fix(polymorphic): Improve prop passthrough for ActionList.LinkItem and Breadcrumbs.Item

[hussam-i-am]

• Resolves https://github.com/github/primer/issues/6470

Changelog

New

Changed

• Updates typing for Breadcrumbs.Item to allow passthrough props when using as
• Updates typing for ActionList.LinkItem to allow passthrough props when using as
• Fixes Breadcrumsb overflow
• Adds tests for ActionList.LinkItem

Removed

Rollout strategy

• Patch release
• Minor release
• Major release; if selected, include a written rollout or migration plan
• None; if selected, include a brief description as to why

Testing & Reviewing

Merge checklist

• Added/updated tests
• Added/updated documentation
• Added/updated previews (Storybook)
• Changes are SSR compatible
• Tested in Chrome
• Tested in Firefox
• Tested in Safari
• Tested in Edge
• (GitHub staff only) Integration tests pass at github/github-ui (Learn more about how to run integration tests)

[changeset-bot]

🦋 Changeset detected

Latest commit: 5d1ff4e

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@primer/react	Minor

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[github-actions]

⚠️ Action required

👋 Hi, this pull request contains changes to the source code that github/github-ui depends on. If you are GitHub staff, test these changes with github/github-ui using the integration workflow. Check the integration testing docs for step-by-step instructions. Or, apply the integration-tests: skipped manually label to skip these checks.

[primer]

🤖 Lint issues have been automatically fixed and committed to this PR.

[primer]

🤖 Lint issues have been automatically fixed and committed to this PR.

[Copilot]

Pull request overview

Improves Primer React’s polymorphic typing so as-specified components receive correct passthrough props, targeting ActionList.LinkItem and Breadcrumbs.Item (and updating NavList.Item, which wraps ActionList.LinkItem) to address issue #6470.

Changes:

• Migrates ActionList.LinkItem, Breadcrumbs.Item, and NavList.Item to modern-polymorphic (PolymorphicProps + fixedForwardRef) for better as prop passthrough typing.
• Updates Breadcrumbs overflow-menu rendering to forward as + extra props into overflow menu items.
• Adds unit tests covering polymorphic passthrough for ActionList.LinkItem, NavList.Item, and Breadcrumbs.Item (including overflow menu case).

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
packages/styled-react/src/components/ActionList.tsx	Simplifies styled wrapper typing for ActionList.LinkItem in the legacy styled-components package.
packages/react/src/NavList/NavList.tsx	Updates NavList.Item to modern polymorphic typing and forwards as into ActionList.LinkItem.
packages/react/src/NavList/NavList.test.tsx	Adds coverage for NavList.Item passthrough props when using as.
packages/react/src/Breadcrumbs/Breadcrumbs.tsx	Updates Breadcrumbs.Item typing and forwards as/props into overflow menu rendering.
packages/react/src/Breadcrumbs/tests/Breadcrumbs.test.tsx	Adds tests for polymorphic Breadcrumbs.Item and overflow menu passthrough behavior.
packages/react/src/ActionList/LinkItem.tsx	Updates ActionList.LinkItem to modern polymorphic typing and preserves slot marker metadata.
packages/react/src/ActionList/LinkItem.test.tsx	Adds initial unit tests for ActionList.LinkItem, including as passthrough.
.changeset/curly-moments-show.md	Declares a minor release for the typing/passthrough improvement.

[primer-integration]

👋 Hi from github/github-ui! Your integration PR is ready: https://github.com/github/github-ui/pull/16126

[primer-integration]

Integration test results from github/github-ui:

  CI Passed
  VRT Passed
  Projects Passed

All checks passed!