Release: Prerelease 10.4.0-alpha.9

[github-actions]

This is an automated pull request that bumps the version from 10.4.0-alpha.8 to 10.4.0-alpha.9.
Once this pull request is merged, it will trigger a new release of version 10.4.0-alpha.9.
If you're not a core maintainer with permissions to release you can ignore this pull request.

To do

Before merging the PR, there are a few QA steps to go through:

• Add the "freeze" label to this PR, to ensure it doesn't get automatically forced pushed by new changes.
• Add the "ci:daily" label to this PR, to trigger the full test suite to run on this PR.

And for each change below:

1. Ensure the change is appropriate for the version bump. E.g. patch release should only contain patches, not new or de-stabilizing features. If a change is not appropriate, revert the PR.
2. Ensure the PR is labeled correctly with one of: "BREAKING CHANGE", "feature request", "bug", "maintenance", "dependencies", "documentation", "build", "unknown".
3. Ensure the PR title is correct, and follows the format "[Area]: [Summary]", e.g. "React: Fix hooks in CSF3 render functions". If it is not correct, change the title in the PR.
   • Areas include: React, Vue, Core, Docs, Controls, etc.
   • First word of summary indicates the type: “Add”, “Fix”, “Upgrade”, etc.
   • The entire title should fit on a line

This is a list of all the PRs merged and commits pushed directly to next, that will be part of this release:

• ✨ Feature Request: React: Add subcomponents to component manifests #34428 (will also be patched)
• 🐛 Bug: Addon-Docs: Avoid rerendering static Source blocks #34206
• 🐛 Bug: A11y: Improve boolean control contrast in forced colors mode #34204
• 🐛 Bug: Vue3: Clear stale args/globals when nextArgs is empty in updateArgs #34409
• 🐛 Bug: Fix: Add vite-plus vendored libraries version detection #34509 (will also be patched)
• 🔧 Maintenance: CLI: Streamline Node.js version detection code #34440
• 🔧 Maintenance: Core: Improve startup performance by deferring change detection initialization #34498
• 🐛 Bug: Nextjs: Handle node builtin webpack imports #34494
• 🐛 Bug: Core: Normalize file paths in ChangeDetectionService and trace-changed for Windows support #34445
• 📝 Documentation: Docs: Fix stroybook typo in core readme #34486
• 📝 Documentation: Docs: Add AI contributions guide in contributing.md and documentation #34502 (will also be patched)
• 🏗️ Build: CI: Avoid shallow checkout for Chromatic job #34483

If you've made any changes doing the above QA (change PR titles, revert PRs), manually trigger a re-generation of this PR with this workflow and wait for it to finish. It will wipe your progress in this to do, which is expected.

Feel free to manually commit any changes necessary to this branch after you've done the last re-generation, following the Make Manual Changes section in the docs, especially if you're making changes to the changelog.

When everything above is done:

• Merge this PR
• Follow the run of the publish action

---

Generated changelog

10.4.0-alpha.9

• A11y: Improve boolean control contrast in forced colors mode - #34204, thanks anchmelev!
• Addon-Docs: Avoid rerendering static Source blocks - #34206, thanks anchmelev!
• CLI: Streamline Node.js version detection code - #34440, thanks Sidnioulz!
• Core: Improve startup performance by deferring change detection initialization - #34498, thanks ghengeveld!
• Core: Normalize file paths in ChangeDetectionService and trace-changed for Windows support - #34445, thanks ghengeveld!
• Fix: Add vite-plus vendored libraries version detection - #34509, thanks huang-julien!
• Nextjs: Handle node builtin webpack imports - #34494, thanks JReinhold!
• React: Add subcomponents to component manifests - #34428, thanks kasperpeulen!
• Vue3: Clear stale args/globals when nextArgs is empty in updateArgs - #34409, thanks whdjh!

[storybook-app-bot]

Package Benchmarks

^{Commit: d03c54d, ran on 14 April 2026 at 09:09:02 UTC}

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

storybook

	Before	After	Difference
Dependency count	50	50	0
Self size	20.52 MB	20.53 MB	🚨 +10 KB 🚨
Dependency size	16.56 MB	16.56 MB	🚨 +93 B 🚨
Bundle Size Analyzer	Link	Link

@storybook/codemod

	Before	After	Difference
Dependency count	177	177	0
Self size	32 KB	32 KB	0 B
Dependency size	66.68 MB	66.69 MB	🚨 +11 KB 🚨
Bundle Size Analyzer	Link	Link

create-storybook

	Before	After	Difference
Dependency count	51	51	0
Self size	1.04 MB	1.04 MB	🎉 -1 KB 🎉
Dependency size	37.07 MB	37.08 MB	🚨 +11 KB 🚨
Bundle Size Analyzer	node	node