Release: Prerelease 10.4.0-alpha.12

[github-actions]

This is an automated pull request that bumps the version from 10.4.0-alpha.11 to 10.4.0-alpha.12.
Once this pull request is merged, it will trigger a new release of version 10.4.0-alpha.12.
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: CLI: Introduce Agentic Setup workflow #34297
• 🏗️ Build: Maintenance: Share constant for .rnstorybook #34653
• 📝 Documentation: Docs: Improve fn details for Actions #34654 (will also be patched)

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.12

• CLI: Introduce Agentic Setup workflow - #34297, thanks yannbf!

[storybook-app-bot]

Package Benchmarks

^{Commit: 7cf97be, ran on 30 April 2026 at 10:45:34 UTC}

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

storybook

	Before	After	Difference
Dependency count	50	50	0
Self size	20.55 MB	20.58 MB	🚨 +36 KB 🚨
Dependency size	16.56 MB	16.56 MB	0 B
Bundle Size Analyzer	Link	Link

@storybook/cli

	Before	After	Difference
Dependency count	184	184	0
Self size	782 KB	836 KB	🚨 +54 KB 🚨
Dependency size	68.22 MB	68.26 MB	🚨 +44 KB 🚨
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	66.74 MB	66.78 MB	🚨 +37 KB 🚨
Bundle Size Analyzer	Link	Link

create-storybook

	Before	After	Difference
Dependency count	51	51	0
Self size	1.04 MB	1.05 MB	🚨 +8 KB 🚨
Dependency size	37.10 MB	37.14 MB	🚨 +36 KB 🚨
Bundle Size Analyzer	node	node