[Tracking]: Storybook 9 Breaking Changes and Packages Cleanup

[valentinpalkovic]

Milestones

Milestone: Core Consolidation & Internal API Reorganization

Owner: @ndelangen
Complete: February 25 → March 18
Progress:

Description:
This milestone aims to finalize the consolidation of core packages, streamline API exposure, and remove unnecessary dependencies to reduce bloat and improve maintainability. The work will impact both internal and public APIs, requiring migration strategies and automations for a smooth transition.

Tracking Issue: #30674

Milestone: Test-Related Package Consolidation

Owner: @valentinpalkovic
Complete: February 25 → March 4
Progress:

Description:
This milestone aims to consolidate test-related packages into a unified @storybook/addon-test package. The goal is to simplify testing workflows and ensure all relevant test utilities are maintained under a single addon. The work requires package migrations, updates to CLI behavior, automigrations, and comprehensive documentation.

Tracking Issue: #30675

Milestone: Update the Viewport and Backgrounds Addon

Owner: @ndelangen
Complete: March 18 → March 21
Progress:

Description:
This milestone aims to finalize the schema change for the viewport and background global, remove feature flags, and improve viewport and background configuration options in Storybook to align support the legacy magic string format.

Tracking Issue: #30678

Milestone: Remove Deprecations and Drop Tooling Support

Owner: @valentinpalkovic
Complete: March 4 → March 12
Progress:

Description:
This milestone focuses on removing deprecated features and outdated tooling support to streamline Storybook 9. The work includes the deprecations and tooling removals listed in the linked issues. It also involves ensuring clear migration paths for affected users and improving related documentation.

Tracking Issue: #30679

Milestone: Addon Author Outreach & Documentation

Owner: @valentinpalkovic
Complete: March 23 -> March 25
Progress:

Description:
This milestone focuses on ensuring a smooth transition for addon authors by providing a comprehensive migration guide and conducting community outreach similar to Storybook 8. The goal is to minimize migration friction, help maintainers update their addons, and keep the ecosystem stable through Storybook 9.

Tracking Issue: #30680

Milestone: Merging Addon Functionality into Core [NICE TO HAVE]

Owner: @ndelangen
Complete: March 21 -> March 28
Progress:

Description:
This milestone aims to merge multiple standalone Storybook addons into the core framework, reducing package fragmentation and improving performance. The goal is to simplify maintenance, improve user experience, and streamline configuration for users by making these addons part of the core manager.

Tracking Issue: #30710

Milestone: Additional Cleanups & Framework Integrations [NICE TO HAVE]

Owner: @ndelangen
Complete: March 25 -> March 27
Progress:

Description:
This milestone aims to do further cleanups, like removing @storybook/globals and use globalThis instead or merging the remaining webpack specific presets into their respective frameworks.

Tracking Issue: #30712

Notes:

• Potential nice to have item: Prebundle renderer and builder into framework