chore(swc): upgrade Storybook to 10.4.1 and Vitest to 4.1.7

[rubencarvalho]

Description

Upgrades Storybook and Vitest to their latest versions, and fixes two issues in the Storybook dev server: the coverage report link returning 404, and a startup warning about an unmatched story glob.

Package versions bumped

Package	Before	After
storybook	10.3.5	10.4.1
@storybook/addon-a11y	10.3.5	10.4.1
@storybook/addon-docs	10.3.5	10.4.1
@storybook/addon-vitest	10.3.5	10.4.1
@storybook/web-components-vite	10.3.5	10.4.1
@storybook/test-runner	0.24.3	0.24.4
@chromatic-com/storybook	5.0.1	5.2.1
@wc-toolkit/storybook-helpers	10.2.3	10.3.0
vitest	4.0.15	4.1.7
@vitest/browser	4.0.15	4.1.7
@vitest/browser-playwright	4.0.15	4.1.7
@vitest/coverage-v8	4.0.15	4.1.7
@vitest/ui	4.0.15	4.1.7

Yarn patches ported

Two existing patches were carried forward to the new package versions (neither bug is fixed upstream):

• storybook autoplay patch: Prevents play functions from running on initial story load when parameters.autoplay is not explicitly true. Without this, stories auto-run their play function on first render, which can interfere with how docs and overview stories appear.
• @wc-toolkit/storybook-helpers cssProperties patch: Suppresses a block that adds all CSS custom properties to the Storybook controls table with table: { disable: true }, which caused redundant hidden entries to appear in the controls panel.

Coverage report now accessible in the dev server

Clicking the coverage link in Storybook's Vitest panel previously opened http://localhost:6006/coverage/index.html and returned Not Found. The coverage/ directory is now mapped as a static dir in .storybook/main.ts, but only when the directory already exists (guarded with existsSync) so starting Storybook before running coverage does not produce an error.

To use: run yarn test:coverage first, then start Storybook. The coverage link will resolve correctly.

Startup warning removed

Removed a story glob pattern (../core/**/stories/**/*.test.ts) that matched no files, which produced a ▲ No story files found warning on every dev server start. It's being fixed here: #6341

Motivation and context

Routine dependency maintenance to stay current with Storybook and Vitest releases, plus fixes for two developer experience issues surfaced during local development.

Related issue(s)

N/A

Author's checklist

• I have read the CONTRIBUTING and PULL_REQUESTS documents.
• I have reviewed at the Accessibility Practices for this feature, see: Aria Practices
• I have added automated tests to cover my changes.
• I have included a well-written changeset if my change needs to be published.
• I have included updated documentation if my change required it.

Accessibility testing checklist

This is a dependency upgrade with no changes to component behavior, markup, or ARIA implementation. No accessibility testing is required.

• Keyboard: No interactive changes; no keyboard testing required.
• Screen reader: No markup or ARIA changes; no screen reader testing required.

[changeset-bot]

⚠️ No Changeset found

Latest commit: ed18ea5

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[github-actions]

📚 Branch Preview Links

• Documentation Site (first-gen)
• Storybook (first-gen)
• Storybook (second-gen)

🔍 First Generation Visual Regression Test Results

When a visual regression test fails (or has previously failed while working on this branch), its results can be found in the following URLs:

• Spectrum | Light | Medium | LTR
• Spectrum | Dark | Large | RTL
• Express | Light | Medium | LTR
• Express | Dark | Large | RTL
• Spectrum-two | Light | Medium | LTR
• Spectrum-two | Dark | Large | RTL
• High Contrast Mode | Medium | LTR

Deployed to Azure Blob Storage: pr-6343

If the changes are expected, update the current_golden_images_cache hash in the circleci config to accept the new images. Instructions are included in that file.
If the changes are unexpected, you can investigate the cause of the differences and update the code accordingly.

[caseyisonit]

i dont understand why the formatting is changing it so the end bracket is starting the new line. Im not sure why this would be getting picked up in a version bump PR? is there a side effect to this?

[rubencarvalho]

AAAARRRR i've been getting this file change locally every time and I accidentally committed it. i need to investigate this! - I'll remove it for now

[caseyisonit]

do we want to bump to 100? im fine with it but we might need to check this against whats in the system currently?

[rubencarvalho]

ooops this also got accidentally committed. we currently have a setting that rewrites this baseline to the current value whenever we run the coverage checks. I'll revert it because it's out of scope of this PR

[rubencarvalho]

This is fixed in #6341