diff --git a/app/src/main/java/com/hsdiary/ui/daydetail/DayDetailScreen.kt b/app/src/main/java/com/hsdiary/ui/daydetail/DayDetailScreen.kt
index 33ff1a3..a300113 100644
--- a/app/src/main/java/com/hsdiary/ui/daydetail/DayDetailScreen.kt
+++ b/app/src/main/java/com/hsdiary/ui/daydetail/DayDetailScreen.kt
@@ -152,7 +152,7 @@ private fun CycleSection(
         }
 
         // Period day-of-period badge
-        if (state.periodActive && state.periodDayNumber > 0) {
+        if (state.hasActiveCycle && state.periodDayNumber > 0) {
             Text(
                 "Period day ${state.periodDayNumber}",
                 style = MaterialTheme.typography.bodySmall,
@@ -171,7 +171,7 @@ private fun CycleSection(
                 label = { Text("Period started") },
                 leadingIcon = {
                     Icon(
-                        if (state.isPeriodStart) Icons.Default.Check else Icons.Default.PlayArrow,
+                        if (state.isPeriodStart || state.hasActiveCycle) Icons.Default.Check else Icons.Default.PlayArrow,
                         contentDescription = null,
                         modifier = Modifier.size(16.dp)
                     )
@@ -180,7 +180,8 @@ private fun CycleSection(
             FilterChip(
                 selected = state.isPeriodEnd,
                 onClick = onTogglePeriodEnd,
-                enabled = state.isPeriodStart || state.periodActive || state.isPeriodEnd,
+                enabled = state.isPeriodEnd ||
+                    (state.hasActiveCycle && state.cycleStartDate != null && state.date > state.cycleStartDate),
                 label = { Text("Period ended") },
                 leadingIcon = {
                     Icon(
diff --git a/app/src/main/java/com/hsdiary/ui/daydetail/DayDetailViewModel.kt b/app/src/main/java/com/hsdiary/ui/daydetail/DayDetailViewModel.kt
index 48c7b26..aaae3c7 100644
--- a/app/src/main/java/com/hsdiary/ui/daydetail/DayDetailViewModel.kt
+++ b/app/src/main/java/com/hsdiary/ui/daydetail/DayDetailViewModel.kt
@@ -31,6 +31,8 @@ data class DayDetailUiState(
     val isPeriodStart: Boolean = false,
     val isPeriodEnd: Boolean = false,
     val periodDayNumber: Int = 0,       // day-of-period for this date (1 = first day)
+    val hasActiveCycle: Boolean = false, // a cycle record spans this date (start logged, regardless of which day)
+    val cycleStartDate: LocalDate? = null,
     val notes: String = "",
     val conditions: Map<String, Int> = emptyMap(),
     val definitions: List<ConditionDefinitionEntity> = emptyList(),
@@ -88,12 +90,11 @@ class DayDetailViewModel @Inject constructor(
         val isPeriodStart = isFemale && cycleRepository.isPeriodStart(activeProfile.id, dateStr)
         val isPeriodEnd = isFemale && cycleRepository.isPeriodEnd(activeProfile.id, dateStr)
 
-        // Calculate day-of-period: how many days from the period start to this date
-        val periodDayNumber = if (isFemale && dayLog.periodActive) {
-            val record = cycleRepository.getRecordContainingDate(activeProfile.id, dateStr)
-            if (record != null) {
-                (date.toEpochDay() - LocalDate.parse(record.cycleStart).toEpochDay()).toInt() + 1
-            } else 0
+        val cycleRecord = if (isFemale) cycleRepository.getRecordContainingDate(activeProfile.id, dateStr) else null
+        val hasActiveCycle = cycleRecord != null
+        val cycleStartDate = cycleRecord?.let { LocalDate.parse(it.cycleStart) }
+        val periodDayNumber = if (cycleRecord != null) {
+            (date.toEpochDay() - LocalDate.parse(cycleRecord.cycleStart).toEpochDay()).toInt() + 1
         } else 0
 
         _uiState.value = DayDetailUiState(
@@ -105,6 +106,8 @@ class DayDetailViewModel @Inject constructor(
             isPeriodStart = isPeriodStart,
             isPeriodEnd = isPeriodEnd,
             periodDayNumber = periodDayNumber,
+            hasActiveCycle = hasActiveCycle,
+            cycleStartDate = cycleStartDate,
             notes = dayLog.notes ?: "",
             conditions = conditions,
             definitions = defsToShow,
@@ -136,6 +139,8 @@ class DayDetailViewModel @Inject constructor(
                     periodActive = false,
                     dayLog = updatedLog,
                     periodDayNumber = 0,
+                    hasActiveCycle = false,
+                    cycleStartDate = null,
                     isDirty = true
                 )
             } else {
@@ -150,6 +155,8 @@ class DayDetailViewModel @Inject constructor(
                     periodActive = true,
                     dayLog = updatedLog,
                     periodDayNumber = 1,
+                    hasActiveCycle = true,
+                    cycleStartDate = date,
                     isDirty = true
                 )
             }