CSF: Fix export interface declaration for NextPreview

[icopp]

Relates to #32898

What I did

This interface has to be exported to prevent "Default export of the module has or is using private name" errors when attempting to import definePreview.

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

1. Create a simple preview.tsx for a Storybook project, for example:

   import { definePreview } from "@storybook/nextjs";
   
   export default definePreview({});
   

2. See that there is a type error before this change, and no type error after this change

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

• Refactor
  • Updated public API to expose the NextPreview type for external use.

[nx-cloud]

View your CI Pipeline Execution ↗ for commit f57d119

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☁️ Nx Cloud last updated this comment at 2025-11-03 14:45:27 UTC

[coderabbitai]

📝 Walkthrough

Walkthrough

The NextPreview interface in the Next.js framework index file is now publicly exported by adding the export keyword. No logic or runtime behavior is altered.

Changes

Cohort / File(s)	Summary
Export Addition code/frameworks/nextjs/src/index.ts	NextPreview interface changed from non-exported to exported; signature updated to include export keyword before interface declaration

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~2 minutes

✨ Finishing touches

• 📝 Generate docstrings

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📜 Recent review details

Configuration used: CodeRabbit UI

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 5d0ff07 and f57d119.

📒 Files selected for processing (1)

• code/frameworks/nextjs/src/index.ts (1 hunks)

🧰 Additional context used

📓 Path-based instructions (4)

**/*.{js,jsx,json,html,ts,tsx,mjs}

📄 CodeRabbit inference engine (.github/copilot-instructions.md)

**/*.{js,jsx,json,html,ts,tsx,mjs}: Run Prettier formatting on changed files before committing
Run ESLint on changed files and fix all errors/warnings before committing (use yarn lint:js:cmd <file>)

Files:

• code/frameworks/nextjs/src/index.ts

**/*.{ts,tsx,js,jsx,mjs}

📄 CodeRabbit inference engine (.github/copilot-instructions.md)

Export functions from modules when they need to be unit-tested

Files:

• code/frameworks/nextjs/src/index.ts

code/**/*.{ts,tsx,js,jsx,mjs}

📄 CodeRabbit inference engine (.github/copilot-instructions.md)

In application code, use Storybook loggers instead of console.* (client code: storybook/internal/client-logger; server code: storybook/internal/node-logger)

Files:

• code/frameworks/nextjs/src/index.ts

{code/**,scripts/**}/**/*.{ts,tsx,js,jsx,mjs}

📄 CodeRabbit inference engine (.github/copilot-instructions.md)

Do not use console.log, console.warn, or console.error directly unless in isolated files where importing loggers would significantly increase bundle size

Files:

• code/frameworks/nextjs/src/index.ts

🧠 Learnings (1)

📓 Common learnings

Learnt from: CR
Repo: storybookjs/storybook PR: 0
File: .github/copilot-instructions.md:0-0
Timestamp: 2025-10-13T13:33:14.659Z
Learning: Applies to **/*.{ts,tsx,js,jsx,mjs} : Export functions from modules when they need to be unit-tested

🧬 Code graph analysis (1)

code/frameworks/nextjs/src/index.ts (2)

code/core/src/csf/story.ts (1)

• AddonTypes (174-177)

code/renderers/react/src/preview.tsx (1)

• ReactPreview (56-81)

⏰ Context from checks skipped due to timeout of 90000ms. You can increase the timeout in your CodeRabbit configuration to a maximum of 15 minutes (900000ms). (3)

• GitHub Check: normal
• GitHub Check: Danger JS
• GitHub Check: Core Unit Tests, windows-latest

🔇 Additional comments (1)

code/frameworks/nextjs/src/index.ts (1)

26-26: LGTM! Correctly fixes the TypeScript visibility error.

Exporting the NextPreview interface resolves the TypeScript error because definePreview (line 16) returns this type. TypeScript requires that return types of exported functions be publicly accessible.

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[yannbf]

Thanks a lot for your contribution!

[storybook-app-bot]

Package Benchmarks

^{Commit: f57d119, ran on 6 November 2025 at 15:23:13 UTC}

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

@storybook/nextjs

	Before	After	Difference
Dependency count	533	533	0
Self size	749 KB	749 KB	0 B
Dependency size	58.93 MB	58.91 MB	🎉 -20 KB 🎉
Bundle Size Analyzer	Link	Link

@storybook/nextjs-vite

	Before	After	Difference
Dependency count	124	124	0
Self size	3.83 MB	3.83 MB	🎉 -250 B 🎉
Dependency size	21.87 MB	21.85 MB	🎉 -20 KB 🎉
Bundle Size Analyzer	Link	Link

@storybook/react-native-web-vite

	Before	After	Difference
Dependency count	157	157	0
Self size	31 KB	31 KB	0 B
Dependency size	23.11 MB	23.09 MB	🎉 -20 KB 🎉
Bundle Size Analyzer	Link	Link

@storybook/react-vite

	Before	After	Difference
Dependency count	114	114	0
Self size	37 KB	37 KB	🎉 -24 B 🎉
Dependency size	19.67 MB	19.65 MB	🎉 -20 KB 🎉
Bundle Size Analyzer	Link	Link

@storybook/react-webpack5

	Before	After	Difference
Dependency count	273	273	0
Self size	25 KB	25 KB	0 B
Dependency size	43.89 MB	43.87 MB	🎉 -20 KB 🎉
Bundle Size Analyzer	Link	Link

@storybook/react

	Before	After	Difference
Dependency count	57	57	0
Self size	833 KB	812 KB	🎉 -20 KB 🎉
Dependency size	12.92 MB	12.92 MB	0 B
Bundle Size Analyzer	Link	Link