diff --git a/frontend/src/pages/chat/composables/useSidebarPlan.ts b/frontend/src/pages/chat/composables/useSidebarPlan.ts
index e4e17d8..2499587 100644
--- a/frontend/src/pages/chat/composables/useSidebarPlan.ts
+++ b/frontend/src/pages/chat/composables/useSidebarPlan.ts
@@ -19,15 +19,15 @@ export const sidebarCollapsedModules = [
 ]
 
 function formatDateKey(date: Date) {
-  const year = date.getFullYear()
-  const month = String(date.getMonth() + 1).padStart(2, '0')
-  const day = String(date.getDate()).padStart(2, '0')
+  const year = date.getUTCFullYear()
+  const month = String(date.getUTCMonth() + 1).padStart(2, '0')
+  const day = String(date.getUTCDate()).padStart(2, '0')
   return `${year}-${month}-${day}`
 }
 
 function formatMonthKey(date: Date) {
-  const year = date.getFullYear()
-  const month = String(date.getMonth() + 1).padStart(2, '0')
+  const year = date.getUTCFullYear()
+  const month = String(date.getUTCMonth() + 1).padStart(2, '0')
   return `${year}-${month}`
 }
 
@@ -39,8 +39,10 @@ export function useSidebarPlan(clientTimeRef: { value: Date }, loadDailyDigestFn
   // Build a map of date -> has conversation
   const conversationDateMap = computed(() => {
     const map = new Map<string, boolean>()
-    conversationsRef.forEach((conv) => {
-      const dateKey = formatDateKey(new Date(conv.updated_at))
+    const conversations = Array.isArray(conversationsRef) ? conversationsRef : (conversationsRef.value ?? [])
+    conversations.forEach((conv) => {
+      const date = new Date(conv.updated_at)
+      const dateKey = formatDateKey(date)
       map.set(dateKey, true)
     })
     return map
@@ -50,21 +52,22 @@ export function useSidebarPlan(clientTimeRef: { value: Date }, loadDailyDigestFn
   const monthPlanSummaryMap = computed(() => new Map(monthPlanDays.value.map((item) => [item.date, item])))
 
   const calendarCells = computed(() => {
-    const year = clientTimeRef.value.getFullYear()
-    const month = clientTimeRef.value.getMonth()
-    const daysInMonth = new Date(year, month + 1, 0).getDate()
-    const firstDayOffset = (new Date(year, month, 1).getDay() + 6) % 7
+    const year = clientTimeRef.value.getUTCFullYear()
+    const month = clientTimeRef.value.getUTCMonth()
+    const daysInMonth = new Date(Date.UTC(year, month + 1, 0)).getUTCDate()
+    const firstDayOffset = (new Date(Date.UTC(year, month, 1)).getUTCDay() + 6) % 7
+    const today = clientTimeRef.value.getUTCDate()
     const cells: Array<{ key: string; value: number | null; active: boolean; busy: boolean; selected: boolean; hasConversation: boolean }> = []
     for (let index = 0; index < firstDayOffset; index += 1) {
       cells.push({ key: `blank-start-${index}`, value: null, active: false, busy: false, selected: false, hasConversation: false })
     }
     for (let day = 1; day <= daysInMonth; day += 1) {
-      const monthDate = new Date(year, month, day)
+      const monthDate = new Date(Date.UTC(year, month, day))
       const dateKey = formatDateKey(monthDate)
       const summary = monthPlanSummaryMap.value.get(dateKey)
       const busy = Boolean(summary && (summary.todo_total + summary.task_due_total + summary.goal_total + summary.reminder_total) > 0)
       const hasConv = conversationDateMap.value.get(dateKey) || false
-      cells.push({ key: dateKey, value: day, active: day === clientTimeRef.value.getDate(), busy, selected: dateKey === selectedDate.value, hasConversation: hasConv })
+      cells.push({ key: dateKey, value: day, active: day === today, busy, selected: dateKey === selectedDate.value, hasConversation: hasConv })
     }
     while (cells.length % 7 !== 0) {
       cells.push({ key: `blank-end-${cells.length}`, value: null, active: false, busy: false, selected: false, hasConversation: false })
@@ -72,8 +75,8 @@ export function useSidebarPlan(clientTimeRef: { value: Date }, loadDailyDigestFn
     return cells
   })
 
-  const calendarYear = computed(() => clientTimeRef.value.getFullYear())
-  const calendarMonth = computed(() => clientTimeRef.value.getMonth() + 1)
+  const calendarYear = computed(() => clientTimeRef.value.getUTCFullYear())
+  const calendarMonth = computed(() => clientTimeRef.value.getUTCMonth() + 1)
 
   const todayPlanCounters = computed(() => {
     const detail = todayPlanDetail.value
diff --git a/frontend/src/pages/chat/index.vue b/frontend/src/pages/chat/index.vue
index 3cc2d9b..95f2b89 100644
--- a/frontend/src/pages/chat/index.vue
+++ b/frontend/src/pages/chat/index.vue
@@ -121,12 +121,14 @@ function handleCalendarDateSelect(dateKey: string) {
   // Reload conversations to get latest data
   loadConversations().then(() => {
     // Find conversation that matches the selected date (by updated_at)
-    const targetDate = new Date(dateKey)
-    const targetDateStart = new Date(targetDate.getFullYear(), targetDate.getMonth(), targetDate.getDate())
-    const targetDateEnd = new Date(targetDate.getFullYear(), targetDate.getMonth(), targetDate.getDate() + 1)
+    // Use UTC to avoid timezone issues
+    const [year, month, day] = dateKey.split('-').map(Number)
+    const targetDateStart = new Date(Date.UTC(year, month - 1, day))
+    const targetDateEnd = new Date(Date.UTC(year, month - 1, day + 1))
 
     // Find conversation that falls on the selected date
-    const conversation = store.conversations.find((conv) => {
+    const conversations = store.conversations.value ?? store.conversations
+    const conversation = conversations.find((conv) => {
       const convDate = new Date(conv.updated_at)
       return convDate >= targetDateStart && convDate < targetDateEnd
     })
@@ -300,8 +302,8 @@ function renderMarkdown(content: string) {
                 v-for="cell in calendarCells"
                 :key="cell.key"
                 class="calendar-day"
-                :class="{ active: cell.active, busy: cell.busy, muted: cell.value === null, selected: cell.selected, clickable: cell.hasConversation || cell.active }"
-                @click="(cell.hasConversation || cell.active) && handleCalendarDateSelect(cell.key)"
+                :class="{ active: cell.active, busy: cell.busy, muted: cell.value === null, selected: cell.selected, clickable: cell.active || cell.hasConversation }"
+                @click="(cell.active || cell.hasConversation) && handleCalendarDateSelect(cell.key)"
               >
                 {{ cell.value ?? '' }}
                 <span v-if="cell.hasConversation" class="conv-indicator"></span>