Search 3.0: add author to expanded results-list meta row (RSM-2999)

[kangzj]

Fixes RSM-2999

Why

Authors are a primary signal readers use to decide which result to click. Legacy Instant Search shows the post author in its expanded result card; Search 3.0's expanded jetpack-search/results-list block had dropped it. This PR brings that information back so site visitors and editors who migrate from Instant Search don't lose a familiar piece of context.

Proposed changes

• Normalize fields.author from the v1.3 Search API into a single authorLabel on each result. Single-author posts pass through as-is; co-authored posts comma-join (Instant Search's behaviour), and >3 authors truncate to the first three + "..." so the meta row doesn't run away.
• Add a show_author per-layout flag, enabled for the expanded layout only (compact and product unchanged).
• Render the author in the same .jetpack-search-results__meta row that holds the date — author first, then a · separator span, then the date. The separator is bound to data-wp-bind--hidden="!authorLabel || !dateLabel" so posts with only an author or only a date don't get a stray bullet.
• Mirror the markup in the editor preview (edit.js → renderExpandedPreview) so Gutenberg authors see the field in the inserter, including the multi-author and no-author edge cases.
• Restyle .jetpack-search-results__meta as a flex row with a 0.5rem gap and move the meta row's top margin off of the date span so the new author span doesn't get a stale top offset. Compact layout keeps its inline-with-title behaviour via a margin-top: 0 override.

Related product discussion/links

• RSM-2999

Does this pull request change what data or activity we track or use?

No.

Screenshots

Editor preview of the jetpack-search/results-list block in Expanded layout, captured locally via Playwright against the per-agent docker WordPress at 1440×900.

Before (trunk)	After

Notice the third sample row in the After image — it intentionally has no author, and the · separator is suppressed.

Testing instructions

Acceptance criteria from RSM-2999, in checklist form:

• In a post/page containing a jetpack-search/results-list block in Expanded layout, a result with a single author shows that author in the meta row, before the date, separated by a ·.
• A result with co-authors (2 or 3) shows their names comma-joined in the same meta row.
• A result with more than 3 co-authors shows the first three joined with commas and a trailing "..." (e.g. Ada, Bob, Cris...).
• A result with no author renders only the date — no stray · separator and no empty author span.
• Compact and Product layouts are unchanged (author is suppressed; meta row visual matches trunk).
• In the block editor, opening the Inserter preview for the Expanded layout shows the same author treatment via the sample data (Sample Author, A. Writer, B. Editor, and an author-less third row).

[github-actions]

Are you an Automattician? Please test your changes on all WordPress.com environments to help mitigate accidental explosions.

• To test on WoA, go to the Plugins menu on a WoA dev site. Click on the "Upload" button and follow the upgrade flow to be able to upload, install, and activate the Jetpack Beta plugin. Once the plugin is active, go to Jetpack > Jetpack Beta, select your plugin (Jetpack), and enable the nova/rsm-2999-author-expanded-layout branch.
• To test on Simple, run the following command on your sandbox:

bin/jetpack-downloader test jetpack nova/rsm-2999-author-expanded-layout

Interested in more tips and information?

• In your local development environment, use the jetpack rsync command to sync your changes to a WoA dev blog.
• Read more about our development workflow here: PCYsg-eg0-p2
• Figure out when your changes will be shipped to customers here: PCYsg-eg5-p2

[github-actions]

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[jp-launch-control]

Code Coverage Summary

Coverage changed in 2 files.

File	Coverage	Δ%	Δ Uncovered
projects/packages/search/src/search-blocks/blocks/results-list/render.php	270/270 (100.00%)	0.00%	0 💚
projects/packages/search/src/search-blocks/store/result-utils.js	116/116 (100.00%)	0.00%	0 💚

Full summary · PHP report · JS report

[kangzj]

🤖 Review-cycle summary — 123a57db22a → 88cbc2a1be5

4 round(s); CI green; 1 thread resolved; 2 AI reviewers (Copilot + claude[bot]) addressed.

What changed during the cycle

Commits added:

• 44cd5c6c664 — Address review: request author from API + decode HTML entities in formatAuthor (comments #3230642237, claude[bot] review)
• 88cbc2a1be5 — Address review: fix stale test fixture + name for authorLabel exposure (claude[bot] re-review)

Diff summary: 4 files changed, 29 insertions(+), 8 deletions(-)

Review threads addressed:

Source	Comment	Resolution
Copilot (inline)	result-utils.js:445 — authorLabel derived but author wasn't in SEARCH_FIELDS, so it would always be empty at runtime.	Added 'author' to SEARCH_FIELDS; flipped the api.test.js assertion to require it. Resolved in 44cd5c6c664.
claude[bot] (review)	formatAuthor doesn't call decodeEntities; names like O’Brien would render literally via data-wp-text.	Wired both string and array paths through decodeEntities; added a test case for numeric/named entity coverage. Resolved in 44cd5c6c664.
claude[bot] (re-review)	Stale test at result-utils.test.js:699 had a dotted fixture ('author.name') and a name that read as a prohibition of behavior the PR now provides.	Renamed test, swapped fixture to the real author field, added explicit authorLabel === 'Ada Lovelace' assertion. Resolved in 88cbc2a1be5.

Unaddressed (flagged for owner): None.

CI: all required checks passing.