feat(infield-button): Phase 2 — file structure, API, TypeScript, and accessibility

[Rajdeepc]

Description

Scaffolds the 2nd-gen infield-button component for Phase 2 of the 1st-gen → 2nd-gen component migration. This PR creates the core and SWC file structure, establishes the base class architecture, and wires the package exports so the element is importable — but contains no production styling (that comes in Phase 5).

Motivation and context

Infield buttons are embedded inside form fields (e.g. number-field increment/decrement controls). Their migration has specific architectural constraints captured in the migration plan:

• Non-focusable by design: Infield buttons are pointer-only. They are not in the tab order and not independently keyboard-focusable. The parent field owns all keyboard behavior and the visible focus ring. This is implemented by setting delegatesFocus: false on the shadow root and tabindex="-1" on the inner <button>.
• Parent-delegated sizing: No default size is assumed. The parent field always sets the size attribute. Valid sizes are s, m, l, xl.
• Quiet property on the base class: The quiet attribute reflects to the host for CSS :host([quiet]) targeting in Phase 5.
• Core/SWC split: InfieldButtonBase lives in core so other form-field components can extend it without inheriting the SWC visual surface.

Related issue(s)

• fixes SWC-2108

Screenshots (if appropriate)

N/A — scaffold only, no visual output yet.

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.

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

• InfieldButtonBase extends ButtonBase correctly; VALID_SIZES restricted to ['s','m','l','xl']

  1. Import InfieldButtonBase from @spectrum-web-components/core/components/infield-button
  2. Confirm InfieldButtonBase.VALID_SIZES equals ['s','m','l','xl']
  3. Confirm InfieldButtonBase.shadowRootOptions.delegatesFocus is false

• Element registers and renders without errors

  1. Import @adobe/spectrum-wc/components/infield-button/swc-infield-button.js
  2. Place <swc-infield-button accessible-label="Increment" size="m"><sp-icon-chevron100 slot="icon"></sp-icon-chevron100></swc-infield-button> in the DOM
  3. Confirm the element renders with an inner <button tabindex="-1">
  4. Confirm Tab does not focus the button

• quiet attribute reflects to host

  1. Set quiet property to true on the element
  2. Confirm [quiet] attribute is present on the host element

Device review

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

Accessibility testing checklist

This PR scaffolds the structural foundation only. No user-facing interaction surface is added beyond what is already covered by ButtonBase. Full accessibility testing will occur in Phase 4 (migration-a11y).

• Keyboard — infield buttons intentionally have tabindex="-1" on the inner <button> and delegatesFocus: false on the shadow root. They must not be reachable via Tab. The parent field owns keyboard behavior.
• Screen reader — accessible-label is forwarded to aria-label on the inner <button> via the inherited ButtonBase binding. Phase 4 will verify the full announcement behavior in context.

[changeset-bot]

⚠️ No Changeset found

Latest commit: 131388f

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

When changesets are added to this PR, you'll see the packages that this PR includes changesets for and the associated semver types

Click here to learn what changesets are, and how to add one.

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

[github-actions]

📚 Branch Preview Links

• Storybook (Gen2, dev mode)
• Storybook (Gen2, prod mode)
• Documentation Site (Gen1)
• Storybook (Gen1)

🔍 Gen1 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-6498

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.

[nikkimk]

lgtm