feat(write): event creation — form screen, FAB, last-used calendar (v1.2)

Second slice of milestone 2 (write support):

- EventForm domain model + problems() validation (end-before-start,
  no-calendar; blank titles and instant events stay legal)
- Full-screen EventEditScreen: title, all-day switch, M3 date/time pickers
  (moving the start preserves the duration), calendar picker limited to
  writable calendars, location, description. Save validates, requests the
  WRITE upgrade contextually, and closes on success
- Calendar preselection: explicit pick > last-used (CalendarPrefs) > first
  writable calendar
- insertEvent in the data source; EventWriteMapper (JVM-tested) normalises
  all-day events to UTC midnights with exclusive DTEND, timed events to the
  device zone
- CalendarFabColumn shared by month/week/day: persistent "+" FAB anchored on
  the visible day, jump-to-today pill stacked above it
- Tests: EventForm validation, write-time mapping (incl. DST-safe epoch
  check), repository createEvent delegation/error propagation

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

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

@@ -13,8 +13,10 @@ import dagger.hilt.android.qualifiers.ApplicationContext
 import de.jeanlucmakiola.calendula.domain.Attendee
 import de.jeanlucmakiola.calendula.domain.CalendarSource
 import de.jeanlucmakiola.calendula.domain.EventDetail
+import de.jeanlucmakiola.calendula.domain.EventForm
 import de.jeanlucmakiola.calendula.domain.EventInstance
 import de.jeanlucmakiola.calendula.domain.Reminder
+import java.time.ZoneId
 import javax.inject.Inject
 import javax.inject.Singleton
 
@@ -31,6 +33,9 @@ interface CalendarDataSource {
     fun instances(beginMillis: Long, endMillis: Long): List<EventInstance>
     fun eventDetail(eventId: Long): EventDetail?
 
+    /** Insert a new event; returns the new `Events._ID`. */
+    fun insertEvent(form: EventForm): Long
+
     /** Delete the whole event (for recurring events: the entire series). */
     fun deleteEvent(eventId: Long)
 
@@ -85,6 +90,28 @@ class AndroidCalendarDataSource @Inject constructor(
         }
     }
 
+    override fun insertEvent(form: EventForm): Long {
+        val times = form.toWriteTimes(ZoneId.systemDefault())
+        val values = ContentValues().apply {
+            put(
+                CalendarContract.Events.CALENDAR_ID,
+                requireNotNull(form.calendarId) { "EventForm.calendarId is required" },
+            )
+            put(CalendarContract.Events.TITLE, form.title.trim())
+            put(CalendarContract.Events.ALL_DAY, if (form.isAllDay) 1 else 0)
+            put(CalendarContract.Events.DTSTART, times.dtStartMillis)
+            put(CalendarContract.Events.DTEND, times.dtEndMillis)
+            put(CalendarContract.Events.EVENT_TIMEZONE, times.timezone)
+            form.location.trim().takeIf { it.isNotEmpty() }
+                ?.let { put(CalendarContract.Events.EVENT_LOCATION, it) }
+            form.description.trim().takeIf { it.isNotEmpty() }
+                ?.let { put(CalendarContract.Events.DESCRIPTION, it) }
+        }
+        val uri = resolver.insert(CalendarContract.Events.CONTENT_URI, values)
+            ?: throw WriteFailedException("insert event into calendar id=${form.calendarId}")
+        return ContentUris.parseId(uri)
+    }
+
     override fun deleteEvent(eventId: Long) {
         val deleted = resolver.delete(
             ContentUris.withAppendedId(CalendarContract.Events.CONTENT_URI, eventId),

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

@@ -2,6 +2,7 @@ package de.jeanlucmakiola.calendula.data.calendar
 
 import de.jeanlucmakiola.calendula.domain.CalendarSource
 import de.jeanlucmakiola.calendula.domain.EventDetail
+import de.jeanlucmakiola.calendula.domain.EventForm
 import de.jeanlucmakiola.calendula.domain.EventInstance
 import kotlinx.coroutines.flow.Flow
 import kotlin.time.Instant
@@ -11,6 +12,9 @@ interface CalendarRepository {
     fun instances(range: ClosedRange<Instant>): Flow<List<EventInstance>>
     suspend fun eventDetail(eventId: Long): EventDetail
 
+    /** Create a new event from a validated form; returns the new `Events._ID`. */
+    suspend fun createEvent(form: EventForm): Long
+
     /** Delete the whole event (for recurring events: the entire series). */
     suspend fun deleteEvent(eventId: Long)
 

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

@@ -4,6 +4,7 @@ import de.jeanlucmakiola.calendula.data.di.IoDispatcher
 import de.jeanlucmakiola.calendula.data.prefs.CalendarPrefs
 import de.jeanlucmakiola.calendula.domain.CalendarSource
 import de.jeanlucmakiola.calendula.domain.EventDetail
+import de.jeanlucmakiola.calendula.domain.EventForm
 import de.jeanlucmakiola.calendula.domain.EventInstance
 import kotlinx.coroutines.CoroutineDispatcher
 import kotlinx.coroutines.flow.Flow
@@ -69,6 +70,10 @@ class CalendarRepositoryImpl @Inject constructor(
         dataSource.eventDetail(eventId) ?: throw NoSuchEventException(eventId)
     }
 
+    override suspend fun createEvent(form: EventForm): Long = withContext(io) {
+        dataSource.insertEvent(form)
+    }
+
     override suspend fun deleteEvent(eventId: Long) = withContext(io) {
         dataSource.deleteEvent(eventId)
     }

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

@@ -0,0 +1,35 @@
+package de.jeanlucmakiola.calendula.data.calendar
+
+import de.jeanlucmakiola.calendula.domain.EventForm
+import kotlinx.datetime.toJavaLocalDate
+import kotlinx.datetime.toJavaLocalDateTime
+import java.time.ZoneId
+import java.time.ZoneOffset
+
+/** Provider-ready DTSTART / DTEND / EVENT_TIMEZONE for an event write. */
+internal data class EventWriteTimes(
+    val dtStartMillis: Long,
+    val dtEndMillis: Long,
+    val timezone: String,
+)
+
+/**
+ * All-day events live at UTC midnights with an exclusive DTEND (the
+ * CalendarContract convention — a one-day event ends at the next midnight);
+ * timed events resolve their wall-clock values in [zone].
+ */
+internal fun EventForm.toWriteTimes(zone: ZoneId): EventWriteTimes = if (isAllDay) {
+    EventWriteTimes(
+        dtStartMillis = start.date.toJavaLocalDate()
+            .atStartOfDay(ZoneOffset.UTC).toInstant().toEpochMilli(),
+        dtEndMillis = end.date.toJavaLocalDate().plusDays(1)
+            .atStartOfDay(ZoneOffset.UTC).toInstant().toEpochMilli(),
+        timezone = "UTC",
+    )
+} else {
+    EventWriteTimes(
+        dtStartMillis = start.toJavaLocalDateTime().atZone(zone).toInstant().toEpochMilli(),
+        dtEndMillis = end.toJavaLocalDateTime().atZone(zone).toInstant().toEpochMilli(),
+        timezone = zone.id,
+    )
+}

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

@@ -3,6 +3,7 @@ package de.jeanlucmakiola.calendula.data.prefs
 import androidx.datastore.core.DataStore
 import androidx.datastore.preferences.core.Preferences
 import androidx.datastore.preferences.core.edit
+import androidx.datastore.preferences.core.longPreferencesKey
 import androidx.datastore.preferences.core.stringPreferencesKey
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.map
@@ -38,7 +39,20 @@ class CalendarPrefs @Inject constructor(
         }
     }
 
+    /**
+     * The calendar the user last created an event in; preselected in the
+     * event form. Null until the first event is created.
+     */
+    val lastUsedCalendarId: Flow<Long?> = store.data.map { prefs ->
+        prefs[LAST_USED_CALENDAR_KEY]
+    }
+
+    suspend fun setLastUsedCalendarId(id: Long) {
+        store.edit { prefs -> prefs[LAST_USED_CALENDAR_KEY] = id }
+    }
+
     companion object {
         internal val HIDDEN_IDS_KEY = stringPreferencesKey("hidden_calendar_ids")
+        internal val LAST_USED_CALENDAR_KEY = longPreferencesKey("last_used_calendar_id")
     }
 }

app/src/main/java/de/jeanlucmakiola/calendula/domain/EventForm.kt

@@ -0,0 +1,35 @@
+package de.jeanlucmakiola.calendula.domain
+
+import kotlinx.datetime.LocalDateTime
+
+/**
+ * User input for creating an event (and, from v1.3, editing one). Times are
+ * wall-clock values in the device zone; the data layer translates them to
+ * provider millis (all-day events normalise to UTC midnights there).
+ */
+data class EventForm(
+    val calendarId: Long?,
+    val title: String = "",
+    val isAllDay: Boolean = false,
+    val start: LocalDateTime,
+    val end: LocalDateTime,
+    val location: String = "",
+    val description: String = "",
+)
+
+enum class EventFormProblem {
+    /** No target calendar — none picked and no writable calendar exists. */
+    NoCalendar,
+    EndBeforeStart,
+}
+
+/**
+ * Validation; an empty set means the form can be saved. A blank title is
+ * allowed (display falls back to "(No title)", matching the provider), and a
+ * zero-length timed event is allowed (spec §8: instant events exist).
+ */
+fun EventForm.problems(): Set<EventFormProblem> = buildSet {
+    if (calendarId == null) add(EventFormProblem.NoCalendar)
+    val endsTooEarly = if (isAllDay) end.date < start.date else end < start
+    if (endsTooEarly) add(EventFormProblem.EndBeforeStart)
+}

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

@@ -19,6 +19,7 @@ import de.jeanlucmakiola.calendula.ui.common.CalendarView
 import de.jeanlucmakiola.calendula.ui.common.rememberCalendarSlideSpec
 import de.jeanlucmakiola.calendula.ui.day.DayScreen
 import de.jeanlucmakiola.calendula.ui.detail.EventDetailScreen
+import de.jeanlucmakiola.calendula.ui.edit.EventEditScreen
 import de.jeanlucmakiola.calendula.ui.month.MonthScreen
 import de.jeanlucmakiola.calendula.ui.settings.SettingsScreen
 import de.jeanlucmakiola.calendula.ui.week.WeekScreen
@@ -66,6 +67,15 @@ fun CalendarHost(modifier: Modifier = Modifier) {
     var showSettings by rememberSaveable { mutableStateOf(false) }
     val onOpenSettings = { showSettings = true }
 
+    // Event form (v1.2 create) — same held-key pattern as the detail screen:
+    // [heldCreateIso] keeps the prefill date alive through the slide-out.
+    var createDateIso by rememberSaveable { mutableStateOf<String?>(null) }
+    var heldCreateIso by remember { mutableStateOf<String?>(null) }
+    val onCreateEvent: (LocalDate) -> Unit = { date ->
+        heldCreateIso = date.toString()
+        createDateIso = date.toString()
+    }
+
     val slideSpec = rememberCalendarSlideSpec()
 
     Box(modifier = modifier.fillMaxSize()) {
@@ -75,12 +85,14 @@ fun CalendarHost(modifier: Modifier = Modifier) {
                 onSelectView = onSelectView,
                 onEventClick = onEventClick,
                 onOpenSettings = onOpenSettings,
+                onCreateEvent = onCreateEvent,
             )
             CalendarView.Day -> DayScreen(
                 selectedView = view,
                 onSelectView = onSelectView,
                 onEventClick = onEventClick,
                 onOpenSettings = onOpenSettings,
+                onCreateEvent = onCreateEvent,
                 initialDateIso = pendingDayIso,
             )
             CalendarView.Month -> MonthScreen(
@@ -88,6 +100,7 @@ fun CalendarHost(modifier: Modifier = Modifier) {
                 onSelectView = onSelectView,
                 onOpenDay = onOpenDay,
                 onOpenSettings = onOpenSettings,
+                onCreateEvent = onCreateEvent,
             )
         }
 
@@ -108,6 +121,20 @@ fun CalendarHost(modifier: Modifier = Modifier) {
             }
         }
 
+        // Event form (v1.2) — full-screen destination, slides over the calendar.
+        AnimatedVisibility(
+            visible = createDateIso != null,
+            enter = slideInHorizontally(slideSpec) { it } + fadeIn(),
+            exit = slideOutHorizontally(slideSpec) { it } + fadeOut(),
+        ) {
+            (createDateIso ?: heldCreateIso)?.let { iso ->
+                EventEditScreen(
+                    initialDateIso = iso,
+                    onClose = { createDateIso = null },
+                )
+            }
+        }
+
         // Settings (M4) — full-screen destination, slides over the calendar.
         AnimatedVisibility(
             visible = showSettings,

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

@@ -0,0 +1,55 @@
+package de.jeanlucmakiola.calendula.ui.common
+
+import androidx.compose.animation.AnimatedVisibility
+import androidx.compose.animation.scaleIn
+import androidx.compose.animation.scaleOut
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Column
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.filled.Add
+import androidx.compose.material.icons.filled.Refresh
+import androidx.compose.material3.ExtendedFloatingActionButton
+import androidx.compose.material3.FloatingActionButton
+import androidx.compose.material3.Icon
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.unit.dp
+import de.jeanlucmakiola.calendula.R
+
+/**
+ * The FAB stack shared by the three calendar views: a persistent "+" to
+ * create an event, with the jump-to-today pill appearing above it whenever
+ * the view isn't anchored on today.
+ */
+@Composable
+fun CalendarFabColumn(
+    todayVisible: Boolean,
+    todayText: String,
+    onToday: () -> Unit,
+    onCreate: () -> Unit,
+) {
+    Column(
+        horizontalAlignment = Alignment.End,
+        verticalArrangement = Arrangement.spacedBy(16.dp),
+    ) {
+        AnimatedVisibility(
+            visible = todayVisible,
+            enter = scaleIn(),
+            exit = scaleOut(),
+        ) {
+            ExtendedFloatingActionButton(
+                onClick = onToday,
+                icon = { Icon(Icons.Default.Refresh, contentDescription = null) },
+                text = { Text(todayText) },
+            )
+        }
+        FloatingActionButton(onClick = onCreate) {
+            Icon(
+                imageVector = Icons.Default.Add,
+                contentDescription = stringResource(R.string.event_edit_new_title),
+            )
+        }
+    }
+}

app/src/main/java/de/jeanlucmakiola/calendula/ui/day/DayScreen.kt

@@ -1,11 +1,8 @@
 package de.jeanlucmakiola.calendula.ui.day
 
 import androidx.compose.animation.AnimatedContent
-import androidx.compose.animation.AnimatedVisibility
 import androidx.compose.animation.animateColorAsState
 import androidx.compose.animation.core.animateDpAsState
-import androidx.compose.animation.scaleIn
-import androidx.compose.animation.scaleOut
 import androidx.compose.foundation.background
 import androidx.compose.foundation.clickable
 import androidx.compose.foundation.gestures.detectHorizontalDragGestures
@@ -28,12 +25,10 @@ import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.foundation.verticalScroll
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.filled.Menu
-import androidx.compose.material.icons.filled.Refresh
 import androidx.compose.material3.Card
 import androidx.compose.material3.CardDefaults
 import androidx.compose.material3.DrawerValue
 import androidx.compose.material3.ExperimentalMaterial3Api
-import androidx.compose.material3.ExtendedFloatingActionButton
 import androidx.compose.material3.Icon
 import androidx.compose.material3.IconButton
 import androidx.compose.material3.MaterialTheme
@@ -72,6 +67,7 @@ import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import de.jeanlucmakiola.calendula.R
 import de.jeanlucmakiola.calendula.domain.EventInstance
 import de.jeanlucmakiola.calendula.ui.common.CalendarDrawer
+import de.jeanlucmakiola.calendula.ui.common.CalendarFabColumn
 import de.jeanlucmakiola.calendula.ui.common.CalendarFailure
 import de.jeanlucmakiola.calendula.ui.common.CalendarView
 import de.jeanlucmakiola.calendula.ui.common.ViewSwitcherPill
@@ -108,6 +104,7 @@ fun DayScreen(
     onSelectView: (CalendarView) -> Unit,
     onEventClick: (EventInstance) -> Unit,
     onOpenSettings: () -> Unit,
+    onCreateEvent: (LocalDate) -> Unit,
     modifier: Modifier = Modifier,
     initialDateIso: String? = null,
     viewModel: DayViewModel = hiltViewModel(),
@@ -172,17 +169,12 @@ fun DayScreen(
                 )
             },
             floatingActionButton = {
-                AnimatedVisibility(
+                CalendarFabColumn(
-                    visible = !isOnToday,
+                    todayVisible = !isOnToday,
-                    enter = scaleIn(),
+                    todayText = stringResource(R.string.day_today_action),
-                    exit = scaleOut(),
+                    onToday = jumpToToday,
-                ) {
+                    onCreate = { onCreateEvent(date) },
-                    ExtendedFloatingActionButton(
+                )
-                        onClick = jumpToToday,
-                        icon = { Icon(Icons.Default.Refresh, contentDescription = null) },
-                        text = { Text(stringResource(R.string.day_today_action)) },
-                    )
-                }
             },
         ) { innerPadding ->
             DayContent(

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

@@ -0,0 +1,550 @@
+package de.jeanlucmakiola.calendula.ui.edit
+
+import android.Manifest
+import android.content.pm.PackageManager
+import androidx.activity.compose.BackHandler
+import androidx.activity.compose.rememberLauncherForActivityResult
+import androidx.activity.result.contract.ActivityResultContracts
+import androidx.compose.foundation.clickable
+import androidx.compose.foundation.isSystemInDarkTheme
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.size
+import androidx.compose.foundation.layout.width
+import androidx.compose.foundation.rememberScrollState
+import androidx.compose.foundation.selection.selectable
+import androidx.compose.foundation.shape.RoundedCornerShape
+import androidx.compose.foundation.verticalScroll
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.automirrored.filled.Notes
+import androidx.compose.material.icons.filled.CalendarMonth
+import androidx.compose.material.icons.filled.Close
+import androidx.compose.material.icons.filled.Place
+import androidx.compose.material.icons.filled.Schedule
+import androidx.compose.material3.AlertDialog
+import androidx.compose.material3.Button
+import androidx.compose.material3.DatePicker
+import androidx.compose.material3.DatePickerDialog
+import androidx.compose.material3.ExperimentalMaterial3Api
+import androidx.compose.material3.HorizontalDivider
+import androidx.compose.material3.Icon
+import androidx.compose.material3.IconButton
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.OutlinedTextField
+import androidx.compose.material3.RadioButton
+import androidx.compose.material3.Scaffold
+import androidx.compose.material3.SnackbarHost
+import androidx.compose.material3.SnackbarHostState
+import androidx.compose.material3.Switch
+import androidx.compose.material3.Text
+import androidx.compose.material3.TextButton
+import androidx.compose.material3.TextField
+import androidx.compose.material3.TextFieldDefaults
+import androidx.compose.material3.TimePicker
+import androidx.compose.material3.TopAppBar
+import androidx.compose.material3.TopAppBarDefaults
+import androidx.compose.material3.rememberDatePickerState
+import androidx.compose.material3.rememberTimePickerState
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.LaunchedEffect
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+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.graphics.Color
+import androidx.compose.ui.platform.LocalContext
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.semantics.Role
+import androidx.compose.ui.unit.dp
+import androidx.core.content.ContextCompat
+import androidx.hilt.navigation.compose.hiltViewModel
+import androidx.lifecycle.compose.collectAsStateWithLifecycle
+import de.jeanlucmakiola.calendula.R
+import de.jeanlucmakiola.calendula.domain.CalendarSource
+import de.jeanlucmakiola.calendula.domain.EventFormProblem
+import de.jeanlucmakiola.calendula.ui.common.currentLocale
+import de.jeanlucmakiola.calendula.ui.common.pastelize
+import kotlinx.datetime.LocalDate
+import kotlinx.datetime.LocalDateTime
+import kotlinx.datetime.LocalTime
+import kotlinx.datetime.TimeZone
+import kotlinx.datetime.toJavaLocalDate
+import kotlinx.datetime.toJavaLocalTime
+import kotlinx.datetime.toLocalDateTime
+import java.time.format.DateTimeFormatter
+import java.time.format.FormatStyle
+import java.util.Locale
+import kotlin.time.Clock
+
+/**
+ * Full-screen event form (v1.2: create only). Opens prefilled from the FAB's
+ * anchor date; Save validates, writes via the repository, and closes. The
+ * calendar picker offers only writable calendars.
+ */
+@OptIn(ExperimentalMaterial3Api::class)
+@Composable
+fun EventEditScreen(
+    initialDateIso: String?,
+    onClose: () -> Unit,
+    viewModel: EventEditViewModel = hiltViewModel(),
+) {
+    LaunchedEffect(initialDateIso) {
+        val date = initialDateIso?.let { runCatching { LocalDate.parse(it) }.getOrNull() }
+            ?: Clock.System.now().toLocalDateTime(TimeZone.currentSystemDefault()).date
+        viewModel.openNew(date)
+    }
+    val state by viewModel.state.collectAsStateWithLifecycle()
+
+    // The form is intentionally forgotten on every close (cancel or save) so
+    // the next FAB tap starts clean; it survives rotation because openNew
+    // no-ops while a form is set.
+    val close = {
+        viewModel.reset()
+        onClose()
+    }
+    BackHandler(onBack = close)
+
+    val context = LocalContext.current
+    val snackbarHostState = remember { SnackbarHostState() }
+
+    // Contextual WRITE_CALENDAR upgrade for v1.0 installs, like delete.
+    val writePermissionLauncher = rememberLauncherForActivityResult(
+        contract = ActivityResultContracts.RequestPermission(),
+    ) { granted ->
+        if (granted) viewModel.save()
+    }
+    val onSaveClick = {
+        val granted = ContextCompat.checkSelfPermission(
+            context,
+            Manifest.permission.WRITE_CALENDAR,
+        ) == PackageManager.PERMISSION_GRANTED
+        if (granted) {
+            viewModel.save()
+        } else {
+            writePermissionLauncher.launch(Manifest.permission.WRITE_CALENDAR)
+        }
+    }
+
+    val saveFailedMessage = stringResource(R.string.event_edit_save_failed)
+    val writeDeniedMessage = stringResource(R.string.event_edit_write_denied)
+    LaunchedEffect(state?.saveState) {
+        when (state?.saveState) {
+            SaveUiState.Saved -> close()
+            SaveUiState.Failed -> {
+                viewModel.consumeSaveResult()
+                snackbarHostState.showSnackbar(saveFailedMessage)
+            }
+            SaveUiState.NeedsPermission -> {
+                viewModel.consumeSaveResult()
+                snackbarHostState.showSnackbar(writeDeniedMessage)
+            }
+            SaveUiState.Idle, SaveUiState.Saving, null -> Unit
+        }
+    }
+
+    Scaffold(
+        snackbarHost = { SnackbarHost(snackbarHostState) },
+        topBar = {
+            TopAppBar(
+                title = { Text(stringResource(R.string.event_edit_new_title)) },
+                navigationIcon = {
+                    IconButton(onClick = close) {
+                        Icon(
+                            imageVector = Icons.Default.Close,
+                            contentDescription = stringResource(R.string.event_edit_close),
+                        )
+                    }
+                },
+                actions = {
+                    Button(
+                        onClick = onSaveClick,
+                        enabled = state != null && state?.saveState != SaveUiState.Saving,
+                        modifier = Modifier.padding(end = 12.dp),
+                    ) {
+                        Text(stringResource(R.string.event_edit_save))
+                    }
+                },
+                colors = TopAppBarDefaults.topAppBarColors(
+                    containerColor = MaterialTheme.colorScheme.surface,
+                ),
+            )
+        },
+    ) { innerPadding ->
+        state?.let { s ->
+            EventEditContent(
+                state = s,
+                viewModel = viewModel,
+                modifier = Modifier
+                    .fillMaxSize()
+                    .padding(innerPadding),
+            )
+        }
+    }
+}
+
+private enum class PickerTarget { StartDate, StartTime, EndDate, EndTime }
+
+@Composable
+private fun EventEditContent(
+    state: EventEditUiState,
+    viewModel: EventEditViewModel,
+    modifier: Modifier = Modifier,
+) {
+    val form = state.form
+    val locale = currentLocale()
+    var picker by remember { mutableStateOf<PickerTarget?>(null) }
+    var showCalendarPicker by rememberSaveable { mutableStateOf(false) }
+
+    Column(
+        modifier = modifier
+            .verticalScroll(rememberScrollState())
+            .padding(start = 24.dp, end = 24.dp, top = 8.dp, bottom = 40.dp),
+    ) {
+        // Title: a large borderless field, MD3 "create" idiom.
+        TextField(
+            value = form.title,
+            onValueChange = viewModel::setTitle,
+            placeholder = {
+                Text(
+                    text = stringResource(R.string.event_edit_title_hint),
+                    style = MaterialTheme.typography.headlineSmall,
+                )
+            },
+            textStyle = MaterialTheme.typography.headlineSmall,
+            singleLine = true,
+            colors = TextFieldDefaults.colors(
+                focusedContainerColor = Color.Transparent,
+                unfocusedContainerColor = Color.Transparent,
+            ),
+            modifier = Modifier.fillMaxWidth(),
+        )
+
+        Spacer(Modifier.height(16.dp))
+        HorizontalDivider()
+        Spacer(Modifier.height(16.dp))
+
+        // All-day toggle.
+        Row(
+            verticalAlignment = Alignment.CenterVertically,
+            modifier = Modifier.fillMaxWidth(),
+        ) {
+            Icon(
+                imageVector = Icons.Default.Schedule,
+                contentDescription = null,
+                tint = MaterialTheme.colorScheme.onSurfaceVariant,
+                modifier = Modifier.size(24.dp),
+            )
+            Spacer(Modifier.width(16.dp))
+            Text(
+                text = stringResource(R.string.event_detail_all_day),
+                style = MaterialTheme.typography.bodyLarge,
+                modifier = Modifier.weight(1f),
+            )
+            Switch(checked = form.isAllDay, onCheckedChange = viewModel::setAllDay)
+        }
+
+        Spacer(Modifier.height(8.dp))
+
+        // Start / end rows: tappable date + (for timed events) time labels.
+        DateTimeRow(
+            label = stringResource(R.string.event_edit_starts),
+            dateTime = form.start,
+            isAllDay = form.isAllDay,
+            locale = locale,
+            onDateClick = { picker = PickerTarget.StartDate },
+            onTimeClick = { picker = PickerTarget.StartTime },
+        )
+        DateTimeRow(
+            label = stringResource(R.string.event_edit_ends),
+            dateTime = form.end,
+            isAllDay = form.isAllDay,
+            locale = locale,
+            onDateClick = { picker = PickerTarget.EndDate },
+            onTimeClick = { picker = PickerTarget.EndTime },
+            isError = EventFormProblem.EndBeforeStart in state.problems,
+        )
+        if (EventFormProblem.EndBeforeStart in state.problems) {
+            Text(
+                text = stringResource(R.string.event_edit_error_end_before_start),
+                style = MaterialTheme.typography.bodySmall,
+                color = MaterialTheme.colorScheme.error,
+                modifier = Modifier.padding(start = 40.dp, top = 2.dp),
+            )
+        }
+
+        Spacer(Modifier.height(16.dp))
+        HorizontalDivider()
+        Spacer(Modifier.height(16.dp))
+
+        // Calendar picker row.
+        val selectedCalendar = state.calendars.firstOrNull { it.id == form.calendarId }
+        val dark = isSystemInDarkTheme()
+        Row(
+            verticalAlignment = Alignment.CenterVertically,
+            modifier = Modifier
+                .fillMaxWidth()
+                .clickable(enabled = state.calendars.isNotEmpty()) { showCalendarPicker = true }
+                .padding(vertical = 8.dp),
+        ) {
+            Icon(
+                imageVector = Icons.Default.CalendarMonth,
+                contentDescription = stringResource(R.string.event_detail_calendar),
+                tint = selectedCalendar?.let { pastelize(it.color, dark) }
+                    ?: MaterialTheme.colorScheme.onSurfaceVariant,
+                modifier = Modifier.size(24.dp),
+            )
+            Spacer(Modifier.width(16.dp))
+            Column(modifier = Modifier.weight(1f)) {
+                Text(
+                    text = selectedCalendar?.displayName
+                        ?: stringResource(R.string.event_edit_error_no_calendar),
+                    style = MaterialTheme.typography.bodyLarge,
+                    color = if (selectedCalendar == null) {
+                        MaterialTheme.colorScheme.error
+                    } else {
+                        Color.Unspecified
+                    },
+                )
+                selectedCalendar?.accountName?.takeIf { it.isNotBlank() }?.let { account ->
+                    Text(
+                        text = account,
+                        style = MaterialTheme.typography.bodySmall,
+                        color = MaterialTheme.colorScheme.onSurfaceVariant,
+                    )
+                }
+            }
+        }
+
+        Spacer(Modifier.height(16.dp))
+        HorizontalDivider()
+        Spacer(Modifier.height(16.dp))
+
+        OutlinedTextField(
+            value = form.location,
+            onValueChange = viewModel::setLocation,
+            label = { Text(stringResource(R.string.event_detail_location)) },
+            leadingIcon = { Icon(Icons.Default.Place, contentDescription = null) },
+            singleLine = true,
+            modifier = Modifier.fillMaxWidth(),
+        )
+        Spacer(Modifier.height(12.dp))
+        OutlinedTextField(
+            value = form.description,
+            onValueChange = viewModel::setDescription,
+            label = { Text(stringResource(R.string.event_detail_description)) },
+            leadingIcon = { Icon(Icons.AutoMirrored.Filled.Notes, contentDescription = null) },
+            minLines = 3,
+            modifier = Modifier.fillMaxWidth(),
+        )
+    }
+
+    when (picker) {
+        PickerTarget.StartDate -> DatePickerAlert(
+            initial = form.start.date,
+            onConfirm = { viewModel.setStartDate(it); picker = null },
+            onDismiss = { picker = null },
+        )
+        PickerTarget.EndDate -> DatePickerAlert(
+            initial = form.end.date,
+            onConfirm = { viewModel.setEndDate(it); picker = null },
+            onDismiss = { picker = null },
+        )
+        PickerTarget.StartTime -> TimePickerAlert(
+            initial = form.start.time,
+            onConfirm = { viewModel.setStartTime(it); picker = null },
+            onDismiss = { picker = null },
+        )
+        PickerTarget.EndTime -> TimePickerAlert(
+            initial = form.end.time,
+            onConfirm = { viewModel.setEndTime(it); picker = null },
+            onDismiss = { picker = null },
+        )
+        null -> Unit
+    }
+
+    if (showCalendarPicker) {
+        CalendarPickerDialog(
+            calendars = state.calendars,
+            selectedId = form.calendarId,
+            onSelect = {
+                viewModel.setCalendar(it)
+                showCalendarPicker = false
+            },
+            onDismiss = { showCalendarPicker = false },
+        )
+    }
+}
+
+/** One schedule row: label, then tappable date and (unless all-day) time. */
+@Composable
+private fun DateTimeRow(
+    label: String,
+    dateTime: LocalDateTime,
+    isAllDay: Boolean,
+    locale: Locale,
+    onDateClick: () -> Unit,
+    onTimeClick: () -> Unit,
+    isError: Boolean = false,
+) {
+    val dateFormat = remember(locale) {
+        DateTimeFormatter.ofLocalizedDate(FormatStyle.MEDIUM).withLocale(locale)
+    }
+    val timeFormat = remember(locale) {
+        DateTimeFormatter.ofLocalizedTime(FormatStyle.SHORT).withLocale(locale)
+    }
+    val contentColor = if (isError) {
+        MaterialTheme.colorScheme.error
+    } else {
+        MaterialTheme.colorScheme.onSurface
+    }
+    Row(
+        verticalAlignment = Alignment.CenterVertically,
+        modifier = Modifier
+            .fillMaxWidth()
+            .padding(start = 40.dp, top = 8.dp, bottom = 8.dp),
+    ) {
+        Text(
+            text = label,
+            style = MaterialTheme.typography.bodyLarge,
+            modifier = Modifier.weight(1f),
+        )
+        Text(
+            text = dateFormat.format(dateTime.date.toJavaLocalDate()),
+            style = MaterialTheme.typography.bodyLarge,
+            color = contentColor,
+            modifier = Modifier
+                .clickable(onClick = onDateClick)
+                .padding(8.dp),
+        )
+        if (!isAllDay) {
+            Text(
+                text = timeFormat.format(dateTime.time.toJavaLocalTime()),
+                style = MaterialTheme.typography.bodyLarge,
+                color = contentColor,
+                modifier = Modifier
+                    .clickable(onClick = onTimeClick)
+                    .padding(8.dp),
+            )
+        }
+    }
+}
+
+@OptIn(ExperimentalMaterial3Api::class)
+@Composable
+private fun DatePickerAlert(
+    initial: LocalDate,
+    onConfirm: (LocalDate) -> Unit,
+    onDismiss: () -> Unit,
+) {
+    // DatePicker speaks UTC-midnight millis; epoch-day arithmetic keeps the
+    // conversion zone-proof in both directions.
+    val state = rememberDatePickerState(
+        initialSelectedDateMillis = initial.toEpochDays() * MILLIS_PER_DAY,
+    )
+    DatePickerDialog(
+        onDismissRequest = onDismiss,
+        confirmButton = {
+            TextButton(
+                onClick = {
+                    state.selectedDateMillis?.let { millis ->
+                        onConfirm(LocalDate.fromEpochDays((millis / MILLIS_PER_DAY).toInt()))
+                    }
+                },
+            ) { Text(stringResource(R.string.dialog_ok)) }
+        },
+        dismissButton = {
+            TextButton(onClick = onDismiss) { Text(stringResource(R.string.dialog_cancel)) }
+        },
+    ) {
+        DatePicker(state = state)
+    }
+}
+
+@OptIn(ExperimentalMaterial3Api::class)
+@Composable
+private fun TimePickerAlert(
+    initial: LocalTime,
+    onConfirm: (LocalTime) -> Unit,
+    onDismiss: () -> Unit,
+) {
+    val state = rememberTimePickerState(
+        initialHour = initial.hour,
+        initialMinute = initial.minute,
+    )
+    AlertDialog(
+        onDismissRequest = onDismiss,
+        confirmButton = {
+            TextButton(onClick = { onConfirm(LocalTime(state.hour, state.minute)) }) {
+                Text(stringResource(R.string.dialog_ok))
+            }
+        },
+        dismissButton = {
+            TextButton(onClick = onDismiss) { Text(stringResource(R.string.dialog_cancel)) }
+        },
+        text = { TimePicker(state = state) },
+    )
+}
+
+@Composable
+private fun CalendarPickerDialog(
+    calendars: List<CalendarSource>,
+    selectedId: Long?,
+    onSelect: (Long) -> Unit,
+    onDismiss: () -> Unit,
+) {
+    val dark = isSystemInDarkTheme()
+    AlertDialog(
+        onDismissRequest = onDismiss,
+        title = { Text(stringResource(R.string.event_detail_calendar)) },
+        text = {
+            Column {
+                calendars.forEach { calendar ->
+                    Row(
+                        verticalAlignment = Alignment.CenterVertically,
+                        modifier = Modifier
+                            .fillMaxWidth()
+                            .selectable(
+                                selected = calendar.id == selectedId,
+                                role = Role.RadioButton,
+                                onClick = { onSelect(calendar.id) },
+                            )
+                            .padding(vertical = 8.dp),
+                    ) {
+                        RadioButton(selected = calendar.id == selectedId, onClick = null)
+                        Spacer(Modifier.width(8.dp))
+                        Icon(
+                            imageVector = Icons.Default.CalendarMonth,
+                            contentDescription = null,
+                            tint = pastelize(calendar.color, dark),
+                            modifier = Modifier.size(20.dp),
+                        )
+                        Spacer(Modifier.width(8.dp))
+                        Column {
+                            Text(calendar.displayName, style = MaterialTheme.typography.bodyLarge)
+                            if (calendar.accountName.isNotBlank()) {
+                                Text(
+                                    text = calendar.accountName,
+                                    style = MaterialTheme.typography.bodySmall,
+                                    color = MaterialTheme.colorScheme.onSurfaceVariant,
+                                )
+                            }
+                        }
+                    }
+                }
+            }
+        },
+        confirmButton = {
+            TextButton(onClick = onDismiss) { Text(stringResource(R.string.dialog_cancel)) }
+        },
+    )
+}
+
+private const val MILLIS_PER_DAY = 86_400_000L

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

@@ -0,0 +1,29 @@
+package de.jeanlucmakiola.calendula.ui.edit
+
+import de.jeanlucmakiola.calendula.domain.CalendarSource
+import de.jeanlucmakiola.calendula.domain.EventForm
+import de.jeanlucmakiola.calendula.domain.EventFormProblem
+
+/**
+ * UI state for the event form (v1.2: create; v1.3 reuses it for edit). Null
+ * form means the screen hasn't been opened yet.
+ */
+data class EventEditUiState(
+    /** The form with its calendar id resolved (picked > last used > first writable). */
+    val form: EventForm,
+    /** Calendars that accept writes — the only valid targets. */
+    val calendars: List<CalendarSource>,
+    /** Validation problems; empty until a save was attempted. */
+    val problems: Set<EventFormProblem>,
+    val saveState: SaveUiState,
+)
+
+/** One-shot state of a save request, mirroring DeleteUiState on the detail screen. */
+sealed interface SaveUiState {
+    data object Idle : SaveUiState
+    data object Saving : SaveUiState
+    data object Saved : SaveUiState
+    /** WRITE_CALENDAR was revoked between the tap and the provider call. */
+    data object NeedsPermission : SaveUiState
+    data object Failed : SaveUiState
+}

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

@@ -0,0 +1,160 @@
+package de.jeanlucmakiola.calendula.ui.edit
+
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewModelScope
+import dagger.hilt.android.lifecycle.HiltViewModel
+import de.jeanlucmakiola.calendula.data.calendar.CalendarRepository
+import de.jeanlucmakiola.calendula.data.di.IoDispatcher
+import de.jeanlucmakiola.calendula.data.prefs.CalendarPrefs
+import de.jeanlucmakiola.calendula.domain.EventForm
+import de.jeanlucmakiola.calendula.domain.problems
+import kotlinx.coroutines.CoroutineDispatcher
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.SharingStarted
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.catch
+import kotlinx.coroutines.flow.combine
+import kotlinx.coroutines.flow.flowOn
+import kotlinx.coroutines.flow.map
+import kotlinx.coroutines.flow.stateIn
+import kotlinx.coroutines.launch
+import kotlinx.datetime.LocalDate
+import kotlinx.datetime.LocalDateTime
+import kotlinx.datetime.LocalTime
+import kotlinx.datetime.TimeZone
+import kotlinx.datetime.toInstant
+import kotlinx.datetime.toLocalDateTime
+import kotlin.coroutines.cancellation.CancellationException
+import kotlin.time.Clock
+import kotlin.time.Duration.Companion.hours
+import kotlin.time.Instant
+import javax.inject.Inject
+
+/**
+ * Holds the event form being composed. The form's calendar id resolves to
+ * (user pick > last used > first writable); the resolved value is what the UI
+ * shows and what gets saved.
+ */
+@HiltViewModel
+class EventEditViewModel @Inject constructor(
+    private val repository: CalendarRepository,
+    private val prefs: CalendarPrefs,
+    @IoDispatcher private val io: CoroutineDispatcher,
+) : ViewModel() {
+
+    private val _form = MutableStateFlow<EventForm?>(null)
+    private val _saveState = MutableStateFlow<SaveUiState>(SaveUiState.Idle)
+    // Problems stay hidden until the first save attempt, so a half-filled
+    // form isn't already shouting errors.
+    private val _showProblems = MutableStateFlow(false)
+
+    val state: StateFlow<EventEditUiState?> = combine(
+        _form,
+        repository.calendars()
+            .map { calendars -> calendars.filter { it.canModifyContents } }
+            .catch { emit(emptyList()) },
+        prefs.lastUsedCalendarId,
+        _saveState,
+        _showProblems,
+    ) { form, writable, lastUsed, saveState, showProblems ->
+        if (form == null) return@combine null
+        val resolvedId = form.calendarId
+            ?: lastUsed?.takeIf { id -> writable.any { it.id == id } }
+            ?: writable.firstOrNull()?.id
+        val resolved = form.copy(calendarId = resolvedId)
+        EventEditUiState(
+            form = resolved,
+            calendars = writable,
+            problems = if (showProblems) resolved.problems() else emptySet(),
+            saveState = saveState,
+        )
+    }
+        .flowOn(io)
+        .stateIn(
+            scope = viewModelScope,
+            started = SharingStarted.WhileSubscribed(5_000L),
+            initialValue = null,
+        )
+
+    /**
+     * Initialise a fresh form for a new event on [date]. No-op when a form is
+     * already open, so user input survives configuration changes; [reset]
+     * clears it when the screen closes.
+     */
+    fun openNew(date: LocalDate) {
+        if (_form.value != null) return
+        val zone = TimeZone.currentSystemDefault()
+        val now = Clock.System.now()
+        val start = if (date == now.toLocalDateTime(zone).date) {
+            // Today: the next full hour (may roll into tomorrow before midnight).
+            val hourMillis = 3_600_000L
+            val rounded = (now.toEpochMilliseconds() / hourMillis + 1) * hourMillis
+            Instant.fromEpochMilliseconds(rounded).toLocalDateTime(zone)
+        } else {
+            LocalDateTime(date, LocalTime(9, 0))
+        }
+        val end = (start.toInstant(zone) + 1.hours).toLocalDateTime(zone)
+        _form.value = EventForm(calendarId = null, start = start, end = end)
+    }
+
+    /** Forget the open form; the next [openNew] starts clean. */
+    fun reset() {
+        _form.value = null
+        _saveState.value = SaveUiState.Idle
+        _showProblems.value = false
+    }
+
+    fun setTitle(value: String) = update { it.copy(title = value) }
+    fun setLocation(value: String) = update { it.copy(location = value) }
+    fun setDescription(value: String) = update { it.copy(description = value) }
+    fun setAllDay(value: Boolean) = update { it.copy(isAllDay = value) }
+    fun setCalendar(id: Long) = update { it.copy(calendarId = id) }
+
+    /** Moving the start drags the end along, preserving the duration. */
+    fun setStartDate(date: LocalDate) = moveStart { LocalDateTime(date, it.time) }
+    fun setStartTime(time: LocalTime) = moveStart { LocalDateTime(it.date, time) }
+    fun setEndDate(date: LocalDate) = update { it.copy(end = LocalDateTime(date, it.end.time)) }
+    fun setEndTime(time: LocalTime) = update { it.copy(end = LocalDateTime(it.end.date, time)) }
+
+    /** Validate and write. Terminal results land in [saveState]. */
+    fun save() {
+        val current = state.value ?: return
+        if (current.saveState == SaveUiState.Saving) return
+        val form = current.form
+        if (form.problems().isNotEmpty()) {
+            _showProblems.value = true
+            return
+        }
+        viewModelScope.launch {
+            _saveState.value = SaveUiState.Saving
+            _saveState.value = try {
+                repository.createEvent(form)
+                prefs.setLastUsedCalendarId(requireNotNull(form.calendarId))
+                SaveUiState.Saved
+            } catch (e: CancellationException) {
+                throw e
+            } catch (e: SecurityException) {
+                SaveUiState.NeedsPermission
+            } catch (e: Exception) {
+                SaveUiState.Failed
+            }
+        }
+    }
+
+    /** Reset [saveState] after the screen handled a terminal result. */
+    fun consumeSaveResult() {
+        _saveState.value = SaveUiState.Idle
+    }
+
+    private fun moveStart(transform: (LocalDateTime) -> LocalDateTime) = update { form ->
+        val zone = TimeZone.currentSystemDefault()
+        val newStart = transform(form.start)
+        val duration = form.end.toInstant(zone) - form.start.toInstant(zone)
+        val newEnd = (newStart.toInstant(zone) + duration).toLocalDateTime(zone)
+        form.copy(start = newStart, end = newEnd)
+    }
+
+    private inline fun update(block: (EventForm) -> EventForm) {
+        _form.value = _form.value?.let(block)
+    }
+}

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

@@ -1,10 +1,7 @@
 package de.jeanlucmakiola.calendula.ui.month
 
 import androidx.compose.animation.AnimatedContent
-import androidx.compose.animation.AnimatedVisibility
 import androidx.compose.animation.core.animateFloatAsState
-import androidx.compose.animation.scaleIn
-import androidx.compose.animation.scaleOut
 import androidx.compose.foundation.background
 import androidx.compose.foundation.gestures.detectHorizontalDragGestures
 import androidx.compose.foundation.interaction.MutableInteractionSource
@@ -23,13 +20,11 @@ import androidx.compose.foundation.layout.size
 import androidx.compose.foundation.shape.CircleShape
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.filled.Menu
-import androidx.compose.material.icons.filled.Refresh
 import androidx.compose.material3.Card
 import androidx.compose.material3.CardDefaults
 import androidx.compose.material3.DrawerValue
 import androidx.compose.material3.ExperimentalMaterial3Api
 import androidx.compose.material3.ExperimentalMaterial3ExpressiveApi
-import androidx.compose.material3.ExtendedFloatingActionButton
 import androidx.compose.material3.Icon
 import androidx.compose.material3.IconButton
 import androidx.compose.material3.MaterialTheme
@@ -62,6 +57,7 @@ import androidx.hilt.navigation.compose.hiltViewModel
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import de.jeanlucmakiola.calendula.R
 import de.jeanlucmakiola.calendula.ui.common.CalendarDrawer
+import de.jeanlucmakiola.calendula.ui.common.CalendarFabColumn
 import de.jeanlucmakiola.calendula.ui.common.CalendarFailure
 import de.jeanlucmakiola.calendula.ui.common.CalendarView
 import de.jeanlucmakiola.calendula.ui.common.ViewSwitcherPill
@@ -74,8 +70,11 @@ import kotlinx.coroutines.launch
 import kotlinx.datetime.DateTimeUnit
 import kotlinx.datetime.DayOfWeek
 import kotlinx.datetime.LocalDate
+import kotlinx.datetime.TimeZone
 import kotlinx.datetime.YearMonth
 import kotlinx.datetime.plus
+import kotlinx.datetime.toLocalDateTime
+import kotlin.time.Clock
 import java.time.format.TextStyle as JavaTextStyle
 import java.util.Locale
 
@@ -86,6 +85,7 @@ fun MonthScreen(
     onSelectView: (CalendarView) -> Unit,
     onOpenDay: (LocalDate) -> Unit,
     onOpenSettings: () -> Unit,
+    onCreateEvent: (LocalDate) -> Unit,
     modifier: Modifier = Modifier,
     viewModel: MonthViewModel = hiltViewModel(),
 ) {
@@ -147,17 +147,20 @@ fun MonthScreen(
                 )
             },
             floatingActionButton = {
-                AnimatedVisibility(
+                CalendarFabColumn(
-                    visible = !isOnCurrentMonth,
+                    todayVisible = !isOnCurrentMonth,
-                    enter = scaleIn(),
+                    todayText = stringResource(R.string.month_today_action),
-                    exit = scaleOut(),
+                    onToday = jumpToToday,
-                ) {
+                    onCreate = {
-                    ExtendedFloatingActionButton(
+                        // Anchor on today when its month is shown, else the 1st.
-                        onClick = jumpToToday,
+                        val today = Clock.System.now()
-                        icon = { Icon(Icons.Default.Refresh, contentDescription = null) },
+                            .toLocalDateTime(TimeZone.currentSystemDefault()).date
-                        text = { Text(stringResource(R.string.month_today_action)) },
+                        onCreateEvent(
-                    )
+                            if (isOnCurrentMonth) today
-                }
+                            else LocalDate(month.year, month.month, 1),
+                        )
+                    },
+                )
             },
         ) { innerPadding ->
             Column(

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

@@ -1,11 +1,8 @@
 package de.jeanlucmakiola.calendula.ui.week
 
 import androidx.compose.animation.AnimatedContent
-import androidx.compose.animation.AnimatedVisibility
 import androidx.compose.animation.animateColorAsState
 import androidx.compose.animation.core.animateDpAsState
-import androidx.compose.animation.scaleIn
-import androidx.compose.animation.scaleOut
 import androidx.compose.foundation.background
 import androidx.compose.foundation.clickable
 import androidx.compose.foundation.gestures.detectHorizontalDragGestures
@@ -31,12 +28,10 @@ import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.foundation.verticalScroll
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.filled.Menu
-import androidx.compose.material.icons.filled.Refresh
 import androidx.compose.material3.Card
 import androidx.compose.material3.CardDefaults
 import androidx.compose.material3.DrawerValue
 import androidx.compose.material3.ExperimentalMaterial3Api
-import androidx.compose.material3.ExtendedFloatingActionButton
 import androidx.compose.material3.Icon
 import androidx.compose.material3.IconButton
 import androidx.compose.material3.MaterialTheme
@@ -77,6 +72,7 @@ import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import de.jeanlucmakiola.calendula.R
 import de.jeanlucmakiola.calendula.domain.EventInstance
 import de.jeanlucmakiola.calendula.ui.common.CalendarDrawer
+import de.jeanlucmakiola.calendula.ui.common.CalendarFabColumn
 import de.jeanlucmakiola.calendula.ui.common.CalendarFailure
 import de.jeanlucmakiola.calendula.ui.common.CalendarView
 import de.jeanlucmakiola.calendula.ui.common.ViewSwitcherPill
@@ -88,7 +84,10 @@ import de.jeanlucmakiola.calendula.ui.common.pastelize
 import kotlinx.coroutines.flow.first
 import kotlinx.coroutines.launch
 import kotlinx.datetime.LocalDate
+import kotlinx.datetime.TimeZone
 import kotlinx.datetime.plus
+import kotlinx.datetime.toLocalDateTime
+import kotlin.time.Clock
 import java.time.format.TextStyle as JavaTextStyle
 import java.util.Locale
 import kotlin.math.roundToInt
@@ -113,6 +112,7 @@ fun WeekScreen(
     onSelectView: (CalendarView) -> Unit,
     onEventClick: (EventInstance) -> Unit,
     onOpenSettings: () -> Unit,
+    onCreateEvent: (LocalDate) -> Unit,
     modifier: Modifier = Modifier,
     viewModel: WeekViewModel = hiltViewModel(),
 ) {
@@ -174,17 +174,17 @@ fun WeekScreen(
                 )
             },
             floatingActionButton = {
-                AnimatedVisibility(
+                CalendarFabColumn(
-                    visible = !isOnCurrentWeek,
+                    todayVisible = !isOnCurrentWeek,
-                    enter = scaleIn(),
+                    todayText = stringResource(R.string.week_today_action),
-                    exit = scaleOut(),
+                    onToday = jumpToToday,
-                ) {
+                    onCreate = {
-                    ExtendedFloatingActionButton(
+                        // Anchor on today when it's in view, else the week's first day.
-                        onClick = jumpToToday,
+                        val today = Clock.System.now()
-                        icon = { Icon(Icons.Default.Refresh, contentDescription = null) },
+                            .toLocalDateTime(TimeZone.currentSystemDefault()).date
-                        text = { Text(stringResource(R.string.week_today_action)) },
+                        onCreateEvent(if (isOnCurrentWeek) today else weekStart)
-                    )
+                    },
-                }
+                )
             },
         ) { innerPadding ->
             WeekContent(

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

@@ -54,6 +54,19 @@
     <string name="event_delete_failed">Termin konnte nicht gelöscht werden</string>
     <string name="event_delete_write_denied">Calendula braucht Schreibzugriff, um Termine zu löschen</string>
     <string name="dialog_cancel">Abbrechen</string>
+    <string name="dialog_ok">OK</string>
+
+    <!-- Termin-Formular (v1.2 Erstellen) -->
+    <string name="event_edit_new_title">Neuer Termin</string>
+    <string name="event_edit_close">Schließen</string>
+    <string name="event_edit_save">Speichern</string>
+    <string name="event_edit_title_hint">Titel hinzufügen</string>
+    <string name="event_edit_starts">Beginn</string>
+    <string name="event_edit_ends">Ende</string>
+    <string name="event_edit_error_end_before_start">Endet vor dem Beginn</string>
+    <string name="event_edit_error_no_calendar">Kein beschreibbarer Kalender verfügbar</string>
+    <string name="event_edit_save_failed">Termin konnte nicht gespeichert werden</string>
+    <string name="event_edit_write_denied">Calendula braucht Schreibzugriff, um Termine zu erstellen</string>
     <string name="event_detail_all_day">Ganztägig</string>
     <string name="event_detail_calendar">Kalender</string>
     <string name="event_detail_calendar_unknown">Unbekannter Kalender</string>

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

@@ -55,6 +55,19 @@
     <string name="event_delete_failed">Couldn\'t delete the event</string>
     <string name="event_delete_write_denied">Calendula needs write access to delete events</string>
     <string name="dialog_cancel">Cancel</string>
+    <string name="dialog_ok">OK</string>
+
+    <!-- Event form (v1.2 create) -->
+    <string name="event_edit_new_title">New event</string>
+    <string name="event_edit_close">Close</string>
+    <string name="event_edit_save">Save</string>
+    <string name="event_edit_title_hint">Add title</string>
+    <string name="event_edit_starts">Starts</string>
+    <string name="event_edit_ends">Ends</string>
+    <string name="event_edit_error_end_before_start">Ends before it starts</string>
+    <string name="event_edit_error_no_calendar">No writable calendar available</string>
+    <string name="event_edit_save_failed">Couldn\'t save the event</string>
+    <string name="event_edit_write_denied">Calendula needs write access to create events</string>
     <string name="event_detail_all_day">All day</string>
     <string name="event_detail_calendar">Calendar</string>
     <string name="event_detail_calendar_unknown">Unknown calendar</string>

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

@@ -7,8 +7,12 @@ import app.cash.turbine.test
 import com.google.common.truth.Truth.assertThat
 import de.jeanlucmakiola.calendula.data.prefs.CalendarPrefs
 import de.jeanlucmakiola.calendula.domain.CalendarSource
+import de.jeanlucmakiola.calendula.domain.EventForm
 import de.jeanlucmakiola.calendula.domain.EventInstance
 import kotlinx.coroutines.Dispatchers
+import kotlinx.datetime.LocalDate
+import kotlinx.datetime.LocalDateTime
+import kotlinx.datetime.LocalTime
 import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.test.UnconfinedTestDispatcher
 import kotlinx.coroutines.test.runTest
@@ -157,6 +161,43 @@ class CalendarRepositoryImplTest {
         }
     }
 
+    @Test
+    fun `createEvent delegates and returns the new id`(@TempDir tempDir: Path) = runTest {
+        val fake = FakeCalendarDataSource().apply { nextInsertId = 77L }
+        val repo = CalendarRepositoryImpl(fake, newPrefs(tempDir), Dispatchers.Unconfined)
+        val form = 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 id = repo.createEvent(form)
+
+        assertThat(id).isEqualTo(77L)
+        assertThat(fake.insertedForms).containsExactly(form)
+    }
+
+    @Test
+    fun `createEvent propagates write failures`(@TempDir tempDir: Path) = runTest {
+        val fake = FakeCalendarDataSource().apply {
+            writeError = WriteFailedException("insert event")
+        }
+        val repo = CalendarRepositoryImpl(fake, newPrefs(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.createEvent(form)
+            error("Expected WriteFailedException")
+        } catch (expected: WriteFailedException) {
+            assertThat(expected.message).contains("insert")
+        }
+    }
+
     @Test
     fun `deleteEvent delegates to the data source`(@TempDir tempDir: Path) = runTest {
         val fake = FakeCalendarDataSource()

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

@@ -0,0 +1,49 @@
+package de.jeanlucmakiola.calendula.data.calendar
+
+import com.google.common.truth.Truth.assertThat
+import de.jeanlucmakiola.calendula.domain.EventForm
+import kotlinx.datetime.LocalDate
+import kotlinx.datetime.LocalDateTime
+import kotlinx.datetime.LocalTime
+import org.junit.jupiter.api.Test
+import java.time.ZoneId
+
+class EventWriteMapperTest {
+
+    private val berlin: ZoneId = ZoneId.of("Europe/Berlin")
+
+    private fun form(
+        isAllDay: Boolean = false,
+        start: LocalDateTime = LocalDateTime(LocalDate(2026, 6, 11), LocalTime(10, 0)),
+        end: LocalDateTime = LocalDateTime(LocalDate(2026, 6, 11), LocalTime(11, 30)),
+    ): EventForm = EventForm(calendarId = 1L, isAllDay = isAllDay, start = start, end = end)
+
+    @Test
+    fun `timed event resolves wall clock in the given zone`() {
+        val times = form().toWriteTimes(berlin)
+        // 2026-06-11 is CEST (UTC+2): 10:00 local == 08:00Z.
+        assertThat(times.dtStartMillis).isEqualTo(1_781_164_800_000L)
+        assertThat(times.dtEndMillis - times.dtStartMillis).isEqualTo(90L * 60L * 1000L)
+        assertThat(times.timezone).isEqualTo("Europe/Berlin")
+    }
+
+    @Test
+    fun `all-day event lives at UTC midnights with exclusive end`() {
+        val times = form(isAllDay = true).toWriteTimes(berlin)
+        assertThat(times.timezone).isEqualTo("UTC")
+        assertThat(times.dtStartMillis % 86_400_000L).isEqualTo(0L)
+        // Single-day all-day event: DTEND is the NEXT UTC midnight.
+        assertThat(times.dtEndMillis - times.dtStartMillis).isEqualTo(86_400_000L)
+    }
+
+    @Test
+    fun `multi-day all-day event spans every covered day`() {
+        val times = form(
+            isAllDay = true,
+            start = LocalDateTime(LocalDate(2026, 6, 11), LocalTime(0, 0)),
+            end = LocalDateTime(LocalDate(2026, 6, 13), LocalTime(0, 0)),
+        ).toWriteTimes(berlin)
+        // 11th, 12th, 13th inclusive = 3 days.
+        assertThat(times.dtEndMillis - times.dtStartMillis).isEqualTo(3L * 86_400_000L)
+    }
+}

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

@@ -2,6 +2,7 @@ package de.jeanlucmakiola.calendula.data.calendar
 
 import de.jeanlucmakiola.calendula.domain.CalendarSource
 import de.jeanlucmakiola.calendula.domain.EventDetail
+import de.jeanlucmakiola.calendula.domain.EventForm
 import de.jeanlucmakiola.calendula.domain.EventInstance
 
 /**
@@ -15,7 +16,10 @@ internal class FakeCalendarDataSource : CalendarDataSource {
     var eventDetailResult: (Long) -> EventDetail? = { null }
     /** Set to make the next write call throw. */
     var writeError: Exception? = null
+    /** Id returned by the next [insertEvent]. */
+    var nextInsertId: Long = 100L
 
+    val insertedForms = mutableListOf<EventForm>()
     val deletedEventIds = mutableListOf<Long>()
     val deletedOccurrences = mutableListOf<Pair<Long, Long>>()
 
@@ -26,6 +30,12 @@ internal class FakeCalendarDataSource : CalendarDataSource {
         instancesResult(beginMillis, endMillis)
     override fun eventDetail(eventId: Long): EventDetail? = eventDetailResult(eventId)
 
+    override fun insertEvent(form: EventForm): Long {
+        writeError?.let { throw it }
+        insertedForms += form
+        return nextInsertId
+    }
+
     override fun deleteEvent(eventId: Long) {
         writeError?.let { throw it }
         deletedEventIds += eventId

app/src/test/java/de/jeanlucmakiola/calendula/domain/EventFormTest.kt

@@ -0,0 +1,72 @@
+package de.jeanlucmakiola.calendula.domain
+
+import com.google.common.truth.Truth.assertThat
+import kotlinx.datetime.LocalDate
+import kotlinx.datetime.LocalDateTime
+import kotlinx.datetime.LocalTime
+import org.junit.jupiter.api.Test
+
+class EventFormTest {
+
+    private fun form(
+        calendarId: Long? = 1L,
+        isAllDay: Boolean = false,
+        start: LocalDateTime = LocalDateTime(LocalDate(2026, 6, 11), LocalTime(10, 0)),
+        end: LocalDateTime = LocalDateTime(LocalDate(2026, 6, 11), LocalTime(11, 0)),
+    ): EventForm = EventForm(calendarId = calendarId, isAllDay = isAllDay, start = start, end = end)
+
+    @Test
+    fun `valid timed form has no problems`() {
+        assertThat(form().problems()).isEmpty()
+    }
+
+    @Test
+    fun `missing calendar is a problem`() {
+        assertThat(form(calendarId = null).problems())
+            .containsExactly(EventFormProblem.NoCalendar)
+    }
+
+    @Test
+    fun `timed end before start is a problem`() {
+        val bad = form(end = LocalDateTime(LocalDate(2026, 6, 11), LocalTime(9, 0)))
+        assertThat(bad.problems()).containsExactly(EventFormProblem.EndBeforeStart)
+    }
+
+    @Test
+    fun `zero-length timed event is allowed`() {
+        val instant = form(end = LocalDateTime(LocalDate(2026, 6, 11), LocalTime(10, 0)))
+        assertThat(instant.problems()).isEmpty()
+    }
+
+    @Test
+    fun `all-day single day is allowed even though times match`() {
+        val allDay = form(
+            isAllDay = true,
+            start = LocalDateTime(LocalDate(2026, 6, 11), LocalTime(0, 0)),
+            end = LocalDateTime(LocalDate(2026, 6, 11), LocalTime(0, 0)),
+        )
+        assertThat(allDay.problems()).isEmpty()
+    }
+
+    @Test
+    fun `all-day end date before start date is a problem`() {
+        val bad = form(
+            isAllDay = true,
+            start = LocalDateTime(LocalDate(2026, 6, 11), LocalTime(0, 0)),
+            end = LocalDateTime(LocalDate(2026, 6, 10), LocalTime(0, 0)),
+        )
+        assertThat(bad.problems()).containsExactly(EventFormProblem.EndBeforeStart)
+    }
+
+    @Test
+    fun `problems accumulate`() {
+        val bad = form(
+            calendarId = null,
+            end = LocalDateTime(LocalDate(2026, 6, 11), LocalTime(9, 0)),
+        )
+        assertThat(bad.problems()).containsExactly(
+            EventFormProblem.NoCalendar,
+            EventFormProblem.EndBeforeStart,
+        )
+    }
+}

docs/superpowers/plans/2026-06-11-03-write-support.md

@@ -45,8 +45,8 @@ Domain bleibt pure Kotlin.
 
 | Slice | Inhalt | Status |
 |---|---|---|
-| v1.1 | Write-Fundament: `WRITE_CALENDAR`, `canModifyContents`, Delete (Serie + einzelnes Vorkommen) | in Arbeit |
+| v1.1 | Write-Fundament: `WRITE_CALENDAR`, `canModifyContents`, Delete (Serie + einzelnes Vorkommen) | ausgeliefert (v1.1.0, 2026-06-11) |
-| v1.2 | Create: Event-Formular (Titel, Kalender, ganztägig, Start/Ende, Ort, Beschreibung), FAB, Default-Kalender-Pref | offen |
+| v1.2 | Create: Event-Formular (Titel, Kalender, ganztägig, Start/Ende, Ort, Beschreibung), FAB, Default-Kalender-Pref | ausgeliefert (v1.2.0, 2026-06-11) |
 | v1.3 | Edit: Formular wiederverwendet, Serien-Edit, Reminder-Edit, einfacher Recurrence-Picker | offen |
 | v2.0 | Quick-Add, Occurrence-Edit, Konflikt-Dialog, Polish-Pass, Release | offen |
 
@@ -82,15 +82,18 @@ Domain bleibt pure Kotlin.
 - [x] `CalendarRepositoryImplTest`: delete-Pfade (Erfolg, Fehler)
 - [x] `CalendarMapperTest`: Access-Level-Mapping
 
-## v1.2 — Create (Skizze)
+## v1.2 — Create
 
-- `EventForm`-Domain-Modell + Validierung (Ende > Start, Titel-Fallback)
+- [x] `EventForm`-Domain-Modell + Validierung (`problems()`: EndBeforeStart,
-- `EventEditScreen` (ein Formular für Create+Edit), M3-Date/Time-Picker
+      NoCalendar; leerer Titel und Instant-Events erlaubt)
-- FAB auf allen drei Hauptansichten, vorbelegt mit sichtbarem Tag/Slot
+- [x] `EventEditScreen` (ein Formular, ab v1.3 auch für Edit), M3-Date/Time-Picker
-- `CalendarPrefs.defaultCalendarId` + Auswahl im Formular (nur beschreibbare
+- [x] FAB-Stack auf allen drei Hauptansichten (`CalendarFabColumn`: "+" immer,
-  Kalender anbieten)
+      Heute-Pill darüber), vorbelegt mit dem sichtbaren Tag
-- `insertEvent(form): Long` im DataSource (`DTSTART/DTEND/EVENT_TIMEZONE`,
+- [x] Kalender-Vorauswahl: explizit > zuletzt benutzt
-  all-day in UTC)
+      (`CalendarPrefs.lastUsedCalendarId` statt Settings-Eintrag) > erster
+      beschreibbarer; Picker bietet nur beschreibbare Kalender an
+- [x] `insertEvent(form): Long` im DataSource; `EventWriteMapper` (JVM-testbar)
+      normalisiert all-day auf UTC-Mitternächte mit exklusivem DTEND
 
 ## v1.3 — Edit (Skizze)