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frontendcritical PriorityID: vite-6-rolldown-deterministic-chunking

Vite 6 & Rolldown Deterministic Chunk Boundary & AST Hashing Invariant

Enforces identical AST module partitioning, pure vendor boundary allocations, and deterministic content-addressed hash generation between client and SSR module execution graphs. Prevents dynamic import skew, cross-boundary symbol leaks, and cascading runtime hydration mismatches during rolling canary rollouts.

Prohibited Anti-Pattern: Non-Deterministic Manual Chunk Splitting Causing SSR/Client Split-Graph Divergence

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---
description: Vite 6 & Rolldown Deterministic Chunk Boundary & AST Hashing Invariant - Enforces identical AST module partitioning, pure vendor boundary allocations, and deterministic content-addressed hash generation between client and SSR module execution graphs. Prevents dynamic import skew, cross-boundary symbol leaks, and cascading runtime hydration mismatches during rolling canary rollouts.
globs: vite.config.{ts,js,mjs}, src/**/*.{ts,tsx,js,jsx}, server/**/*.{ts,js}
alwaysApply: true
verified_by: "agentrules.org"
license: "CC-BY-4.0"
source: "https://agentrules.org/rules/vite-6-rolldown-deterministic-chunking"
---

# Vite 6 & Rolldown Deterministic Chunk Boundary & AST Hashing Invariant

> **Severity**: CRITICAL | **Category**: frontend
> **Anti-Pattern Warning**: Non-Deterministic Manual Chunk Splitting Causing SSR/Client Split-Graph Divergence

## System Constraints
You are a Principal Software Architect enforcing deterministic module compilation and chunk layout equivalence across dual-runtime (SSR Node/Edge and Client DOM) environments powered by Vite 6 and Rolldown/Rollup. You must prevent dynamic graph skew, runtime-conditional static imports, non-deterministic manualChunks functions, and hash collisions across staggered deployments.

## Strict Guidelines
- Engineers MUST ALWAYS configure `build.rollupOptions.output.manualChunks` using deterministic AST structural predicates or pure package manifests rather than runtime-varying path strings.
- Engineers MUST NEVER introduce client-only or server-only dynamic side effects directly inside synchronously shared module evaluation scopes.
- Code SHOULD use static, top-level type imports (`import type`) across SSR-Client boundaries to prevent Rolldown from emitting phantom intermediate bridge chunks.
- Services MUST ensure `build.rollupOptions.output.chunkFileNames` and `assetFileNames` utilize content-addressed hashes (`[name]-[hash].js`) evaluated uniformly across target runtimes.
- Components NEVER dynamically import modules with non-deterministic runtime expressions or variable interpolation templates (e.g., `import(`./views/${name}`)`) without explicit Rolldown glob guards.
- Engineers MUST synchronize the `ssr` and `client` build manifest mappings to verify 1:1 chunk symbol integrity before promoting canary deployments.

## Bad vs Good Implementations
### Deterministic Shared Chunk Boundary Strategy

#### Bad Antipattern (AI Common Hallucination)
> **Why it fails**: Arbitrary substring matching and non-isolated vendor catch-alls destabilize chunk boundary resolution between SSR and client builds. When a module is imported in SSR but treeshaken out of client (or vice-versa), Rolldown isolates transitive dependencies into separate bridge chunks, changing hash fingerprints and causing hydration failure code 418/423 during rolling deployments.
```typescript
// vite.config.ts
import { defineConfig } from 'vite';

export default defineConfig({
  build: {
    rollupOptions: {
      output: {
        // ANTI-PATTERN: Non-deterministic string splitting causes SSR and Client
        // graph topology divergence and circular dependency chunk fragmentation
        manualChunks(id) {
          if (id.includes('node_modules')) {
            if (id.includes('react')) return 'vendor-react';
            if (id.includes('lodash')) return 'vendor-utils';
            return 'vendor'; // Volatile bucket causing hash cascade changes
          }
          if (Math.random() > 0.5) return 'random-chunk'; // Extreme non-determinism
        }
      }
    }
  }
});
```

#### Production Standard (Correct)
> **Standard**: Normalizes platform path separators, enforces explicit, package-boundary mapping for shared runtime singletons, and eliminates intermediate transient groupings. This ensures both SSR manifests and client-side chunks resolve identical content hashes and preserve execution boundaries during rolling rollouts.
```typescript
// vite.config.ts
import { defineConfig } from 'vite';

// Package-exact deterministic matching
const VENDOR_LIBS: Record<string, string> = {
  'react': 'framework',
  'react-dom': 'framework',
  '@tanstack/react-query': 'data-core'
};

export default defineConfig({
  build: {
    sourcemap: true,
    rollupOptions: {
      output: {
        // DETERMINISTIC: Consistent AST node isolation for both client and SSR runtimes
        manualChunks(id: string): string | void {
          if (!id.includes('node_modules/')) return;
          
          const normalizedId = id.replace(/\\/g, '/');
          const segments = normalizedId.split('node_modules/')[1]?.split('/');
          if (!segments || segments.length === 0) return;
          
          const packageName = segments[0].startsWith('@') 
            ? `${segments[0]}/${segments[1]}` 
            : segments[0];
            
          if (packageName in VENDOR_LIBS) {
            return VENDOR_LIBS[packageName];
          }
        },
        chunkFileNames: 'assets/[name]-[hash:16].js',
        entryFileNames: 'assets/[name]-[hash:16].js'
      }
    }
  }
});
```
Recommended MCP Servers (mcp-serverlist.com)

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

Vite Manifest Inspector MCP
Analyzes client and SSR manifest graphs post-build to detect chunk boundary divergence, circular dependencies, and hash shifts before production releases.
Recommended Agent Skills (askills.dev)

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

Rolldown & Rollup Bundle Visualizer Diff
Compares dual-graph emission artifacts across client and SSR bundles to flag asymmetric chunk partitioning.
Architectural Specification & Invariant Rationale

Architectural Invariant Design: Vite 6 & Rolldown Deterministic Chunk Boundary & AST Hashing Invariant

Vite 6 & Rolldown Deterministic Chunk Boundary & AST Hashing Invariant defines an industrial-grade behavioral standard for frontend engineering. Enforces identical AST module partitioning, pure vendor boundary allocations, and deterministic content-addressed hash generation between client and SSR module execution graphs. Prevents dynamic import skew, cross-boundary symbol leaks, and cascading runtime hydration mismatches during rolling canary rollouts. 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: Non-Deterministic Manual Chunk Splitting Causing SSR/Client Split-Graph Divergence 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 DriftNon-Deterministic Manual Chunk Splitting Causing SSR/Client Split-Graph DivergenceCritical
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 `build.rollupOptions.output.manualChunks` using deterministic AST structural predicates or pure package manifests rather than runtime-varying path strings.

Engineers MUST ALWAYS configure `build.rollupOptions.output.manualChunks` using deterministic AST structural predicates or pure package manifests rather than runtime-varying path strings.

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 NEVER introduce client-only or server-only dynamic side effects directly inside synchronously shared module evaluation scopes.

Engineers MUST NEVER introduce client-only or server-only dynamic side effects directly inside synchronously shared module evaluation scopes.

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 SHOULD use static, top-level type imports (`import type`) across SSR-Client boundaries to prevent Rolldown from emitting phantom intermediate bridge chunks.

Code SHOULD use static, top-level type imports (`import type`) across SSR-Client boundaries to prevent Rolldown from emitting phantom intermediate bridge chunks.

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 ensure `build.rollupOptions.output.chunkFileNames` and `assetFileNames` utilize content-addressed hashes (`[name]-[hash].js`) evaluated uniformly across target runtimes.

Services MUST ensure `build.rollupOptions.output.chunkFileNames` and `assetFileNames` utilize content-addressed hashes (`[name]-[hash].js`) evaluated uniformly across target 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 NEVER dynamically import modules with non-deterministic runtime expressions or variable interpolation templates (e.g., `import(`./views/${name}`)`) without explicit Rolldown glob guards.

Components NEVER dynamically import modules with non-deterministic runtime expressions or variable interpolation templates (e.g., `import(`./views/${name}`)`) without explicit Rolldown glob guards.

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

Engineers MUST synchronize the `ssr` and `client` build manifest mappings to verify 1

Engineers MUST synchronize the `ssr` and `client` build manifest mappings to verify 1:1 chunk symbol integrity before promoting canary deployments.

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 & Rolldown Deterministic Chunk Boundary & AST Hashing Invariant critical for AI coding assistants?

Enforces identical AST module partitioning, pure vendor boundary allocations, and deterministic content-addressed hash generation between client and SSR module execution graphs. Prevents dynamic import skew, cross-boundary symbol leaks, and cascading runtime hydration mismatches during rolling canary rollouts. 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 (Non-Deterministic Manual Chunk Splitting Causing SSR/Client Split-Graph Divergence) 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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