Add student birthday tracking with celebration banners and admin notification; v1.1.31

- Admin can set birthday (month/day) per student in Study Users panel
- Summer birthdays (Jun–Aug) prompt admin to set an alternate school-year date
- 🎂 badge on student card header during birthday week
- Dismissible happy birthday banner shown to student on their study hub
- Admin receives email notification on the celebration day, once per year

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

server/reminder.js

@@ -1,7 +1,8 @@
 import { Resend } from 'resend'
 import { state } from './state.js'
-import { queuePodcastChecklistWrite, queueCalendarEventsWrite } from './data.js'
+import { queuePodcastChecklistWrite, queueCalendarEventsWrite, queueStudyUsersWrite } from './data.js'
 import { DEFAULT_RESEND_FROM, DEFAULT_RESEND_TO } from './config.js'
+import { celebrationDateForYear } from './helpers.js'
 
 function toDateKey(date) {
   return date.toISOString().slice(0, 10)
@@ -64,6 +65,63 @@ async function checkReminders() {
     }
     if (changed) queueCalendarEventsWrite()
   }
+
+  // Birthdays — fire on the student's celebration day, once per calendar year
+  const users = state.studyUsers ?? []
+  let birthdayUsersChanged = false
+  const todayYear = new Date().getUTCFullYear()
+  const birthdayKids = []
+
+  for (const user of users) {
+    if (!user.birthdayMonth || !user.birthdayDay) continue
+    const celebDate = celebrationDateForYear(user, todayYear)
+    if (!celebDate) continue
+    if (todayKey !== celebDate) continue
+    if (user.birthdayEmailSentYear === todayYear) continue
+    birthdayKids.push({ name: user.displayName || user.username, birthdayMonth: user.birthdayMonth, birthdayDay: user.birthdayDay, hasAlternate: Boolean(user.birthdayAlternateMonth) })
+    user.birthdayEmailSentYear = todayYear
+    birthdayUsersChanged = true
+  }
+
+  if (birthdayKids.length > 0) {
+    await sendBirthdayNotificationEmail(birthdayKids)
+    if (birthdayUsersChanged) queueStudyUsersWrite()
+  }
+}
+
+async function sendBirthdayNotificationEmail(kids) {
+  if (!process.env.RESEND_API_KEY) return
+  try {
+    const resend = new Resend(process.env.RESEND_API_KEY)
+    const from = process.env.RESEND_FROM ?? DEFAULT_RESEND_FROM
+    const to = process.env.RESEND_TO ?? DEFAULT_RESEND_TO
+    const MONTHS = ['January','February','March','April','May','June','July','August','September','October','November','December']
+
+    const lines = kids.map(k => {
+      const bdayStr = `${MONTHS[k.birthdayMonth - 1]} ${k.birthdayDay}`
+      const alt = k.hasAlternate ? ' (celebrating on alternate date)' : ''
+      return `<li style="margin-bottom:6px"><strong>${k.name}</strong> — birthday: ${bdayStr}${alt}</li>`
+    }).join('')
+
+    const subject = kids.length === 1
+      ? `🎂 Birthday today: ${kids[0].name}`
+      : `🎂 ${kids.length} student birthdays today`
+
+    const html = `
+      <div style="font-family:system-ui,sans-serif;max-width:540px;margin:0 auto;color:#222">
+        <h2 style="color:#c8860a;margin-bottom:4px">🎂 Student Birthday Celebration</h2>
+        <p>The following student${kids.length > 1 ? 's have' : ' has'} a birthday celebration today — consider sending a special message or acknowledging them in your study community!</p>
+        <ul style="padding-left:1.2em">${lines}</ul>
+        <hr style="border:none;border-top:1px solid #eee;margin:16px 0">
+        <p style="color:#777;font-size:0.85rem">To edit birthday info, open the Study Users panel in your admin settings.</p>
+      </div>
+    `
+    const { error } = await resend.emails.send({ from, to, subject, html })
+    if (error) console.error('[birthday] send error:', error)
+    else console.log(`[birthday] notification sent for ${kids.map(k => k.name).join(', ')}`)
+  } catch (err) {
+    console.error('[birthday] send exception:', err)
+  }
 }
 
 const TYPE_ICONS = { episode: '📅', general: '📌', recording: '🎙️', social: '📱', task: '✅' }