Fix ActionMenu bugs

[rezrah]

Summary

Fixes multiple issues in the ActionMenu component.

Fixes #1372
Fixes #1366
Fixes #1397

List of notable changes:

• Adds variant rendering of non-split action menu. Now supports all Button variants, previously ignored
• Adds rendering of the leadingVisual in non-split action menu, previously ignored
• Adds onClick forwarding to non-split action menu, previously ignored
• Updates data-attribute forwarding to correct child component

What should reviewers focus on?

• Check the stories and code.
• Are we happy to allow ActionMenu default mode button to appear in different colors? This was intentionally unavailable before.

Steps to test:

1. See non-split ActionMenu in different colors here
2. See leadingVisual in non-split ActionMenu here.
3. Generally review all stories. Non-visual changes are validated through tests.

Contributor checklist:

• All new and existing CI checks pass
• Tests prove that the feature works and covers both happy and unhappy paths
• Any drop in coverage, breaking changes or regressions have been documented above
• UI Changes contain new visual snapshots (generated by adding update snapshots label to the PR)
• All developer debugging and non-functional logging has been removed
• Related issues have been referenced in the PR description

Reviewer checklist:

• Check that pull request and proposed changes adhere to our contribution guidelines and code of conduct
• Check that tests prove the feature works and covers both happy and unhappy paths
• Check that there aren't other open Pull Requests for the same update/change

Screenshots:

Please try to provide before and after screenshots or videos

Leading visual

Before	After
N/A

Alternative variants

Before	After
N/A

[changeset-bot]

🦋 Changeset detected

Latest commit: 8420c03

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

This PR includes changesets to release 9 packages

Name	Type
@primer/react-brand	Minor
@primer/brand-docs	Minor
@primer/brand-css	Minor
@primer/brand-primitives	Minor
@primer/brand-e2e	Minor
@primer/brand-fonts	Minor
@primer/brand-mcp	Minor
@primer/brand-config	Minor
@primer/brand-storybook	Minor

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[github-actions]

🟢 No design token changes found

[github-actions]

🟢 Bundle size report

Check	Main	Branch	Change
UMD — full bundle (JS)	101.47 kB	101.39 kB	✅ -81 B (-0.1%)
UMD — full bundle (CSS)	66.92 kB	66.92 kB	🟢 No change
ESM — full bundle (JS + CSS)	1.51 MB	1.51 MB	⬆️ +112 B (+0.0%)
ESM — tree-shaken simple (Button)	69.81 kB	69.81 kB	🟢 No change
ESM — tree-shaken complex (ActionMenu)	78.59 kB	78.70 kB	⬆️ +116 B (+0.1%)

[github-actions]

🟢 No visual differences found

Our visual comparison tests did not find any differences in the UI.

[Copilot]

Pull request overview

This PR fixes several ActionMenu.Button inconsistencies/bugs so that default mode behaves more like split-button mode (variant/leadingVisual support and click forwarding), and so split-button mode forwards consumer attributes to the intended (“primary action”) button. It also adds Storybook coverage plus unit/visual tests and a changeset entry.

Changes:

• Forward variant and leadingVisual to the default-mode Button, and forward/correct onClick + menu toggle behavior.
• Correct attribute forwarding in split-button mode so consumer attributes apply to the primary action (not the menu toggle).
• Add/extend unit tests, visual snapshot coverage, and Storybook feature stories for the fixed behaviors.

Show a summary per file

File	Description
packages/react/src/ActionMenu/ActionMenu.tsx	Adds menu-toggle callback plumbing and updates ActionMenu.Button rendering/prop forwarding in default and split-button modes.
packages/react/src/ActionMenu/ActionMenu.test.tsx	Adds unit tests covering default-mode onClick + toggle, default-mode variant/leadingVisual, and split-button attribute/onClick separation.
packages/react/src/ActionMenu/ActionMenu.visual.spec.ts	Adds visual snapshots for the new default-mode variant + leadingVisual stories.
packages/react/src/ActionMenu/ActionMenu.features.stories.tsx	Adds new feature stories to demonstrate default-mode variant rendering and leadingVisual rendering.
.changeset/fix-action-menu-split-button-click.md	Documents the user-visible changes and the split-button attribute forwarding behavior change.

Review details

• Files reviewed: 5/7 changed files
• Comments generated: 3
• Review effort level: Low

[github-actions]

🟢 Unit test coverage changes found

Unit test coverage has been updated through this PR.

Changes: 0 new tests, 0 removed tests, 1 improved, 0 decreased

Component/Hook	Statements	Functions	Branches	Change
ActionMenu	94.4% 94.6%	89.7% 90.0%	87.4% 87.7%	+0.3%

[danielguillan]

This looks great! Thank you for the fixes. We only need to update the React documentation to include the newly supported variant in the props table and revise the split-button guidance. 🚀