feat(edit): move an event to another calendar (#39)

The calendar row in the editor is now tappable when editing an existing
event: picking a different calendar moves the event there on save, rather
than forcing a delete-and-recreate.

CALENDAR_ID is sync-adapter-owned and can't be updated in place, so the
move is copy+delete: the master row is re-inserted on the target calendar
(preserving UID_2445 so backup dedup and sync identity survive), its
reminders and editable guests are copied, and — for a recurring series —
every exception is replayed against the new master (modified occurrences
via CONTENT_EXCEPTION_URI, cancellations as STATUS_CANCELED). The user's
field edits are then applied with the normal series update. Everything on
the new side is built before the source is deleted (post-before-delete),
with a rollback of the copy on any failure, so a move is all-or-nothing.

A calendar change forces whole-series scope, so it skips the recurring
scope dialog. Managed special-dates calendars stay locked. Colour is not
carried across (a raw/keyed colour may be invalid on the target account),
matching the existing calendar-switch behaviour.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

app/src/test/java/de/jeanlucmakiola/calendula/data/calendar/CalendarRepositoryImplTest.kt

@@ -312,6 +312,46 @@ class CalendarRepositoryImplTest {
         assertThat(fake.updatedEvents).containsExactly(Triple(42L, original, updated))
     }
 
+    @Test
+    fun `moveEvent forwards id, target calendar and both forms`(@TempDir tempDir: Path) = runTest {
+        val fake = FakeCalendarDataSource().apply { nextInsertId = 77L }
+        val repo = CalendarRepositoryImpl(fake, newPrefs(tempDir), newSettings(tempDir), Dispatchers.Unconfined)
+        val original = EventForm(
+            calendarId = 1L,
+            title = "Stand-up",
+            start = LocalDateTime(LocalDate(2026, 6, 12), LocalTime(9, 0)),
+            end = LocalDateTime(LocalDate(2026, 6, 12), LocalTime(9, 15)),
+        )
+        val updated = original.copy(calendarId = 3L)
+
+        val newId = repo.moveEvent(eventId = 42L, targetCalendarId = 3L, original = original, updated = updated)
+
+        assertThat(newId).isEqualTo(77L)
+        assertThat(fake.movedEvents).containsExactly(
+            FakeCalendarDataSource.MovedEvent(42L, 3L, original, updated),
+        )
+    }
+
+    @Test
+    fun `moveEvent propagates write failures`(@TempDir tempDir: Path) = runTest {
+        val fake = FakeCalendarDataSource().apply {
+            writeError = WriteFailedException("insert moved event into calendar id=3")
+        }
+        val repo = CalendarRepositoryImpl(fake, newPrefs(tempDir), newSettings(tempDir), Dispatchers.Unconfined)
+        val form = EventForm(
+            calendarId = 1L,
+            start = LocalDateTime(LocalDate(2026, 6, 12), LocalTime(9, 0)),
+            end = LocalDateTime(LocalDate(2026, 6, 12), LocalTime(10, 0)),
+        )
+
+        try {
+            repo.moveEvent(eventId = 42L, targetCalendarId = 3L, original = form, updated = form.copy(calendarId = 3L))
+            error("Expected WriteFailedException")
+        } catch (expected: WriteFailedException) {
+            assertThat(expected.message).contains("3")
+        }
+    }
+
     @Test
     fun `updateEvent propagates write failures`(@TempDir tempDir: Path) = runTest {
         val fake = FakeCalendarDataSource().apply {

app/src/test/java/de/jeanlucmakiola/calendula/data/calendar/EventWriteMapperTest.kt

@@ -298,4 +298,114 @@ class EventWriteMapperTest {
         assertThat(values).containsEntry(CalendarContract.Events.EVENT_COLOR, null)
         assertThat(values).containsEntry(CalendarContract.Events.EVENT_COLOR_KEY, null)
     }
+
+    // --- buildMovedMasterValues (calendar move: verbatim series copy) ---
+
+    private fun masterSnapshot(
+        isAllDay: Boolean = false,
+        dtStartMillis: Long = 1_781_164_800_000L,
+        dtEndMillis: Long? = 1_781_164_800_000L + 5_400_000L,
+        duration: String? = null,
+        rrule: String? = null,
+        rdate: String? = null,
+        exdate: String? = null,
+    ) = MasterEventSnapshot(
+        title = "Standup",
+        isAllDay = isAllDay,
+        dtStartMillis = dtStartMillis,
+        dtEndMillis = dtEndMillis,
+        duration = duration,
+        rrule = rrule,
+        rdate = rdate,
+        exdate = exdate,
+        timezone = "Europe/Berlin",
+        availability = CalendarContract.Events.AVAILABILITY_BUSY,
+        accessLevel = CalendarContract.Events.ACCESS_DEFAULT,
+        status = CalendarContract.Events.STATUS_CONFIRMED,
+        location = "Room 1",
+        description = "",
+    )
+
+    @Test
+    fun `moved one-off carries target calendar, uid and DTEND but no recurrence`() {
+        val values = buildMovedMasterValues(masterSnapshot(), targetCalendarId = 9L, uid = "u@calendula")
+        assertThat(values[CalendarContract.Events.CALENDAR_ID]).isEqualTo(9L)
+        assertThat(values[CalendarContract.Events.UID_2445]).isEqualTo("u@calendula")
+        assertThat(values[CalendarContract.Events.DTSTART]).isEqualTo(1_781_164_800_000L)
+        assertThat(values[CalendarContract.Events.DTEND]).isEqualTo(1_781_164_800_000L + 5_400_000L)
+        assertThat(values).doesNotContainKey(CalendarContract.Events.RRULE)
+        assertThat(values).doesNotContainKey(CalendarContract.Events.DURATION)
+        // Empty description clears explicitly; a raw/keyed colour is never copied
+        // (may be invalid on the target account — the copy inherits its colour).
+        assertThat(values).containsEntry(CalendarContract.Events.DESCRIPTION, null)
+        assertThat(values).doesNotContainKey(CalendarContract.Events.EVENT_COLOR)
+        assertThat(values).doesNotContainKey(CalendarContract.Events.EVENT_COLOR_KEY)
+    }
+
+    @Test
+    fun `moved series preserves the recurrence skeleton as RRULE plus DURATION`() {
+        val values = buildMovedMasterValues(
+            masterSnapshot(dtEndMillis = null, duration = "P5400S", rrule = "FREQ=WEEKLY", exdate = "20260618T080000Z"),
+            targetCalendarId = 9L,
+            uid = "u@calendula",
+        )
+        assertThat(values[CalendarContract.Events.RRULE]).isEqualTo("FREQ=WEEKLY")
+        assertThat(values[CalendarContract.Events.DURATION]).isEqualTo("P5400S")
+        assertThat(values[CalendarContract.Events.EXDATE]).isEqualTo("20260618T080000Z")
+        // Recurring rows never carry DTEND (the provider's invariant).
+        assertThat(values).doesNotContainKey(CalendarContract.Events.DTEND)
+    }
+
+    @Test
+    fun `moved series without a stored duration derives it from DTEND`() {
+        val values = buildMovedMasterValues(
+            masterSnapshot(duration = null, rrule = "FREQ=DAILY"),
+            targetCalendarId = 9L,
+            uid = "u@calendula",
+        )
+        assertThat(values[CalendarContract.Events.DURATION]).isEqualTo("P5400S")
+    }
+
+    // --- buildCopiedExceptionValues (calendar move: exception replay) ---
+
+    private fun exceptionSnapshot(
+        isCancelled: Boolean = false,
+        duration: String? = null,
+        // Occurrence starts one hour into the day and runs 30 minutes.
+        dtEndMillis: Long? = 1_781_164_800_000L + 3_600_000L + 1_800_000L,
+    ) = ExceptionRowSnapshot(
+        exceptionEventId = 42L,
+        originalInstanceMillis = 1_781_164_800_000L,
+        isCancelled = isCancelled,
+        status = if (isCancelled) CalendarContract.Events.STATUS_CANCELED else CalendarContract.Events.STATUS_CONFIRMED,
+        title = "Moved occurrence",
+        isAllDay = false,
+        dtStartMillis = 1_781_164_800_000L + 3_600_000L,
+        dtEndMillis = dtEndMillis,
+        duration = duration,
+        timezone = "Europe/Berlin",
+        availability = CalendarContract.Events.AVAILABILITY_BUSY,
+        accessLevel = CalendarContract.Events.ACCESS_DEFAULT,
+        location = "",
+        description = "Notes",
+    )
+
+    @Test
+    fun `copied modified occurrence carries the original instance and DURATION not DTEND`() {
+        val values = buildCopiedExceptionValues(exceptionSnapshot())
+        assertThat(values[CalendarContract.Events.ORIGINAL_INSTANCE_TIME])
+            .isEqualTo(1_781_164_800_000L)
+        assertThat(values[CalendarContract.Events.TITLE]).isEqualTo("Moved occurrence")
+        assertThat(values[CalendarContract.Events.DTSTART]).isEqualTo(1_781_164_800_000L + 3_600_000L)
+        // 30-minute occurrence derived from DTEND, written as DURATION only.
+        assertThat(values[CalendarContract.Events.DURATION]).isEqualTo("P1800S")
+        assertThat(values).doesNotContainKey(CalendarContract.Events.DTEND)
+        assertThat(values).containsEntry(CalendarContract.Events.EVENT_LOCATION, null)
+    }
+
+    @Test
+    fun `copied modified occurrence keeps a stored duration verbatim`() {
+        val values = buildCopiedExceptionValues(exceptionSnapshot(duration = "P900S", dtEndMillis = null))
+        assertThat(values[CalendarContract.Events.DURATION]).isEqualTo("P900S")
+    }
 }

app/src/test/java/de/jeanlucmakiola/calendula/data/calendar/FakeCalendarDataSource.kt

@@ -34,6 +34,13 @@ internal class FakeCalendarDataSource : CalendarDataSource {
 
     val insertedForms = mutableListOf<EventForm>()
     val updatedEvents = mutableListOf<Triple<Long, EventForm, EventForm>>()
+    data class MovedEvent(
+        val eventId: Long,
+        val targetCalendarId: Long,
+        val original: EventForm,
+        val updated: EventForm,
+    )
+    val movedEvents = mutableListOf<MovedEvent>()
     val updatedOccurrences = mutableListOf<Triple<Long, Long, EventForm>>()
     val updatedFromOccurrences = mutableListOf<Triple<Long, Long, EventForm>>()
     val deletedEventIds = mutableListOf<Long>()
@@ -116,6 +123,19 @@ internal class FakeCalendarDataSource : CalendarDataSource {
         allDayReminderTimes += allDayReminderTimeMinutes
     }
 
+    override fun moveEvent(
+        eventId: Long,
+        targetCalendarId: Long,
+        original: EventForm,
+        updated: EventForm,
+        allDayReminderTimeMinutes: Int,
+    ): Long {
+        writeError?.let { throw it }
+        movedEvents += MovedEvent(eventId, targetCalendarId, original, updated)
+        allDayReminderTimes += allDayReminderTimeMinutes
+        return nextInsertId
+    }
+
     override fun updateOccurrence(
         eventId: Long,
         beginMillis: Long,

app/src/test/java/de/jeanlucmakiola/calendula/ui/edit/EventEditViewModelTest.kt

@@ -0,0 +1,158 @@
+package de.jeanlucmakiola.calendula.ui.edit
+
+import androidx.datastore.core.DataStore
+import androidx.datastore.preferences.core.PreferenceDataStoreFactory
+import androidx.datastore.preferences.core.Preferences
+import com.google.common.truth.Truth.assertThat
+import de.jeanlucmakiola.calendula.data.calendar.CalendarRepositoryImpl
+import de.jeanlucmakiola.calendula.data.calendar.FakeCalendarDataSource
+import de.jeanlucmakiola.calendula.data.prefs.CalendarPrefs
+import de.jeanlucmakiola.calendula.data.prefs.SettingsPrefs
+import de.jeanlucmakiola.calendula.domain.CalendarSource
+import de.jeanlucmakiola.calendula.domain.EventDetail
+import de.jeanlucmakiola.calendula.domain.EventInstance
+import kotlinx.coroutines.CoroutineDispatcher
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.test.UnconfinedTestDispatcher
+import kotlinx.coroutines.test.advanceUntilIdle
+import kotlinx.coroutines.test.resetMain
+import kotlinx.coroutines.test.runTest
+import kotlinx.coroutines.test.setMain
+import kotlinx.coroutines.Dispatchers
+import org.junit.jupiter.api.AfterEach
+import org.junit.jupiter.api.BeforeEach
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.io.TempDir
+import java.nio.file.Path
+import kotlin.time.Instant
+
+/**
+ * Focuses on the save-time branch that decides between an in-place update and a
+ * calendar *move* (copy+delete). The provider-level move itself is verified
+ * on-device; here the fake records which repository call the ViewModel chose.
+ */
+@OptIn(ExperimentalCoroutinesApi::class)
+class EventEditViewModelTest {
+
+    private val dispatcher = UnconfinedTestDispatcher()
+
+    @BeforeEach fun setUp() = Dispatchers.setMain(dispatcher)
+    @AfterEach fun tearDown() = Dispatchers.resetMain()
+
+    private val beginMillis = 1_781_164_800_000L
+    private val endMillis = beginMillis + 3_600_000L
+
+    private fun cal(id: Long): CalendarSource = CalendarSource(
+        id = id, displayName = "Cal $id", accountName = "acc@local", accountType = "LOCAL",
+        color = 0xFF112233.toInt(), isVisibleInSystem = true, canModifyContents = true,
+    )
+
+    private fun detail(calendarId: Long, rrule: String? = null): EventDetail = EventDetail(
+        instance = EventInstance(
+            instanceId = 42L, eventId = 42L, calendarId = calendarId, title = "Standup",
+            start = Instant.fromEpochMilliseconds(beginMillis),
+            end = Instant.fromEpochMilliseconds(endMillis),
+            isAllDay = false, color = 0xFF000000.toInt(), location = null,
+        ),
+        description = null, organizer = null, attendees = emptyList(), rrule = rrule,
+    )
+
+    // Pin the DataStore's scope to the test dispatcher so a settings write (e.g.
+    // last-used calendar) completes under advanceUntilIdle instead of on a real
+    // IO thread the virtual clock can't observe.
+    private fun prefs(tempDir: Path): CalendarPrefs = CalendarPrefs(
+        PreferenceDataStoreFactory.create(
+            scope = CoroutineScope(dispatcher),
+            produceFile = { tempDir.resolve("vm_prefs.preferences_pb").toFile() },
+        ),
+    )
+
+    private fun settings(tempDir: Path): SettingsPrefs = SettingsPrefs(
+        PreferenceDataStoreFactory.create(
+            scope = CoroutineScope(dispatcher),
+            produceFile = { tempDir.resolve("vm_settings.preferences_pb").toFile() },
+        ),
+    )
+
+    private fun viewModel(
+        tempDir: Path,
+        fake: FakeCalendarDataSource,
+    ): EventEditViewModel {
+        val p = prefs(tempDir)
+        val s = settings(tempDir)
+        val repo = CalendarRepositoryImpl(fake, p, s, dispatcher as CoroutineDispatcher)
+        return EventEditViewModel(repo, p, s, dispatcher)
+    }
+
+    /** Keep [EventEditViewModel.state] hot so it computes while the test drives it. */
+    private fun CoroutineScope.activate(vm: EventEditViewModel): Job = launch { vm.state.collect {} }
+
+    @Test
+    fun `changing the calendar routes the save through a move, not an update`(
+        @TempDir tempDir: Path,
+    ) = runTest(dispatcher) {
+        val fake = FakeCalendarDataSource().apply {
+            calendarsResult = listOf(cal(1L), cal(2L))
+            eventDetailResult = { detail(calendarId = 1L) }
+            nextInsertId = 99L
+        }
+        val vm = viewModel(tempDir, fake)
+        val job = activate(vm)
+
+        vm.openForEdit(eventId = 42L, beginMillis = beginMillis, endMillis = endMillis)
+        vm.setCalendar(2L)
+        vm.save()
+        advanceUntilIdle()
+
+        assertThat(fake.movedEvents).hasSize(1)
+        assertThat(fake.movedEvents.single().eventId).isEqualTo(42L)
+        assertThat(fake.movedEvents.single().targetCalendarId).isEqualTo(2L)
+        assertThat(fake.updatedEvents).isEmpty()
+        assertThat(vm.state.value?.saveState).isEqualTo(SaveUiState.Saved)
+        job.cancel()
+    }
+
+    @Test
+    fun `moving a recurring event skips the scope dialog`(@TempDir tempDir: Path) = runTest(dispatcher) {
+        val fake = FakeCalendarDataSource().apply {
+            calendarsResult = listOf(cal(1L), cal(2L))
+            eventDetailResult = { detail(calendarId = 1L, rrule = "FREQ=WEEKLY") }
+        }
+        val vm = viewModel(tempDir, fake)
+        val job = activate(vm)
+
+        vm.openForEdit(eventId = 42L, beginMillis = beginMillis, endMillis = endMillis)
+        vm.setCalendar(2L)
+        vm.save()
+        advanceUntilIdle()
+
+        // No AwaitingScope park: a move is inherently whole-series.
+        assertThat(vm.state.value?.saveState).isEqualTo(SaveUiState.Saved)
+        assertThat(fake.movedEvents).hasSize(1)
+        job.cancel()
+    }
+
+    @Test
+    fun `editing a recurring event without moving still asks for the scope`(
+        @TempDir tempDir: Path,
+    ) = runTest(dispatcher) {
+        val fake = FakeCalendarDataSource().apply {
+            calendarsResult = listOf(cal(1L), cal(2L))
+            eventDetailResult = { detail(calendarId = 1L, rrule = "FREQ=WEEKLY") }
+        }
+        val vm = viewModel(tempDir, fake)
+        val job = activate(vm)
+
+        vm.openForEdit(eventId = 42L, beginMillis = beginMillis, endMillis = endMillis)
+        vm.setTitle("Renamed")
+        vm.save()
+        advanceUntilIdle()
+
+        assertThat(vm.state.value?.saveState).isEqualTo(SaveUiState.AwaitingScope)
+        assertThat(fake.movedEvents).isEmpty()
+        job.cancel()
+    }
+}