perf: remove JS side config validation

[chenjiahan]

Summary

This PR removes Zod validation, the validation logic has been stripped from various plugins and configuration files, and the Zod-related dependencies has been removed.

Motivation

• Improved startup performance: Zod schema validation introduced about 20–40 ms of overhead, skipping it noticeably speeds up startup.
• Modern applications typically rely on TypeScript for config validation — it offers better type hints without impacting build performance.
  *-// @ts-check is now added by default in create-rspack: feat(create-rspack): add type annotations to JS configs #11896
• Rsbuild removed Zod validation 3 months ago with no negative impact: perf: disable Rspack config schema validation rsbuild#5475
• Rspack also performs some validations in Rust side, such as swc-loader option validations, which provides clearer and more direct diagnostics than Zod:

Performance

• 20+ms faster:

• @rspack/core/dist/index.js is 210.2KB smaller (863.5KB -> 653.3KB)

TODO

• Optimize duplicate errors caused by multiple #getInstance calls
• Improve additional option validation for swc-loader

Checklist

• Tests updated (or not required).
• Documentation updated (or not required).

[netlify]

✅ Deploy Preview for rspack canceled.

Name	Link
🔨 Latest commit	f674db1
🔍 Latest deploy log	https://app.netlify.com/projects/rspack/deploys/68f207b11990420009724a6d

[Copilot]

Pull Request Overview

This PR removes Zod validation from Rspack's JavaScript configuration validation layer, aiming to improve startup performance by 20-40ms. The validation logic has been completely stripped from plugins, configuration files, and the core Rspack module, with Zod dependencies removed from the package.

Key changes:

• Removed all Zod schema validation from the JavaScript layer
• Eliminated validation-related environment variables and test cases
• Moved ValidationError to RspackError module for backward compatibility

Reviewed Changes

Copilot reviewed 34 out of 35 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
packages/rspack/src/schema/	Complete removal of Zod validation schemas and utilities
packages/rspack/src/rspack.ts	Removed validation calls from main rspack function
packages/rspack/src/builtin-plugin/	Stripped validation from all builtin plugins
packages/rspack/src/exports.ts	Moved ValidationError export location
packages/rspack/src/RspackError.ts	Added deprecated ValidationError class
tests/rspack-test/	Removed validation tests and environment variable settings
website/docs/	Updated documentation to remove validation mode references
packages/rspack/package.json	Removed zod and zod-validation-error dependencies

Files not reviewed (1)

• pnpm-lock.yaml: Language not supported

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}

[github-actions]

📦 Binary Size-limit

Comparing f674db1 to test: Revert 'migrate config tests to rstest (#11895)' (#11902) by 9aoy

❌ Size increased by 256bytes from 47.67MB to 47.67MB (⬆️0.00%)

[codspeed-hq]

CodSpeed Performance Report

Merging #11897 will not alter performance

_{Comparing remove_zod_1016 (f674db1) with main (1ff04bd)}

Summary

✅ 17 untouched