Vitest: Fallback detecting vitest version in postinstall

[ndelangen]

Closes #33410

What I did

I copied the fallback mechanism found in AddonVitestService to the postinstall. Though this is no longer really needed due to the second fix in this PR:

I have figured out why the packageManager.getInstalledVersion('vitest') is failing:

When this command is executed:

pnpm list "vitest" --json --depth=99

pnpm exits with code=1, with this error:

"code": "EINVALIDTAGNAME",
"message": "Invalid tag name \"\"vitest\"\": Tags may not have any characters that encodeURIComponent encodes."

Running the command with shell:true resolves the problem.

It seemed both pnpm and yarn1 PackageManager-instances were affected by this.

I've added additional debug logging to make the errors easier to find in the future.

Another discovery was that the config-file getting edited/generated for addon-vitest can get out of sync with the version getting add/installed due to a missing semver.coerce.

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

I've tested a canary with just the fallback addition.

Then I switched to running the bin directly off a development branch, as suggested by the issue.
Adding debug logging until I was able to figure out why the installed version was not correctly detected.

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 pull request has been released as version 0.0.0-pr-33415-sha-8542def9. Try it out in a new sandbox by running npx storybook@0.0.0-pr-33415-sha-8542def9 sandbox or in an existing project with npx storybook@0.0.0-pr-33415-sha-8542def9 upgrade.

More information

Published version	0.0.0-pr-33415-sha-8542def9
Triggered by	@ndelangen
Repository	storybookjs/storybook
Branch	norbert/vitest-version-detection-fallback
Commit	8542def9
Datetime	Tue Dec 23 10:58:13 UTC 2025 (1766487493)
Workflow run	20458859104

To request a new release of this pull request, mention the @storybookjs/core team.

core team members can create a new canary release here or locally with gh workflow run --repo storybookjs/storybook publish.yml --field pr=33415

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View your CI Pipeline Execution ↗ for commit b83b026

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---

☁️ Nx Cloud last updated this comment at 2025-12-23 14:30:06 UTC

[storybook-app-bot]

Package Benchmarks

^{Commit: b83b026, ran on 23 December 2025 at 14:30:43 UTC}

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

@storybook/builder-webpack5

	Before	After	Difference
Dependency count	192	192	0
Self size	75 KB	75 KB	🎉 -48 B 🎉
Dependency size	32.17 MB	32.21 MB	🚨 +38 KB 🚨
Bundle Size Analyzer	Link	Link

@storybook/ember

	Before	After	Difference
Dependency count	196	196	0
Self size	15 KB	15 KB	🎉 -18 B 🎉
Dependency size	28.89 MB	28.93 MB	🚨 +38 KB 🚨
Bundle Size Analyzer	Link	Link

@storybook/nextjs

	Before	After	Difference
Dependency count	538	538	0
Self size	646 KB	646 KB	🚨 +120 B 🚨
Dependency size	59.11 MB	59.15 MB	🚨 +38 KB 🚨
Bundle Size Analyzer	Link	Link

@storybook/react-webpack5

	Before	After	Difference
Dependency count	278	278	0
Self size	24 KB	24 KB	🚨 +12 B 🚨
Dependency size	44.06 MB	44.10 MB	🚨 +38 KB 🚨
Bundle Size Analyzer	Link	Link

@storybook/server-webpack5

	Before	After	Difference
Dependency count	204	204	0
Self size	16 KB	16 KB	0 B
Dependency size	33.43 MB	33.47 MB	🚨 +38 KB 🚨
Bundle Size Analyzer	Link	Link

@storybook/preset-react-webpack

	Before	After	Difference
Dependency count	170	170	0
Self size	18 KB	18 KB	🎉 -24 B 🎉
Dependency size	31.20 MB	31.24 MB	🚨 +38 KB 🚨
Bundle Size Analyzer	Link	Link

[yannbf]

LGTM!