chore(close-button): migration guide

[TarunAdobe]

Description

• Adds the close-button Phase 1 planning artifacts under CONTRIBUTOR-DOCS:
  • CONTRIBUTOR-DOCS/03_project-planning/03_components/close-button/migration-plan.md
  • CONTRIBUTOR-DOCS/03_project-planning/03_components/close-button/rendering-and-styling-migration-analysis.md
• Removes the previously added consumer-facing guide:
  • 2nd-gen/packages/swc/components/close-button/migration-guide.mdx
• Updates CONTRIBUTOR-DOCS/03_project-planning/03_components/README.md to index the new close-button plan + roadmap docs.
• Captures confirmed design inputs in the plan/docs:
  • S2 Web Desktop Figma node for close button
  • S2 close-button anatomy doc
  • spectrum-css spectrum-two closebutton source

Motivation and context

This work corrects scope and artifact type for the close-button epic.
The prior MDX was consumer migration documentation, but this stage requires internal migration planning docs (washing-machine Phase 1 style) before implementation.

This PR establishes the review surface for:

• 1st-gen API inventory
• must-ship vs additive migration scope
• core vs SWC architecture direction
• sequencing/checklist for setup → API → styling → a11y → testing → docs → review

Related issue(s)

• Epic SWC-2087 — Close button migration
• SWC-2088 — Accessibility recommendations (already documented)
• SWC-2089 — Analyze component and create migration plan (this PR)

Screenshots (if appropriate)

• N/A (documentation-only change)

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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.

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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

• Verify close-button migration planning docs were added and consumer guide was removed

  1. Open migration plan and migration roadmap
  2. Confirm both files exist and contain close-button-specific content
  3. Confirm 2nd-gen/packages/swc/components/close-button/migration-guide.mdx is removed

• Verify phase-1 planning scope and design references

  1. In migration-plan.md, review TL;DR, Changes overview, Migration checklist, and Blockers and open questions
  2. Confirm the Figma link, S2 anatomy link, and spectrum-css closebutton source are present
  3. Confirm the plan captures must-ship and additive items plus core/SWC split

• Verify contributor docs index was updated

  1. Open components README
  2. Under Close Button, confirm links exist for:
     • close-button accessibility migration analysis
     • close-button migration plan
     • close-button migration roadmap

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. N/A for this PR (documentation-only; no runtime UI behavior changed)
  2. —
  3. —

• Screen reader (required — document steps below)

  1. N/A for this PR (documentation-only; no runtime UI behavior changed)

[changeset-bot]

⚠️ No Changeset found

Latest commit: 677bf18

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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

Deployed to Azure Blob Storage: pr-6322

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.

[cdransf]

Suggested change

	- [Q2](#architecture-and-behavior): Confirm whether `icon-size` should be a public API in SWC or kept internal.
	- [Q1](#architecture-and-behavior): Confirm whether `icon-size` should be a public API in SWC or kept internal.

[cdransf]

Should these be formatted as a table? https://github.com/adobe/spectrum-web-components/blob/main/.ai/skills/migration-prep/assets/migration-prep-template.md#blockers-and-open-questions ✨

[cdransf]

Should deprecation information be in the API table and breaking changes section? ✨