fix(activities): pause scanner after each decode, require tap to scan next

Without a pause gate the qr-scanner's 5-fps decode loop instantly
fires another scan on whatever QR is still in frame — most
visibly, the ticket that just registered immediately re-fires as
"already scanned this session". The operator at the door never
gets a beat to confirm the result or act on it (let the attendee
in, deny entry, redirect to manual lookup, etc.).

useTicketScanner gains an `isPaused` ref that flips to true the
moment a decode resolves (success, error, or duplicate-session
de-dup) and gates further `onDecode` calls. The camera keeps
streaming so resumption is instant — only the decode handler is
muted.

The page replaces the small "Dismiss" button with a full-width
"Scan next" CTA below the result banner. Same place every time so
the operator's hand can stay in muscle memory; disabled while the
in-flight RPC is still sending. Result banner upgrades to a
slightly larger icon + label so the success/failure is readable
at arm's length over the venue.

`clearScanned` also resets `isPaused` so the operator can recover
from a stuck state via the "Clear list" affordance.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/modules/activities/composables/useTicketScanner.ts

@@ -39,6 +39,17 @@ export function useTicketScanner(activityId: Ref<string>) {
 
   const isProcessing = ref(false)
   const lastScan = ref<ScanResult | null>(null)
+  /**
+   * Set to `true` immediately after a decode resolves (success or
+   * failure) and stays true until the operator dismisses or taps
+   * "Scan next". While paused, further `onDecode` calls are dropped
+   * — the camera keeps streaming for instant resume but the result
+   * banner sticks so the door can confirm the outcome before
+   * moving on. Without this, the 5-fps decode loop instantly
+   * fires "already scanned this session" on the very ticket that
+   * just succeeded.
+   */
+  const isPaused = ref(false)
   const scanned = useLocalStorage<ScanRecord[]>(
     () => `activities_scanned_${activityId.value}`,
     [],
@@ -51,7 +62,7 @@ export function useTicketScanner(activityId: Ref<string>) {
   }
 
   async function onDecode(qrText: string): Promise<void> {
-    if (isProcessing.value) return
+    if (isProcessing.value || isPaused.value) return
     const ticketId = parseTicketId(qrText).trim()
     if (!ticketId) return
 
@@ -60,6 +71,7 @@ export function useTicketScanner(activityId: Ref<string>) {
     // of the camera for multiple decode frames.
     if (scanned.value.some(r => r.ticketId === ticketId)) {
       lastScan.value = { status: 'duplicate-session', ticketId }
+      isPaused.value = true
       return
     }
 
@@ -90,24 +102,32 @@ export function useTicketScanner(activityId: Ref<string>) {
       }
     } finally {
       isProcessing.value = false
+      // Pause the decode loop regardless of outcome. The operator
+      // taps "Scan next" to resume; this guarantees they see the
+      // banner and can correct (let the attendee in, deny entry,
+      // etc.) before the next QR comes into frame.
+      isPaused.value = true
     }
   }
 
+  function resume() {
+    lastScan.value = null
+    isPaused.value = false
+  }
+
   function clearScanned() {
     scanned.value = []
     lastScan.value = null
-  }
+    isPaused.value = false
-
-  function dismissLastScan() {
-    lastScan.value = null
   }
 
   return {
     isProcessing,
+    isPaused,
     lastScan,
     scanned,
     onDecode,
+    resume,
     clearScanned,
-    dismissLastScan,
   }
 }

src/modules/activities/views/ScanTicketsPage.vue

@@ -1,7 +1,7 @@
 <script setup lang="ts">
 import { computed, ref } from 'vue'
 import { useRoute, useRouter } from 'vue-router'
-import { ArrowLeft, CheckCircle2, AlertCircle, Clock, Ticket, Trash2 } from 'lucide-vue-next'
+import { ArrowLeft, CheckCircle2, AlertCircle, Clock, Ticket, Trash2, ScanLine } from 'lucide-vue-next'
 import { format } from 'date-fns'
 import { Button } from '@/components/ui/button'
 import { Badge } from '@/components/ui/badge'
@@ -19,11 +19,12 @@ const { activity } = useActivityDetail(activityId.value)
 
 const {
   isProcessing,
+  isPaused,
   lastScan,
   scanned,
   onDecode,
+  resume,
   clearScanned,
-  dismissLastScan,
 } = useTicketScanner(activityId)
 
 const scannerOpen = ref(true)
@@ -92,8 +93,10 @@ function fmtTime(iso: string) {
       </Button>
     </div>
 
-    <!-- Last-scan banner — single line, dismissable. Keeps the
+    <!-- Last-scan result. Sticks until the operator taps "Scan
-         scanner viewport clean while still surfacing the result. -->
+         next" — gives them time to verify the outcome and act on
+         it (let the attendee in, deny entry, etc.) before the
+         decode loop picks up the next QR. -->
     <div
       v-if="lastScan"
       class="mt-4 p-4 rounded-lg border flex items-start gap-3"
@@ -105,18 +108,18 @@ function fmtTime(iso: string) {
     >
       <CheckCircle2
         v-if="lastScanVariant === 'success'"
-        class="w-5 h-5 text-emerald-500 shrink-0 mt-0.5"
+        class="w-6 h-6 text-emerald-500 shrink-0 mt-0.5"
       />
       <Clock
         v-else-if="lastScanVariant === 'warning'"
-        class="w-5 h-5 text-amber-500 shrink-0 mt-0.5"
+        class="w-6 h-6 text-amber-500 shrink-0 mt-0.5"
       />
       <AlertCircle
         v-else
-        class="w-5 h-5 text-destructive shrink-0 mt-0.5"
+        class="w-6 h-6 text-destructive shrink-0 mt-0.5"
       />
       <div class="flex-1 min-w-0">
-        <p class="text-sm font-medium text-foreground">
+        <p class="text-base font-semibold text-foreground">
           <template v-if="lastScan.status === 'ok'">
             Registered
             <span v-if="lastScan.ticket?.name" class="font-normal text-muted-foreground">
@@ -130,18 +133,29 @@ function fmtTime(iso: string) {
             {{ lastScan.message || 'Scan failed' }}
           </template>
         </p>
-        <p class="text-xs font-mono text-muted-foreground break-all mt-0.5">
+        <p class="text-xs font-mono text-muted-foreground break-all mt-1">
           {{ lastScan.ticketId }}
         </p>
       </div>
-      <Button variant="ghost" size="sm" class="shrink-0" @click="dismissLastScan">
-        Dismiss
-      </Button>
     </div>
 
-    <!-- Processing hint -->
+    <!-- "Scan next" CTA — primary action when a result is pending,
+         so the operator's hand goes to the same place every time
+         (full-width button below the result). Disabled while the
+         RPC is still in-flight. -->
+    <Button
+      v-if="isPaused"
+      class="w-full mt-3 gap-1.5"
+      size="lg"
+      :disabled="isProcessing"
+      @click="resume"
+    >
+      <ScanLine class="w-4 h-4" />
+      <span v-if="isProcessing">Sending…</span>
+      <span v-else>Scan next</span>
+    </Button>
     <p
-      v-if="isProcessing"
+      v-else-if="isProcessing"
       class="text-xs text-center text-muted-foreground mt-3"
     >
       Sending registration over Nostr…