feat: silent background polling for dashboard and briefing views

HomeView: setInterval every 90s refreshes events, orphan tasks/notes,
and hero next-up task. Never touches loading ref, so the page content
stays stable — only the data silently swaps when the fetch completes.
Skips when document.hidden or initial load is still in progress.

BriefingView: setInterval every 60s refetches today's messages, but
only when viewing today's conversation and not currently streaming.
Compares message count and last message content before updating to
avoid unnecessary re-renders.

Both timers are cleared on unmount.

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

frontend/src/views/BriefingView.vue

@@ -189,9 +189,31 @@ function toMsg(m: BriefingMessage): Message {
   }
 }
 
+// ─── Background refresh (no-flicker) ─────────────────────────────────────────
+let _refreshTimer: ReturnType<typeof setInterval> | null = null
+
+async function _backgroundRefreshMessages() {
+  if (document.hidden || chatStore.streaming || !isToday.value || !todayConvId.value) return
+  try {
+    const today = await getBriefingToday()
+    if (!today) return
+    const fresh = today.messages
+    const last = fresh[fresh.length - 1]
+    const cur = messages.value[messages.value.length - 1]
+    if (fresh.length !== messages.value.length || last?.content !== cur?.content) {
+      messages.value = fresh
+    }
+  } catch { /* silent — don't disturb the UI on network hiccup */ }
+}
+
 onMounted(async () => {
   await checkSetup()
   if (!showWizard.value) await loadAll()
+  _refreshTimer = setInterval(_backgroundRefreshMessages, 60_000)
+})
+
+onUnmounted(() => {
+  if (_refreshTimer !== null) clearInterval(_refreshTimer)
 })
 </script>
 

frontend/src/views/HomeView.vue

@@ -82,6 +82,43 @@ function milestoneColor(index: number): string {
   return palette[index % palette.length];
 }
 
+// ─── Background refresh (no-flicker) ─────────────────────────────────────────
+// Runs on a timer while the page is visible. Never touches `loading` so
+// existing content stays on screen while the fetch is in flight.
+
+let _refreshTimer: ReturnType<typeof setInterval> | null = null
+
+function _dateRange() {
+  const today = new Date()
+  const nextWeek = new Date(today)
+  nextWeek.setDate(today.getDate() + 7)
+  return {
+    todayStr: today.toISOString().slice(0, 10) + 'T00:00:00',
+    nextWeekStr: nextWeek.toISOString().slice(0, 10) + 'T23:59:59',
+  }
+}
+
+function _backgroundRefresh() {
+  if (document.hidden || loading.value) return
+  const { todayStr, nextWeekStr } = _dateRange()
+  Promise.allSettled([
+    listEvents(todayStr, nextWeekStr),
+    apiGet<TaskListResponse>('/api/tasks?no_project=true&sort=updated_at&order=desc&limit=8'),
+    apiGet<{ notes: Note[] }>('/api/notes?type=note&no_project=true&sort=updated_at&order=desc&limit=6'),
+  ]).then(([eventsRes, tasksRes, notesRes]) => {
+    if (eventsRes.status === 'fulfilled') upcomingEvents.value = eventsRes.value
+    if (tasksRes.status === 'fulfilled') orphanTasks.value = tasksRes.value.tasks
+    if (notesRes.status === 'fulfilled') orphanNotes.value = notesRes.value.notes
+  })
+  if (heroProject.value) {
+    apiGet<TaskListResponse>(
+      `/api/tasks?project_id=${heroProject.value.id}&status=todo&sort=updated_at&order=desc&limit=1`
+    )
+      .then((r) => { heroNextUp.value = r.tasks[0] ?? null })
+      .catch(() => {})
+  }
+}
+
 // ─── Data loading ─────────────────────────────────────────────────────────────
 
 onMounted(async () => {
@@ -135,6 +172,8 @@ onMounted(async () => {
   // Focus chat input after data loads
   chatInputRef.value?.focus();
   loadProjects();
+
+  _refreshTimer = setInterval(_backgroundRefresh, 90_000)
 });
 
 async function loadProjects() {
@@ -200,6 +239,7 @@ onMounted(() => {
 });
 onUnmounted(() => {
   document.removeEventListener("shortcut:focus-chat", onFocusChatShortcut);
+  if (_refreshTimer !== null) clearInterval(_refreshTimer)
 });
 
 const chatStore = useChatStore();