Add ActionBar.Button for text button overflow support

[Copilot]

ActionBar only supported IconButton children; text buttons (now common in GH design) had no first-class API and no overflow handling. This adds ActionBar.Button, used like ActionBar.IconButton, that collapses into the overflow menu when space runs out.

<ActionBararia-label="Toolbar"><ActionBar.Button>Save</ActionBar.Button><ActionBar.ButtonleadingVisual={SearchIcon}>Search</ActionBar.Button><ActionBar.Divider/><ActionBar.Buttondisabled>Cancel</ActionBar.Button></ActionBar>

Changelog

New

• ActionBar.Button — a text Button subcomponent (variant="invisible") that registers with the existing overflow mechanism. Uses children as the overflow menu label and forwards a component leadingVisual as the menu item's leading icon.
• Exported ActionBarButtonProps.
• Storybook example WithTextButtons; docs metadata; unit tests.

Changed

• Overflow action items now render a leading visual only when an icon is present (text buttons may have none); item key switched from label to the registry id. Internally, the actionChildPropsicon is now optional and label accepts ReactNode.

Removed

• N/A

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

Additive, backwards-compatible API.

Testing & Reviewing

Storybook → Experimental/Components/ActionBar/Examples → WithTextButtons. Resize the container to verify buttons overflow into the menu, the label (and optional leading icon) render in the menu, and disabled is respected. Unit coverage added in ActionBar.test.tsx (render, click, disabled, keyboard).

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: 2319701

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. If this doesn't work, you can also use the original workflow here. Check the integration testing docs for step-by-step instructions. Or, apply the integration-tests: skipped manually label to skip these checks.

To publish a canary release for integration testing, apply the Canary Release label to this PR.

[primer-integration]

Integration test results from github/github-ui PR:

CI Failed
VRT Passed
Projects Passed

CI check runs linting, type checking, and unit tests. Check the workflow logs for specific failures.

Need help? If you believe this failure is unrelated to your changes, please reach out to the Primer team for assistance.

[iansan5653]

skipping integration because there is a breaking typecheck but it's not related to this PR

[Copilot]

Pull request overview

Adds a first-class ActionBar.Button subcomponent (text Button variant) that participates in the existing ActionBar overflow registry, enabling text buttons to collapse into the overflow menu alongside ActionBar.IconButton.

Changes:

• Introduces ActionBar.Button + exported ActionBarButtonProps, and wires it into ActionBar’s static API.
• Updates overflow menu rendering for action items to support optional leading visuals and uses registry id for React keys.
• Adds Storybook example, docs metadata, tests, snapshot update, and a minor-release changeset.

Show a summary per file

File	Description
packages/react/src/ActionBar/index.ts	Exposes ActionBar.Button and re-exports ActionBarButtonProps.
packages/react/src/ActionBar/ActionBar.tsx	Implements ActionBarButton, updates registry item shape and overflow menu rendering.
packages/react/src/ActionBar/ActionBar.test.tsx	Adds unit coverage for ActionBar.Button behavior and attributes.
packages/react/src/ActionBar/ActionBar.examples.stories.tsx	Adds WithTextButtons example for overflow behavior.
packages/react/src/ActionBar/ActionBar.docs.json	Documents ActionBar.Button props and passthrough.
packages/react/src/tests/snapshots/exports.test.ts.snap	Updates export snapshot to include ActionBarButtonProps.
.changeset/actionbar-text-button.md	Declares a minor bump for the new exported API.

Copilot's findings

• Files reviewed: 7/7 changed files
• Comments generated: 2