Builder-Vite: Disable Vite publicDir to prevent conflicts with Storybook's staticDirs

[yatishgoel]

Closes #24627

What I did

Disabled Vite's default publicDir copying in the Storybook Vite builder config to prevent conflicts with
Storybook's staticDirs.

The Problem:
Vite automatically copies the publicDir (defaults to public/) to the build output root. This causes issues
when:

• Users have files in public/ that conflict with Storybook's generated files (e.g., index.json)
• Users configure staticDirs to place public assets elsewhere, but Vite still copies to root

The Fix:

• Added publicDir: false to Storybook's Vite builder config
• Users should use Storybook's staticDirs config to manage static assets instead
• Added unit test to ensure this behavior is maintained

Example of the bug:

# Before fix: public/index.json overwrites Storybook's index.json                                               
storybook-static/index.json = {"broken": true}  ❌                                                              
                                                                                                                
# After fix: Storybook's index.json is preserved                                                                
storybook-static/index.json = {"v":5,"entries":{...}}  ✅         

Checklist for Contributors

Testing

The changes in this PR are covered in the following automated tests:

• stories
• unit tests
• integration tests
• end-to-end tests

Manual testing

Caution

This section is mandatory for all contributions. If you believe no manual test is necessary, please state so explicitly. Thanks!

Documentation

• Add or update documentation reflecting your changes
• If you are deprecating/removing a feature, make sure to update
  MIGRATION.MD

Checklist for Maintainers

• When this PR is ready for testing, make sure to add ci:normal, ci:merged or ci:daily GH label to it to run a specific set of sandboxes. The particular set of sandboxes can be found in code/lib/cli-storybook/src/sandbox-templates.ts

• Make sure this PR contains one of the labels below:

  Available labels

  • bug: Internal changes that fixes incorrect behavior.
  • maintenance: User-facing maintenance tasks.
  • dependencies: Upgrading (sometimes downgrading) dependencies.
  • build: Internal-facing build tooling & test updates. Will not show up in release changelog.
  • cleanup: Minor cleanup style change. Will not show up in release changelog.
  • documentation: Documentation only changes. Will not show up in release changelog.
  • feature request: Introducing a new feature.
  • BREAKING CHANGE: Changes that break compatibility in some way with current major version.
  • other: Changes that don't fit in the above categories.

🦋 Canary release

This PR does not have a canary release associated. You can request a canary release of this pull request by mentioning the @storybookjs/core team here.

core team members can create a canary release here or locally with gh workflow run --repo storybookjs/storybook publish.yml --field pr=<PR_NUMBER>

Summary by CodeRabbit

• Bug Fixes

  • Fixed Vite builder configuration to prevent conflicts between public directory and static directories.

• Tests

  • Added test coverage for file-based configuration handling in the Vite builder.

_{✏️ Tip: You can customize this high-level summary in your review settings.}

[coderabbitai]

📝 Walkthrough

Walkthrough

Adds publicDir: false configuration to the Vite builder's common config and includes a test case to verify the setting is applied when loading file-based configurations. This prevents the public directory from being served, avoiding conflicts with staticDirs.

Changes

Cohort / File(s)	Summary
Vite Configuration with publicDir Flag code/builders/builder-vite/src/vite-config.ts, code/builders/builder-vite/src/vite-config.test.ts	Adds publicDir: false to sbConfig in the common Vite configuration, with a corresponding test case verifying the setting is properly applied when loading file-based configs.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~5 minutes

✨ Finishing touches

• 📝 Generate docstrings

---

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[storybook-app-bot]

Package Benchmarks

^{Commit: f8fd78f, ran on 2 February 2026 at 13:34:05 UTC}

The following packages have significant changes to their size or dependencies:

@storybook/cli

	Before	After	Difference
Dependency count	183	183	0
Self size	776 KB	776 KB	0 B
Dependency size	67.55 MB	67.54 MB	🎉 -10 KB 🎉
Bundle Size Analyzer	Link	Link