feat(research): equal-contribution and PI superscript markers

Extends the conditional sup system in HeadingResearch beyond the existing
`*` (corresponding) + numeric affiliation indices to cover the two other
academic conventions that come up on multi-author papers:

  †  Equal contribution    — `equalContribution: true`
  ‡  Principal investigator — `principalInvestigator: true`

Both new fields are optional booleans on the Author type. Existing
entries are unaffected.

Suppression rules (each marker only renders when it disambiguates):
  *  shows when 2+ authors AND ≥1 corresponding
  †  shows when 2+ authors AND ≥2 flagged equal-contribution (a single
     "equal" author is meaningless)
  ‡  shows when 2+ authors AND ≥1 PI
  ¹² shows when 2+ affiliations

Marker order on each author follows academic typesetting convention:
symbol markers (*†‡) first, then numeric affiliation indices. Each <sup>
keeps its cursor-help + native title tooltip ("Corresponding author",
"Equal contribution", "Principal investigator", or the resolved
affiliation name).

The previous standalone "*Corresponding author" caption is replaced by a
single combined caption line that stacks all active markers separated by
` · ` — e.g. "*Corresponding author · †Equal contribution · ‡Principal
investigator" — kept tight and rendered only when at least one symbol
marker is showing.

Documented the new flags + the combined caption behavior in CLAUDE.md
and README.md (research-authoring section now has a flag/glyph/rule
table). Frontmatter example shows the two new fields commented out so a
fork sees them and can opt in.

Verified locally: yarn type-check, yarn lint, yarn test (48/48),
yarn build (50 routes) — all clean.

Author: ahnafnafee

CLAUDE.md

@@ -128,7 +128,13 @@ ISR endpoint at `GET /api/revalidate?secret=<SECRET>&slug=/blog/<slug>`. Secret
 - Frontmatter `published` for blog and research is `MM/DD/YYYY` (portfolio uses `date`). `featured: true` surfaces an entry on the home page. Optional `updated: "MM/DD/YYYY"` overrides `published` as the freshness signal — it flows into `dateModified` (BlogPosting / ScholarlyArticle JSON-LD), `<meta property="article:modified_time">`, and the sitemap `lastmod`. Set it whenever you make a substantive content edit; leave it off for typo fixes.
 - Authoring convention: open every blog post with a 60–120 word TL;DR paragraph immediately under the H1. LLM crawlers (ChatGPT, Perplexity, AI Overviews) draw ~44% of their citations from the first 30% of an article, so front-loading the answer compounds visibility.
 - **Research authoring**: use the YAML folded scalar (`abstract: >-`) — block scalar (`|`) preserves newlines and the abstract renders with broken lines. Authors use a structured array; `affiliations` indices are 1-based and reference the entry's `affiliations` array. `section` drives listing-page grouping (`top-tier` / `conferences` / `journals` / `workshops` / `others`). `new: true` renders a NEW badge inline with the title on the listing card. `comingSoon: true` swaps the listing thumbnail for the `ComingSoonImage` pastel placeholder (no thumbnail/teaser required). Authors matching `SITE_AUTHOR.name` are auto-bolded across `HeadingResearch` and `ResearchItem`.
-- **Author / affiliation superscripts** in `HeadingResearch` are conditional: `*` (corresponding author) only renders when there are 2+ authors AND at least one is `corresponding: true`; `¹ ² ³` (affiliation indices) only render when there are 2+ affiliations. The affiliation legend below the author line drops its leading `<sup>` under the same rule. Single-author / single-affiliation entries collapse to clean text — no orphan markers. When markers do render, each `<sup>` has `cursor-help` and a native `title` tooltip explaining what it means (resolves to the affiliation's full name for index sups, "Corresponding author" for the asterisk). A "\*Corresponding author" caption appears below the affiliation line when the asterisk is shown.
+- **Author / affiliation superscripts** in `HeadingResearch` are conditional. Each marker only renders when it actually disambiguates something:
+  - `*` (corresponding author) — `corresponding: true` on the author. Shows when **2+ authors** AND at least one is corresponding.
+  - `†` (equal contribution) — `equalContribution: true` on the author. Shows when **2+ authors** AND at least 2 are flagged. Renders on every flagged author.
+  - `‡` (principal investigator) — `principalInvestigator: true` on the author. Shows when **2+ authors** AND at least one is PI.
+  - `¹ ² ³` (affiliation indices) — derived from `affiliations: [...]` on each author. Shows when **2+ affiliations** exist on the entry.
+
+  Marker order on each author follows academic convention: `*†‡` then numeric indices. The affiliation legend below the author line drops its leading `<sup>` under the same `showAffSup` rule. Single-author / single-affiliation entries collapse to clean text — no orphan markers. Each `<sup>` has `cursor-help` + a native `title` tooltip (affiliation index sups resolve to the full affiliation name; symbol sups resolve to their caption text). A combined caption line appears below the affiliation row when any symbol marker is shown — e.g. `*Corresponding author · †Equal contribution · ‡Principal investigator` — joined by ` · `.
 
 ## Indexing Helper
 

README.md

@@ -337,6 +337,8 @@ authors:
     email: 'aannafee@gmu.edu'
     affiliations: [1] # 1-based indices into the entry's affiliations array
     corresponding: true
+    # equalContribution: true       # OPTIONAL: → † on each flagged author + a "†Equal contribution" caption
+    # principalInvestigator: true   # OPTIONAL: → ‡ on PI + a "‡Principal investigator" caption
 affiliations:
   - name: 'George Mason University'
     location: 'Fairfax, Virginia, USA'
@@ -375,7 +377,16 @@ bibtex: |
 
 The detail page renders the structured fields in the hero (status chip from `venue.status`, authors with affiliation superscripts, venue line, action-button row driven by `links` and `bibtex`). Authors matching `SITE_AUTHOR.name` are bolded. The `bibtex` field renders as a copy-to-clipboard code block anchored at `#bibtex`.
 
-**Author / affiliation superscripts are conditional**: `*` (corresponding author) only renders when there are 2+ authors and at least one is `corresponding: true`; `¹ ² ³` (affiliation indices) only render when there are 2+ affiliations. Single-author / single-affiliation entries skip both — no orphan markers. When the markers do show, they carry hover tooltips (native `title` + `cursor-help`) that resolve to the actual affiliation names so the meaning is clear without scrolling.
+**Author / affiliation superscripts are conditional** — each marker only renders when it actually disambiguates something:
+
+| Flag on `Author`              | Glyph   | Caption                 | Renders when                    |
+| ----------------------------- | ------- | ----------------------- | ------------------------------- |
+| `corresponding: true`         | `*`     | \*Corresponding author  | 2+ authors AND ≥1 corresponding |
+| `equalContribution: true`     | `†`     | †Equal contribution     | 2+ authors AND ≥2 flagged equal |
+| `principalInvestigator: true` | `‡`     | ‡Principal investigator | 2+ authors AND ≥1 PI            |
+| `affiliations: [n]`           | `¹ ² ³` | _(legend below)_        | 2+ affiliations on the entry    |
+
+Marker order on each author: `*†‡` then numeric affiliation indices (academic convention). Single-author / single-affiliation entries skip everything — no orphan markers. When markers do show, each `<sup>` carries a native `title` tooltip (affiliation index sups resolve to the full affiliation name; symbol sups resolve to their caption). A combined caption line — e.g. `*Corresponding author · †Equal contribution · ‡Principal investigator` — auto-renders below the affiliation row.
 
 The research listing page (`/research`) renders an Overview paragraph, a date-column News timeline, and a colored chip row of Research Areas above the section-grouped listings. Section headings across the page (Overview / News / Research Areas / Top-Tier Venues / Conferences / Journals / Workshops / Others) share a single `<SectionHeading>` component (`text-lg md:text-xl`, `font-bold`, `text-black dark:text-white`, bordered bottom).
 

src/components/content/research/HeadingResearch.tsx

@@ -4,6 +4,7 @@ import { SITE_AUTHOR } from '@/libs/constants/site'
 import { twclsx } from '@/libs/twclsx'
 
 import { Affiliation, Author, ResearchLinks, Venue } from 'me'
+import { Fragment } from 'react'
 import {
   HiGlobeAlt,
   HiOutlineDatabase,
@@ -100,12 +101,23 @@ export const HeadingResearch: React.FunctionComponent<HeadingResearchProps> = (p
         </div>
       )}
 
-      {/* Suppress meaningless markers: only show affiliation superscripts when there are 2+ affiliations,
-          and only show the corresponding-author asterisk when there are 2+ authors. Otherwise the markers
-          are noise on a single-author / single-affiliation paper. */}
+      {/* Suppress meaningless markers: each superscript only renders when it actually
+          disambiguates something. Single-author / single-affiliation entries collapse
+          to clean text. Marker order on each author follows academic convention:
+          symbol markers (* † ‡) first, then numeric affiliation indices. */}
       {(() => {
+        const hasMultipleAuthors = props.authors.length > 1
+        const equalContribCount = props.authors.filter((a) => a.equalContribution).length
+
         const showAffSup = (props.affiliations?.length ?? 0) > 1
-        const showCorrespondingSup = props.authors.length > 1 && props.authors.some((a) => a.corresponding)
+        const showCorrespondingSup = hasMultipleAuthors && props.authors.some((a) => a.corresponding)
+        const showEqualContribSup = hasMultipleAuthors && equalContribCount >= 2
+        const showPISup = hasMultipleAuthors && props.authors.some((a) => a.principalInvestigator)
+
+        const captions: { glyph: string; label: string }[] = []
+        if (showCorrespondingSup) captions.push({ glyph: '*', label: 'Corresponding author' })
+        if (showEqualContribSup) captions.push({ glyph: '†', label: 'Equal contribution' })
+        if (showPISup) captions.push({ glyph: '‡', label: 'Principal investigator' })
 
         return (
           <>
@@ -147,6 +159,16 @@ export const HeadingResearch: React.FunctionComponent<HeadingResearchProps> = (p
                         *
                       </sup>
                     )}
+                    {author.equalContribution && showEqualContribSup && (
+                      <sup className={twclsx(nameClass, 'cursor-help')} title='Equal contribution'>
+                        †
+                      </sup>
+                    )}
+                    {author.principalInvestigator && showPISup && (
+                      <sup className={twclsx(nameClass, 'cursor-help')} title='Principal investigator'>
+                        ‡
+                      </sup>
+                    )}
                     {supText && showAffSup && (
                       <sup className={twclsx(nameClass, 'cursor-help')} title={affTitle || undefined}>
                         {supText}
@@ -185,9 +207,17 @@ export const HeadingResearch: React.FunctionComponent<HeadingResearchProps> = (p
               </p>
             )}
 
-            {showCorrespondingSup && (
+            {captions.length > 0 && (
               <p className={twclsx('mt-1 text-center text-xs text-gray-500 dark:text-gray-400')}>
-                <sup>*</sup>Corresponding author
+                {captions.map((cap, i) => (
+                  <Fragment key={cap.glyph}>
+                    {i > 0 && <span aria-hidden='true'>{' · '}</span>}
+                    <span>
+                      <sup>{cap.glyph}</sup>
+                      {cap.label}
+                    </span>
+                  </Fragment>
+                ))}
               </p>
             )}
           </>

src/types/index.d.ts

@@ -43,7 +43,16 @@ declare module 'me' {
     name: string
     url?: string
     affiliations?: Array<number>
+    /** Renders a `*` superscript next to the name + a "*Corresponding author" caption.
+     * Suppressed on single-author papers (the marker has nothing to disambiguate). */
     corresponding?: boolean
+    /** Marks shared first-authorship. Renders a `†` superscript on every author with the
+     * flag set + a "†Equal contribution" caption. Requires at least 2 authors flagged
+     * (the concept of "equal" is meaningless with one). */
+    equalContribution?: boolean
+    /** Marks the senior / PI author. Renders a `‡` superscript + a "‡Principal
+     * investigator" caption. Suppressed on single-author papers. */
+    principalInvestigator?: boolean
     email?: string
     orcid?: string
   }