Merge remote-tracking branch 'origin/main' into worktree-feat+translations

app/src/main/AndroidManifest.xml

@@ -5,6 +5,13 @@
     <uses-permission android:name="android.permission.READ_CALENDAR" />
     <uses-permission android:name="android.permission.WRITE_CALENDAR" />
     <uses-permission android:name="android.permission.POST_NOTIFICATIONS" />
+    <!--
+      Lets the "Reliable delivery" setting open the direct system dialog to
+      exempt Calendula from battery optimisation (so reminder broadcasts aren't
+      delayed by Doze). Used only to launch that dialog; falls back to the
+      battery-optimisation list if the OS declines the direct intent.
+    -->
+    <uses-permission android:name="android.permission.REQUEST_IGNORE_BATTERY_OPTIMIZATIONS" />
 
     <!-- Package visibility (Android 11+): without this, getLaunchIntentForPackage
          returns null and the calendar manager's per-account "manage" button can't

app/src/main/java/de/jeanlucmakiola/calendula/data/calendar/AllDayReminderEncoding.kt

@@ -0,0 +1,70 @@
+package de.jeanlucmakiola.calendula.data.calendar
+
+import java.time.Instant
+import java.time.LocalDate
+import java.time.LocalTime
+import java.time.ZoneId
+import java.time.ZoneOffset
+import java.time.temporal.ChronoUnit
+
+/**
+ * Translates an all-day reminder between the **semantic** lead time the UI
+ * speaks (whole days before the event — "1 day before") and the **raw**
+ * `CalendarContract.Reminders.MINUTES` offset the provider stores.
+ *
+ * Calendula schedules no alarms itself: the provider fires a reminder at
+ * `DTSTART − MINUTES` (the Etar model). An all-day event's DTSTART is **UTC
+ * midnight** (see [EventWriteTimes]), so a raw `MINUTES = 1440` ("1 day") lands
+ * on UTC-midnight of the previous day — 02:00 local in CEST, not the morning.
+ *
+ * To fire at a chosen wall-clock time we encode that time *into* the offset:
+ * `MINUTES = UTC-midnight(startDate) − (localInstant of [timeOfDayMinutes] on the
+ * day [semanticMinutes] before)`. The single fixed offset can only be tuned for
+ * the event's own date, so a recurring all-day series or a post-creation
+ * timezone change drifts the fire time by the offset delta (±1h across DST) —
+ * an inherent limit of the provider model, shared by Etar.
+ */
+private const val MINUTES_PER_DAY = 1_440
+private const val MILLIS_PER_MINUTE = 60_000L
+
+/**
+ * Raw provider `MINUTES` for an all-day reminder set [semanticMinutes] before the
+ * event (a whole-day multiple; sub-day remainders are dropped), so it fires at
+ * [timeOfDayMinutes] (minutes from local midnight) in [zone]. The result may be
+ * **negative** — e.g. "at time of event" at 09:00 CEST encodes to −420, meaning
+ * the provider fires *after* DTSTART; this is valid and must not be clamped.
+ * A negative [semanticMinutes] is the "provider default" sentinel and passes
+ * through unchanged.
+ */
+internal fun toProviderAllDayMinutes(
+    semanticMinutes: Int,
+    startDate: LocalDate,
+    zone: ZoneId,
+    timeOfDayMinutes: Int,
+): Int {
+    if (semanticMinutes < 0) return semanticMinutes
+    val utcMidnight = startDate.atStartOfDay(ZoneOffset.UTC).toInstant().toEpochMilli()
+    val fire = startDate.minusDays((semanticMinutes / MINUTES_PER_DAY).toLong())
+        .atTime(LocalTime.of(timeOfDayMinutes / 60, timeOfDayMinutes % 60))
+        .atZone(zone).toInstant().toEpochMilli()
+    return ((utcMidnight - fire) / MILLIS_PER_MINUTE).toInt()
+}
+
+/**
+ * Recover the semantic whole-day lead time from a raw all-day reminder
+ * [rawMinutes]. Keys off the **local date** of the encoded fire instant, so it
+ * returns the right day count regardless of which [timeOfDayMinutes] wrote the
+ * row — including pre-feature rows (raw multiples of 1440, fired at UTC midnight)
+ * and rows written under a different timezone. A negative [rawMinutes] (fire
+ * after DTSTART) folds to day 0.
+ */
+internal fun fromProviderAllDayMinutes(
+    rawMinutes: Int,
+    startDate: LocalDate,
+    zone: ZoneId,
+): Int {
+    val utcMidnight = startDate.atStartOfDay(ZoneOffset.UTC).toInstant().toEpochMilli()
+    val fireLocalDate = Instant.ofEpochMilli(utcMidnight - rawMinutes * MILLIS_PER_MINUTE)
+        .atZone(zone).toLocalDate()
+    return ChronoUnit.DAYS.between(fireLocalDate, startDate).toInt() * MINUTES_PER_DAY
+}

app/src/main/java/de/jeanlucmakiola/calendula/data/calendar/CalendarDataSource.kt

@@ -20,6 +20,7 @@ import de.jeanlucmakiola.calendula.domain.EventForm
 import de.jeanlucmakiola.calendula.domain.EventInstance
 import de.jeanlucmakiola.calendula.domain.Reminder
 import de.jeanlucmakiola.calendula.domain.rruleTruncatedAt
+import kotlinx.datetime.toJavaLocalDate
 import java.time.ZoneId
 import java.time.ZoneOffset
 import javax.inject.Inject
@@ -60,24 +61,40 @@ interface CalendarDataSource {
     /** Permanently delete a local calendar the app owns, with all its events. */
     fun deleteCalendar(id: Long)
 
-    /** Insert a new event; returns the new `Events._ID`. */
-    fun insertEvent(form: EventForm): Long
+    /**
+     * Insert a new event; returns the new `Events._ID`. [allDayReminderTimeMinutes]
+     * (minutes from local midnight) is the wall-clock time all-day reminders
+     * should fire at — encoded into each all-day reminder's provider offset
+     * (ignored for timed events).
+     */
+    fun insertEvent(form: EventForm, allDayReminderTimeMinutes: Int): Long
 
     /**
      * Update an existing event (for recurring events: the whole series) to
      * match [updated]. [original] is the form as it was prefilled from the
      * event, so only fields the user actually changed are written and the
      * reminder rows can be diffed instead of wiped.
+     * [allDayReminderTimeMinutes]: see [insertEvent].
      */
-    fun updateEvent(eventId: Long, original: EventForm, updated: EventForm)
+    fun updateEvent(
+        eventId: Long,
+        original: EventForm,
+        updated: EventForm,
+        allDayReminderTimeMinutes: Int,
+    )
 
     /**
      * Change a single occurrence of a recurring event by inserting a
      * modified-occurrence exception at [beginMillis] (the occurrence's
      * `Instances.BEGIN`) carrying [form]'s values; returns the exception
-     * row's `Events._ID`.
+     * row's `Events._ID`. [allDayReminderTimeMinutes]: see [insertEvent].
      */
-    fun updateOccurrence(eventId: Long, beginMillis: Long, form: EventForm): Long
+    fun updateOccurrence(
+        eventId: Long,
+        beginMillis: Long,
+        form: EventForm,
+        allDayReminderTimeMinutes: Int,
+    ): Long
 
     /**
      * Change a recurring event from the occurrence at [beginMillis] onwards
@@ -92,6 +109,7 @@ interface CalendarDataSource {
         beginMillis: Long,
         original: EventForm,
         updated: EventForm,
+        allDayReminderTimeMinutes: Int,
     ): Long
 
     /**
@@ -265,7 +283,33 @@ class AndroidCalendarDataSource @Inject constructor(
 
     private data class CalendarAccount(val name: String, val type: String)
 
-    override fun insertEvent(form: EventForm): Long {
+    /**
+     * The raw provider `MINUTES` to store for one of [form]'s reminders: an
+     * all-day reminder is shifted to fire at [allDayReminderTimeMinutes] local
+     * (see [toProviderAllDayMinutes]); a timed reminder is its lead time as-is.
+     */
+    private fun providerReminderMinutes(
+        form: EventForm,
+        minutes: Int,
+        allDayReminderTimeMinutes: Int,
+    ): Int = if (form.isAllDay) {
+        toProviderAllDayMinutes(
+            semanticMinutes = minutes,
+            startDate = form.start.date.toJavaLocalDate(),
+            zone = ZoneId.systemDefault(),
+            timeOfDayMinutes = allDayReminderTimeMinutes,
+        )
+    } else {
+        minutes
+    }
+
+    /** [form]'s reminders as the distinct raw provider offsets to store. */
+    private fun encodedReminders(form: EventForm, allDayReminderTimeMinutes: Int): List<Int> =
+        form.reminders
+            .map { providerReminderMinutes(form, it, allDayReminderTimeMinutes) }
+            .distinct()
+
+    override fun insertEvent(form: EventForm, allDayReminderTimeMinutes: Int): Long {
         val times = form.toWriteTimes(ZoneId.systemDefault())
         val values = ContentValues().apply {
             put(
@@ -303,20 +347,26 @@ class AndroidCalendarDataSource @Inject constructor(
         val eventId = ContentUris.parseId(uri)
         // Best effort (spec §8): the event exists at this point — a reminder
         // that fails to attach is logged, not surfaced as a failed create.
-        form.reminders.distinct().forEach { minutes ->
-            val reminder = ContentValues().apply {
-                put(CalendarContract.Reminders.EVENT_ID, eventId)
-                put(CalendarContract.Reminders.MINUTES, minutes)
-                put(CalendarContract.Reminders.METHOD, CalendarContract.Reminders.METHOD_ALERT)
+        encodedReminders(form, allDayReminderTimeMinutes)
+            .forEach { minutes ->
+                val reminder = ContentValues().apply {
+                    put(CalendarContract.Reminders.EVENT_ID, eventId)
+                    put(CalendarContract.Reminders.MINUTES, minutes)
+                    put(CalendarContract.Reminders.METHOD, CalendarContract.Reminders.METHOD_ALERT)
+                }
+                if (resolver.insert(CalendarContract.Reminders.CONTENT_URI, reminder) == null) {
+                    Log.w(TAG, "Failed to attach reminder ($minutes min) to event $eventId")
+                }
             }
-            if (resolver.insert(CalendarContract.Reminders.CONTENT_URI, reminder) == null) {
-                Log.w(TAG, "Failed to attach reminder ($minutes min) to event $eventId")
-            }
-        }
         return eventId
     }
 
-    override fun updateEvent(eventId: Long, original: EventForm, updated: EventForm) {
+    override fun updateEvent(
+        eventId: Long,
+        original: EventForm,
+        updated: EventForm,
+        allDayReminderTimeMinutes: Int,
+    ) {
         val values = buildEventUpdateValues(
             original = original,
             updated = updated,
@@ -332,13 +382,19 @@ class AndroidCalendarDataSource @Inject constructor(
             if (rows == 0) throw WriteFailedException("update event id=$eventId")
         }
         // Untouched reminder sets are left alone so unrelated edits can't
-        // disturb provider rows the form never knew about.
+        // disturb provider rows the form never knew about. The diff is on the
+        // form's semantic minutes; reconcile works in encoded provider minutes.
         if (updated.reminders.toSet() != original.reminders.toSet()) {
-            reconcileReminders(eventId, updated.reminders)
+            reconcileReminders(eventId, encodedReminders(updated, allDayReminderTimeMinutes))
         }
     }
 
-    override fun updateOccurrence(eventId: Long, beginMillis: Long, form: EventForm): Long {
+    override fun updateOccurrence(
+        eventId: Long,
+        beginMillis: Long,
+        form: EventForm,
+        allDayReminderTimeMinutes: Int,
+    ): Long {
         // The provider clones the series row and applies these values on top.
         val values = buildOccurrenceExceptionValues(
             form = form,
@@ -352,7 +408,7 @@ class AndroidCalendarDataSource @Inject constructor(
         val exceptionId = ContentUris.parseId(uri)
         // Whether the provider copied the parent's reminder rows is its
         // business — reconciling against the actual rows handles both ways.
-        reconcileReminders(exceptionId, form.reminders)
+        reconcileReminders(exceptionId, encodedReminders(form, allDayReminderTimeMinutes))
         return exceptionId
     }
 
@@ -361,16 +417,17 @@ class AndroidCalendarDataSource @Inject constructor(
         beginMillis: Long,
         original: EventForm,
         updated: EventForm,
+        allDayReminderTimeMinutes: Int,
     ): Long {
         val row = querySeriesRow(eventId)
         // From the first occurrence on (or with no rule to split) this is
         // just a series update.
         if (row.rrule.isNullOrBlank() || beginMillis <= row.dtStartMillis) {
-            updateEvent(eventId, original, updated)
+            updateEvent(eventId, original, updated, allDayReminderTimeMinutes)
             return eventId
         }
         // Insert the new series first: if it fails, the original is untouched.
-        val newEventId = insertEvent(updated)
+        val newEventId = insertEvent(updated, allDayReminderTimeMinutes)
         truncateSeries(eventId, row, beginMillis)
         return newEventId
     }
@@ -456,9 +513,11 @@ class AndroidCalendarDataSource @Inject constructor(
     }
 
     /**
-     * Make the event's reminder rows match [targetMinutes]: rows with other
-     * lead times are deleted, missing ones inserted as best-effort ALERTs
-     * (like insertEvent). Rows whose minutes survive keep their method.
+     * Make the event's reminder rows match [targetMinutes] — the raw provider
+     * offsets to store (already encoded via [encodedReminders], so all-day shifts
+     * are baked in and the diff matches the stored rows). Rows with other offsets
+     * are deleted, missing ones inserted as best-effort ALERTs (like insertEvent).
+     * Rows whose minutes survive keep their method.
      */
     private fun reconcileReminders(eventId: Long, targetMinutes: List<Int>) {
         val target = targetMinutes.toSet()

app/src/main/java/de/jeanlucmakiola/calendula/data/calendar/CalendarRepositoryImpl.kt

@@ -2,6 +2,7 @@ package de.jeanlucmakiola.calendula.data.calendar
 
 import de.jeanlucmakiola.calendula.data.di.IoDispatcher
 import de.jeanlucmakiola.calendula.data.prefs.CalendarPrefs
+import de.jeanlucmakiola.calendula.data.prefs.SettingsPrefs
 import de.jeanlucmakiola.calendula.domain.CalendarSource
 import de.jeanlucmakiola.calendula.domain.EventColorOption
 import de.jeanlucmakiola.calendula.domain.EventDetail
@@ -11,6 +12,7 @@ import kotlinx.coroutines.CoroutineDispatcher
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.MutableSharedFlow
 import kotlinx.coroutines.flow.combine
+import kotlinx.coroutines.flow.first
 import kotlinx.coroutines.flow.flow
 import kotlinx.coroutines.flow.flowOn
 import kotlinx.coroutines.flow.onStart
@@ -28,9 +30,14 @@ import javax.inject.Singleton
 class CalendarRepositoryImpl @Inject constructor(
     private val dataSource: CalendarDataSource,
     private val prefs: CalendarPrefs,
+    private val settingsPrefs: SettingsPrefs,
     @IoDispatcher private val io: CoroutineDispatcher,
 ) : CalendarRepository {
 
+    /** The configured wall-clock fire time for all-day reminders, read per write. */
+    private suspend fun allDayReminderTimeMinutes(): Int =
+        settingsPrefs.allDayReminderTimeMinutes.first()
+
     private val ticks = MutableSharedFlow<Unit>(
         replay = 0,
         extraBufferCapacity = 1,
@@ -93,7 +100,7 @@ class CalendarRepositoryImpl @Inject constructor(
         withContext(io) { dataSource.deleteCalendar(id) }
 
     override suspend fun createEvent(form: EventForm): Long = withContext(io) {
-        dataSource.insertEvent(form)
+        dataSource.insertEvent(form, allDayReminderTimeMinutes())
     }
 
     override suspend fun updateEvent(
@@ -101,7 +108,7 @@ class CalendarRepositoryImpl @Inject constructor(
         original: EventForm,
         updated: EventForm,
     ) = withContext(io) {
-        dataSource.updateEvent(eventId, original, updated)
+        dataSource.updateEvent(eventId, original, updated, allDayReminderTimeMinutes())
     }
 
     override suspend fun deleteEvent(eventId: Long) = withContext(io) {
@@ -113,7 +120,7 @@ class CalendarRepositoryImpl @Inject constructor(
         beginMillis: Long,
         form: EventForm,
     ): Long = withContext(io) {
-        dataSource.updateOccurrence(eventId, beginMillis, form)
+        dataSource.updateOccurrence(eventId, beginMillis, form, allDayReminderTimeMinutes())
     }
 
     override suspend fun updateEventFromOccurrence(
@@ -122,7 +129,9 @@ class CalendarRepositoryImpl @Inject constructor(
         original: EventForm,
         updated: EventForm,
     ): Long = withContext(io) {
-        dataSource.updateEventFromOccurrence(eventId, beginMillis, original, updated)
+        dataSource.updateEventFromOccurrence(
+            eventId, beginMillis, original, updated, allDayReminderTimeMinutes(),
+        )
     }
 
     override suspend fun deleteOccurrence(eventId: Long, beginMillis: Long) = withContext(io) {

app/src/main/java/de/jeanlucmakiola/calendula/data/calendar/EventDetailMapper.kt

@@ -13,6 +13,9 @@ import de.jeanlucmakiola.calendula.domain.EventInstance
 import de.jeanlucmakiola.calendula.domain.EventStatus
 import de.jeanlucmakiola.calendula.domain.Reminder
 import de.jeanlucmakiola.calendula.domain.ReminderMethod
+import java.time.Instant
+import java.time.ZoneId
+import java.time.ZoneOffset
 
 private const val TAG = "EventDetailMapper"
 
@@ -58,6 +61,7 @@ internal fun ColumnReader.toEventDetailCore(
     val color = eventColor ?: getInt(EventDetailProjection.IDX_CALENDAR_COLOR)
 
     val eventId = getLong(EventDetailProjection.IDX_EVENT_ID)
+    val isAllDay = getInt(EventDetailProjection.IDX_ALL_DAY) != 0
     val instance = EventInstance(
         instanceId = eventId,
         eventId = eventId,
@@ -65,11 +69,23 @@ internal fun ColumnReader.toEventDetailCore(
         title = title,
         start = begin.toKotlinInstantFromEpochMillis(),
         end = end.toKotlinInstantFromEpochMillis(),
-        isAllDay = getInt(EventDetailProjection.IDX_ALL_DAY) != 0,
+        isAllDay = isAllDay,
         color = color,
         location = getString(EventDetailProjection.IDX_LOCATION),
     )
 
+    // All-day reminders are stored as a wall-clock-shifted offset (see
+    // AllDayReminderEncoding); decode back to the whole-day lead time the form
+    // and detail screen speak. DTSTART is UTC midnight for all-day events, so the
+    // event's date is its UTC date.
+    val displayReminders = if (isAllDay) {
+        val startDate = Instant.ofEpochMilli(begin).atZone(ZoneOffset.UTC).toLocalDate()
+        val zone = ZoneId.systemDefault()
+        reminders.map { it.copy(minutes = fromProviderAllDayMinutes(it.minutes, startDate, zone)) }
+    } else {
+        reminders
+    }
+
     // STATUS shares its 0 value with STATUS_TENTATIVE, so a missing column must
     // be distinguished from a present 0 — an absent status means "just confirmed".
     val status = if (isNull(EventDetailProjection.IDX_STATUS)) {
@@ -84,7 +100,7 @@ internal fun ColumnReader.toEventDetailCore(
         organizer = getString(EventDetailProjection.IDX_ORGANIZER),
         attendees = attendees,
         rrule = getString(EventDetailProjection.IDX_RRULE),
-        reminders = reminders,
+        reminders = displayReminders,
         status = status,
         // BUSY and DEFAULT are both 0, so a null column folds into the same
         // default these mappers already return — no isNull guard needed.

app/src/main/java/de/jeanlucmakiola/calendula/data/prefs/SettingsPrefs.kt

@@ -4,6 +4,7 @@ import androidx.datastore.core.DataStore
 import androidx.datastore.preferences.core.Preferences
 import androidx.datastore.preferences.core.booleanPreferencesKey
 import androidx.datastore.preferences.core.edit
+import androidx.datastore.preferences.core.intPreferencesKey
 import androidx.datastore.preferences.core.stringPreferencesKey
 import de.jeanlucmakiola.calendula.domain.EventFormField
 import kotlinx.coroutines.flow.Flow
@@ -127,6 +128,97 @@ class SettingsPrefs @Inject constructor(
         store.edit { it[REMINDER_ONBOARDING_KEY] = true }
     }
 
+    /**
+     * The default reminder lead time (minutes before start) prefilled on new
+     * **timed** events. `null` = no default reminder — the prior behaviour, kept
+     * as the factory default so existing users aren't surprised by reminders they
+     * never asked for. Stored as a string so "none" is distinct from a numeric
+     * value (and from an unset key, which is also "none"). Per-calendar overrides
+     * in [perCalendarReminderOverride] take precedence; all-day events instead use
+     * [defaultAllDayReminderMinutes]. Resolve with [resolveDefaultReminder].
+     */
+    val defaultReminderMinutes: Flow<Int?> = store.data.map { prefs ->
+        prefs[DEFAULT_REMINDER_KEY].toReminderMinutes()
+    }
+
+    suspend fun setDefaultReminderMinutes(minutes: Int?) {
+        store.edit { it[DEFAULT_REMINDER_KEY] = minutes?.toString() ?: NONE }
+    }
+
+    /**
+     * The default reminder lead time prefilled on new **all-day** events, in
+     * minutes before the start of the day. All-day events want day-scale lead
+     * times ("1 day before"), so they have their own default rather than reusing
+     * the timed one. `null` = no default. Per-calendar overrides do **not** apply
+     * to all-day events — they always use this global value.
+     */
+    val defaultAllDayReminderMinutes: Flow<Int?> = store.data.map { prefs ->
+        prefs[DEFAULT_ALLDAY_REMINDER_KEY].toReminderMinutes()
+    }
+
+    suspend fun setDefaultAllDayReminderMinutes(minutes: Int?) {
+        store.edit { it[DEFAULT_ALLDAY_REMINDER_KEY] = minutes?.toString() ?: NONE }
+    }
+
+    /**
+     * Wall-clock time, as minutes from local midnight, at which **all-day**
+     * reminders fire. All-day events live at UTC midnight, so a raw "1 day
+     * before" would fire at an off hour (02:00 local in CEST); this time is
+     * encoded into the provider offset so the reminder lands at, e.g., 09:00 the
+     * day before instead. Global for every all-day reminder; default 09:00.
+     * Stored/clamped to a valid 0..1439 minute-of-day.
+     */
+    val allDayReminderTimeMinutes: Flow<Int> = store.data.map { prefs ->
+        (prefs[ALLDAY_REMINDER_TIME_KEY] ?: DEFAULT_ALLDAY_REMINDER_TIME)
+            .coerceIn(0, MINUTES_PER_DAY - 1)
+    }
+
+    suspend fun setAllDayReminderTimeMinutes(minutesOfDay: Int) {
+        store.edit { it[ALLDAY_REMINDER_TIME_KEY] = minutesOfDay.coerceIn(0, MINUTES_PER_DAY - 1) }
+    }
+
+    /**
+     * Per-calendar overrides of [defaultReminderMinutes] for **timed** events,
+     * keyed by calendar id. A calendar **present** in the map overrides the global
+     * timed default for its new events: a `null` value means "no reminder", an int
+     * means that lead time. A calendar **absent** from the map inherits the global
+     * default. Serialised as `id=value;id=value`, with `none` for an explicit
+     * no-reminder override. (All-day events ignore this and use
+     * [defaultAllDayReminderMinutes].)
+     */
+    val perCalendarReminderOverride: Flow<Map<Long, Int?>> = store.data.map { prefs ->
+        parseReminderOverrides(prefs[CALENDAR_REMINDER_OVERRIDE_KEY])
+    }
+
+    suspend fun setCalendarReminderOverride(calendarId: Long, override: CalendarReminderOverride) {
+        store.edit { prefs ->
+            val current = parseReminderOverrides(prefs[CALENDAR_REMINDER_OVERRIDE_KEY]).toMutableMap()
+            current.applyOverride(calendarId, override)
+            prefs[CALENDAR_REMINDER_OVERRIDE_KEY] = serializeReminderOverrides(current)
+        }
+    }
+
+    /**
+     * Per-calendar overrides of [defaultAllDayReminderMinutes] for **all-day**
+     * events, with the same semantics as [perCalendarReminderOverride] (absent =
+     * inherit the global all-day default; present null = no reminder).
+     */
+    val perCalendarAllDayReminderOverride: Flow<Map<Long, Int?>> = store.data.map { prefs ->
+        parseReminderOverrides(prefs[CALENDAR_ALLDAY_REMINDER_OVERRIDE_KEY])
+    }
+
+    suspend fun setCalendarAllDayReminderOverride(
+        calendarId: Long,
+        override: CalendarReminderOverride,
+    ) {
+        store.edit { prefs ->
+            val current =
+                parseReminderOverrides(prefs[CALENDAR_ALLDAY_REMINDER_OVERRIDE_KEY]).toMutableMap()
+            current.applyOverride(calendarId, override)
+            prefs[CALENDAR_ALLDAY_REMINDER_OVERRIDE_KEY] = serializeReminderOverrides(current)
+        }
+    }
+
     private fun parseFormFields(stored: String?): Set<EventFormField> = when (stored) {
         null -> DEFAULT_FORM_FIELDS
         else -> stored.split(',')
@@ -143,10 +235,90 @@ class SettingsPrefs @Inject constructor(
         internal val REMINDER_ONBOARDING_KEY = booleanPreferencesKey("reminder_onboarding_done")
         internal val ALLOW_COLOR_UNSUPPORTED_KEY =
             booleanPreferencesKey("allow_color_unsupported_calendars")
+        internal val DEFAULT_REMINDER_KEY = stringPreferencesKey("default_reminder_minutes")
+        internal val DEFAULT_ALLDAY_REMINDER_KEY =
+            stringPreferencesKey("default_allday_reminder_minutes")
+        internal val ALLDAY_REMINDER_TIME_KEY =
+            intPreferencesKey("allday_reminder_time_minutes")
+        /** 09:00 as minutes from midnight; the default all-day reminder fire time. */
+        internal const val DEFAULT_ALLDAY_REMINDER_TIME = 540
+        private const val MINUTES_PER_DAY = 1_440
+        internal val CALENDAR_REMINDER_OVERRIDE_KEY =
+            stringPreferencesKey("per_calendar_reminder_override")
+        internal val CALENDAR_ALLDAY_REMINDER_OVERRIDE_KEY =
+            stringPreferencesKey("per_calendar_allday_reminder_override")
         internal val DEFAULT_FORM_FIELDS =
             setOf(EventFormField.Location, EventFormField.Description)
     }
 }
 
+/** A calendar's reminder-default override (see [SettingsPrefs.perCalendarReminderOverride]). */
+sealed interface CalendarReminderOverride {
+    /** No override — the calendar uses the global default. */
+    data object Inherit : CalendarReminderOverride
+    /** Explicit "no reminder" for this calendar, regardless of the global default. */
+    data object None : CalendarReminderOverride
+    /** A specific lead time in minutes before the event start. */
+    data class Minutes(val minutes: Int) : CalendarReminderOverride
+}
+
+/**
+ * The lead time to prefill on a new event: the matching per-calendar override
+ * if [calendarId] has one for this event kind, otherwise the global default for
+ * that kind. All-day events consult [allDayOverrides] / [allDayGlobal]; timed
+ * events consult [timedOverrides] / [timedGlobal]. `null` = no reminder. Pure so
+ * it can be unit-tested.
+ */
+fun resolveDefaultReminder(
+    timedGlobal: Int?,
+    allDayGlobal: Int?,
+    timedOverrides: Map<Long, Int?>,
+    allDayOverrides: Map<Long, Int?>,
+    calendarId: Long?,
+    isAllDay: Boolean,
+): Int? {
+    val overrides = if (isAllDay) allDayOverrides else timedOverrides
+    val global = if (isAllDay) allDayGlobal else timedGlobal
+    return if (calendarId != null && overrides.containsKey(calendarId)) {
+        overrides[calendarId]
+    } else {
+        global
+    }
+}
+
+/** Apply a [CalendarReminderOverride] to an override map ([Inherit] removes the key). */
+private fun MutableMap<Long, Int?>.applyOverride(
+    calendarId: Long,
+    override: CalendarReminderOverride,
+) {
+    when (override) {
+        CalendarReminderOverride.Inherit -> remove(calendarId)
+        CalendarReminderOverride.None -> put(calendarId, null)
+        is CalendarReminderOverride.Minutes -> put(calendarId, override.minutes)
+    }
+}
+
+private const val NONE = "none"
+private const val ENTRY_SEP = ";"
+private const val KEY_VALUE_SEP = "="
+
+private fun String?.toReminderMinutes(): Int? = when (this) {
+    null, "", NONE -> null
+    else -> toIntOrNull()
+}
+
+private fun parseReminderOverrides(stored: String?): Map<Long, Int?> {
+    if (stored.isNullOrBlank()) return emptyMap()
+    return stored.split(ENTRY_SEP).mapNotNull { entry ->
+        val parts = entry.split(KEY_VALUE_SEP).takeIf { it.size == 2 } ?: return@mapNotNull null
+        val id = parts[0].toLongOrNull() ?: return@mapNotNull null
+        val value = if (parts[1] == NONE) null else parts[1].toIntOrNull() ?: return@mapNotNull null
+        id to value
+    }.toMap()
+}
+
+private fun serializeReminderOverrides(map: Map<Long, Int?>): String =
+    map.entries.joinToString(ENTRY_SEP) { (id, minutes) -> "$id$KEY_VALUE_SEP${minutes ?: NONE}" }
+
 private inline fun <reified E : Enum<E>> String?.toEnum(default: E): E =
     this?.let { stored -> enumValues<E>().firstOrNull { it.name == stored } } ?: default

app/src/main/java/de/jeanlucmakiola/calendula/ui/common/DialogControls.kt

@@ -0,0 +1,94 @@
+package de.jeanlucmakiola.calendula.ui.common
+
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.width
+import androidx.compose.foundation.shape.RoundedCornerShape
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.filled.ArrowDropDown
+import androidx.compose.material3.DropdownMenu
+import androidx.compose.material3.DropdownMenuItem
+import androidx.compose.material3.Icon
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Surface
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.text.input.KeyboardType
+import androidx.compose.ui.unit.dp
+
+/**
+ * Tonal 3-digit number input shared by the custom reminder/recurrence steps and
+ * the reminder pickers — the app's [InlineTextField] over a tonal surface, so it
+ * matches the card/grouped-row design language (not Material's outlined field).
+ */
+@Composable
+fun DialogAmountField(
+    value: String,
+    onValueChange: (String) -> Unit,
+    placeholder: String,
+) {
+    // surfaceContainerHighest — the picker/dialog sits on surfaceContainerHigh,
+    // so anything lower vanishes.
+    Surface(
+        color = MaterialTheme.colorScheme.surfaceContainerHighest,
+        shape = RoundedCornerShape(12.dp),
+    ) {
+        InlineTextField(
+            value = value,
+            onValueChange = { text ->
+                if (text.length <= 3 && text.all(Char::isDigit)) onValueChange(text)
+            },
+            placeholder = placeholder,
+            textStyle = MaterialTheme.typography.titleMedium,
+            keyboardType = KeyboardType.Number,
+            modifier = Modifier
+                .width(72.dp)
+                .padding(horizontal = 14.dp, vertical = 12.dp),
+        )
+    }
+}
+
+/** Tonal dropdown trigger + menu shared by the custom reminder/recurrence steps and pickers. */
+@Composable
+fun DialogUnitDropdown(
+    label: String,
+    entries: List<String>,
+    onPick: (Int) -> Unit,
+) {
+    var open by remember { mutableStateOf(false) }
+    Box {
+        Surface(
+            color = MaterialTheme.colorScheme.surfaceContainerHighest,
+            shape = RoundedCornerShape(12.dp),
+            onClick = { open = true },
+        ) {
+            Row(
+                verticalAlignment = Alignment.CenterVertically,
+                modifier = Modifier.padding(start = 14.dp, end = 8.dp, top = 12.dp, bottom = 12.dp),
+            ) {
+                Text(text = label, style = MaterialTheme.typography.titleMedium)
+                Spacer(Modifier.width(4.dp))
+                Icon(imageVector = Icons.Default.ArrowDropDown, contentDescription = null)
+            }
+        }
+        DropdownMenu(expanded = open, onDismissRequest = { open = false }) {
+            entries.forEachIndexed { index, entry ->
+                DropdownMenuItem(
+                    text = { Text(entry) },
+                    onClick = {
+                        onPick(index)
+                        open = false
+                    },
+                )
+            }
+        }
+    }
+}

app/src/main/java/de/jeanlucmakiola/calendula/ui/common/GroupedList.kt

@@ -10,7 +10,9 @@ import androidx.compose.foundation.layout.ColumnScope
 import androidx.compose.foundation.layout.RowScope
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.consumeWindowInsets
 import androidx.compose.foundation.layout.heightIn
+import androidx.compose.foundation.layout.imePadding
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.rememberScrollState
 import androidx.compose.foundation.shape.RoundedCornerShape
@@ -102,7 +104,19 @@ fun CollapsingScaffold(
         Column(
             modifier = Modifier
                 .padding(innerPadding)
+                // Mark the scaffold's system-bar insets as consumed so the
+                // imePadding below adds only the keyboard height beyond them
+                // (max, not sum) — otherwise the nav-bar inset double-counts and
+                // leaves an empty strip above the keyboard.
+                .consumeWindowInsets(innerPadding)
                 .fillMaxSize()
+                // Paint the surface across the full area before imePadding carves
+                // into it, so any sliver above the keyboard reads as surface — not
+                // the dialog window's black — during the IME animation.
+                .background(MaterialTheme.colorScheme.surface)
+                // Shrink the scroll viewport by the keyboard inset so a focused
+                // field (e.g. the custom-reminder amount) can scroll into view.
+                .imePadding()
                 .verticalScroll(rememberScrollState())
                 .padding(top = 8.dp, bottom = 24.dp),
             content = content,

app/src/main/java/de/jeanlucmakiola/calendula/ui/common/Picker.kt

@@ -0,0 +1,282 @@
+package de.jeanlucmakiola.calendula.ui.common
+
+import androidx.compose.animation.AnimatedVisibility
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.ColumnScope
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.width
+import androidx.compose.foundation.shape.RoundedCornerShape
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.filled.Check
+import androidx.compose.material3.FilledTonalButton
+import androidx.compose.material3.Icon
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.SegmentedButton
+import androidx.compose.material3.SegmentedButtonDefaults
+import androidx.compose.material3.SingleChoiceSegmentedButtonRow
+import androidx.compose.material3.Surface
+import androidx.compose.material3.Text
+import android.view.WindowManager
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.SideEffect
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.saveable.rememberSaveable
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.platform.LocalView
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.unit.dp
+import androidx.compose.ui.window.Dialog
+import androidx.compose.ui.window.DialogProperties
+import androidx.compose.ui.window.DialogWindowProvider
+import de.jeanlucmakiola.calendula.R
+import de.jeanlucmakiola.calendula.data.prefs.CalendarReminderOverride
+
+/**
+ * Shared full-screen scaffold for selection pickers: a full-bleed [Dialog] that
+ * reuses the app's [CollapsingScaffold] (collapsing title + back button), so a
+ * picker is visually identical to a Settings sub-page and uses the full width.
+ * [content] places the connected grouped rows; selecting one calls [onDismiss].
+ */
+@Composable
+fun FullScreenPicker(
+    title: String,
+    onDismiss: () -> Unit,
+    content: @Composable ColumnScope.() -> Unit,
+) {
+    Dialog(
+        onDismissRequest = onDismiss,
+        properties = DialogProperties(
+            usePlatformDefaultWidth = false,
+            decorFitsSystemWindows = false,
+        ),
+    ) {
+        // The dialog window pans by default when the keyboard opens, which —
+        // combined with the content's own imePadding — leaves a fixed black gap
+        // above the keyboard. Switch it to ADJUST_NOTHING so the window stays
+        // full-screen and imePadding alone lifts the focused field.
+        val view = LocalView.current
+        SideEffect {
+            (view.parent as? DialogWindowProvider)?.window
+                ?.setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_ADJUST_NOTHING)
+        }
+        CollapsingScaffold(title = title, onBack = onDismiss, content = content)
+    }
+}
+
+/**
+ * General single-select picker, full-screen: each option is a connected grouped
+ * row and the current one carries a check. Drop-in for the former dialog
+ * (theme, week start, language, …).
+ */
+@Composable
+fun <T> OptionPicker(
+    title: String,
+    options: List<T>,
+    selected: T,
+    label: @Composable (T) -> String,
+    onSelect: (T) -> Unit,
+    onDismiss: () -> Unit,
+) {
+    FullScreenPicker(title = title, onDismiss = onDismiss) {
+        options.forEachIndexed { index, option ->
+            val isSelected = option == selected
+            GroupedRow(
+                title = label(option),
+                position = positionOf(index, options.size),
+                selected = isSelected,
+                trailing = if (isSelected) {
+                    { SelectedCheck() }
+                } else {
+                    null
+                },
+                onClick = {
+                    onSelect(option)
+                    onDismiss()
+                },
+            )
+        }
+    }
+}
+
+/**
+ * Reminder-default picker, full-screen: the grouped list (with an optional "Use
+ * default reminder" row and a "None" row), the [presets] as lead-time rows, and
+ * a "Custom" row that expands an inline number field plus a segmented unit
+ * selector. Returns the choice as a [CalendarReminderOverride].
+ */
+@Composable
+fun ReminderDefaultPicker(
+    title: String,
+    presets: List<Int>,
+    selected: CalendarReminderOverride,
+    allowInherit: Boolean,
+    onSelect: (CalendarReminderOverride) -> Unit,
+    onDismiss: () -> Unit,
+) {
+    val selectedMinutes = (selected as? CalendarReminderOverride.Minutes)?.minutes
+    val customSelected = selectedMinutes != null && selectedMinutes !in presets
+    val seed = decomposeReminder(selectedMinutes?.takeIf { customSelected })
+
+    var customExpanded by rememberSaveable { mutableStateOf(false) }
+    var amountText by rememberSaveable { mutableStateOf(seed.first) }
+    var unit by rememberSaveable { mutableStateOf(seed.second) }
+
+    val options = buildList {
+        if (allowInherit) add(CalendarReminderOverride.Inherit)
+        add(CalendarReminderOverride.None)
+        presets.forEach { add(CalendarReminderOverride.Minutes(it)) }
+    }
+    val rowCount = options.size + 1 // + the custom row
+
+    FullScreenPicker(title = title, onDismiss = onDismiss) {
+        options.forEachIndexed { index, option ->
+            val isSelected = option == selected
+            GroupedRow(
+                title = reminderOverrideLabel(option),
+                position = positionOf(index, rowCount),
+                selected = isSelected,
+                trailing = if (isSelected) {
+                    { SelectedCheck() }
+                } else {
+                    null
+                },
+                onClick = {
+                    onSelect(option)
+                    onDismiss()
+                },
+            )
+        }
+        // When expanded, the Custom row connects downward into the editor card
+        // so the two read as one grouped container (the per-calendar pattern).
+        GroupedRow(
+            title = if (customSelected) {
+                stringResource(
+                    R.string.reminder_custom_with_value,
+                    reminderLeadTimeLabel(selectedMinutes!!),
+                )
+            } else {
+                stringResource(R.string.event_edit_reminder_custom)
+            },
+            position = if (customExpanded) Position.Top else positionOf(options.size, rowCount),
+            selected = customSelected,
+            trailing = if (customSelected) {
+                { SelectedCheck() }
+            } else {
+                null
+            },
+            onClick = { customExpanded = !customExpanded },
+        )
+        AnimatedVisibility(visible = customExpanded) {
+            CustomReminderEditor(
+                amountText = amountText,
+                onAmountChange = { amountText = it },
+                unit = unit,
+                onUnitChange = { unit = it },
+                onConfirm = { minutes ->
+                    onSelect(CalendarReminderOverride.Minutes(minutes))
+                    onDismiss()
+                },
+            )
+        }
+    }
+}
+
+/**
+ * The expanded "Custom" lead-time editor: a tonal card connected to the Custom
+ * row above it (matching the grouped-row system, so the two read as one
+ * container). An amount field with a live preview of the resulting lead time, a
+ * single-choice unit toggle, and a tonal confirm enabled only for a valid
+ * 1–999 amount. [onConfirm] receives the final lead time in minutes.
+ */
+@Composable
+private fun CustomReminderEditor(
+    amountText: String,
+    onAmountChange: (String) -> Unit,
+    unit: ReminderUnit,
+    onUnitChange: (ReminderUnit) -> Unit,
+    onConfirm: (Int) -> Unit,
+) {
+    val amount = amountText.toIntOrNull()?.takeIf { it in 1..999 }
+    Surface(
+        color = MaterialTheme.colorScheme.surfaceContainerHigh,
+        // A Position.Bottom shape: tight top corners meeting the row, full bottom.
+        shape = RoundedCornerShape(topStart = 6.dp, topEnd = 6.dp, bottomStart = 22.dp, bottomEnd = 22.dp),
+        modifier = Modifier
+            .fillMaxWidth()
+            .padding(horizontal = 16.dp),
+    ) {
+        Column(
+            modifier = Modifier.padding(16.dp),
+            verticalArrangement = Arrangement.spacedBy(16.dp),
+        ) {
+            // Unit toggle first so it stays visible above the keyboard once the
+            // amount field (the bottom row) is focused and scrolled into view.
+            SingleChoiceSegmentedButtonRow(modifier = Modifier.fillMaxWidth()) {
+                ReminderUnit.entries.forEachIndexed { index, entry ->
+                    SegmentedButton(
+                        selected = unit == entry,
+                        onClick = { onUnitChange(entry) },
+                        shape = SegmentedButtonDefaults.itemShape(index, ReminderUnit.entries.size),
+                        label = { Text(stringResource(reminderUnitLabel(entry))) },
+                    )
+                }
+            }
+            // Amount, a live preview of the lead time it resolves to, and Set —
+            // all on one row, sitting just above the keyboard.
+            Row(verticalAlignment = Alignment.CenterVertically) {
+                DialogAmountField(
+                    value = amountText,
+                    onValueChange = onAmountChange,
+                    placeholder = "10",
+                )
+                Spacer(Modifier.width(16.dp))
+                Text(
+                    text = amount?.let { reminderLeadTimeLabel(it * unit.minutesFactor) }
+                        ?: stringResource(R.string.reminder_custom_amount),
+                    style = MaterialTheme.typography.bodyLarge,
+                    color = MaterialTheme.colorScheme.onSurfaceVariant,
+                    modifier = Modifier.weight(1f),
+                )
+                Spacer(Modifier.width(16.dp))
+                FilledTonalButton(
+                    onClick = { amount?.let { onConfirm(it * unit.minutesFactor) } },
+                    enabled = amount != null,
+                ) {
+                    Text(stringResource(R.string.reminder_custom_set))
+                }
+            }
+        }
+    }
+}
+
+@Composable
+private fun SelectedCheck() {
+    Icon(
+        imageVector = Icons.Default.Check,
+        contentDescription = null,
+        tint = MaterialTheme.colorScheme.primary,
+    )
+}
+
+@Composable
+private fun reminderOverrideLabel(override: CalendarReminderOverride): String = when (override) {
+    CalendarReminderOverride.Inherit -> stringResource(R.string.reminder_use_default)
+    CalendarReminderOverride.None -> stringResource(R.string.reminder_none)
+    is CalendarReminderOverride.Minutes -> reminderLeadTimeLabel(override.minutes)
+}
+
+/** Seed the custom editor: the largest exact unit for [minutes] (null → empty). */
+private fun decomposeReminder(minutes: Int?): Pair<String, ReminderUnit> = when {
+    minutes == null -> "" to ReminderUnit.Minutes
+    minutes % 10_080 == 0 -> (minutes / 10_080).toString() to ReminderUnit.Weeks
+    minutes % 1_440 == 0 -> (minutes / 1_440).toString() to ReminderUnit.Days
+    minutes % 60 == 0 -> (minutes / 60).toString() to ReminderUnit.Hours
+    else -> minutes.toString() to ReminderUnit.Minutes
+}

app/src/main/java/de/jeanlucmakiola/calendula/ui/common/ReminderFormatting.kt

@@ -0,0 +1,46 @@
+package de.jeanlucmakiola.calendula.ui.common
+
+import androidx.annotation.StringRes
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.res.pluralStringResource
+import androidx.compose.ui.res.stringResource
+import de.jeanlucmakiola.calendula.R
+
+/** Common reminder lead times offered as quick picks in the form and settings. */
+val REMINDER_PRESETS = listOf(0, 10, 30, 60, 1_440)
+
+/** The unit of a custom reminder lead time; [minutesFactor] converts to minutes. */
+enum class ReminderUnit(val minutesFactor: Int) {
+    Minutes(1),
+    Hours(60),
+    Days(1_440),
+    Weeks(10_080),
+}
+
+@StringRes
+fun reminderUnitLabel(unit: ReminderUnit): Int = when (unit) {
+    ReminderUnit.Minutes -> R.string.reminder_unit_minutes
+    ReminderUnit.Hours -> R.string.reminder_unit_hours
+    ReminderUnit.Days -> R.string.reminder_unit_days
+    ReminderUnit.Weeks -> R.string.reminder_unit_weeks
+}
+
+/**
+ * Humanise a reminder lead time (minutes before the event start) into one
+ * line: "Default reminder" (negative = the provider default), "At time of
+ * event" (0), "10 minutes before", "1 hour before", … Shared by the detail
+ * screen, the event form and the default-reminder settings so the wording
+ * never drifts.
+ */
+@Composable
+fun reminderLeadTimeLabel(minutes: Int): String = when {
+    minutes < 0 -> stringResource(R.string.reminder_default)
+    minutes == 0 -> stringResource(R.string.reminder_at_time)
+    minutes % 10_080 == 0 ->
+        pluralStringResource(R.plurals.reminder_weeks, minutes / 10_080, minutes / 10_080)
+    minutes % 1_440 == 0 ->
+        pluralStringResource(R.plurals.reminder_days, minutes / 1_440, minutes / 1_440)
+    minutes % 60 == 0 ->
+        pluralStringResource(R.plurals.reminder_hours, minutes / 60, minutes / 60)
+    else -> pluralStringResource(R.plurals.reminder_minutes, minutes, minutes)
+}

app/src/main/java/de/jeanlucmakiola/calendula/ui/common/TimePickerAlert.kt

@@ -0,0 +1,68 @@
+package de.jeanlucmakiola.calendula.ui.common
+
+import androidx.compose.material3.AlertDialog
+import androidx.compose.material3.ExperimentalMaterial3Api
+import androidx.compose.material3.Text
+import androidx.compose.material3.TextButton
+import android.content.Context
+import android.content.res.Resources
+import android.provider.Settings
+import android.text.format.DateFormat
+import androidx.compose.material3.TimePicker
+import androidx.compose.material3.rememberTimePickerState
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.platform.LocalContext
+import androidx.compose.ui.res.stringResource
+import de.jeanlucmakiola.calendula.R
+import kotlinx.datetime.LocalTime
+
+/**
+ * M3 time picker in an alert dialog, seeded with [initial]. Shared by the event
+ * form (start/end times) and Settings (the all-day reminder fire time).
+ */
+@OptIn(ExperimentalMaterial3Api::class)
+@Composable
+fun TimePickerAlert(
+    initial: LocalTime,
+    onConfirm: (LocalTime) -> Unit,
+    onDismiss: () -> Unit,
+) {
+    val state = rememberTimePickerState(
+        initialHour = initial.hour,
+        initialMinute = initial.minute,
+        is24Hour = deviceUses24HourClock(LocalContext.current),
+    )
+    AlertDialog(
+        onDismissRequest = onDismiss,
+        confirmButton = {
+            TextButton(onClick = { onConfirm(LocalTime(state.hour, state.minute)) }) {
+                Text(stringResource(R.string.dialog_ok))
+            }
+        },
+        dismissButton = {
+            TextButton(onClick = onDismiss) { Text(stringResource(R.string.dialog_cancel)) }
+        },
+        text = { TimePicker(state = state) },
+    )
+}
+
+/**
+ * Whether the clock should read 24-hour, matching the rest of the device.
+ *
+ * [DateFormat.is24HourFormat] resolves a "locale default" system setting against
+ * the *app's* context locale — and this app applies a per-app language
+ * (AppCompatDelegate), so an English UI on a German-region phone would wrongly
+ * read 12-hour while the system clock shows 24-hour. So we honour an explicit
+ * system 12/24 override, and otherwise fall back to the **device** locale
+ * (Resources.getSystem), not the app's.
+ */
+private fun deviceUses24HourClock(context: Context): Boolean =
+    when (Settings.System.getString(context.contentResolver, Settings.System.TIME_12_24)) {
+        "24" -> true
+        "12" -> false
+        // 'a' is the AM/PM marker; a best-fit pattern without it is 24-hour.
+        else -> {
+            val deviceLocale = Resources.getSystem().configuration.locales[0]
+            !DateFormat.getBestDateTimePattern(deviceLocale, "jm").contains('a')
+        }
+    }

app/src/main/java/de/jeanlucmakiola/calendula/ui/detail/EventDetailScreen.kt

@@ -67,7 +67,6 @@ import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.graphics.vector.ImageVector
 import androidx.compose.ui.platform.LocalContext
 import androidx.core.content.ContextCompat
-import androidx.compose.ui.res.pluralStringResource
 import androidx.compose.ui.res.stringResource
 import androidx.compose.ui.text.AnnotatedString
 import androidx.compose.ui.text.LinkAnnotation
@@ -96,6 +95,7 @@ import de.jeanlucmakiola.calendula.ui.common.OptionCard
 import de.jeanlucmakiola.calendula.ui.common.currentLocale
 import de.jeanlucmakiola.calendula.ui.common.pastelize
 import de.jeanlucmakiola.calendula.ui.common.recurrenceText
+import de.jeanlucmakiola.calendula.ui.common.reminderLeadTimeLabel
 import kotlinx.datetime.TimeZone
 import java.time.ZoneId
 import java.time.format.DateTimeFormatter
@@ -684,26 +684,7 @@ private fun attendeeRoleLabel(attendee: Attendee): Int? = when {
 
 /** Humanise a reminder's lead time, e.g. "10 minutes before" / "At time of event". */
 @Composable
-private fun reminderLeadText(reminder: Reminder): String {
-    val minutes = reminder.minutes
-    return when {
-        minutes < 0 -> stringResource(R.string.reminder_default)
-        minutes == 0 -> stringResource(R.string.reminder_at_time)
-        minutes % 10_080 == 0 -> {
-            val weeks = minutes / 10_080
-            pluralStringResource(R.plurals.reminder_weeks, weeks, weeks)
-        }
-        minutes % 1_440 == 0 -> {
-            val days = minutes / 1_440
-            pluralStringResource(R.plurals.reminder_days, days, days)
-        }
-        minutes % 60 == 0 -> {
-            val hours = minutes / 60
-            pluralStringResource(R.plurals.reminder_hours, hours, hours)
-        }
-        else -> pluralStringResource(R.plurals.reminder_minutes, minutes, minutes)
-    }
-}
+private fun reminderLeadText(reminder: Reminder): String = reminderLeadTimeLabel(reminder.minutes)
 
 /**
  * A localized label for [tz] (e.g. "Central European Time (Europe/Berlin)"),

app/src/main/java/de/jeanlucmakiola/calendula/ui/edit/EventEditScreen.kt

@@ -68,10 +68,8 @@ import androidx.compose.material3.Surface
 import androidx.compose.material3.Switch
 import androidx.compose.material3.Text
 import androidx.compose.material3.TextButton
-import androidx.compose.material3.TimePicker
 import androidx.compose.material3.TopAppBar
 import androidx.compose.material3.TopAppBarDefaults
-import androidx.compose.material3.rememberTimePickerState
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.getValue
@@ -86,7 +84,6 @@ import androidx.compose.ui.graphics.SolidColor
 import androidx.compose.ui.graphics.isSpecified
 import androidx.compose.ui.graphics.vector.ImageVector
 import androidx.compose.ui.platform.LocalContext
-import androidx.compose.ui.res.pluralStringResource
 import androidx.compose.ui.res.stringResource
 import androidx.compose.ui.text.AnnotatedString
 import androidx.compose.ui.text.TextStyle
@@ -112,10 +109,17 @@ import de.jeanlucmakiola.calendula.domain.toRRule
 import de.jeanlucmakiola.calendula.ui.common.CALENDAR_COLOR_PALETTE
 import de.jeanlucmakiola.calendula.ui.common.CalendarDatePickerDialog
 import de.jeanlucmakiola.calendula.ui.common.ColorSwatchRow
+import de.jeanlucmakiola.calendula.ui.common.DialogAmountField
+import de.jeanlucmakiola.calendula.ui.common.DialogUnitDropdown
 import de.jeanlucmakiola.calendula.ui.common.MILLIS_PER_DAY
 import de.jeanlucmakiola.calendula.ui.common.InlineTextField
 import de.jeanlucmakiola.calendula.ui.common.OptionCard
+import de.jeanlucmakiola.calendula.ui.common.REMINDER_PRESETS
+import de.jeanlucmakiola.calendula.ui.common.ReminderUnit
+import de.jeanlucmakiola.calendula.ui.common.TimePickerAlert
 import de.jeanlucmakiola.calendula.ui.common.currentLocale
+import de.jeanlucmakiola.calendula.ui.common.reminderLeadTimeLabel
+import de.jeanlucmakiola.calendula.ui.common.reminderUnitLabel
 import de.jeanlucmakiola.calendula.ui.common.pastelize
 import de.jeanlucmakiola.calendula.ui.common.recurrenceText
 import kotlinx.datetime.DayOfWeek
@@ -916,14 +920,7 @@ private fun FieldPickerDialog(
 }
 
 /** Quick-pick lead times offered as chips in the reminder dialog. */
-private val REMINDER_QUICK_PICKS = listOf(0, 10, 30, 60, 1_440)
-
-private enum class ReminderUnit(val minutesFactor: Int) {
-    Minutes(1),
-    Hours(60),
-    Days(1_440),
-    Weeks(10_080),
-}
+private val REMINDER_QUICK_PICKS = REMINDER_PRESETS
 
 /**
  * Reminder picker, two steps: the common lead times as a tappable list
@@ -1245,84 +1242,6 @@ private fun Set<DayOfWeek>.toMask(): Int = fold(0) { acc, day -> acc or day.toMa
 private fun Int.toDaySet(): Set<DayOfWeek> =
     DayOfWeek.entries.filter { this and it.toMaskBit() != 0 }.toSet()
 
-/** Tonal 3-digit number input shared by the custom reminder/recurrence steps. */
-@Composable
-private fun DialogAmountField(
-    value: String,
-    onValueChange: (String) -> Unit,
-    placeholder: String,
-) {
-    // surfaceContainerHighest — the dialog itself sits on
-    // surfaceContainerHigh, so anything lower vanishes.
-    Surface(
-        color = MaterialTheme.colorScheme.surfaceContainerHighest,
-        shape = RoundedCornerShape(12.dp),
-    ) {
-        InlineField(
-            value = value,
-            onValueChange = { text ->
-                if (text.length <= 3 && text.all(Char::isDigit)) {
-                    onValueChange(text)
-                }
-            },
-            placeholder = placeholder,
-            textStyle = MaterialTheme.typography.titleMedium,
-            keyboardType = KeyboardType.Number,
-            modifier = Modifier
-                .width(72.dp)
-                .padding(horizontal = 14.dp, vertical = 12.dp),
-        )
-    }
-}
-
-/** Tonal dropdown trigger + menu shared by the custom reminder/recurrence steps. */
-@Composable
-private fun DialogUnitDropdown(
-    label: String,
-    entries: List<String>,
-    onPick: (Int) -> Unit,
-) {
-    var open by remember { mutableStateOf(false) }
-    Box {
-        Surface(
-            color = MaterialTheme.colorScheme.surfaceContainerHighest,
-            shape = RoundedCornerShape(12.dp),
-            onClick = { open = true },
-        ) {
-            Row(
-                verticalAlignment = Alignment.CenterVertically,
-                modifier = Modifier.padding(
-                    start = 14.dp,
-                    end = 8.dp,
-                    top = 12.dp,
-                    bottom = 12.dp,
-                ),
-            ) {
-                Text(
-                    text = label,
-                    style = MaterialTheme.typography.titleMedium,
-                )
-                Spacer(Modifier.width(4.dp))
-                Icon(
-                    imageVector = Icons.Default.ArrowDropDown,
-                    contentDescription = null,
-                    tint = MaterialTheme.colorScheme.onSurfaceVariant,
-                )
-            }
-        }
-        DropdownMenu(expanded = open, onDismissRequest = { open = false }) {
-            entries.forEachIndexed { index, entry ->
-                DropdownMenuItem(
-                    text = { Text(entry) },
-                    onClick = {
-                        onPick(index)
-                        open = false
-                    },
-                )
-            }
-        }
-    }
-}
 
 private fun recurrencePresetLabel(freq: RecurrenceFreq): Int = when (freq) {
     RecurrenceFreq.Daily -> R.string.recurrence_daily
@@ -1377,13 +1296,6 @@ private fun AddReminderChip(onClick: () -> Unit) {
     )
 }
 
-private fun reminderUnitLabel(unit: ReminderUnit): Int = when (unit) {
-    ReminderUnit.Minutes -> R.string.reminder_unit_minutes
-    ReminderUnit.Hours -> R.string.reminder_unit_hours
-    ReminderUnit.Days -> R.string.reminder_unit_days
-    ReminderUnit.Weeks -> R.string.reminder_unit_weeks
-}
-
 private fun fieldLabel(field: EventFormField): Int = when (field) {
     EventFormField.Location -> R.string.event_detail_location
     EventFormField.Description -> R.string.event_detail_description
@@ -1517,16 +1429,7 @@ private fun accessLevelLabel(level: AccessLevel): Int = when (level) {
 
 /** Humanise a reminder lead time, mirroring the detail screen's rendering. */
 @Composable
-private fun reminderLabel(minutes: Int): String = when {
-    minutes <= 0 -> stringResource(R.string.reminder_at_time)
-    minutes % 10_080 == 0 ->
-        pluralStringResource(R.plurals.reminder_weeks, minutes / 10_080, minutes / 10_080)
-    minutes % 1_440 == 0 ->
-        pluralStringResource(R.plurals.reminder_days, minutes / 1_440, minutes / 1_440)
-    minutes % 60 == 0 ->
-        pluralStringResource(R.plurals.reminder_hours, minutes / 60, minutes / 60)
-    else -> pluralStringResource(R.plurals.reminder_minutes, minutes, minutes)
-}
+private fun reminderLabel(minutes: Int): String = reminderLeadTimeLabel(minutes)
 
 /**
  * One info card mirroring the detail screen's DetailCard: tonal container,
@@ -1687,31 +1590,6 @@ private fun ScheduleRow(
     }
 }
 
-@OptIn(ExperimentalMaterial3Api::class)
-@Composable
-private fun TimePickerAlert(
-    initial: LocalTime,
-    onConfirm: (LocalTime) -> Unit,
-    onDismiss: () -> Unit,
-) {
-    val state = rememberTimePickerState(
-        initialHour = initial.hour,
-        initialMinute = initial.minute,
-    )
-    AlertDialog(
-        onDismissRequest = onDismiss,
-        confirmButton = {
-            TextButton(onClick = { onConfirm(LocalTime(state.hour, state.minute)) }) {
-                Text(stringResource(R.string.dialog_ok))
-            }
-        },
-        dismissButton = {
-            TextButton(onClick = onDismiss) { Text(stringResource(R.string.dialog_cancel)) }
-        },
-        text = { TimePicker(state = state) },
-    )
-}
-
 @Composable
 private fun CalendarPickerDialog(
     calendars: List<CalendarSource>,

app/src/main/java/de/jeanlucmakiola/calendula/ui/edit/EventEditViewModel.kt

@@ -8,6 +8,7 @@ import de.jeanlucmakiola.calendula.data.calendar.NoSuchEventException
 import de.jeanlucmakiola.calendula.data.di.IoDispatcher
 import de.jeanlucmakiola.calendula.data.prefs.CalendarPrefs
 import de.jeanlucmakiola.calendula.data.prefs.SettingsPrefs
+import de.jeanlucmakiola.calendula.data.prefs.resolveDefaultReminder
 import de.jeanlucmakiola.calendula.domain.AccessLevel
 import de.jeanlucmakiola.calendula.domain.Availability
 import de.jeanlucmakiola.calendula.domain.CalendarSource
@@ -29,6 +30,7 @@ import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.catch
 import kotlinx.coroutines.flow.combine
 import kotlinx.coroutines.flow.distinctUntilChanged
+import kotlinx.coroutines.flow.first
 import kotlinx.coroutines.flow.flatMapLatest
 import kotlinx.coroutines.flow.flow
 import kotlinx.coroutines.flow.flowOn
@@ -71,6 +73,10 @@ class EventEditViewModel @Inject constructor(
     // Set while the form edits an existing event instead of composing a new one.
     private val _editTarget = MutableStateFlow<EditTarget?>(null)
     private val _loadFailed = MutableStateFlow(false)
+    // True once the user has hand-edited the reminders on a new event, which
+    // freezes the auto-applied default: switching calendars no longer overwrites
+    // their choice. Reset with the form.
+    private val _remindersTouched = MutableStateFlow(false)
 
     /** True when the event to edit couldn't be loaded; the screen closes itself. */
     val loadFailed: StateFlow<Boolean> = _loadFailed.asStateFlow()
@@ -100,6 +106,13 @@ class EventEditViewModel @Inject constructor(
         val editTarget: EditTarget?,
     )
 
+    private data class ReminderDefaults(
+        val timed: Int?,
+        val allDay: Int?,
+        val timedOverrides: Map<Long, Int?>,
+        val allDayOverrides: Map<Long, Int?>,
+    )
+
     private data class ExternalInputs(
         val writable: List<CalendarSource>,
         val lastUsed: Long?,
@@ -194,6 +207,48 @@ class EventEditViewModel @Inject constructor(
         }
         val end = (start.toInstant(zone) + 1.hours).toLocalDateTime(zone)
         _form.value = EventForm(calendarId = null, start = start, end = end)
+        applyDefaultReminder()
+    }
+
+    /**
+     * Prefill a new event's reminders from the settings default — the all-day
+     * default for all-day events, otherwise the resolved calendar's per-calendar
+     * override or the global timed default. No-op while editing an existing event
+     * or once the user has hand-edited the reminders, so the auto-default never
+     * clobbers a manual choice. [calendarId] short-circuits the resolution after a
+     * calendar switch; null resolves it as the form does.
+     */
+    private fun applyDefaultReminder(calendarId: Long? = null) {
+        if (_editTarget.value != null || _remindersTouched.value) return
+        viewModelScope.launch {
+            val defaults = combine(
+                settingsPrefs.defaultReminderMinutes,
+                settingsPrefs.defaultAllDayReminderMinutes,
+                settingsPrefs.perCalendarReminderOverride,
+                settingsPrefs.perCalendarAllDayReminderOverride,
+            ) { timed, allDay, timedOv, allDayOv ->
+                ReminderDefaults(timed, allDay, timedOv, allDayOv)
+            }.first()
+            val targetId = calendarId ?: resolvedCalendarId.first()
+            // Re-check after suspending: bail if the form closed or the user edited.
+            val form = _form.value ?: return@launch
+            if (_editTarget.value != null || _remindersTouched.value) return@launch
+            val default = resolveDefaultReminder(
+                timedGlobal = defaults.timed,
+                allDayGlobal = defaults.allDay,
+                timedOverrides = defaults.timedOverrides,
+                allDayOverrides = defaults.allDayOverrides,
+                calendarId = targetId,
+                isAllDay = form.isAllDay,
+            )
+            val reminders = listOfNotNull(default)
+            _form.value = form.copy(reminders = reminders)
+            // Surface the section so an auto-applied default is visible and
+            // removable, even when Reminders isn't a default-shown field.
+            if (reminders.isNotEmpty()) {
+                _revealed.value = _revealed.value + EventFormField.Reminders
+            }
+        }
     }
 
     /**
@@ -229,6 +284,7 @@ class EventEditViewModel @Inject constructor(
         _revealed.value = emptySet()
         _editTarget.value = null
         _loadFailed.value = false
+        _remindersTouched.value = false
     }
 
     /** Unfold one optional field, picked in the "more fields" dialog. */
@@ -239,14 +295,24 @@ class EventEditViewModel @Inject constructor(
     fun setTitle(value: String) = update { it.copy(title = value) }
     fun setLocation(value: String) = update { it.copy(location = value) }
     fun setDescription(value: String) = update { it.copy(description = value) }
-    fun setAllDay(value: Boolean) = update { it.copy(isAllDay = value) }
+    fun setAllDay(value: Boolean) {
+        update { it.copy(isAllDay = value) }
+        // The default reminder differs for all-day vs timed; re-apply the
+        // type-appropriate default unless the user has hand-edited it (guarded).
+        applyDefaultReminder()
+    }
 
     /**
      * Switching calendars drops any chosen colour: a palette key is
      * account-scoped, and a raw colour may be invalid on the new calendar.
      * The event falls back to the new calendar's colour until re-picked.
      */
-    fun setCalendar(id: Long) = update { it.copy(calendarId = id, colorKey = null, color = null) }
+    fun setCalendar(id: Long) {
+        update { it.copy(calendarId = id, colorKey = null, color = null) }
+        // A fresh event re-inherits the new calendar's default reminder unless
+        // the user has already hand-edited it (guarded inside).
+        applyDefaultReminder(id)
+    }
     fun setAvailability(value: Availability) = update { it.copy(availability = value) }
     fun setAccessLevel(value: AccessLevel) = update { it.copy(accessLevel = value) }
 
@@ -262,12 +328,14 @@ class EventEditViewModel @Inject constructor(
     /** Bare RRULE value from the recurrence picker; null = does not repeat. */
     fun setRecurrence(rrule: String?) = update { it.copy(rrule = rrule) }
 
-    fun addReminder(minutes: Int) = update {
-        it.copy(reminders = (it.reminders + minutes).distinct().sorted())
+    fun addReminder(minutes: Int) {
+        _remindersTouched.value = true
+        update { it.copy(reminders = (it.reminders + minutes).distinct().sorted()) }
     }
 
-    fun removeReminder(minutes: Int) = update {
-        it.copy(reminders = it.reminders - minutes)
+    fun removeReminder(minutes: Int) {
+        _remindersTouched.value = true
+        update { it.copy(reminders = it.reminders - minutes) }
     }
 
     /** Moving the start drags the end along, preserving the duration. */

app/src/main/java/de/jeanlucmakiola/calendula/ui/settings/SettingsScreen.kt

@@ -5,6 +5,9 @@ import android.content.Context
 import android.content.Intent
 import android.content.pm.PackageManager
 import android.os.Build
+import android.os.PowerManager
+import android.provider.Settings
+import android.text.format.DateFormat
 import androidx.activity.compose.rememberLauncherForActivityResult
 import androidx.activity.result.contract.ActivityResultContracts
 import androidx.compose.animation.AnimatedVisibility
@@ -31,20 +34,22 @@ import androidx.compose.foundation.shape.CircleShape
 import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.filled.CalendarMonth
+import androidx.compose.material.icons.filled.Check
+import androidx.compose.material.icons.filled.ExpandLess
+import androidx.compose.material.icons.filled.ExpandMore
 import androidx.compose.material.icons.filled.Gavel
 import androidx.compose.material.icons.filled.Language
 import androidx.compose.material.icons.filled.Notifications
 import androidx.compose.material.icons.filled.Palette
 import androidx.compose.material.icons.filled.Tune
-import androidx.compose.material3.AlertDialog
 import androidx.compose.material3.Icon
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.OutlinedButton
 import androidx.compose.material3.Surface
 import androidx.compose.material3.Switch
 import androidx.compose.material3.Text
-import androidx.compose.material3.TextButton
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.DisposableEffect
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
@@ -63,17 +68,28 @@ import androidx.compose.ui.unit.dp
 import androidx.core.content.ContextCompat
 import androidx.core.net.toUri
 import androidx.hilt.navigation.compose.hiltViewModel
+import androidx.lifecycle.Lifecycle
+import androidx.lifecycle.LifecycleEventObserver
+import androidx.lifecycle.compose.LocalLifecycleOwner
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import de.jeanlucmakiola.calendula.R
+import de.jeanlucmakiola.calendula.data.prefs.CalendarReminderOverride
 import de.jeanlucmakiola.calendula.data.prefs.ThemeMode
 import de.jeanlucmakiola.calendula.data.prefs.WeekStartPref
 import de.jeanlucmakiola.calendula.domain.EventFormField
 import de.jeanlucmakiola.calendula.ui.common.CollapsingScaffold
 import de.jeanlucmakiola.calendula.ui.common.GroupedRow
-import de.jeanlucmakiola.calendula.ui.common.OptionCard
+import de.jeanlucmakiola.calendula.ui.common.CalendarColorChip
+import de.jeanlucmakiola.calendula.ui.common.OptionPicker
 import de.jeanlucmakiola.calendula.ui.common.Position
+import de.jeanlucmakiola.calendula.ui.common.REMINDER_PRESETS
+import de.jeanlucmakiola.calendula.ui.common.ReminderDefaultPicker
+import de.jeanlucmakiola.calendula.ui.common.TimePickerAlert
 import de.jeanlucmakiola.calendula.ui.common.positionOf
+import de.jeanlucmakiola.calendula.ui.common.reminderLeadTimeLabel
 import de.jeanlucmakiola.calendula.ui.common.rememberCalendarSlideSpec
+import kotlinx.datetime.LocalTime
+import java.util.Calendar
 
 /** The settings sub-screens reached from the hub's category rows. */
 private enum class SettingsSection { Appearance, EventForm, Notifications }
@@ -206,7 +222,7 @@ private fun LanguageRow(position: Position) {
     )
 
     if (showDialog) {
-        OptionPickerDialog(
+        OptionPicker(
             title = stringResource(R.string.settings_language),
             options = options,
             selected = current,
@@ -382,7 +398,7 @@ private fun AppearanceScreen(
     }
 
     if (showTheme) {
-        OptionPickerDialog(
+        OptionPicker(
             title = stringResource(R.string.settings_theme),
             options = ThemeMode.entries,
             selected = state.themeMode,
@@ -392,7 +408,7 @@ private fun AppearanceScreen(
         )
     }
     if (showWeekStart) {
-        OptionPickerDialog(
+        OptionPicker(
             title = stringResource(R.string.settings_week_start),
             options = WeekStartPref.entries,
             selected = state.weekStart,
@@ -486,6 +502,12 @@ private fun NotificationsScreen(
         }
     }
 
+    var showDefaultReminder by remember { mutableStateOf(false) }
+    var showAllDayReminder by remember { mutableStateOf(false) }
+    var showAllDayReminderTime by remember { mutableStateOf(false) }
+    var overrideDialog by remember { mutableStateOf<OverrideTarget?>(null) }
+    var expandedCalendars by remember { mutableStateOf(emptySet<Long>()) }
+
     CollapsingScaffold(
         title = stringResource(R.string.settings_section_notifications),
         onBack = onBack,
@@ -493,13 +515,273 @@ private fun NotificationsScreen(
         GroupedRow(
             title = stringResource(R.string.settings_reminders),
             summary = stringResource(R.string.settings_reminders_hint),
-            position = Position.Alone,
+            position = Position.Top,
             trailing = {
                 Switch(checked = state.remindersEnabled, onCheckedChange = toggleReminders)
             },
             onClick = { toggleReminders(!state.remindersEnabled) },
         )
+        GroupedRow(
+            title = stringResource(R.string.settings_default_reminder),
+            summary = reminderChoiceLabel(state.defaultReminderMinutes),
+            position = Position.Middle,
+            onClick = { showDefaultReminder = true },
+        )
+        GroupedRow(
+            title = stringResource(R.string.settings_default_reminder_allday),
+            summary = reminderChoiceLabel(state.defaultAllDayReminderMinutes),
+            position = Position.Middle,
+            onClick = { showAllDayReminder = true },
+        )
+        GroupedRow(
+            title = stringResource(R.string.settings_allday_reminder_time),
+            summary = stringResource(
+                R.string.settings_allday_reminder_time_hint,
+                formatTimeOfDay(context, state.allDayReminderTimeMinutes),
+            ),
+            position = Position.Bottom,
+            onClick = { showAllDayReminderTime = true },
+        )
+
+        // Per-calendar overrides: each writable calendar may keep, drop, or
+        // replace the global default — separately for timed and all-day events.
+        if (state.writableCalendars.isNotEmpty()) {
+            Spacer(Modifier.height(24.dp))
+            Text(
+                text = stringResource(R.string.settings_calendar_reminders_hint),
+                style = MaterialTheme.typography.bodyMedium,
+                color = MaterialTheme.colorScheme.onSurfaceVariant,
+                modifier = Modifier.padding(horizontal = 16.dp, vertical = 4.dp),
+            )
+            state.writableCalendars.forEach { calendar ->
+                Spacer(Modifier.height(16.dp))
+                val expanded = calendar.id in expandedCalendars
+                // Calendar card; tapping expands it into a grouped list of three
+                // (the card + the timed and all-day override rows).
+                GroupedRow(
+                    title = calendar.displayName,
+                    position = if (expanded) Position.Top else Position.Alone,
+                    leading = { CalendarColorChip(calendar.color) },
+                    trailing = {
+                        Icon(
+                            imageVector = if (expanded) Icons.Default.ExpandLess else Icons.Default.ExpandMore,
+                            contentDescription = null,
+                            tint = MaterialTheme.colorScheme.onSurfaceVariant,
+                        )
+                    },
+                    onClick = {
+                        expandedCalendars = if (expanded) {
+                            expandedCalendars - calendar.id
+                        } else {
+                            expandedCalendars + calendar.id
+                        }
+                    },
+                )
+                AnimatedVisibility(visible = expanded) {
+                    Column {
+                        val timed = state.perCalendarReminderOverride.choiceFor(calendar.id)
+                        GroupedRow(
+                            title = stringResource(R.string.settings_default_reminder),
+                            summary = calendarOverrideSummary(timed, state.defaultReminderMinutes),
+                            position = Position.Middle,
+                            onClick = { overrideDialog = OverrideTarget(calendar.id, isAllDay = false) },
+                        )
+                        val allDay = state.perCalendarAllDayReminderOverride.choiceFor(calendar.id)
+                        GroupedRow(
+                            title = stringResource(R.string.settings_default_reminder_allday),
+                            summary = calendarOverrideSummary(allDay, state.defaultAllDayReminderMinutes),
+                            position = Position.Bottom,
+                            onClick = { overrideDialog = OverrideTarget(calendar.id, isAllDay = true) },
+                        )
+                    }
+                }
+            }
+        }
+
+        // Delivery reliability: Android's battery optimisation can delay or drop
+        // the calendar provider's reminder broadcast. A soft, optional exemption
+        // (system-settings deep-link, no special permission) improves on-time
+        // delivery; shown as live status, reversible by the user at any time.
+        Spacer(Modifier.height(24.dp))
+        val batteryExempt = rememberBatteryOptimizationExempt()
+        GroupedRow(
+            title = stringResource(R.string.settings_reliable_delivery),
+            summary = if (batteryExempt) {
+                stringResource(R.string.settings_reliable_delivery_exempt)
+            } else {
+                stringResource(R.string.settings_reliable_delivery_hint)
+            },
+            position = Position.Alone,
+            trailing = if (batteryExempt) {
+                {
+                    Icon(
+                        imageVector = Icons.Default.Check,
+                        contentDescription = null,
+                        tint = MaterialTheme.colorScheme.primary,
+                    )
+                }
+            } else {
+                null
+            },
+            onClick = { openBatteryOptimizationSettings(context) },
+        )
     }
+
+    if (showDefaultReminder) {
+        ReminderDefaultPicker(
+            title = stringResource(R.string.settings_default_reminder),
+            presets = REMINDER_PRESETS,
+            selected = state.defaultReminderMinutes.toReminderChoice(),
+            allowInherit = false,
+            onSelect = { viewModel.setDefaultReminderMinutes(it.toMinutesOrNull()) },
+            onDismiss = { showDefaultReminder = false },
+        )
+    }
+    if (showAllDayReminder) {
+        ReminderDefaultPicker(
+            title = stringResource(R.string.settings_default_reminder_allday),
+            presets = ALLDAY_REMINDER_PRESETS,
+            selected = state.defaultAllDayReminderMinutes.toReminderChoice(),
+            allowInherit = false,
+            onSelect = { viewModel.setDefaultAllDayReminderMinutes(it.toMinutesOrNull()) },
+            onDismiss = { showAllDayReminder = false },
+        )
+    }
+    if (showAllDayReminderTime) {
+        TimePickerAlert(
+            initial = LocalTime(
+                state.allDayReminderTimeMinutes / 60,
+                state.allDayReminderTimeMinutes % 60,
+            ),
+            onConfirm = {
+                viewModel.setAllDayReminderTimeMinutes(it.hour * 60 + it.minute)
+                showAllDayReminderTime = false
+            },
+            onDismiss = { showAllDayReminderTime = false },
+        )
+    }
+    overrideDialog?.let { target ->
+        val map = if (target.isAllDay) {
+            state.perCalendarAllDayReminderOverride
+        } else {
+            state.perCalendarReminderOverride
+        }
+        ReminderDefaultPicker(
+            title = stringResource(
+                if (target.isAllDay) {
+                    R.string.settings_default_reminder_allday
+                } else {
+                    R.string.settings_default_reminder
+                },
+            ),
+            presets = if (target.isAllDay) ALLDAY_REMINDER_PRESETS else REMINDER_PRESETS,
+            selected = map.choiceFor(target.calendarId),
+            allowInherit = true,
+            onSelect = {
+                if (target.isAllDay) {
+                    viewModel.setCalendarAllDayReminderOverride(target.calendarId, it)
+                } else {
+                    viewModel.setCalendarReminderOverride(target.calendarId, it)
+                }
+            },
+            onDismiss = { overrideDialog = null },
+        )
+    }
+}
+
+/** Which calendar + event kind a per-calendar reminder-override dialog targets. */
+private data class OverrideTarget(val calendarId: Long, val isAllDay: Boolean)
+
+/** A global default (null = none) as a picker choice for selection highlighting. */
+private fun Int?.toReminderChoice(): CalendarReminderOverride =
+    if (this == null) CalendarReminderOverride.None else CalendarReminderOverride.Minutes(this)
+
+/** A picked choice as global-default minutes (Inherit isn't offered for globals). */
+private fun CalendarReminderOverride.toMinutesOrNull(): Int? =
+    (this as? CalendarReminderOverride.Minutes)?.minutes
+
+/**
+ * Whether Calendula is exempt from battery optimisation, re-read on every
+ * `ON_RESUME` so the row reflects a change the user just made in system
+ * settings without needing to leave and re-enter the screen.
+ */
+@Composable
+private fun rememberBatteryOptimizationExempt(): Boolean {
+    val context = LocalContext.current
+    var exempt by remember { mutableStateOf(isIgnoringBatteryOptimizations(context)) }
+    val lifecycleOwner = LocalLifecycleOwner.current
+    DisposableEffect(lifecycleOwner) {
+        val observer = LifecycleEventObserver { _, event ->
+            if (event == Lifecycle.Event.ON_RESUME) {
+                exempt = isIgnoringBatteryOptimizations(context)
+            }
+        }
+        lifecycleOwner.lifecycle.addObserver(observer)
+        onDispose { lifecycleOwner.lifecycle.removeObserver(observer) }
+    }
+    return exempt
+}
+
+private fun isIgnoringBatteryOptimizations(context: Context): Boolean {
+    val power = context.getSystemService(Context.POWER_SERVICE) as PowerManager
+    return power.isIgnoringBatteryOptimizations(context.packageName)
+}
+
+/**
+ * Take the user straight to Calendula's exemption: the direct
+ * `REQUEST_IGNORE_BATTERY_OPTIMIZATIONS` dialog ("Allow Calendula to ignore
+ * battery optimisation?") rather than the full app list they'd have to scroll.
+ * Falls back to the optimisation list if the OS refuses the direct intent.
+ */
+private fun openBatteryOptimizationSettings(context: Context) {
+    val direct = Intent(
+        Settings.ACTION_REQUEST_IGNORE_BATTERY_OPTIMIZATIONS,
+        "package:${context.packageName}".toUri(),
+    )
+    if (runCatching { context.startActivity(direct) }.isFailure) {
+        runCatching {
+            context.startActivity(Intent(Settings.ACTION_IGNORE_BATTERY_OPTIMIZATION_SETTINGS))
+        }
+    }
+}
+
+/**
+ * Lead times offered for the all-day default — day-scale, since a "minutes
+ * before midnight" reminder on an all-day event is rarely what's wanted.
+ */
+private val ALLDAY_REMINDER_PRESETS = listOf(0, 1_440, 2_880, 10_080)
+
+/** A minute-of-day formatted in the device's 12/24-hour convention (e.g. "09:00"). */
+private fun formatTimeOfDay(context: Context, minutesOfDay: Int): String {
+    val time = Calendar.getInstance().apply {
+        set(Calendar.HOUR_OF_DAY, minutesOfDay / 60)
+        set(Calendar.MINUTE, minutesOfDay % 60)
+    }.time
+    return DateFormat.getTimeFormat(context).format(time)
+}
+
+/** The stored override for [calendarId], as a picker choice (absent → inherit). */
+private fun Map<Long, Int?>.choiceFor(calendarId: Long): CalendarReminderOverride = when {
+    !containsKey(calendarId) -> CalendarReminderOverride.Inherit
+    this[calendarId] == null -> CalendarReminderOverride.None
+    else -> CalendarReminderOverride.Minutes(this.getValue(calendarId)!!)
+}
+
+/** Label for a global-default choice: null → "None", else the lead time. */
+@Composable
+private fun reminderChoiceLabel(minutes: Int?): String =
+    if (minutes == null) stringResource(R.string.reminder_none) else reminderLeadTimeLabel(minutes)
+
+/** Row summary for a calendar: its override, or the inherited global default. */
+@Composable
+private fun calendarOverrideSummary(
+    choice: CalendarReminderOverride,
+    globalDefault: Int?,
+): String = when (choice) {
+    CalendarReminderOverride.Inherit ->
+        stringResource(R.string.settings_calendar_reminder_inherits, reminderChoiceLabel(globalDefault))
+    CalendarReminderOverride.None -> stringResource(R.string.reminder_none)
+    is CalendarReminderOverride.Minutes -> reminderLeadTimeLabel(choice.minutes)
 }
 
 // ---------------------------------------------------------------------------
@@ -535,38 +817,6 @@ private fun CategoryIcon(icon: ImageVector, accent: ChipAccent) {
     }
 }
 
-/** OptionCard selection dialog — the app's only sanctioned picker style. */
-@Composable
-private fun <T> OptionPickerDialog(
-    title: String,
-    options: List<T>,
-    selected: T,
-    label: @Composable (T) -> String,
-    onSelect: (T) -> Unit,
-    onDismiss: () -> Unit,
-) {
-    AlertDialog(
-        onDismissRequest = onDismiss,
-        title = { Text(title) },
-        text = {
-            Column(verticalArrangement = Arrangement.spacedBy(8.dp)) {
-                options.forEach { option ->
-                    OptionCard(
-                        label = label(option),
-                        onClick = {
-                            onSelect(option)
-                            onDismiss()
-                        },
-                        selected = option == selected,
-                    )
-                }
-            }
-        },
-        confirmButton = {
-            TextButton(onClick = onDismiss) { Text(stringResource(R.string.dialog_cancel)) }
-        },
-    )
-}
 
 private fun openUrl(context: Context, url: String) {
     val intent = Intent(Intent.ACTION_VIEW, url.toUri())

app/src/main/java/de/jeanlucmakiola/calendula/ui/settings/SettingsUiState.kt

@@ -3,6 +3,7 @@ package de.jeanlucmakiola.calendula.ui.settings
 import de.jeanlucmakiola.calendula.data.prefs.SettingsPrefs
 import de.jeanlucmakiola.calendula.data.prefs.ThemeMode
 import de.jeanlucmakiola.calendula.data.prefs.WeekStartPref
+import de.jeanlucmakiola.calendula.domain.CalendarSource
 import de.jeanlucmakiola.calendula.domain.EventFormField
 
 /**
@@ -20,6 +21,25 @@ data class SettingsUiState(
     val defaultFormFields: Set<EventFormField> = SettingsPrefs.DEFAULT_FORM_FIELDS,
     /** Whether Calendula posts reminder notifications (v1.4). */
     val remindersEnabled: Boolean = true,
+    /**
+     * The default reminder lead time (minutes) prefilled on new timed events;
+     * null = no default reminder. Per-calendar overrides take precedence.
+     */
+    val defaultReminderMinutes: Int? = null,
+    /** The default reminder lead time prefilled on new all-day events; null = none. */
+    val defaultAllDayReminderMinutes: Int? = null,
+    /** Wall-clock time (minutes from midnight) all-day reminders fire at; default 09:00. */
+    val allDayReminderTimeMinutes: Int = SettingsPrefs.DEFAULT_ALLDAY_REMINDER_TIME,
+    /**
+     * Per-calendar overrides of [defaultReminderMinutes] for timed events: a
+     * calendar present in the map overrides the global default (null value = no
+     * reminder); absent = inherit the global default.
+     */
+    val perCalendarReminderOverride: Map<Long, Int?> = emptyMap(),
+    /** Per-calendar overrides of [defaultAllDayReminderMinutes] for all-day events. */
+    val perCalendarAllDayReminderOverride: Map<Long, Int?> = emptyMap(),
+    /** Writable calendars, shown as per-calendar reminder-override rows. */
+    val writableCalendars: List<CalendarSource> = emptyList(),
     /**
      * Whether the event-colour picker is offered on calendars that publish no
      * colour palette (the colour may then not survive their next sync).

app/src/main/java/de/jeanlucmakiola/calendula/ui/settings/SettingsViewModel.kt

@@ -4,13 +4,19 @@ import android.os.Build
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
 import dagger.hilt.android.lifecycle.HiltViewModel
+import de.jeanlucmakiola.calendula.data.calendar.CalendarRepository
+import de.jeanlucmakiola.calendula.data.prefs.CalendarReminderOverride
 import de.jeanlucmakiola.calendula.data.prefs.SettingsPrefs
 import de.jeanlucmakiola.calendula.data.prefs.ThemeMode
 import de.jeanlucmakiola.calendula.data.prefs.WeekStartPref
+import de.jeanlucmakiola.calendula.domain.CalendarSource
 import de.jeanlucmakiola.calendula.domain.EventFormField
+import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.SharingStarted
 import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.catch
 import kotlinx.coroutines.flow.combine
+import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.flow.stateIn
 import kotlinx.coroutines.launch
 import javax.inject.Inject
@@ -18,14 +24,20 @@ import javax.inject.Inject
 @HiltViewModel
 class SettingsViewModel @Inject constructor(
     private val prefs: SettingsPrefs,
+    repository: CalendarRepository,
 ) : ViewModel() {
 
     private val dynamicColorAvailable = Build.VERSION.SDK_INT >= Build.VERSION_CODES.S
 
+    /** Writable calendars — the only ones that take a per-calendar reminder override. */
+    private val writableCalendars: Flow<List<CalendarSource>> = repository.calendars()
+        .map { calendars -> calendars.filter { it.canModifyContents } }
+        .catch { emit(emptyList()) }
+
     val state: StateFlow<SettingsUiState> =
         combine(
-            // combine() only types up to five flows, so the sixth pref folds
-            // into the assembled state in an outer combine.
+            // combine() types up to five flows, so the prefs split into two
+            // groups that fold together in the outer combine.
             combine(
                 prefs.themeMode,
                 prefs.dynamicColor,
@@ -42,15 +54,50 @@ class SettingsViewModel @Inject constructor(
                     remindersEnabled = reminders,
                 )
             },
-            prefs.allowColorOnUnsupportedCalendars,
-        ) { base, allowColor ->
-            base.copy(allowColorOnUnsupportedCalendars = allowColor)
+            combine(
+                prefs.allowColorOnUnsupportedCalendars,
+                prefs.defaultReminderMinutes,
+                prefs.defaultAllDayReminderMinutes,
+                prefs.allDayReminderTimeMinutes,
+            ) { allowColor, defaultReminder, allDayReminder, allDayReminderTime ->
+                ReminderDefaults(allowColor, defaultReminder, allDayReminder, allDayReminderTime)
+            },
+            combine(
+                prefs.perCalendarReminderOverride,
+                prefs.perCalendarAllDayReminderOverride,
+                writableCalendars,
+            ) { overrides, allDayOverrides, calendars ->
+                ReminderOverrides(overrides, allDayOverrides, calendars)
+            },
+        ) { base, defaults, overrides ->
+            base.copy(
+                allowColorOnUnsupportedCalendars = defaults.allowColor,
+                defaultReminderMinutes = defaults.defaultReminder,
+                defaultAllDayReminderMinutes = defaults.allDayReminder,
+                allDayReminderTimeMinutes = defaults.allDayReminderTime,
+                perCalendarReminderOverride = overrides.timed,
+                perCalendarAllDayReminderOverride = overrides.allDay,
+                writableCalendars = overrides.calendars,
+            )
         }.stateIn(
             scope = viewModelScope,
             started = SharingStarted.WhileSubscribed(5_000L),
             initialValue = SettingsUiState(dynamicColorAvailable = dynamicColorAvailable),
         )
 
+    private data class ReminderDefaults(
+        val allowColor: Boolean,
+        val defaultReminder: Int?,
+        val allDayReminder: Int?,
+        val allDayReminderTime: Int,
+    )
+
+    private data class ReminderOverrides(
+        val timed: Map<Long, Int?>,
+        val allDay: Map<Long, Int?>,
+        val calendars: List<CalendarSource>,
+    )
+
     fun setThemeMode(mode: ThemeMode) {
         viewModelScope.launch { prefs.setThemeMode(mode) }
     }
@@ -71,6 +118,26 @@ class SettingsViewModel @Inject constructor(
         viewModelScope.launch { prefs.setRemindersEnabled(enabled) }
     }
 
+    fun setDefaultReminderMinutes(minutes: Int?) {
+        viewModelScope.launch { prefs.setDefaultReminderMinutes(minutes) }
+    }
+
+    fun setDefaultAllDayReminderMinutes(minutes: Int?) {
+        viewModelScope.launch { prefs.setDefaultAllDayReminderMinutes(minutes) }
+    }
+
+    fun setAllDayReminderTimeMinutes(minutesOfDay: Int) {
+        viewModelScope.launch { prefs.setAllDayReminderTimeMinutes(minutesOfDay) }
+    }
+
+    fun setCalendarReminderOverride(calendarId: Long, override: CalendarReminderOverride) {
+        viewModelScope.launch { prefs.setCalendarReminderOverride(calendarId, override) }
+    }
+
+    fun setCalendarAllDayReminderOverride(calendarId: Long, override: CalendarReminderOverride) {
+        viewModelScope.launch { prefs.setCalendarAllDayReminderOverride(calendarId, override) }
+    }
+
     fun setAllowColorOnUnsupportedCalendars(enabled: Boolean) {
         viewModelScope.launch { prefs.setAllowColorOnUnsupportedCalendars(enabled) }
     }

app/src/main/res/values-de/strings.xml

@@ -248,6 +248,20 @@
     <string name="settings_section_notifications">Benachrichtigungen</string>
     <string name="settings_reminders">Termin-Erinnerungen</string>
     <string name="settings_reminders_hint">Erinnerungen doppelt? Eine andere Kalender-App zeigt sie ebenfalls — schalte sie in einer der beiden ab.</string>
+    <string name="settings_default_reminder">Standard-Erinnerung</string>
+    <string name="settings_default_reminder_allday">Ganztägige Termine</string>
+    <string name="settings_allday_reminder_time">Uhrzeit für ganztägige Erinnerungen</string>
+    <string name="settings_allday_reminder_time_hint">Erinnerungen für ganztägige Termine werden um %1$s ausgelöst</string>
+    <string name="reminder_none">Keine</string>
+    <string name="reminder_use_default">Standard-Erinnerung verwenden</string>
+    <string name="reminder_custom_amount">Anzahl</string>
+    <string name="reminder_custom_with_value">Benutzerdefiniert (%1$s)</string>
+    <string name="reminder_custom_set">Übernehmen</string>
+    <string name="settings_calendar_reminders_hint">Standard pro Kalender überschreiben — getrennt für Termine mit Uhrzeit und ganztägige Termine. Ein Kalender kann den Standard übernehmen, weglassen oder einen eigenen festlegen.</string>
+    <string name="settings_calendar_reminder_inherits">Standard (%1$s)</string>
+    <string name="settings_reliable_delivery">Zuverlässige Zustellung</string>
+    <string name="settings_reliable_delivery_hint">Android verzögert Erinnerungen womöglich, um Akku zu sparen. Nimm Calendula aus, damit sie pünktlich ankommen.</string>
+    <string name="settings_reliable_delivery_exempt">Von der Akku-Optimierung ausgenommen — Erinnerungen kommen pünktlich.</string>
     <string name="settings_section_calendars">Kalender</string>
     <string name="settings_manage_calendars">Kalender verwalten</string>
     <string name="settings_manage_calendars_hint">Lokale Kalender anlegen, synchronisierte verwalten</string>

app/src/main/res/values/strings.xml

@@ -245,6 +245,20 @@
     <string name="settings_section_notifications">Notifications</string>
     <string name="settings_reminders">Event reminders</string>
     <string name="settings_reminders_hint">Seeing reminders twice? Another calendar app is posting them too — turn them off in one of the two.</string>
+    <string name="settings_default_reminder">Default reminder</string>
+    <string name="settings_default_reminder_allday">All-day events</string>
+    <string name="settings_allday_reminder_time">All-day reminder time</string>
+    <string name="settings_allday_reminder_time_hint">Reminders for all-day events fire at %1$s</string>
+    <string name="reminder_none">None</string>
+    <string name="reminder_use_default">Use default reminder</string>
+    <string name="reminder_custom_amount">Amount</string>
+    <string name="reminder_custom_with_value">Custom (%1$s)</string>
+    <string name="reminder_custom_set">Set</string>
+    <string name="settings_calendar_reminders_hint">Override the default per calendar — separately for timed and all-day events. A calendar can keep the default, drop it, or set its own.</string>
+    <string name="settings_calendar_reminder_inherits">Default (%1$s)</string>
+    <string name="settings_reliable_delivery">Reliable delivery</string>
+    <string name="settings_reliable_delivery_hint">Android may delay reminders to save battery. Exempt Calendula so they arrive on time.</string>
+    <string name="settings_reliable_delivery_exempt">Exempt from battery optimisation — reminders arrive on time.</string>
     <string name="settings_section_calendars">Calendars</string>
     <string name="settings_manage_calendars">Manage calendars</string>
     <string name="settings_manage_calendars_hint">Create local calendars; manage synced ones</string>