ALWAYS configure environment boundary plugins that inspect 'this.environment.name' in Vite 6 hooks to reject server-only modules during client or untrusted edge compilation.
- Engineers MUST NOT import files matching '*.server.ts' or any module consuming non-prefixed server secrets inside components or utilities reachable by the client environment graph.
- Vite 6 configuration MUST explicitly define isolated environments ('environments.client', 'environments.ssr', 'environments.workerd') with segregated define mappings and externalized server boundaries.
- Plugins MUST throw a fatal compilation error during 'resolveId' or 'load' if a client environment requests an asset flagged as server-only or containing non-public credentials.
- Components NEVER directly read process.env or non-public variables; runtime configurations MUST pass through strict, environment-validated conduits.

## Bad vs Good Implementations
### Module Boundary Protection in Vite 6 Environment API

#### Bad Antipattern (AI Common Hallucination)
> **Why it fails**: The 'define' block exposes sensitive server-only variables (DB_CONNECTION_STRING) to all Vite 6 compilation environments, including the client target. Furthermore, it lacks boundary enforcement hooks to prevent .server.ts modules from being imported into client bundles.
```typescript
import { defineConfig } from 'vite';

// Flawed: Single-pass config or naive Vite 6 environment setup without boundary assertion
export default defineConfig({
  environments: {
    client: {
      build: { outDir: 'dist/client' }
    },
    ssr: {
      build: { outDir: 'dist/server' }
    }
  },
  define: {
    // DANGEROUS: Leaks server secret into global scope across all environments
    'process.env.DB_CONNECTION_STRING': JSON.stringify(process.env.DB_CONNECTION_STRING),
    'process.env.PUBLIC_API_URL': JSON.stringify(process.env.PUBLIC_API_URL)
  }
});
```

#### Production Standard (Correct)
> **Standard**: Implements an environment-aware compilation guardrail using 'this.environment.name' to block '*.server.ts' imports into client graphs. Segregates environment-specific define replacements within Vite 6's environment configurations, eliminating secret leakage.
```typescript
import { defineConfig, type Plugin } from 'vite';

function enforceEnvironmentBoundaries(): Plugin {
  return {
    name: 'vite-environment-secret-guardrail',
    enforce: 'pre',
    resolveId(source, importer) {
      const envName = this.environment?.name ?? 'client';
      const isServerOnlyModule = /\.server(\.[cm]?[jt]sx?)?$/.test(source) || source.includes('/server/');
      
      if (envName === 'client' && isServerOnlyModule) {
        throw new Error(
          `[Security Violation] Target environment 'client' attempted to import server-only module: '${source}' from '${importer}'.`
        );
      }
      return null;
    }
  };
}

export default defineConfig({
  plugins: [enforceEnvironmentBoundaries()],
  environments: {
    client: {
      define: {
        'import.meta.env.PUBLIC_API_URL': JSON.stringify(process.env.PUBLIC_API_URL)
      },
      build: {
        outDir: 'dist/client'
      }
    },
    ssr: {
      define: {
        'process.env.DB_CONNECTION_STRING': JSON.stringify(process.env.DB_CONNECTION_STRING),
        'import.meta.env.PUBLIC_API_URL': JSON.stringify(process.env.PUBLIC_API_URL)
      },
      build: {
        outDir: 'dist/server'
      }
    }
  }
});
```
Recommended MCP Servers (mcp-serverlist.com)

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

Secret Boundary Lint MCP
Scans emitted compilation chunks across multiple environments to ensure zero server-token leakage.
Recommended Agent Skills (askills.dev)

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

Vite 6 Module Graph Validator
Inspects Vite 6 environment module graphs and flags cross-target references before artifact emission.
Architectural Specification & Invariant Rationale

Architectural Invariant Design: Vite 6 Environment API Dual-Target Compilation Secret Guardrail

Vite 6 Environment API Dual-Target Compilation Secret Guardrail defines an industrial-grade behavioral standard for frontend engineering. Enforces strict module graph boundary validation across Vite 6 environments (client, ssr, workerd) using the Environment API. Prevents private server credentials, database connections, and server-only modules from bridging into client and edge workerd compilation targets during multi-environment builds. 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 leakage of server secrets into client bundle via unpartitioned Vite 6 Environment module graphs 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 leakage of server secrets into client bundle via unpartitioned Vite 6 Environment module graphsCritical
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 environment boundary plugins that inspect 'this.environment.name' in Vite 6 hooks to reject server-only modules during client or untrusted edge compilation.

Engineers MUST ALWAYS configure environment boundary plugins that inspect 'this.environment.name' in Vite 6 hooks to reject server-only modules during client or untrusted edge compilation.

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 import files matching '*.server.ts' or any module consuming non-prefixed server secrets inside components or utilities reachable by the client environment graph.

Engineers MUST NOT import files matching '*.server.ts' or any module consuming non-prefixed server secrets inside components or utilities reachable by 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.
3

Vite 6 configuration MUST explicitly define isolated environments ('environments.client', 'environments.ssr', 'environments.workerd') with segregated define mappings and externalized server boundaries.

Vite 6 configuration MUST explicitly define isolated environments ('environments.client', 'environments.ssr', 'environments.workerd') with segregated define mappings and externalized server boundaries.

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

Plugins MUST throw a fatal compilation error during 'resolveId' or 'load' if a client environment requests an asset flagged as server-only or containing non-public credentials.

Plugins MUST throw a fatal compilation error during 'resolveId' or 'load' if a client environment requests an asset flagged as server-only or containing non-public credentials.

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 NEVER directly read process.env or non-public variables

Components NEVER directly read process.env or non-public variables; runtime configurations MUST pass through strict, environment-validated conduits.

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 Dual-Target Compilation Secret Guardrail critical for AI coding assistants?

Enforces strict module graph boundary validation across Vite 6 environments (client, ssr, workerd) using the Environment API. Prevents private server credentials, database connections, and server-only modules from bridging into client and edge workerd compilation targets during multi-environment builds. 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 leakage of server secrets into client bundle via unpartitioned Vite 6 Environment module graphs) 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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