diff --git a/src/components/CalendarView.vue b/src/components/CalendarView.vue
index 1f84273..1efb5a4 100644
--- a/src/components/CalendarView.vue
+++ b/src/components/CalendarView.vue
@@ -51,6 +51,19 @@ const selection = ref({ startDate: null, dayCount: 0 })
 const isDragging = ref(false)
 const dragAnchor = ref(null)
 
+// Rebuild visible weeks whenever selection changes so day.isSelected stays in sync.
+watch(
+  () => [selection.value.startDate, selection.value.dayCount],
+  () => {
+    // Skip if no selection (both null/0) to avoid unnecessary work.
+    if (!selection.value.startDate || selection.value.dayCount === 0) {
+      scheduleRebuild('selection-clear')
+    } else {
+      scheduleRebuild('selection')
+    }
+  },
+)
+
 const DOUBLE_TAP_DELAY = 300
 const pendingTap = ref({ date: null, time: 0, type: null })
 const suppressMouseUntil = ref(0)