fix(#518): review round 4 — silent channels read as silent, honest pick results, clearer failures

The day view's top bar now shows the month name (e.g. "November", abbreviated when space is short, with the year outside the current year), the same as the week and 3-day views. Weekday and date already sit in the column header right below, so the old title repeated them.

Closes #501

Co-authored-by: Jean-Luc Makiola <business@jeanlucmakiola.de>
Reviewed-on: https://codeberg.org/jlmakiola/calendula/pulls/505

.gitea/workflows/renovate.yml

@@ -33,7 +33,7 @@ jobs:
     # directly drops the docker-in-docker requirement entirely.
     # Full tag pinned; Renovate's github-actions manager keeps it bumped.
     container:
-      image: ghcr.io/renovatebot/renovate:43.232.0
+      image: ghcr.io/renovatebot/renovate:44.237.3
     steps:
       - name: Run Renovate
         run: renovate

CHANGELOG.md

@@ -7,6 +7,16 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [2.24.2] — 2026-11-13
+
+### Fixed
+- **Quick moves no longer get lost.** Dropping an event while an earlier move was still saving used to snap it back without a word. Drops now wait in line and are saved in order, and a moved event stays where you dropped it until the calendar shows it there. If an event changed before a drop could be saved, or the line is full, a message says so instead ([#494]).
+- **Undo after a run of moves** keeps the first move's Undo, and each failed move gets its own message rather than replacing the last one ([#494]).
+
+### Changed
+- **The day view's title names the month**, like the week and 3-day views. Weekday and date already sit in the column header below it ([#501]).
+- Library updates (kotlinx-datetime, AppCompat).
+
 ## [2.24.1] — 2026-11-12
 
 ### Added
@@ -1973,3 +1983,5 @@ automatically, with zero telemetry and no internet permission.
 [#489]: https://codeberg.org/jlmakiola/calendula/issues/489
 [#491]: https://codeberg.org/jlmakiola/calendula/issues/491
 [#493]: https://codeberg.org/jlmakiola/calendula/issues/493
+[#494]: https://codeberg.org/jlmakiola/calendula/issues/494
+[#501]: https://codeberg.org/jlmakiola/calendula/issues/501

Gemfile

@@ -7,4 +7,4 @@ source "https://rubygems.org"
 # Pinned exactly; Renovate's bundler manager keeps it bumped. No Gemfile.lock is
 # committed on purpose: this resolves an uploader's transitive deps, not the
 # app's, and none of it affects the reproducible release build.
-gem "fastlane", "2.237.0"
+gem "fastlane", "2.241.1"

app/build.gradle.kts

@@ -32,8 +32,8 @@ android {
         // (up to 2.22.3: 2.22.3 -> 22203; from 2.22.4: 2.23.0-beta.1 -> 2230001,
         // 2.22.4 -> 2220499), and CI fails if the committed one doesn't match.
         // See docs/RELEASING.md.
-        versionCode = 2240199
-        versionName = "2.24.1"
+        versionCode = 2240299
+        versionName = "2.24.2"
 
         testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
     }

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

@@ -81,7 +81,7 @@ class CalendarPrefs @Inject constructor(
 }
 
 /** A comma-joined id set; non-numeric tokens are dropped, and an empty set removes the key. */
-private fun idSetPref(name: String): Pref<Set<Long>> = nullableStringPref(name).map(
+internal fun idSetPref(name: String): Pref<Set<Long>> = nullableStringPref(name).map(
     { stored -> stored.orEmpty().split(',').mapNotNull { it.trim().toLongOrNull() }.toSet() },
     { ids -> if (ids.isEmpty()) null else ids.sorted().joinToString(",") },
 )

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

@@ -166,6 +166,9 @@ class SettingsPrefs @Inject constructor(
     val defaultEventDurationMinutes: Flow<Int> = prefs.flow(SettingsKeys.defaultEventDurationMinutes)
     val perCalendarEventDuration: Flow<Map<Long, Int>> = prefs.flow(SettingsKeys.perCalendarEventDuration)
     val remindersEnabled: Flow<Boolean> = prefs.flow(SettingsKeys.remindersEnabled)
+    val mutedReminderCalendarIds: Flow<Set<Long>> = prefs.flow(SettingsKeys.mutedReminderCalendarIds)
+    val notificationCategoryHintDismissed: Flow<Boolean> = prefs.flow(SettingsKeys.notificationCategoryHintDismissed)
+    val reminderChannelVersions: Flow<Map<Long, Int>> = prefs.flow(SettingsKeys.reminderChannelVersions)
     val allowColorOnUnsupportedCalendars: Flow<Boolean> =
         prefs.flow(SettingsKeys.allowColorOnUnsupportedCalendars)
     val defaultReminderMinutes: Flow<List<Int>> = prefs.flow(SettingsKeys.defaultReminderMinutes)
@@ -273,6 +276,25 @@ class SettingsPrefs @Inject constructor(
 
     suspend fun setRemindersEnabled(enabled: Boolean) = prefs.set(SettingsKeys.remindersEnabled, enabled)
 
+    /**
+     * Reserve a new reminder channel version for each calendar in [floors], above
+     * both its stored high-water mark and its floor, and return them. Versions
+     * only grow: the system would restore a deleted channel's old settings if
+     * its id came back (#518).
+     */
+    suspend fun reserveReminderChannelVersions(floors: Map<Long, Int>): Map<Long, Int> {
+        val stored = prefs.update(SettingsKeys.reminderChannelVersions) { current ->
+            current + floors.mapValues { (id, floor) -> maxOf((current[id] ?: 0) + 1, floor) }
+        }
+        return floors.keys.associateWith { stored.getValue(it) }
+    }
+
+    suspend fun dismissNotificationCategoryHint() = prefs.set(SettingsKeys.notificationCategoryHintDismissed, true)
+
+    suspend fun setCalendarRemindersEnabled(calendarId: Long, enabled: Boolean) {
+        prefs.update(SettingsKeys.mutedReminderCalendarIds) { if (enabled) it - calendarId else it + calendarId }
+    }
+
     suspend fun setAllowColorOnUnsupportedCalendars(enabled: Boolean) =
         prefs.set(SettingsKeys.allowColorOnUnsupportedCalendars, enabled)
 
@@ -594,6 +616,27 @@ object SettingsKeys {
      */
     val remindersEnabled: Pref<Boolean> = booleanPref("reminders_enabled", true)
 
+    /**
+     * Calendars whose reminders Calendula doesn't post (#272), independent of
+     * `Calendars.VISIBLE`: the events still show, only the notifications stop.
+     */
+    val mutedReminderCalendarIds: Pref<Set<Long>> = idSetPref("muted_reminder_calendar_ids")
+
+    /**
+     * Whether the one-time hint that some skins (Samsung) start new notification
+     * categories switched off has been dismissed (#145).
+     */
+    val notificationCategoryHintDismissed: Pref<Boolean> = booleanPref("notification_category_hint_dismissed", false)
+
+    /**
+     * The highest reminder channel version handed out per calendar (#518): a
+     * sound picked in the app recreates the channel under a new one. The
+     * channels themselves say which version is current; this only keeps ids
+     * from being reused. Serialised as `id=version;id=version`.
+     */
+    val reminderChannelVersions: Pref<Map<Long, Int>> =
+        nullableStringPref("reminder_channel_versions").map(::parseChannelVersions) { it.toStoredVersions() }
+
     /**
      * Whether to offer a custom event colour on calendars that publish no colour
      * palette; synced ones without a palette (some CalDAV) may drop or overwrite
@@ -977,6 +1020,18 @@ private fun parseDurationOverrides(stored: String?): Map<Long, Int> =
         calendarId to minutes
     }.toMap()
 
+private fun parseChannelVersions(stored: String?): Map<Long, Int> =
+    stored?.split(ENTRY_SEP).orEmpty().mapNotNull { entry ->
+        val parts = entry.split(KEY_VALUE_SEP)
+        if (parts.size != 2) return@mapNotNull null
+        val calendarId = parts[0].trim().toLongOrNull() ?: return@mapNotNull null
+        val version = parts[1].trim().toIntOrNull()?.takeIf { it > 0 } ?: return@mapNotNull null
+        calendarId to version
+    }.toMap()
+
+private fun Map<Long, Int>.toStoredVersions(): String? =
+    if (isEmpty()) null else entries.sortedBy { it.key }.joinToString(ENTRY_SEP) { (id, v) -> "$id$KEY_VALUE_SEP$v" }
+
 private fun Map<Long, Int>.toStoredDurations(): String =
     entries.sortedBy { it.key }.joinToString(ENTRY_SEP) { (id, minutes) ->
         "$id$KEY_VALUE_SEP$minutes"

app/src/main/java/de/jeanlucmakiola/calendula/data/reminders/ReminderChannelPlan.kt

@@ -0,0 +1,201 @@
+package de.jeanlucmakiola.calendula.data.reminders
+
+import de.jeanlucmakiola.calendula.domain.CalendarSource
+import de.jeanlucmakiola.calendula.ui.common.groupByAccount
+
+/** The single channel every reminder posted on before they moved per calendar (#145). */
+const val LEGACY_REMINDER_CHANNEL_ID = "reminders"
+
+private const val CHANNEL_PREFIX = "reminders.calendar."
+private const val GROUP_PREFIX = "reminders.account."
+private const val LOCAL_GROUP_ID = GROUP_PREFIX + "local"
+
+private const val VERSION_SEPARATOR = ".v"
+
+/**
+ * The notification channel [calendarId]'s reminders post on. A sound picked in
+ * the app moves it to a new [version] (#518), since a channel's sound is fixed
+ * once created; version 0 is the unversioned id #145 introduced.
+ */
+fun reminderChannelId(calendarId: Long, version: Int = 0): String =
+    if (version == 0) "$CHANNEL_PREFIX$calendarId" else "$CHANNEL_PREFIX$calendarId$VERSION_SEPARATOR$version"
+
+/** The calendar and version a reminder channel id names, or null for any other id. */
+fun parseReminderChannelId(channelId: String): Pair<Long, Int>? {
+    if (!isReminderChannelId(channelId)) return null
+    val rest = channelId.removePrefix(CHANNEL_PREFIX)
+    val calendar = rest.substringBefore(VERSION_SEPARATOR).toLongOrNull() ?: return null
+    if (VERSION_SEPARATOR !in rest) return calendar to 0
+    val version = rest.substringAfter(VERSION_SEPARATOR).toIntOrNull()?.takeIf { it > 0 } ?: return null
+    return calendar to version
+}
+
+/**
+ * Each calendar's current channel version: the highest one that exists, so a
+ * new version only takes over once it is written. A calendar with none falls
+ * back to its [highWater] mark — re-creating that id restores its own settings.
+ */
+fun currentReminderChannelVersions(existingChannelIds: Collection<String>, highWater: Map<Long, Int>): Map<Long, Int> {
+    val existing = existingChannelIds.mapNotNull(::parseReminderChannelId)
+        .groupBy({ it.first }, { it.second })
+        .mapValues { (_, versions) -> versions.max() }
+    return highWater + existing
+}
+
+/** Whether [channelId] is one of the per-calendar reminder channels. */
+fun isReminderChannelId(channelId: String): Boolean = channelId.startsWith(CHANNEL_PREFIX)
+
+/** Whether [groupId] is one of the per-account reminder channel groups. */
+fun isReminderGroupId(groupId: String): Boolean = groupId.startsWith(GROUP_PREFIX)
+
+/**
+ * One account's channel group, labelled as the calendar manager labels it. The
+ * app's own device calendars share a single group ([isLocal]); [ambiguous]
+ * marks a [label] another group shows too, so it should name the source app.
+ */
+data class ReminderChannelGroupSpec(
+    val id: String,
+    val label: String,
+    val accountType: String,
+    val isLocal: Boolean,
+    val ambiguous: Boolean,
+)
+
+data class ReminderChannelSpec(
+    val id: String,
+    val calendarId: Long,
+    val name: String,
+    /** Null only for a channel created before its calendar could be looked up. */
+    val groupId: String?,
+    /**
+     * Whether a sync creates it up front. A calendar that syncs no events never
+     * fires, so its channel only appears once something posts on it.
+     */
+    val upFront: Boolean = true,
+)
+
+/** What a channel already looks like in the system, as far as the plan compares it. */
+data class ExistingReminderChannel(val id: String, val name: String, val description: String?, val groupId: String?)
+
+data class ReminderChannelPlan(
+    val groups: List<ReminderChannelGroupSpec>,
+    val channels: List<ReminderChannelSpec>,
+    /**
+     * The [channels] a sync writes: missing up-front ones, and existing ones
+     * whose name or (localized) description changed, or that still lack a group.
+     */
+    val channelsToWrite: List<ReminderChannelSpec>,
+    /** The [groups] holding a channel that exists or is about to be written. */
+    val groupsInUse: List<ReminderChannelGroupSpec>,
+    val staleChannelIds: List<String>,
+    val staleGroupIds: List<String>,
+    /** Stale channels kept for now, because a notification on them is still showing. */
+    val keptChannelIds: List<String> = emptyList(),
+)
+
+/**
+ * What the reminder channels should look like for [calendars]: one channel per
+ * calendar inside a group per account, which of them need writing, and the
+ * reminder channels and groups in [existing] / [existingGroupIds] no calendar
+ * claims any more. Ids outside the reminder namespace (the backup channel, the
+ * legacy channel) are never touched.
+ */
+fun planReminderChannels(
+    calendars: List<CalendarSource>,
+    existing: Collection<ExistingReminderChannel>,
+    existingGroupIds: Collection<String>,
+    unnamed: String,
+    description: String,
+    versions: Map<Long, Int> = emptyMap(),
+    showingChannelIds: Set<String> = emptySet(),
+): ReminderChannelPlan {
+    val (local, synced) = calendars.partition { it.isLocal }
+    val groups = buildList {
+        if (local.isNotEmpty()) {
+            add(ReminderChannelGroupSpec(LOCAL_GROUP_ID, "", local.first().accountType, isLocal = true, ambiguous = false))
+        }
+        synced.groupByAccount().forEach { group ->
+            add(
+                ReminderChannelGroupSpec(
+                    id = accountGroupId(group.key.type, group.key.name),
+                    label = group.label,
+                    accountType = group.accountType,
+                    isLocal = false,
+                    ambiguous = group.ambiguous,
+                ),
+            )
+        }
+    }
+    val existingById = existing.associateBy { it.id }
+    val channels = calendars.map { calendar ->
+        ReminderChannelSpec(
+            id = reminderChannelId(calendar.id, versions[calendar.id] ?: 0),
+            calendarId = calendar.id,
+            name = calendar.displayName.ifBlank { unnamed },
+            groupId = if (calendar.isLocal) LOCAL_GROUP_ID else accountGroupId(calendar.accountType, calendar.accountName),
+            upFront = calendar.isLocal || calendar.syncsEvents,
+        )
+    }
+    val wantedChannels = channels.mapTo(HashSet()) { it.id }
+    val wantedGroups = groups.mapTo(HashSet()) { it.id }
+    val toWrite = channels.filter { spec ->
+        val current = existingById[spec.id]
+        if (current == null) {
+            spec.upFront
+        } else {
+            current.name != spec.name || current.description != description ||
+                (current.groupId == null && spec.groupId != null)
+        }
+    }
+    val usedGroupIds = channels
+        .filter { it.id in existingById || it in toWrite }
+        .mapNotNullTo(HashSet()) { it.groupId }
+    val (kept, stale) = existingById.keys
+        .filter { isReminderChannelId(it) && it !in wantedChannels }
+        .partition { it in showingChannelIds }
+    val keptGroups = kept.mapNotNullTo(HashSet()) { existingById.getValue(it).groupId }
+    return ReminderChannelPlan(
+        groups = groups,
+        channels = channels,
+        channelsToWrite = toWrite,
+        groupsInUse = groups.filter { it.id in usedGroupIds },
+        staleChannelIds = stale,
+        staleGroupIds = existingGroupIds.filter { isReminderGroupId(it) && it !in wantedGroups && it !in keptGroups },
+        keptChannelIds = kept,
+    )
+}
+
+private fun accountGroupId(type: String, name: String): String = "$GROUP_PREFIX$type/$name"
+
+/** A channel as far as its blocked state goes: switched off itself, and the group it sits in. */
+data class ReminderChannelState(val blocked: Boolean, val groupId: String?)
+
+/** Reminder notifications the system blocks, while Calendula would post them. */
+data class ReminderChannelStatus(
+    val appBlocked: Boolean = false,
+    val blockedCalendarIds: Set<Long> = emptySet(),
+    /** The blocked ones whose whole account group is off, which only the app's own screen can undo. */
+    val groupBlockedCalendarIds: Set<Long> = emptySet(),
+)
+
+/**
+ * What the system blocks of [calendarIds]' reminders: all of them while the
+ * app's notifications are off, otherwise those whose channel, or the group it
+ * sits in, is switched off. A calendar without a channel yet isn't blocked.
+ */
+fun reminderChannelStatus(
+    calendarIds: Collection<Long>,
+    appEnabled: Boolean,
+    channels: Map<String, ReminderChannelState>,
+    blockedGroupIds: Set<String>,
+    versions: Map<Long, Int> = emptyMap(),
+): ReminderChannelStatus {
+    fun channel(calendarId: Long) = channels[reminderChannelId(calendarId, versions[calendarId] ?: 0)]
+    val groupBlocked = calendarIds.filterTo(HashSet()) { channel(it)?.groupId in blockedGroupIds }
+    val blocked = if (!appEnabled) {
+        calendarIds.toSet()
+    } else {
+        calendarIds.filterTo(HashSet()) { channel(it)?.blocked == true } + groupBlocked
+    }
+    return ReminderChannelStatus(appBlocked = !appEnabled, blockedCalendarIds = blocked, groupBlockedCalendarIds = groupBlocked)
+}

app/src/main/java/de/jeanlucmakiola/calendula/data/reminders/ReminderChannels.kt

@@ -0,0 +1,353 @@
+package de.jeanlucmakiola.calendula.data.reminders
+
+import android.app.Notification
+import android.app.NotificationChannel
+import android.app.NotificationChannelGroup
+import android.app.NotificationManager
+import android.app.NotificationManager.IMPORTANCE_DEFAULT
+import android.app.NotificationManager.IMPORTANCE_LOW
+import android.app.NotificationManager.IMPORTANCE_MIN
+import android.content.Context
+import android.media.AudioAttributes
+import android.net.Uri
+import android.util.Log
+import dagger.hilt.android.qualifiers.ApplicationContext
+import de.jeanlucmakiola.calendula.R
+import de.jeanlucmakiola.calendula.data.calendar.CalendarDataSource
+import de.jeanlucmakiola.calendula.data.prefs.SettingsPrefs
+import de.jeanlucmakiola.calendula.domain.CalendarSource
+import de.jeanlucmakiola.calendula.ui.common.sourceAppLabel
+import kotlinx.coroutines.flow.first
+import kotlinx.coroutines.runBlocking
+import java.util.Locale
+import javax.inject.Inject
+import javax.inject.Singleton
+
+/**
+ * The reminder notification channels: one per calendar, grouped by account
+ * (#145), created up front so each calendar can be muted or given its own sound
+ * in the system settings before it ever fires.
+ *
+ * A channel the user has touched keeps their settings; [sync] only creates the
+ * missing ones, renames changed ones, and deletes those whose calendar is gone.
+ * A sound picked in the app ([setSound], #518) recreates the channel under the
+ * calendar's next version; the old one goes once nothing shows on it.
+ */
+@Singleton
+class ReminderChannels @Inject constructor(
+    @ApplicationContext private val context: Context,
+    private val calendarDataSource: CalendarDataSource,
+    private val settingsPrefs: SettingsPrefs,
+) {
+    private val manager: NotificationManager
+        get() = context.getSystemService(NotificationManager::class.java)
+
+    /** What the last [sync] saw, so an unchanged provider costs no channel writes. */
+    @Volatile
+    private var lastSync: Any? = null
+
+    /**
+     * Bring the channels in line with the provider's calendars. An empty
+     * snapshot changes nothing: that is a provider hiccup far more often than
+     * every calendar gone at once.
+     */
+    @Synchronized
+    fun sync() {
+        val calendars = calendarDataSource.calendars()
+        if (calendars.isEmpty()) return
+        val manager = manager
+        val existing = manager.notificationChannels
+        val existingIds = existing.mapTo(HashSet()) { it.id }
+        val versions = currentVersions(existingIds).also { knownVersions = it }
+        if (syncKey(calendars, existingIds, versions) == lastSync && LEGACY_REMINDER_CHANNEL_ID !in existingIds) return
+        val groups = manager.notificationChannelGroups
+        val groupIds = groups.map { it.id }
+        // Active notifications are only read when there is something stale to protect.
+        val plan = plan(calendars, existing, groupIds, versions).let { draft ->
+            if (draft.staleChannelIds.isEmpty()) draft else plan(calendars, existing, groupIds, versions, showingChannelIds(draft.staleChannelIds))
+        }
+        plan.staleChannelIds.forEach(manager::deleteNotificationChannel)
+        plan.staleGroupIds.forEach(manager::deleteNotificationChannelGroup)
+        val groupNames = groups.associate { it.id to it.name?.toString() }
+        write(
+            groups = plan.groupsInUse.filter { groupNames[it.id] != groupLabel(it) },
+            channels = plan.channelsToWrite,
+            existing = existing,
+        )
+        val ids = existingIds - plan.staleChannelIds.toSet() + plan.channelsToWrite.map { it.id }
+        val legacyGone = retireLegacyChannel()
+        // A kept channel still has to go once its notification does, so don't cache.
+        lastSync = if (plan.keptChannelIds.isEmpty()) {
+            syncKey(calendars, if (legacyGone) ids - LEGACY_REMINDER_CHANNEL_ID else ids, versions)
+        } else {
+            null
+        }
+    }
+
+    private fun syncKey(calendars: List<CalendarSource>, channelIds: Set<String>, versions: Map<Long, Int>): Any = listOf(
+        calendars.map { listOf(it.id, it.displayName, it.accountName, it.accountType, it.isLocal, it.syncsEvents) },
+        Locale.getDefault(),
+        channelIds,
+        versions,
+    )
+
+    /**
+     * The current versions last resolved under the lock ([sync], [channelFor]).
+     * Only [recreate], under the same lock, moves a calendar higher and updates
+     * it, so a hit whose channel still exists is current.
+     */
+    @Volatile
+    private var knownVersions: Map<Long, Int> = emptyMap()
+
+    private fun currentVersions(existingChannelIds: Collection<String>): Map<Long, Int> =
+        currentReminderChannelVersions(existingChannelIds, runBlocking { settingsPrefs.reminderChannelVersions.first() })
+
+    /** Channels with a notification on screen; on failure all of [candidates] count, so none is deleted. */
+    private fun showingChannelIds(candidates: Collection<String>): Set<String> = runCatching {
+        manager.activeNotifications.mapNotNullTo(HashSet()) { it.notification.channelId }
+    }.getOrElse { e ->
+        Log.w(TAG, "Could not read active notifications", e)
+        candidates.toSet()
+    }
+
+    /**
+     * The channel to post [calendarId]'s reminder on, created first if a sync
+     * has not got to it yet. Null when the calendar no longer exists. Should the
+     * calendar lookup fail or come back empty, the channel is still created,
+     * plainly named and ungrouped, for the next sync to name and file — a
+     * reminder is never lost to its channel.
+     */
+    @Synchronized
+    fun channelFor(calendarId: Long): String? {
+        val manager = manager
+        knownVersions[calendarId]?.let { version ->
+            val known = reminderChannelId(calendarId, version)
+            if (manager.getNotificationChannel(known) != null) return known
+        }
+        val existing = manager.notificationChannels
+        val versions = currentVersions(existing.map { it.id }).also { knownVersions = it }
+        val id = reminderChannelId(calendarId, versions[calendarId] ?: 0)
+        if (existing.any { it.id == id }) return id
+        val calendars = try {
+            calendarDataSource.calendars()
+        } catch (e: Exception) {
+            Log.w(TAG, "Could not look up calendar $calendarId for its channel", e)
+            emptyList()
+        }
+        val fallback = ReminderChannelSpec(id, calendarId, context.getString(R.string.reminder_channel_name), null)
+        if (calendars.isEmpty()) {
+            write(emptyList(), listOf(fallback), existing)
+            return id
+        }
+        val plan = plan(calendars, existing, emptyList(), versions)
+        val spec = plan.channels.firstOrNull { it.calendarId == calendarId } ?: return null
+        try {
+            val knownGroups = manager.notificationChannelGroups.mapTo(HashSet()) { it.id }
+            write(
+                groups = plan.groups.filter { it.id == spec.groupId && it.id !in knownGroups },
+                channels = listOf(spec),
+                existing = existing,
+            )
+        } catch (e: RuntimeException) {
+            Log.w(TAG, "Could not file the channel of calendar $calendarId", e)
+            write(emptyList(), listOf(fallback), existing)
+        }
+        return id
+    }
+
+    /**
+     * Run [block] with [calendarId]'s channel held: no sound pick or sync can
+     * move or retire it until [block] returns. Null, without running [block],
+     * when the calendar is gone or its channel can't be made; [block]'s own
+     * failures propagate.
+     */
+    @Synchronized
+    fun <T> withChannel(calendarId: Long, block: (String) -> T): T? {
+        val channelId = try {
+            channelFor(calendarId)
+        } catch (e: Exception) {
+            Log.w(TAG, "No channel for calendar $calendarId", e)
+            null
+        }
+        return channelId?.let(block)
+    }
+
+    /** What the system currently lets through for [calendarIds]' reminders (#145). */
+    fun status(calendarIds: Collection<Long>): ReminderChannelStatus {
+        val manager = manager
+        val appEnabled = manager.areNotificationsEnabled()
+        val existing = manager.notificationChannels
+        val channels = existing.associate {
+            it.id to ReminderChannelState(it.importance == NotificationManager.IMPORTANCE_NONE, it.group)
+        }
+        val blockedGroups = manager.notificationChannelGroups.filter { it.isBlocked }.mapTo(HashSet()) { it.id }
+        return reminderChannelStatus(calendarIds, appEnabled, channels, blockedGroups, currentVersions(channels.keys))
+    }
+
+    /** A "Silent" (low) channel keeps its sound but never plays it. */
+    private fun NotificationChannel.audibleSound(): Uri? =
+        sound.takeUnless { importance in IMPORTANCE_MIN..IMPORTANCE_LOW }
+
+    /**
+     * The sound each of [calendarIds]' channels plays; null is silent. A
+     * calendar whose channel doesn't exist yet is left out.
+     */
+    fun sounds(calendarIds: Collection<Long>): Map<Long, Uri?> {
+        val byId = manager.notificationChannels.associateBy { it.id }
+        val versions = currentVersions(byId.keys)
+        return calendarIds.mapNotNull { id ->
+            byId[reminderChannelId(id, versions[id] ?: 0)]?.let { id to it.audibleSound() }
+        }.toMap()
+    }
+
+    /**
+     * Give [calendarIds]' reminders [sound] (null = silent). A channel's sound is
+     * fixed once created, so each moves to a new channel version carrying over
+     * everything else, and the old one retires on the next sync (#518). Calendars without a
+     * channel are skipped unless [createMissing]. Returns whether every move
+     * went through.
+     */
+    suspend fun setSound(calendarIds: Collection<Long>, sound: Uri?, createMissing: Boolean): Boolean {
+        if (createMissing) calendarIds.forEach(::channelFor)
+        val existingIds = manager.notificationChannels.mapTo(HashSet()) { it.id }
+        val current = currentVersions(existingIds)
+        val floors = calendarIds
+            .filter { reminderChannelId(it, current[it] ?: 0) in existingIds }
+            .associateWith { (current[it] ?: 0) + 1 }
+        if (floors.isEmpty()) return false
+        return recreate(settingsPrefs.reserveReminderChannelVersions(floors), sound)
+    }
+
+    /**
+     * Create each calendar's [versions] from its current channel. The old one is
+     * left to the next [sync], which retires it once nothing shows on it.
+     */
+    @Synchronized
+    private fun recreate(versions: Map<Long, Int>, sound: Uri?): Boolean {
+        val manager = manager
+        val byId = manager.notificationChannels.associateBy { it.id }
+        val current = currentReminderChannelVersions(byId.keys, emptyMap())
+        var allApplied = true
+        versions.forEach { (calendarId, version) ->
+            val from = current[calendarId]?.takeIf { it < version }
+            val old = from?.let { byId[reminderChannelId(calendarId, it)] }
+            if (old == null) {
+                allApplied = false
+                return@forEach
+            }
+            try {
+                // Picking a sound asks for one, which a "Silent" (low) channel would never play.
+                val importance = if (sound != null && old.importance in IMPORTANCE_MIN..IMPORTANCE_LOW) {
+                    IMPORTANCE_DEFAULT
+                } else {
+                    old.importance
+                }
+                manager.createNotificationChannel(
+                    NotificationChannel(reminderChannelId(calendarId, version), old.name, importance).apply {
+                        description = old.description
+                        old.group?.let { group = it }
+                        inheritFrom(old)
+                        setSound(sound, old.audioAttributes ?: DEFAULT_AUDIO_ATTRIBUTES)
+                    },
+                )
+                knownVersions = knownVersions + (calendarId to version)
+            } catch (e: RuntimeException) {
+                Log.w(TAG, "Could not move calendar $calendarId to a new sound", e)
+                allApplied = false
+            }
+        }
+        lastSync = null
+        return allApplied
+    }
+
+    private fun plan(
+        calendars: List<CalendarSource>,
+        existing: List<NotificationChannel>,
+        existingGroupIds: List<String>,
+        versions: Map<Long, Int>,
+        showingChannelIds: Set<String> = emptySet(),
+    ): ReminderChannelPlan = planReminderChannels(
+        calendars = calendars,
+        existing = existing.map { ExistingReminderChannel(it.id, it.name.toString(), it.description, it.group) },
+        existingGroupIds = existingGroupIds,
+        unnamed = context.getString(R.string.calendar_unnamed),
+        description = context.getString(R.string.reminder_channel_description),
+        versions = versions,
+        showingChannelIds = showingChannelIds,
+    )
+
+    private fun write(
+        groups: List<ReminderChannelGroupSpec>,
+        channels: List<ReminderChannelSpec>,
+        existing: List<NotificationChannel>,
+    ) {
+        val manager = manager
+        if (groups.isNotEmpty()) {
+            manager.createNotificationChannelGroups(groups.map { NotificationChannelGroup(it.id, groupLabel(it)) })
+        }
+        if (channels.isEmpty()) return
+        val byId = existing.associateBy { it.id }
+        val description = context.getString(R.string.reminder_channel_description)
+        val template = byId[LEGACY_REMINDER_CHANNEL_ID]
+        // Importance only applies on creation; an existing channel keeps its own.
+        manager.createNotificationChannels(
+            channels.map { spec ->
+                val current = byId[spec.id]
+                NotificationChannel(
+                    spec.id,
+                    spec.name,
+                    current?.importance ?: template?.importance ?: NotificationManager.IMPORTANCE_HIGH,
+                ).apply {
+                    this.description = description
+                    spec.groupId?.let { group = it }
+                    if (current == null && template != null) inheritFrom(template)
+                }
+            },
+        )
+    }
+
+    /**
+     * Carry a channel's sound, vibration, lights and badge over to a new one: the
+     * legacy channel to a per-calendar one on upgrade, or a calendar's channel to
+     * its next version (#518). Lock-screen visibility and a DND override can't
+     * follow: the system resets both on channels an app creates.
+     */
+    private fun NotificationChannel.inheritFrom(template: NotificationChannel) {
+        setSound(template.sound, template.audioAttributes)
+        // The pattern setter also flips vibration on or off, so it goes first.
+        vibrationPattern = template.vibrationPattern
+        enableVibration(template.shouldVibrate())
+        enableLights(template.shouldShowLights())
+        lightColor = template.lightColor
+        setShowBadge(template.canShowBadge())
+        // Only honoured with Do Not Disturb access, so usually left to the user.
+        setBypassDnd(template.canBypassDnd())
+    }
+
+    /**
+     * Delete the pre-#145 channel once the per-calendar ones carry its settings,
+     * but not while a reminder posted on it is still on screen — deleting the
+     * channel would take that notification with it. Returns whether it is gone.
+     */
+    private fun retireLegacyChannel(): Boolean {
+        val manager = manager
+        if (manager.getNotificationChannel(LEGACY_REMINDER_CHANNEL_ID) == null) return true
+        val showing = LEGACY_REMINDER_CHANNEL_ID in showingChannelIds(listOf(LEGACY_REMINDER_CHANNEL_ID))
+        if (!showing) manager.deleteNotificationChannel(LEGACY_REMINDER_CHANNEL_ID)
+        return !showing
+    }
+
+    private fun groupLabel(group: ReminderChannelGroupSpec): String {
+        if (group.isLocal) return context.getString(R.string.calendars_local_header)
+        val name = group.label.ifBlank { context.getString(R.string.calendar_unnamed) }
+        if (!group.ambiguous) return name
+        return context.getString(R.string.calendars_account_from_source, name, sourceAppLabel(context, group.accountType))
+    }
+
+    private companion object {
+        const val TAG = "ReminderChannels"
+
+        val DEFAULT_AUDIO_ATTRIBUTES: AudioAttributes = Notification.AUDIO_ATTRIBUTES_DEFAULT
+    }
+}
+

app/src/main/java/de/jeanlucmakiola/calendula/data/reminders/ReminderNotifier.kt

@@ -1,8 +1,6 @@
 package de.jeanlucmakiola.calendula.data.reminders
 
 import android.Manifest
-import android.app.NotificationChannel
-import android.app.NotificationManager
 import android.app.PendingIntent
 import android.content.Context
 import android.os.Build
@@ -29,8 +27,8 @@ import javax.inject.Inject
 import javax.inject.Singleton
 
 /**
- * Posts one notification per occurrence on a dedicated channel. Tapping opens
- * the event's detail screen.
+ * Posts one notification per occurrence on its calendar's channel
+ * ([ReminderChannels], #145). Tapping opens the event's detail screen.
  *
  * The tag is the [occurrenceKey], so each reminder for an occurrence replaces
  * the one before it in place (#463). A different reminder alerts afresh; the
@@ -43,6 +41,7 @@ class ReminderNotifier @Inject constructor(
     private val settingsPrefs: SettingsPrefs,
     private val calendarPrefs: CalendarPrefs,
     private val calendarDataSource: CalendarDataSource,
+    private val channels: ReminderChannels,
 ) {
 
     /** False when the user declined `POST_NOTIFICATIONS` or muted the app. */
@@ -53,19 +52,19 @@ class ReminderNotifier @Inject constructor(
     }
 
     /**
-     * The single choke point for "this calendar is switched off", covering the
-     * two paths that reach [post] around the scan's own filter: a snooze armed
-     * before the switch-off, and a read-only install whose switch lives in
-     * [CalendarPrefs].
+     * The single choke point for "this calendar posts no reminders": switched
+     * off (also covering a snooze armed before the switch-off, and a read-only
+     * install whose switch lives in [CalendarPrefs]), or its notifications
+     * turned off in Calendula's own settings (#272).
      */
     private suspend fun isSilenced(calendarId: Long): Boolean =
-        calendarId in calendarPrefs.pendingDisabledCalendarIds.first() ||
+        calendarId in settingsPrefs.mutedReminderCalendarIds.first() ||
+            calendarId in calendarPrefs.pendingDisabledCalendarIds.first() ||
             calendarDataSource.isCalendarVisible(calendarId) == false
 
-    /** Post [alert], unless its calendar is switched off. */
+    /** Post [alert], unless its calendar is silenced or gone. */
     suspend fun post(alert: ReminderAlert) {
         if (isSilenced(alert.calendarId)) return
-        ensureChannel()
         val title = displayTitle(alert)
         val is24Hour = settingsPrefs.timeFormat.first()
             .is24Hour(android.text.format.DateFormat.is24HourFormat(context))
@@ -88,7 +87,15 @@ class ReminderNotifier @Inject constructor(
             yesterdayLabel = context.getString(R.string.reminder_day_yesterday),
         )
         val text = listOfNotNull(time, alert.location).joinToString(" · ")
-        val notification = NotificationCompat.Builder(context, CHANNEL_ID)
+        // Under the channel lock, so a sound picked meanwhile (#518) can't move it mid-post.
+        val posted = channels.withChannel(alert.calendarId) { channelId -> notify(alert, channelId, title, text) }
+        if (posted == null) {
+            Log.i(TAG, "Dropped the reminder of event ${alert.eventId}: no channel for calendar ${alert.calendarId}")
+        }
+    }
+
+    private fun notify(alert: ReminderAlert, channelId: String, title: String, text: String) {
+        val notification = NotificationCompat.Builder(context, channelId)
             .setSmallIcon(R.drawable.ic_notification)
             .setContentTitle(title)
             .setContentText(text)
@@ -153,7 +160,7 @@ class ReminderNotifier @Inject constructor(
     private fun cancelLegacy(alert: ReminderAlert) {
         val manager = NotificationManagerCompat.from(context)
         manager.activeNotifications
-            .filter { it.id == NOTIFICATION_ID && it.notification.channelId == CHANNEL_ID }
+            .filter { it.id == NOTIFICATION_ID && it.notification.channelId == LEGACY_REMINDER_CHANNEL_ID }
             .filter { !it.notification.extras.containsKey(EXTRA_REMINDER_KEY) }
             .filter { it.notification.`when` == alert.beginMillis }
             .filter { it.notification.extras.getCharSequence(NotificationCompat.EXTRA_TITLE)?.toString() == displayTitle(alert) }
@@ -181,21 +188,8 @@ class ReminderNotifier @Inject constructor(
         PendingIntent.FLAG_UPDATE_CURRENT or PendingIntent.FLAG_IMMUTABLE,
     )
 
-    /** Channel creation is idempotent; re-running refreshes the localized name. */
-    private fun ensureChannel() {
-        val channel = NotificationChannel(
-            CHANNEL_ID,
-            context.getString(R.string.reminder_channel_name),
-            NotificationManager.IMPORTANCE_HIGH,
-        ).apply {
-            description = context.getString(R.string.reminder_channel_description)
-        }
-        NotificationManagerCompat.from(context).createNotificationChannel(channel)
-    }
-
     private companion object {
         const val TAG = "ReminderNotifier"
-        const val CHANNEL_ID = "reminders"
 
         // One id, distinct tags: the tag (occurrence) already keys the
         // notification, so a fixed id keeps cancellation/replacement simple.

app/src/main/java/de/jeanlucmakiola/calendula/data/reminders/ReminderScanner.kt

@@ -43,6 +43,7 @@ class ReminderScanner @Inject constructor(
     private val source: ReminderInstanceSource,
     private val calendarDataSource: CalendarDataSource,
     private val notifier: ReminderNotifier,
+    private val channels: ReminderChannels,
     private val snoozes: ReminderSnoozeScheduler,
     private val alarms: ReminderAlarmScheduler,
     private val state: ReminderStatePrefs,
@@ -85,10 +86,14 @@ class ReminderScanner @Inject constructor(
             return
         }
 
+        syncChannels()
         val lookahead = reminderQueryHorizon(LOOKAHEAD_MILLIS, source.longestReminderMinutes())
         // Reach into the past too: an all-day "at time of event" encodes to a
         // negative offset, and a catch-up pass needs the occurrences it missed.
+        // Calendars muted in-app (#272) plan nothing, so they arm no wake-ups.
+        val muted = settingsPrefs.mutedReminderCalendarIds.first()
         val occurrences = source.occurrences(now - PAST_WINDOW_MILLIS, now + lookahead)
+            .filter { it.calendarId !in muted }
         val planned = planReminders(
             instances = occurrences,
             minutesByEvent = source.reminderMinutes(occurrences.map { it.eventId })
@@ -117,6 +122,19 @@ class ReminderScanner @Inject constructor(
         alarms.scheduleScan(schedule.nextAlarmMillis)
     }
 
+    /**
+     * A provider change re-scans, so a calendar added, renamed or removed keeps
+     * its channel in step here. Skipped while reminders are off, when the
+     * channels have nothing to do. A failure never costs the reminders.
+     */
+    private fun syncChannels() {
+        try {
+            channels.sync()
+        } catch (e: Exception) {
+            Log.w(TAG, "Reminder channel sync failed", e)
+        }
+    }
+
     private fun hasReadCalendar(): Boolean = context.hasPermission(Manifest.permission.READ_CALENDAR)
 
     /**

app/src/main/java/de/jeanlucmakiola/calendula/ui/CalendarHost.kt

@@ -485,9 +485,8 @@ fun CalendarHost(
             movableCalendarIds = movableCalendarIds,
             dragEnabled = dragToReschedule,
             move = { reschedule.move(it) },
-            inFlight = reschedule.inFlight,
+            drops = reschedule.drops,
             undoStarted = reschedule.undoStarted,
-            abandoned = reschedule.abandoned,
             edit = onEditEvent,
         )
     }

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

@@ -1,5 +1,6 @@
 package de.jeanlucmakiola.calendula.ui.common
 
+import android.content.Context
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.remember
 import androidx.compose.ui.platform.LocalContext
@@ -72,11 +73,13 @@ fun accountGroupTitle(group: CalendarAccountGroup): String {
 @Composable
 fun sourceAppName(accountType: String): String {
     val context = LocalContext.current
-    return remember(accountType) {
-        val pm = context.packageManager
-        val packages = sourceAppPackages(context, accountType)
-        packages.firstNotNullOfOrNull { pkg ->
-            runCatching { pm.getApplicationLabel(pm.getApplicationInfo(pkg, 0)).toString() }.getOrNull()
-        } ?: accountType
-    }
+    return remember(accountType) { sourceAppLabel(context, accountType) }
+}
+
+/** [sourceAppName] outside composition, e.g. for notification channel groups. */
+fun sourceAppLabel(context: Context, accountType: String): String {
+    val pm = context.packageManager
+    return sourceAppPackages(context, accountType).firstNotNullOfOrNull { pkg ->
+        runCatching { pm.getApplicationLabel(pm.getApplicationInfo(pkg, 0)).toString() }.getOrNull()
+    } ?: accountType
 }

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

@@ -8,9 +8,9 @@ import java.util.Locale
  * out in [locale]'s own order, with the year shown only when [date] falls outside
  * [currentYear].
  *
- * Pass [skeleton] *without* a year field — "LLLL" for a month, "EEEdMMM" for a
- * day. A skeleton is a field list, so wanting the year is just asking for one
- * more field; the locale still decides where it lands ("July 2026" vs "2026年7月").
+ * Pass [skeleton] *without* a year field, e.g. "LLLL" for a month. A skeleton
+ * is a field list, so wanting the year is just asking for one more field; the
+ * locale still decides where it lands ("July 2026" vs "2026年7月").
  *
  * Dropping the year in the current year is the one bit of policy here: the title
  * sits directly above a grid that already says which year it is, and the year's

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

@@ -90,6 +90,9 @@ fun EventMoveHost(
         MoveOutcome.Undone -> stringResource(R.string.event_move_undone)
         MoveOutcome.WriteDenied -> stringResource(R.string.event_move_write_denied)
         MoveOutcome.Gone -> stringResource(R.string.event_move_gone)
+        MoveOutcome.Stale -> stringResource(R.string.event_move_stale)
+        MoveOutcome.Skipped -> stringResource(R.string.event_move_skipped)
+        MoveOutcome.QueueFull -> stringResource(R.string.event_move_queue_full)
         MoveOutcome.BlockedSeriesEnd -> stringResource(R.string.event_move_blocked_series_end)
         MoveOutcome.BlockedCancelledSeries -> stringResource(R.string.event_move_blocked_cancelled_series)
         MoveOutcome.Failed -> stringResource(R.string.event_move_failed)

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

@@ -1,12 +1,15 @@
 package de.jeanlucmakiola.calendula.ui.common
 
 import androidx.compose.animation.core.animateFloatAsState
+import kotlinx.coroutines.delay
+import androidx.compose.animation.core.tween
+import androidx.compose.runtime.rememberUpdatedState
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.Immutable
 import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.compositionLocalOf
 import androidx.compose.runtime.getValue
-import androidx.compose.runtime.mutableIntStateOf
+import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.res.stringResource
@@ -16,6 +19,7 @@ import de.jeanlucmakiola.calendula.R
 import de.jeanlucmakiola.calendula.domain.EventInstance
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
+import java.util.concurrent.atomic.AtomicLong
 
 /**
  * Drag-to-reschedule wiring (#68), provided once at `CalendarHost` and read by
@@ -37,24 +41,18 @@ class EventMoveScope(
     val dragEnabled: Boolean,
     /**
      * Hand a drop to the writer. Returns nothing on purpose: a drop is answered
-     * before its write resolves, so [abandoned] — not a return value — is what
-     * tells a held copy that nothing landed.
+     * before its write resolves, so [drops] — not a return value — is what tells
+     * a held copy whether anything landed.
      */
     val move: (MoveRequest) -> Unit,
     /**
-     * True while a dropped event is being written, including the time its scope
-     * dialog is up. A flow rather than a value so this scope stays the same
-     * object across a move — every visible block reads it as a composition local.
+     * Each drop's progress by its token — see `RescheduleViewModel.drops`. A flow
+     * rather than a value so this scope stays the same object across a move —
+     * every visible block reads it as a composition local.
      */
-    val inFlight: StateFlow<Boolean>,
-    /** Ticks when an undo write begins — see `RescheduleViewModel.undoStarted`. */
-    val undoStarted: StateFlow<Int>,
-    /**
-     * Ticks when a drop ends with nothing landing — see
-     * `RescheduleViewModel.abandoned`. [move] answers before the write is
-     * resolved, so this is what tells a held copy to stop waiting.
-     */
-    val abandoned: StateFlow<Int>,
+    val drops: StateFlow<DropStates>,
+    /** The undo write that just began — see `RescheduleViewModel.undoStarted`. */
+    val undoStarted: StateFlow<UndoStart?>,
     /** Open an event in the edit form — the pointer-free route to the same change. */
     val edit: (EventInstance) -> Unit,
 ) {
@@ -63,30 +61,42 @@ class EventMoveScope(
 
 val LocalEventMove = compositionLocalOf<EventMoveScope?> { null }
 
-private val NEVER_IN_FLIGHT = MutableStateFlow(false)
+private val moveTokens = AtomicLong()
 
-private val NEVER_UNDONE = MutableStateFlow(0)
+/** A fresh identity for one drop or undo, unique for the process. */
+fun nextMoveToken(): Long = moveTokens.incrementAndGet()
 
-private val NEVER_ABANDONED = MutableStateFlow(0)
+/** How many abandoned drops [DropStates] remembers — far more than can be on screen at once. */
+private const val ABANDONED_KEPT = 32
 
-/**
- * Whether a dropped event is still being written — false wherever moving is off.
- * The drag overlays hold a landed block on its target for this window.
- */
-@Composable
-fun moveInFlight(): Boolean {
-    val flow = LocalEventMove.current?.inFlight ?: NEVER_IN_FLIGHT
-    return flow.collectAsStateWithLifecycle().value
+/** Per-drop progress, by token — see `RescheduleViewModel.drops`. */
+@Immutable
+data class DropStates(
+    val pending: Set<Long> = emptySet(),
+    val abandoned: Set<Long> = emptySet(),
+) {
+    fun started(token: Long): DropStates = copy(pending = pending + token)
+
+    fun ended(token: Long, landed: Boolean): DropStates = copy(
+        pending = pending - token,
+        // Insertion-ordered, so the oldest go first.
+        abandoned = if (landed) abandoned else (abandoned + token).let { kept ->
+            if (kept.size > ABANDONED_KEPT) kept.drop(kept.size - ABANDONED_KEPT).toSet() else kept
+        },
+    )
 }
 
+private val NO_DROPS = MutableStateFlow(DropStates())
+
+private val NEVER_UNDONE = MutableStateFlow<UndoStart?>(null)
+
 /**
- * How many drops have ended with nothing landing. Read as a plain count so a
- * drag overlay can capture it at the moment of the drop and tell, later, whether
- * *its own* drop was one of them.
+ * Every drop's progress — empty wherever moving is off. A drag overlay keeps
+ * the token of its own drop and holds its copy while that token is pending.
  */
 @Composable
-fun abandonedMoves(): Int {
-    val flow = LocalEventMove.current?.abandoned ?: NEVER_ABANDONED
+fun dropStates(): DropStates {
+    val flow = LocalEventMove.current?.drops ?: NO_DROPS
     return flow.collectAsStateWithLifecycle().value
 }
 
@@ -95,17 +105,53 @@ fun abandonedMoves(): Int {
  * this composable came on screen.
  */
 @Composable
-fun OnUndoStarted(onUndo: () -> Unit) {
+fun OnUndoStarted(onUndo: (UndoStart) -> Unit) {
     val flow = LocalEventMove.current?.undoStarted ?: NEVER_UNDONE
-    val tick by flow.collectAsStateWithLifecycle()
-    var seen by remember { mutableIntStateOf(tick) }
-    LaunchedEffect(tick) {
-        if (tick == seen) return@LaunchedEffect
-        seen = tick
-        onUndo()
+    val start by flow.collectAsStateWithLifecycle()
+    var seen by remember { mutableStateOf(start) }
+    LaunchedEffect(start) {
+        val started = start
+        if (started == null || started == seen) return@LaunchedEffect
+        seen = started
+        onUndo(started)
     }
 }
 
+/**
+ * The life of a drop parked by a newer pickup (#494): held while its [token]
+ * is pending, then a beat after the grid [seated] it — or [timeoutMillis] if it
+ * never does — handed over and faded, then released. Returns the copy's alpha.
+ * An abandoned drop skips the wait; nothing is coming to seat it.
+ */
+@Composable
+fun rememberHeldSettle(
+    token: Long,
+    seated: Boolean,
+    timeoutMillis: Long,
+    onHandOver: () -> Unit,
+    onRelease: () -> Unit,
+): Float {
+    val drops = dropStates()
+    val pending = token in drops.pending
+    val abandoned = token in drops.abandoned
+    val handOver by rememberUpdatedState(onHandOver)
+    val release by rememberUpdatedState(onRelease)
+    var fading by remember(token) { mutableStateOf(false) }
+    LaunchedEffect(token, pending, abandoned, seated) {
+        if (pending) return@LaunchedEffect
+        if (!abandoned) delay(if (seated) SETTLE_GRACE_MILLIS else timeoutMillis)
+        fading = true
+        handOver()
+        delay(SETTLE_FADE_MILLIS.toLong())
+        release()
+    }
+    return animateFloatAsState(
+        targetValue = if (fading) 0f else 1f,
+        animationSpec = tween(SETTLE_FADE_MILLIS),
+        label = "held-settle",
+    ).value
+}
+
 /** Opacity the source block keeps while its floating copy travels. */
 const val GHOST_ALPHA: Float = 0.3f
 

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

@@ -32,6 +32,7 @@ import kotlinx.coroutines.flow.asStateFlow
 import kotlinx.coroutines.flow.catch
 import kotlinx.coroutines.flow.flowOn
 import kotlinx.coroutines.flow.map
+import kotlinx.coroutines.flow.update
 import kotlinx.coroutines.launch
 import kotlinx.datetime.DateTimeUnit
 import kotlinx.datetime.LocalDate
@@ -40,12 +41,21 @@ import kotlinx.datetime.atStartOfDayIn
 import kotlinx.datetime.plus
 import kotlinx.datetime.toLocalDateTime
 import kotlin.coroutines.cancellation.CancellationException
+import kotlin.time.Duration.Companion.seconds
 import kotlin.time.Instant
+import kotlin.time.TimeMark
+import kotlin.time.TimeSource
 import javax.inject.Inject
 
 private const val MILLIS_PER_MINUTE = 60_000
 private const val MINUTES_PER_DAY = 24 * 60
 
+/** How many drops may wait behind the one in flight before more are refused. */
+private const val MAX_QUEUED = 8
+
+/** How long after a write its event's drawn times may still be the old ones. */
+private val RECENT_WRITE = 3.seconds
+
 /** Where a dragged event should land. */
 sealed interface MoveTarget {
     /** A new start instant — a timeline drag, which moves time and day at once. */
@@ -74,6 +84,10 @@ data class MoveRequest(
     val beginMillis: Long,
     val endMillis: Long,
     val target: MoveTarget,
+    /** Whether the dragged occurrence is all-day, which decides the zone its day is read in. */
+    val isAllDay: Boolean,
+    /** The drop's own identity, from [nextMoveToken], which the view holding its copy waits on. */
+    val token: Long,
 )
 
 /**
@@ -92,8 +106,13 @@ data class MoveUndo(
     val moved: EventForm,
     /** The form as it stood before the move. */
     val restored: EventForm,
+    /** The token of the drop this undoes, so the view that drew it carries the right chip back. */
+    val dropToken: Long,
 )
 
+/** An undo write that just began: its own [token], and the [dropToken] of the drop it undoes. */
+data class UndoStart(val token: Long, val dropToken: Long)
+
 sealed interface MoveOutcome {
     /**
      * Written. [startMillis] is where the dragged occurrence now begins, for the
@@ -115,6 +134,19 @@ sealed interface MoveOutcome {
     /** The event vanished (sync, another device) between the read and the write. */
     data object Gone : MoveOutcome
 
+    /** Drops that waited behind a scope dialog, cancelled rather than run after it (#494). */
+    data object Skipped : MoveOutcome
+
+    /** More drops waiting than the queue holds; this one was not taken. */
+    data object QueueFull : MoveOutcome
+
+    /**
+     * The drop's recurring occurrence may no longer be where it was picked up —
+     * its series was just written — and can't be followed there, so it is not
+     * written (#494).
+     */
+    data object Stale : MoveOutcome
+
     /** The drop would push the series past its own `UNTIL`, generating nothing. */
     data object BlockedSeriesEnd : MoveOutcome
 
@@ -152,36 +184,32 @@ class RescheduleViewModel @Inject constructor(
 
     private val _inFlight = MutableStateFlow(false)
 
-    /**
-     * True from the moment a drop is accepted until its write settles — the
-     * window the dropped block holds its landing position for.
-     */
+    /** True while any drop or undo runs or waits — what the confirmation chip holds for. */
     val inFlight: StateFlow<Boolean> = _inFlight.asStateFlow()
 
-    private val _abandoned = MutableStateFlow(0)
+    private val _drops = MutableStateFlow(DropStates())
 
     /**
-     * Ticks when a drop ends with nothing on the target day: refused outright,
-     * refused before the write, written and failed, or its scope dialog
-     * dismissed. [move] answers before any of that is known, so without this
-     * signal the view that drew the drop held its copy out for the full settle
-     * timeout waiting for a grid that was never going to draw it (#253).
+     * Each drop's own state, by its [MoveRequest.token]: pending from the moment
+     * it is accepted until its write settles, and abandoned once it ends with
+     * nothing on the target day — refused, failed, or its scope dialog dismissed.
+     * Per drop, so a queued drop's held copy waits on its own write and is never
+     * let go by another drop's failure (#253, #494).
      */
-    val abandoned: StateFlow<Int> = _abandoned.asStateFlow()
+    val drops: StateFlow<DropStates> = _drops.asStateFlow()
 
-    private val _undoStarted = MutableStateFlow(0)
+    private val _undoStarted = MutableStateFlow<UndoStart?>(null)
 
     /**
-     * Ticks the moment an undo write begins, before the provider has anything to
+     * An undo write the moment it begins, before the provider has anything to
      * re-read, so the view that drew the drop can carry its chip back rather than
-     * let it reappear on the old day.
+     * let it reappear on the old day. Its fate then reads off [drops].
      */
-    val undoStarted: StateFlow<Int> = _undoStarted.asStateFlow()
+    val undoStarted: StateFlow<UndoStart?> = _undoStarted.asStateFlow()
 
     /**
-     * Set from the moment a drop is accepted until its write settles. Two drops
-     * of the same recurring event inside that window would compute their shift
-     * from the same pre-move occurrence, and the shifts would compound.
+     * Set while a drop is being prepared, waits on its scope dialog, or is
+     * written. Drops arriving in that window wait in [queue] and run in order.
      */
     private var busy = false
         set(value) {
@@ -189,6 +217,22 @@ class RescheduleViewModel @Inject constructor(
             _inFlight.value = value
         }
 
+    /** Whether a move has been announced since the pipeline was last idle — see [report]. */
+    private var movedThisRun = false
+
+    /** Outcomes waiting for the chip, shown one after another as each is consumed. */
+    private val notices = ArrayDeque<MoveOutcome>()
+
+    /**
+     * When each event's series (by id) or single occurrence (by id and begin)
+     * was last written. The grid draws the old times until it re-reads, so a
+     * drop on a recurring event written moments ago may carry stale times (#494).
+     */
+    private val written = mutableMapOf<Pair<Long, Long?>, TimeMark>()
+
+    /** Drops that arrived while another was in flight, oldest first (#494). */
+    private val queue = ArrayDeque<MoveRequest>()
+
     /**
      * The calendars whose events may be dragged. Nothing below the UI guards
      * this, so a block outside this set registers no drag gesture at all.
@@ -219,38 +263,50 @@ class RescheduleViewModel @Inject constructor(
     }
 
     /**
-     * Take a drop, unless one is already being written. False means nothing will
-     * be written; [abandoned] ticks for that refusal too, so a held copy is let
-     * go by the one signal rather than by every caller remembering to.
+     * Take a drop: run it now, or queue it behind the ones in flight. False means
+     * nothing will be written — the queue is full — and the drop is marked
+     * abandoned in [drops], so its held copy is let go by the one signal rather
+     * than by every caller remembering to.
      *
      * The Boolean is diagnostic — the tests read it, [EventMoveScope] does not
-     * hand it on. A caller that gated on it would be back to releasing its copy
-     * from two places, and it answers before the write is resolved anyway.
+     * hand it on. It answers before the write is resolved anyway.
      */
     fun move(request: MoveRequest): Boolean {
-        if (busy || _scopePrompt.value != null) {
-            _abandoned.value += 1
+        if (queue.size >= MAX_QUEUED) {
+            _drops.update { it.ended(request.token, landed = false) }
+            report(MoveOutcome.QueueFull)
             return false
         }
+        if (_scopePrompt.value != null) {
+            _drops.update { it.ended(request.token, landed = false) }
+            report(MoveOutcome.Skipped)
+            return false
+        }
+        _drops.update { it.started(request.token) }
+        if (busy) queue.addLast(request) else run(request)
+        return true
+    }
+
+    private fun run(request: MoveRequest) {
         busy = true
         viewModelScope.launch {
             val prepared = prepare(request)
             if (prepared == null) {
-                _abandoned.value += 1
-                busy = false
+                settle(request.token, landed = false)
                 return@launch
             }
             // A cancelled series only moves as a whole (#388).
             val seriesOnly = !prepared.original.canSaveApartFromSeries()
             if (!prepared.isRecurring || (seriesOnly && prepared.canRealign)) {
-                write(prepared, RecurringWriteScope.AllEvents)
-                busy = false
+                settle(request.token, write(prepared, RecurringWriteScope.AllEvents))
             } else if (seriesOnly) {
-                _outcome.value = MoveOutcome.BlockedCancelledSeries
-                _abandoned.value += 1
-                busy = false
+                report(MoveOutcome.BlockedCancelledSeries)
+                settle(request.token, landed = false)
             } else {
-                // Still busy: the scope dialog is now the thing in flight.
+                // Still busy: the scope dialog is now the thing in flight. Drops
+                // waiting behind it are cancelled, not held behind a question
+                // about another event.
+                skipQueued()
                 pending = prepared
                 _scopePrompt.value = MoveScopePrompt(
                     occurrenceOnly = !prepared.canRealign,
@@ -258,7 +314,6 @@ class RescheduleViewModel @Inject constructor(
                 )
             }
         }
-        return true
     }
 
     /** Answer the scope dialog. */
@@ -269,35 +324,92 @@ class RescheduleViewModel @Inject constructor(
         pending = null
         _scopePrompt.value = null
         viewModelScope.launch {
-            write(prepared, scope)
-            busy = false
+            settle(prepared.request.token, write(prepared, scope))
         }
     }
 
     /** Dismiss the scope dialog without writing. */
     fun cancelScope() {
+        val prepared = pending ?: return
         pending = null
-        busy = false
         _scopePrompt.value = null
-        _abandoned.value += 1
+        settle(prepared.request.token, landed = false)
+    }
+
+    /** End the drop [token], then run the next queued one, if any. */
+    private fun settle(token: Long, landed: Boolean) {
+        _drops.update { it.ended(token, landed) }
+        // Straight on to the next, so busy never reads false between two drops.
+        val next = queue.removeFirstOrNull()
+        if (next != null) {
+            run(next)
+        } else {
+            busy = false
+            movedThisRun = false
+        }
+    }
+
+    private fun skipQueued() {
+        if (queue.isEmpty()) return
+        val skipped = queue.map { it.token }
+        queue.clear()
+        _drops.update { states -> skipped.fold(states) { acc, token -> acc.ended(token, landed = false) } }
+        report(MoveOutcome.Skipped)
+    }
+
+    /**
+     * Queue [outcome] for the chip. While drops run back to back only the first
+     * move is announced, so its Undo stays on offer; every failure gets its own
+     * turn after it, since the grid shows what moved but only the chip says what
+     * didn't. A later write to the announced move's event takes that Undo away,
+     * as putting the event back would undo the later move too.
+     */
+    private fun report(outcome: MoveOutcome, eventId: Long? = null) {
+        if (outcome is MoveOutcome.Moved) {
+            if (movedThisRun) {
+                dropUndoFor(eventId)
+                return
+            }
+            movedThisRun = true
+        } else if (outcome == (notices.lastOrNull() ?: _outcome.value)) {
+            return
+        }
+        if (_outcome.value == null) _outcome.value = outcome else notices.addLast(outcome)
+    }
+
+    private fun dropUndoFor(eventId: Long?) {
+        fun MoveOutcome.withoutUndo(): MoveOutcome =
+            if (this is MoveOutcome.Moved && undo?.eventId == eventId) copy(undo = null) else this
+        _outcome.value = _outcome.value?.withoutUndo()
+        val rest = notices.map { it.withoutUndo() }
+        notices.clear()
+        notices.addAll(rest)
+    }
+
+    private fun markWritten(eventId: Long, beginMillis: Long?) {
+        written[eventId to beginMillis] = TimeSource.Monotonic.markNow()
+    }
+
+    private fun writtenRecently(eventId: Long, beginMillis: Long): Boolean {
+        written.entries.removeAll { it.value.elapsedNow() > RECENT_WRITE }
+        return (eventId to null) in written || (eventId to beginMillis) in written
     }
 
     /**
      * Put a completed move back where it came from. The outcome stands until the
      * inverse write reports back, so the one chip changes what it says rather
      * than closing and reopening. False when another write is already running —
-     * the chip hides its action for that window, so this is the backstop.
-     *
-     * [abandoned] ticks once an inverse that *started* fails to land: [undoStarted]
-     * has sent the chip back on its journey by then and nothing else will seat it.
-     * A refusal ticks nothing — it launched no journey of its own, and the counter
-     * is global, so a tick here would release some other drop's held copy before
-     * the grid has drawn it.
+     * the chip hides its action for that window, so this is the backstop. An
+     * undo is a journey of its own: [undoStarted] names its token, and [drops]
+     * reports whether it landed.
      */
     fun undo(undo: MoveUndo): Boolean {
         if (busy) return false
+        val token = nextMoveToken()
+        _drops.update { it.started(token) }
         busy = true
-        _undoStarted.value += 1
+        _undoStarted.value = UndoStart(token, undo.dropToken)
+        markWritten(undo.eventId, null)
         viewModelScope.launch {
             _outcome.value = try {
                 repository.updateEvent(undo.eventId, undo.moved, undo.restored)
@@ -311,33 +423,40 @@ class RescheduleViewModel @Inject constructor(
             } catch (e: Exception) {
                 MoveOutcome.Failed
             }
-            // Read off the outcome, the way [write] does — no second copy of the
-            // same fact to drift from it.
-            if (_outcome.value !is MoveOutcome.Undone) _abandoned.value += 1
-            busy = false
+            settle(token, landed = _outcome.value is MoveOutcome.Undone)
         }
         return true
     }
 
-    /** Clear the outcome once the screen has shown it. */
+    /** Clear the outcome once the screen has shown it, bringing on the next one waiting. */
     fun consumeOutcome() {
-        _outcome.value = null
+        _outcome.value = notices.removeFirstOrNull()
     }
 
-    private suspend fun prepare(request: MoveRequest): PreparedMove? {
+    private suspend fun prepare(dropped: MoveRequest): PreparedMove? {
+        val zone = zoneSource.current()
         val detail = try {
-            repository.eventDetail(request.eventId)
+            repository.eventDetail(dropped.eventId)
         } catch (e: CancellationException) {
             throw e
         } catch (e: NoSuchEventException) {
-            _outcome.value = MoveOutcome.Gone
+            report(MoveOutcome.Gone)
             return null
         } catch (e: Exception) {
-            _outcome.value = MoveOutcome.Failed
+            report(MoveOutcome.Failed)
             return null
         }
+        // The drop carries the times the grid drew, which an earlier write may
+        // have moved on since (#494).
+        val request = if (detail.rrule == null || detail.isException) {
+            followed(dropped, detail, zone)
+        } else if (writtenRecently(dropped.eventId, dropped.beginMillis)) {
+            report(MoveOutcome.Stale)
+            return null
+        } else {
+            dropped
+        }
 
-        val zone = zoneSource.current()
         val original = detail.toEditForm(request.beginMillis, request.endMillis, zone)
         val shifted = when (val target = request.target) {
             is MoveTarget.Start -> original.shiftedTo(target.instant, zone)
@@ -350,7 +469,7 @@ class RescheduleViewModel @Inject constructor(
         // The UNTIL check is deferred to the write, which knows how far the move
         // reaches and so which date has to clear it.
         if ((shifted.problems(zone) - EventFormProblem.RecurrenceEndsBeforeStart).isNotEmpty()) {
-            _outcome.value = MoveOutcome.Failed
+            report(MoveOutcome.Failed)
             return null
         }
 
@@ -395,14 +514,14 @@ class RescheduleViewModel @Inject constructor(
         )
     }
 
-    private suspend fun write(prepared: PreparedMove, scope: RecurringWriteScope) {
+    /** Write [prepared] in [scope]; true when it landed. */
+    private suspend fun write(prepared: PreparedMove, scope: RecurringWriteScope): Boolean {
         val request = prepared.request
         if (endsBeforeItStarts(prepared, scope)) {
-            _outcome.value = MoveOutcome.BlockedSeriesEnd
-            _abandoned.value += 1
-            return
+            report(MoveOutcome.BlockedSeriesEnd)
+            return false
         }
-        _outcome.value = try {
+        val outcome = try {
             when {
                 !prepared.isRecurring || scope == RecurringWriteScope.AllEvents ->
                     repository.updateEvent(request.eventId, prepared.original, prepared.updated)
@@ -437,9 +556,37 @@ class RescheduleViewModel @Inject constructor(
         } catch (e: Exception) {
             MoveOutcome.Failed
         }
-        // Nothing landed, so the copy the view is holding has nothing to fade
-        // into — let it go now rather than at the end of the settle timeout.
-        if (_outcome.value !is MoveOutcome.Moved) _abandoned.value += 1
+        if (outcome is MoveOutcome.Moved) {
+            markWritten(request.eventId, request.beginMillis.takeIf { scope == RecurringWriteScope.ThisEvent && prepared.isRecurring })
+        }
+        report(outcome, request.eventId)
+        return outcome is MoveOutcome.Moved
+    }
+
+    /**
+     * A one-off [dropped] rebased onto where its event now is, so the last drop
+     * wins: absolute targets stand as they are, and a whole-day shift is re-aimed
+     * at the day it was dropped on. Unchanged when the event hasn't moved.
+     */
+    private fun followed(dropped: MoveRequest, detail: EventDetail, zone: TimeZone): MoveRequest {
+        val now = detail.instance
+        val target = when (val target = dropped.target) {
+            is MoveTarget.ByDays -> {
+                // Each day read the way its own kind anchors it: all-day at UTC.
+                val aimed = Instant.fromEpochMilliseconds(dropped.beginMillis)
+                    .toLocalDateTime(if (dropped.isAllDay) TimeZone.UTC else zone).date
+                    .plus(target.days, DateTimeUnit.DAY)
+                val from = now.start.toLocalDateTime(if (now.isAllDay) TimeZone.UTC else zone).date
+                MoveTarget.ByDays((aimed.toEpochDays() - from.toEpochDays()).toInt())
+            }
+            else -> target
+        }
+        return dropped.copy(
+            beginMillis = now.start.toEpochMilliseconds(),
+            endMillis = now.end.toEpochMilliseconds(),
+            target = target,
+            isAllDay = now.isAllDay,
+        )
     }
 
     /**
@@ -506,6 +653,7 @@ class RescheduleViewModel @Inject constructor(
                 eventId = prepared.request.eventId,
                 moved = prepared.updated,
                 restored = prepared.original,
+                dropToken = prepared.request.token,
             )
         } else {
             null

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

@@ -20,6 +20,7 @@ import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.Stable
 import androidx.compose.runtime.derivedStateOf
 import androidx.compose.runtime.getValue
+import androidx.compose.runtime.key
 import androidx.compose.runtime.mutableStateListOf
 import androidx.compose.runtime.mutableIntStateOf
 import androidx.compose.runtime.mutableStateOf
@@ -60,7 +61,6 @@ import de.jeanlucmakiola.floret.identity.LocalFloretDarkTheme
 import de.jeanlucmakiola.floret.identity.rememberReduceMotion
 import de.jeanlucmakiola.floret.locale.currentLocale
 import kotlinx.coroutines.delay
-import kotlinx.coroutines.flow.StateFlow
 import kotlinx.datetime.DateTimeUnit
 import kotlinx.datetime.LocalDate
 import kotlinx.datetime.atStartOfDayIn
@@ -139,9 +139,17 @@ data class StripDrag(val event: EventInstance, val dayShift: Int = 0, val overGr
 sealed interface StripDrop {
     val event: EventInstance
 
-    data class Days(override val event: EventInstance, val days: Int) : StripDrop
+    /** The drop's identity, which its held copy waits on. */
+    val token: Long
 
-    data class Timed(override val event: EventInstance, val start: Instant, val end: Instant) : StripDrop
+    data class Days(override val event: EventInstance, val days: Int, override val token: Long) : StripDrop
+
+    data class Timed(
+        override val event: EventInstance,
+        val start: Instant,
+        val end: Instant,
+        override val token: Long,
+    ) : StripDrop
 }
 
 /** The event a long press left selected (#141). */
@@ -297,7 +305,9 @@ data class TimelineDrop(
     val date: LocalDate,
     val startMin: Int,
     /** Minutes from the event's start to the dragged block's top edge. */
-    val clipOffsetMin: Int = 0,
+    val clipOffsetMin: Int,
+    /** The drop's identity, which its held copy waits on. */
+    val token: Long,
 )
 
 /** The id a drafted block's stand-in event carries, which no provider row has (#153). */
@@ -340,8 +350,37 @@ internal fun draftBlock(draft: EventInstance, date: LocalDate, zone: TimeZone):
 /** Which end of an event a resize handle moves (#141). */
 enum class ResizeEdge { Top, Bottom }
 
+/** A drop parked by a newer pickup while its write still runs — see [TimelineDragController.held]. */
+data class HeldDrop(
+    val copy: TimelineDrag,
+    val token: Long,
+    val instanceId: Long,
+    /** The event row and start the drop came from, as [TimelineDragController.ghosts] matches them. */
+    val origin: Pair<Long, Instant>,
+    /** A resize's new end, which has to have landed too before the drop counts as seated. */
+    val end: Instant?,
+    /** Whether the grid now draws the drop at its landing slot. */
+    val seated: Boolean = false,
+    val handedOver: Boolean = false,
+) {
+    fun ghosts(block: TimedBlock): Boolean = block.event.instanceId == instanceId ||
+        (block.event.eventId == origin.first && block.event.start == origin.second)
+}
+
+/** A strip drop parked by a newer one while its write still runs — see [TimelineDragController.heldStrips]. */
+data class HeldStrip(val drag: StripDrag, val token: Long, val seated: Boolean = false)
+
+/** An event's new start and end, as a resize leaves them. */
+data class ResizedSpan(val start: Instant, val end: Instant)
+
 /** Where a finished resize asks its event to begin and end. */
-data class TimelineResizeDrop(val event: EventInstance, val start: Instant, val end: Instant)
+data class TimelineResizeDrop(
+    val event: EventInstance,
+    val start: Instant,
+    val end: Instant,
+    /** The drop's identity, which its held copy waits on. */
+    val token: Long,
+)
 
 /**
  * [event] resized by its [edge] to the span [startMin]..+[spanMin] from [date]'s
@@ -352,17 +391,16 @@ data class TimelineResizeDrop(val event: EventInstance, val start: Instant, val
  * it was drawn (see [repicked]). An end takes a pass the grid draws at the drop
  * point, so the block settles under the finger.
  */
-internal fun resizedDrop(
+internal fun resizedSpan(
     event: EventInstance,
     edge: ResizeEdge?,
     date: LocalDate,
     startMin: Int,
     spanMin: Int,
     zone: TimeZone,
-): TimelineResizeDrop {
+): ResizedSpan {
     val drawn = wallClockSpan(event, zone)
-    return TimelineResizeDrop(
-        event = event,
+    return ResizedSpan(
         start = if (edge == ResizeEdge.Top) {
             event.start.toFormTime(zone).repicked(
                 wallClockTime(date, startMin),
@@ -513,6 +551,14 @@ class TimelineDragController {
      */
     private var settledOrigin: Pair<Long, Instant>? by mutableStateOf(null)
 
+    /**
+     * Earlier drops still being written when another block was picked up. They
+     * keep their copy and their ghost until their own token settles, rather than
+     * vanishing and flashing back at the old slot (#494).
+     */
+    var held: List<HeldDrop> by mutableStateOf(emptyList())
+        private set
+
     /** How long a block drafted on an empty slot starts out, in minutes (#153). */
     var draftMinutes: Int = SettingsPrefs.DEFAULT_EVENT_DURATION
 
@@ -611,14 +657,8 @@ class TimelineDragController {
     var settlingSelected: Boolean = false
         private set
 
-    /**
-     * The abandoned-move counter, read at the drop so the mark can't be a
-     * composition behind the tick it is compared against.
-     */
-    var abandonedTicks: StateFlow<Int>? = null
-
-    /** What [abandonedTicks] stood at when the settling drop was let go. */
-    var settledAbandonedMark: Int = 0
+    /** The token of the drop [settling] waits on. */
+    var settledToken: Long = 0L
         private set
 
     private var source: TimedBlock? = null
@@ -661,8 +701,12 @@ class TimelineDragController {
     var stripSeated: Boolean by mutableStateOf(false)
         private set
 
-    /** What [abandonedTicks] stood at when [stripSettling] was let go. */
-    var stripAbandonedMark: Int = 0
+    /** Strip drops parked by a newer strip drop while their writes still run (#494). */
+    var heldStrips: List<HeldStrip> by mutableStateOf(emptyList())
+        private set
+
+    /** The token of the drop [stripSettling] waits on. */
+    var stripToken: Long = 0L
         private set
 
     /** The shown day the finger picked the strip bar up on. */
@@ -687,7 +731,7 @@ class TimelineDragController {
         dragDuration = (block.event.end - block.event.start).coerceAtLeast(Duration.ZERO)
         dragKept = zone.repeatedHourOffsetAt(block.event.start)
         this.titleLines = titleLines
-        settling = null
+        parkSettling()
         isDragging = true
         liftedInstanceId = block.event.instanceId
         grab = pointerInRoot - blockInRoot
@@ -726,7 +770,7 @@ class TimelineDragController {
         dragDuration = draftMinutes.minutes
         dragKept = null
         titleLines = 1
-        settling = null
+        parkSettling()
         isDragging = true
         liftedInstanceId = event.instanceId
         grab = Offset(0f, geometry.hourPx * STRIP_GRAB_MINUTES / 60f)
@@ -749,16 +793,18 @@ class TimelineDragController {
         val zone = dragZone
         cancel()
         if (held.overGrid && landed != null && zone != null && !landed.edgeOnly) {
-            settle(landed)
-            val start = TimelineDrop(landed.event, landed.date, landed.startMin).startInstant(zone)
-            return StripDrop.Timed(held.event, start, start + draftMinutes.minutes)
+            val token = settle(landed)
+            val start = dropStartInstant(landed.event, landed.date, landed.startMin, clipOffsetMin = 0, zone)
+            return StripDrop.Timed(held.event, start, start + draftMinutes.minutes, token)
         }
         if (held.overGrid || held.dayShift == 0) return null
+        // One still settling keeps its place on the strip until its own write lands (#494).
+        stripSettling?.let { heldStrips = heldStrips + HeldStrip(it, stripToken, stripSeated) }
         stripSettling = held
         stripSeated = false
-        stripAbandonedMark = abandonedTicks?.value ?: 0
+        stripToken = nextMoveToken()
         drops++
-        return StripDrop.Days(held.event, held.dayShift)
+        return StripDrop.Days(held.event, held.dayShift, stripToken)
     }
 
     /** Let the held strip drop go, once the strip shows the event at its new days or the move failed. */
@@ -772,6 +818,21 @@ class TimelineDragController {
         if (stripSettling != null) stripSeated = true
     }
 
+    /** Note that the strip draws the parked strip drop [token] at its new days. */
+    fun seatHeldStrip(token: Long) {
+        if (heldStrips.any { it.token == token && !it.seated }) {
+            heldStrips = heldStrips.map { if (it.token == token) it.copy(seated = true) else it }
+        }
+    }
+
+    /** Let the parked strip drop [token] go. */
+    fun releaseHeldStrip(token: Long) {
+        heldStrips = heldStrips.filterNot { it.token == token }
+    }
+
+    /** Every strip drop still shown at its new days: the parked ones, then the latest. */
+    fun stripPreviews(): List<StripDrag> = heldStrips.map { it.drag } + listOfNotNull(stripDrag ?: stripSettling)
+
     fun move(pointerInRoot: Offset) {
         pointer = pointerInRoot
         if (!pointerMoved && (pointerInRoot - pickupPointer).getDistance() > slopPx) pointerMoved = true
@@ -806,12 +867,36 @@ class TimelineDragController {
      * an event that crosses midnight (#253).
      */
     fun ghosts(block: TimedBlock): Boolean {
+        if (held.any { !it.handedOver && it.ghosts(block) }) return true
         if (liftedInstanceId == null) return false
         if (block.event.instanceId == liftedInstanceId) return true
         val (eventId, start) = settledOrigin ?: return false
         return block.event.eventId == eventId && block.event.start == start
     }
 
+    /** Move a still-settling drop to [held] before a new pickup takes the slot. */
+    private fun parkSettling() {
+        val landed = settling
+        val origin = settledOrigin
+        if (landed != null && origin != null && !landed.event.isDraft) {
+            held = held + HeldDrop(landed, settledToken, landed.event.instanceId, origin, settledEnd, settledOnGrid)
+        }
+        settling = null
+        settledOnGrid = false
+        settledOrigin = null
+        settledEnd = null
+    }
+
+    /** Stop ghosting the held drop [token]'s source while its copy fades. */
+    fun handOverHeld(token: Long) {
+        held = held.map { if (it.token == token) it.copy(handedOver = true) else it }
+    }
+
+    /** Drop the held copy [token] once it has faded. */
+    fun releaseHeld(token: Long) {
+        held = held.filterNot { it.token == token }
+    }
+
     /**
      * What a day column now holds, so a settled drop can tell when the grid has
      * caught up with it. Matched on the landing slot plus either the event row
@@ -819,16 +904,23 @@ class TimelineDragController {
      * blank title matches nothing: every untitled event has one (#253).
      */
     fun noteGrid(date: LocalDate, blocks: List<TimedBlock>) {
+        if (held.any { !it.seated && drawsDrop(it.copy, it.end, date, blocks) }) {
+            held = held.map { if (!it.seated && drawsDrop(it.copy, it.end, date, blocks)) it.copy(seated = true) else it }
+        }
         val landed = settling ?: return
         if (settledOnGrid) return
+        settledOnGrid = drawsDrop(landed, settledEnd, date, blocks)
+    }
+
+    /** Whether [blocks], [date]'s column, draws the drop [landed] where it landed. */
+    private fun drawsDrop(landed: TimelineDrag, end: Instant?, date: LocalDate, blocks: List<TimedBlock>): Boolean {
         // Where this day would draw it, which for a drop clipped at midnight is
         // the day's own start rather than the edge the finger held (#253) — and
         // which for a tail dragged clear of its day is the day before it.
         val offset = (date.toEpochDays() - landed.date.toEpochDays()).toInt()
         val slice = dragSlices(landed.eventStartMin, landed.eventSpanMin, offset..offset)
-            .firstOrNull() ?: return
-        val end = settledEnd
-        settledOnGrid = blocks.any { block ->
+            .firstOrNull() ?: return false
+        return blocks.any { block ->
             block.startMin == slice.startMin &&
                 // A resize may keep its start, so its end has to have landed too.
                 (end == null || block.event.end == end) &&
@@ -855,12 +947,15 @@ class TimelineDragController {
         if (landed == null || landed.slot == origin) return null
         // A draft dropped on a day off screen would vanish, so it stays where it was (#153).
         if (landed.edgeOnly && landed.event.isDraft) return null
-        settle(landed)
-        return TimelineDrop(landed.event, landed.date, landed.startMin, clipOffset)
+        val token = settle(landed)
+        return TimelineDrop(landed.event, landed.date, landed.startMin, clipOffset, token)
     }
 
-    /** Keep [landed]'s copy on the target as [settling] until [release]; [end] is a resize's. */
-    private fun settle(landed: TimelineDrag, end: Instant? = null) {
+    /**
+     * Keep [landed]'s copy on the target as [settling] until [release]; [end] is a
+     * resize's. Returns the drop's fresh token.
+     */
+    private fun settle(landed: TimelineDrag, end: Instant? = null): Long {
         // Landed on midnight to midnight, the event moves to the all-day strip (#296).
         val leavesGrid = !landed.event.isDraft && landed.eventSpanMin > 0 &&
             landed.eventStartMin.mod(MINUTES_PER_DAY) == 0 &&
@@ -873,9 +968,10 @@ class TimelineDragController {
         settling = if (landed.edgeOnly || leavesGrid) landed.copy(pieces = emptyList()) else landed
         liftedInstanceId = landed.event.instanceId
         settledOrigin = landed.event.eventId to landed.event.start
-        settledAbandonedMark = abandonedTicks?.value ?: 0
+        settledToken = nextMoveToken()
         settledEnd = end
         drops++
+        return settledToken
     }
 
     /**
@@ -895,7 +991,7 @@ class TimelineDragController {
         resize = session
         clipOffsetMin = 0
         this.titleLines = titleLines
-        settling = null
+        parkSettling()
         isDragging = true
         pointerMoved = true
         liftedInstanceId = block.event.instanceId
@@ -926,10 +1022,10 @@ class TimelineDragController {
         val event = source?.event ?: return null
         val edge = resize?.edge
         if (edge != null) {
-            val drop = resizedDrop(event, edge, date, startMin, spanMin, zone)
+            val drop = resizedSpan(event, edge, date, startMin, spanMin, zone)
             return event.copy(start = drop.start, end = drop.end)
         }
-        val start = TimelineDrop(event, date, startMin, clipOffsetMin).startInstant(zone)
+        val start = dropStartInstant(event, date, startMin, clipOffsetMin, zone)
         return event.copy(start = start, end = start + dragDuration)
     }
 
@@ -943,9 +1039,8 @@ class TimelineDragController {
         val edge = resize?.edge
         cancel()
         if (landed == null || landed.slot == origin) return null
-        val drop = resizedDrop(landed.event, edge, landed.date, landed.eventStartMin, landed.eventSpanMin, zone)
-        settle(landed, end = drop.end)
-        return drop
+        val span = resizedSpan(landed.event, edge, landed.date, landed.eventStartMin, landed.eventSpanMin, zone)
+        return TimelineResizeDrop(landed.event, span.start, span.end, settle(landed, end = span.end))
     }
 
     /**
@@ -1199,7 +1294,6 @@ fun rememberTimelineDragController(): TimelineDragController {
     controller.geometry.edgePx = with(density) { AUTO_SCROLL_EDGE.toPx() }
     controller.geometry.stepPx = with(density) { AUTO_SCROLL_STEP.toPx() }
     controller.slopPx = LocalViewConfiguration.current.touchSlop
-    controller.abandonedTicks = LocalEventMove.current?.abandoned
     return controller
 }
 
@@ -1229,7 +1323,16 @@ fun TimedBlock.continuesBefore(day: LocalDate, zone: TimeZone): Boolean =
  * visibly settles there.
  */
 fun TimelineDrop.startInstant(zone: TimeZone): Instant =
-    wallClockInstant(date, startMin - clipOffsetMin, zone, kept = zone.repeatedHourOffsetAt(event.start))
+    dropStartInstant(event, date, startMin, clipOffsetMin, zone)
+
+/** Where [event] starts when its block's top edge lands [startMin] past [date]'s midnight — see [TimelineDrop]. */
+internal fun dropStartInstant(
+    event: EventInstance,
+    date: LocalDate,
+    startMin: Int,
+    clipOffsetMin: Int,
+    zone: TimeZone,
+): Instant = wallClockInstant(date, startMin - clipOffsetMin, zone, kept = zone.repeatedHourOffsetAt(event.start))
 
 /**
  * The wall-clock minutes an event lasting [duration] covers when it starts
@@ -1301,6 +1404,7 @@ private const val SETTLE_TIMEOUT_MILLIS = 900L
  */
 const val SETTLE_FADE_MILLIS: Int = 250
 
+
 /**
  * The floating block, drawn over the whole calendar so it is free of the day
  * column's clip and of the scroll viewport's rounded corners.
@@ -1308,12 +1412,10 @@ const val SETTLE_FADE_MILLIS: Int = 250
 @Composable
 fun TimelineDragOverlay(controller: TimelineDragController, modifier: Modifier = Modifier) {
     var origin by remember { mutableStateOf(Offset.Zero) }
-    val density = LocalDensity.current
-    val dark = LocalFloretDarkTheme.current
-    val use24Hour = LocalUse24HourFormat.current
-    val locale = currentLocale()
     val reduceMotion = rememberReduceMotion()
-    val moveInFlight = moveInFlight()
+    val drops = dropStates()
+    val moveInFlight = controller.settledToken in drops.pending
+    val stripInFlight = controller.stripToken in drops.pending
 
     // Both live here rather than beside the controller: they read [drag], which
     // changes every frame, and this composable is the one that is meant to.
@@ -1327,12 +1429,11 @@ fun TimelineDragOverlay(controller: TimelineDragController, modifier: Modifier =
     // recurring drop's scope dialog is up — and then until the grid draws the
     // drop itself.
     var handingOver by remember(controller.settling) { mutableStateOf(false) }
-    val abandoned = abandonedMoves()
+    val abandoned = controller.settledToken in drops.abandoned
     LaunchedEffect(controller.settling, moveInFlight, controller.settledOnGrid, abandoned) {
         if (controller.settling == null || moveInFlight) return@LaunchedEffect
-        // Past the mark this drop was let go on, it was abandoned: nothing will
-        // land and there is nothing to wait for.
-        if (abandoned == controller.settledAbandonedMark) {
+        // An abandoned drop: nothing will land and there is nothing to wait for.
+        if (!abandoned) {
             delay(if (controller.settledOnGrid) SETTLE_GRACE_MILLIS else SETTLE_TIMEOUT_MILLIS)
         }
         handingOver = true
@@ -1342,9 +1443,10 @@ fun TimelineDragOverlay(controller: TimelineDragController, modifier: Modifier =
     }
 
     // The same hold for a bar moved along the all-day strip.
-    LaunchedEffect(controller.stripSettling, moveInFlight, controller.stripSeated, abandoned) {
-        if (controller.stripSettling == null || moveInFlight) return@LaunchedEffect
-        if (abandoned == controller.stripAbandonedMark) {
+    val stripAbandoned = controller.stripToken in drops.abandoned
+    LaunchedEffect(controller.stripSettling, stripInFlight, controller.stripSeated, stripAbandoned) {
+        if (controller.stripSettling == null || stripInFlight) return@LaunchedEffect
+        if (!stripAbandoned) {
             delay(if (controller.stripSeated) SETTLE_GRACE_MILLIS else SETTLE_TIMEOUT_MILLIS)
         }
         controller.releaseStrip()
@@ -1358,6 +1460,12 @@ fun TimelineDragOverlay(controller: TimelineDragController, modifier: Modifier =
             .clearAndSetSemantics { }
             .onGloballyPositioned { origin = it.positionInRoot() },
     ) {
+        controller.held.forEach { parked ->
+            key(parked.token) { HeldTimelineCopy(controller, parked, origin) }
+        }
+        controller.heldStrips.forEach { parked ->
+            key(parked.token) { HeldStripSettle(controller, parked) }
+        }
         val drag = controller.drag ?: controller.settling ?: return@Box
         // Landed: the copy sinks back to the grid's own plane while the write runs.
         val landed = controller.drag == null
@@ -1371,6 +1479,58 @@ fun TimelineDragOverlay(controller: TimelineDragController, modifier: Modifier =
             animationSpec = tween(SETTLE_FADE_MILLIS),
             label = "drag-handover",
         )
+        TimelineCopy(drag, controller.geometry, origin, lift, copyAlpha)
+    }
+}
+
+/**
+ * [TimelineDragController.ghosts] for [block], derived so the block recomposes
+ * only when its own answer changes rather than on every lift, park and release.
+ */
+@Composable
+fun TimelineDragController.ghostsDerived(block: TimedBlock): Boolean {
+    val ghosted by remember(this, block) { derivedStateOf { ghosts(block) } }
+    return ghosted
+}
+
+/** A drop parked by a newer pickup: held at its landing slot until its own write settles. */
+@Composable
+private fun HeldTimelineCopy(controller: TimelineDragController, parked: HeldDrop, origin: Offset) {
+    val alpha = rememberHeldSettle(
+        token = parked.token,
+        seated = parked.seated,
+        timeoutMillis = SETTLE_TIMEOUT_MILLIS,
+        onHandOver = { controller.handOverHeld(parked.token) },
+        onRelease = { controller.releaseHeld(parked.token) },
+    )
+    TimelineCopy(parked.copy, controller.geometry, origin, lift = 0f, copyAlpha = alpha)
+}
+
+/** A strip drop parked by a newer one: shown at its new days until its own write settles. */
+@Composable
+private fun HeldStripSettle(controller: TimelineDragController, parked: HeldStrip) {
+    rememberHeldSettle(
+        token = parked.token,
+        seated = parked.seated,
+        timeoutMillis = SETTLE_TIMEOUT_MILLIS,
+        onHandOver = {},
+        onRelease = { controller.releaseHeldStrip(parked.token) },
+    )
+}
+
+/** [drag]'s pieces drawn over the calendar, clipped to the timeline's viewport. */
+@Composable
+private fun TimelineCopy(
+    drag: TimelineDrag,
+    geometry: TimelineGeometry,
+    origin: Offset,
+    lift: Float,
+    copyAlpha: Float,
+) {
+    val density = LocalDensity.current
+    val dark = LocalFloretDarkTheme.current
+    val use24Hour = LocalUse24HourFormat.current
+    val locale = currentLocale()
         val paint = eventPaint(drag.event, dark)
         val title = drag.event.title.ifBlank { stringResource(R.string.event_untitled) }
         // Read off the event rather than the held block, so grabbing either half
@@ -1386,7 +1546,7 @@ fun TimelineDragOverlay(controller: TimelineDragController, modifier: Modifier =
         // so no column clip or rounded corner cuts it, but it still belongs to
         // the timeline: a piece a whole day tall reaches far past both ends of
         // the viewport, and unclipped it paints over the headers above (#267).
-        val port = controller.geometry.viewport?.takeIf { it.isAttached }?.boundsInRoot()
+        val port = geometry.viewport?.takeIf { it.isAttached }?.boundsInRoot()
         // How much of each piece the viewport actually shows. A multi-day event
         // has a piece per day, and the widest one is a full 24 hours — taller
         // than the screen, its top at a midnight scrolled out of sight. Picking
@@ -1438,7 +1598,6 @@ fun TimelineDragOverlay(controller: TimelineDragController, modifier: Modifier =
                 )
             }
         }
-    }
 }
 
 /** One piece of a dragged block, floating over the calendar. */

app/src/main/java/de/jeanlucmakiola/calendula/ui/month/MonthDrag.kt

@@ -14,8 +14,7 @@ import androidx.compose.ui.layout.boundsInRoot
 import androidx.compose.ui.layout.positionInRoot
 import androidx.compose.ui.unit.IntSize
 import de.jeanlucmakiola.calendula.domain.EventInstance
-import de.jeanlucmakiola.calendula.ui.common.LocalEventMove
-import kotlinx.coroutines.flow.StateFlow
+import de.jeanlucmakiola.calendula.ui.common.nextMoveToken
 import kotlinx.datetime.LocalDate
 import kotlin.math.abs
 
@@ -107,11 +106,22 @@ data class MonthChipDrag(
     val time: String? = null,
 )
 
+/** A drop parked by a newer pickup while its write still runs — see [MonthDragController.held]. */
+data class HeldChip(
+    val copy: MonthChipDrag,
+    val token: Long,
+    val handedOver: Boolean = false,
+    /** Where the grid now draws the drop, in root coordinates, once a row seats it. */
+    val seat: Offset? = null,
+)
+
 /** Where a finished chip drag asks its event to go, as a whole-day shift. */
 data class MonthChipDrop(
     val event: EventInstance,
     val grabDate: LocalDate,
     val targetDate: LocalDate,
+    /** The drop's identity, which its held copy waits on — see [MonthDragController.settledToken]. */
+    val token: Long,
 )
 
 /**
@@ -167,19 +177,22 @@ class MonthDragController {
         private set
 
     /**
-     * The last drop this controller made, kept past [release] for [beginUndo] —
-     * the confirmation chip carries Undo long after the copy is gone.
+     * This controller's recent drops by token, kept past [release] for
+     * [beginUndo] — the confirmation chip carries Undo long after the copy is
+     * gone, and it may be any of them the chip offers to undo.
      */
-    private var undoable: MonthChipDrag? = null
+    private val undoable = LinkedHashMap<Long, MonthChipDrag>()
 
     /**
-     * The abandoned-move counter, read at the drop so the mark can't be a
-     * composition behind the tick it is compared against.
+     * Earlier drops still being written when another chip was picked up. They
+     * keep their copy and their ghost until their own token settles, rather than
+     * vanishing and flashing back on the old day (#494).
      */
-    var abandonedTicks: StateFlow<Int>? = null
+    var held: List<HeldChip> by mutableStateOf(emptyList())
+        private set
 
-    /** What [abandonedTicks] stood at when the settling chip was let go. */
-    var settledAbandonedMark: Int = 0
+    /** The token of the drop (or undo) [settling] is waiting on. */
+    var settledToken: Long = 0L
         private set
 
     private var event: EventInstance? = null
@@ -208,7 +221,7 @@ class MonthDragController {
         this.event = event
         this.grabDate = grabDate
         this.time = time
-        settling = null
+        parkSettling()
         isDragging = true
         liftedInstanceId = event.instanceId
         grab = pointerInRoot - chipInRoot
@@ -234,6 +247,39 @@ class MonthDragController {
         settledGhost = false
     }
 
+    /**
+     * Whether [event]'s chip belongs to a held drop and must stay a ghost: its
+     * source, or once a row seats it, the chip the grid draws on its target day.
+     */
+    fun isHeldChip(event: EventInstance, days: List<LocalDate>?): Boolean = held.any { parked ->
+        !parked.handedOver && (
+            parked.copy.event.instanceId == event.instanceId ||
+                (
+                    parked.seat != null && days != null && parked.copy.targetDate in days &&
+                        isSameEvent(event, parked.copy.event)
+                    )
+            )
+    }
+
+    /** Move a still-settling drop to [held] before a new pickup takes the slot. */
+    private fun parkSettling() {
+        val landed = settling
+        if (landed != null) held = held + HeldChip(landed, settledToken)
+        settling = null
+        settledInRoot = null
+        settledGhost = false
+    }
+
+    /** Stop ghosting the held drop [token]'s source while its copy fades. */
+    fun handOverHeld(token: Long) {
+        held = held.map { if (it.token == token) it.copy(handedOver = true) else it }
+    }
+
+    /** Drop the held copy [token] once it has faded. */
+    fun releaseHeld(token: Long) {
+        held = held.filterNot { it.token == token }
+    }
+
     /**
      * Whether [days] holds the chip the grid has drawn for the settled drop —
      * the seat the copy is on its way to, which must ghost until it gets there.
@@ -250,6 +296,13 @@ class MonthDragController {
      * nearest where the chip was let go is the one the finger was over.
      */
     fun noteSettled(token: Any) {
+        val row = rows[token]
+        if (row != null && held.any { it.seat == null }) {
+            held = held.map { parked ->
+                val target = parked.copy.targetDate
+                if (parked.seat != null || target == null) parked else parked.copy(seat = row.seatOf(parked.copy.event, target))
+            }
+        }
         val landed = settling ?: return
         val target = landed.targetDate ?: return
         val at = rows[token]?.seatOf(landed.event, target) ?: return
@@ -265,16 +318,16 @@ class MonthDragController {
      * there is no drop of this controller's left to undo, or the grid doesn't
      * seat the moved event where the chip would have to start from.
      */
-    fun beginUndo(): Boolean {
-        val last = undoable ?: return false
-        undoable = null
+    fun beginUndo(token: Long, dropToken: Long): Boolean {
+        val last = undoable.remove(dropToken) ?: return false
+        parkSettling()
         val from = last.targetDate ?: return false
         val at = rows.values.firstNotNullOfOrNull { it.seatOf(last.event, from) } ?: return false
         settling = last.copy(grabDate = from, targetDate = last.grabDate, topLeftInRoot = at)
         liftedInstanceId = last.event.instanceId
         settledGhost = true
         settledInRoot = null
-        settledAbandonedMark = abandonedTicks?.value ?: 0
+        settledToken = token
         return true
     }
 
@@ -294,10 +347,11 @@ class MonthDragController {
         )
         liftedInstanceId = landed.event.instanceId
         settledGhost = true
-        undoable = settling
-        settledAbandonedMark = abandonedTicks?.value ?: 0
+        settledToken = nextMoveToken()
+        undoable[settledToken] = requireNotNull(settling)
+        if (undoable.size > UNDOABLE_KEPT) undoable.remove(undoable.keys.first())
         drops++
-        return MonthChipDrop(landed.event, landed.grabDate, target)
+        return MonthChipDrop(landed.event, landed.grabDate, target, settledToken)
     }
 
     /**
@@ -355,9 +409,10 @@ class MonthDragController {
 
 @Composable
 fun rememberMonthDragController(): MonthDragController {
-    val controller = remember { MonthDragController() }
-    controller.abandonedTicks = LocalEventMove.current?.abandoned
-    return controller
+    return remember { MonthDragController() }
 }
 
 val LocalMonthDrag = compositionLocalOf<MonthDragController?> { null }
+
+/** How many recent drops a month controller keeps for an undo to carry back. */
+private const val UNDOABLE_KEPT = 8

app/src/main/java/de/jeanlucmakiola/calendula/ui/month/MonthScreen.kt

@@ -125,11 +125,11 @@ import de.jeanlucmakiola.calendula.ui.common.eventTitleOverflow
 import de.jeanlucmakiola.calendula.ui.common.MoveTarget
 import de.jeanlucmakiola.calendula.ui.common.MoveRequest
 import de.jeanlucmakiola.calendula.ui.common.LocalEventMove
-import de.jeanlucmakiola.calendula.ui.common.moveInFlight
-import de.jeanlucmakiola.calendula.ui.common.abandonedMoves
+import de.jeanlucmakiola.calendula.ui.common.dropStates
 import de.jeanlucmakiola.calendula.ui.common.OnUndoStarted
 import de.jeanlucmakiola.calendula.ui.common.ghostAlpha
 import de.jeanlucmakiola.calendula.ui.common.DragSnapHaptics
+import de.jeanlucmakiola.calendula.ui.common.rememberHeldSettle
 import de.jeanlucmakiola.calendula.ui.common.SETTLE_FADE_MILLIS
 import de.jeanlucmakiola.calendula.ui.common.SETTLE_GRACE_MILLIS
 import de.jeanlucmakiola.calendula.ui.common.EventMoveScope
@@ -515,7 +515,7 @@ fun MonthScreen(
         val chipDrag = rememberMonthDragController()
         // Undo moves the event back, so the chip travels back too. The
         // signal comes from the write, not from the chip that offers it.
-        OnUndoStarted { chipDrag.beginUndo() }
+        OnUndoStarted { start -> chipDrag.beginUndo(start.token, start.dropToken) }
         Box(
             modifier = Modifier
                 .padding(innerPadding)
@@ -591,11 +591,11 @@ private const val MONTH_SETTLE_TIMEOUT_MILLIS = 450L
 @Composable
 private fun MonthDragOverlay(controller: MonthDragController, showStartTimes: Boolean) {
     var origin by remember { mutableStateOf(Offset.Zero) }
-    val dark = LocalFloretDarkTheme.current
-    val density = LocalDensity.current
     val timeFit = rememberMonthChipTimeFit(showStartTimes)
     val reduceMotion = rememberReduceMotion()
-    val moveInFlight = moveInFlight()
+    val drops = dropStates()
+    val moveInFlight = controller.settledToken in drops.pending
+    val abandoned = controller.settledToken in drops.abandoned
     // Here rather than beside the controller: this reads [drag], which changes
     // every frame, and this composable is the one that is meant to.
     DragSnapHaptics(controller.drag?.targetDate, controller.drops)
@@ -608,14 +608,12 @@ private fun MonthDragOverlay(controller: MonthDragController, showStartTimes: Bo
     val glide = remember { Animatable(Offset.Zero, Offset.VectorConverter) }
     val glideSpec = MaterialTheme.motionScheme.fastSpatialSpec<Offset>()
     val seat = controller.settledInRoot
-    val abandoned = abandonedMoves()
     LaunchedEffect(controller.settling, moveInFlight, seat, abandoned) {
         val landed = controller.settling
         if (landed == null || moveInFlight) return@LaunchedEffect
         if (seat == null) {
-            // Past the mark this drop was let go on, it was abandoned and no
-            // seat is ever coming.
-            if (abandoned == controller.settledAbandonedMark) delay(MONTH_SETTLE_TIMEOUT_MILLIS)
+            // An abandoned drop has no seat coming.
+            if (!abandoned) delay(MONTH_SETTLE_TIMEOUT_MILLIS)
         } else {
             if (!gliding) glide.snapTo(landed.topLeftInRoot)
             gliding = true
@@ -635,6 +633,9 @@ private fun MonthDragOverlay(controller: MonthDragController, showStartTimes: Bo
             .clearAndSetSemantics { }
             .onGloballyPositioned { origin = it.positionInRoot() },
     ) {
+        controller.held.forEach { parked ->
+            key(parked.token) { HeldMonthChip(controller, parked, origin, timeFit) }
+        }
         val drag = controller.drag ?: controller.settling ?: return@Box
         // Landed: the copy sinks back to the grid's own plane while the write runs.
         val lift by animateFloatAsState(
@@ -646,42 +647,93 @@ private fun MonthDragOverlay(controller: MonthDragController, showStartTimes: Bo
             animationSpec = tween(SETTLE_FADE_MILLIS),
             label = "chip-handover",
         )
-        MonthBar(
-            event = drag.event,
-            dark = dark,
-            continuesLeft = false,
-            continuesRight = false,
-            // The time the source chip carried, drawn only if this one-column
-            // cut-out of it has the room — which a slice of a multi-day bar has
-            // not, however wide the bar was.
-            time = drag.time,
+        MonthChipCopy(
+            drag = drag,
+            // Read at layout, so the glide doesn't recompose every frame.
+            at = { if (gliding) glide.value else drag.topLeftInRoot },
+            origin = origin,
+            lift = lift,
+            alpha = copyAlpha,
             timeFit = timeFit,
-            chipWidth = with(density) { drag.sizePx.width.toDp() },
-            modifier = Modifier
-                // Absolute: these are root coordinates, and the direction-aware
-                // offset would mirror them across the screen in an RTL layout.
-                .absoluteOffset {
-                    val at = if (gliding) glide.value else drag.topLeftInRoot
-                    IntOffset(
-                        (at.x - origin.x).roundToInt(),
-                        (at.y - origin.y).roundToInt(),
-                    )
-                }
-                .width(with(density) { drag.sizePx.width.toDp() })
-                .height(with(density) { drag.sizePx.height.toDp() })
-                .padding(horizontal = MONTH_CHIP_INSET, vertical = 1.dp)
-                .graphicsLayer {
-                    scaleX = 1f + 0.04f * lift
-                    scaleY = 1f + 0.04f * lift
-                    shadowElevation = 8.dp.toPx() * lift
-                    alpha = copyAlpha
-                    shape = EventChipShape
-                    clip = false
-                },
         )
     }
 }
 
+/** A drop parked by a newer pickup: held on its landing day until its own write settles. */
+@Composable
+private fun HeldMonthChip(
+    controller: MonthDragController,
+    parked: HeldChip,
+    origin: Offset,
+    timeFit: MonthChipTimeFit?,
+) {
+    val reduceMotion = rememberReduceMotion()
+    val glide = remember { Animatable(parked.copy.topLeftInRoot, Offset.VectorConverter) }
+    val glideSpec = MaterialTheme.motionScheme.fastSpatialSpec<Offset>()
+    val seat = parked.seat
+    val landed = parked.token !in dropStates().pending
+    // Carried onto its seat once the write is in, as the settling chip is.
+    LaunchedEffect(seat, landed) {
+        if (seat == null || !landed) return@LaunchedEffect
+        if (reduceMotion) glide.snapTo(seat) else glide.animateTo(seat, glideSpec)
+    }
+    val alpha = rememberHeldSettle(
+        token = parked.token,
+        seated = seat != null,
+        timeoutMillis = MONTH_SETTLE_TIMEOUT_MILLIS,
+        onHandOver = { controller.handOverHeld(parked.token) },
+        onRelease = { controller.releaseHeld(parked.token) },
+    )
+    MonthChipCopy(parked.copy, { glide.value }, origin, lift = 0f, alpha = alpha, timeFit = timeFit)
+}
+
+/** [drag]'s chip floating over the grid with its top left at [at], in root coordinates. */
+@Composable
+private fun MonthChipCopy(
+    drag: MonthChipDrag,
+    at: () -> Offset,
+    origin: Offset,
+    lift: Float,
+    alpha: Float,
+    timeFit: MonthChipTimeFit?,
+) {
+    val density = LocalDensity.current
+    val dark = LocalFloretDarkTheme.current
+    MonthBar(
+        event = drag.event,
+        dark = dark,
+        continuesLeft = false,
+        continuesRight = false,
+        // The time the source chip carried, drawn only if this one-column
+        // cut-out of it has the room — which a slice of a multi-day bar has
+        // not, however wide the bar was.
+        time = drag.time,
+        timeFit = timeFit,
+        chipWidth = with(density) { drag.sizePx.width.toDp() },
+        modifier = Modifier
+            // Absolute: these are root coordinates, and the direction-aware
+            // offset would mirror them across the screen in an RTL layout.
+            .absoluteOffset {
+                val topLeft = at()
+                IntOffset(
+                    (topLeft.x - origin.x).roundToInt(),
+                    (topLeft.y - origin.y).roundToInt(),
+                )
+            }
+            .width(with(density) { drag.sizePx.width.toDp() })
+            .height(with(density) { drag.sizePx.height.toDp() })
+            .padding(horizontal = MONTH_CHIP_INSET, vertical = 1.dp)
+            .graphicsLayer {
+                scaleX = 1f + 0.04f * lift
+                scaleY = 1f + 0.04f * lift
+                shadowElevation = 8.dp.toPx() * lift
+                this.alpha = alpha
+                shape = EventChipShape
+                clip = false
+            },
+    )
+}
+
 /**
  * Content for both scrolling styles. No swipe detector and no [AnimatedContent]:
  * vertical scrolling owns the gesture, and the list never swaps wholesale — it
@@ -2258,7 +2310,7 @@ private fun MonthWeekRow(
     // Once the grid holds the settled chip, tell the controller where this row
     // has seated it, so the copy in flight can glide onto it. Keyed on the week,
     // which is what changes when the re-read lands.
-    LaunchedEffect(week, dragController?.settling) {
+    LaunchedEffect(week, dragController?.settling, dragController?.held) {
         dragController?.noteSettled(rowToken)
     }
 
@@ -2691,6 +2743,8 @@ private fun monthChipDragModifier(
                     beginMillis = drop.event.start.toEpochMilliseconds(),
                     endMillis = drop.event.end.toEpochMilliseconds(),
                     target = MoveTarget.ByDays(delta),
+                    isAllDay = drop.event.isAllDay,
+                    token = drop.token,
                 ),
             )
         }
@@ -2836,8 +2890,17 @@ private fun MonthBar(
     val moveAction = eventMoveAction(event)
     // The source stays put as a ghost while its floating copy travels.
     val monthDrag = LocalMonthDrag.current
-    val lifted = monthDrag?.liftedInstanceId == event.instanceId ||
-        monthDrag?.isSettledChip(event, days) == true
+    // Derived, so a chip recomposes only when its own answer changes rather than
+    // on every lift, park and release anywhere in the grid.
+    val lifted by remember(monthDrag, event, days) {
+        derivedStateOf {
+            monthDrag != null && (
+                monthDrag.liftedInstanceId == event.instanceId ||
+                    monthDrag.isSettledChip(event, days) ||
+                    monthDrag.isHeldChip(event, days)
+                )
+        }
+    }
     val ghost = ghostAlpha(lifted)
     val shape = monthBarShape(continuesLeft, continuesRight)
     Box(

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

@@ -6,22 +6,35 @@ import android.content.Intent
 import android.os.Build
 import android.os.PowerManager
 import android.provider.Settings
+import android.provider.Settings.System.DEFAULT_NOTIFICATION_URI
+import android.widget.Toast
 import androidx.activity.compose.rememberLauncherForActivityResult
 import androidx.activity.result.contract.ActivityResultContracts
 import androidx.compose.animation.AnimatedVisibility
+import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
 import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.height
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.automirrored.filled.KeyboardArrowRight
+import androidx.compose.material.icons.automirrored.filled.OpenInNew
+import androidx.compose.material.icons.outlined.Info
 import androidx.compose.material3.Icon
 import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Text
+import androidx.compose.material3.TextButton
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.DisposableEffect
+import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
+import androidx.compose.runtime.rememberCoroutineScope
+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.LocalContext
 import androidx.compose.ui.res.stringResource
@@ -29,8 +42,11 @@ import androidx.compose.ui.unit.dp
 import androidx.core.net.toUri
 import androidx.lifecycle.Lifecycle
 import androidx.lifecycle.LifecycleEventObserver
+import androidx.lifecycle.compose.LifecycleResumeEffect
 import androidx.lifecycle.compose.LocalLifecycleOwner
+import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import de.jeanlucmakiola.calendula.R
+import de.jeanlucmakiola.calendula.domain.CalendarSource
 import de.jeanlucmakiola.calendula.ui.common.CalendarColorChip
 import de.jeanlucmakiola.calendula.ui.common.DurationPicker
 import de.jeanlucmakiola.calendula.ui.common.REMINDER_PRESETS
@@ -39,10 +55,14 @@ import de.jeanlucmakiola.calendula.ui.common.TimePickerAlert
 import de.jeanlucmakiola.calendula.ui.common.durationLabel
 import de.jeanlucmakiola.calendula.ui.common.orUnnamed
 import de.jeanlucmakiola.floret.android.hasPermission
+import de.jeanlucmakiola.floret.android.notificationSoundPickerIntent
+import de.jeanlucmakiola.floret.android.openNotificationSettings
+import de.jeanlucmakiola.floret.android.pickedSound
 import de.jeanlucmakiola.floret.components.CollapsingScaffold
 import de.jeanlucmakiola.floret.components.ExpandIcon
 import de.jeanlucmakiola.floret.components.GroupedRow
 import de.jeanlucmakiola.floret.components.GroupedSwitchRow
+import de.jeanlucmakiola.floret.components.IconInfoCard
 import de.jeanlucmakiola.floret.components.Position
 import de.jeanlucmakiola.floret.components.SelectedCheck
 import de.jeanlucmakiola.floret.identity.collapseExit
@@ -50,6 +70,7 @@ import de.jeanlucmakiola.floret.identity.expandEnter
 import de.jeanlucmakiola.floret.reminders.ReminderOverride
 import de.jeanlucmakiola.floret.reminders.minutesOrEmpty
 import de.jeanlucmakiola.floret.reminders.reminderOverrideFor
+import kotlinx.coroutines.launch
 import kotlinx.datetime.LocalTime
 
 /**
@@ -86,6 +107,63 @@ internal fun NotificationsScreen(
     var overrideDialog by remember { mutableStateOf<OverrideTarget?>(null) }
     var calendarSectionExpanded by remember { mutableStateOf(false) }
     var expandedCalendars by remember { mutableStateOf(emptySet<Long>()) }
+    val scope = rememberCoroutineScope()
+    val channelStatus by viewModel.channelStatus.collectAsStateWithLifecycle()
+    val calendarIds = state.reminderCalendars.map { it.id }
+    LifecycleResumeEffect(calendarIds) {
+        viewModel.refreshChannelStatus(calendarIds)
+        onPauseOrDispose { }
+    }
+    val openCalendarSettings: (Long) -> Unit = { calendarId ->
+        scope.launch { context.openNotificationSettings(viewModel.soundSettingsChannel(calendarId)) }
+    }
+    val openAppSettings: () -> Unit = {
+        scope.launch {
+            viewModel.syncReminderChannels()
+            context.openNotificationSettings()
+        }
+    }
+    val loadedSounds by viewModel.channelSounds.collectAsStateWithLifecycle()
+    val sounds = loadedSounds.orEmpty()
+    val soundFailedMessage = stringResource(R.string.settings_notification_sound_failed)
+    val soundUnreadableMessage = stringResource(R.string.settings_notification_sound_unreadable)
+    LaunchedEffect(Unit) {
+        viewModel.soundFailed.collect { failure ->
+            val message = if (failure == SoundFailure.Unreadable) soundUnreadableMessage else soundFailedMessage
+            Toast.makeText(context, message, Toast.LENGTH_LONG).show()
+        }
+    }
+    // ALL_CALENDARS, a calendar id, or null when no pick is pending.
+    var soundTarget by rememberSaveable { mutableStateOf<Long?>(null) }
+    val soundPicker = rememberLauncherForActivityResult(ActivityResultContracts.StartActivityForResult()) { result ->
+        val target = soundTarget
+        soundTarget = null
+        val picked = pickedSound(result.resultCode, result.data) ?: return@rememberLauncherForActivityResult
+        when (target) {
+            null -> Unit
+            ALL_CALENDARS -> viewModel.setReminderSoundForAll(picked.uri)
+            else -> viewModel.setReminderSound(target, picked.uri)
+        }
+    }
+    val pickSoundTitle = stringResource(R.string.settings_notification_sound)
+    val pickSound: (Long) -> Unit = pick@{ target ->
+        if (soundTarget != null) return@pick
+        val current = if (target == ALL_CALENDARS) {
+            (sharedSound(sounds, calendarIds) as? SharedSound.Same)?.sound
+        } else {
+            sounds[target]
+        }
+        soundTarget = target
+        try {
+            // A missing or mixed sound preselects Default; a silent one, Silent.
+            val preselect = if (current == null) DEFAULT_NOTIFICATION_URI else current.uri
+            soundPicker.launch(notificationSoundPickerIntent(preselect, pickSoundTitle))
+        } catch (e: RuntimeException) {
+            // No picker, or one that refuses to start: the system screen still has the sound.
+            soundTarget = null
+            if (target == ALL_CALENDARS) openAppSettings() else openCalendarSettings(target)
+        }
+    }
 
     CollapsingScaffold(
         title = stringResource(R.string.settings_section_notifications),
@@ -93,6 +171,16 @@ internal fun NotificationsScreen(
         predictiveBack = true,
         visible = visible,
     ) {
+        if (IS_SAMSUNG && !state.notificationCategoryHintDismissed) {
+            NotificationCategoryHint(
+                onOpen = {
+                    viewModel.dismissNotificationCategoryHint()
+                    openAppSettings()
+                },
+                onDismiss = viewModel::dismissNotificationCategoryHint,
+            )
+            Spacer(Modifier.height(16.dp))
+        }
         GroupedSwitchRow(
             title = stringResource(R.string.settings_reminders),
             checked = state.remindersEnabled,
@@ -100,6 +188,25 @@ internal fun NotificationsScreen(
             summary = stringResource(R.string.settings_reminders_hint),
             position = Position.Top,
         )
+        if (calendarIds.isNotEmpty()) {
+            GroupedRow(
+                title = stringResource(R.string.settings_notification_sound),
+                summary = loadedSounds?.let { globalSoundLabel(it, calendarIds) },
+                position = Position.Middle,
+                onClick = { pickSound(ALL_CALENDARS) },
+            )
+        }
+        GroupedRow(
+            title = stringResource(R.string.settings_notification_more),
+            summary = if (channelStatus.appBlocked) {
+                stringResource(R.string.settings_notifications_blocked_hint)
+            } else {
+                stringResource(R.string.settings_notification_sound_hint)
+            },
+            position = Position.Middle,
+            trailing = { ExternalLinkIcon() },
+            onClick = openAppSettings,
+        )
         GroupedRow(
             title = stringResource(R.string.settings_default_reminder),
             summary = reminderChoiceLabel(state.defaultReminderMinutes),
@@ -149,10 +256,8 @@ internal fun NotificationsScreen(
             onClick = { showSnooze = true },
         )
 
-        // Per-calendar overrides, folded behind one header. Each writable
-        // calendar may keep, drop or replace the global default, separately for
-        // timed and all-day events.
-        if (state.writableCalendars.isNotEmpty()) {
+        // Per-calendar notifications and reminder overrides (#145, #272).
+        if (state.reminderCalendars.isNotEmpty()) {
             Spacer(Modifier.height(24.dp))
             GroupedRow(
                 title = stringResource(R.string.settings_calendar_reminders_title),
@@ -167,30 +272,18 @@ internal fun NotificationsScreen(
                 exit = collapseExit(),
             ) {
                 Column {
-                    state.writableCalendars.forEach { calendar ->
+                    state.reminderCalendars.forEach { calendar ->
                         Spacer(Modifier.height(16.dp))
-                        // Special-dates calendars own their reminders in their
-                        // own section — link there instead.
-                        if (calendar.id in state.managedCalendarIds) {
-                            GroupedRow(
-                                title = calendar.displayName.orUnnamed(),
-                                summary = stringResource(R.string.settings_calendar_reminders_managed_hint),
-                                position = Position.Alone,
-                                leading = { CalendarColorChip(calendar.color) },
-                                trailing = {
-                                    Icon(
-                                        imageVector = Icons.AutoMirrored.Filled.KeyboardArrowRight,
-                                        contentDescription = null,
-                                        tint = MaterialTheme.colorScheme.onSurfaceVariant,
-                                    )
-                                },
-                                onClick = onOpenSpecialDates,
-                            )
-                            return@forEach
-                        }
                         val expanded = calendar.id in expandedCalendars
+                        val notifying = calendar.id !in state.mutedReminderCalendarIds
+                        val blocked = notifying && calendar.id in channelStatus.blockedCalendarIds
                         GroupedRow(
                             title = calendar.displayName.orUnnamed(),
+                            summary = when {
+                                !notifying -> stringResource(R.string.settings_calendar_notifications_off)
+                                blocked -> stringResource(R.string.settings_notifications_blocked)
+                                else -> null
+                            },
                             position = if (expanded) Position.Top else Position.Alone,
                             leading = { CalendarColorChip(calendar.color) },
                             trailing = { ExpandIcon(expanded) },
@@ -207,22 +300,18 @@ internal fun NotificationsScreen(
                             enter = expandEnter(),
                             exit = collapseExit(),
                         ) {
-                            Column {
-                                val timed = state.perCalendarReminderOverride.reminderOverrideFor(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.reminderOverrideFor(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) },
-                                )
-                            }
+                            CalendarNotificationRows(
+                                calendar = calendar,
+                                state = state,
+                                notifying = notifying,
+                                blocked = blocked,
+                                soundLabel = loadedSounds?.let { soundLabel(it[calendar.id]) },
+                                onSetNotifying = { viewModel.setCalendarRemindersEnabled(calendar.id, it) },
+                                onPickSound = { pickSound(calendar.id) },
+                                onOpenSettings = { openCalendarSettings(calendar.id) },
+                                onOpenSpecialDates = onOpenSpecialDates,
+                                onEditOverride = { overrideDialog = it },
+                            )
                         }
                     }
                 }
@@ -309,6 +398,152 @@ internal fun NotificationsScreen(
     }
 }
 
+/**
+ * One calendar's expanded rows: its notification switch and channel deep-link
+ * for every calendar, then the default-reminder overrides where it takes them —
+ * or, for a special-dates calendar, a link to the section that owns them.
+ */
+@Composable
+private fun CalendarNotificationRows(
+    calendar: CalendarSource,
+    state: SettingsUiState,
+    notifying: Boolean,
+    blocked: Boolean,
+    soundLabel: String?,
+    onSetNotifying: (Boolean) -> Unit,
+    onPickSound: () -> Unit,
+    onOpenSettings: () -> Unit,
+    onOpenSpecialDates: () -> Unit,
+    onEditOverride: (OverrideTarget) -> Unit,
+) {
+    val managed = calendar.id in state.managedCalendarIds
+    val takesOverrides = calendar.canModifyContents && !managed
+    Column {
+        GroupedSwitchRow(
+            title = stringResource(R.string.settings_calendar_notifications),
+            checked = notifying,
+            onCheckedChange = onSetNotifying,
+            summary = stringResource(R.string.settings_calendar_notifications_hint),
+            position = Position.Middle,
+        )
+        GroupedRow(
+            title = stringResource(R.string.settings_notification_sound),
+            summary = soundLabel,
+            position = Position.Middle,
+            onClick = onPickSound,
+        )
+        GroupedRow(
+            title = stringResource(R.string.settings_notification_more),
+            summary = if (blocked) {
+                stringResource(R.string.settings_notifications_blocked_hint)
+            } else {
+                stringResource(R.string.settings_calendar_notification_sound_hint)
+            },
+            position = if (managed || takesOverrides) Position.Middle else Position.Bottom,
+            trailing = { ExternalLinkIcon() },
+            onClick = onOpenSettings,
+        )
+        if (managed) {
+            GroupedRow(
+                title = stringResource(R.string.settings_default_reminder_allday),
+                summary = stringResource(R.string.settings_calendar_reminders_managed_hint),
+                position = Position.Bottom,
+                trailing = {
+                    Icon(
+                        imageVector = Icons.AutoMirrored.Filled.KeyboardArrowRight,
+                        contentDescription = null,
+                        tint = MaterialTheme.colorScheme.onSurfaceVariant,
+                    )
+                },
+                onClick = onOpenSpecialDates,
+            )
+        } else if (takesOverrides) {
+            val timed = state.perCalendarReminderOverride.reminderOverrideFor(calendar.id)
+            GroupedRow(
+                title = stringResource(R.string.settings_default_reminder),
+                summary = calendarOverrideSummary(timed, state.defaultReminderMinutes),
+                position = Position.Middle,
+                onClick = { onEditOverride(OverrideTarget(calendar.id, isAllDay = false)) },
+            )
+            val allDay = state.perCalendarAllDayReminderOverride.reminderOverrideFor(calendar.id)
+            GroupedRow(
+                title = stringResource(R.string.settings_default_reminder_allday),
+                summary = calendarOverrideSummary(allDay, state.defaultAllDayReminderMinutes),
+                position = Position.Bottom,
+                onClick = { onEditOverride(OverrideTarget(calendar.id, isAllDay = true)) },
+            )
+        }
+    }
+}
+
+/** [soundTarget] meaning every calendar at once. */
+private const val ALL_CALENDARS = Long.MIN_VALUE
+
+/** What the calendars that have a channel share, sound-wise. */
+private sealed interface SharedSound {
+    data object None : SharedSound
+    data object Mixed : SharedSound
+    data class Same(val sound: ReminderSound) : SharedSound
+}
+
+private fun sharedSound(sounds: Map<Long, ReminderSound>, calendarIds: List<Long>): SharedSound {
+    val distinct = calendarIds.mapNotNull { sounds[it] }.distinctBy { it.uri }
+    return when (distinct.size) {
+        0 -> SharedSound.None
+        1 -> SharedSound.Same(distinct.single())
+        else -> SharedSound.Mixed
+    }
+}
+
+@Composable
+private fun soundLabel(sound: ReminderSound?): String = when {
+    sound == null -> stringResource(R.string.settings_notification_sound_default)
+    sound.uri == null -> stringResource(R.string.settings_notification_sound_silent)
+    sound.uri == DEFAULT_NOTIFICATION_URI -> sound.title
+        ?.let { stringResource(R.string.settings_notification_sound_default_named, it) }
+        ?: stringResource(R.string.settings_notification_sound_default)
+    else -> sound.title ?: stringResource(R.string.settings_notification_sound_custom)
+}
+
+@Composable
+private fun globalSoundLabel(sounds: Map<Long, ReminderSound>, calendarIds: List<Long>): String =
+    when (val shared = sharedSound(sounds, calendarIds)) {
+        SharedSound.None -> soundLabel(null)
+        SharedSound.Mixed -> stringResource(R.string.settings_notification_sound_mixed)
+        is SharedSound.Same -> soundLabel(shared.sound)
+    }
+
+/** Samsung's One UI can start a new notification category switched off (#145). */
+private val IS_SAMSUNG = Build.MANUFACTURER.equals("samsung", ignoreCase = true)
+
+/** The one-time Samsung note, with a way into the app's notification settings. */
+@Composable
+private fun NotificationCategoryHint(onOpen: () -> Unit, onDismiss: () -> Unit) {
+    IconInfoCard(
+        icon = Icons.Outlined.Info,
+        iconContentDescription = null,
+        iconAlignment = Alignment.Top,
+    ) {
+        Text(
+            text = stringResource(R.string.settings_notification_category_hint),
+            style = MaterialTheme.typography.bodyMedium,
+        )
+        Row(Modifier.fillMaxWidth(), horizontalArrangement = Arrangement.End) {
+            TextButton(onClick = onDismiss) { Text(stringResource(R.string.reminder_action_dismiss)) }
+            TextButton(onClick = onOpen) { Text(stringResource(R.string.settings_notification_category_hint_open)) }
+        }
+    }
+}
+
+@Composable
+private fun ExternalLinkIcon() {
+    Icon(
+        imageVector = Icons.AutoMirrored.Filled.OpenInNew,
+        contentDescription = null,
+        tint = MaterialTheme.colorScheme.onSurfaceVariant,
+    )
+}
+
 /** Which calendar + event kind a per-calendar reminder-override dialog targets. */
 private data class OverrideTarget(val calendarId: Long, val isAllDay: Boolean)
 

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

@@ -1,5 +1,6 @@
 package de.jeanlucmakiola.calendula.ui.settings
 
+import android.net.Uri
 import de.jeanlucmakiola.floret.reminders.ReminderOverride
 import de.jeanlucmakiola.calendula.data.prefs.PastEventDisplay
 import de.jeanlucmakiola.calendula.data.prefs.SettingsPrefs
@@ -96,8 +97,14 @@ data class SettingsUiState(
     val perCalendarReminderOverride: Map<Long, List<Int>> = emptyMap(),
     /** Per-calendar overrides of [defaultAllDayReminderMinutes] for all-day events. */
     val perCalendarAllDayReminderOverride: Map<Long, List<Int>> = emptyMap(),
-    /** Writable calendars, shown as per-calendar reminder-override rows. */
+    /** Switched-on calendars you can edit: the per-calendar event-duration rows. */
     val writableCalendars: List<CalendarSource> = emptyList(),
+    /** Switched-on calendars, each with its own notification switch and channel (#145, #272). */
+    val reminderCalendars: List<CalendarSource> = emptyList(),
+    /** Calendars whose reminders Calendula doesn't post (#272). */
+    val mutedReminderCalendarIds: Set<Long> = emptySet(),
+    /** Whether the Samsung notification-category hint has been dismissed (#145); hidden until prefs load. */
+    val notificationCategoryHintDismissed: Boolean = true,
     /**
      * Whether the event-colour picker is offered on calendars that publish no
      * colour palette (the colour may then not survive their next sync).
@@ -130,3 +137,9 @@ data class SpecialDatesUiState(
     /** Epoch millis of the last sync, or 0 if it has never run. */
     val lastRun: Long = 0L,
 )
+
+/** A reminder channel's sound: null [uri] is silent; [title] is null when it can't be resolved. */
+data class ReminderSound(val uri: Uri?, val title: String?)
+
+/** Why a picked reminder sound wasn't applied. */
+enum class SoundFailure { NotApplied, Unreadable }

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

@@ -3,6 +3,8 @@ package de.jeanlucmakiola.calendula.ui.settings
 import android.content.Context
 import android.net.Uri
 import android.os.Build
+import android.provider.Settings
+import android.util.Log
 import androidx.datastore.preferences.core.Preferences
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
@@ -16,10 +18,12 @@ import de.jeanlucmakiola.calendula.data.contacts.SpecialDatesScheduler
 import de.jeanlucmakiola.calendula.data.contacts.SpecialDatesSyncEngine
 import de.jeanlucmakiola.calendula.data.contacts.resolveTitleTemplate
 import de.jeanlucmakiola.calendula.data.fonts.CustomFontStore
+import de.jeanlucmakiola.floret.android.ringtoneTitle
 import de.jeanlucmakiola.floret.android.stateWhileSubscribed
 import de.jeanlucmakiola.floret.di.IoDispatcher
 import de.jeanlucmakiola.floret.reminders.ReminderOverride
 import de.jeanlucmakiola.floret.reminders.reminderOverrideFor
+import de.jeanlucmakiola.calendula.data.prefs.CalendarPrefs
 import de.jeanlucmakiola.calendula.data.prefs.PastEventDisplay
 import de.jeanlucmakiola.calendula.data.prefs.SettingsKeys
 import de.jeanlucmakiola.calendula.data.prefs.SettingsPrefs
@@ -33,6 +37,8 @@ import de.jeanlucmakiola.calendula.data.prefs.SpecialDatesStalledReason
 import de.jeanlucmakiola.floret.prefs.ThemeMode
 import de.jeanlucmakiola.calendula.data.prefs.TimeFormatPref
 import de.jeanlucmakiola.calendula.data.prefs.WeekStartPref
+import de.jeanlucmakiola.calendula.data.reminders.ReminderChannelStatus
+import de.jeanlucmakiola.calendula.data.reminders.ReminderChannels
 import de.jeanlucmakiola.calendula.data.reminders.ReminderScanner
 import de.jeanlucmakiola.calendula.domain.CalendarSource
 import de.jeanlucmakiola.calendula.domain.EventFormField
@@ -45,7 +51,12 @@ import de.jeanlucmakiola.calendula.ui.common.TimelineScale
 import de.jeanlucmakiola.calendula.ui.month.MonthViewStyle
 import de.jeanlucmakiola.calendula.ui.theme.AppFontSettings
 import de.jeanlucmakiola.calendula.ui.theme.FONT_CUSTOM_TOKEN
+import kotlinx.coroutines.CancellationException
 import kotlinx.coroutines.CoroutineDispatcher
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.NonCancellable
+import kotlinx.coroutines.channels.Channel
+import kotlinx.coroutines.flow.receiveAsFlow
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.MutableSharedFlow
 import kotlinx.coroutines.flow.MutableStateFlow
@@ -54,6 +65,7 @@ import kotlinx.coroutines.flow.asStateFlow
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.catch
 import kotlinx.coroutines.flow.combine
+import kotlinx.coroutines.flow.first
 import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
@@ -62,11 +74,13 @@ import javax.inject.Inject
 @HiltViewModel
 class SettingsViewModel @Inject constructor(
     private val prefs: SettingsPrefs,
+    calendarPrefs: CalendarPrefs,
     repository: CalendarRepository,
     private val specialDatesEngine: SpecialDatesSyncEngine,
     specialDatesSpec: SpecialDatesCalendarSpec,
     private val launcherNameManager: LauncherNameManager,
     private val reminderScanner: ReminderScanner,
+    private val reminderChannels: ReminderChannels,
     @IoDispatcher private val io: CoroutineDispatcher,
     @ApplicationContext private val appContext: Context,
 ) : ViewModel() {
@@ -74,16 +88,16 @@ class SettingsViewModel @Inject constructor(
     private val dynamicColorAvailable = Build.VERSION.SDK_INT >= Build.VERSION_CODES.S
 
     /**
-     * Writable calendars that are switched on — the only ones that take a
-     * per-calendar reminder override, since a switched-off one plans no
-     * reminders at all (#75).
+     * Calendars that are switched on — the only ones that plan reminders at
+     * all (#75), so the only ones with notification settings.
      */
-    private val writableCalendars: Flow<List<CalendarSource>> = repository.calendars()
-        .map { calendars -> calendars.filter { it.canModifyContents && it.isVisibleInSystem } }
-        .catch { emit(emptyList()) }
+    private val visibleCalendars: Flow<List<CalendarSource>> =
+        combine(repository.calendars(), calendarPrefs.pendingDisabledCalendarIds) { calendars, pending ->
+            calendars.filter { it.isVisibleInSystem && it.id !in pending }
+        }.catch { emit(emptyList()) }
 
     val state: StateFlow<SettingsUiState> =
-        combine(prefs.data, writableCalendars) { stored, calendars -> stored.toUiState(calendars) }
+        combine(prefs.data, visibleCalendars) { stored, calendars -> stored.toUiState(calendars) }
             .stateWhileSubscribed(
                 scope = viewModelScope,
                 initialValue = SettingsUiState(dynamicColorAvailable = dynamicColorAvailable),
@@ -125,7 +139,10 @@ class SettingsViewModel @Inject constructor(
         snoozeMinutes = this[SettingsKeys.snoozeMinutes],
         perCalendarReminderOverride = this[SettingsKeys.perCalendarReminderOverride],
         perCalendarAllDayReminderOverride = this[SettingsKeys.perCalendarAllDayReminderOverride],
-        writableCalendars = calendars,
+        writableCalendars = calendars.filter { it.canModifyContents },
+        reminderCalendars = calendars,
+        mutedReminderCalendarIds = this[SettingsKeys.mutedReminderCalendarIds],
+        notificationCategoryHintDismissed = this[SettingsKeys.notificationCategoryHintDismissed],
         allowColorOnUnsupportedCalendars = this[SettingsKeys.allowColorOnUnsupportedCalendars],
         managedCalendarIds = specialDatesCalendars.values.toSet(),
     )
@@ -357,6 +374,130 @@ class SettingsViewModel @Inject constructor(
         }
     }
 
+    /**
+     * Re-plans, since a muted calendar armed no wake-up for its next reminder.
+     * Unmuting scans once more before the write, so the watermark starts at the
+     * unmute and nothing that came due while muted is replayed.
+     */
+    fun setCalendarRemindersEnabled(calendarId: Long, enabled: Boolean) {
+        viewModelScope.launch {
+            if (enabled) reminderScanner.scan()
+            prefs.setCalendarRemindersEnabled(calendarId, enabled)
+            reminderScanner.scan()
+        }
+    }
+
+    private val _channelStatus = MutableStateFlow(ReminderChannelStatus())
+
+    /** What the system blocks of the reminders; re-read with [refreshChannelStatus] (#145). */
+    val channelStatus: StateFlow<ReminderChannelStatus> = _channelStatus.asStateFlow()
+
+    private var channelStatusJob: Job? = null
+
+    private val _channelSounds = MutableStateFlow<Map<Long, ReminderSound>?>(null)
+
+    /** Each calendar's reminder sound (#518), null until first read; a calendar without a channel yet is absent. */
+    val channelSounds: StateFlow<Map<Long, ReminderSound>?> = _channelSounds.asStateFlow()
+
+    private val _soundFailed = Channel<SoundFailure>(Channel.CONFLATED)
+
+    /** Emits when a picked sound couldn't be applied; kept until the screen collects it. */
+    val soundFailed: Flow<SoundFailure> = _soundFailed.receiveAsFlow()
+
+    private val soundTitles = mutableMapOf<Uri, String?>()
+
+    fun refreshChannelStatus(calendarIds: Collection<Long>) {
+        channelStatusJob?.cancel()
+        channelStatusJob = viewModelScope.launch {
+            onChannels { status(calendarIds) }?.let { _channelStatus.value = it }
+            val sounds = onChannels { sounds(calendarIds) } ?: return@launch
+            _channelSounds.value = withContext(io) {
+                sounds.mapValues { (_, uri) ->
+                    ReminderSound(uri, uri?.let(::soundTitle))
+                }
+            }
+        }
+    }
+
+    /** A sound's title, cached unless it is a "default" alias whose target can change. */
+    private fun soundTitle(uri: Uri): String? {
+        if (uri.authority == Settings.AUTHORITY) return appContext.ringtoneTitle(uri)
+        return synchronized(soundTitles) { soundTitles.getOrPut(uri) { appContext.ringtoneTitle(uri) } }
+    }
+
+    /** Give [calendarId]'s reminders [sound] (null = silent), on a fresh channel (#518). */
+    fun setReminderSound(calendarId: Long, sound: Uri?) = applySound(sound) {
+        setSound(listOf(calendarId), sound, createMissing = true)
+    }
+
+    /**
+     * Give every switched-on calendar's reminders [sound]. Reads the calendars
+     * itself, so a pick returning after process death still finds them; those
+     * that only get a channel when something posts are left alone.
+     */
+    fun setReminderSoundForAll(sound: Uri?) = applySound(sound) {
+        try {
+            sync()
+        } catch (e: Exception) {
+            Log.w("SettingsViewModel", "Channel sync before a sound pick failed", e)
+        }
+        val ids = visibleCalendars.first().map { it.id }
+        ids.isNotEmpty() && setSound(ids, sound, createMissing = false)
+    }
+
+    private fun canRead(uri: Uri): Boolean = uri.authority == Settings.AUTHORITY ||
+        runCatching { appContext.contentResolver.openAssetFileDescriptor(uri, "r")?.close() != null }.getOrDefault(false)
+
+    /** Runs to completion even if the screen closes meanwhile, so a pick is never half-applied. */
+    private fun applySound(sound: Uri?, block: suspend ReminderChannels.() -> Boolean) {
+        viewModelScope.launch {
+            val failure = withContext(io + NonCancellable) {
+                try {
+                    // The system plays the sound but checks that Calendula could read it.
+                    when {
+                        sound != null && !canRead(sound) -> SoundFailure.Unreadable
+                        reminderChannels.block() -> null
+                        else -> SoundFailure.NotApplied
+                    }
+                } catch (e: Exception) {
+                    Log.w("SettingsViewModel", "Could not set the reminder sound", e)
+                    SoundFailure.NotApplied
+                }
+            }
+            failure?.let(_soundFailed::trySend)
+            refreshChannelStatus(visibleCalendars.first().map { it.id })
+        }
+    }
+
+    fun dismissNotificationCategoryHint() = save { dismissNotificationCategoryHint() }
+
+    /**
+     * The channel whose system screen to open for [calendarId] (#340), created
+     * if needed; null when only the app's own screen can help — the app or the
+     * calendar's account group is blocked there, or the channel couldn't be made.
+     */
+    suspend fun soundSettingsChannel(calendarId: Long): String? = onChannels {
+        val channelId = channelFor(calendarId) ?: return@onChannels null
+        val status = status(listOf(calendarId))
+        channelId.takeUnless { status.appBlocked || calendarId in status.groupBlockedCalendarIds }
+    }
+
+    /** Create the per-calendar channels before showing the app's channel list, even with reminders off. */
+    suspend fun syncReminderChannels() {
+        onChannels { sync() }
+    }
+
+    private suspend fun <T> onChannels(block: ReminderChannels.() -> T): T? = withContext(io) {
+        try {
+            reminderChannels.block()
+        } catch (e: CancellationException) {
+            throw e
+        } catch (e: Exception) {
+            Log.w("SettingsViewModel", "Reminder channel update failed", e)
+            null
+        }
+    }
+
     fun setAutofocusEventTitle(enabled: Boolean) = save { setAutofocusEventTitle(enabled) }
 
     fun setDefaultEventDuration(minutes: Int) = save { setDefaultEventDurationMinutes(minutes) }

app/src/main/java/de/jeanlucmakiola/calendula/ui/week/WeekScreen.kt

@@ -157,6 +157,7 @@ import de.jeanlucmakiola.calendula.ui.common.LocalEventMove
 import de.jeanlucmakiola.calendula.ui.common.MoveRequest
 import de.jeanlucmakiola.calendula.ui.common.MoveTarget
 import de.jeanlucmakiola.calendula.ui.common.TimelineDragController
+import de.jeanlucmakiola.calendula.ui.common.ghostsDerived
 import de.jeanlucmakiola.calendula.ui.common.StripDrag
 import de.jeanlucmakiola.calendula.ui.common.StripDrop
 import de.jeanlucmakiola.calendula.ui.common.TimelineDragOverlay
@@ -310,14 +311,6 @@ internal enum class TimelineKind(
     // A run of days often straddles two weeks, so no single number fits it.
     MultiDay(showWeekNumber = false, todayText = R.string.week_today_action, headerBias = 0f),
     Day(showWeekNumber = false, todayText = R.string.day_today_action, headerBias = -1f),
-    ;
-
-    fun title(start: LocalDate, end: LocalDate, locale: Locale, currentYear: Int, abbreviated: Boolean): String =
-        if (this == Day) {
-            formatDayTitle(start, locale, currentYear, abbreviated)
-        } else {
-            formatWeekTitle(start, end, locale, currentYear, abbreviated)
-        }
 }
 
 internal val CalendarView.timelineKind: TimelineKind
@@ -492,9 +485,10 @@ private fun PagedTimelineScreen(
     val jumpToToday = { jumpToDate(today) }
 
     val locale = currentLocale()
-    val (title, shortTitle) = remember(titleKind, weekStart, weekEnd, locale, today.year) {
-        titleKind.title(weekStart, weekEnd, locale, today.year, abbreviated = false) to
-            titleKind.title(weekStart, weekEnd, locale, today.year, abbreviated = true)
+    // The day view names the month too: its header already shows weekday and date (#501).
+    val (title, shortTitle) = remember(weekStart, weekEnd, locale, today.year) {
+        formatTimelineTitle(weekStart, weekEnd, locale, today.year, abbreviated = false) to
+            formatTimelineTitle(weekStart, weekEnd, locale, today.year, abbreviated = true)
     }
     PublishChrome(
         ScreenChrome(
@@ -591,7 +585,9 @@ private fun WeekContent(
                 eventId = drop.event.eventId,
                 beginMillis = drop.event.start.toEpochMilliseconds(),
                 endMillis = drop.event.end.toEpochMilliseconds(),
+                isAllDay = drop.event.isAllDay,
                 target = MoveTarget.Start(start),
+                token = drop.token,
             ),
         )
     }
@@ -610,7 +606,9 @@ private fun WeekContent(
                 eventId = drop.event.eventId,
                 beginMillis = drop.event.start.toEpochMilliseconds(),
                 endMillis = drop.event.end.toEpochMilliseconds(),
+                isAllDay = drop.event.isAllDay,
                 target = MoveTarget.Span(drop.start, drop.end),
+                token = drop.token,
             ),
         )
     }
@@ -622,10 +620,12 @@ private fun WeekContent(
                 eventId = drop.event.eventId,
                 beginMillis = drop.event.start.toEpochMilliseconds(),
                 endMillis = drop.event.end.toEpochMilliseconds(),
+                isAllDay = drop.event.isAllDay,
                 target = when (drop) {
                     is StripDrop.Days -> MoveTarget.ByDays(drop.days)
                     is StripDrop.Timed -> MoveTarget.Span(drop.start, drop.end)
                 },
+                token = drop.token,
             ),
         )
     }
@@ -767,8 +767,7 @@ private fun WeekPager(
             // Until its days arrive a page shows their frame without events.
             val empty = remember(pageSpan, today) { emptySpan(pageSpan, today) }
             // A bar held over other days in the strip makes room there before it is dropped.
-            val held = (dragController.stripDrag ?: dragController.stripSettling)
-                ?.takeIf { page == pagerState.currentPage }
+            val held = dragController.stripPreviews().takeIf { page == pagerState.currentPage }.orEmpty()
             val zone = LocalTimelineZone.current
             val shown = remember(loaded, held, zone) { loaded?.withStripPreview(held, zone) }
             val stripHeight = shown?.allDayStripHeight()
@@ -793,17 +792,24 @@ private fun WeekPager(
 }
 
 /**
- * [this] with the strip bar [held] sideways laid out at the days it is over, so
- * the bars there move aside live. The bar keeps its own event, and with it its
- * key and the gesture on it; one moved off the page keeps a lane it is not seen in.
+ * [this] with the strip bars [held] sideways laid out at the days they are over,
+ * so the bars there move aside live. Each bar keeps its own event, and with it
+ * its key and the gesture on it; one moved off the page keeps a lane it is not
+ * seen in.
  */
-internal fun WeekUiState.Success.withStripPreview(held: StripDrag?, zone: TimeZone): WeekUiState.Success {
-    if (held == null || held.overGrid || held.dayShift == 0) return this
-    val id = held.event.instanceId
-    val original = allDaySpans.firstOrNull { it.event.instanceId == id } ?: return this
-    val events = allDaySpans.map { if (it.event.instanceId == id) it.event.shiftedDays(held.dayShift, zone) else it.event }
-    val spans = layoutAllDay(events, days, zone).map { if (it.event.instanceId == id) it.copy(event = original.event) else it }
-    return copy(allDaySpans = if (spans.any { it.event.instanceId == id }) spans else spans + original.copy(lane = 0))
+internal fun WeekUiState.Success.withStripPreview(held: List<StripDrag>, zone: TimeZone): WeekUiState.Success {
+    val shifts = held.filter { !it.overGrid && it.dayShift != 0 }.associate { it.event.instanceId to it.dayShift }
+    if (shifts.isEmpty()) return this
+    val originals = allDaySpans.filter { it.event.instanceId in shifts }.associateBy { it.event.instanceId }
+    if (originals.isEmpty()) return this
+    val events = allDaySpans.map { span ->
+        shifts[span.event.instanceId]?.let { span.event.shiftedDays(it, zone) } ?: span.event
+    }
+    val spans = layoutAllDay(events, days, zone).map { span ->
+        originals[span.event.instanceId]?.let { span.copy(event = it.event) } ?: span
+    }
+    val laidOut = spans.mapTo(HashSet()) { it.event.instanceId }
+    return copy(allDaySpans = spans + originals.values.filter { it.event.instanceId !in laidOut }.map { it.copy(lane = 0) })
 }
 
 private fun EventInstance.shiftedDays(days: Int, zone: TimeZone): EventInstance {
@@ -811,6 +817,17 @@ private fun EventInstance.shiftedDays(days: Int, zone: TimeZone): EventInstance
     return copy(start = start.plus(days, DateTimeUnit.DAY, dates), end = end.plus(days, DateTimeUnit.DAY, dates))
 }
 
+/** Whether these bars draw the strip drop [drop] at the days it was dropped on. */
+private fun List<PlacedBar>.drawStripDrop(drop: StripDrag, zone: TimeZone): Boolean {
+    val target = drop.event.spanFirstDay(zone).plus(drop.dayShift, DateTimeUnit.DAY)
+    return any { bar ->
+        bar.event.instanceId != drop.event.instanceId &&
+            (bar.event.eventId == drop.event.eventId ||
+                (drop.event.title.isNotBlank() && bar.event.title == drop.event.title)) &&
+            bar.event.spanFirstDay(zone) == target
+    }
+}
+
 /** A page with no events yet, for one whose days are still loading. */
 private fun emptySpan(span: DaySpan, today: LocalDate): WeekUiState.Success {
     val days = (0 until span.count).map { span.start.plus(it, kotlinx.datetime.DateTimeUnit.DAY) }
@@ -1193,17 +1210,11 @@ private fun AllDayStrip(
     val sideways = held?.takeIf { !it.overGrid }
     val lifted = dragController.liftedInstanceId?.takeIf { active && dragController.stripDrag?.overGrid != false }
     val settling = dragController.stripSettling?.takeIf { active }
+    val heldStrips = dragController.heldStrips.takeIf { active }.orEmpty()
     // Seated once the re-read draws the event at the days it was dropped on.
-    LaunchedEffect(settling, bars) {
-        if (settling == null) return@LaunchedEffect
-        val target = settling.event.spanFirstDay(zone).plus(settling.dayShift, DateTimeUnit.DAY)
-        val landed = bars.any { bar ->
-            bar.event.instanceId != settling.event.instanceId &&
-                (bar.event.eventId == settling.event.eventId ||
-                    (settling.event.title.isNotBlank() && bar.event.title == settling.event.title)) &&
-                bar.event.spanFirstDay(zone) == target
-        }
-        if (landed) dragController.seatStrip()
+    LaunchedEffect(settling, heldStrips, bars) {
+        if (settling != null && bars.drawStripDrop(settling, zone)) dragController.seatStrip()
+        heldStrips.forEach { if (!it.seated && bars.drawStripDrop(it.drag, zone)) dragController.seatHeldStrip(it.token) }
     }
 
     Row(
@@ -1588,7 +1599,7 @@ private fun DayColumnCard(
                         widthFraction = 1f / block.laneCount,
                         y = top,
                         height = height,
-                        landing = dragController.ghosts(block),
+                        landing = dragController.ghostsDerived(block),
                     )
                     val topInset = hourCellBlockInset(showHourGrid, cuts.top)
                     val bottomInset = hourCellBlockInset(showHourGrid, cuts.bottom)
@@ -1756,7 +1767,7 @@ private fun EventBlock(
         onCancel = dragController::cancel,
         onRelease = { dragController.select(block.event, fromLift = draggable) },
     )
-    val lifted = draggable && dragController.ghosts(block)
+    val lifted = draggable && dragController.ghostsDerived(block)
     // Released in place, the block takes over the copy's lift without a dip.
     val takesOverLift = selected && dragController.selection?.fromLift == true
     val ghostFade = ghostAlpha(lifted)
@@ -2016,7 +2027,7 @@ private fun minToHm(min: Int, is24Hour: Boolean, locale: java.util.Locale): Stri
     formatMinuteOfDay(min, is24Hour, locale)
 
 /**
- * The week's title: just the month [weekStart] falls in.
+ * Every timeline's title, the day view's included: just the month [weekStart] falls in.
  *
  * The day numbers are already in the column headers directly below, so spelling
  * out "13.–19. Jul" restates them in the widest string in the bar. Naming the
@@ -2031,7 +2042,7 @@ private fun minToHm(min: Int, is24Hour: Boolean, locale: java.util.Locale): Stri
  * "December" with no year would be actively misleading while the reader is
  * looking straight at January dates.
  */
-private fun formatWeekTitle(
+private fun formatTimelineTitle(
     weekStart: LocalDate,
     weekEnd: LocalDate,
     locale: Locale,
@@ -2046,17 +2057,3 @@ private fun formatWeekTitle(
         forceYear = weekEnd.year != weekStart.year,
     )
 }
-
-/** The day's title: its weekday and date, abbreviated to the date alone when short of room. */
-private fun formatDayTitle(
-    date: LocalDate,
-    locale: Locale,
-    currentYear: Int,
-    abbreviated: Boolean = false,
-): String =
-    formatCalendarTitle(
-        date = date.toJavaLocalDate(),
-        locale = locale,
-        currentYear = currentYear,
-        skeleton = if (abbreviated) "dMMM" else "EEEdMMM",
-    )

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

@@ -110,6 +110,9 @@
     <string name="event_move_failed">Couldn\'t move the event</string>
     <string name="event_move_write_denied">Calendula needs write access to move events</string>
     <string name="event_move_gone">That event no longer exists</string>
+    <string name="event_move_stale">That event moved before your drop could be saved</string>
+    <string name="event_move_queue_full">Too many moves at once, so that one wasn\'t saved</string>
+    <string name="event_move_skipped">Moves made while the question was open weren\'t saved</string>
     <string name="event_move_blocked_series_end">Can\'t move an event past the end of its series</string>
     <string name="event_move_blocked_cancelled_series">A cancelled series can only move as a whole, and this would change which days it falls on</string>
 
@@ -728,7 +731,26 @@
     <string name="reminder_custom_amount">Amount</string>
     <string name="reminder_custom_set">Set</string>
     <string name="settings_calendar_reminders_title">Per-calendar reminders</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_reminders_hint">Turn notifications off or pick a sound per calendar, and override the default reminder for calendars you can edit.</string>
+    <string name="settings_calendar_notifications">Notifications</string>
+    <string name="settings_calendar_notifications_hint">Notify at this calendar\'s reminder times</string>
+    <string name="settings_calendar_notifications_off">Notifications off</string>
+    <string name="settings_notification_sound">Notification sound</string>
+    <string name="settings_notification_sound_silent">Silent</string>
+    <string name="settings_notification_sound_default">Default</string>
+    <!-- %1$s is the name of the device's default notification sound. -->
+    <string name="settings_notification_sound_default_named">Default (%1$s)</string>
+    <string name="settings_notification_sound_custom">Custom sound</string>
+    <string name="settings_notification_sound_failed">Couldn\'t change the notification sound</string>
+    <string name="settings_notification_sound_unreadable">Calendula can\'t play this sound. Pick another one.</string>
+    <string name="settings_notification_sound_mixed">Differs per calendar</string>
+    <string name="settings_notification_more">More notification settings</string>
+    <string name="settings_notification_sound_hint">Vibration, pop-ups and more for each calendar, in system settings</string>
+    <string name="settings_notifications_blocked">Blocked in system settings</string>
+    <string name="settings_notifications_blocked_hint">Blocked in system settings — tap to allow</string>
+    <string name="settings_notification_category_hint">On Samsung phones, new notification categories can start switched off. If a calendar\'s reminders don\'t arrive, check that its category is on.</string>
+    <string name="settings_notification_category_hint_open">Open settings</string>
+    <string name="settings_calendar_notification_sound_hint">Vibration, pop-ups and more for this calendar, in system settings</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>

app/src/test/java/de/jeanlucmakiola/calendula/data/prefs/SettingsPrefsTest.kt

@@ -601,6 +601,30 @@ class SettingsPrefsTest {
         assertThat(prefs.perCalendarEventDuration.first()).containsExactly(9L, 30)
     }
 
+    @Test
+    fun `calendar notifications default on and toggle per calendar`(
+        @TempDir tempDir: Path,
+    ) = runTest {
+        val prefs = testSettings(tempDir)
+        assertThat(prefs.mutedReminderCalendarIds.first()).isEmpty()
+        prefs.setCalendarRemindersEnabled(7L, false)
+        prefs.setCalendarRemindersEnabled(9L, false)
+        assertThat(prefs.mutedReminderCalendarIds.first()).containsExactly(7L, 9L)
+        prefs.setCalendarRemindersEnabled(7L, true)
+        assertThat(prefs.mutedReminderCalendarIds.first()).containsExactly(9L)
+    }
+
+    @Test
+    fun `reminder channel versions only grow`(
+        @TempDir tempDir: Path,
+    ) = runTest {
+        val prefs = testSettings(tempDir)
+        assertThat(prefs.reminderChannelVersions.first()).isEmpty()
+        assertThat(prefs.reserveReminderChannelVersions(mapOf(7L to 1))).containsExactly(7L, 1)
+        assertThat(prefs.reserveReminderChannelVersions(mapOf(7L to 1, 9L to 5))).containsExactly(7L, 2, 9L, 5)
+        assertThat(prefs.reminderChannelVersions.first()).containsExactly(7L, 2, 9L, 5)
+    }
+
     @Test
     fun `garbage per-calendar duration entries are dropped, the rest survive`(
         @TempDir tempDir: Path,

app/src/test/java/de/jeanlucmakiola/calendula/data/reminders/ReminderChannelPlanTest.kt

@@ -0,0 +1,200 @@
+package de.jeanlucmakiola.calendula.data.reminders
+
+import com.google.common.truth.Truth.assertThat
+import de.jeanlucmakiola.calendula.domain.CalendarSource
+import org.junit.jupiter.api.Test
+
+class ReminderChannelPlanTest {
+
+    private fun calendar(id: Long, account: String, type: String, local: Boolean = false) = CalendarSource(
+        id = id,
+        displayName = "Cal $id",
+        accountName = account,
+        accountType = type,
+        color = 0,
+        isVisibleInSystem = true,
+        isLocal = local,
+    )
+
+    @Test
+    fun `one channel per calendar, grouped by account`() {
+        val plan = planReminderChannels(
+            calendars = listOf(
+                calendar(1, "me@example.org", "com.google"),
+                calendar(2, "me@example.org", "com.google"),
+                calendar(3, "dav", "bitfire.at.davdroid"),
+            ),
+            existing = emptyList(),
+            existingGroupIds = emptyList(),
+            unnamed = "Unnamed",
+            description = DESC,
+        )
+        assertThat(plan.groups).hasSize(2)
+        assertThat(plan.channels.map { it.id })
+            .containsExactly(reminderChannelId(1), reminderChannelId(2), reminderChannelId(3))
+        assertThat(plan.channels[0].groupId).isEqualTo(plan.channels[1].groupId)
+        assertThat(plan.channels[2].groupId).isNotEqualTo(plan.channels[0].groupId)
+        assertThat(plan.staleChannelIds).isEmpty()
+    }
+
+    @Test
+    fun `device calendars share one group`() {
+        val plan = planReminderChannels(
+            calendars = listOf(
+                calendar(1, "Calendula", "LOCAL", local = true),
+                calendar(2, "Other", "LOCAL", local = true),
+            ),
+            existing = emptyList(),
+            existingGroupIds = emptyList(),
+            unnamed = "Unnamed",
+            description = DESC,
+        )
+        assertThat(plan.groups).hasSize(1)
+        assertThat(plan.groups.single().isLocal).isTrue()
+    }
+
+    @Test
+    fun `same account name under two types is ambiguous`() {
+        val plan = planReminderChannels(
+            calendars = listOf(
+                calendar(1, "me@example.org", "com.google"),
+                calendar(2, "me@example.org", "bitfire.at.davdroid"),
+                calendar(3, "work", "bitfire.at.davdroid"),
+            ),
+            existing = emptyList(),
+            existingGroupIds = emptyList(),
+            unnamed = "Unnamed",
+            description = DESC,
+        )
+        assertThat(plan.groups.filter { it.ambiguous }.map { it.accountType })
+            .containsExactly("com.google", "bitfire.at.davdroid")
+        assertThat(plan.groups.single { it.label == "work" }.ambiguous).isFalse()
+    }
+
+    @Test
+    fun `stale reminder channels and groups go, foreign ones stay`() {
+        val current = calendar(1, "me@example.org", "com.google")
+        fun plan(calendars: List<CalendarSource>, existing: List<String> = emptyList(), groups: List<String> = emptyList()) =
+            planReminderChannels(calendars, existing.map { ExistingReminderChannel(it, "Cal ${it.last()}", DESC, null) }, groups, "Unnamed", DESC)
+        val keptGroup = plan(listOf(current)).groups.single().id
+        val goneGroup = plan(listOf(calendar(9, "old", "com.google"))).groups.single().id
+        val result = plan(
+            calendars = listOf(current),
+            existing = listOf(reminderChannelId(1), reminderChannelId(9), LEGACY_REMINDER_CHANNEL_ID, "backup"),
+            groups = listOf(keptGroup, goneGroup, "other"),
+        )
+        assertThat(result.staleChannelIds).containsExactly(reminderChannelId(9))
+        assertThat(result.staleGroupIds).containsExactly(goneGroup)
+    }
+
+    @Test
+    fun `only missing or renamed channels are written`() {
+        val plan = planReminderChannels(
+            calendars = listOf(
+                calendar(1, "a", "com.google"),
+                calendar(2, "a", "com.google"),
+                calendar(3, "a", "com.google").copy(displayName = ""),
+                calendar(4, "a", "com.google"),
+            ),
+            existing = listOf(
+                ExistingReminderChannel(reminderChannelId(1), "Cal 1", DESC, "g"),
+                ExistingReminderChannel(reminderChannelId(4), "Cal 4", "Old description", "g"),
+                ExistingReminderChannel(reminderChannelId(2), "Old name", DESC, "g"),
+            ),
+            existingGroupIds = emptyList(),
+            unnamed = "Unnamed",
+            description = DESC,
+        )
+        assertThat(plan.channelsToWrite.map { it.calendarId }).containsExactly(2L, 3L, 4L)
+        assertThat(plan.channelsToWrite.single { it.calendarId == 3L }.name).isEqualTo("Unnamed")
+    }
+
+    @Test
+    fun `non-syncing calendars keep a channel but get none up front`() {
+        val quiet = calendar(2, "a", "com.google").copy(syncsEvents = false)
+        val fresh = planReminderChannels(listOf(quiet), emptyList(), emptyList(), "Unnamed", DESC)
+        assertThat(fresh.channelsToWrite).isEmpty()
+        assertThat(fresh.groupsInUse).isEmpty()
+        val posted = planReminderChannels(
+            calendars = listOf(quiet),
+            existing = listOf(ExistingReminderChannel(reminderChannelId(2), "Cal 2", DESC, null)),
+            existingGroupIds = emptyList(),
+            unnamed = "Unnamed",
+            description = DESC,
+        )
+        assertThat(posted.staleChannelIds).isEmpty()
+        assertThat(posted.channelsToWrite.map { it.calendarId }).containsExactly(2L)
+        assertThat(posted.groupsInUse).hasSize(1)
+    }
+
+    @Test
+    fun `blocked calendars follow app, channel and group`() {
+        val channels = mapOf(
+            reminderChannelId(1) to ReminderChannelState(blocked = true, groupId = "g1"),
+            reminderChannelId(2) to ReminderChannelState(blocked = false, groupId = "g2"),
+            reminderChannelId(3) to ReminderChannelState(blocked = false, groupId = "g1"),
+        )
+        val ids = listOf(1L, 2L, 3L, 4L)
+        val groupOff = reminderChannelStatus(ids, appEnabled = true, channels, blockedGroupIds = setOf("g2"))
+        assertThat(groupOff.blockedCalendarIds).containsExactly(1L, 2L)
+        assertThat(groupOff.groupBlockedCalendarIds).containsExactly(2L)
+        assertThat(reminderChannelStatus(ids, appEnabled = true, channels, blockedGroupIds = emptySet()).blockedCalendarIds)
+            .containsExactly(1L)
+        val appOff = reminderChannelStatus(ids, appEnabled = false, channels, blockedGroupIds = emptySet())
+        assertThat(appOff.appBlocked).isTrue()
+        assertThat(appOff.blockedCalendarIds).containsExactly(1L, 2L, 3L, 4L)
+    }
+
+    @Test
+    fun `channel ids round-trip with versions`() {
+        assertThat(parseReminderChannelId(reminderChannelId(7))).isEqualTo(7L to 0)
+        assertThat(parseReminderChannelId(reminderChannelId(7, 3))).isEqualTo(7L to 3)
+        assertThat(parseReminderChannelId("reminders.calendar.7.v0")).isNull()
+        assertThat(parseReminderChannelId("reminders.calendar.x")).isNull()
+        assertThat(parseReminderChannelId(LEGACY_REMINDER_CHANNEL_ID)).isNull()
+    }
+
+    @Test
+    fun `a version bump retires the old channel unless it is showing`() {
+        val existing = listOf(
+            ExistingReminderChannel(reminderChannelId(1), "Cal 1", DESC, "g"),
+            ExistingReminderChannel(reminderChannelId(2), "Cal 2", DESC, "g"),
+        )
+        val plan = planReminderChannels(
+            calendars = listOf(calendar(1, "a", "com.google"), calendar(2, "a", "com.google")),
+            existing = existing,
+            existingGroupIds = emptyList(),
+            unnamed = "Unnamed",
+            description = DESC,
+            versions = mapOf(1L to 2, 2L to 1),
+            showingChannelIds = setOf(reminderChannelId(2)),
+        )
+        assertThat(plan.channels.map { it.id }).containsExactly(reminderChannelId(1, 2), reminderChannelId(2, 1))
+        assertThat(plan.staleChannelIds).containsExactly(reminderChannelId(1))
+        assertThat(plan.keptChannelIds).containsExactly(reminderChannelId(2))
+    }
+
+    @Test
+    fun `the current version is the highest that exists, else the high-water mark`() {
+        val versions = currentReminderChannelVersions(
+            existingChannelIds = listOf(reminderChannelId(1), reminderChannelId(1, 2), reminderChannelId(3), "backup"),
+            highWater = mapOf(1L to 5, 2L to 4),
+        )
+        // Calendar 1 reserved v5 but never wrote it, so v2 stays current.
+        assertThat(versions).containsExactly(1L, 2, 2L, 4, 3L, 0)
+    }
+
+    @Test
+    fun `status reads the current channel version`() {
+        val channels = mapOf(
+            reminderChannelId(1) to ReminderChannelState(blocked = true, groupId = null),
+            reminderChannelId(1, 2) to ReminderChannelState(blocked = false, groupId = null),
+        )
+        val status = reminderChannelStatus(listOf(1L), true, channels, emptySet(), versions = mapOf(1L to 2))
+        assertThat(status.blockedCalendarIds).isEmpty()
+    }
+
+    private companion object {
+        const val DESC = "Reminders"
+    }
+}

app/src/test/java/de/jeanlucmakiola/calendula/ui/common/RescheduleViewModelTest.kt

@@ -13,10 +13,12 @@ import de.jeanlucmakiola.calendula.testEvent
 import de.jeanlucmakiola.calendula.testPrefs
 import de.jeanlucmakiola.calendula.testRepository
 import de.jeanlucmakiola.calendula.testSettings
+import kotlinx.coroutines.CoroutineDispatcher
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.Job
 import kotlinx.coroutines.launch
+import kotlinx.coroutines.test.StandardTestDispatcher
 import kotlinx.coroutines.test.advanceUntilIdle
 import kotlinx.coroutines.test.runTest
 import kotlinx.datetime.LocalDate
@@ -79,15 +81,43 @@ class RescheduleViewModelTest {
         status = status,
     )
 
-    private fun viewModel(tempDir: Path, fake: FakeCalendarDataSource): RescheduleViewModel {
+    /**
+     * [present] are the events whose occurrence the provider still reports where
+     * a drop picked it up; [io] a [StandardTestDispatcher] keeps a drop in flight.
+     */
+    private fun viewModel(
+        tempDir: Path,
+        fake: FakeCalendarDataSource,
+        present: List<Long> = listOf(42L, 7L),
+        io: CoroutineDispatcher = dispatcher,
+    ): RescheduleViewModel {
+        fake.occurrencesAt(present)
         val repo = testRepository(
-            fake, tempDir, dispatcher,
+            fake, tempDir, io,
             prefs = testPrefs(tempDir, CoroutineScope(dispatcher)),
             settings = testSettings(tempDir, CoroutineScope(dispatcher)),
         )
-        return RescheduleViewModel(repo, dispatcher, FakeZoneSource())
+        return RescheduleViewModel(repo, io, FakeZoneSource())
     }
 
+    private fun slowViewModel(tempDir: Path, fake: FakeCalendarDataSource): RescheduleViewModel =
+        viewModel(tempDir, fake, io = StandardTestDispatcher(dispatcher.scheduler))
+
+    /** Every query answers with an occurrence of each of [ids] exactly at the queried span. */
+    private fun FakeCalendarDataSource.occurrencesAt(ids: List<Long>) {
+        instancesResult = { begin, end ->
+            ids.map { id ->
+                testEvent(
+                    id = id,
+                    start = Instant.fromEpochMilliseconds(begin),
+                    end = Instant.fromEpochMilliseconds(end),
+                )
+            }
+        }
+    }
+
+    private val RescheduleViewModel.abandonedCount: Int get() = drops.value.abandoned.size
+
     private fun CoroutineScope.activate(vm: RescheduleViewModel): Job =
         launch { vm.movableCalendarIds.collect {} }
 
@@ -97,6 +127,8 @@ class RescheduleViewModelTest {
         beginMillis = beginMillis,
         endMillis = endMillis,
         target = MoveTarget.ByDays(2),
+        isAllDay = false,
+        token = nextMoveToken(),
     )
 
     /** A drop an hour later, expressed the way a timeline drag expresses one. */
@@ -105,6 +137,8 @@ class RescheduleViewModelTest {
         beginMillis = beginMillis,
         endMillis = endMillis,
         target = MoveTarget.Start(Instant.fromEpochMilliseconds(beginMillis + 3_600_000L)),
+        isAllDay = false,
+        token = nextMoveToken(),
     )
 
     /** The end dragged an hour later, the start left where it is. */
@@ -116,6 +150,8 @@ class RescheduleViewModelTest {
             Instant.fromEpochMilliseconds(beginMillis),
             Instant.fromEpochMilliseconds(endMillis + 3_600_000L),
         ),
+        isAllDay = false,
+        token = nextMoveToken(),
     )
 
     @Test
@@ -259,21 +295,228 @@ class RescheduleViewModelTest {
     }
 
     @Test
-    fun `a second drop is refused while the first is still in flight`(
+    fun `a drop of another event waits for the one in flight, then lands`(
         @TempDir tempDir: Path,
     ) = runTest(dispatcher) {
         val fake = FakeCalendarDataSource().apply {
-            eventDetailResult = { detail(rrule = "FREQ=WEEKLY;BYDAY=MO") }
+            eventDetailResult = { detail() }
         }
+        val vm = slowViewModel(tempDir, fake)
+
+        val first = oneHourLater()
+        val second = toWednesday().copy(eventId = 7L, token = nextMoveToken())
+        assertThat(vm.move(first)).isTrue()
+        assertThat(vm.move(second)).isTrue()
+        assertThat(vm.drops.value.pending).containsExactly(first.token, second.token)
+        advanceUntilIdle()
+
+        assertThat(fake.updatedEvents.map { it.first }).containsExactly(42L, 7L).inOrder()
+        assertThat(vm.drops.value).isEqualTo(DropStates())
+        assertThat(vm.inFlight.value).isFalse()
+    }
+
+    @Test
+    fun `a failed drop lets go of its own copy only, not the one queued behind it`(
+        @TempDir tempDir: Path,
+    ) = runTest(dispatcher) {
+        val fake = FakeCalendarDataSource().apply {
+            eventDetailResult = { detail() }
+        }
+        val vm = slowViewModel(tempDir, fake)
+
+        // Zero distance: refused in prepare.
+        val nowhere = oneHourLater().copy(
+            target = MoveTarget.Start(Instant.fromEpochMilliseconds(beginMillis)),
+            token = nextMoveToken(),
+        )
+        val queued = toWednesday().copy(eventId = 7L, token = nextMoveToken())
+        vm.move(nowhere)
+        vm.move(queued)
+        advanceUntilIdle()
+
+        assertThat(vm.drops.value.abandoned).containsExactly(nowhere.token)
+        assertThat(fake.updatedEvents.map { it.first }).containsExactly(7L)
+    }
+
+    @Test
+    fun `the same event dropped twice ends up where it was dropped last`(
+        @TempDir tempDir: Path,
+    ) = runTest(dispatcher) {
+        val hour = 3_600_000L
+        val fake = FakeCalendarDataSource()
+        val vm = slowViewModel(tempDir, fake)
+        // Once the first drop is written, the event sits an hour later.
+        fake.eventDetailResult = {
+            if (fake.updatedEvents.isEmpty()) detail() else detail(anchorMillis = beginMillis + hour)
+        }
+        fake.instancesResult = { _, _ ->
+            val shift = if (fake.updatedEvents.isEmpty()) 0L else hour
+            listOf(
+                testEvent(
+                    id = 42L,
+                    start = Instant.fromEpochMilliseconds(beginMillis + shift),
+                    end = Instant.fromEpochMilliseconds(endMillis + shift),
+                ),
+            )
+        }
+
+        vm.move(oneHourLater())
+        // Picked up from where the grid still drew it, and dropped two days on.
+        vm.move(toWednesday())
+        advanceUntilIdle()
+
+        assertThat(fake.updatedEvents).hasSize(2)
+        val last = fake.updatedEvents.last().third
+        assertThat(last.start.dateTime).isEqualTo(LocalDateTime(LocalDate(2026, 6, 10), LocalTime(13, 0)))
+    }
+
+    @Test
+    fun `a drop on a series written moments ago is not written`(
+        @TempDir tempDir: Path,
+    ) = runTest(dispatcher) {
+        // A whole-series write shifts every occurrence; the grid still draws the
+        // old ones, and another occurrence may now sit at the dragged time.
+        val fake = FakeCalendarDataSource().apply { eventDetailResult = { detail(rrule = "FREQ=DAILY") } }
         val vm = viewModel(tempDir, fake)
+        vm.move(oneHourLater())
+        advanceUntilIdle()
+        vm.moveWithScope(RecurringWriteScope.AllEvents)
+        advanceUntilIdle()
+        vm.consumeOutcome()
 
-        assertThat(vm.move(toWednesday())).isTrue()
+        val again = toWednesday()
+        vm.move(again)
         advanceUntilIdle()
 
-        // Parked on the scope dialog, so the first drop still owns the pipeline.
-        assertThat(vm.move(oneHourLater())).isFalse()
+        assertThat(vm.scopePrompt.value).isNull()
+        assertThat(vm.outcome.value).isEqualTo(MoveOutcome.Stale)
+        assertThat(vm.drops.value.abandoned).containsExactly(again.token)
+        assertThat(fake.updatedEvents).hasSize(1)
+    }
+
+    @Test
+    fun `a single occurrence written leaves the rest of its series movable`(
+        @TempDir tempDir: Path,
+    ) = runTest(dispatcher) {
+        val fake = FakeCalendarDataSource().apply { eventDetailResult = { detail(rrule = "FREQ=WEEKLY") } }
+        val vm = viewModel(tempDir, fake)
+        vm.move(oneHourLater())
         advanceUntilIdle()
-        assertThat(fake.updatedEvents).isEmpty()
+        vm.moveWithScope(RecurringWriteScope.ThisEvent)
+        advanceUntilIdle()
+
+        // Another occurrence, a week on.
+        val week = 7 * 86_400_000L
+        vm.move(oneHourLater().copy(beginMillis = beginMillis + week, endMillis = endMillis + week, token = nextMoveToken()))
+        advanceUntilIdle()
+
+        assertThat(vm.scopePrompt.value).isNotNull()
+    }
+
+    @Test
+    fun `chip messages wait their turn instead of replacing each other`(
+        @TempDir tempDir: Path,
+    ) = runTest(dispatcher) {
+        val fake = FakeCalendarDataSource().apply {
+            eventDetailResult = { id ->
+                if (id == 42L) detail(rrule = "FREQ=WEEKLY;BYDAY=MO,WE", status = EventStatus.Cancelled) else detail()
+            }
+        }
+        val vm = slowViewModel(tempDir, fake)
+
+        vm.move(toWednesday())
+        vm.move(toWednesday().copy(eventId = 7L, token = nextMoveToken()))
+        advanceUntilIdle()
+
+        assertThat(vm.outcome.value).isEqualTo(MoveOutcome.BlockedCancelledSeries)
+        vm.consumeOutcome()
+        assertThat((vm.outcome.value as MoveOutcome.Moved).undo?.eventId).isEqualTo(7L)
+        vm.consumeOutcome()
+        assertThat(vm.outcome.value).isNull()
+    }
+
+    @Test
+    fun `a full queue says so`(@TempDir tempDir: Path) = runTest(dispatcher) {
+        val fake = FakeCalendarDataSource().apply { eventDetailResult = { detail() } }
+        val vm = slowViewModel(tempDir, fake)
+
+        repeat(9) { i -> vm.move(toWednesday().copy(eventId = 100L + i, token = nextMoveToken())) }
+        val refused = toWednesday().copy(eventId = 200L, token = nextMoveToken())
+        assertThat(vm.move(refused)).isFalse()
+
+        assertThat(vm.drops.value.abandoned).containsExactly(refused.token)
+        assertThat(vm.outcome.value).isEqualTo(MoveOutcome.QueueFull)
+    }
+
+    @Test
+    fun `a deleted event reports itself as gone, not moved`(@TempDir tempDir: Path) = runTest(dispatcher) {
+        val fake = FakeCalendarDataSource().apply { eventDetailResult = { null } }
+        val vm = viewModel(tempDir, fake, present = emptyList())
+
+        vm.move(oneHourLater())
+        advanceUntilIdle()
+
+        assertThat(vm.outcome.value).isEqualTo(MoveOutcome.Gone)
+    }
+
+    @Test
+    fun `drops waiting when a scope dialog opens are cancelled, not held behind it`(
+        @TempDir tempDir: Path,
+    ) = runTest(dispatcher) {
+        val fake = FakeCalendarDataSource().apply {
+            eventDetailResult = { id -> if (id == 42L) detail(rrule = "FREQ=WEEKLY") else detail() }
+        }
+        val vm = slowViewModel(tempDir, fake)
+
+        vm.move(oneHourLater())
+        val queued = toWednesday().copy(eventId = 7L, token = nextMoveToken())
+        vm.move(queued)
+        advanceUntilIdle()
+
+        assertThat(vm.scopePrompt.value).isNotNull()
+        assertThat(vm.drops.value.abandoned).containsExactly(queued.token)
+        assertThat(vm.outcome.value).isEqualTo(MoveOutcome.Skipped)
+
+        // One made while the dialog is up is refused the same way.
+        val during = toWednesday().copy(eventId = 7L, token = nextMoveToken())
+        assertThat(vm.move(during)).isFalse()
+
+        vm.moveWithScope(RecurringWriteScope.AllEvents)
+        advanceUntilIdle()
+        assertThat(fake.updatedEvents.map { it.first }).containsExactly(42L)
+        // The skip has its turn, then the move it waited on, with its Undo.
+        assertThat(vm.outcome.value).isEqualTo(MoveOutcome.Skipped)
+        vm.consumeOutcome()
+        assertThat((vm.outcome.value as MoveOutcome.Moved).undo?.eventId).isEqualTo(42L)
+    }
+
+    @Test
+    fun `the first move of a run keeps the chip and its undo`(@TempDir tempDir: Path) = runTest(dispatcher) {
+        val fake = FakeCalendarDataSource().apply { eventDetailResult = { detail() } }
+        val vm = slowViewModel(tempDir, fake)
+
+        vm.move(oneHourLater())
+        vm.move(toWednesday().copy(eventId = 7L, token = nextMoveToken()))
+        advanceUntilIdle()
+
+        val shown = vm.outcome.value as MoveOutcome.Moved
+        assertThat(fake.updatedEvents).hasSize(2)
+        assertThat(shown.undo?.eventId).isEqualTo(42L)
+    }
+
+    @Test
+    fun `a later move of the same event takes the first move's undo away`(
+        @TempDir tempDir: Path,
+    ) = runTest(dispatcher) {
+        val fake = FakeCalendarDataSource().apply { eventDetailResult = { detail() } }
+        val vm = slowViewModel(tempDir, fake)
+
+        vm.move(oneHourLater())
+        vm.move(toWednesday())
+        advanceUntilIdle()
+
+        assertThat(fake.updatedEvents).hasSize(2)
+        assertThat((vm.outcome.value as MoveOutcome.Moved).undo).isNull()
     }
 
     @Test
@@ -284,19 +527,19 @@ class RescheduleViewModelTest {
         advanceUntilIdle()
         val undo = (vm.outcome.value as MoveOutcome.Moved).undo!!
 
-        // A second drop parks on its scope dialog, which holds the pipeline.
+        // A second drop, of another event, parks on its scope dialog, which holds the pipeline.
         fake.eventDetailResult = { detail(rrule = "FREQ=WEEKLY;BYDAY=MO") }
-        vm.move(toWednesday())
+        vm.move(toWednesday().copy(eventId = 7L, token = nextMoveToken()))
         advanceUntilIdle()
 
-        val abandoned = vm.abandoned.value
+        val abandoned = vm.abandonedCount
         assertThat(vm.undo(undo)).isFalse()
         advanceUntilIdle()
         assertThat(fake.updatedEvents).hasSize(1)
         // Nothing ticks: the refusal started no journey of its own, and the
         // counter is global — a tick here would release the copy the drop that
         // *is* in flight is holding, before the grid has drawn it.
-        assertThat(vm.abandoned.value).isEqualTo(abandoned)
+        assertThat(vm.abandonedCount).isEqualTo(abandoned)
     }
 
     @Test
@@ -311,13 +554,13 @@ class RescheduleViewModelTest {
         advanceUntilIdle()
         val undo = (vm.outcome.value as MoveOutcome.Moved).undo!!
 
-        val abandoned = vm.abandoned.value
+        val abandoned = vm.abandonedCount
         fake.writeError = SecurityException("permission revoked")
         assertThat(vm.undo(undo)).isTrue()
         advanceUntilIdle()
 
         assertThat(vm.outcome.value).isEqualTo(MoveOutcome.WriteDenied)
-        assertThat(vm.abandoned.value).isEqualTo(abandoned + 1)
+        assertThat(vm.abandonedCount).isEqualTo(abandoned + 1)
     }
 
     @Test
@@ -330,12 +573,12 @@ class RescheduleViewModelTest {
         advanceUntilIdle()
         val undo = (vm.outcome.value as MoveOutcome.Moved).undo!!
 
-        val abandoned = vm.abandoned.value
+        val abandoned = vm.abandonedCount
         vm.undo(undo)
         advanceUntilIdle()
 
         assertThat(vm.outcome.value).isEqualTo(MoveOutcome.Undone)
-        assertThat(vm.abandoned.value).isEqualTo(abandoned)
+        assertThat(vm.abandonedCount).isEqualTo(abandoned)
     }
 
     @Test
@@ -415,6 +658,8 @@ class RescheduleViewModelTest {
                 target = MoveTarget.Start(
                     Instant.fromEpochMilliseconds(beginMillis + 26 * 3_600_000L),
                 ),
+                isAllDay = false,
+                token = nextMoveToken(),
             ),
         )
         advanceUntilIdle()
@@ -435,6 +680,8 @@ class RescheduleViewModelTest {
                 beginMillis = beginMillis,
                 endMillis = endMillis,
                 target = MoveTarget.Start(Instant.fromEpochMilliseconds(beginMillis)),
+                isAllDay = false,
+                token = nextMoveToken(),
             ),
         )
         advanceUntilIdle()
@@ -556,17 +803,19 @@ class RescheduleViewModelTest {
                 beginMillis = beginMillis,
                 endMillis = endMillis,
                 target = MoveTarget.Start(Instant.fromEpochMilliseconds(beginMillis)),
+                isAllDay = false,
+                token = nextMoveToken(),
             ),
         )).isTrue()
         advanceUntilIdle()
-        assertThat(vm.abandoned.value).isEqualTo(1)
+        assertThat(vm.abandonedCount).isEqualTo(1)
 
         // Refused by the provider, after the write was attempted.
         fake.writeError = SecurityException("revoked")
         vm.move(oneHourLater())
         advanceUntilIdle()
         assertThat(vm.outcome.value).isEqualTo(MoveOutcome.WriteDenied)
-        assertThat(vm.abandoned.value).isEqualTo(2)
+        assertThat(vm.abandonedCount).isEqualTo(2)
     }
 
     @Test
@@ -580,11 +829,11 @@ class RescheduleViewModelTest {
 
         vm.move(oneHourLater())
         advanceUntilIdle()
-        assertThat(vm.abandoned.value).isEqualTo(0)
+        assertThat(vm.abandonedCount).isEqualTo(0)
 
         vm.cancelScope()
         advanceUntilIdle()
-        assertThat(vm.abandoned.value).isEqualTo(1)
+        assertThat(vm.abandonedCount).isEqualTo(1)
     }
 
     @Test
@@ -596,7 +845,7 @@ class RescheduleViewModelTest {
         advanceUntilIdle()
 
         assertThat(vm.outcome.value).isInstanceOf(MoveOutcome.Moved::class.java)
-        assertThat(vm.abandoned.value).isEqualTo(0)
+        assertThat(vm.abandonedCount).isEqualTo(0)
     }
 
     @Test
@@ -668,6 +917,8 @@ class RescheduleViewModelTest {
                 beginMillis = beginMillis,
                 endMillis = endMillis,
                 target = MoveTarget.Span(sundayEvening, Instant.fromEpochMilliseconds(endMillis)),
+                isAllDay = false,
+                token = nextMoveToken(),
             ),
         )
         advanceUntilIdle()
@@ -709,7 +960,7 @@ class RescheduleViewModelTest {
 
         assertThat(vm.scopePrompt.value).isNull()
         assertThat(vm.outcome.value).isEqualTo(MoveOutcome.BlockedCancelledSeries)
-        assertThat(vm.abandoned.value).isEqualTo(1)
+        assertThat(vm.abandonedCount).isEqualTo(1)
         assertThat(fake.updatedEvents).isEmpty()
         assertThat(fake.updatedOccurrences).isEmpty()
     }
@@ -739,6 +990,8 @@ class RescheduleViewModelTest {
                 beginMillis = dayStart,
                 endMillis = dayStart + 86_400_000L,
                 target = MoveTarget.Span(start, Instant.fromEpochMilliseconds(endMillis)),
+                isAllDay = true,
+                token = nextMoveToken(),
             ),
         )
         advanceUntilIdle()
@@ -775,6 +1028,8 @@ class RescheduleViewModelTest {
                 beginMillis = dayStart,
                 endMillis = dayStart + 86_400_000L,
                 target = MoveTarget.Span(eight, eight + 1.hours),
+                isAllDay = true,
+                token = nextMoveToken(),
             ),
         )
         advanceUntilIdle()

app/src/test/java/de/jeanlucmakiola/calendula/ui/common/TimelineDropTest.kt

@@ -53,7 +53,7 @@ class TimelineDropTest {
     @Test
     fun `dropping the head asks for exactly where it landed`() {
         val target = LocalDate(2026, 9, 2)
-        val drop = TimelineDrop(overnight, target, 20 * 60, clipOffsetMin = 0)
+        val drop = TimelineDrop(overnight, target, 20 * 60, clipOffsetMin = 0, token = 0L)
 
         assertThat(drop.startInstant(zone)).isEqualTo(target.atTime(20, 0).toInstant(zone))
     }
@@ -63,7 +63,7 @@ class TimelineDropTest {
         val tail = blockOn(sun)
         val offset = tail.clipOffsetMinutes(sun, zone)
         // Dragged three days back, same height in the column: Sun 6 -> Thu 3.
-        val drop = TimelineDrop(overnight, LocalDate(2026, 9, 3), 0, offset)
+        val drop = TimelineDrop(overnight, LocalDate(2026, 9, 3), 0, offset, token = 0L)
 
         // The event began Sat 5 Sep 20:00, so it now begins Wed 2 Sep 20:00 —
         // the whole event moved three days, and no time of day was invented.
@@ -75,7 +75,7 @@ class TimelineDropTest {
     fun `dragging the tail down the column re-times the event across midnight`() {
         val offset = blockOn(sun).clipOffsetMinutes(sun, zone)
         // Tail top pulled from 00:00 to 03:00 on its own day.
-        val drop = TimelineDrop(overnight, sun, 3 * 60, offset)
+        val drop = TimelineDrop(overnight, sun, 3 * 60, offset, token = 0L)
 
         assertThat(drop.startInstant(zone)).isEqualTo(sat.atTime(23, 0).toInstant(zone))
     }
@@ -84,7 +84,7 @@ class TimelineDropTest {
     fun `pulling the tail above its own midnight moves the event earlier`() {
         val offset = blockOn(sun).clipOffsetMinutes(sun, zone)
         // The tail's top edge dragged an hour above the midnight it rests on.
-        val drop = TimelineDrop(overnight, sun, -60, offset)
+        val drop = TimelineDrop(overnight, sun, -60, offset, token = 0L)
 
         // Event was Sat 20:00 to Sun 08:00; it now begins an hour earlier.
         assertThat(drop.startInstant(zone)).isEqualTo(sat.atTime(19, 0).toInstant(zone))
@@ -92,7 +92,7 @@ class TimelineDropTest {
 
     @Test
     fun `a top edge dragged past the next midnight resolves onto the day after`() {
-        val drop = TimelineDrop(overnight, sat, 25 * 60, clipOffsetMin = 0)
+        val drop = TimelineDrop(overnight, sat, 25 * 60, clipOffsetMin = 0, token = 0L)
 
         assertThat(drop.startInstant(zone)).isEqualTo(sun.atTime(1, 0).toInstant(zone))
     }
@@ -130,7 +130,7 @@ class TimelineDropTest {
         val tail = layoutDay(listOf(overnightIntoDst), sun, berlin).single()
         val offset = tail.clipOffsetMinutes(sun, berlin)
         // Dropped back onto its own slot a week earlier, clear of the boundary.
-        val drop = TimelineDrop(overnightIntoDst, LocalDate(2026, 3, 22), 0, offset)
+        val drop = TimelineDrop(overnightIntoDst, LocalDate(2026, 3, 22), 0, offset, token = 0L)
 
         assertThat(drop.startInstant(berlin))
             .isEqualTo(LocalDate(2026, 3, 21).atTime(22, 0).toInstant(berlin))
@@ -155,7 +155,7 @@ class TimelineDropTest {
         )
         val block = layoutDay(listOf(event), fallBack, brussels).single()
         assertThat(block.clipOffsetMinutes(fallBack, brussels)).isEqualTo(0)
-        val drop = TimelineDrop(event, fallBack, block.startMin, clipOffsetMin = 0)
+        val drop = TimelineDrop(event, fallBack, block.startMin, clipOffsetMin = 0, token = 0L)
         assertThat(drop.startInstant(brussels)).isEqualTo(event.start)
     }
 
@@ -168,7 +168,7 @@ class TimelineDropTest {
         val tail = layoutDay(listOf(event), fallBack, brussels).single()
         val offset = tail.clipOffsetMinutes(fallBack, brussels)
         assertThat(offset).isEqualTo(2 * 60)
-        val drop = TimelineDrop(event, fallBack, tail.startMin, clipOffsetMin = offset)
+        val drop = TimelineDrop(event, fallBack, tail.startMin, clipOffsetMin = offset, token = 0L)
         assertThat(drop.startInstant(brussels)).isEqualTo(event.start)
     }
 
@@ -189,7 +189,7 @@ class TimelineDropTest {
             end = Instant.parse("2026-10-25T02:30:00Z"),
         )
         val block = layoutDay(listOf(event), fallBack, brussels).single()
-        val drop = TimelineDrop(event, fallBack, block.startMin + 15, clipOffsetMin = 0)
+        val drop = TimelineDrop(event, fallBack, block.startMin + 15, clipOffsetMin = 0, token = 0L)
         assertThat(drop.startInstant(brussels)).isEqualTo(Instant.parse("2026-10-25T01:45:00Z"))
     }
 
@@ -234,7 +234,7 @@ class TimelineDropTest {
             start = Instant.parse("2026-10-25T01:30:00Z"),
             end = Instant.parse("2026-10-25T03:00:00Z"),
         )
-        val drop = resizedDrop(event, ResizeEdge.Bottom, fallBack, 2 * 60 + 30, 15, brussels)
+        val drop = resizedSpan(event, ResizeEdge.Bottom, fallBack, 2 * 60 + 30, 15, brussels)
         assertThat(drop.start).isEqualTo(event.start)
         assertThat(drop.end).isEqualTo(Instant.parse("2026-10-25T01:45:00Z"))
     }
@@ -246,7 +246,7 @@ class TimelineDropTest {
             start = Instant.parse("2026-10-25T00:30:00Z"),
             end = Instant.parse("2026-10-25T01:15:00Z"),
         )
-        val drop = resizedDrop(event, ResizeEdge.Top, fallBack, 2 * 60, 60, brussels)
+        val drop = resizedSpan(event, ResizeEdge.Top, fallBack, 2 * 60, 60, brussels)
         assertThat(drop.start).isEqualTo(Instant.parse("2026-10-25T00:00:00Z"))
         assertThat(drop.end).isEqualTo(event.end)
     }
@@ -258,7 +258,7 @@ class TimelineDropTest {
             start = Instant.parse("2026-10-25T00:20:00Z"),
             end = Instant.parse("2026-10-25T01:10:00Z"),
         )
-        val drop = resizedDrop(event, ResizeEdge.Bottom, fallBack, 2 * 60 + 20, 30, brussels)
+        val drop = resizedSpan(event, ResizeEdge.Bottom, fallBack, 2 * 60 + 20, 30, brussels)
         assertThat(drop.end).isEqualTo(Instant.parse("2026-10-25T00:50:00Z"))
     }
 
@@ -270,7 +270,7 @@ class TimelineDropTest {
             start = Instant.parse("2026-10-24T23:00:00Z"),
             end = Instant.parse("2026-10-25T03:00:00Z"),
         )
-        val drop = resizedDrop(event, ResizeEdge.Bottom, fallBack, 60, 75, brussels)
+        val drop = resizedSpan(event, ResizeEdge.Bottom, fallBack, 60, 75, brussels)
         assertThat(drop.end).isEqualTo(Instant.parse("2026-10-25T00:15:00Z"))
     }
 }

app/src/test/java/de/jeanlucmakiola/calendula/ui/week/WeekLayoutTest.kt

@@ -356,12 +356,12 @@ class WeekLayoutTest {
         )
         assertThat(state.allDaySpans.map { it.lane }).containsExactly(0, 0)
 
-        val preview = state.withStripPreview(StripDrag(held, dayShift = 2), zone).allDaySpans
+        val preview = state.withStripPreview(listOf(StripDrag(held, dayShift = 2)), zone).allDaySpans
         val moved = preview.single { it.event.instanceId == held.instanceId }
 
         assertThat(moved.event).isEqualTo(held)
         assertThat(moved.startCol).isEqualTo(2)
         assertThat(preview.map { it.lane }).containsExactly(0, 1)
-        assertThat(state.withStripPreview(StripDrag(held, dayShift = 2, overGrid = true), zone)).isSameInstanceAs(state)
+        assertThat(state.withStripPreview(listOf(StripDrag(held, dayShift = 2, overGrid = true)), zone)).isSameInstanceAs(state)
     }
 }

docs/ARCHITECTURE.md

@@ -391,6 +391,36 @@ gate also covers a snooze re-shown from our own alarm after its calendar was
 switched off. The drawer's filter sheet (`CalendarPrefs.hiddenCalendarIds`) is a
 separate in-app declutter that never touches reminders.
 
+**A channel per calendar (#145).** `ReminderChannels` keeps one notification
+channel per calendar, grouped by account (one that syncs no events only gets
+its channel once something posts on it), so a calendar can be
+muted or given its own sound in the system settings before it ever fires. Every
+scan with reminders on syncs them (skipped when nothing changed): missing
+channels are created, renamed ones updated, and channels of deleted calendars
+removed — but never on an empty snapshot, which is a provider hiccup more often
+than every calendar gone. Switched-off calendars keep theirs, so toggling one
+never cancels a showing reminder or loses its settings. `post` creates a missing
+channel itself, so a reminder never waits on a sync. A new channel copies the sound, vibration and
+importance of the pre-#145 single `reminders` channel, which is deleted once
+nothing showing still sits on it. Settings → Notifications deep-links into the
+system's channel screens for everything but the sound (#340). A sound picked in
+the app (#518) can't be set on an existing channel, so
+`ReminderChannels.setSound` recreates it under a new version
+(`reminders.calendar.<id>.v<n>`), copying everything else from the old one. The
+current version is simply the highest channel that exists, so the new one only
+takes over once written; `SettingsPrefs.reminderChannelVersions` is just a
+high-water mark that keeps ids from being reused (a re-used id would bring back
+the deleted channel's settings). `setSound` leaves the old version to the sync,
+which treats older versions as stale and keeps one while a notification still
+shows on it; `ReminderNotifier.post` resolves and posts under the channel lock
+(`withChannel`), so a pick never moves a channel mid-post.
+Separate from the channels, `SettingsPrefs.mutedReminderCalendarIds` is the in-app per-calendar
+off switch (#272): the scan plans nothing for those calendars (so they arm no
+wake-ups; toggling it re-scans), and `ReminderNotifier.post` checks it again
+for snoozes. The settings screen re-reads `ReminderChannels.status` on every
+resume and marks a calendar "Blocked in system settings" when the app, its
+channel or its account group is switched off there.
+
 Deliberately absent: a fallback to the provider's `EVENT_REMINDER` broadcast.
 Keeping both would double-post wherever the provider works, and Etar's way out —
 a latch that disables its own scheduling once a real broadcast arrives — cannot

fastlane/metadata/android/ar/changelogs/2240299.txt

@@ -0,0 +1,6 @@
+الإصلاحات
+• لم تعد الأحداث المنقولة بسرعة متتالية تضيع: تُحفظ عمليات النقل بالترتيب.
+• تظهر رسالة عند تعذّر حفظ عملية نقل.
+
+التغييرات
+• يعرض عنوان عرض اليوم الشهر.

fastlane/metadata/android/be/changelogs/2240299.txt

@@ -0,0 +1,6 @@
+Выпраўлена
+• Падзеі, перанесеныя хутка адна за адной, больш не губляюцца: пераносы захоўваюцца па чарзе.
+• Паведамленне паказвае, калі перанос не ўдалося захаваць.
+
+Зменена
+• Загаловак дзённага прагляду паказвае месяц.

fastlane/metadata/android/cs-CZ/changelogs/2240299.txt

@@ -0,0 +1,6 @@
+Opraveno
+• Události rychle přesunuté za sebou se už neztrácí: přesuny se ukládají postupně.
+• Zpráva upozorní, když přesun nešel uložit.
+
+Změněno
+• Název denního zobrazení ukazuje měsíc.

fastlane/metadata/android/de-DE/changelogs/2240299.txt

@@ -0,0 +1,6 @@
+Behoben
+• Schnell hintereinander verschobene Termine gehen nicht mehr verloren: Verschiebungen werden der Reihe nach gespeichert.
+• Eine Meldung sagt, wenn eine Verschiebung nicht gespeichert werden konnte.
+
+Geändert
+• Der Titel der Tagesansicht zeigt den Monat.

fastlane/metadata/android/en-US/changelogs/2240299.txt

@@ -0,0 +1,6 @@
+Fixed
+• Events moved in quick succession are no longer lost: moves are saved in order.
+• A message says when a move could not be saved.
+
+Changed
+• The day view title shows the month.

fastlane/metadata/android/es-ES/changelogs/2240299.txt

@@ -0,0 +1,6 @@
+Correcciones
+• Los eventos movidos rápidamente uno tras otro ya no se pierden: los cambios se guardan en orden.
+• Un mensaje avisa cuando no se pudo guardar un cambio.
+
+Cambios
+• El título de la vista diaria muestra el mes.

fastlane/metadata/android/fr-FR/changelogs/2240299.txt

@@ -0,0 +1,6 @@
+Corrections
+• Les événements déplacés rapidement à la suite ne sont plus perdus : les déplacements sont enregistrés dans l’ordre.
+• Un message indique quand un déplacement n’a pas pu être enregistré.
+
+Modifications
+• Le titre de la vue jour affiche le mois.

fastlane/metadata/android/hu-HU/changelogs/2240299.txt

@@ -0,0 +1,6 @@
+Javítva
+• A gyors egymásutánban áthelyezett események többé nem vesznek el: az áthelyezések sorban mentődnek.
+• Üzenet jelzi, ha egy áthelyezést nem sikerült menteni.
+
+Változások
+• A napi nézet címe a hónapot mutatja.

fastlane/metadata/android/it-IT/changelogs/2240299.txt

@@ -0,0 +1,6 @@
+Correzioni
+• Gli eventi spostati rapidamente uno dopo l’altro non vanno più persi: gli spostamenti vengono salvati in ordine.
+• Un messaggio avvisa quando uno spostamento non è stato salvato.
+
+Modifiche
+• Il titolo della vista giornaliera mostra il mese.

fastlane/metadata/android/ja-JP/changelogs/2240299.txt

@@ -0,0 +1,6 @@
+修正
+• 続けてすばやく移動した予定が失われなくなりました。移動は順番に保存されます。
+• 移動を保存できなかったときはメッセージが表示されます。
+
+変更
+• 日表示のタイトルに月が表示されるようになりました。

fastlane/metadata/android/nl-NL/changelogs/2240299.txt

@@ -0,0 +1,6 @@
+Opgelost
+• Snel na elkaar verplaatste afspraken gaan niet meer verloren: verplaatsingen worden op volgorde opgeslagen.
+• Een melding laat weten wanneer een verplaatsing niet kon worden opgeslagen.
+
+Gewijzigd
+• De titel van de dagweergave toont de maand.

fastlane/metadata/android/pl-PL/changelogs/2240299.txt

@@ -0,0 +1,6 @@
+Poprawki
+• Wydarzenia szybko przenoszone jedno po drugim już nie giną: przeniesienia są zapisywane po kolei.
+• Komunikat informuje, gdy przeniesienia nie udało się zapisać.
+
+Zmiany
+• Tytuł widoku dnia pokazuje miesiąc.

fastlane/metadata/android/pt-BR/changelogs/2240299.txt

@@ -0,0 +1,6 @@
+Correções
+• Eventos movidos rapidamente um após o outro não se perdem mais: as mudanças são salvas em ordem.
+• Uma mensagem avisa quando uma mudança não pôde ser salva.
+
+Alterações
+• O título da visualização diária mostra o mês.

fastlane/metadata/android/pt-PT/changelogs/2240299.txt

@@ -0,0 +1,6 @@
+Correções
+• Os eventos movidos rapidamente uns após os outros já não se perdem: as alterações são guardadas por ordem.
+• Uma mensagem avisa quando uma alteração não pôde ser guardada.
+
+Alterações
+• O título da vista diária mostra o mês.

fastlane/metadata/android/ru-RU/changelogs/2240299.txt

@@ -0,0 +1,6 @@
+Исправлено
+• События, быстро перенесённые одно за другим, больше не теряются: переносы сохраняются по очереди.
+• Сообщение показывает, если перенос не удалось сохранить.
+
+Изменено
+• Заголовок дневного вида показывает месяц.

fastlane/metadata/android/sk/changelogs/2240299.txt

@@ -0,0 +1,6 @@
+Opravené
+• Udalosti rýchlo presunuté za sebou sa už nestrácajú: presuny sa ukladajú postupne.
+• Správa upozorní, keď sa presun nepodarilo uložiť.
+
+Zmenené
+• Názov denného zobrazenia ukazuje mesiac.

fastlane/metadata/android/zh-CN/changelogs/2240299.txt

@@ -0,0 +1,6 @@
+修复
+• 快速连续移动的日程不再丢失：移动会按顺序保存。
+• 移动无法保存时会显示提示。
+
+变更
+• 日视图标题显示月份。

fastlane/metadata/android/zh-TW/changelogs/2240299.txt

@@ -0,0 +1,6 @@
+修正
+• 快速連續移動的活動不再遺失：移動會依序儲存。
+• 移動無法儲存時會顯示訊息。
+
+變更
+• 日檢視標題會顯示月份。

gradle/libs.versions.toml

@@ -4,7 +4,7 @@ kotlin = "2.4.20"
 ksp = "2.3.11"
 hilt = "2.60.1"
 coreKtx = "1.19.0"
-appcompat = "1.7.1"
+appcompat = "1.8.0"
 lifecycleRuntime = "2.11.0"
 activityCompose = "1.13.0"
 composeBom = "2026.09.00"
@@ -18,7 +18,7 @@ junitPlatform = "6.1.3"
 truth = "1.4.5"
 androidxJunit = "1.3.0"
 espressoCore = "3.7.0"
-kotlinxDatetime = "0.7.0"
+kotlinxDatetime = "0.8.0-0.6.x-compat"
 kotlinxCoroutines = "1.11.0"
 turbine = "1.2.1"
 hiltNavigationCompose = "1.4.0"