chore(action-button): migrate api and typescript code

[cdransf]

Description

Phase 3 of the swc-action-button 1st-gen → 2nd-gen washing machine migration. This PR migrates the public API and TypeScript to the 2nd-gen ActionButton class, adds runtime deprecation warnings to 1st-gen, and cleans up the structural artifact left by Phase 2 (removing the intermediate ActionButtonBase class from core so the package exports types only, as the migration plan specifies).

2nd-gen ActionButton.ts

• value promoted to a getter/setter pair. When the stored value is empty, textContent.trim() is used as the effective value, matching the 1st-gen identity contract for swc-action-group membership.
• aria-haspopup and aria-expanded forwarding: private @property fields observe those attributes on the host and forward them into the inner <button>, enabling popup disclosure patterns without a MutationObserver.
• @cssprop entries updated to use logical property names (--swc-action-button-min-block-size, --swc-action-button-border-radius); two incorrect entries (--swc-action-button-edge-to-text, --swc-action-button-edge-to-visual) removed.
• size override (added in structural fix) moves the full xs–xl range onto the SWC class via VALID_SIZES static, a getter/setter, and a _size backing field. An update() override counteracts SizedMixin's auto-reflect of size="m" for cases where no size was explicitly set.

1st-gen ActionButton.ts

• @deprecated JSDoc added to emphasized, hold-affordance, selected, and toggles.
• Runtime window.__swc.warn({ level: 'deprecation' }) calls added inside existing code paths in updated() for each deprecated property.

Structural fix (squashed from Phase 2 branch)

• Deleted ActionButton.base.ts from core/components/action-button/; the package now exports types only, matching the migration plan architecture table.
• ActionButton.ts (SWC) extends ButtonBase directly.

Motivation and context

This is Phase 3 of the action button migration as tracked in the 2nd-gen component migration workstream. The migration plan was merged in #6327 and the structural foundation was established in the Phase 2 PR.

The value getter/setter fallback and the aria-haspopup/aria-expanded forwarding are required for swc-action-group integration and popup disclosure patterns respectively; both are specified in the migration plan.

SWC-2043

Related issue(s)

• Depends on Phase 2 structural PR (branch cdransf/s2-action-button-migration-structure)

Screenshots (if appropriate)

N/A — TypeScript and API changes only; no visual output in this phase.

Author's checklist

• I have read the CONTRIBUTING and PULL_REQUESTS documents.
• I have reviewed 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.

Reviewer's checklist

• Includes a Github Issue with appropriate flag or Jira ticket number without a link
• Includes thoughtfully written changeset if changes suggested include patch, minor, or major features
• Automated tests cover all use cases and follow best practices for writing
• Validated on all supported browsers
• All VRTs are approved before the author can update Golden Hash

Manual review test cases

• value fallback behavior

  1. Render a <swc-action-button> with no value attribute set and text content "Edit"
  2. Read element.value in the console
  3. Expect "Edit" (falls back to textContent.trim())

• value explicit set

  1. Render a <swc-action-button value="edit-action">Edit</swc-action-button>
  2. Read element.value in the console
  3. Expect "edit-action" (explicit value takes precedence)

• aria-haspopup / aria-expanded forwarding

  1. Render <swc-action-button aria-haspopup="menu" aria-expanded="false">Open menu</swc-action-button>
  2. Inspect the inner <button> in DevTools
  3. Expect aria-haspopup="menu" and aria-expanded="false" present on the inner <button>

• Size attribute absent by default

  1. Render <swc-action-button>Edit</swc-action-button> with no size attribute
  2. Inspect the host element
  3. Expect no size attribute on the host (the SizedMixin workaround suppresses auto-reflect of size="m")

• 1st-gen deprecation warnings

  1. Enable debug mode (window.__swc = { DEBUG: true })
  2. Set emphasized, selected, toggles, or hold-affordance on a <sp-action-button>
  3. Expect a deprecation-level window.__swc.warn console message for each property

Device review

• Did it pass in Desktop?
• Did it pass in (emulated) Mobile?
• Did it pass in (emulated) iPad?

Accessibility testing checklist

• Keyboard (required — document steps below)

  1. Go to the swc-action-button Storybook stories (Playground story)
  2. Press Tab to move focus to the button; confirm focus ring is visible
  3. Press Enter or Space; confirm the button activates (click handler fires)
  4. Set disabled on the button; confirm it is no longer reachable via Tab
  5. Set aria-haspopup="menu" and aria-expanded="false" on the host; confirm focus and activation still work normally

• Screen reader (required — document steps below)

  1. Open the Playground story with VoiceOver (macOS) or NVDA (Windows)
  2. Tab to the button; confirm it is announced as "button" with its visible label
  3. With disabled set, confirm the button is announced as dimmed/unavailable
  4. With aria-haspopup="menu" and aria-expanded="false" set on the host, confirm the inner button is announced with "has popup, menu" and "collapsed"
  5. With pending set, confirm aria-disabled="true" and the pending accessible name are announced

[changeset-bot]

⚠️ No Changeset found

Latest commit: a711de4

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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

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[5t3ph]

[nit] My understanding is that AT would skip any ARIA that isn't compatible with the role. So since the host won't have the button role, these ARIA attributes also won't be doing any harm. What might be interesting is if having or not having them would cause issues with us testing relationships such as with Menu.

[cdransf]

Ah yeah, it will ignore those — stripping those attributes keeps the host clean for tooling and avoids any ambiguity if the host is given a role in the future. ✨