feat(detail): full-screen event detail (S4) with humanized recurrence

Tapping an event in the week/day timeline opens a full-screen detail
destination (MD3 list→detail, not a bottom sheet) overlaying the calendar
with a slide transition. One card per field (when, calendar, location,
description, attendees, recurrence) with leading icons; location taps open
a maps intent. Loading/Failure/Success throughout.

Recurrence is humanized from the RRULE — e.g. "Every week on Tue and Thu
until 31 Dec 2026" — covering FREQ/INTERVAL/BYDAY/UNTIL/COUNT with
abbreviated, italicised day names and localized list formatting, falling
back to a generic label for rules it can't render.

Also:
- fix: recurring events failed to open (series row stores DURATION, not
  DTEND, so the mapper dropped them as EventNotFound). The detail keeps
  them and shows the tapped occurrence's own times from Instances.
- feat: month day cell → opens the day view anchored to that date.
- build: add material-icons-extended (R8 strips unused icons in release).

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

.planning/ROADMAP.md

@@ -6,8 +6,8 @@
 |---|---|---|
 | v0.1 | Foundation & CI | complete |
 | v0.2 | Data Layer & Permission Flow | complete |
-| v0.3 | Month view | pending |
+| v0.3 | Month view | in progress |
-| v0.4 | Week view | pending |
+| v0.4 | Week view | in progress |
 | v0.5 | Day view | pending |
 | v0.6 | Event Detail Sheet | pending |
 | v0.7 | Filter & Settings | pending |

.planning/STATE.md

@@ -1,11 +1,12 @@
 # Calendula — Current State
 
-*Last updated: 2026-06-08*
+*Last updated: 2026-06-10*
 
 ## Status
 
-**Milestone:** v0.2 — Data Layer & Permission Flow
+**Milestone:** v0.4 — Week view (in progress)
-**Phase:** Plan 02 complete; UI-design iteration pending before Plan 03
+**Phase:** Month + Week views implemented; cross-cutting wiring (detail sheet,
+filter, settings, jump-to-date) still stubbed
 
 ## Progress
 
@@ -13,11 +14,15 @@
 - [x] V1 design decisions resolved (App name "Calendula", icon, seed color)
 - [x] Plan 01 written and executed — foundation lands (theme, icon, i18n, Hilt, DataStore, CI green)
 - [x] Plan 02 written and executed — data layer + permission flow + debug screen
-- [ ] UI-design iteration (mockups for Month/Week/Day/Detail/Filter/Settings, all three states)
+- [x] Month view (S1) — 6-week grid, event dots, today marker, swipe nav, three states (replaces debug screen)
-- [ ] Plan 03 (Month view)
+- [x] Week view (S2) — time schedule with overlap-resolved lanes, all-day strip, swipe nav, three states
+- [x] View-switcher (M1) wired — cycles Month ↔ Week (Day joins once S3 lands)
+- [ ] Day view (S3)
+- [ ] Event-detail sheet (S4) — week/month event taps are currently no-ops
+- [ ] Filter sheet (M3), Settings (M4), Jump-to-date (M2) — drawer entries stubbed
 
 ## Next
 
-1. Iterate on UI design (mockups per screen, all three states)
+1. Day view (S3) — slot it into the view-switcher cycle
-2. Write Plan 03: Month view
+2. Event-detail sheet (S4) — wire month-day and week-event taps to it
-3. Execute Plan 03 — Debug screen gets replaced by month view
+3. Revisit month/week UI polish + shared anchor-date continuity across views

CHANGELOG.md

@@ -7,6 +7,47 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [0.4.0] — 2026-06-10
+
+### Added
+- Event detail (S4): full-screen destination (MD3 list→detail, not a bottom
+  sheet) opened by tapping an event in the week/day timeline — title with a
+  calendar-colour accent line, a card per field (when, calendar, location,
+  description, attendees, recurrence) with leading icons, location tap opens a
+  maps intent, Loading/Failure/Success states, slide-in/out over the calendar
+- Human-readable recurrence: RRULE rendered as e.g. "Every week on _Tue_ and
+  _Thu_ until 31 Dec 2026" (FREQ/INTERVAL/BYDAY/UNTIL/COUNT, abbreviated +
+  italicised day names, localized list formatting), with a generic fallback
+- Month → day navigation: tapping a day cell opens the day view on that date
+
+### Fixed
+- Recurring events failed to open in the detail view: the series row stores
+  DURATION instead of DTEND, so the mapper dropped it (EventNotFound). The
+  detail now keeps such events and shows the tapped occurrence's own times
+  (from CalendarContract.Instances) instead of the series start
+
+## [0.3.0] — 2026-06-10
+
+### Added
+- Month view (S1): Material 3 Expressive card-per-day grid (only the current
+  month's weeks; neighbouring days left blank), per-day event dots with "+N"
+  overflow, today emphasised via `primaryContainer`, spring-based press
+  feedback from the active motion scheme, swipe + drawer navigation,
+  Loading/Failure/Success states
+- Week view (S2): vertical time schedule with overlap-resolved lanes,
+  separate all-day strip, midnight-spanning events clipped per day, swipe
+  navigation, Loading/Failure/Success states
+- Day view (S3): single-column slice of the week schedule reusing its
+  overlap-lane layout, per-day swipe navigation, noon-centred scroll that
+  persists across swipes, animated all-day strip, compact top bar with the
+  full date, Loading/Failure/Success states
+- Functional view-switcher (M1) cycling Month ↔ Week ↔ Day
+- Shared calendar UI building blocks in `ui/common/` (navigation drawer,
+  failure screen, view-switcher pill, color pastelizer, observable locale)
+
+### Removed
+- Throwaway debug screen — superseded by the month view
+
 ## [0.2.1] — 2026-06-09
 
 ### Changed

app/build.gradle.kts

@@ -98,6 +98,8 @@ dependencies {
     implementation(libs.androidx.ui.graphics)
     implementation(libs.androidx.ui.tooling.preview)
     implementation(libs.androidx.material3)
+    implementation(libs.androidx.compose.material.icons.core)
+    implementation(libs.androidx.compose.material.icons.extended)
 
     implementation(libs.hilt.android)
     implementation(libs.androidx.hilt.navigation.compose)

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

@@ -11,15 +11,25 @@ private const val TAG = "EventDetailMapper"
 
 internal fun ColumnReader.toEventDetailCore(attendees: List<Attendee>): EventDetail? {
     val begin = getLong(EventDetailProjection.IDX_DTSTART)
-    val end = getLong(EventDetailProjection.IDX_DTEND)
 
     if (begin < 0L) {
         Log.w(TAG, "Dropping event with negative dtstart=$begin")
         return null
     }
-    if (end < begin) {
+
-        Log.w(TAG, "Dropping event with dtend=$end < dtstart=$begin")
+    // Recurring events store DURATION instead of DTEND, so the series row's
-        return null
+    // DTEND is null. Keep the event (end == begin); callers that opened a
+    // specific occurrence supply the real per-occurrence times from
+    // CalendarContract.Instances. Only a present-but-backwards DTEND is malformed.
+    val end = if (isNull(EventDetailProjection.IDX_DTEND)) {
+        begin
+    } else {
+        val rawEnd = getLong(EventDetailProjection.IDX_DTEND)
+        if (rawEnd < begin) {
+            Log.w(TAG, "Dropping event with dtend=$rawEnd < dtstart=$begin")
+            return null
+        }
+        rawEnd
     }
 
     val rawTitle = getString(EventDetailProjection.IDX_TITLE)

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

@@ -0,0 +1,101 @@
+package de.jeanlucmakiola.calendula.ui
+
+import androidx.compose.animation.AnimatedVisibility
+import androidx.compose.animation.fadeIn
+import androidx.compose.animation.fadeOut
+import androidx.compose.animation.slideInHorizontally
+import androidx.compose.animation.slideOutHorizontally
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.runtime.Composable
+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.Modifier
+import de.jeanlucmakiola.calendula.domain.EventInstance
+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.month.MonthScreen
+import de.jeanlucmakiola.calendula.ui.week.WeekScreen
+import kotlinx.datetime.LocalDate
+
+/**
+ * Holds the active top-level view (spec M1) and swaps between the calendar
+ * screens. Each screen owns its own ViewModel and date anchor; the view-switcher
+ * pill in their top bars writes back here via [onSelectView].
+ */
+@Composable
+fun CalendarHost(modifier: Modifier = Modifier) {
+    var view by rememberSaveable { mutableStateOf(CalendarView.Month) }
+    val onSelectView: (CalendarView) -> Unit = { view = it }
+
+    // Tapping a day in the month grid opens the day view anchored to that date.
+    var pendingDayIso by rememberSaveable { mutableStateOf<String?>(null) }
+    val onOpenDay: (LocalDate) -> Unit = { date ->
+        pendingDayIso = date.toString()
+        view = CalendarView.Day
+    }
+
+    // The event-detail screen (S4) is a full-screen destination hoisted here so
+    // it overlays whichever calendar view is active. We forward the tapped
+    // occurrence's own times (eventId + begin + end, packed as a saveable
+    // long[]) so recurring events show the correct date, not the series start.
+    // [heldKey] keeps the last shown key alive through the slide-out (when
+    // [detailKey] is cleared); it is set in the tap callback — never a [0,0,0]
+    // placeholder — so the destination never loads a bogus id=0 on first frame.
+    var detailKey by rememberSaveable { mutableStateOf<LongArray?>(null) }
+    var heldKey by remember { mutableStateOf<LongArray?>(null) }
+    val onEventClick: (EventInstance) -> Unit = { event ->
+        val key = longArrayOf(
+            event.eventId,
+            event.start.toEpochMilliseconds(),
+            event.end.toEpochMilliseconds(),
+        )
+        heldKey = key
+        detailKey = key
+    }
+
+    val slideSpec = rememberCalendarSlideSpec()
+
+    Box(modifier = modifier.fillMaxSize()) {
+        when (view) {
+            CalendarView.Week -> WeekScreen(
+                selectedView = view,
+                onSelectView = onSelectView,
+                onEventClick = onEventClick,
+            )
+            CalendarView.Day -> DayScreen(
+                selectedView = view,
+                onSelectView = onSelectView,
+                onEventClick = onEventClick,
+                initialDateIso = pendingDayIso,
+            )
+            CalendarView.Month -> MonthScreen(
+                selectedView = view,
+                onSelectView = onSelectView,
+                onOpenDay = onOpenDay,
+            )
+        }
+
+        // Prefer the live key; fall back to the held one only while sliding out.
+        val activeKey = detailKey ?: heldKey
+        AnimatedVisibility(
+            visible = detailKey != null,
+            enter = slideInHorizontally(slideSpec) { it } + fadeIn(),
+            exit = slideOutHorizontally(slideSpec) { it } + fadeOut(),
+        ) {
+            activeKey?.let { key ->
+                EventDetailScreen(
+                    eventId = key[0],
+                    beginMillis = key[1],
+                    endMillis = key[2],
+                    onBack = { detailKey = null },
+                )
+            }
+        }
+    }
+}

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

@@ -2,21 +2,18 @@ package de.jeanlucmakiola.calendula.ui
 
 import android.Manifest
 import android.content.pm.PackageManager
-import androidx.compose.foundation.layout.padding
-import androidx.compose.material3.Scaffold
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.DisposableEffect
-import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.setValue
+import androidx.compose.runtime.getValue
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.platform.LocalContext
 import androidx.lifecycle.compose.LocalLifecycleOwner
 import androidx.core.content.ContextCompat
 import androidx.lifecycle.Lifecycle
 import androidx.lifecycle.LifecycleEventObserver
-import de.jeanlucmakiola.calendula.ui.debug.DebugScreen
 import de.jeanlucmakiola.calendula.ui.permission.PermissionScreen
 
 @Composable
@@ -42,14 +39,12 @@ fun RootScreen(modifier: Modifier = Modifier) {
         onDispose { lifecycle.removeObserver(obs) }
     }
 
-    Scaffold(modifier = modifier) { innerPadding ->
+    if (hasPermission) {
-        if (hasPermission) {
+        CalendarHost(modifier = modifier)
-            DebugScreen(modifier = Modifier.padding(innerPadding))
+    } else {
-        } else {
+        PermissionScreen(
-            PermissionScreen(
+            onGranted = { hasPermission = true },
-                onGranted = { hasPermission = true },
+            modifier = modifier,
-                modifier = Modifier.padding(innerPadding),
+        )
-            )
-        }
     }
 }

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

@@ -0,0 +1,17 @@
+package de.jeanlucmakiola.calendula.ui.common
+
+import androidx.compose.ui.graphics.Color
+
+/**
+ * Soften a raw calendar color toward a pastel that fits the active theme.
+ *  - Keeps the hue (so users still recognise their calendars)
+ *  - Caps saturation so harsh provider colors stop screaming
+ *  - Pins value/brightness to a band that reads on both light and dark surfaces
+ */
+fun pastelize(rawArgb: Int, dark: Boolean): Color {
+    val hsv = FloatArray(3)
+    android.graphics.Color.colorToHSV(rawArgb, hsv)
+    hsv[1] = (hsv[1] * 0.6f).coerceIn(0.25f, 0.65f)
+    hsv[2] = if (dark) 0.82f else 0.72f
+    return Color(android.graphics.Color.HSVToColor(hsv))
+}

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

@@ -0,0 +1,65 @@
+package de.jeanlucmakiola.calendula.ui.common
+
+import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.padding
+import androidx.compose.material3.HorizontalDivider
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.ModalDrawerSheet
+import androidx.compose.material3.NavigationDrawerItem
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.unit.dp
+import de.jeanlucmakiola.calendula.R
+
+/**
+ * Navigation drawer shared by every top-level calendar screen (M2/M3/M4
+ * entry points). Stateless — the host screen owns the drawer state and wires
+ * the callbacks.
+ */
+@Composable
+fun CalendarDrawer(
+    onToday: () -> Unit,
+    onJumpToDate: () -> Unit,
+    onFilter: () -> Unit,
+    onSettings: () -> Unit,
+) {
+    ModalDrawerSheet {
+        Text(
+            text = stringResource(R.string.app_name),
+            style = MaterialTheme.typography.titleLarge,
+            modifier = Modifier.padding(horizontal = 28.dp, vertical = 24.dp),
+        )
+        HorizontalDivider()
+        Spacer(Modifier.height(8.dp))
+        NavigationDrawerItem(
+            label = { Text(stringResource(R.string.month_today_action)) },
+            selected = false,
+            onClick = onToday,
+            modifier = Modifier.padding(horizontal = 12.dp),
+        )
+        NavigationDrawerItem(
+            label = { Text(stringResource(R.string.month_action_jump_to_date)) },
+            selected = false,
+            onClick = onJumpToDate,
+            modifier = Modifier.padding(horizontal = 12.dp),
+        )
+        NavigationDrawerItem(
+            label = { Text(stringResource(R.string.month_action_filter)) },
+            selected = false,
+            onClick = onFilter,
+            modifier = Modifier.padding(horizontal = 12.dp),
+        )
+        Spacer(Modifier.height(8.dp))
+        HorizontalDivider()
+        Spacer(Modifier.height(8.dp))
+        NavigationDrawerItem(
+            label = { Text(stringResource(R.string.month_action_settings)) },
+            selected = false,
+            onClick = onSettings,
+            modifier = Modifier.padding(horizontal = 12.dp),
+        )
+    }
+}

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

@@ -0,0 +1,56 @@
+package de.jeanlucmakiola.calendula.ui.common
+
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.padding
+import androidx.compose.material3.FilledTonalButton
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.text.style.TextAlign
+import androidx.compose.ui.unit.dp
+import de.jeanlucmakiola.calendula.R
+import de.jeanlucmakiola.calendula.domain.FailureReason
+
+/**
+ * Full-screen failure state shared by every calendar screen (spec §7).
+ * One explanation line + one recovery action, never a toast.
+ */
+@Composable
+fun CalendarFailure(reason: FailureReason, onRetry: () -> Unit) {
+    val titleRes = when (reason) {
+        FailureReason.PermissionRevoked -> R.string.state_failure_permission
+        FailureReason.NoCalendarsConfigured -> R.string.state_failure_no_calendars
+        FailureReason.ProviderUnavailable -> R.string.state_failure_provider
+        FailureReason.Unknown,
+        FailureReason.EventNotFound -> R.string.state_failure_unknown
+    }
+    val actionRes = when (reason) {
+        FailureReason.NoCalendarsConfigured -> R.string.state_failure_no_calendars_action
+        FailureReason.PermissionRevoked -> R.string.state_failure_permission_action
+        else -> R.string.state_retry
+    }
+    Column(
+        modifier = Modifier
+            .fillMaxSize()
+            .padding(32.dp),
+        verticalArrangement = Arrangement.Center,
+        horizontalAlignment = Alignment.CenterHorizontally,
+    ) {
+        Text(
+            text = stringResource(titleRes),
+            style = MaterialTheme.typography.headlineSmall,
+            textAlign = TextAlign.Center,
+        )
+        Spacer(Modifier.height(24.dp))
+        FilledTonalButton(onClick = onRetry) {
+            Text(stringResource(actionRes))
+        }
+    }
+}

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

@@ -0,0 +1,40 @@
+package de.jeanlucmakiola.calendula.ui.common
+
+import androidx.compose.animation.ContentTransform
+import androidx.compose.animation.core.FiniteAnimationSpec
+import androidx.compose.animation.slideInHorizontally
+import androidx.compose.animation.slideOutHorizontally
+import androidx.compose.animation.togetherWith
+import androidx.compose.material3.ExperimentalMaterial3ExpressiveApi
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.unit.IntOffset
+
+/**
+ * The M3 Expressive spatial spring used for the month/week slide: the *fast*
+ * spring-physics spec from the active motion scheme — snappy with a subtle
+ * springy settle, rather than a fixed easing curve.
+ *
+ * Read it in a composable scope (this helper) so it can be captured by the
+ * non-composable `AnimatedContent` transitionSpec lambda.
+ */
+@OptIn(ExperimentalMaterial3ExpressiveApi::class)
+@Composable
+fun rememberCalendarSlideSpec(): FiniteAnimationSpec<IntOffset> =
+    MaterialTheme.motionScheme.fastSpatialSpec()
+
+/**
+ * Horizontal slide for navigating between adjacent months/weeks.
+ *
+ * @param slideDir +1 = forward (incoming from the right), -1 = back, 0 = jump
+ *                 (e.g. "today"); a jump reuses the forward direction.
+ * @param spec     spatial animation spec, typically [rememberCalendarSlideSpec].
+ */
+fun calendarSlideTransition(
+    slideDir: Int,
+    spec: FiniteAnimationSpec<IntOffset>,
+): ContentTransform {
+    val dir = if (slideDir == 0) 1 else slideDir
+    return slideInHorizontally(spec) { w -> dir * w }
+        .togetherWith(slideOutHorizontally(spec) { w -> -dir * w })
+}

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

@@ -0,0 +1,25 @@
+package de.jeanlucmakiola.calendula.ui.common
+
+/**
+ * The top-level calendar views the user can switch between (spec M1).
+ * Day is declared but not yet implemented (v0.5) — see [IMPLEMENTED_VIEWS].
+ */
+enum class CalendarView {
+    Month,
+    Week,
+    Day,
+}
+
+/**
+ * Views that actually have a screen today. The view-switcher pill cycles
+ * through these in order.
+ */
+val IMPLEMENTED_VIEWS: List<CalendarView> =
+    listOf(CalendarView.Month, CalendarView.Week, CalendarView.Day)
+
+/** Next view in [available], wrapping around. Falls back to Month if absent. */
+fun CalendarView.next(available: List<CalendarView> = IMPLEMENTED_VIEWS): CalendarView {
+    val i = available.indexOf(this)
+    if (i < 0) return available.firstOrNull() ?: CalendarView.Month
+    return available[(i + 1) % available.size]
+}

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

@@ -0,0 +1,20 @@
+package de.jeanlucmakiola.calendula.ui.common
+
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.remember
+import androidx.compose.ui.platform.LocalConfiguration
+import androidx.core.os.ConfigurationCompat
+import java.util.Locale
+
+/**
+ * Current display [Locale], read observably from [LocalConfiguration] so the UI
+ * recomposes after a locale change (lint: NonObservableLocale). Used for
+ * weekday/month name formatting.
+ */
+@Composable
+fun currentLocale(): Locale {
+    val configuration = LocalConfiguration.current
+    return remember(configuration) {
+        ConfigurationCompat.getLocales(configuration).get(0) ?: Locale.getDefault()
+    }
+}

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

@@ -0,0 +1,33 @@
+package de.jeanlucmakiola.calendula.ui.common
+
+import androidx.compose.material3.FilledTonalButton
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.res.stringResource
+import de.jeanlucmakiola.calendula.R
+
+/**
+ * Top-bar pill that shows the current view and cycles to the next one on tap
+ * (spec M1: Month → Week → Day → Month, restricted to [IMPLEMENTED_VIEWS]).
+ */
+@Composable
+fun ViewSwitcherPill(
+    current: CalendarView,
+    onCycle: () -> Unit,
+    modifier: Modifier = Modifier,
+) {
+    val labelRes = when (current) {
+        CalendarView.Month -> R.string.view_month
+        CalendarView.Week -> R.string.view_week
+        CalendarView.Day -> R.string.view_day
+    }
+    FilledTonalButton(
+        onClick = onCycle,
+        shape = MaterialTheme.shapes.large,
+        modifier = modifier,
+    ) {
+        Text(stringResource(labelRes))
+    }
+}

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

@@ -0,0 +1,582 @@
+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
+import androidx.compose.foundation.isSystemInDarkTheme
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.BoxWithConstraints
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.fillMaxHeight
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.offset
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.width
+import androidx.compose.foundation.ScrollState
+import androidx.compose.foundation.rememberScrollState
+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
+import androidx.compose.material3.ModalNavigationDrawer
+import androidx.compose.material3.Scaffold
+import androidx.compose.material3.Text
+import androidx.compose.material3.TopAppBar
+import androidx.compose.material3.TopAppBarDefaults
+import androidx.compose.material3.rememberDrawerState
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.LaunchedEffect
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableFloatStateOf
+import androidx.compose.runtime.mutableIntStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.rememberCoroutineScope
+import androidx.compose.runtime.snapshotFlow
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.draw.clip
+import androidx.compose.ui.draw.clipToBounds
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.RectangleShape
+import androidx.compose.ui.input.nestedscroll.nestedScroll
+import androidx.compose.ui.input.pointer.pointerInput
+import androidx.compose.ui.platform.LocalDensity
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.semantics.contentDescription
+import androidx.compose.ui.semantics.semantics
+import androidx.compose.ui.text.style.TextOverflow
+import androidx.compose.ui.unit.Dp
+import androidx.compose.ui.unit.dp
+import androidx.hilt.navigation.compose.hiltViewModel
+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.CalendarFailure
+import de.jeanlucmakiola.calendula.ui.common.CalendarView
+import de.jeanlucmakiola.calendula.ui.common.ViewSwitcherPill
+import de.jeanlucmakiola.calendula.ui.common.calendarSlideTransition
+import de.jeanlucmakiola.calendula.ui.common.next
+import de.jeanlucmakiola.calendula.ui.common.pastelize
+import de.jeanlucmakiola.calendula.ui.common.rememberCalendarSlideSpec
+import de.jeanlucmakiola.calendula.ui.week.MINUTES_PER_DAY
+import de.jeanlucmakiola.calendula.ui.week.TimedBlock
+import kotlinx.coroutines.flow.first
+import kotlinx.coroutines.launch
+import kotlinx.datetime.LocalDate
+import java.time.format.TextStyle as JavaTextStyle
+import java.util.Locale
+import kotlin.math.roundToInt
+
+private val HOUR_HEIGHT = 56.dp
+private val GUTTER_WIDTH = 48.dp
+private val MIN_EVENT_HEIGHT = 24.dp
+private val ALL_DAY_ROW_HEIGHT = 24.dp
+private val ALL_DAY_VERTICAL_PADDING = 6.dp
+
+/** Total all-day strip height for the day (0 when there are no all-day events). */
+private fun DayUiState.Success.allDayStripHeight(): Dp {
+    if (allDay.isEmpty()) return 0.dp
+    val lanes = allDay.maxOf { it.lane } + 1
+    return ALL_DAY_ROW_HEIGHT * lanes + ALL_DAY_VERTICAL_PADDING * 2
+}
+
+@OptIn(ExperimentalMaterial3Api::class)
+@Composable
+fun DayScreen(
+    selectedView: CalendarView,
+    onSelectView: (CalendarView) -> Unit,
+    onEventClick: (EventInstance) -> Unit,
+    modifier: Modifier = Modifier,
+    initialDateIso: String? = null,
+    viewModel: DayViewModel = hiltViewModel(),
+) {
+    val state by viewModel.state.collectAsStateWithLifecycle()
+    val date by viewModel.date.collectAsStateWithLifecycle()
+
+    // When opened from the month grid, anchor to the tapped date.
+    LaunchedEffect(initialDateIso) {
+        initialDateIso?.let { viewModel.goToDate(LocalDate.parse(it)) }
+    }
+
+    val scrollBehavior = TopAppBarDefaults.pinnedScrollBehavior()
+    val drawerState = rememberDrawerState(DrawerValue.Closed)
+    val scope = rememberCoroutineScope()
+
+    // The all-day strip shares the app bar's scrolled colour so the whole top
+    // region elevates together once the timeline scrolls under it.
+    val topSectionColor by animateColorAsState(
+        targetValue = if (scrollBehavior.state.overlappedFraction > 0.01f) {
+            MaterialTheme.colorScheme.surfaceContainer
+        } else {
+            MaterialTheme.colorScheme.surface
+        },
+        label = "day-top-section-color",
+    )
+
+    val isOnToday = when (val s = state) {
+        is DayUiState.Success -> s.date == s.today
+        else -> true
+    }
+
+    // Slide direction for the day transition: +1 = next, -1 = prev, 0 = jump.
+    var slideDir by remember { mutableIntStateOf(0) }
+    val goNext = { slideDir = 1; viewModel.goToNext() }
+    val goPrev = { slideDir = -1; viewModel.goToPrev() }
+    val jumpToToday = { slideDir = 0; viewModel.goToToday() }
+
+    ModalNavigationDrawer(
+        drawerState = drawerState,
+        // Open only via the menu button — edge-swipe would fight the day swipe.
+        gesturesEnabled = drawerState.isOpen,
+        drawerContent = {
+            CalendarDrawer(
+                onToday = { jumpToToday(); scope.launch { drawerState.close() } },
+                onJumpToDate = { scope.launch { drawerState.close() } /* TODO: date picker */ },
+                onFilter = { scope.launch { drawerState.close() } /* TODO: filter sheet */ },
+                onSettings = { scope.launch { drawerState.close() } /* TODO: settings */ },
+            )
+        },
+    ) {
+        Scaffold(
+            modifier = modifier.nestedScroll(scrollBehavior.nestedScrollConnection),
+            topBar = {
+                DayTopBar(
+                    date = date,
+                    selectedView = selectedView,
+                    onCycleView = { onSelectView(selectedView.next()) },
+                    onOpenDrawer = { scope.launch { drawerState.open() } },
+                    scrollBehavior = scrollBehavior,
+                )
+            },
+            floatingActionButton = {
+                AnimatedVisibility(
+                    visible = !isOnToday,
+                    enter = scaleIn(),
+                    exit = scaleOut(),
+                ) {
+                    ExtendedFloatingActionButton(
+                        onClick = jumpToToday,
+                        icon = { Icon(Icons.Default.Refresh, contentDescription = null) },
+                        text = { Text(stringResource(R.string.day_today_action)) },
+                    )
+                }
+            },
+        ) { innerPadding ->
+            DayContent(
+                state = state,
+                slideDir = slideDir,
+                topSectionColor = topSectionColor,
+                onSwipeNext = goNext,
+                onSwipePrev = goPrev,
+                onRetry = jumpToToday,
+                onEventClick = onEventClick,
+                modifier = Modifier
+                    .padding(innerPadding)
+                    .fillMaxSize(),
+            )
+        }
+    }
+}
+
+@Composable
+private fun DayContent(
+    state: DayUiState,
+    slideDir: Int,
+    topSectionColor: Color,
+    onSwipeNext: () -> Unit,
+    onSwipePrev: () -> Unit,
+    onRetry: () -> Unit,
+    onEventClick: (EventInstance) -> Unit,
+    modifier: Modifier = Modifier,
+) {
+    val density = LocalDensity.current
+    val threshold = with(density) { 24.dp.toPx() }
+    var dragAccum by remember { mutableFloatStateOf(0f) }
+    val slideSpec = rememberCalendarSlideSpec()
+
+    // Hoisted above the per-day AnimatedContent so the vertical scroll position
+    // survives day-to-day swipes. We only centre on noon once, on first entry
+    // into the day view (i.e. when arriving from the month/week view).
+    val scrollState = rememberScrollState()
+    LaunchedEffect(Unit) {
+        snapshotFlow { scrollState.maxValue }.first { it > 0 }
+        val maxV = scrollState.maxValue
+        val target = with(density) {
+            (HOUR_HEIGHT.toPx() * 12 - (HOUR_HEIGHT.toPx() * 24 - maxV) / 2f).roundToInt()
+        }.coerceIn(0, maxV)
+        scrollState.scrollTo(target)
+    }
+
+    // Single, hoisted all-day strip height — shared by the outgoing and incoming
+    // day during a swipe, so the strip slides along but never jumps in height.
+    val targetAllDayHeight = (state as? DayUiState.Success)?.allDayStripHeight() ?: 0.dp
+    val allDayHeight by animateDpAsState(
+        targetValue = targetAllDayHeight,
+        label = "day-all-day-strip-height",
+    )
+
+    // Whole-page horizontal swipe, one level above the timeline's vertical
+    // scroll: a horizontal drag crosses this detector's slop, while a vertical
+    // drag is consumed by the inner scroll first — the two gestures coexist.
+    val swipeModifier = Modifier.pointerInput(Unit) {
+        detectHorizontalDragGestures(
+            onDragStart = { dragAccum = 0f },
+            onDragEnd = {
+                when {
+                    dragAccum < -threshold -> onSwipeNext()
+                    dragAccum > threshold -> onSwipePrev()
+                }
+                dragAccum = 0f
+            },
+            onDragCancel = { dragAccum = 0f },
+            onHorizontalDrag = { _, drag -> dragAccum += drag },
+        )
+    }
+
+    AnimatedContent(
+        targetState = state,
+        modifier = modifier.then(swipeModifier),
+        contentKey = { s ->
+            when (s) {
+                is DayUiState.Success -> "success-${s.date}"
+                is DayUiState.Failure -> "failure-${s.reason}"
+                DayUiState.Loading -> "loading"
+            }
+        },
+        transitionSpec = { calendarSlideTransition(slideDir, slideSpec) },
+        label = "day-transition",
+    ) { s ->
+        when (s) {
+            DayUiState.Loading -> DayLoading()
+            is DayUiState.Failure -> CalendarFailure(reason = s.reason, onRetry = onRetry)
+            is DayUiState.Success -> DaySuccess(
+                state = s,
+                topSectionColor = topSectionColor,
+                scrollState = scrollState,
+                allDayHeight = allDayHeight,
+                onEventClick = onEventClick,
+            )
+        }
+    }
+}
+
+@Composable
+private fun DaySuccess(
+    state: DayUiState.Success,
+    topSectionColor: Color,
+    scrollState: ScrollState,
+    allDayHeight: Dp,
+    onEventClick: (EventInstance) -> Unit,
+) {
+    Column(modifier = Modifier.fillMaxSize()) {
+        // All-day strip collapses to nothing when the day has no all-day events,
+        // so the timeline sits directly under the app bar.
+        AllDayStrip(
+            state = state,
+            height = allDayHeight,
+            onEventClick = onEventClick,
+            modifier = Modifier
+                .fillMaxWidth()
+                .background(topSectionColor),
+        )
+        // Breathing room between the (colour-shifting) top section and the
+        // scrolling timeline below.
+        Spacer(Modifier.height(8.dp))
+        Timeline(state = state, scrollState = scrollState, onEventClick = onEventClick)
+    }
+}
+
+@OptIn(ExperimentalMaterial3Api::class)
+@Composable
+private fun DayTopBar(
+    date: LocalDate,
+    selectedView: CalendarView,
+    onCycleView: () -> Unit,
+    onOpenDrawer: () -> Unit,
+    scrollBehavior: androidx.compose.material3.TopAppBarScrollBehavior,
+) {
+    TopAppBar(
+        title = {
+            Text(
+                text = formatDayTitle(date),
+                style = MaterialTheme.typography.titleLarge,
+            )
+        },
+        navigationIcon = {
+            IconButton(onClick = onOpenDrawer) {
+                Icon(
+                    imageVector = Icons.Default.Menu,
+                    contentDescription = stringResource(R.string.month_open_menu),
+                )
+            }
+        },
+        actions = {
+            ViewSwitcherPill(
+                current = selectedView,
+                onCycle = onCycleView,
+                modifier = Modifier.padding(end = 8.dp),
+            )
+        },
+        colors = TopAppBarDefaults.topAppBarColors(
+            containerColor = MaterialTheme.colorScheme.surface,
+            scrolledContainerColor = MaterialTheme.colorScheme.surfaceContainer,
+        ),
+        scrollBehavior = scrollBehavior,
+    )
+}
+
+@Composable
+private fun AllDayStrip(
+    state: DayUiState.Success,
+    height: Dp,
+    onEventClick: (EventInstance) -> Unit,
+    modifier: Modifier = Modifier,
+) {
+    val dark = isSystemInDarkTheme()
+
+    Row(
+        modifier = modifier
+            // Height is hoisted + animated so it resizes smoothly; padding sits
+            // inside it so the content area is lanes * row height.
+            .height(height)
+            .padding(vertical = ALL_DAY_VERTICAL_PADDING),
+    ) {
+        // Keep the gutter-width offset so the bars line up with the day column.
+        Spacer(Modifier.width(GUTTER_WIDTH))
+        // Bars are positioned absolutely by lane (vertical stacking); each spans
+        // the full day-column width. clipToBounds keeps bars from spilling out
+        // while the height animates.
+        BoxWithConstraints(
+            modifier = Modifier
+                .weight(1f)
+                .fillMaxHeight()
+                .clipToBounds(),
+        ) {
+            val barWidth = maxWidth
+            state.allDay.forEach { span ->
+                AllDayBar(
+                    event = span.event,
+                    dark = dark,
+                    onClick = { onEventClick(span.event) },
+                    modifier = Modifier
+                        .offset(y = ALL_DAY_ROW_HEIGHT * span.lane)
+                        .width(barWidth)
+                        .height(ALL_DAY_ROW_HEIGHT)
+                        .padding(horizontal = 1.dp, vertical = 1.dp),
+                )
+            }
+        }
+    }
+}
+
+@Composable
+private fun AllDayBar(
+    event: EventInstance,
+    dark: Boolean,
+    onClick: () -> Unit,
+    modifier: Modifier = Modifier,
+) {
+    val title = event.title.ifBlank { stringResource(R.string.event_untitled) }
+    Box(
+        modifier = modifier
+            .background(pastelize(event.color, dark), RoundedCornerShape(4.dp))
+            .clickable(onClick = onClick)
+            .padding(horizontal = 6.dp, vertical = 2.dp)
+            .semantics { contentDescription = title },
+        contentAlignment = Alignment.CenterStart,
+    ) {
+        Text(
+            text = title,
+            style = MaterialTheme.typography.labelSmall,
+            maxLines = 1,
+            overflow = TextOverflow.Ellipsis,
+            color = Color.Black.copy(alpha = 0.8f),
+        )
+    }
+}
+
+@Composable
+private fun Timeline(
+    state: DayUiState.Success,
+    scrollState: ScrollState,
+    onEventClick: (EventInstance) -> Unit,
+) {
+    val totalHeight = HOUR_HEIGHT * 24
+    val dark = isSystemInDarkTheme()
+
+    Box(modifier = Modifier.fillMaxSize()) {
+        // Gutter and day column are two scroll viewports that SHARE one scroll
+        // state, so they stay perfectly aligned. The day-column viewport is a
+        // static, rounded-clipped window — the content scrolls inside it, so the
+        // soft corners are permanent at any scroll position.
+        Row(modifier = Modifier.fillMaxSize()) {
+            // Hour gutter (scrolls in sync with the day column)
+            Column(
+                modifier = Modifier
+                    .width(GUTTER_WIDTH)
+                    .fillMaxHeight()
+                    .verticalScroll(scrollState),
+            ) {
+                (0 until 24).forEach { h ->
+                    Box(
+                        modifier = Modifier
+                            .fillMaxWidth()
+                            .height(HOUR_HEIGHT),
+                    ) {
+                        if (h > 0) {
+                            Text(
+                                text = "%02d".format(h),
+                                style = MaterialTheme.typography.labelSmall,
+                                color = MaterialTheme.colorScheme.onSurfaceVariant,
+                                modifier = Modifier
+                                    .align(Alignment.TopCenter)
+                                    .offset(y = (-6).dp),
+                            )
+                        }
+                    }
+                }
+            }
+            // Day column: rounded, clipped scroll viewport (permanent corners).
+            Box(
+                modifier = Modifier
+                    .weight(1f)
+                    .fillMaxHeight()
+                    .clip(RoundedCornerShape(16.dp))
+                    .verticalScroll(scrollState),
+            ) {
+                DayColumnCard(
+                    blocks = state.timed,
+                    dark = dark,
+                    onEventClick = onEventClick,
+                    modifier = Modifier
+                        .fillMaxWidth()
+                        .height(totalHeight),
+                )
+            }
+        }
+    }
+}
+
+@Composable
+private fun DayColumnCard(
+    blocks: List<TimedBlock>,
+    dark: Boolean,
+    onEventClick: (EventInstance) -> Unit,
+    modifier: Modifier = Modifier,
+) {
+    Card(
+        // Plain rectangular column — the soft corners come from the outer
+        // rounded scroll viewport, so inner rounding would look odd at the edges.
+        shape = RectangleShape,
+        colors = CardDefaults.cardColors(
+            containerColor = MaterialTheme.colorScheme.surfaceContainer,
+        ),
+        modifier = modifier,
+    ) {
+        BoxWithConstraints(modifier = Modifier.fillMaxSize()) {
+            val colWidth = maxWidth
+            blocks.forEach { block ->
+                val laneWidth = colWidth / block.laneCount
+                val top = HOUR_HEIGHT * (block.startMin / 60f)
+                val rawHeight = HOUR_HEIGHT * ((block.endMin - block.startMin) / 60f)
+                val height = if (rawHeight < MIN_EVENT_HEIGHT) MIN_EVENT_HEIGHT else rawHeight
+                EventBlock(
+                    block = block,
+                    dark = dark,
+                    onClick = { onEventClick(block.event) },
+                    modifier = Modifier
+                        .offset(x = laneWidth * block.lane, y = top)
+                        .width(laneWidth)
+                        .height(height)
+                        .padding(horizontal = 1.dp),
+                )
+            }
+        }
+    }
+}
+
+@Composable
+private fun EventBlock(
+    block: TimedBlock,
+    dark: Boolean,
+    onClick: () -> Unit,
+    modifier: Modifier = Modifier,
+) {
+    val title = block.event.title.ifBlank { stringResource(R.string.event_untitled) }
+    val timeLabel = "${minToHm(block.startMin)}–${minToHm(block.endMin)}"
+    val showTime = block.endMin - block.startMin >= 45
+    Box(
+        modifier = modifier
+            .background(pastelize(block.event.color, dark), RoundedCornerShape(4.dp))
+            .clickable(onClick = onClick)
+            .padding(horizontal = 4.dp, vertical = 2.dp)
+            .semantics { contentDescription = "$title, $timeLabel" },
+    ) {
+        Column {
+            Text(
+                text = title,
+                style = MaterialTheme.typography.labelMedium,
+                maxLines = if (showTime) 1 else 2,
+                overflow = TextOverflow.Ellipsis,
+                color = Color.Black.copy(alpha = 0.85f),
+            )
+            if (showTime) {
+                Text(
+                    text = timeLabel,
+                    style = MaterialTheme.typography.labelSmall,
+                    maxLines = 1,
+                    overflow = TextOverflow.Ellipsis,
+                    color = Color.Black.copy(alpha = 0.6f),
+                )
+            }
+        }
+    }
+}
+
+@Composable
+private fun DayLoading() {
+    val totalHeight = HOUR_HEIGHT * 24
+    val scrollState = rememberScrollState()
+    Row(modifier = Modifier.fillMaxSize().verticalScroll(scrollState)) {
+        Spacer(Modifier.width(GUTTER_WIDTH))
+        Box(
+            modifier = Modifier
+                .weight(1f)
+                .height(totalHeight)
+                .padding(horizontal = 2.dp)
+                .background(MaterialTheme.colorScheme.surfaceContainer),
+        )
+    }
+}
+
+private fun minToHm(min: Int): String =
+    if (min >= MINUTES_PER_DAY) "24:00" else "%02d:%02d".format(min / 60, min % 60)
+
+private fun formatDayTitle(date: LocalDate): String {
+    val locale = Locale.getDefault()
+    val java = java.time.LocalDate.of(date.year, date.month.ordinal + 1, date.day)
+    val weekday = java.dayOfWeek.getDisplayName(JavaTextStyle.SHORT, locale)
+    val monthName = java.month.getDisplayName(JavaTextStyle.SHORT, locale)
+    return "$weekday, ${date.day}. $monthName ${date.year}"
+}

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

@@ -0,0 +1,25 @@
+package de.jeanlucmakiola.calendula.ui.day
+
+import de.jeanlucmakiola.calendula.domain.FailureReason
+import de.jeanlucmakiola.calendula.ui.week.AllDaySpan
+import de.jeanlucmakiola.calendula.ui.week.TimedBlock
+import kotlinx.datetime.LocalDate
+
+/**
+ * The day view is a single-column slice of the week view (spec S3). It reuses the
+ * week's [TimedBlock] and [AllDaySpan] layout primitives — for one day, all-day
+ * spans collapse to a single column ([AllDaySpan.startCol] == [AllDaySpan.endCol]
+ * == 0) and only their [AllDaySpan.lane] (vertical stacking) matters.
+ */
+sealed interface DayUiState {
+    data object Loading : DayUiState
+    data class Failure(val reason: FailureReason) : DayUiState
+    data class Success(
+        val date: LocalDate,
+        val today: LocalDate,
+        /** All-day/multi-day events covering this day, stacked by lane. */
+        val allDay: List<AllDaySpan>,
+        /** Timed events clipped to this day with overlap lanes resolved. */
+        val timed: List<TimedBlock>,
+    ) : DayUiState
+}

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

@@ -0,0 +1,111 @@
+package de.jeanlucmakiola.calendula.ui.day
+
+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.domain.CalendarSource
+import de.jeanlucmakiola.calendula.domain.EventInstance
+import de.jeanlucmakiola.calendula.domain.FailureReason
+import de.jeanlucmakiola.calendula.ui.week.layoutAllDay
+import de.jeanlucmakiola.calendula.ui.week.layoutDay
+import kotlinx.coroutines.CoroutineDispatcher
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+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.flatMapLatest
+import kotlinx.coroutines.flow.flowOn
+import kotlinx.coroutines.flow.stateIn
+import kotlinx.datetime.DateTimeUnit
+import kotlinx.datetime.LocalDate
+import kotlinx.datetime.TimeZone
+import kotlinx.datetime.atStartOfDayIn
+import kotlinx.datetime.atTime
+import kotlinx.datetime.minus
+import kotlinx.datetime.plus
+import kotlinx.datetime.toInstant
+import kotlinx.datetime.toLocalDateTime
+import kotlin.time.Clock
+import kotlin.time.Instant
+import javax.inject.Inject
+
+@OptIn(ExperimentalCoroutinesApi::class)
+@HiltViewModel
+class DayViewModel @Inject constructor(
+    private val repository: CalendarRepository,
+    @IoDispatcher private val io: CoroutineDispatcher,
+) : ViewModel() {
+
+    private val zone = TimeZone.currentSystemDefault()
+
+    private val todayDate: LocalDate
+        get() = Clock.System.now().toLocalDateTime(zone).date
+
+    private val _date = MutableStateFlow(todayDate)
+    val date: StateFlow<LocalDate> = _date
+
+    val state: StateFlow<DayUiState> = _date
+        .flatMapLatest { day ->
+            val range = dayRange(day, zone)
+            combine(
+                repository.calendars(),
+                repository.instances(range),
+            ) { calendars, instances ->
+                buildState(day, calendars, instances)
+            }
+        }
+        .catch { emit(DayUiState.Failure(FailureReason.ProviderUnavailable)) }
+        .flowOn(io)
+        .stateIn(
+            scope = viewModelScope,
+            started = SharingStarted.WhileSubscribed(5_000L),
+            initialValue = DayUiState.Loading,
+        )
+
+    fun goToPrev() {
+        _date.value = _date.value.minus(1, DateTimeUnit.DAY)
+    }
+
+    fun goToNext() {
+        _date.value = _date.value.plus(1, DateTimeUnit.DAY)
+    }
+
+    fun goToToday() {
+        _date.value = todayDate
+    }
+
+    /** Jump to a specific date (e.g. when opened from the month grid). */
+    fun goToDate(date: LocalDate) {
+        _date.value = date
+    }
+
+    private fun buildState(
+        day: LocalDate,
+        calendars: List<CalendarSource>,
+        instances: List<EventInstance>,
+    ): DayUiState {
+        if (calendars.isEmpty()) {
+            return DayUiState.Failure(FailureReason.NoCalendarsConfigured)
+        }
+        val days = listOf(day)
+        val allDay = instances.filter { it.isAllDay }
+        val timed = instances.filterNot { it.isAllDay }
+        return DayUiState.Success(
+            date = day,
+            today = todayDate,
+            allDay = layoutAllDay(allDay, days, zone),
+            timed = layoutDay(timed, day, zone),
+        )
+    }
+}
+
+/** Half-open instant range covering the single calendar [date]. */
+internal fun dayRange(date: LocalDate, zone: TimeZone): ClosedRange<Instant> {
+    val from = date.atStartOfDayIn(zone)
+    val to = date.atTime(23, 59, 59).toInstant(zone)
+    return from..to
+}

app/src/main/java/de/jeanlucmakiola/calendula/ui/debug/DebugScreen.kt

@@ -1,164 +0,0 @@
-package de.jeanlucmakiola.calendula.ui.debug
-
-import androidx.compose.foundation.background
-import androidx.compose.foundation.layout.Arrangement
-import androidx.compose.foundation.layout.Box
-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.lazy.LazyColumn
-import androidx.compose.foundation.lazy.items
-import androidx.compose.foundation.shape.CircleShape
-import androidx.compose.material3.CircularProgressIndicator
-import androidx.compose.material3.HorizontalDivider
-import androidx.compose.material3.MaterialTheme
-import androidx.compose.material3.Text
-import androidx.compose.runtime.Composable
-import androidx.compose.runtime.getValue
-import androidx.compose.ui.Alignment
-import androidx.compose.ui.Modifier
-import androidx.compose.ui.graphics.Color
-import androidx.compose.ui.res.stringResource
-import androidx.compose.ui.unit.dp
-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.EventInstance
-import kotlinx.datetime.TimeZone
-import kotlinx.datetime.toLocalDateTime
-
-@Composable
-fun DebugScreen(
-    modifier: Modifier = Modifier,
-    viewModel: DebugViewModel = hiltViewModel(),
-) {
-    val state by viewModel.state.collectAsStateWithLifecycle()
-    Column(modifier = modifier.fillMaxSize()) {
-        DebugBanner()
-        when (val s = state) {
-            DebugUiState.Loading -> LoadingContent()
-            is DebugUiState.Failure -> FailureContent()
-            is DebugUiState.Success -> SuccessContent(s)
-        }
-    }
-}
-
-@Composable
-private fun DebugBanner() {
-    Box(
-        modifier = Modifier
-            .fillMaxWidth()
-            .background(MaterialTheme.colorScheme.tertiaryContainer)
-            .padding(horizontal = 16.dp, vertical = 8.dp),
-    ) {
-        Text(
-            text = stringResource(R.string.debug_banner),
-            style = MaterialTheme.typography.labelMedium,
-            color = MaterialTheme.colorScheme.onTertiaryContainer,
-        )
-    }
-}
-
-@Composable
-private fun LoadingContent() {
-    Box(modifier = Modifier.fillMaxSize(), contentAlignment = Alignment.Center) {
-        CircularProgressIndicator()
-    }
-}
-
-@Composable
-private fun FailureContent() {
-    Box(modifier = Modifier.fillMaxSize().padding(24.dp), contentAlignment = Alignment.Center) {
-        Text(
-            text = stringResource(R.string.state_failure_provider),
-            style = MaterialTheme.typography.bodyLarge,
-        )
-    }
-}
-
-@Composable
-private fun SuccessContent(state: DebugUiState.Success) {
-    LazyColumn(
-        modifier = Modifier.fillMaxSize().padding(horizontal = 16.dp),
-        verticalArrangement = Arrangement.spacedBy(4.dp),
-    ) {
-        item { SectionHeader(stringResource(R.string.debug_calendars_header)) }
-        if (state.calendars.isEmpty()) {
-            item {
-                Text(
-                    text = stringResource(R.string.debug_no_calendars),
-                    style = MaterialTheme.typography.bodyMedium,
-                )
-            }
-        } else {
-            items(state.calendars, key = { "cal-${it.id}" }) { CalendarRow(it) }
-        }
-
-        item { Spacer(Modifier.height(16.dp)) }
-        item { SectionHeader(stringResource(R.string.debug_events_header)) }
-
-        if (state.nextEvents.isEmpty()) {
-            item {
-                Text(
-                    text = stringResource(R.string.debug_no_events),
-                    style = MaterialTheme.typography.bodyMedium,
-                )
-            }
-        } else {
-            items(
-                state.nextEvents,
-                // Recurring events share Instances._ID across occurrences, so
-                // include the start instant to keep the LazyColumn key unique.
-                key = { "evt-${it.instanceId}-${it.start.toEpochMilliseconds()}" },
-            ) { EventRow(it) }
-        }
-    }
-}
-
-@Composable
-private fun SectionHeader(text: String) {
-    Column(modifier = Modifier.padding(vertical = 8.dp)) {
-        Text(text = text, style = MaterialTheme.typography.titleMedium)
-        HorizontalDivider()
-    }
-}
-
-@Composable
-private fun CalendarRow(cal: CalendarSource) {
-    Row(
-        modifier = Modifier.fillMaxWidth().padding(vertical = 6.dp),
-        verticalAlignment = Alignment.CenterVertically,
-    ) {
-        Box(
-            modifier = Modifier
-                .size(12.dp)
-                .background(Color(cal.color), CircleShape),
-        )
-        Text(
-            text = "  ${cal.displayName}  (${cal.accountName})",
-            style = MaterialTheme.typography.bodyMedium,
-        )
-    }
-}
-
-@Composable
-private fun EventRow(event: EventInstance) {
-    val zone = TimeZone.currentSystemDefault()
-    val start = event.start.toLocalDateTime(zone)
-    Column(modifier = Modifier.fillMaxWidth().padding(vertical = 4.dp)) {
-        Text(text = event.title, style = MaterialTheme.typography.bodyMedium)
-        val date = "%04d-%02d-%02d".format(start.year, start.month.ordinal + 1, start.day)
-        val time = "%02d:%02d".format(start.hour, start.minute)
-        Text(
-            text = "$date  $time",
-            style = MaterialTheme.typography.bodySmall,
-            color = MaterialTheme.colorScheme.onSurfaceVariant,
-        )
-    }
-}

app/src/main/java/de/jeanlucmakiola/calendula/ui/debug/DebugUiState.kt

@@ -1,14 +0,0 @@
-package de.jeanlucmakiola.calendula.ui.debug
-
-import de.jeanlucmakiola.calendula.domain.CalendarSource
-import de.jeanlucmakiola.calendula.domain.EventInstance
-import de.jeanlucmakiola.calendula.domain.FailureReason
-
-sealed interface DebugUiState {
-    data object Loading : DebugUiState
-    data class Failure(val reason: FailureReason) : DebugUiState
-    data class Success(
-        val calendars: List<CalendarSource>,
-        val nextEvents: List<EventInstance>,
-    ) : DebugUiState
-}

app/src/main/java/de/jeanlucmakiola/calendula/ui/debug/DebugViewModel.kt

@@ -1,49 +0,0 @@
-package de.jeanlucmakiola.calendula.ui.debug
-
-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.domain.FailureReason
-import kotlinx.coroutines.CoroutineDispatcher
-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.stateIn
-import kotlin.time.Duration.Companion.days
-import kotlin.time.Instant
-import javax.inject.Inject
-
-private const val MAX_DEBUG_EVENTS = 50
-private val DEBUG_WINDOW = 30.days
-
-@HiltViewModel
-class DebugViewModel @Inject constructor(
-    private val repository: CalendarRepository,
-    @IoDispatcher private val io: CoroutineDispatcher,
-) : ViewModel() {
-
-    val state: StateFlow<DebugUiState> = run {
-        val now = Instant.fromEpochMilliseconds(System.currentTimeMillis())
-        val range = now..(now + DEBUG_WINDOW)
-        combine(
-            repository.calendars(),
-            repository.instances(range),
-        ) { calendars, instances ->
-            DebugUiState.Success(
-                calendars = calendars,
-                nextEvents = instances.take(MAX_DEBUG_EVENTS),
-            ) as DebugUiState
-        }
-            .catch { emit(DebugUiState.Failure(FailureReason.ProviderUnavailable)) }
-            .flowOn(io)
-            .stateIn(
-                scope = viewModelScope,
-                started = SharingStarted.WhileSubscribed(5_000L),
-                initialValue = DebugUiState.Loading,
-            )
-    }
-}

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

@@ -0,0 +1,536 @@
+package de.jeanlucmakiola.calendula.ui.detail
+
+import android.content.ActivityNotFoundException
+import android.content.Context
+import android.content.Intent
+import android.icu.text.ListFormatter
+import android.net.Uri
+import androidx.activity.compose.BackHandler
+import androidx.compose.foundation.background
+import androidx.compose.foundation.clickable
+import androidx.compose.foundation.isSystemInDarkTheme
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.ColumnScope
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.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.shape.RoundedCornerShape
+import androidx.compose.foundation.verticalScroll
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.automirrored.filled.ArrowBack
+import androidx.compose.material.icons.automirrored.filled.Notes
+import androidx.compose.material.icons.filled.CalendarMonth
+import androidx.compose.material.icons.filled.Delete
+import androidx.compose.material.icons.filled.Edit
+import androidx.compose.material.icons.filled.People
+import androidx.compose.material.icons.filled.Place
+import androidx.compose.material.icons.filled.Repeat
+import androidx.compose.material.icons.filled.Schedule
+import androidx.compose.material3.ExperimentalMaterial3Api
+import androidx.compose.material3.Icon
+import androidx.compose.material3.IconButton
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Scaffold
+import androidx.compose.material3.Surface
+import androidx.compose.material3.Text
+import androidx.compose.material3.TopAppBar
+import androidx.compose.material3.TopAppBarDefaults
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.LaunchedEffect
+import androidx.compose.runtime.getValue
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.vector.ImageVector
+import androidx.compose.ui.platform.LocalContext
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.text.AnnotatedString
+import androidx.compose.ui.text.SpanStyle
+import androidx.compose.ui.text.buildAnnotatedString
+import androidx.compose.ui.text.font.FontStyle
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.unit.Dp
+import androidx.compose.ui.unit.dp
+import androidx.hilt.navigation.compose.hiltViewModel
+import androidx.lifecycle.compose.collectAsStateWithLifecycle
+import de.jeanlucmakiola.calendula.R
+import de.jeanlucmakiola.calendula.domain.Attendee
+import de.jeanlucmakiola.calendula.domain.AttendeeStatus
+import de.jeanlucmakiola.calendula.domain.EventInstance
+import de.jeanlucmakiola.calendula.ui.common.CalendarFailure
+import de.jeanlucmakiola.calendula.ui.common.pastelize
+import kotlinx.datetime.TimeZone
+import java.time.DayOfWeek
+import java.time.ZoneId
+import java.time.format.DateTimeFormatter
+import java.time.format.FormatStyle
+import java.time.format.TextStyle as JavaTextStyle
+import java.util.Locale
+import kotlin.time.Duration.Companion.seconds
+import kotlin.time.Instant
+
+/**
+ * Read-only full-screen event detail (spec S4, realised as a navigation
+ * destination rather than a bottom sheet — MD3 list→detail pattern). Back
+ * gesture and the top-bar arrow both return to the calendar. The only action is
+ * tapping the location to open a maps intent.
+ */
+@OptIn(ExperimentalMaterial3Api::class)
+@Composable
+fun EventDetailScreen(
+    eventId: Long,
+    beginMillis: Long,
+    endMillis: Long,
+    onBack: () -> Unit,
+    viewModel: EventDetailViewModel = hiltViewModel(),
+) {
+    LaunchedEffect(eventId, beginMillis, endMillis) {
+        viewModel.open(eventId, beginMillis, endMillis)
+    }
+    val state by viewModel.state.collectAsStateWithLifecycle()
+
+    BackHandler(onBack = onBack)
+
+    Scaffold(
+        topBar = {
+            TopAppBar(
+                title = {},
+                navigationIcon = {
+                    IconButton(onClick = onBack) {
+                        Icon(
+                            imageVector = Icons.AutoMirrored.Filled.ArrowBack,
+                            contentDescription = stringResource(R.string.event_detail_back),
+                        )
+                    }
+                },
+                actions = {
+                    IconButton(onClick = { /* TODO: edit event (V2) */ }) {
+                        Icon(
+                            imageVector = Icons.Default.Edit,
+                            contentDescription = stringResource(R.string.event_detail_edit),
+                        )
+                    }
+                    IconButton(onClick = { /* TODO: delete event (V2) */ }) {
+                        Icon(
+                            imageVector = Icons.Default.Delete,
+                            contentDescription = stringResource(R.string.event_detail_delete),
+                        )
+                    }
+                },
+                colors = TopAppBarDefaults.topAppBarColors(
+                    containerColor = MaterialTheme.colorScheme.surface,
+                ),
+            )
+        },
+    ) { innerPadding ->
+        val contentModifier = Modifier
+            .fillMaxSize()
+            .padding(innerPadding)
+        when (val s = state) {
+            EventDetailUiState.Loading -> EventDetailLoading(contentModifier)
+            is EventDetailUiState.Failure -> CalendarFailure(
+                reason = s.reason,
+                onRetry = viewModel::retry,
+            )
+            is EventDetailUiState.Success -> EventDetailContent(s, contentModifier)
+        }
+    }
+}
+
+@Composable
+private fun EventDetailContent(state: EventDetailUiState.Success, modifier: Modifier = Modifier) {
+    val detail = state.detail
+    val instance = detail.instance
+    val dark = isSystemInDarkTheme()
+    val locale = currentDetailLocale()
+    val accent = pastelize(instance.color, dark)
+
+    Column(
+        modifier = modifier
+            .verticalScroll(rememberScrollState())
+            .padding(start = 24.dp, end = 24.dp, top = 8.dp, bottom = 40.dp),
+    ) {
+        // Title with a short accent line in the calendar colour underneath.
+        Text(
+            text = instance.title.ifBlank { stringResource(R.string.event_untitled) },
+            style = MaterialTheme.typography.headlineMedium,
+            fontWeight = FontWeight.SemiBold,
+        )
+        Spacer(Modifier.height(10.dp))
+        Box(
+            modifier = Modifier
+                .width(48.dp)
+                .height(3.dp)
+                .background(accent, RoundedCornerShape(2.dp)),
+        )
+
+        Spacer(Modifier.height(20.dp))
+
+        // Every piece of info shares one card design: a tonal container with a
+        // leading icon in the gutter and the value to the right. 12dp gaps stack
+        // them cleanly.
+        val gap = 12.dp
+
+        // "When" — date/all-day plus the time range.
+        val (whenPrimary, whenSecondary) = formatWhen(instance, TimeZone.currentSystemDefault(), locale)
+        DetailCard(icon = Icons.Default.Schedule, iconContentDescription = null) {
+            Text(text = whenPrimary, style = MaterialTheme.typography.titleMedium)
+            if (whenSecondary != null) {
+                Spacer(Modifier.height(2.dp))
+                Text(
+                    text = whenSecondary,
+                    style = MaterialTheme.typography.bodyMedium,
+                    color = MaterialTheme.colorScheme.onSurfaceVariant,
+                )
+            }
+        }
+
+        // Calendar — icon tinted in the calendar colour conveys identity, so no
+        // separate colour dot is needed.
+        Spacer(Modifier.height(gap))
+        DetailCard(
+            icon = Icons.Default.CalendarMonth,
+            iconTint = accent,
+            iconContentDescription = stringResource(R.string.event_detail_calendar),
+        ) {
+            Text(
+                text = state.calendarName ?: stringResource(R.string.event_detail_calendar_unknown),
+                style = MaterialTheme.typography.titleMedium,
+            )
+        }
+
+        // Location (conditional, tap → maps).
+        instance.location?.takeIf { it.isNotBlank() }?.let { location ->
+            val context = LocalContext.current
+            Spacer(Modifier.height(gap))
+            DetailCard(
+                icon = Icons.Default.Place,
+                iconContentDescription = stringResource(R.string.event_detail_location),
+            ) {
+                Text(
+                    text = location,
+                    style = MaterialTheme.typography.titleMedium,
+                    color = MaterialTheme.colorScheme.primary,
+                    modifier = Modifier
+                        .fillMaxWidth()
+                        .clickable { openInMaps(context, location) }
+                        .padding(vertical = 2.dp),
+                )
+            }
+        }
+
+        // Description (conditional).
+        detail.description?.takeIf { it.isNotBlank() }?.let { description ->
+            Spacer(Modifier.height(gap))
+            DetailCard(
+                icon = Icons.AutoMirrored.Filled.Notes,
+                iconContentDescription = stringResource(R.string.event_detail_description),
+            ) {
+                Text(text = description, style = MaterialTheme.typography.bodyMedium)
+            }
+        }
+
+        // Attendees (conditional).
+        detail.attendees.takeIf { it.isNotEmpty() }?.let { attendees ->
+            Spacer(Modifier.height(gap))
+            DetailCard(
+                icon = Icons.Default.People,
+                iconContentDescription = stringResource(R.string.event_detail_attendees),
+            ) {
+                attendees.forEach { AttendeeRow(it) }
+            }
+        }
+
+        // Recurrence (conditional) — humanised from the RRULE.
+        detail.rrule?.takeIf { it.isNotBlank() }?.let { rrule ->
+            Spacer(Modifier.height(gap))
+            DetailCard(
+                icon = Icons.Default.Repeat,
+                iconContentDescription = stringResource(R.string.event_detail_recurrence),
+            ) {
+                Text(
+                    text = recurrenceText(rrule, locale),
+                    style = MaterialTheme.typography.titleMedium,
+                )
+            }
+        }
+    }
+}
+
+/** One info card: tonal container, leading icon in the gutter, value to the right. */
+@Composable
+private fun DetailCard(
+    icon: ImageVector,
+    iconContentDescription: String?,
+    iconTint: Color = MaterialTheme.colorScheme.onSurfaceVariant,
+    content: @Composable ColumnScope.() -> Unit,
+) {
+    Surface(
+        color = MaterialTheme.colorScheme.surfaceContainerHigh,
+        shape = RoundedCornerShape(16.dp),
+        modifier = Modifier.fillMaxWidth(),
+    ) {
+        Row(
+            modifier = Modifier.padding(16.dp),
+            verticalAlignment = Alignment.CenterVertically,
+        ) {
+            Icon(
+                imageVector = icon,
+                contentDescription = iconContentDescription,
+                tint = iconTint,
+                modifier = Modifier.size(24.dp),
+            )
+            Spacer(Modifier.width(16.dp))
+            Column(modifier = Modifier.weight(1f), content = content)
+        }
+    }
+}
+
+@Composable
+private fun AttendeeRow(attendee: Attendee) {
+    Row(
+        modifier = Modifier
+            .fillMaxWidth()
+            .padding(vertical = 3.dp),
+        horizontalArrangement = Arrangement.SpaceBetween,
+        verticalAlignment = Alignment.CenterVertically,
+    ) {
+        Text(
+            text = attendee.name.ifBlank { attendee.email.orEmpty() },
+            style = MaterialTheme.typography.bodyMedium,
+        )
+        Text(
+            text = stringResource(attendeeStatusLabel(attendee.status)),
+            style = MaterialTheme.typography.labelSmall,
+            color = MaterialTheme.colorScheme.onSurfaceVariant,
+        )
+    }
+}
+
+@Composable
+private fun EventDetailLoading(modifier: Modifier = Modifier) {
+    Column(modifier = modifier.padding(start = 24.dp, end = 24.dp, top = 16.dp)) {
+        SkeletonBar(widthFraction = 0.7f, height = 32.dp)
+        Spacer(Modifier.height(24.dp))
+        SkeletonBar(widthFraction = 1f, height = 64.dp)
+        Spacer(Modifier.height(28.dp))
+        SkeletonBar(widthFraction = 0.35f, height = 14.dp)
+        Spacer(Modifier.height(8.dp))
+        SkeletonBar(widthFraction = 0.6f, height = 16.dp)
+        Spacer(Modifier.height(24.dp))
+        SkeletonBar(widthFraction = 0.35f, height = 14.dp)
+        Spacer(Modifier.height(8.dp))
+        SkeletonBar(widthFraction = 0.8f, height = 16.dp)
+    }
+}
+
+@Composable
+private fun SkeletonBar(widthFraction: Float, height: Dp) {
+    Box(
+        modifier = Modifier
+            .fillMaxWidth(widthFraction)
+            .height(height)
+            .background(
+                MaterialTheme.colorScheme.surfaceContainerHighest,
+                RoundedCornerShape(8.dp),
+            ),
+    )
+}
+
+// --- helpers -------------------------------------------------------------
+
+@Composable
+private fun currentDetailLocale(): Locale {
+    val config = LocalContext.current.resources.configuration
+    return config.locales[0] ?: Locale.getDefault()
+}
+
+private fun attendeeStatusLabel(status: AttendeeStatus): Int = when (status) {
+    AttendeeStatus.Accepted -> R.string.event_attendee_accepted
+    AttendeeStatus.Declined -> R.string.event_attendee_declined
+    AttendeeStatus.Tentative -> R.string.event_attendee_tentative
+    AttendeeStatus.NeedsAction -> R.string.event_attendee_needs_action
+    AttendeeStatus.Unknown -> R.string.event_attendee_unknown
+}
+
+/**
+ * Humanise an RFC 5545 RRULE into a localized phrase, e.g.
+ * "Every week on Tue and Thu until 31 Dec 2026" or "Every day, 10 times".
+ * Falls back to a generic label for rules we don't render in full (ordinal
+ * monthly/yearly BYDAY, etc.).
+ */
+@Composable
+private fun recurrenceText(rrule: String, locale: Locale): AnnotatedString {
+    val parts = rrule.removePrefix("RRULE:").split(';').mapNotNull { token ->
+        val eq = token.indexOf('=')
+        if (eq <= 0) null else token.substring(0, eq).uppercase() to token.substring(eq + 1)
+    }.toMap()
+
+    val freq = parts["FREQ"]?.uppercase()
+    val interval = parts["INTERVAL"]?.toIntOrNull() ?: 1
+    val base = when (freq) {
+        "DAILY" -> if (interval == 1) stringResource(R.string.recurrence_daily)
+        else stringResource(R.string.recurrence_every_n_days, interval)
+        "WEEKLY" -> if (interval == 1) stringResource(R.string.recurrence_weekly)
+        else stringResource(R.string.recurrence_every_n_weeks, interval)
+        "MONTHLY" -> if (interval == 1) stringResource(R.string.recurrence_monthly)
+        else stringResource(R.string.recurrence_every_n_months, interval)
+        "YEARLY" -> if (interval == 1) stringResource(R.string.recurrence_yearly)
+        else stringResource(R.string.recurrence_every_n_years, interval)
+        else -> return AnnotatedString(stringResource(R.string.event_detail_recurring))
+    }
+
+    // Weekly + BYDAY → "<base> on <days>"; other BYDAY forms keep just the base.
+    // The day names + their joined block are tracked so only the names (not the
+    // commas/conjunction) can be italicised in the final string.
+    val byDay = parts["BYDAY"]
+    var dayNames: List<String>? = null
+    var joinedDays: String? = null
+    val main = if (freq == "WEEKLY" && !byDay.isNullOrBlank()) {
+        val days = byDay.split(',').mapNotNull { rruleDayName(it.trim(), locale) }
+        if (days.isNotEmpty()) {
+            val joined = ListFormatter.getInstance(locale).format(days)
+            dayNames = days
+            joinedDays = joined
+            stringResource(R.string.recurrence_on_days, base, joined)
+        } else {
+            base
+        }
+    } else {
+        base
+    }
+
+    // End bound: UNTIL (a date) takes precedence over COUNT (a number of times).
+    val until = parts["UNTIL"]?.let { parseUntilDate(it, locale) }
+    val count = parts["COUNT"]?.toIntOrNull()
+    val full = when {
+        until != null -> stringResource(R.string.recurrence_with_until, main, until)
+        count != null -> stringResource(R.string.recurrence_with_count, main, count)
+        else -> main
+    }
+
+    return buildAnnotatedString {
+        append(full)
+        val names = dayNames
+        val joined = joinedDays
+        if (names != null && joined != null) {
+            // Italicise each day name within the joined block only — leaving the
+            // separators and conjunction ("und"/"and") in the regular style.
+            val regionStart = full.indexOf(joined)
+            if (regionStart >= 0) {
+                val regionEnd = regionStart + joined.length
+                var cursor = regionStart
+                for (name in names) {
+                    val at = full.indexOf(name, cursor)
+                    if (at in regionStart until regionEnd) {
+                        addStyle(SpanStyle(fontStyle = FontStyle.Italic), at, at + name.length)
+                        cursor = at + name.length
+                    }
+                }
+            }
+        }
+    }
+}
+
+/** Map an RRULE BYDAY token (e.g. "TU" or "2TH") to a localized short weekday name. */
+private fun rruleDayName(token: String, locale: Locale): String? {
+    val dow = when (token.takeLast(2).uppercase()) {
+        "MO" -> DayOfWeek.MONDAY
+        "TU" -> DayOfWeek.TUESDAY
+        "WE" -> DayOfWeek.WEDNESDAY
+        "TH" -> DayOfWeek.THURSDAY
+        "FR" -> DayOfWeek.FRIDAY
+        "SA" -> DayOfWeek.SATURDAY
+        "SU" -> DayOfWeek.SUNDAY
+        else -> return null
+    }
+    return dow.getDisplayName(JavaTextStyle.SHORT, locale)
+}
+
+/** Parse an RRULE UNTIL value ("20261231" or "20261231T235959Z") to a localized date. */
+private fun parseUntilDate(raw: String, locale: Locale): String? {
+    val digits = raw.takeWhile { it.isDigit() }
+    if (digits.length < 8) return null
+    return try {
+        val date = java.time.LocalDate.of(
+            digits.substring(0, 4).toInt(),
+            digits.substring(4, 6).toInt(),
+            digits.substring(6, 8).toInt(),
+        )
+        DateTimeFormatter.ofLocalizedDate(FormatStyle.MEDIUM).withLocale(locale).format(date)
+    } catch (e: Exception) {
+        null
+    }
+}
+
+/**
+ * Format an event's time into a primary line (date, or "All day") and an
+ * optional secondary line (time range). Multi-day timed events collapse into a
+ * single primary line spanning both ends.
+ */
+@Composable
+private fun formatWhen(
+    instance: EventInstance,
+    zone: TimeZone,
+    locale: Locale,
+): Pair<String, String?> {
+    val zid = ZoneId.of(zone.id)
+    val dateFull = DateTimeFormatter.ofLocalizedDate(FormatStyle.FULL).withLocale(locale)
+    val dateMedium = DateTimeFormatter.ofLocalizedDate(FormatStyle.MEDIUM).withLocale(locale)
+    val timeShort = DateTimeFormatter.ofLocalizedTime(FormatStyle.SHORT).withLocale(locale)
+
+    val startLdt = instance.start.toJavaLocalDateTime(zid)
+    val allDayLabel = stringResource(R.string.event_detail_all_day)
+
+    if (instance.isAllDay) {
+        // All-day end is the exclusive next midnight; step back to the last
+        // covered day so a one-day event reads as a single date.
+        val lastLdt = (instance.end - 1.seconds).toJavaLocalDateTime(zid)
+        return if (startLdt.toLocalDate() == lastLdt.toLocalDate()) {
+            allDayLabel to dateFull.format(startLdt.toLocalDate())
+        } else {
+            allDayLabel to
+                "${dateMedium.format(startLdt.toLocalDate())} – ${dateMedium.format(lastLdt.toLocalDate())}"
+        }
+    }
+
+    val endLdt = instance.end.toJavaLocalDateTime(zid)
+    return if (startLdt.toLocalDate() == endLdt.toLocalDate()) {
+        dateFull.format(startLdt.toLocalDate()) to
+            "${timeShort.format(startLdt)} – ${timeShort.format(endLdt)}"
+    } else {
+        val start = "${dateMedium.format(startLdt.toLocalDate())} ${timeShort.format(startLdt)}"
+        val end = "${dateMedium.format(endLdt.toLocalDate())} ${timeShort.format(endLdt)}"
+        "$start – $end" to null
+    }
+}
+
+private fun Instant.toJavaLocalDateTime(zid: ZoneId): java.time.LocalDateTime =
+    java.time.LocalDateTime.ofInstant(java.time.Instant.ofEpochMilli(toEpochMilliseconds()), zid)
+
+/** Open a maps intent for [query]; fall back to a web maps URL if no app handles geo:. */
+private fun openInMaps(context: Context, query: String) {
+    val encoded = Uri.encode(query)
+    val geo = Intent(Intent.ACTION_VIEW, Uri.parse("geo:0,0?q=$encoded"))
+    try {
+        context.startActivity(geo)
+    } catch (e: ActivityNotFoundException) {
+        val web = Intent(
+            Intent.ACTION_VIEW,
+            Uri.parse("https://www.google.com/maps/search/?api=1&query=$encoded"),
+        )
+        try {
+            context.startActivity(web)
+        } catch (e2: ActivityNotFoundException) {
+            // No browser either — nothing sensible to do; swallow.
+        }
+    }
+}

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

@@ -0,0 +1,17 @@
+package de.jeanlucmakiola.calendula.ui.detail
+
+import de.jeanlucmakiola.calendula.domain.EventDetail
+import de.jeanlucmakiola.calendula.domain.FailureReason
+
+/**
+ * UI state for the event-detail bottom sheet (spec S4). Read-only in V1.
+ */
+sealed interface EventDetailUiState {
+    data object Loading : EventDetailUiState
+    data class Failure(val reason: FailureReason) : EventDetailUiState
+    data class Success(
+        val detail: EventDetail,
+        /** Display name of the owning calendar, null if it can't be resolved. */
+        val calendarName: String?,
+    ) : EventDetailUiState
+}

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

@@ -0,0 +1,101 @@
+package de.jeanlucmakiola.calendula.ui.detail
+
+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.calendar.NoSuchEventException
+import de.jeanlucmakiola.calendula.data.di.IoDispatcher
+import de.jeanlucmakiola.calendula.domain.FailureReason
+import kotlinx.coroutines.CoroutineDispatcher
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.SharingStarted
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.combine
+import kotlinx.coroutines.flow.first
+import kotlinx.coroutines.flow.flatMapLatest
+import kotlinx.coroutines.flow.flow
+import kotlinx.coroutines.flow.flowOf
+import kotlinx.coroutines.flow.flowOn
+import kotlinx.coroutines.flow.stateIn
+import kotlin.coroutines.cancellation.CancellationException
+import kotlin.time.Instant
+import javax.inject.Inject
+
+/**
+ * Loads a single event's detail on demand for the bottom sheet (spec S4).
+ * The event id is set via [open]; the sheet observes [state].
+ */
+@OptIn(ExperimentalCoroutinesApi::class)
+@HiltViewModel
+class EventDetailViewModel @Inject constructor(
+    private val repository: CalendarRepository,
+    @IoDispatcher private val io: CoroutineDispatcher,
+) : ViewModel() {
+
+    private val _target = MutableStateFlow<Target?>(null)
+    // Bumped by retry() to re-run the load for the same target.
+    private val _reload = MutableStateFlow(0)
+
+    val state: StateFlow<EventDetailUiState> =
+        combine(_target, _reload) { target, _ -> target }
+            .flatMapLatest { target ->
+                if (target == null) {
+                    flowOf<EventDetailUiState>(EventDetailUiState.Loading)
+                } else {
+                    flow {
+                        emit(EventDetailUiState.Loading)
+                        emit(loadDetail(target))
+                    }
+                }
+            }
+            .flowOn(io)
+            .stateIn(
+                scope = viewModelScope,
+                started = SharingStarted.WhileSubscribed(5_000L),
+                initialValue = EventDetailUiState.Loading,
+            )
+
+    /**
+     * Open (or switch) to the tapped occurrence. [beginMillis]/[endMillis] are
+     * the occurrence's own times (from `CalendarContract.Instances`); they
+     * override the series DTSTART/DTEND so recurring events show the correct
+     * date instead of the first occurrence.
+     */
+    fun open(eventId: Long, beginMillis: Long, endMillis: Long) {
+        _target.value = Target(eventId, beginMillis, endMillis)
+    }
+
+    /** Re-run the current load after a failure. */
+    fun retry() {
+        _reload.value += 1
+    }
+
+    private suspend fun loadDetail(target: Target): EventDetailUiState = try {
+        val detail = repository.eventDetail(target.eventId)
+        // The Events row holds the series start; replace it with this
+        // occurrence's time so recurring events render correctly.
+        val corrected = detail.copy(
+            instance = detail.instance.copy(
+                start = Instant.fromEpochMilliseconds(target.beginMillis),
+                end = Instant.fromEpochMilliseconds(target.endMillis),
+            ),
+        )
+        val calendarName = repository.calendars().first()
+            .firstOrNull { it.id == corrected.instance.calendarId }
+            ?.displayName
+        EventDetailUiState.Success(corrected, calendarName)
+    } catch (e: CancellationException) {
+        throw e
+    } catch (e: NoSuchEventException) {
+        EventDetailUiState.Failure(FailureReason.EventNotFound)
+    } catch (e: SecurityException) {
+        EventDetailUiState.Failure(FailureReason.PermissionRevoked)
+    } catch (e: Exception) {
+        EventDetailUiState.Failure(FailureReason.ProviderUnavailable)
+    }
+
+    /** A tapped occurrence: the series [eventId] plus this occurrence's own times. */
+    private data class Target(val eventId: Long, val beginMillis: Long, val endMillis: Long)
+}

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

@@ -0,0 +1,474 @@
+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
+import androidx.compose.foundation.interaction.collectIsPressedAsState
+import androidx.compose.foundation.isSystemInDarkTheme
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Box
+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.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
+import androidx.compose.material3.ModalNavigationDrawer
+import androidx.compose.material3.Scaffold
+import androidx.compose.material3.Text
+import androidx.compose.material3.TopAppBar
+import androidx.compose.material3.TopAppBarDefaults
+import androidx.compose.material3.rememberDrawerState
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableFloatStateOf
+import androidx.compose.runtime.mutableIntStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.rememberCoroutineScope
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.graphics.graphicsLayer
+import androidx.compose.ui.input.nestedscroll.nestedScroll
+import androidx.compose.ui.input.pointer.pointerInput
+import androidx.compose.ui.platform.LocalDensity
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.semantics.contentDescription
+import androidx.compose.ui.semantics.semantics
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.text.style.TextAlign
+import androidx.compose.ui.unit.dp
+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.CalendarFailure
+import de.jeanlucmakiola.calendula.ui.common.CalendarView
+import de.jeanlucmakiola.calendula.ui.common.ViewSwitcherPill
+import de.jeanlucmakiola.calendula.ui.common.calendarSlideTransition
+import de.jeanlucmakiola.calendula.ui.common.currentLocale
+import de.jeanlucmakiola.calendula.ui.common.rememberCalendarSlideSpec
+import de.jeanlucmakiola.calendula.ui.common.next
+import de.jeanlucmakiola.calendula.ui.common.pastelize
+import kotlinx.coroutines.launch
+import kotlinx.datetime.DateTimeUnit
+import kotlinx.datetime.DayOfWeek
+import kotlinx.datetime.LocalDate
+import kotlinx.datetime.YearMonth
+import kotlinx.datetime.plus
+import java.time.format.TextStyle as JavaTextStyle
+import java.util.Locale
+
+@OptIn(ExperimentalMaterial3Api::class)
+@Composable
+fun MonthScreen(
+    selectedView: CalendarView,
+    onSelectView: (CalendarView) -> Unit,
+    onOpenDay: (LocalDate) -> Unit,
+    modifier: Modifier = Modifier,
+    viewModel: MonthViewModel = hiltViewModel(),
+) {
+    val state by viewModel.state.collectAsStateWithLifecycle()
+    val month by viewModel.month.collectAsStateWithLifecycle()
+
+    val scrollBehavior = TopAppBarDefaults.pinnedScrollBehavior()
+    val drawerState = rememberDrawerState(DrawerValue.Closed)
+    val scope = rememberCoroutineScope()
+
+    val isOnCurrentMonth = when (val s = state) {
+        is MonthUiState.Success -> s.month == YearMonth(s.today.year, s.today.month)
+        else -> true
+    }
+
+    // Slide direction for the grid transition: +1 = next, -1 = prev, 0 = jump (no slide).
+    var slideDir by remember { mutableIntStateOf(0) }
+
+    val goNext = {
+        slideDir = 1
+        viewModel.goToNext()
+    }
+    val goPrev = {
+        slideDir = -1
+        viewModel.goToPrev()
+    }
+    val jumpToToday = {
+        slideDir = 0
+        viewModel.goToToday()
+    }
+
+    ModalNavigationDrawer(
+        drawerState = drawerState,
+        // Open only via the menu button — edge-swipe would fight the month swipe.
+        gesturesEnabled = drawerState.isOpen,
+        drawerContent = {
+            CalendarDrawer(
+                onToday = {
+                    jumpToToday()
+                    scope.launch { drawerState.close() }
+                },
+                onJumpToDate = { scope.launch { drawerState.close() } /* TODO: open date picker */ },
+                onFilter = { scope.launch { drawerState.close() } /* TODO: open filter sheet */ },
+                onSettings = { scope.launch { drawerState.close() } /* TODO: navigate to settings */ },
+            )
+        },
+    ) {
+        Scaffold(
+            modifier = modifier.nestedScroll(scrollBehavior.nestedScrollConnection),
+            topBar = {
+                MonthTopBar(
+                    month = month,
+                    selectedView = selectedView,
+                    onCycleView = { onSelectView(selectedView.next()) },
+                    onOpenDrawer = { scope.launch { drawerState.open() } },
+                    scrollBehavior = scrollBehavior,
+                )
+            },
+            floatingActionButton = {
+                AnimatedVisibility(
+                    visible = !isOnCurrentMonth,
+                    enter = scaleIn(),
+                    exit = scaleOut(),
+                ) {
+                    ExtendedFloatingActionButton(
+                        onClick = jumpToToday,
+                        icon = { Icon(Icons.Default.Refresh, contentDescription = null) },
+                        text = { Text(stringResource(R.string.month_today_action)) },
+                    )
+                }
+            },
+        ) { innerPadding ->
+            Column(
+                modifier = Modifier
+                    .padding(innerPadding)
+                    .fillMaxSize(),
+            ) {
+                WeekdayHeader(weekStart = DayOfWeek.MONDAY)
+                MonthContent(
+                    state = state,
+                    slideDir = slideDir,
+                    onSwipeNext = goNext,
+                    onSwipePrev = goPrev,
+                    onRetry = jumpToToday,
+                    onOpenDay = onOpenDay,
+                )
+            }
+        }
+    }
+}
+
+@Composable
+private fun MonthContent(
+    state: MonthUiState,
+    slideDir: Int,
+    onSwipeNext: () -> Unit,
+    onSwipePrev: () -> Unit,
+    onRetry: () -> Unit,
+    onOpenDay: (LocalDate) -> Unit,
+) {
+    val density = LocalDensity.current
+    val threshold = with(density) { 6.dp.toPx() }
+    var dragAccum by remember { mutableFloatStateOf(0f) }
+    val slideSpec = rememberCalendarSlideSpec()
+
+    val swipeModifier = Modifier.pointerInput(Unit) {
+        detectHorizontalDragGestures(
+            onDragStart = { dragAccum = 0f },
+            onDragEnd = {
+                when {
+                    dragAccum < -threshold -> onSwipeNext()
+                    dragAccum > threshold -> onSwipePrev()
+                }
+                dragAccum = 0f
+            },
+            onDragCancel = { dragAccum = 0f },
+            onHorizontalDrag = { _, drag -> dragAccum += drag },
+        )
+    }
+
+    AnimatedContent(
+        targetState = state,
+        modifier = Modifier.fillMaxSize().then(swipeModifier),
+        contentKey = { s ->
+            when (s) {
+                is MonthUiState.Success -> "success-${s.month}"
+                is MonthUiState.Failure -> "failure-${s.reason}"
+                MonthUiState.Loading -> "loading"
+            }
+        },
+        transitionSpec = { calendarSlideTransition(slideDir, slideSpec) },
+        label = "month-transition",
+    ) { s ->
+        when (s) {
+            MonthUiState.Loading -> MonthGridLoading()
+            is MonthUiState.Failure -> CalendarFailure(reason = s.reason, onRetry = onRetry)
+            is MonthUiState.Success -> MonthGrid(
+                state = s,
+                weekStart = DayOfWeek.MONDAY,
+                onOpenDay = onOpenDay,
+            )
+        }
+    }
+}
+
+@OptIn(ExperimentalMaterial3Api::class)
+@Composable
+private fun MonthTopBar(
+    month: YearMonth,
+    selectedView: CalendarView,
+    onCycleView: () -> Unit,
+    onOpenDrawer: () -> Unit,
+    scrollBehavior: androidx.compose.material3.TopAppBarScrollBehavior,
+) {
+    TopAppBar(
+        title = {
+            Text(
+                text = formatMonthYear(month),
+                style = MaterialTheme.typography.titleLarge,
+            )
+        },
+        navigationIcon = {
+            IconButton(onClick = onOpenDrawer) {
+                Icon(
+                    imageVector = Icons.Default.Menu,
+                    contentDescription = stringResource(R.string.month_open_menu),
+                )
+            }
+        },
+        actions = {
+            ViewSwitcherPill(
+                current = selectedView,
+                onCycle = onCycleView,
+                modifier = Modifier.padding(end = 8.dp),
+            )
+        },
+        scrollBehavior = scrollBehavior,
+    )
+}
+
+@Composable
+private fun WeekdayHeader(weekStart: DayOfWeek) {
+    val locale = currentLocale()
+    val days = remember(weekStart, locale) {
+        (0 until 7).map { offset ->
+            DayOfWeek.entries[((weekStart.ordinal + offset) % 7)]
+        }
+    }
+    Row(
+        modifier = Modifier
+            .fillMaxWidth()
+            .padding(horizontal = 8.dp, vertical = 4.dp),
+    ) {
+        days.forEach { dow ->
+            val isWeekend = dow == DayOfWeek.SATURDAY || dow == DayOfWeek.SUNDAY
+            val javaDow = java.time.DayOfWeek.of(dow.ordinal + 1)
+            Text(
+                text = javaDow.getDisplayName(JavaTextStyle.SHORT, locale),
+                style = MaterialTheme.typography.labelMedium,
+                color = if (isWeekend) MaterialTheme.colorScheme.onSurfaceVariant
+                        else MaterialTheme.colorScheme.onSurface,
+                textAlign = TextAlign.Center,
+                modifier = Modifier.weight(1f),
+            )
+        }
+    }
+}
+
+@Composable
+private fun MonthGrid(
+    state: MonthUiState.Success,
+    weekStart: DayOfWeek,
+    onOpenDay: (LocalDate) -> Unit,
+) {
+    val firstOfMonth = LocalDate(state.month.year, state.month.month, 1)
+    val gridStart = firstOfMonth.startOfGridWeek(weekStart)
+
+    // Show only the weeks the current month actually touches; leading/trailing
+    // days of neighbouring months are left blank rather than rendered.
+    val leadOffset = ((firstOfMonth.dayOfWeek.ordinal - weekStart.ordinal) + 7) % 7
+    val daysInMonth =
+        java.time.YearMonth.of(state.month.year, state.month.month.ordinal + 1).lengthOfMonth()
+    val weeks = (leadOffset + daysInMonth + 6) / 7
+
+    Column(
+        modifier = Modifier
+            .fillMaxSize()
+            .padding(horizontal = 8.dp, vertical = 4.dp),
+        verticalArrangement = Arrangement.spacedBy(8.dp),
+    ) {
+        repeat(weeks) { row ->
+            Row(
+                modifier = Modifier
+                    .fillMaxWidth()
+                    .weight(1f),
+                horizontalArrangement = Arrangement.spacedBy(4.dp),
+            ) {
+                repeat(7) { col ->
+                    val date = gridStart.plus(row * 7 + col, DateTimeUnit.DAY)
+                    val inMonth =
+                        date.month == state.month.month && date.year == state.month.year
+                    if (inMonth) {
+                        DayCard(
+                            date = date,
+                            isToday = date == state.today,
+                            data = state.cells[date],
+                            onClick = { onOpenDay(date) },
+                            modifier = Modifier.weight(1f),
+                        )
+                    } else {
+                        Spacer(Modifier.weight(1f))
+                    }
+                }
+            }
+        }
+    }
+}
+
+@OptIn(ExperimentalMaterial3ExpressiveApi::class)
+@Composable
+private fun DayCard(
+    date: LocalDate,
+    isToday: Boolean,
+    data: DayCellData?,
+    onClick: () -> Unit,
+    modifier: Modifier = Modifier,
+) {
+    val todayPrefix = stringResource(R.string.month_a11y_today_prefix)
+    val cellLabel = buildString {
+        if (isToday) append(todayPrefix).append(", ")
+        append(date.year).append('-')
+        append((date.month.ordinal + 1).toString().padStart(2, '0')).append('-')
+        append(date.day.toString().padStart(2, '0'))
+        data?.let { append(", ").append(it.count).append(" Events") }
+    }
+
+    // M3 Expressive press feedback: a spatial spring from the active motion
+    // scheme drives a subtle scale, instead of a fixed easing curve.
+    val interactionSource = remember { MutableInteractionSource() }
+    val pressed by interactionSource.collectIsPressedAsState()
+    val scale by animateFloatAsState(
+        targetValue = if (pressed) 0.94f else 1f,
+        animationSpec = MaterialTheme.motionScheme.fastSpatialSpec(),
+        label = "day-card-press",
+    )
+
+    Card(
+        onClick = onClick,
+        interactionSource = interactionSource,
+        shape = MaterialTheme.shapes.medium,
+        colors = CardDefaults.cardColors(
+            containerColor = if (isToday) MaterialTheme.colorScheme.primaryContainer
+            else MaterialTheme.colorScheme.surfaceContainerHigh,
+            contentColor = if (isToday) MaterialTheme.colorScheme.onPrimaryContainer
+            else MaterialTheme.colorScheme.onSurface,
+        ),
+        modifier = modifier
+            .fillMaxSize()
+            .graphicsLayer {
+                scaleX = scale
+                scaleY = scale
+            }
+            .semantics { contentDescription = cellLabel },
+    ) {
+        Column(
+            modifier = Modifier
+                .fillMaxSize()
+                .padding(top = 4.dp, bottom = 2.dp),
+            horizontalAlignment = Alignment.CenterHorizontally,
+        ) {
+            Text(
+                text = date.day.toString(),
+                style = MaterialTheme.typography.labelLarge,
+                fontWeight = if (isToday) FontWeight.Bold else FontWeight.Normal,
+            )
+            Spacer(Modifier.height(2.dp))
+            EventDotRow(data)
+        }
+    }
+}
+
+@Composable
+private fun EventDotRow(data: DayCellData?) {
+    if (data == null || data.swatches.isEmpty()) {
+        Spacer(Modifier.height(6.dp))
+        return
+    }
+    val dark = isSystemInDarkTheme()
+    Row(
+        horizontalArrangement = Arrangement.spacedBy(2.dp),
+        verticalAlignment = Alignment.CenterVertically,
+    ) {
+        data.swatches.forEach { argb ->
+            Box(
+                modifier = Modifier
+                    .size(6.dp)
+                    .background(pastelize(argb, dark), CircleShape),
+            )
+        }
+        if (data.count > data.swatches.size) {
+            Text(
+                text = "+${data.count - data.swatches.size}",
+                style = MaterialTheme.typography.labelSmall,
+                color = MaterialTheme.colorScheme.onSurfaceVariant,
+            )
+        }
+    }
+}
+
+@Composable
+private fun MonthGridLoading() {
+    val shape = MaterialTheme.shapes.medium
+    Column(
+        modifier = Modifier
+            .fillMaxSize()
+            .padding(horizontal = 8.dp, vertical = 4.dp),
+        verticalArrangement = Arrangement.spacedBy(4.dp),
+    ) {
+        repeat(6) {
+            Row(
+                modifier = Modifier
+                    .fillMaxWidth()
+                    .weight(1f),
+                horizontalArrangement = Arrangement.spacedBy(4.dp),
+            ) {
+                repeat(7) {
+                    Box(
+                        modifier = Modifier
+                            .weight(1f)
+                            .fillMaxSize()
+                            .background(
+                                color = MaterialTheme.colorScheme.surfaceContainerHigh,
+                                shape = shape,
+                            ),
+                    )
+                }
+            }
+        }
+    }
+}
+
+private fun formatMonthYear(ym: YearMonth): String {
+    val locale = Locale.getDefault()
+    val name = java.time.Month.of(ym.month.ordinal + 1)
+        .getDisplayName(JavaTextStyle.FULL, locale)
+    return "$name ${ym.year}"
+}

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

@@ -0,0 +1,28 @@
+package de.jeanlucmakiola.calendula.ui.month
+
+import de.jeanlucmakiola.calendula.domain.FailureReason
+import kotlinx.datetime.LocalDate
+import kotlinx.datetime.YearMonth
+
+/**
+ * Per-day aggregation surfaced to the month grid. We only need
+ *   - the total event count (drives the optional "+N" indicator), and
+ *   - up to three calendar colors for the dot row.
+ *
+ * The day cell never holds full event objects — the detail sheet pulls those
+ * lazily.
+ */
+data class DayCellData(
+    val count: Int,
+    val swatches: List<Int>,
+)
+
+sealed interface MonthUiState {
+    data object Loading : MonthUiState
+    data class Failure(val reason: FailureReason) : MonthUiState
+    data class Success(
+        val month: YearMonth,
+        val today: LocalDate,
+        val cells: Map<LocalDate, DayCellData>,
+    ) : MonthUiState
+}

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

@@ -0,0 +1,128 @@
+package de.jeanlucmakiola.calendula.ui.month
+
+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.domain.CalendarSource
+import de.jeanlucmakiola.calendula.domain.EventInstance
+import de.jeanlucmakiola.calendula.domain.FailureReason
+import kotlinx.coroutines.CoroutineDispatcher
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+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.flatMapLatest
+import kotlinx.coroutines.flow.flowOn
+import kotlinx.coroutines.flow.stateIn
+import kotlinx.datetime.DateTimeUnit
+import kotlinx.datetime.DayOfWeek
+import kotlinx.datetime.LocalDate
+import kotlinx.datetime.TimeZone
+import kotlinx.datetime.YearMonth
+import kotlinx.datetime.atStartOfDayIn
+import kotlinx.datetime.atTime
+import kotlinx.datetime.minus
+import kotlinx.datetime.plus
+import kotlinx.datetime.toInstant
+import kotlinx.datetime.toLocalDateTime
+import kotlin.time.Clock
+import kotlin.time.Instant
+import javax.inject.Inject
+
+@OptIn(ExperimentalCoroutinesApi::class)
+@HiltViewModel
+class MonthViewModel @Inject constructor(
+    private val repository: CalendarRepository,
+    @IoDispatcher private val io: CoroutineDispatcher,
+) : ViewModel() {
+
+    private val zone = TimeZone.currentSystemDefault()
+
+    // V1: week starts Monday. DataStore-driven preference comes with Settings.
+    private val weekStart: DayOfWeek = DayOfWeek.MONDAY
+
+    private val todayDate: LocalDate
+        get() = Clock.System.now().toLocalDateTime(zone).date
+
+    private val _month = MutableStateFlow(YearMonth(todayDate.year, todayDate.month))
+    val month: StateFlow<YearMonth> = _month
+
+    val state: StateFlow<MonthUiState> = _month
+        .flatMapLatest { ym ->
+            val range = monthGridRange(ym, weekStart, zone)
+            combine(
+                repository.calendars(),
+                repository.instances(range),
+            ) { calendars, instances ->
+                buildState(ym, calendars, instances)
+            }
+        }
+        .catch { emit(MonthUiState.Failure(FailureReason.ProviderUnavailable)) }
+        .flowOn(io)
+        .stateIn(
+            scope = viewModelScope,
+            started = SharingStarted.WhileSubscribed(5_000L),
+            initialValue = MonthUiState.Loading,
+        )
+
+    fun goToPrev() {
+        _month.value = _month.value.minus(1, DateTimeUnit.MONTH)
+    }
+
+    fun goToNext() {
+        _month.value = _month.value.plus(1, DateTimeUnit.MONTH)
+    }
+
+    fun goToToday() {
+        _month.value = YearMonth(todayDate.year, todayDate.month)
+    }
+
+    private fun buildState(
+        ym: YearMonth,
+        calendars: List<CalendarSource>,
+        instances: List<EventInstance>,
+    ): MonthUiState {
+        if (calendars.isEmpty()) {
+            return MonthUiState.Failure(FailureReason.NoCalendarsConfigured)
+        }
+        val byDay = instances.groupBy { it.start.toLocalDateTime(zone).date }
+            .mapValues { (_, evs) ->
+                DayCellData(
+                    count = evs.size,
+                    swatches = evs.map { it.color }.distinct().take(3),
+                )
+            }
+        return MonthUiState.Success(
+            month = ym,
+            today = todayDate,
+            cells = byDay,
+        )
+    }
+}
+
+/**
+ * The on-screen grid spans 6 weeks anchored on [weekStart]. Includes the
+ * trailing days of the previous month and the leading days of the next month.
+ */
+internal fun monthGridRange(
+    ym: YearMonth,
+    weekStart: DayOfWeek,
+    zone: TimeZone,
+): ClosedRange<Instant> {
+    val firstOfMonth = LocalDate(ym.year, ym.month, 1)
+    val gridStart = firstOfMonth.startOfGridWeek(weekStart)
+    val gridEnd = gridStart.plus(41, DateTimeUnit.DAY)
+    val start = gridStart.atStartOfDayIn(zone)
+    val end = gridEnd.atTime(23, 59, 59).toInstant(zone)
+    return start..end
+}
+
+internal fun LocalDate.startOfGridWeek(weekStart: DayOfWeek): LocalDate {
+    // DayOfWeek.ordinal: MONDAY=0..SUNDAY=6 → identical to ISO ordering.
+    val offset = ((dayOfWeek.ordinal - weekStart.ordinal) + 7) % 7
+    return minus(offset, DateTimeUnit.DAY)
+}

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

@@ -0,0 +1,719 @@
+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
+import androidx.compose.foundation.isSystemInDarkTheme
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.BoxWithConstraints
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.fillMaxHeight
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.offset
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.size
+import androidx.compose.foundation.layout.width
+import androidx.compose.foundation.ScrollState
+import androidx.compose.foundation.rememberScrollState
+import androidx.compose.foundation.shape.CircleShape
+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
+import androidx.compose.material3.ModalNavigationDrawer
+import androidx.compose.material3.Scaffold
+import androidx.compose.material3.Surface
+import androidx.compose.material3.Text
+import androidx.compose.material3.TopAppBar
+import androidx.compose.material3.TopAppBarDefaults
+import androidx.compose.material3.rememberDrawerState
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.LaunchedEffect
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableFloatStateOf
+import androidx.compose.runtime.mutableIntStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.rememberCoroutineScope
+import androidx.compose.runtime.snapshotFlow
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.draw.clip
+import androidx.compose.ui.draw.clipToBounds
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.RectangleShape
+import androidx.compose.ui.input.nestedscroll.nestedScroll
+import androidx.compose.ui.input.pointer.pointerInput
+import androidx.compose.ui.platform.LocalDensity
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.semantics.contentDescription
+import androidx.compose.ui.semantics.semantics
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.text.style.TextOverflow
+import androidx.compose.ui.unit.Dp
+import androidx.compose.ui.unit.dp
+import androidx.hilt.navigation.compose.hiltViewModel
+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.CalendarFailure
+import de.jeanlucmakiola.calendula.ui.common.CalendarView
+import de.jeanlucmakiola.calendula.ui.common.ViewSwitcherPill
+import de.jeanlucmakiola.calendula.ui.common.calendarSlideTransition
+import de.jeanlucmakiola.calendula.ui.common.currentLocale
+import de.jeanlucmakiola.calendula.ui.common.rememberCalendarSlideSpec
+import de.jeanlucmakiola.calendula.ui.common.next
+import de.jeanlucmakiola.calendula.ui.common.pastelize
+import kotlinx.coroutines.flow.first
+import kotlinx.coroutines.launch
+import kotlinx.datetime.DayOfWeek
+import kotlinx.datetime.LocalDate
+import kotlinx.datetime.plus
+import java.time.format.TextStyle as JavaTextStyle
+import java.util.Locale
+import kotlin.math.roundToInt
+
+private val HOUR_HEIGHT = 56.dp
+private val GUTTER_WIDTH = 48.dp
+private val MIN_EVENT_HEIGHT = 24.dp
+private val ALL_DAY_ROW_HEIGHT = 24.dp
+private val ALL_DAY_VERTICAL_PADDING = 6.dp
+
+/** Total all-day strip height for a week (0 when there are no all-day events). */
+private fun WeekUiState.Success.allDayStripHeight(): Dp {
+    if (allDaySpans.isEmpty()) return 0.dp
+    val lanes = allDaySpans.maxOf { it.lane } + 1
+    return ALL_DAY_ROW_HEIGHT * lanes + ALL_DAY_VERTICAL_PADDING * 2
+}
+
+@OptIn(ExperimentalMaterial3Api::class)
+@Composable
+fun WeekScreen(
+    selectedView: CalendarView,
+    onSelectView: (CalendarView) -> Unit,
+    onEventClick: (EventInstance) -> Unit,
+    modifier: Modifier = Modifier,
+    viewModel: WeekViewModel = hiltViewModel(),
+) {
+    val state by viewModel.state.collectAsStateWithLifecycle()
+    val weekStart by viewModel.weekStartDate.collectAsStateWithLifecycle()
+
+    val scrollBehavior = TopAppBarDefaults.pinnedScrollBehavior()
+    val drawerState = rememberDrawerState(DrawerValue.Closed)
+    val scope = rememberCoroutineScope()
+
+    // The static header + all-day strip share the app bar's scrolled colour so
+    // the whole top region elevates together once the timeline scrolls under it.
+    val topSectionColor by animateColorAsState(
+        targetValue = if (scrollBehavior.state.overlappedFraction > 0.01f) {
+            MaterialTheme.colorScheme.surfaceContainer
+        } else {
+            MaterialTheme.colorScheme.surface
+        },
+        label = "week-top-section-color",
+    )
+
+    val isOnCurrentWeek = when (val s = state) {
+        is WeekUiState.Success -> s.weekStart == s.today.startOfWeek(DayOfWeek.MONDAY)
+        else -> true
+    }
+
+    // Slide direction for the week transition: +1 = next, -1 = prev, 0 = jump.
+    var slideDir by remember { mutableIntStateOf(0) }
+    val goNext = { slideDir = 1; viewModel.goToNext() }
+    val goPrev = { slideDir = -1; viewModel.goToPrev() }
+    val jumpToToday = { slideDir = 0; viewModel.goToToday() }
+
+    ModalNavigationDrawer(
+        drawerState = drawerState,
+        // Open only via the menu button — edge-swipe would fight the week swipe.
+        gesturesEnabled = drawerState.isOpen,
+        drawerContent = {
+            CalendarDrawer(
+                onToday = { jumpToToday(); scope.launch { drawerState.close() } },
+                onJumpToDate = { scope.launch { drawerState.close() } /* TODO: date picker */ },
+                onFilter = { scope.launch { drawerState.close() } /* TODO: filter sheet */ },
+                onSettings = { scope.launch { drawerState.close() } /* TODO: settings */ },
+            )
+        },
+    ) {
+        Scaffold(
+            modifier = modifier.nestedScroll(scrollBehavior.nestedScrollConnection),
+            topBar = {
+                WeekTopBar(
+                    weekStart = weekStart,
+                    selectedView = selectedView,
+                    onCycleView = { onSelectView(selectedView.next()) },
+                    onOpenDrawer = { scope.launch { drawerState.open() } },
+                    scrollBehavior = scrollBehavior,
+                )
+            },
+            floatingActionButton = {
+                AnimatedVisibility(
+                    visible = !isOnCurrentWeek,
+                    enter = scaleIn(),
+                    exit = scaleOut(),
+                ) {
+                    ExtendedFloatingActionButton(
+                        onClick = jumpToToday,
+                        icon = { Icon(Icons.Default.Refresh, contentDescription = null) },
+                        text = { Text(stringResource(R.string.week_today_action)) },
+                    )
+                }
+            },
+        ) { innerPadding ->
+            WeekContent(
+                state = state,
+                slideDir = slideDir,
+                topSectionColor = topSectionColor,
+                onSwipeNext = goNext,
+                onSwipePrev = goPrev,
+                onRetry = jumpToToday,
+                onEventClick = onEventClick,
+                modifier = Modifier
+                    .padding(innerPadding)
+                    .fillMaxSize(),
+            )
+        }
+    }
+}
+
+@Composable
+private fun WeekContent(
+    state: WeekUiState,
+    slideDir: Int,
+    topSectionColor: Color,
+    onSwipeNext: () -> Unit,
+    onSwipePrev: () -> Unit,
+    onRetry: () -> Unit,
+    onEventClick: (EventInstance) -> Unit,
+    modifier: Modifier = Modifier,
+) {
+    val density = LocalDensity.current
+    val threshold = with(density) { 24.dp.toPx() }
+    var dragAccum by remember { mutableFloatStateOf(0f) }
+    val slideSpec = rememberCalendarSlideSpec()
+
+    // Hoisted above the per-week AnimatedContent so the vertical scroll position
+    // survives week-to-week swipes (e.g. 18:00 stays centred). We only centre on
+    // noon once, on first entry into the week view (i.e. when arriving from the
+    // month/day view), not on every swipe.
+    val scrollState = rememberScrollState()
+    LaunchedEffect(Unit) {
+        snapshotFlow { scrollState.maxValue }.first { it > 0 }
+        val maxV = scrollState.maxValue
+        val target = with(density) {
+            (HOUR_HEIGHT.toPx() * 12 - (HOUR_HEIGHT.toPx() * 24 - maxV) / 2f).roundToInt()
+        }.coerceIn(0, maxV)
+        scrollState.scrollTo(target)
+    }
+
+    // Single, hoisted all-day strip height — shared by the outgoing and incoming
+    // week during a swipe, so the strip slides along but never jumps in height;
+    // it just springs smoothly from the old to the new size.
+    val targetAllDayHeight = (state as? WeekUiState.Success)?.allDayStripHeight() ?: 0.dp
+    val allDayHeight by animateDpAsState(
+        targetValue = targetAllDayHeight,
+        label = "all-day-strip-height",
+    )
+
+    // Whole-page horizontal swipe. It sits one level above the timeline's
+    // vertical scroll: a horizontal drag only crosses *this* detector's slop,
+    // while a vertical drag is consumed by the inner scroll first — so the two
+    // gestures coexist without fighting.
+    val swipeModifier = Modifier.pointerInput(Unit) {
+        detectHorizontalDragGestures(
+            onDragStart = { dragAccum = 0f },
+            onDragEnd = {
+                when {
+                    dragAccum < -threshold -> onSwipeNext()
+                    dragAccum > threshold -> onSwipePrev()
+                }
+                dragAccum = 0f
+            },
+            onDragCancel = { dragAccum = 0f },
+            onHorizontalDrag = { _, drag -> dragAccum += drag },
+        )
+    }
+
+    AnimatedContent(
+        targetState = state,
+        modifier = modifier.then(swipeModifier),
+        contentKey = { s ->
+            when (s) {
+                is WeekUiState.Success -> "success-${s.weekStart}"
+                is WeekUiState.Failure -> "failure-${s.reason}"
+                WeekUiState.Loading -> "loading"
+            }
+        },
+        transitionSpec = { calendarSlideTransition(slideDir, slideSpec) },
+        label = "week-transition",
+    ) { s ->
+        when (s) {
+            WeekUiState.Loading -> WeekLoading()
+            is WeekUiState.Failure -> CalendarFailure(reason = s.reason, onRetry = onRetry)
+            is WeekUiState.Success -> WeekSuccess(
+                state = s,
+                topSectionColor = topSectionColor,
+                scrollState = scrollState,
+                allDayHeight = allDayHeight,
+                onEventClick = onEventClick,
+            )
+        }
+    }
+}
+
+@Composable
+private fun WeekSuccess(
+    state: WeekUiState.Success,
+    topSectionColor: Color,
+    scrollState: ScrollState,
+    allDayHeight: Dp,
+    onEventClick: (EventInstance) -> Unit,
+) {
+    Column(modifier = Modifier.fillMaxSize()) {
+        Column(
+            modifier = Modifier
+                .fillMaxWidth()
+                .background(topSectionColor),
+        ) {
+            WeekDayHeader(days = state.days, today = state.today)
+            AllDayStrip(state = state, height = allDayHeight, onEventClick = onEventClick)
+        }
+        // Breathing room between the (colour-shifting) top section and the
+        // scrolling timeline below.
+        Spacer(Modifier.height(8.dp))
+        Timeline(state = state, scrollState = scrollState, onEventClick = onEventClick)
+    }
+}
+
+@OptIn(ExperimentalMaterial3Api::class)
+@Composable
+private fun WeekTopBar(
+    weekStart: LocalDate,
+    selectedView: CalendarView,
+    onCycleView: () -> Unit,
+    onOpenDrawer: () -> Unit,
+    scrollBehavior: androidx.compose.material3.TopAppBarScrollBehavior,
+) {
+    TopAppBar(
+        title = {
+            Text(
+                text = formatWeekRange(weekStart),
+                style = MaterialTheme.typography.titleLarge,
+            )
+        },
+        navigationIcon = {
+            IconButton(onClick = onOpenDrawer) {
+                Icon(
+                    imageVector = Icons.Default.Menu,
+                    contentDescription = stringResource(R.string.month_open_menu),
+                )
+            }
+        },
+        actions = {
+            ViewSwitcherPill(
+                current = selectedView,
+                onCycle = onCycleView,
+                modifier = Modifier.padding(end = 8.dp),
+            )
+        },
+        // Match the static top section exactly: plain surface, lifting to
+        // surfaceContainer once content scrolls under the bar.
+        colors = TopAppBarDefaults.topAppBarColors(
+            containerColor = MaterialTheme.colorScheme.surface,
+            scrolledContainerColor = MaterialTheme.colorScheme.surfaceContainer,
+        ),
+        scrollBehavior = scrollBehavior,
+    )
+}
+
+@Composable
+private fun WeekDayHeader(days: List<LocalDate>, today: LocalDate) {
+    val locale = currentLocale()
+    val weekStart = days.first()
+    val weekNumber = remember(weekStart) {
+        java.time.LocalDate.of(weekStart.year, weekStart.month.ordinal + 1, weekStart.day)
+            .get(java.time.temporal.IsoFields.WEEK_OF_WEEK_BASED_YEAR)
+    }
+    Row(
+        modifier = Modifier
+            .fillMaxWidth()
+            .padding(top = 4.dp, bottom = 8.dp),
+    ) {
+        // Mirror the day-column layout (empty weekday line + spacer) so the
+        // badge lines up vertically with the date numbers.
+        Column(
+            modifier = Modifier.width(GUTTER_WIDTH),
+            horizontalAlignment = Alignment.CenterHorizontally,
+        ) {
+            Text(text = " ", style = MaterialTheme.typography.labelSmall)
+            Spacer(Modifier.height(2.dp))
+            WeekNumberBadge(weekNumber = weekNumber)
+        }
+        days.forEach { date ->
+            val javaDow = java.time.DayOfWeek.of(date.dayOfWeek.ordinal + 1)
+            val isToday = date == today
+            Column(
+                modifier = Modifier.weight(1f),
+                horizontalAlignment = Alignment.CenterHorizontally,
+            ) {
+                Text(
+                    text = javaDow.getDisplayName(JavaTextStyle.SHORT, locale),
+                    style = MaterialTheme.typography.labelSmall,
+                    color = MaterialTheme.colorScheme.onSurfaceVariant,
+                )
+                Spacer(Modifier.height(2.dp))
+                // Always reserve the 28dp circle slot so the header height is
+                // identical whether or not the week contains today.
+                Box(
+                    modifier = Modifier.size(28.dp),
+                    contentAlignment = Alignment.Center,
+                ) {
+                    if (isToday) {
+                        Surface(
+                            shape = CircleShape,
+                            color = MaterialTheme.colorScheme.primaryContainer,
+                            contentColor = MaterialTheme.colorScheme.onPrimaryContainer,
+                            modifier = Modifier.fillMaxSize(),
+                        ) {
+                            Box(contentAlignment = Alignment.Center) {
+                                Text(
+                                    text = date.day.toString(),
+                                    style = MaterialTheme.typography.titleSmall,
+                                    fontWeight = FontWeight.SemiBold,
+                                )
+                            }
+                        }
+                    } else {
+                        Text(
+                            text = date.day.toString(),
+                            style = MaterialTheme.typography.bodyMedium,
+                        )
+                    }
+                }
+            }
+        }
+    }
+}
+
+/** Calendar-week badge shown in the header gutter, deliberately set apart with a
+ *  filled box and bold number. */
+@Composable
+private fun WeekNumberBadge(weekNumber: Int, modifier: Modifier = Modifier) {
+    val label = stringResource(R.string.week_number_label)
+    Surface(
+        shape = RoundedCornerShape(8.dp),
+        color = MaterialTheme.colorScheme.secondaryContainer,
+        contentColor = MaterialTheme.colorScheme.onSecondaryContainer,
+        modifier = modifier.semantics { contentDescription = "$label $weekNumber" },
+    ) {
+        Text(
+            text = weekNumber.toString(),
+            style = MaterialTheme.typography.titleSmall,
+            fontWeight = FontWeight.Bold,
+            modifier = Modifier.padding(horizontal = 8.dp, vertical = 3.dp),
+        )
+    }
+}
+
+@Composable
+private fun AllDayStrip(
+    state: WeekUiState.Success,
+    height: Dp,
+    onEventClick: (EventInstance) -> Unit,
+) {
+    val dark = isSystemInDarkTheme()
+
+    Row(
+        modifier = Modifier
+            .fillMaxWidth()
+            // Height is hoisted + animated so it slides and resizes smoothly;
+            // padding sits inside it so the content area is lanes * row height.
+            .height(height)
+            .padding(vertical = ALL_DAY_VERTICAL_PADDING),
+    ) {
+        // Keep the gutter-width offset so the bars line up with the day columns.
+        Spacer(Modifier.width(GUTTER_WIDTH))
+        // Span bars are positioned absolutely so a multi-day event is one
+        // connected bar across columns rather than a chip per day. clipToBounds
+        // keeps bars from spilling out while the height animates.
+        BoxWithConstraints(
+            modifier = Modifier
+                .weight(1f)
+                .fillMaxHeight()
+                .clipToBounds(),
+        ) {
+            val colWidth = maxWidth / 7
+            state.allDaySpans.forEach { span ->
+                val spanCols = span.endCol - span.startCol + 1
+                AllDayBar(
+                    event = span.event,
+                    dark = dark,
+                    onClick = { onEventClick(span.event) },
+                    modifier = Modifier
+                        .offset(
+                            x = colWidth * span.startCol,
+                            y = ALL_DAY_ROW_HEIGHT * span.lane,
+                        )
+                        .width(colWidth * spanCols)
+                        .height(ALL_DAY_ROW_HEIGHT)
+                        .padding(horizontal = 1.dp, vertical = 1.dp),
+                )
+            }
+        }
+    }
+}
+
+@Composable
+private fun AllDayBar(
+    event: EventInstance,
+    dark: Boolean,
+    onClick: () -> Unit,
+    modifier: Modifier = Modifier,
+) {
+    val title = event.title.ifBlank { stringResource(R.string.event_untitled) }
+    Box(
+        modifier = modifier
+            .background(pastelize(event.color, dark), RoundedCornerShape(4.dp))
+            .clickable(onClick = onClick)
+            .padding(horizontal = 6.dp, vertical = 2.dp)
+            .semantics { contentDescription = title },
+        contentAlignment = Alignment.CenterStart,
+    ) {
+        Text(
+            text = title,
+            style = MaterialTheme.typography.labelSmall,
+            maxLines = 1,
+            overflow = TextOverflow.Ellipsis,
+            color = Color.Black.copy(alpha = 0.8f),
+        )
+    }
+}
+
+@Composable
+private fun Timeline(
+    state: WeekUiState.Success,
+    scrollState: ScrollState,
+    onEventClick: (EventInstance) -> Unit,
+) {
+    val totalHeight = HOUR_HEIGHT * 24
+    val dark = isSystemInDarkTheme()
+
+    Box(modifier = Modifier.fillMaxSize()) {
+        // Gutter and day columns are two scroll viewports that SHARE one scroll
+        // state, so they stay perfectly aligned. The day-column viewport is a
+        // static, rounded-clipped window — the content scrolls inside it, so the
+        // soft corners are permanent at any scroll position (not just at the
+        // day's start/end).
+        Row(modifier = Modifier.fillMaxSize()) {
+            // Hour gutter (scrolls in sync with the day columns)
+            Column(
+                modifier = Modifier
+                    .width(GUTTER_WIDTH)
+                    .fillMaxHeight()
+                    .verticalScroll(scrollState),
+            ) {
+                (0 until 24).forEach { h ->
+                    Box(
+                        modifier = Modifier
+                            .fillMaxWidth()
+                            .height(HOUR_HEIGHT),
+                    ) {
+                        if (h > 0) {
+                            Text(
+                                text = "%02d".format(h),
+                                style = MaterialTheme.typography.labelSmall,
+                                color = MaterialTheme.colorScheme.onSurfaceVariant,
+                                modifier = Modifier
+                                    .align(Alignment.TopCenter)
+                                    .offset(y = (-6).dp),
+                            )
+                        }
+                    }
+                }
+            }
+            // Day columns: rounded, clipped scroll viewport (permanent corners).
+            Box(
+                modifier = Modifier
+                    .weight(1f)
+                    .fillMaxHeight()
+                    .clip(RoundedCornerShape(16.dp))
+                    .verticalScroll(scrollState),
+            ) {
+                Row(
+                    modifier = Modifier
+                        .fillMaxWidth()
+                        .height(totalHeight),
+                    horizontalArrangement = Arrangement.spacedBy(2.dp),
+                ) {
+                    state.days.forEach { day ->
+                        DayColumnCard(
+                            blocks = state.timedByDay[day].orEmpty(),
+                            dark = dark,
+                            onEventClick = onEventClick,
+                            modifier = Modifier
+                                .weight(1f)
+                                .fillMaxHeight(),
+                        )
+                    }
+                }
+            }
+        }
+    }
+}
+
+@Composable
+private fun DayColumnCard(
+    blocks: List<TimedBlock>,
+    dark: Boolean,
+    onEventClick: (EventInstance) -> Unit,
+    modifier: Modifier = Modifier,
+) {
+    Card(
+        // Plain rectangular columns — the soft corners come from the outer
+        // rounded scroll viewport, so inner rounding would look odd at the edges.
+        shape = RectangleShape,
+        colors = CardDefaults.cardColors(
+            containerColor = MaterialTheme.colorScheme.surfaceContainer,
+        ),
+        modifier = modifier,
+    ) {
+        BoxWithConstraints(modifier = Modifier.fillMaxSize()) {
+            val colWidth = maxWidth
+            blocks.forEach { block ->
+                val laneWidth = colWidth / block.laneCount
+                val top = HOUR_HEIGHT * (block.startMin / 60f)
+                val rawHeight = HOUR_HEIGHT * ((block.endMin - block.startMin) / 60f)
+                val height = if (rawHeight < MIN_EVENT_HEIGHT) MIN_EVENT_HEIGHT else rawHeight
+                EventBlock(
+                    block = block,
+                    dark = dark,
+                    onClick = { onEventClick(block.event) },
+                    modifier = Modifier
+                        .offset(x = laneWidth * block.lane, y = top)
+                        .width(laneWidth)
+                        .height(height)
+                        .padding(horizontal = 1.dp),
+                )
+            }
+        }
+    }
+}
+
+@Composable
+private fun EventBlock(
+    block: TimedBlock,
+    dark: Boolean,
+    onClick: () -> Unit,
+    modifier: Modifier = Modifier,
+) {
+    val title = block.event.title.ifBlank { stringResource(R.string.event_untitled) }
+    val timeLabel = "${minToHm(block.startMin)}–${minToHm(block.endMin)}"
+    val showTime = block.endMin - block.startMin >= 45
+    Box(
+        modifier = modifier
+            .background(pastelize(block.event.color, dark), RoundedCornerShape(4.dp))
+            .clickable(onClick = onClick)
+            .padding(horizontal = 4.dp, vertical = 2.dp)
+            .semantics { contentDescription = "$title, $timeLabel" },
+    ) {
+        Column {
+            Text(
+                text = title,
+                style = MaterialTheme.typography.labelMedium,
+                maxLines = if (showTime) 1 else 2,
+                overflow = TextOverflow.Ellipsis,
+                color = Color.Black.copy(alpha = 0.85f),
+            )
+            if (showTime) {
+                // Narrow columns can't fit "13:00–14:00" on one line, so let it
+                // wrap to a second line (after the dash) instead of clipping the
+                // end time.
+                Text(
+                    text = timeLabel,
+                    style = MaterialTheme.typography.labelSmall,
+                    maxLines = 2,
+                    overflow = TextOverflow.Ellipsis,
+                    color = Color.Black.copy(alpha = 0.6f),
+                )
+            }
+        }
+    }
+}
+
+@Composable
+private fun WeekLoading() {
+    val totalHeight = HOUR_HEIGHT * 24
+    val scrollState = rememberScrollState()
+    Column(modifier = Modifier.fillMaxSize()) {
+        // Header skeleton
+        Row(modifier = Modifier.fillMaxWidth().padding(8.dp)) {
+            Spacer(Modifier.width(GUTTER_WIDTH))
+            repeat(7) {
+                Box(
+                    modifier = Modifier
+                        .weight(1f)
+                        .padding(horizontal = 2.dp)
+                        .height(36.dp)
+                        .background(
+                            MaterialTheme.colorScheme.surfaceContainer,
+                            RoundedCornerShape(8.dp),
+                        ),
+                )
+            }
+        }
+        Row(modifier = Modifier.fillMaxSize().verticalScroll(scrollState)) {
+            Spacer(Modifier.width(GUTTER_WIDTH))
+            repeat(7) {
+                Box(
+                    modifier = Modifier
+                        .weight(1f)
+                        .height(totalHeight)
+                        .padding(horizontal = 2.dp)
+                        .background(MaterialTheme.colorScheme.surfaceContainer),
+                )
+            }
+        }
+    }
+}
+
+private fun minToHm(min: Int): String =
+    if (min >= MINUTES_PER_DAY) "24:00" else "%02d:%02d".format(min / 60, min % 60)
+
+private fun formatWeekRange(weekStart: LocalDate): String {
+    val locale = Locale.getDefault()
+    val end = weekStart.plus(6, kotlinx.datetime.DateTimeUnit.DAY)
+    val monthName = { d: LocalDate ->
+        java.time.Month.of(d.month.ordinal + 1).getDisplayName(JavaTextStyle.SHORT, locale)
+    }
+    return if (weekStart.month == end.month && weekStart.year == end.year) {
+        "${weekStart.day}.–${end.day}. ${monthName(weekStart)} ${weekStart.year}"
+    } else if (weekStart.year == end.year) {
+        "${weekStart.day}. ${monthName(weekStart)} – ${end.day}. ${monthName(end)} ${end.year}"
+    } else {
+        "${weekStart.day}. ${monthName(weekStart)} ${weekStart.year} – " +
+            "${end.day}. ${monthName(end)} ${end.year}"
+    }
+}

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

@@ -0,0 +1,57 @@
+package de.jeanlucmakiola.calendula.ui.week
+
+import de.jeanlucmakiola.calendula.domain.EventInstance
+import de.jeanlucmakiola.calendula.domain.FailureReason
+import kotlinx.datetime.LocalDate
+
+/**
+ * One timed event clipped to a single day and assigned a horizontal lane so
+ * overlapping events render side-by-side (spec S2: "Overlap-Events nebeneinander
+ * aufgelöst").
+ *
+ * @param startMin minutes from this day's midnight, clamped to [0, 1440]
+ * @param endMin   minutes from this day's midnight, clamped to [startMin, 1440];
+ *                 equal to [startMin] for instant events (render enforces a
+ *                 minimum tap-target height)
+ * @param lane     0-based column within [laneCount]
+ * @param laneCount number of columns the event's overlap-cluster needs
+ */
+data class TimedBlock(
+    val event: EventInstance,
+    val startMin: Int,
+    val endMin: Int,
+    val lane: Int,
+    val laneCount: Int,
+)
+
+/**
+ * An all-day (or multi-day) event laid out as a single horizontal bar spanning
+ * [startCol]..[endCol] of the visible week, stacked on row [lane] so overlapping
+ * spans don't collide. A multi-day event is one connected bar — not one chip per
+ * day.
+ *
+ * @param startCol first visible covered column, 0..6 (clamped to the week)
+ * @param endCol   last visible covered column, 0..6, inclusive
+ * @param lane     0-based stacking row
+ */
+data class AllDaySpan(
+    val event: EventInstance,
+    val startCol: Int,
+    val endCol: Int,
+    val lane: Int,
+)
+
+sealed interface WeekUiState {
+    data object Loading : WeekUiState
+    data class Failure(val reason: FailureReason) : WeekUiState
+    data class Success(
+        val weekStart: LocalDate,
+        val today: LocalDate,
+        /** The seven days of the week, [weekStart] first. */
+        val days: List<LocalDate>,
+        /** All-day/multi-day events as connected horizontal spans. */
+        val allDaySpans: List<AllDaySpan>,
+        /** Timed events, clipped to each day with lanes resolved. */
+        val timedByDay: Map<LocalDate, List<TimedBlock>>,
+    ) : WeekUiState
+}

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

@@ -0,0 +1,227 @@
+package de.jeanlucmakiola.calendula.ui.week
+
+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.domain.CalendarSource
+import de.jeanlucmakiola.calendula.domain.EventInstance
+import de.jeanlucmakiola.calendula.domain.FailureReason
+import kotlinx.coroutines.CoroutineDispatcher
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+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.flatMapLatest
+import kotlinx.coroutines.flow.flowOn
+import kotlinx.coroutines.flow.stateIn
+import kotlinx.datetime.DateTimeUnit
+import kotlinx.datetime.DayOfWeek
+import kotlinx.datetime.LocalDate
+import kotlinx.datetime.TimeZone
+import kotlinx.datetime.atStartOfDayIn
+import kotlinx.datetime.atTime
+import kotlinx.datetime.minus
+import kotlinx.datetime.plus
+import kotlinx.datetime.toInstant
+import kotlinx.datetime.toLocalDateTime
+import kotlin.time.Clock
+import kotlin.time.Instant
+import javax.inject.Inject
+
+const val MINUTES_PER_DAY: Int = 24 * 60
+
+@OptIn(ExperimentalCoroutinesApi::class)
+@HiltViewModel
+class WeekViewModel @Inject constructor(
+    private val repository: CalendarRepository,
+    @IoDispatcher private val io: CoroutineDispatcher,
+) : ViewModel() {
+
+    private val zone = TimeZone.currentSystemDefault()
+
+    // V1: week starts Monday. DataStore-driven preference comes with Settings.
+    private val weekStart: DayOfWeek = DayOfWeek.MONDAY
+
+    private val todayDate: LocalDate
+        get() = Clock.System.now().toLocalDateTime(zone).date
+
+    private val _weekStartDate = MutableStateFlow(todayDate.startOfWeek(weekStart))
+    val weekStartDate: StateFlow<LocalDate> = _weekStartDate
+
+    val state: StateFlow<WeekUiState> = _weekStartDate
+        .flatMapLatest { start ->
+            val range = weekRange(start, zone)
+            combine(
+                repository.calendars(),
+                repository.instances(range),
+            ) { calendars, instances ->
+                buildState(start, calendars, instances)
+            }
+        }
+        .catch { emit(WeekUiState.Failure(FailureReason.ProviderUnavailable)) }
+        .flowOn(io)
+        .stateIn(
+            scope = viewModelScope,
+            started = SharingStarted.WhileSubscribed(5_000L),
+            initialValue = WeekUiState.Loading,
+        )
+
+    fun goToPrev() {
+        _weekStartDate.value = _weekStartDate.value.minus(7, DateTimeUnit.DAY)
+    }
+
+    fun goToNext() {
+        _weekStartDate.value = _weekStartDate.value.plus(7, DateTimeUnit.DAY)
+    }
+
+    fun goToToday() {
+        _weekStartDate.value = todayDate.startOfWeek(weekStart)
+    }
+
+    private fun buildState(
+        start: LocalDate,
+        calendars: List<CalendarSource>,
+        instances: List<EventInstance>,
+    ): WeekUiState {
+        if (calendars.isEmpty()) {
+            return WeekUiState.Failure(FailureReason.NoCalendarsConfigured)
+        }
+        val days = (0 until 7).map { start.plus(it, DateTimeUnit.DAY) }
+        val allDay = instances.filter { it.isAllDay }
+        val timed = instances.filterNot { it.isAllDay }
+        return WeekUiState.Success(
+            weekStart = start,
+            today = todayDate,
+            days = days,
+            allDaySpans = layoutAllDay(allDay, days, zone),
+            timedByDay = days.associateWith { day -> layoutDay(timed, day, zone) },
+        )
+    }
+}
+
+/**
+ * Lay out all-day events as connected horizontal spans across the visible week.
+ * Each event becomes one [AllDaySpan] from its first to its last covered column;
+ * overlapping spans are stacked on separate lanes (greedy first-fit by start).
+ */
+internal fun layoutAllDay(
+    events: List<EventInstance>,
+    days: List<LocalDate>,
+    zone: TimeZone,
+): List<AllDaySpan> {
+    data class Raw(val event: EventInstance, val startCol: Int, val endCol: Int)
+
+    val raw = events
+        .mapNotNull { ev ->
+            val covered = days.indices.filter { ev.coversDay(days[it], zone) }
+            if (covered.isEmpty()) null else Raw(ev, covered.first(), covered.last())
+        }
+        .sortedWith(compareBy({ it.startCol }, { it.endCol }))
+
+    val laneEnd = ArrayList<Int>() // last occupied column per lane
+    return raw.map { r ->
+        var lane = laneEnd.indexOfFirst { it < r.startCol }
+        if (lane == -1) {
+            laneEnd.add(r.endCol)
+            lane = laneEnd.size - 1
+        } else {
+            laneEnd[lane] = r.endCol
+        }
+        AllDaySpan(r.event, r.startCol, r.endCol, lane)
+    }
+}
+
+/** Beginning of the week (at [weekStart]) that contains this date. */
+internal fun LocalDate.startOfWeek(weekStart: DayOfWeek): LocalDate {
+    // DayOfWeek.ordinal: MONDAY=0..SUNDAY=6 → identical to ISO ordering.
+    val offset = ((dayOfWeek.ordinal - weekStart.ordinal) + 7) % 7
+    return minus(offset, DateTimeUnit.DAY)
+}
+
+/** Half-open instant range covering the seven days starting at [start]. */
+internal fun weekRange(start: LocalDate, zone: TimeZone): ClosedRange<Instant> {
+    val from = start.atStartOfDayIn(zone)
+    val to = start.plus(6, DateTimeUnit.DAY).atTime(23, 59, 59).toInstant(zone)
+    return from..to
+}
+
+/** True if this event overlaps the calendar [day] in [zone] (any portion). */
+internal fun EventInstance.coversDay(day: LocalDate, zone: TimeZone): Boolean {
+    val dayStart = day.atStartOfDayIn(zone)
+    val dayEnd = day.plus(1, DateTimeUnit.DAY).atStartOfDayIn(zone)
+    return start < dayEnd && end > dayStart
+}
+
+/**
+ * Clip [events] to a single [day] and assign lanes so overlapping events render
+ * side-by-side. Lane count is computed per overlap-cluster (a maximal run of
+ * chained-overlapping events), matching the common phone week-view behaviour.
+ *
+ * All-day events are ignored here — they live in the all-day strip.
+ */
+internal fun layoutDay(
+    events: List<EventInstance>,
+    day: LocalDate,
+    zone: TimeZone,
+): List<TimedBlock> {
+    val dayStart = day.atStartOfDayIn(zone)
+    val dayEnd = day.plus(1, DateTimeUnit.DAY).atStartOfDayIn(zone)
+
+    data class Raw(val event: EventInstance, val startMin: Int, val endMin: Int)
+
+    val raw = events.asSequence()
+        .filterNot { it.isAllDay }
+        .mapNotNull { ev ->
+            if (ev.start == ev.end) {
+                // Instant event: keep only if the point falls inside this day.
+                if (ev.start < dayStart || ev.start >= dayEnd) return@mapNotNull null
+                val m = (ev.start - dayStart).inWholeMinutes.toInt().coerceIn(0, MINUTES_PER_DAY)
+                Raw(ev, m, m)
+            } else {
+                val s = maxOf(ev.start, dayStart)
+                val e = minOf(ev.end, dayEnd)
+                if (e <= s) return@mapNotNull null
+                val startMin = (s - dayStart).inWholeMinutes.toInt().coerceIn(0, MINUTES_PER_DAY)
+                val endMin = (e - dayStart).inWholeMinutes.toInt().coerceIn(startMin, MINUTES_PER_DAY)
+                Raw(ev, startMin, endMin)
+            }
+        }
+        .sortedWith(compareBy({ it.startMin }, { it.endMin }))
+        .toList()
+
+    val result = ArrayList<TimedBlock>(raw.size)
+    var i = 0
+    while (i < raw.size) {
+        // Grow a cluster of chained-overlapping events.
+        var clusterEnd = raw[i].endMin
+        var j = i + 1
+        while (j < raw.size && raw[j].startMin < clusterEnd) {
+            clusterEnd = maxOf(clusterEnd, raw[j].endMin)
+            j++
+        }
+        val cluster = raw.subList(i, j)
+        // Greedy first-fit column assignment (= max overlap depth in the cluster).
+        val laneEnd = ArrayList<Int>()
+        val lanes = IntArray(cluster.size)
+        cluster.forEachIndexed { k, r ->
+            var placed = laneEnd.indexOfFirst { it <= r.startMin }
+            if (placed == -1) {
+                laneEnd.add(r.endMin)
+                placed = laneEnd.size - 1
+            } else {
+                laneEnd[placed] = r.endMin
+            }
+            lanes[k] = placed
+        }
+        val laneCount = laneEnd.size
+        cluster.forEachIndexed { k, r ->
+            result.add(TimedBlock(r.event, r.startMin, r.endMin, lanes[k], laneCount))
+        }
+        i = j
+    }
+    return result
+}

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

@@ -20,10 +20,59 @@
     <string name="permission_open_settings_button">System-Einstellungen öffnen</string>
     <string name="permission_retry_button">Erneut versuchen</string>
 
-    <!-- Debug-Screen (wegwerfbar — entfällt mit Plan 03) -->
+    <!-- Monatsansicht (S1) -->
-    <string name="debug_banner">DEBUG — wird mit Plan 03 durch die Monatsansicht ersetzt</string>
+    <string name="month_prev">Vorheriger Monat</string>
-    <string name="debug_calendars_header">Kalender</string>
+    <string name="month_next">Nächster Monat</string>
-    <string name="debug_events_header">Nächste 50 Termine</string>
+    <string name="month_today_action">Heute</string>
-    <string name="debug_no_calendars">Keine Kalender eingerichtet. Füge einen über DAVx5 oder die System-Einstellungen hinzu.</string>
+    <string name="month_more_actions">Weitere Aktionen</string>
-    <string name="debug_no_events">Keine anstehenden Termine in den nächsten 30 Tagen.</string>
+    <string name="month_open_menu">Menü öffnen</string>
+    <string name="month_action_filter">Kalender</string>
+    <string name="month_action_jump_to_date">Zu Datum springen…</string>
+    <string name="month_action_settings">Einstellungen</string>
+    <string name="month_a11y_today_prefix">Heute</string>
+
+    <!-- Wochenansicht (S2) -->
+    <string name="week_today_action">Diese Woche</string>
+    <string name="week_number_label">KW</string>
+
+    <!-- Tagesansicht (S3) -->
+    <string name="day_today_action">Heute</string>
+
+    <!-- Event-Detail-Screen (S4) -->
+    <string name="event_detail_back">Zurück</string>
+    <string name="event_detail_edit">Bearbeiten</string>
+    <string name="event_detail_delete">Löschen</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>
+    <string name="event_detail_location">Ort</string>
+    <string name="event_detail_description">Beschreibung</string>
+    <string name="event_detail_attendees">Teilnehmer</string>
+    <string name="event_detail_recurrence">Wiederholung</string>
+    <string name="event_detail_recurring">Wiederkehrender Termin</string>
+    <string name="recurrence_daily">Jeden Tag</string>
+    <string name="recurrence_weekly">Jede Woche</string>
+    <string name="recurrence_monthly">Jeden Monat</string>
+    <string name="recurrence_yearly">Jedes Jahr</string>
+    <string name="recurrence_every_n_days">Alle %1$d Tage</string>
+    <string name="recurrence_every_n_weeks">Alle %1$d Wochen</string>
+    <string name="recurrence_every_n_months">Alle %1$d Monate</string>
+    <string name="recurrence_every_n_years">Alle %1$d Jahre</string>
+    <string name="recurrence_on_days">%1$s am %2$s</string>
+    <string name="recurrence_with_until">%1$s bis %2$s</string>
+    <string name="recurrence_with_count">%1$s, %2$d Mal</string>
+    <string name="event_detail_not_found">Dieser Termin existiert nicht mehr.</string>
+    <string name="event_attendee_accepted">Zugesagt</string>
+    <string name="event_attendee_declined">Abgesagt</string>
+    <string name="event_attendee_tentative">Vorläufig</string>
+    <string name="event_attendee_needs_action">Keine Antwort</string>
+    <string name="event_attendee_unknown">—</string>
+
+    <!-- Geteilte Event-Strings -->
+    <string name="event_untitled">(Ohne Titel)</string>
+
+    <!-- View-Switcher (M1) -->
+    <string name="view_month">Monat</string>
+    <string name="view_week">Woche</string>
+    <string name="view_day">Tag</string>
 </resources>

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

@@ -21,10 +21,59 @@
     <string name="permission_open_settings_button">Open system settings</string>
     <string name="permission_retry_button">Try again</string>
 
-    <!-- Debug screen (wegwerfbar — entfällt mit Plan 03) -->
+    <!-- Month view (S1) -->
-    <string name="debug_banner">DEBUG — replaced by month view in Plan 03</string>
+    <string name="month_prev">Previous month</string>
-    <string name="debug_calendars_header">Calendars</string>
+    <string name="month_next">Next month</string>
-    <string name="debug_events_header">Next 50 events</string>
+    <string name="month_today_action">Today</string>
-    <string name="debug_no_calendars">No calendars configured. Add one via DAVx5 or system settings.</string>
+    <string name="month_more_actions">More actions</string>
-    <string name="debug_no_events">No upcoming events in the next 30 days.</string>
+    <string name="month_open_menu">Open menu</string>
+    <string name="month_action_filter">Calendars</string>
+    <string name="month_action_jump_to_date">Jump to date…</string>
+    <string name="month_action_settings">Settings</string>
+    <string name="month_a11y_today_prefix">Today</string>
+
+    <!-- Week view (S2) -->
+    <string name="week_today_action">This week</string>
+    <string name="week_number_label">Wk</string>
+
+    <!-- Day view (S3) -->
+    <string name="day_today_action">Today</string>
+
+    <!-- Event detail screen (S4) -->
+    <string name="event_detail_back">Back</string>
+    <string name="event_detail_edit">Edit</string>
+    <string name="event_detail_delete">Delete</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>
+    <string name="event_detail_location">Location</string>
+    <string name="event_detail_description">Description</string>
+    <string name="event_detail_attendees">Attendees</string>
+    <string name="event_detail_recurrence">Recurrence</string>
+    <string name="event_detail_recurring">Repeating event</string>
+    <string name="recurrence_daily">Every day</string>
+    <string name="recurrence_weekly">Every week</string>
+    <string name="recurrence_monthly">Every month</string>
+    <string name="recurrence_yearly">Every year</string>
+    <string name="recurrence_every_n_days">Every %1$d days</string>
+    <string name="recurrence_every_n_weeks">Every %1$d weeks</string>
+    <string name="recurrence_every_n_months">Every %1$d months</string>
+    <string name="recurrence_every_n_years">Every %1$d years</string>
+    <string name="recurrence_on_days">%1$s on %2$s</string>
+    <string name="recurrence_with_until">%1$s until %2$s</string>
+    <string name="recurrence_with_count">%1$s, %2$d times</string>
+    <string name="event_detail_not_found">This event no longer exists.</string>
+    <string name="event_attendee_accepted">Accepted</string>
+    <string name="event_attendee_declined">Declined</string>
+    <string name="event_attendee_tentative">Tentative</string>
+    <string name="event_attendee_needs_action">No response</string>
+    <string name="event_attendee_unknown">—</string>
+
+    <!-- Shared event strings -->
+    <string name="event_untitled">(No title)</string>
+
+    <!-- View switcher (M1) -->
+    <string name="view_month">Month</string>
+    <string name="view_week">Week</string>
+    <string name="view_day">Day</string>
 </resources>

app/src/test/java/de/jeanlucmakiola/calendula/ui/debug/DebugViewModelTest.kt

@@ -1,114 +0,0 @@
-package de.jeanlucmakiola.calendula.ui.debug
-
-import app.cash.turbine.test
-import com.google.common.truth.Truth.assertThat
-import de.jeanlucmakiola.calendula.data.calendar.CalendarRepository
-import de.jeanlucmakiola.calendula.data.calendar.NoSuchEventException
-import de.jeanlucmakiola.calendula.domain.CalendarSource
-import de.jeanlucmakiola.calendula.domain.EventDetail
-import de.jeanlucmakiola.calendula.domain.EventInstance
-import kotlinx.coroutines.Dispatchers
-import kotlinx.coroutines.ExperimentalCoroutinesApi
-import kotlinx.coroutines.flow.Flow
-import kotlinx.coroutines.flow.MutableStateFlow
-import kotlinx.coroutines.test.UnconfinedTestDispatcher
-import kotlinx.coroutines.test.resetMain
-import kotlinx.coroutines.test.runTest
-import kotlinx.coroutines.test.setMain
-import kotlin.time.Instant
-import org.junit.jupiter.api.AfterEach
-import org.junit.jupiter.api.BeforeEach
-import org.junit.jupiter.api.Test
-
-@OptIn(ExperimentalCoroutinesApi::class)
-class DebugViewModelTest {
-
-    private val testDispatcher = UnconfinedTestDispatcher()
-
-    @BeforeEach
-    fun setUp() {
-        Dispatchers.setMain(testDispatcher)
-    }
-
-    @AfterEach
-    fun tearDown() {
-        Dispatchers.resetMain()
-    }
-
-    private class FakeRepo(
-        val calendarsFlow: MutableStateFlow<List<CalendarSource>> = MutableStateFlow(emptyList()),
-        val instancesFlow: MutableStateFlow<List<EventInstance>> = MutableStateFlow(emptyList()),
-    ) : CalendarRepository {
-        override fun calendars(): Flow<List<CalendarSource>> = calendarsFlow
-        override fun instances(range: ClosedRange<Instant>): Flow<List<EventInstance>> = instancesFlow
-        override suspend fun eventDetail(eventId: Long): EventDetail =
-            throw NoSuchEventException(eventId)
-    }
-
-    private fun makeCal(id: Long, name: String = "C $id"): CalendarSource =
-        CalendarSource(id, name, "x@y", "LOCAL", 0xFF112233.toInt(), true)
-
-    private fun makeEvent(id: Long, title: String = "E $id") = EventInstance(
-        instanceId = id, eventId = id, calendarId = 1L,
-        title = title,
-        start = Instant.fromEpochMilliseconds(0L),
-        end = Instant.fromEpochMilliseconds(60_000L),
-        isAllDay = false, color = 0xFF000000.toInt(), location = null,
-    )
-
-    @Test
-    fun `initial state value is Loading before any subscriber`() {
-        val repo = FakeRepo()
-        val vm = DebugViewModel(repo, testDispatcher)
-        assertThat(vm.state.value).isEqualTo(DebugUiState.Loading)
-    }
-
-    @Test
-    fun `Success contains calendars and capped events after subscription`() = runTest {
-        val repo = FakeRepo(
-            calendarsFlow = MutableStateFlow(listOf(makeCal(1L))),
-            instancesFlow = MutableStateFlow(listOf(makeEvent(10L, "X"))),
-        )
-        val vm = DebugViewModel(repo, testDispatcher)
-        vm.state.test {
-            val success = awaitItem() as DebugUiState.Success
-            assertThat(success.calendars.map { it.id }).containsExactly(1L)
-            assertThat(success.nextEvents.map { it.title }).containsExactly("X")
-            cancelAndIgnoreRemainingEvents()
-        }
-    }
-
-    @Test
-    fun `instances are capped at 50`() = runTest {
-        val repo = FakeRepo(
-            calendarsFlow = MutableStateFlow(listOf(makeCal(1L))),
-            instancesFlow = MutableStateFlow((1L..100L).map { makeEvent(it, "E$it") }),
-        )
-        val vm = DebugViewModel(repo, testDispatcher)
-        vm.state.test {
-            val success = awaitItem() as DebugUiState.Success
-            assertThat(success.nextEvents).hasSize(50)
-            assertThat(success.nextEvents.first().instanceId).isEqualTo(1L)
-            assertThat(success.nextEvents.last().instanceId).isEqualTo(50L)
-            cancelAndIgnoreRemainingEvents()
-        }
-    }
-
-    @Test
-    fun `state updates when repository emits new data`() = runTest {
-        val repo = FakeRepo()
-        val vm = DebugViewModel(repo, testDispatcher)
-        vm.state.test {
-            // Empty initial: combine fires once because both StateFlows have initial empty value
-            val empty = awaitItem() as DebugUiState.Success
-            assertThat(empty.calendars).isEmpty()
-            assertThat(empty.nextEvents).isEmpty()
-
-            repo.calendarsFlow.value = listOf(makeCal(1L), makeCal(2L))
-            val updated = awaitItem() as DebugUiState.Success
-            assertThat(updated.calendars.map { it.id }).containsExactly(1L, 2L).inOrder()
-
-            cancelAndIgnoreRemainingEvents()
-        }
-    }
-}

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

@@ -0,0 +1,179 @@
+package de.jeanlucmakiola.calendula.ui.week
+
+import com.google.common.truth.Truth.assertThat
+import de.jeanlucmakiola.calendula.domain.EventInstance
+import kotlinx.datetime.DateTimeUnit
+import kotlinx.datetime.DayOfWeek
+import kotlinx.datetime.LocalDate
+import kotlinx.datetime.TimeZone
+import kotlinx.datetime.atTime
+import kotlinx.datetime.plus
+import kotlinx.datetime.toInstant
+import kotlin.time.Instant
+import org.junit.jupiter.api.Test
+
+class WeekLayoutTest {
+
+    private val zone = TimeZone.UTC
+
+    // 2026-06-10 is a Wednesday; its Monday-anchored week starts 2026-06-08.
+    private val wed = LocalDate(2026, 6, 10)
+    private val mon = LocalDate(2026, 6, 8)
+    private val weekDays = (0..6).map { mon.plusDays(it) }
+
+    private fun at(date: LocalDate, h: Int, m: Int = 0): Instant =
+        date.atTime(h, m).toInstant(zone)
+
+    private fun event(
+        start: Instant,
+        end: Instant,
+        allDay: Boolean = false,
+        id: Long = 1L,
+        title: String = "E",
+    ) = EventInstance(
+        instanceId = id,
+        eventId = id,
+        calendarId = 1L,
+        title = title,
+        start = start,
+        end = end,
+        isAllDay = allDay,
+        color = 0xFF112233.toInt(),
+        location = null,
+    )
+
+    @Test
+    fun `startOfWeek snaps to monday`() {
+        assertThat(wed.startOfWeek(DayOfWeek.MONDAY)).isEqualTo(mon)
+        assertThat(mon.startOfWeek(DayOfWeek.MONDAY)).isEqualTo(mon)
+    }
+
+    @Test
+    fun `weekRange spans seven days`() {
+        val range = weekRange(mon, zone)
+        assertThat(range.start).isEqualTo(at(mon, 0, 0))
+        // endInclusive is the last second of day 7 (Sunday 2026-06-14)
+        assertThat(range.endInclusive).isEqualTo(LocalDate(2026, 6, 14).atTime(23, 59, 59).toInstant(zone))
+    }
+
+    @Test
+    fun `coversDay is true for any overlap and false otherwise`() {
+        val ev = event(at(wed, 9), at(wed, 10))
+        assertThat(ev.coversDay(wed, zone)).isTrue()
+        assertThat(ev.coversDay(mon, zone)).isFalse()
+
+        val multiDay = event(at(mon, 22), at(wed, 2), allDay = true)
+        assertThat(multiDay.coversDay(mon, zone)).isTrue()
+        assertThat(multiDay.coversDay(LocalDate(2026, 6, 9), zone)).isTrue()
+        assertThat(multiDay.coversDay(wed, zone)).isTrue()
+        assertThat(multiDay.coversDay(LocalDate(2026, 6, 12), zone)).isFalse()
+    }
+
+    @Test
+    fun `single timed event gets one lane`() {
+        val blocks = layoutDay(listOf(event(at(wed, 9), at(wed, 10, 30))), wed, zone)
+        assertThat(blocks).hasSize(1)
+        val b = blocks.single()
+        assertThat(b.startMin).isEqualTo(9 * 60)
+        assertThat(b.endMin).isEqualTo(10 * 60 + 30)
+        assertThat(b.lane).isEqualTo(0)
+        assertThat(b.laneCount).isEqualTo(1)
+    }
+
+    @Test
+    fun `overlapping events resolve to side-by-side lanes`() {
+        val a = event(at(wed, 9), at(wed, 11), id = 1L)
+        val b = event(at(wed, 10), at(wed, 12), id = 2L)
+        val blocks = layoutDay(listOf(a, b), wed, zone).sortedBy { it.lane }
+        assertThat(blocks.map { it.lane }).containsExactly(0, 1)
+        assertThat(blocks.all { it.laneCount == 2 }).isTrue()
+    }
+
+    @Test
+    fun `back-to-back events reuse one lane`() {
+        val a = event(at(wed, 9), at(wed, 10), id = 1L)
+        val b = event(at(wed, 10), at(wed, 11), id = 2L)
+        val blocks = layoutDay(listOf(a, b), wed, zone)
+        assertThat(blocks).hasSize(2)
+        assertThat(blocks.all { it.lane == 0 && it.laneCount == 1 }).isTrue()
+    }
+
+    @Test
+    fun `event spanning midnight is clipped to the day`() {
+        // Starts the previous evening, ends 02:00 on wed.
+        val ev = event(at(mon.plusDays(1), 22), at(wed, 2))
+        val blocks = layoutDay(listOf(ev), wed, zone)
+        assertThat(blocks).hasSize(1)
+        assertThat(blocks.single().startMin).isEqualTo(0)
+        assertThat(blocks.single().endMin).isEqualTo(2 * 60)
+    }
+
+    @Test
+    fun `instant event is kept with zero-length`() {
+        val ev = event(at(wed, 12), at(wed, 12))
+        val blocks = layoutDay(listOf(ev), wed, zone)
+        assertThat(blocks).hasSize(1)
+        assertThat(blocks.single().startMin).isEqualTo(12 * 60)
+        assertThat(blocks.single().endMin).isEqualTo(12 * 60)
+    }
+
+    @Test
+    fun `all-day events are excluded from the timed layout`() {
+        val ev = event(at(wed, 0), at(wed.plusDays(1), 0), allDay = true)
+        assertThat(layoutDay(listOf(ev), wed, zone)).isEmpty()
+    }
+
+    @Test
+    fun `events on other days are dropped`() {
+        val ev = event(at(mon, 9), at(mon, 10))
+        assertThat(layoutDay(listOf(ev), wed, zone)).isEmpty()
+    }
+
+    @Test
+    fun `single-day all-day event is a one-column span`() {
+        // Wed only: start Wed 00:00, end Thu 00:00.
+        val ev = event(at(weekDays[2], 0), at(weekDays[3], 0), allDay = true)
+        val spans = layoutAllDay(listOf(ev), weekDays, zone)
+        assertThat(spans).hasSize(1)
+        val s = spans.single()
+        assertThat(s.startCol).isEqualTo(2)
+        assertThat(s.endCol).isEqualTo(2)
+        assertThat(s.lane).isEqualTo(0)
+    }
+
+    @Test
+    fun `multi-day all-day event becomes one span across columns`() {
+        // Tue..Thu: end Fri 00:00 is exclusive, so Fri is not covered.
+        val ev = event(at(weekDays[1], 0), at(weekDays[4], 0), allDay = true)
+        val s = layoutAllDay(listOf(ev), weekDays, zone).single()
+        assertThat(s.startCol).isEqualTo(1)
+        assertThat(s.endCol).isEqualTo(3)
+    }
+
+    @Test
+    fun `span reaching outside the week is clamped to visible columns`() {
+        // Starts two days before Monday, ends Wed 00:00 → covers Mon..Tue.
+        val ev = event(at(mon.plusDays(-2), 0), at(weekDays[2], 0), allDay = true)
+        val s = layoutAllDay(listOf(ev), weekDays, zone).single()
+        assertThat(s.startCol).isEqualTo(0)
+        assertThat(s.endCol).isEqualTo(1)
+    }
+
+    @Test
+    fun `overlapping all-day spans get separate lanes`() {
+        val a = event(at(weekDays[0], 0), at(weekDays[3], 0), allDay = true, id = 1L) // Mon..Wed
+        val b = event(at(weekDays[1], 0), at(weekDays[4], 0), allDay = true, id = 2L) // Tue..Thu
+        val spans = layoutAllDay(listOf(a, b), weekDays, zone)
+        assertThat(spans.map { it.lane }.toSet()).isEqualTo(setOf(0, 1))
+    }
+
+    @Test
+    fun `disjoint all-day spans reuse one lane`() {
+        val a = event(at(weekDays[0], 0), at(weekDays[1], 0), allDay = true, id = 1L) // Mon
+        val b = event(at(weekDays[3], 0), at(weekDays[4], 0), allDay = true, id = 2L) // Thu
+        val spans = layoutAllDay(listOf(a, b), weekDays, zone)
+        assertThat(spans.all { it.lane == 0 }).isTrue()
+    }
+
+    private fun LocalDate.plusDays(n: Int): LocalDate = plus(n, DateTimeUnit.DAY)
+}

gradle/libs.versions.toml

@@ -41,6 +41,8 @@ androidx-ui-test-manifest = { group = "androidx.compose.ui", name = "ui-test-man
 
 # Material 3 (Expressive lives in this artifact for 1.5+)
 androidx-material3 = { group = "androidx.compose.material3", name = "material3", version.ref = "material3" }
+androidx-compose-material-icons-core = { group = "androidx.compose.material", name = "material-icons-core" }
+androidx-compose-material-icons-extended = { group = "androidx.compose.material", name = "material-icons-extended" }
 
 # Hilt
 hilt-android = { group = "com.google.dagger", name = "hilt-android", version.ref = "hilt" }