diff --git a/src/modules/activities/components/ActivityCard.vue b/src/modules/activities/components/ActivityCard.vue
index b93d20a..d16c376 100644
--- a/src/modules/activities/components/ActivityCard.vue
+++ b/src/modules/activities/components/ActivityCard.vue
@@ -4,9 +4,10 @@ import { useI18n } from 'vue-i18n'
 import { format } from 'date-fns'
 import { Card, CardContent } from '@/components/ui/card'
 import { Badge } from '@/components/ui/badge'
-import { MapPin, Calendar, Ticket, User } from 'lucide-vue-next'
+import { MapPin, Calendar, Ticket, User, CheckCircle2 } from 'lucide-vue-next'
 import BookmarkButton from './BookmarkButton.vue'
 import { useDateLocale } from '../composables/useDateLocale'
+import { useOwnedTickets } from '../composables/useOwnedTickets'
 import type { Activity } from '../types/activity'
 
 const props = defineProps<{
@@ -19,6 +20,9 @@ const emit = defineEmits<{
 
 const { t } = useI18n()
 const { dateLocale } = useDateLocale()
+const { paidCount } = useOwnedTickets()
+
+const ownedCount = computed(() => paidCount(props.activity.id))
 
 const dateDisplay = computed(() => {
   const a = props.activity
@@ -173,6 +177,20 @@ const placeholderBg = computed(() => {
             {{ t('activities.detail.soldOut') }}
           </span>
         </div>
+
+        <!-- Owned tickets — shown when the current user holds at
+             least one paid ticket for this activity. Sits next to
+             the availability line so the buyer can see at a glance
+             whether they've already bought in. -->
+        <div
+          v-if="ownedCount > 0"
+          class="flex items-center gap-1.5 text-sm text-primary"
+        >
+          <CheckCircle2 class="w-3.5 h-3.5 shrink-0" />
+          <span>
+            {{ t('activities.detail.ticketsOwned', { count: ownedCount }, ownedCount) }}
+          </span>
+        </div>
       </div>
     </CardContent>
   </Card>
diff --git a/src/modules/activities/composables/useOwnedTickets.ts b/src/modules/activities/composables/useOwnedTickets.ts
new file mode 100644
index 0000000..5ea5d44
--- /dev/null
+++ b/src/modules/activities/composables/useOwnedTickets.ts
@@ -0,0 +1,113 @@
+import { computed, ref, watch } from 'vue'
+import { useAuth } from '@/composables/useAuthService'
+import { injectService, SERVICE_TOKENS } from '@/core/di-container'
+import type { TicketApiService } from '../services/TicketApiService'
+import type { ActivityTicket } from '../types/ticket'
+
+/**
+ * Module-level singleton: owned-ticket lookup keyed by activity id
+ * (== LNbits event id == NIP-52 d-tag, all the same string by
+ * extension contract). Lives at module scope so every <ActivityCard>
+ * + the detail page + the feed filter share ONE underlying fetch
+ * instead of each instance hitting the API.
+ *
+ * Auto-loads on first use after auth is ready, and re-loads when
+ * the current user changes (login/logout). Consumers that mutate the
+ * user's ticket set (e.g. a successful purchase) call `refresh()`
+ * directly so every surface reading this composable updates
+ * atomically.
+ */
+
+const tickets = ref<ActivityTicket[]>([])
+const isLoading = ref(false)
+const error = ref<Error | null>(null)
+let hasAutoLoaded = false
+let lastLoadedUserId: string | null = null
+
+async function fetchTickets(): Promise<void> {
+  const { isAuthenticated, currentUser } = useAuth()
+  if (!isAuthenticated.value || !currentUser.value) {
+    tickets.value = []
+    lastLoadedUserId = null
+    return
+  }
+
+  const ticketApi = injectService(SERVICE_TOKENS.TICKET_API) as TicketApiService
+  const lnbitsAPI = injectService(SERVICE_TOKENS.LNBITS_API) as any
+  const accessToken = lnbitsAPI?.getAccessToken?.() || ''
+
+  isLoading.value = true
+  error.value = null
+  try {
+    tickets.value = await ticketApi.fetchUserTickets(currentUser.value.id, accessToken)
+    lastLoadedUserId = currentUser.value.id
+  } catch (e) {
+    error.value = e instanceof Error ? e : new Error(String(e))
+    tickets.value = []
+  } finally {
+    isLoading.value = false
+  }
+}
+
+const ticketsByActivity = computed<Map<string, ActivityTicket[]>>(() => {
+  const m = new Map<string, ActivityTicket[]>()
+  for (const ticket of tickets.value) {
+    const existing = m.get(ticket.activityId)
+    if (existing) {
+      existing.push(ticket)
+    } else {
+      m.set(ticket.activityId, [ticket])
+    }
+  }
+  return m
+})
+
+const ownedActivityIds = computed<Set<string>>(() => {
+  const s = new Set<string>()
+  for (const ticket of tickets.value) {
+    if (ticket.paid) s.add(ticket.activityId)
+  }
+  return s
+})
+
+function getTickets(activityId: string): ActivityTicket[] {
+  return ticketsByActivity.value.get(activityId) ?? []
+}
+
+function paidCount(activityId: string): number {
+  return getTickets(activityId).filter(t => t.paid).length
+}
+
+export function useOwnedTickets() {
+  const { isAuthenticated, currentUser } = useAuth()
+
+  // First call kicks off the initial load. Subsequent calls just
+  // attach to the shared state.
+  if (!hasAutoLoaded) {
+    hasAutoLoaded = true
+    fetchTickets()
+
+    // Re-fetch when the current user changes (login / logout /
+    // account switch). Compares against the last-fetched user id
+    // so we don't re-fetch when other auth fields update (e.g.
+    // metadata refresh) without the user id changing.
+    watch(
+      () => currentUser.value?.id ?? null,
+      (id) => {
+        if (id !== lastLoadedUserId) fetchTickets()
+      },
+    )
+  }
+
+  return {
+    tickets,
+    ticketsByActivity,
+    ownedActivityIds,
+    getTickets,
+    paidCount,
+    refresh: fetchTickets,
+    isLoading,
+    error,
+    isAuthenticated,
+  }
+}