release: cut v1.0.0 — first public release

Version bumped to 1.0.0 / 7. No code changes beyond the version — 1.0.0 is the
accumulated v0.1 → v0.6 work (all V1 screens, full event read, filter, settings,
onboarding polish) declared release-ready. CHANGELOG [1.0.0] summarises the
shipped feature set; ROADMAP/STATE mark V1 complete.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.planning/REQUIREMENTS.md

@@ -17,7 +17,7 @@ See full design spec: `docs/superpowers/specs/2026-06-08-calendar-app-design.md`
 - [ ] Day view (S3)
 - [ ] Event Detail Sheet (S4)
 - [ ] Multi-Calendar Filter (M3)
-- [ ] Today button + Jump-to-Date (M2)
+- [x] Today button (M2) — shipped v0.5; Jump-to-Date **cut from scope**
 - [ ] View-Switcher (M1)
 - [ ] Settings screen (M4)
 - [ ] Empty / no-permission / no-calendars states

.planning/ROADMAP.md

@@ -6,15 +6,52 @@
 |---|---|---|
 | v0.1 | Foundation & CI | complete |
 | v0.2 | Data Layer & Permission Flow | complete |
-| v0.3 | Month view | in progress |
-| v0.4 | Week view | in progress |
-| v0.5 | Day view | pending |
-| v0.6 | Event Detail Sheet | pending |
-| v0.7 | Filter & Settings | pending |
+| v0.3 | Month + Week + Day views, view switcher | complete |
+| v0.4 | Event Detail (S4) + humanized recurrence | complete |
+| v0.5 | Calendar filter (M3) + Settings (M4) | complete |
+| v0.6 | Full event read — surface every readable field | complete |
+| v1.0 | First public release — polish pass, F-Droid | complete |
 
-## v1.0 — First Public Release
+Delivery ran ahead of the original table: Day view (S3) shipped in v0.3 and
+Event Detail (S4) in v0.4, so the Filter/Settings milestone became v0.5.
 
-All V1 features shipped, polished, on F-Droid. Read-only calendar.
+Jump-to-date (the date-picker half of M2) was **cut from scope** and will not
+ship. The "Today" half of M2 already shipped in v0.5 (drawer entry).
+
+## v0.6 — Full event read
+
+Round out the read-only model so a detail view shows everything the system
+actually stores, before write support starts. Scope = `CalendarContract`
+columns we don't yet read/display:
+
+- **Reminders** (`VALARM`) — read `CalendarContract.Reminders`, list lead times
+- **Status** — Confirmed / Tentative / Cancelled (cancelled shown struck-through)
+- **Availability** (`TRANSP`) — Free / Busy chip
+- **Attendee extras** — role (required / optional / organizer) + the user's own
+  `SELF_ATTENDEE_STATUS`
+- **Timezone** (`EVENT_TIMEZONE`) — shown only when it differs from the device zone
+- **URL** — ~~tappable link card~~ **cut**: `CalendarContract` exposes no
+  `Events.URL` column (only `CUSTOM_APP_URI`, an originating-app deep-link).
+  URLs are instead surfaced by linkifying the description text
+- **Access level / class** (private / confidential) — small chip (optional, trivial)
+
+All of the above shipped in v0.6.0 (2026-06-11).
+
+Deliberately out of v0.6:
+- Recurrence exception / modified-occurrence badges — `Instances` already
+  resolves correct per-occurrence times for display; this only matters for
+  editing, so it folds into v2
+- `CATEGORIES`, `ATTACH` — not reliably exposed by `CalendarContract`
+  (provider limitation, not our choice)
+
+## v1.0 — First Public Release — shipped 2026-06-11
+
+All V1 features shipped, polished, on F-Droid. Read-only calendar. Cut directly
+after v0.6 (full event read) plus the onboarding-screen polish pass.
+
+### Polish backlog (pre-1.0)
+- ~~Redesign the initial grant-access (permission) screen~~ — **done**
+  (Material 3 Expressive onboarding, shipped in v0.6.0 / v1.0.0)
 
 ## v2.0 — Write Support
 

.planning/STATE.md

@@ -1,12 +1,13 @@
 # Calendula — Current State
 
-*Last updated: 2026-06-10*
+*Last updated: 2026-06-11*
 
 ## Status
 
-**Milestone:** v0.4 — Week view (in progress)
-**Phase:** Month + Week views implemented; cross-cutting wiring (detail sheet,
-filter, settings, jump-to-date) still stubbed
+**Milestone:** v1.0.0 — First public release (shipped 2026-06-11)
+**Phase:** V1 is complete and released. All screens done, the read model
+surfaces every readable `CalendarContract` field, and the onboarding screen
+got its Material 3 Expressive polish pass. Next horizon is v2.0 (write support)
 
 ## Progress
 
@@ -16,13 +17,18 @@ filter, settings, jump-to-date) still stubbed
 - [x] Plan 02 written and executed — data layer + permission flow + debug screen
 - [x] Month view (S1) — 6-week grid, event dots, today marker, swipe nav, three states (replaces debug screen)
 - [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
+- [x] Day view (S3) — single-column slice reusing the week layout
+- [x] View-switcher (M1) wired — cycles Month ↔ Week ↔ Day
+- [x] Event-detail screen (S4) — full-screen, humanized recurrence
+- [x] Filter sheet (M3) — per-calendar visibility, grouped by account, persisted, applied centrally in the repository
+- [x] Settings (M4) — appearance (theme, dynamic colour, week start), language (per-app locales), about
+- [~] Jump-to-date (M2) — **cut from scope**; "Today" half shipped in v0.5, date-picker dropped
+- [x] Full event read (v0.6) — reminders, status, availability, access level,
+  attendee role + self-response, foreign timezone, and linkified description
+  URLs in the detail view; new domain enums + mapper unit tests. (A dedicated
+  URL field was cut — no `CalendarContract` column backs it.)
 
 ## Next
 
-1. Day view (S3) — slot it into the view-switcher cycle
-2. Event-detail sheet (S4) — wire month-day and week-event taps to it
-3. Revisit month/week UI polish + shared anchor-date continuity across views
+1. v1.0.0 released — monitor the F-Droid build/publish
+2. Plan v2.0 (write support: create / edit / delete, quick-add, conflict UX)

CHANGELOG.md

@@ -7,6 +7,111 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [1.0.0] — 2026-06-11
+
+First public release. Calendula is a read-only, Material 3 Expressive calendar
+that lives entirely on top of Android's `CalendarContract` — every calendar
+synced to the device (CalDAV via DAVx5, Google, local, WebCal, …) shows up
+automatically, with zero telemetry and no internet permission.
+
+### Highlights (accumulated across v0.1 → v0.6)
+- Month, week, and day views with a view switcher, swipe navigation, and
+  Loading / Failure / Success states on every screen
+- Full-screen event detail surfacing every readable `CalendarContract` field —
+  times, recurrence (humanised), location, description (with tappable links),
+  attendees + roles + your own response, reminders, status, availability,
+  access level, and foreign time zones
+- Per-calendar visibility filter (grouped by account, persisted) and a Settings
+  screen (theme, Material You dynamic colour, week start, app language)
+- Material 3 Expressive first-run onboarding for calendar access
+- German + English localization throughout
+
+### Changed
+- `versionName`/`versionCode` bumped to 1.0.0 / 7
+
+## [0.6.0] — 2026-06-11
+
+### Added
+- Full event read (v0.6): the detail screen now surfaces every readable
+  `CalendarContract` field that V1 had been dropping —
+  - **Reminders** — each configured lead time, humanised ("10 minutes before",
+    "1 day before", "At time of event"), read from `CalendarContract.Reminders`
+  - **Status** — Tentative / Cancelled chip under the title; a cancelled event
+    also strikes through its title (Confirmed shows no chip)
+  - **Availability** — a "Free" pill pinned top-right of the title when the
+    event doesn't block your time (`Events.AVAILABILITY`, the iCal TRANSP
+    field); the default "Busy" is left implicit to avoid noise on every event
+  - **Access level** — a Private / Confidential chip when the event isn't public
+  - **Attendee role** — organizer / optional / resource badge under each
+    attendee, plus the device user's own response ("Your response: …") from
+    `Events.SELF_ATTENDEE_STATUS`
+  - **Time zone** — shown only for timed events pinned to a zone other than the
+    device's, so cross-zone events read unambiguously
+  - **Linked URLs** — http(s) links in the description are now tappable
+- Domain model rounded out with `Reminder`, `EventStatus`, `Availability`,
+  `AccessLevel`, `AttendeeRelationship`, `AttendeeType`, and the attendee/self
+  status fields; mappers + unit tests cover every new column's integer codes
+
+### Changed
+- Redesigned the first-run grant-access screen — the onboarding a new user
+  sees. Material 3 Expressive layout: branded launcher-mark hero, an app-name
+  eyebrow, a benefit-led headline, three trust rows (on-device, every calendar,
+  no tracking) with tonal icon chips, a full-width filled CTA with a trailing
+  arrow, and a "Read-only · no internet permission" footnote (the app declares
+  only `READ_CALENDAR`). The denied/recovery state shares the same shell with a
+  lock-badged hero and Open-settings / Try-again actions
+- `versionName`/`versionCode` bumped to 0.6.0 / 6
+
+### Notes
+- A dedicated event **URL** field was dropped from scope: `CalendarContract`
+  has no `Events.URL` column (only `CUSTOM_APP_URI`, an app deep-link), so URLs
+  are surfaced by linkifying the description instead
+
+## [0.5.0] — 2026-06-10
+
+### Added
+- Calendar filter (M3): the navigation drawer now hosts the calendar list
+  inline — every calendar grouped by account, each with a colour swatch and a
+  visibility switch. Hiding a calendar is persisted app-side (DataStore,
+  separate from the system VISIBLE flag) and applied centrally in the
+  repository, so month/week/day re-filter live the moment a switch flips.
+  The drawer was trimmed to just Today, the calendar filter, and Settings
+  (the stubbed jump-to-date entry was removed; jump-to-date was later cut
+  from scope entirely)
+- Settings (M4): a full-screen destination with
+  - **Appearance** — theme (System / Light / Dark), Material You dynamic colour
+    (auto-disabled below Android 12), week start (Automatic / Monday / Sunday)
+  - **Language** — app language (System / Deutsch / English) via per-app
+    locales, persisted across cold starts down to Android 10
+  - **About** — version, license, and a link to the source on Gitea
+- Week-start preference now drives the month grid and week view; "Automatic"
+  follows the active locale (Monday in DE, Sunday in en-US)
+
+### Changed
+- Theme is driven by one activity-scoped settings source, so a theme or
+  dynamic-colour change applies app-wide immediately
+- `versionName`/`versionCode` bumped to 0.5.0 / 5 (the in-repo version had
+  lagged behind the release tags); the About screen reads it directly
+
+## [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

app/build.gradle.kts

@@ -23,8 +23,8 @@ android {
         applicationId = "de.jeanlucmakiola.calendula"
         minSdk = 29
         targetSdk = 36
-        versionCode = 1
-        versionName = "0.1.0"
+        versionCode = 7
+        versionName = "1.0.0"
 
         testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
     }
@@ -89,6 +89,7 @@ kotlin {
 
 dependencies {
     implementation(libs.androidx.core.ktx)
+    implementation(libs.androidx.appcompat)
     implementation(libs.androidx.lifecycle.runtime.ktx)
     implementation(libs.androidx.lifecycle.runtime.compose)
     implementation(libs.androidx.activity.compose)
@@ -99,6 +100,7 @@ dependencies {
     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/androidTest/java/de/jeanlucmakiola/calendula/data/calendar/CalendarRepositorySmokeTest.kt

@@ -1,10 +1,14 @@
 package de.jeanlucmakiola.calendula.data.calendar
 
 import android.Manifest
+import androidx.datastore.core.DataStore
+import androidx.datastore.preferences.core.PreferenceDataStoreFactory
+import androidx.datastore.preferences.core.Preferences
 import androidx.test.ext.junit.runners.AndroidJUnit4
 import androidx.test.platform.app.InstrumentationRegistry
 import androidx.test.rule.GrantPermissionRule
 import com.google.common.truth.Truth.assertThat
+import de.jeanlucmakiola.calendula.data.prefs.CalendarPrefs
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.flow.first
 import kotlinx.coroutines.runBlocking
@@ -24,7 +28,10 @@ class CalendarRepositorySmokeTest {
 
     private fun newRepo(): CalendarRepositoryImpl {
         val dataSource = AndroidCalendarDataSource(context)
-        return CalendarRepositoryImpl(dataSource, Dispatchers.IO)
+        val store: DataStore<Preferences> = PreferenceDataStoreFactory.create(
+            produceFile = { context.cacheDir.resolve("smoke_test_prefs.preferences_pb") },
+        )
+        return CalendarRepositoryImpl(dataSource, CalendarPrefs(store), Dispatchers.IO)
     }
 
     @Test

app/src/main/AndroidManifest.xml

@@ -23,6 +23,17 @@
                 <category android:name="android.intent.category.LAUNCHER" />
             </intent-filter>
         </activity>
+
+        <!-- Persists the per-app language (M4) on API < 33, where the platform
+             per-app-languages API is unavailable. On 33+ this is a no-op. -->
+        <service
+            android:name="androidx.appcompat.app.AppLocalesMetadataHolderService"
+            android:enabled="false"
+            android:exported="false">
+            <meta-data
+                android:name="autoStoreLocales"
+                android:value="true" />
+        </service>
     </application>
 
 </manifest>

app/src/main/java/de/jeanlucmakiola/calendula/MainActivity.kt

@@ -4,10 +4,16 @@ import android.os.Bundle
 import androidx.activity.ComponentActivity
 import androidx.activity.compose.setContent
 import androidx.activity.enableEdgeToEdge
+import androidx.compose.foundation.isSystemInDarkTheme
 import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.runtime.getValue
 import androidx.compose.ui.Modifier
+import androidx.hilt.navigation.compose.hiltViewModel
+import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import dagger.hilt.android.AndroidEntryPoint
+import de.jeanlucmakiola.calendula.data.prefs.ThemeMode
 import de.jeanlucmakiola.calendula.ui.RootScreen
+import de.jeanlucmakiola.calendula.ui.settings.SettingsViewModel
 import de.jeanlucmakiola.calendula.ui.theme.CalendulaTheme
 
 @AndroidEntryPoint
@@ -16,7 +22,19 @@ class MainActivity : ComponentActivity() {
         super.onCreate(savedInstanceState)
         enableEdgeToEdge()
         setContent {
-            CalendulaTheme {
+            // One activity-scoped SettingsViewModel drives both the theme here
+            // and the Settings screen, so a theme change applies app-wide at once.
+            val settingsViewModel: SettingsViewModel = hiltViewModel()
+            val settings by settingsViewModel.state.collectAsStateWithLifecycle()
+            val darkTheme = when (settings.themeMode) {
+                ThemeMode.SYSTEM -> isSystemInDarkTheme()
+                ThemeMode.LIGHT -> false
+                ThemeMode.DARK -> true
+            }
+            CalendulaTheme(
+                darkTheme = darkTheme,
+                dynamicColor = settings.dynamicColor,
+            ) {
                 RootScreen(modifier = Modifier.fillMaxSize())
             }
         }

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

@@ -13,6 +13,7 @@ import de.jeanlucmakiola.calendula.domain.Attendee
 import de.jeanlucmakiola.calendula.domain.CalendarSource
 import de.jeanlucmakiola.calendula.domain.EventDetail
 import de.jeanlucmakiola.calendula.domain.EventInstance
+import de.jeanlucmakiola.calendula.domain.Reminder
 import javax.inject.Inject
 import javax.inject.Singleton
 
@@ -62,13 +63,14 @@ class AndroidCalendarDataSource @Inject constructor(
 
     override fun eventDetail(eventId: Long): EventDetail? {
         val attendees = queryAttendees(eventId)
+        val reminders = queryReminders(eventId)
         return resolver.query(
             ContentUris.withAppendedId(CalendarContract.Events.CONTENT_URI, eventId),
             EventDetailProjection.COLUMNS,
             null, null, null,
         )?.use { c ->
             if (!c.moveToFirst()) null
-            else CursorColumnReader(c).toEventDetailCore(attendees)
+            else CursorColumnReader(c).toEventDetailCore(attendees, reminders)
         }
     }
 
@@ -98,6 +100,14 @@ class AndroidCalendarDataSource @Inject constructor(
         null,
     )?.use { c -> c.mapAll { CursorColumnReader(c).toAttendee() } } ?: emptyList()
 
+    private fun queryReminders(eventId: Long): List<Reminder> = resolver.query(
+        CalendarContract.Reminders.CONTENT_URI,
+        ReminderProjection.COLUMNS,
+        CalendarContract.Reminders.EVENT_ID + " = ?",
+        arrayOf(eventId.toString()),
+        null,
+    )?.use { c -> c.mapAll { CursorColumnReader(c).toReminder() } } ?: emptyList()
+
     private fun toCalendarSource(c: Cursor): CalendarSource = CursorColumnReader(c).toCalendarSource()
 
     /** Iterate every row and map; skips nothing. */

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

@@ -1,12 +1,14 @@
 package de.jeanlucmakiola.calendula.data.calendar
 
 import de.jeanlucmakiola.calendula.data.di.IoDispatcher
+import de.jeanlucmakiola.calendula.data.prefs.CalendarPrefs
 import de.jeanlucmakiola.calendula.domain.CalendarSource
 import de.jeanlucmakiola.calendula.domain.EventDetail
 import de.jeanlucmakiola.calendula.domain.EventInstance
 import kotlinx.coroutines.CoroutineDispatcher
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.MutableSharedFlow
+import kotlinx.coroutines.flow.combine
 import kotlinx.coroutines.flow.flow
 import kotlinx.coroutines.flow.flowOn
 import kotlinx.coroutines.flow.onStart
@@ -23,6 +25,7 @@ import javax.inject.Singleton
 @Singleton
 class CalendarRepositoryImpl @Inject constructor(
     private val dataSource: CalendarDataSource,
+    private val prefs: CalendarPrefs,
     @IoDispatcher private val io: CoroutineDispatcher,
 ) : CalendarRepository {
 
@@ -41,7 +44,13 @@ class CalendarRepositoryImpl @Inject constructor(
             .reQuery { dataSource.calendars() }
             .flowOn(io)
 
+    // Instances are filtered by the app-side hidden-calendar set (M3): an event
+    // is dropped whenever the user has hidden its calendar. Re-runs when the
+    // provider ticks *or* the hidden set changes — toggling a calendar in the
+    // filter sheet updates every view immediately. [calendars] stays unfiltered
+    // so the filter sheet can list and re-enable hidden calendars.
     override fun instances(range: ClosedRange<Instant>): Flow<List<EventInstance>> =
+        combine(
             ticks
                 .onStart { emit(Unit) }
                 .reQuery {
@@ -49,8 +58,12 @@ class CalendarRepositoryImpl @Inject constructor(
                         beginMillis = range.start.toEpochMillis(),
                         endMillis = range.endInclusive.toEpochMillis(),
                     )
-            }
-            .flowOn(io)
+                },
+            prefs.hiddenCalendarIds,
+        ) { instances, hidden ->
+            if (hidden.isEmpty()) instances
+            else instances.filterNot { it.calendarId in hidden }
+        }.flowOn(io)
 
     override suspend fun eventDetail(eventId: Long): EventDetail = withContext(io) {
         dataSource.eventDetail(eventId) ?: throw NoSuchEventException(eventId)

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

@@ -2,25 +2,45 @@ package de.jeanlucmakiola.calendula.data.calendar
 
 import android.provider.CalendarContract
 import android.util.Log
+import de.jeanlucmakiola.calendula.domain.AccessLevel
 import de.jeanlucmakiola.calendula.domain.Attendee
+import de.jeanlucmakiola.calendula.domain.AttendeeRelationship
 import de.jeanlucmakiola.calendula.domain.AttendeeStatus
+import de.jeanlucmakiola.calendula.domain.AttendeeType
+import de.jeanlucmakiola.calendula.domain.Availability
 import de.jeanlucmakiola.calendula.domain.EventDetail
 import de.jeanlucmakiola.calendula.domain.EventInstance
+import de.jeanlucmakiola.calendula.domain.EventStatus
+import de.jeanlucmakiola.calendula.domain.Reminder
+import de.jeanlucmakiola.calendula.domain.ReminderMethod
 
 private const val TAG = "EventDetailMapper"
 
-internal fun ColumnReader.toEventDetailCore(attendees: List<Attendee>): EventDetail? {
+internal fun ColumnReader.toEventDetailCore(
+    attendees: List<Attendee>,
+    reminders: List<Reminder>,
+): 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=$begin")
+
+    // Recurring events store DURATION instead of DTEND, so the series row's
+    // DTEND is null. Keep the event (end == begin); callers that opened a
+    // specific occurrence supply the real per-occurrence times from
+    // CalendarContract.Instances. Only a present-but-backwards DTEND is malformed.
+    val end = if (isNull(EventDetailProjection.IDX_DTEND)) {
+        begin
+    } else {
+        val rawEnd = getLong(EventDetailProjection.IDX_DTEND)
+        if (rawEnd < begin) {
+            Log.w(TAG, "Dropping event with dtend=$rawEnd < dtstart=$begin")
             return null
         }
+        rawEnd
+    }
 
     val rawTitle = getString(EventDetailProjection.IDX_TITLE)
     val title = if (rawTitle.isNullOrEmpty()) Fallbacks.UNTITLED_EVENT else rawTitle
@@ -44,12 +64,28 @@ internal fun ColumnReader.toEventDetailCore(attendees: List<Attendee>): EventDet
         location = getString(EventDetailProjection.IDX_LOCATION),
     )
 
+    // STATUS shares its 0 value with STATUS_TENTATIVE, so a missing column must
+    // be distinguished from a present 0 — an absent status means "just confirmed".
+    val status = if (isNull(EventDetailProjection.IDX_STATUS)) {
+        EventStatus.Confirmed
+    } else {
+        mapEventStatus(getInt(EventDetailProjection.IDX_STATUS))
+    }
+
     return EventDetail(
         instance = instance,
         description = getString(EventDetailProjection.IDX_DESCRIPTION),
         organizer = getString(EventDetailProjection.IDX_ORGANIZER),
         attendees = attendees,
         rrule = getString(EventDetailProjection.IDX_RRULE),
+        reminders = reminders,
+        status = status,
+        // BUSY and DEFAULT are both 0, so a null column folds into the same
+        // default these mappers already return — no isNull guard needed.
+        availability = mapAvailability(getInt(EventDetailProjection.IDX_AVAILABILITY)),
+        accessLevel = mapAccessLevel(getInt(EventDetailProjection.IDX_ACCESS_LEVEL)),
+        eventTimezone = getString(EventDetailProjection.IDX_EVENT_TIMEZONE),
+        selfStatus = mapAttendeeStatus(getInt(EventDetailProjection.IDX_SELF_ATTENDEE_STATUS)),
     )
 }
 
@@ -57,6 +93,13 @@ internal fun ColumnReader.toAttendee(): Attendee = Attendee(
     name = getString(AttendeeProjection.IDX_NAME).orEmpty(),
     email = getString(AttendeeProjection.IDX_EMAIL),
     status = mapAttendeeStatus(getInt(AttendeeProjection.IDX_STATUS)),
+    relationship = mapAttendeeRelationship(getInt(AttendeeProjection.IDX_RELATIONSHIP)),
+    type = mapAttendeeType(getInt(AttendeeProjection.IDX_TYPE)),
+)
+
+internal fun ColumnReader.toReminder(): Reminder = Reminder(
+    minutes = getInt(ReminderProjection.IDX_MINUTES),
+    method = mapReminderMethod(getInt(ReminderProjection.IDX_METHOD)),
 )
 
 internal fun mapAttendeeStatus(raw: Int): AttendeeStatus = when (raw) {
@@ -66,3 +109,46 @@ internal fun mapAttendeeStatus(raw: Int): AttendeeStatus = when (raw) {
     CalendarContract.Attendees.ATTENDEE_STATUS_INVITED -> AttendeeStatus.NeedsAction
     else -> AttendeeStatus.Unknown
 }
+
+internal fun mapAttendeeRelationship(raw: Int): AttendeeRelationship = when (raw) {
+    CalendarContract.Attendees.RELATIONSHIP_ORGANIZER -> AttendeeRelationship.Organizer
+    CalendarContract.Attendees.RELATIONSHIP_PERFORMER -> AttendeeRelationship.Performer
+    CalendarContract.Attendees.RELATIONSHIP_SPEAKER -> AttendeeRelationship.Speaker
+    CalendarContract.Attendees.RELATIONSHIP_ATTENDEE -> AttendeeRelationship.Attendee
+    else -> AttendeeRelationship.None
+}
+
+internal fun mapAttendeeType(raw: Int): AttendeeType = when (raw) {
+    CalendarContract.Attendees.TYPE_REQUIRED -> AttendeeType.Required
+    CalendarContract.Attendees.TYPE_OPTIONAL -> AttendeeType.Optional
+    CalendarContract.Attendees.TYPE_RESOURCE -> AttendeeType.Resource
+    else -> AttendeeType.None
+}
+
+internal fun mapEventStatus(raw: Int): EventStatus = when (raw) {
+    CalendarContract.Events.STATUS_CONFIRMED -> EventStatus.Confirmed
+    CalendarContract.Events.STATUS_TENTATIVE -> EventStatus.Tentative
+    CalendarContract.Events.STATUS_CANCELED -> EventStatus.Cancelled
+    else -> EventStatus.Confirmed
+}
+
+internal fun mapAvailability(raw: Int): Availability = when (raw) {
+    CalendarContract.Events.AVAILABILITY_FREE -> Availability.Free
+    CalendarContract.Events.AVAILABILITY_TENTATIVE -> Availability.Tentative
+    else -> Availability.Busy
+}
+
+internal fun mapAccessLevel(raw: Int): AccessLevel = when (raw) {
+    CalendarContract.Events.ACCESS_CONFIDENTIAL -> AccessLevel.Confidential
+    CalendarContract.Events.ACCESS_PRIVATE -> AccessLevel.Private
+    CalendarContract.Events.ACCESS_PUBLIC -> AccessLevel.Public
+    else -> AccessLevel.Default
+}
+
+internal fun mapReminderMethod(raw: Int): ReminderMethod = when (raw) {
+    CalendarContract.Reminders.METHOD_EMAIL -> ReminderMethod.Email
+    CalendarContract.Reminders.METHOD_SMS -> ReminderMethod.Sms
+    CalendarContract.Reminders.METHOD_ALARM -> ReminderMethod.Alarm
+    CalendarContract.Reminders.METHOD_ALERT -> ReminderMethod.Alert
+    else -> ReminderMethod.Default
+}

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

@@ -60,6 +60,11 @@ internal object EventDetailProjection {
         CalendarContract.Events.ALL_DAY,
         CalendarContract.Events.EVENT_LOCATION,
         CalendarContract.Events.CALENDAR_ID,
+        CalendarContract.Events.STATUS,
+        CalendarContract.Events.AVAILABILITY,
+        CalendarContract.Events.ACCESS_LEVEL,
+        CalendarContract.Events.EVENT_TIMEZONE,
+        CalendarContract.Events.SELF_ATTENDEE_STATUS,
     )
 
     const val IDX_EVENT_ID = 0
@@ -74,6 +79,11 @@ internal object EventDetailProjection {
     const val IDX_ALL_DAY = 9
     const val IDX_LOCATION = 10
     const val IDX_CALENDAR_ID = 11
+    const val IDX_STATUS = 12
+    const val IDX_AVAILABILITY = 13
+    const val IDX_ACCESS_LEVEL = 14
+    const val IDX_EVENT_TIMEZONE = 15
+    const val IDX_SELF_ATTENDEE_STATUS = 16
 }
 
 internal object AttendeeProjection {
@@ -81,11 +91,25 @@ internal object AttendeeProjection {
         CalendarContract.Attendees.ATTENDEE_NAME,
         CalendarContract.Attendees.ATTENDEE_EMAIL,
         CalendarContract.Attendees.ATTENDEE_STATUS,
+        CalendarContract.Attendees.ATTENDEE_RELATIONSHIP,
+        CalendarContract.Attendees.ATTENDEE_TYPE,
     )
 
     const val IDX_NAME = 0
     const val IDX_EMAIL = 1
     const val IDX_STATUS = 2
+    const val IDX_RELATIONSHIP = 3
+    const val IDX_TYPE = 4
+}
+
+internal object ReminderProjection {
+    val COLUMNS: Array<String> = arrayOf(
+        CalendarContract.Reminders.MINUTES,
+        CalendarContract.Reminders.METHOD,
+    )
+
+    const val IDX_MINUTES = 0
+    const val IDX_METHOD = 1
 }
 
 internal object Fallbacks {

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

@@ -0,0 +1,78 @@
+package de.jeanlucmakiola.calendula.data.prefs
+
+import androidx.datastore.core.DataStore
+import androidx.datastore.preferences.core.Preferences
+import androidx.datastore.preferences.core.booleanPreferencesKey
+import androidx.datastore.preferences.core.edit
+import androidx.datastore.preferences.core.stringPreferencesKey
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.map
+import kotlinx.datetime.DayOfWeek
+import java.time.temporal.WeekFields
+import java.util.Locale
+import javax.inject.Inject
+import javax.inject.Singleton
+
+/** Light/dark override. SYSTEM follows the device setting. */
+enum class ThemeMode { SYSTEM, LIGHT, DARK }
+
+/** Week-start override. AUTO derives the first day from the active locale. */
+enum class WeekStartPref { AUTO, MONDAY, SUNDAY }
+
+/**
+ * Resolve the preference to a concrete first-day-of-week. AUTO reads the
+ * locale's convention (e.g. Monday in DE, Sunday in en-US).
+ */
+fun WeekStartPref.resolveFirstDay(locale: Locale): DayOfWeek = when (this) {
+    WeekStartPref.MONDAY -> DayOfWeek.MONDAY
+    WeekStartPref.SUNDAY -> DayOfWeek.SUNDAY
+    // java.time.DayOfWeek.value is ISO 1..7 (Mon..Sun) — same numbering kotlinx uses.
+    WeekStartPref.AUTO -> DayOfWeek(WeekFields.of(locale).firstDayOfWeek.value)
+}
+
+/**
+ * Display settings (M4) persisted app-side: theme override, Material You
+ * dynamic colour, and week start. Language is handled separately through
+ * AppCompatDelegate (which persists its own per-app locale).
+ *
+ * Enum prefs round-trip by [Enum.name]; an unknown/garbage stored value falls
+ * back to the default rather than throwing (see SettingsPrefsTest).
+ */
+@Singleton
+class SettingsPrefs @Inject constructor(
+    private val store: DataStore<Preferences>,
+) {
+
+    val themeMode: Flow<ThemeMode> = store.data.map { prefs ->
+        prefs[THEME_MODE_KEY].toEnum(ThemeMode.SYSTEM)
+    }
+
+    val dynamicColor: Flow<Boolean> = store.data.map { prefs ->
+        prefs[DYNAMIC_COLOR_KEY] ?: true
+    }
+
+    val weekStart: Flow<WeekStartPref> = store.data.map { prefs ->
+        prefs[WEEK_START_KEY].toEnum(WeekStartPref.AUTO)
+    }
+
+    suspend fun setThemeMode(mode: ThemeMode) {
+        store.edit { it[THEME_MODE_KEY] = mode.name }
+    }
+
+    suspend fun setDynamicColor(enabled: Boolean) {
+        store.edit { it[DYNAMIC_COLOR_KEY] = enabled }
+    }
+
+    suspend fun setWeekStart(pref: WeekStartPref) {
+        store.edit { it[WEEK_START_KEY] = pref.name }
+    }
+
+    companion object {
+        internal val THEME_MODE_KEY = stringPreferencesKey("theme_mode")
+        internal val DYNAMIC_COLOR_KEY = booleanPreferencesKey("dynamic_color")
+        internal val WEEK_START_KEY = stringPreferencesKey("week_start")
+    }
+}
+
+private inline fun <reified E : Enum<E>> String?.toEnum(default: E): E =
+    this?.let { stored -> enumValues<E>().firstOrNull { it.name == stored } } ?: default

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

@@ -29,12 +29,34 @@ data class EventDetail(
     val organizer: String?,
     val attendees: List<Attendee>,
     val rrule: String?,
+    /** Reminders (VALARM) configured on the event, ascending lead time. */
+    val reminders: List<Reminder> = emptyList(),
+    /** Confirmed / Tentative / Cancelled (`Events.STATUS`). */
+    val status: EventStatus = EventStatus.Confirmed,
+    /** Busy / Free (`Events.AVAILABILITY`, the iCal TRANSP field). */
+    val availability: Availability = Availability.Busy,
+    /** Default / Private / Confidential / Public (`Events.ACCESS_LEVEL`). */
+    val accessLevel: AccessLevel = AccessLevel.Default,
+    /** Raw zone id (`Events.EVENT_TIMEZONE`), e.g. "Europe/Berlin"; null if unset. */
+    val eventTimezone: String? = null,
+    /** This device user's own response (`Events.SELF_ATTENDEE_STATUS`). */
+    val selfStatus: AttendeeStatus = AttendeeStatus.Unknown,
 )
 
 data class Attendee(
     val name: String,
     val email: String?,
     val status: AttendeeStatus,
+    /** Organizer / performer / speaker / plain attendee (`ATTENDEE_RELATIONSHIP`). */
+    val relationship: AttendeeRelationship = AttendeeRelationship.None,
+    /** Required / optional / resource (`ATTENDEE_TYPE`). */
+    val type: AttendeeType = AttendeeType.None,
+)
+
+data class Reminder(
+    /** Lead time before the event start, in minutes. `-1` means the provider default. */
+    val minutes: Int,
+    val method: ReminderMethod,
 )
 
 enum class AttendeeStatus {
@@ -45,6 +67,48 @@ enum class AttendeeStatus {
     Unknown,
 }
 
+enum class AttendeeRelationship {
+    Organizer,
+    Attendee,
+    Performer,
+    Speaker,
+    None,
+}
+
+enum class AttendeeType {
+    Required,
+    Optional,
+    Resource,
+    None,
+}
+
+enum class ReminderMethod {
+    Alert,
+    Email,
+    Sms,
+    Alarm,
+    Default,
+}
+
+enum class EventStatus {
+    Confirmed,
+    Tentative,
+    Cancelled,
+}
+
+enum class Availability {
+    Busy,
+    Free,
+    Tentative,
+}
+
+enum class AccessLevel {
+    Default,
+    Public,
+    Private,
+    Confidential,
+}
+
 enum class FailureReason {
     PermissionRevoked,
     NoCalendarsConfigured,

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

@@ -1,15 +1,28 @@
 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.settings.SettingsScreen
 import de.jeanlucmakiola.calendula.ui.week.WeekScreen
+import kotlinx.datetime.LocalDate
 
 /**
  * Holds the active top-level view (spec M1) and swaps between the calendar
@@ -18,24 +31,90 @@ import de.jeanlucmakiola.calendula.ui.week.WeekScreen
  */
 @Composable
 fun CalendarHost(modifier: Modifier = Modifier) {
-    var view by rememberSaveable { mutableStateOf(CalendarView.Month) }
+    var view by rememberSaveable { mutableStateOf(CalendarView.Week) }
     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
+    }
+
+    // Settings (M4) is hoisted here so it overlays whichever calendar view is
+    // active and survives view switches. (The calendar filter now lives inline
+    // in the navigation drawer, so no overlay state is needed for it.)
+    var showSettings by rememberSaveable { mutableStateOf(false) }
+    val onOpenSettings = { showSettings = true }
+
+    val slideSpec = rememberCalendarSlideSpec()
+
+    Box(modifier = modifier.fillMaxSize()) {
         when (view) {
             CalendarView.Week -> WeekScreen(
                 selectedView = view,
                 onSelectView = onSelectView,
-            modifier = modifier,
+                onEventClick = onEventClick,
+                onOpenSettings = onOpenSettings,
             )
             CalendarView.Day -> DayScreen(
                 selectedView = view,
                 onSelectView = onSelectView,
-            modifier = modifier,
+                onEventClick = onEventClick,
+                onOpenSettings = onOpenSettings,
+                initialDateIso = pendingDayIso,
             )
             CalendarView.Month -> MonthScreen(
                 selectedView = view,
                 onSelectView = onSelectView,
-            modifier = modifier,
+                onOpenDay = onOpenDay,
+                onOpenSettings = onOpenSettings,
+            )
+        }
+
+        // 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 },
                 )
             }
         }
+
+        // Settings (M4) — full-screen destination, slides over the calendar.
+        AnimatedVisibility(
+            visible = showSettings,
+            enter = slideInHorizontally(slideSpec) { it } + fadeIn(),
+            exit = slideOutHorizontally(slideSpec) { it } + fadeOut(),
+        ) {
+            SettingsScreen(onBack = { showSettings = false })
+        }
+    }
+}

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

@@ -1,9 +1,15 @@
 package de.jeanlucmakiola.calendula.ui.common
 
+import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.fillMaxHeight
 import androidx.compose.foundation.layout.height
 import androidx.compose.foundation.layout.padding
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.filled.Settings
+import androidx.compose.material.icons.filled.Today
 import androidx.compose.material3.HorizontalDivider
+import androidx.compose.material3.Icon
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.ModalDrawerSheet
 import androidx.compose.material3.NavigationDrawerItem
@@ -13,20 +19,28 @@ import androidx.compose.ui.Modifier
 import androidx.compose.ui.res.stringResource
 import androidx.compose.ui.unit.dp
 import de.jeanlucmakiola.calendula.R
+import de.jeanlucmakiola.calendula.ui.filter.CalendarFilterList
 
 /**
- * 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.
+ * Navigation drawer shared by every top-level calendar screen.
+ *
+ * Visual language (kept deliberately small so sizes don't drift):
+ *  - Drawer title — `titleLarge`
+ *  - Section headers (e.g. "Calendars") — `titleSmall`, primary, text only
+ *  - Nav items (Today / Settings) — Material `NavigationDrawerItem`
+ *    (`labelLarge` label + a single 24dp leading icon)
+ *
+ * Hosts the per-calendar visibility filter (M3) inline — the calendar list with
+ * its checkboxes lives here rather than in a separate sheet — plus the "today"
+ * jump and a Settings entry (M4). The host screen owns the drawer state.
  */
 @Composable
 fun CalendarDrawer(
     onToday: () -> Unit,
-    onJumpToDate: () -> Unit,
-    onFilter: () -> Unit,
     onSettings: () -> Unit,
 ) {
     ModalDrawerSheet {
+        Column(Modifier.fillMaxHeight()) {
             Text(
                 text = stringResource(R.string.app_name),
                 style = MaterialTheme.typography.titleLarge,
@@ -35,31 +49,42 @@ fun CalendarDrawer(
             HorizontalDivider()
             Spacer(Modifier.height(8.dp))
             NavigationDrawerItem(
+                icon = { Icon(Icons.Filled.Today, contentDescription = null) },
                 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()
+
+            // Calendars (M3) — visibility checkboxes, scrollable, takes the slack
+            // between the top actions and the pinned Settings entry.
+            DrawerSectionHeader(stringResource(R.string.filter_title))
+            CalendarFilterList(modifier = Modifier.weight(1f))
+
             HorizontalDivider()
             Spacer(Modifier.height(8.dp))
             NavigationDrawerItem(
+                icon = { Icon(Icons.Filled.Settings, contentDescription = null) },
                 label = { Text(stringResource(R.string.month_action_settings)) },
                 selected = false,
                 onClick = onSettings,
                 modifier = Modifier.padding(horizontal = 12.dp),
             )
+            Spacer(Modifier.height(8.dp))
         }
     }
+}
+
+/** Top-level grouping label in the drawer. Text only, so it never reads as a
+ *  tappable nav item. */
+@Composable
+private fun DrawerSectionHeader(text: String) {
+    Text(
+        text = text,
+        style = MaterialTheme.typography.titleSmall,
+        color = MaterialTheme.colorScheme.primary,
+        modifier = Modifier.padding(start = 28.dp, end = 28.dp, top = 16.dp, bottom = 8.dp),
+    )
+}

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

@@ -7,6 +7,7 @@ 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
@@ -105,12 +106,20 @@ private fun DayUiState.Success.allDayStripHeight(): Dp {
 fun DayScreen(
     selectedView: CalendarView,
     onSelectView: (CalendarView) -> Unit,
+    onEventClick: (EventInstance) -> Unit,
+    onOpenSettings: () -> 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()
@@ -144,9 +153,10 @@ fun DayScreen(
         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 */ },
+                onSettings = {
+                    onOpenSettings()
+                    scope.launch { drawerState.close() }
+                },
             )
         },
     ) {
@@ -182,6 +192,7 @@ fun DayScreen(
                 onSwipeNext = goNext,
                 onSwipePrev = goPrev,
                 onRetry = jumpToToday,
+                onEventClick = onEventClick,
                 modifier = Modifier
                     .padding(innerPadding)
                     .fillMaxSize(),
@@ -198,6 +209,7 @@ private fun DayContent(
     onSwipeNext: () -> Unit,
     onSwipePrev: () -> Unit,
     onRetry: () -> Unit,
+    onEventClick: (EventInstance) -> Unit,
     modifier: Modifier = Modifier,
 ) {
     val density = LocalDensity.current
@@ -265,6 +277,7 @@ private fun DayContent(
                 topSectionColor = topSectionColor,
                 scrollState = scrollState,
                 allDayHeight = allDayHeight,
+                onEventClick = onEventClick,
             )
         }
     }
@@ -276,6 +289,7 @@ private fun DaySuccess(
     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,
@@ -283,6 +297,7 @@ private fun DaySuccess(
         AllDayStrip(
             state = state,
             height = allDayHeight,
+            onEventClick = onEventClick,
             modifier = Modifier
                 .fillMaxWidth()
                 .background(topSectionColor),
@@ -290,7 +305,7 @@ private fun DaySuccess(
         // Breathing room between the (colour-shifting) top section and the
         // scrolling timeline below.
         Spacer(Modifier.height(8.dp))
-        Timeline(state = state, scrollState = scrollState)
+        Timeline(state = state, scrollState = scrollState, onEventClick = onEventClick)
     }
 }
 
@@ -337,6 +352,7 @@ private fun DayTopBar(
 private fun AllDayStrip(
     state: DayUiState.Success,
     height: Dp,
+    onEventClick: (EventInstance) -> Unit,
     modifier: Modifier = Modifier,
 ) {
     val dark = isSystemInDarkTheme()
@@ -364,6 +380,7 @@ private fun AllDayStrip(
                 AllDayBar(
                     event = span.event,
                     dark = dark,
+                    onClick = { onEventClick(span.event) },
                     modifier = Modifier
                         .offset(y = ALL_DAY_ROW_HEIGHT * span.lane)
                         .width(barWidth)
@@ -376,11 +393,17 @@ private fun AllDayStrip(
 }
 
 @Composable
-private fun AllDayBar(event: EventInstance, dark: Boolean, modifier: Modifier = Modifier) {
+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,
@@ -396,7 +419,11 @@ private fun AllDayBar(event: EventInstance, dark: Boolean, modifier: Modifier =
 }
 
 @Composable
-private fun Timeline(state: DayUiState.Success, scrollState: ScrollState) {
+private fun Timeline(
+    state: DayUiState.Success,
+    scrollState: ScrollState,
+    onEventClick: (EventInstance) -> Unit,
+) {
     val totalHeight = HOUR_HEIGHT * 24
     val dark = isSystemInDarkTheme()
 
@@ -443,6 +470,7 @@ private fun Timeline(state: DayUiState.Success, scrollState: ScrollState) {
                 DayColumnCard(
                     blocks = state.timed,
                     dark = dark,
+                    onEventClick = onEventClick,
                     modifier = Modifier
                         .fillMaxWidth()
                         .height(totalHeight),
@@ -456,6 +484,7 @@ private fun Timeline(state: DayUiState.Success, scrollState: ScrollState) {
 private fun DayColumnCard(
     blocks: List<TimedBlock>,
     dark: Boolean,
+    onEventClick: (EventInstance) -> Unit,
     modifier: Modifier = Modifier,
 ) {
     Card(
@@ -477,6 +506,7 @@ private fun DayColumnCard(
                 EventBlock(
                     block = block,
                     dark = dark,
+                    onClick = { onEventClick(block.event) },
                     modifier = Modifier
                         .offset(x = laneWidth * block.lane, y = top)
                         .width(laneWidth)
@@ -492,6 +522,7 @@ private fun DayColumnCard(
 private fun EventBlock(
     block: TimedBlock,
     dark: Boolean,
+    onClick: () -> Unit,
     modifier: Modifier = Modifier,
 ) {
     val title = block.event.title.ifBlank { stringResource(R.string.event_untitled) }
@@ -500,6 +531,7 @@ private fun EventBlock(
     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" },
     ) {

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

@@ -78,6 +78,11 @@ class DayViewModel @Inject constructor(
         _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>,

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

@@ -0,0 +1,755 @@
+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.ExperimentalLayoutApi
+import androidx.compose.foundation.layout.FlowRow
+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.Notifications
+import androidx.compose.material.icons.filled.People
+import androidx.compose.material.icons.filled.Place
+import androidx.compose.material.icons.filled.Public
+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.runtime.remember
+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.pluralStringResource
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.text.AnnotatedString
+import androidx.compose.ui.text.LinkAnnotation
+import androidx.compose.ui.text.SpanStyle
+import androidx.compose.ui.text.TextLinkStyles
+import androidx.compose.ui.text.buildAnnotatedString
+import androidx.compose.ui.text.font.FontStyle
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.text.style.TextDecoration
+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.AccessLevel
+import de.jeanlucmakiola.calendula.domain.Attendee
+import de.jeanlucmakiola.calendula.domain.AttendeeRelationship
+import de.jeanlucmakiola.calendula.domain.AttendeeStatus
+import de.jeanlucmakiola.calendula.domain.AttendeeType
+import de.jeanlucmakiola.calendula.domain.Availability
+import de.jeanlucmakiola.calendula.domain.EventInstance
+import de.jeanlucmakiola.calendula.domain.EventStatus
+import de.jeanlucmakiola.calendula.domain.Reminder
+import de.jeanlucmakiola.calendula.ui.common.CalendarFailure
+import de.jeanlucmakiola.calendula.ui.common.currentLocale
+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 row: title on the left, a "Free" pill pinned top-right when the
+        // event doesn't block your time. Busy is the default for nearly every
+        // event, so it's left implicit — only Free is worth surfacing. A
+        // cancelled event strikes through its title.
+        Row(verticalAlignment = Alignment.Top) {
+            Text(
+                text = instance.title.ifBlank { stringResource(R.string.event_untitled) },
+                style = MaterialTheme.typography.headlineMedium,
+                fontWeight = FontWeight.SemiBold,
+                textDecoration = if (detail.status == EventStatus.Cancelled) {
+                    TextDecoration.LineThrough
+                } else {
+                    null
+                },
+                modifier = Modifier.weight(1f),
+            )
+            if (detail.availability == Availability.Free) {
+                Spacer(Modifier.width(12.dp))
+                InfoChip(
+                    text = stringResource(R.string.event_availability_free),
+                    modifier = Modifier.padding(top = 6.dp),
+                )
+            }
+        }
+        Spacer(Modifier.height(10.dp))
+        Box(
+            modifier = Modifier
+                .width(48.dp)
+                .height(3.dp)
+                .background(accent, RoundedCornerShape(2.dp)),
+        )
+
+        // Status / access chips — shown only when noteworthy (Confirmed status
+        // and Default/Public access are the silent norm).
+        val hasStatusChips = detail.status != EventStatus.Confirmed ||
+            detail.accessLevel == AccessLevel.Private ||
+            detail.accessLevel == AccessLevel.Confidential
+        if (hasStatusChips) {
+            Spacer(Modifier.height(16.dp))
+            StatusChips(detail.status, detail.accessLevel)
+        }
+
+        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,
+                )
+            }
+        }
+
+        // Time zone — only when the event is timed and pinned to a zone other
+        // than the device's, so cross-zone events read unambiguously.
+        foreignTimeZoneLabel(detail.eventTimezone, instance.isAllDay, locale)?.let { tzLabel ->
+            Spacer(Modifier.height(gap))
+            DetailCard(
+                icon = Icons.Default.Public,
+                iconContentDescription = stringResource(R.string.event_detail_timezone),
+            ) {
+                Text(text = tzLabel, style = MaterialTheme.typography.titleMedium)
+            }
+        }
+
+        // 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). URLs are auto-linked.
+        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 = linkifyUrls(description, MaterialTheme.colorScheme.primary),
+                    style = MaterialTheme.typography.bodyMedium,
+                )
+            }
+        }
+
+        // Attendees (conditional). The user's own response leads the list, then
+        // each attendee with their role and reply.
+        detail.attendees.takeIf { it.isNotEmpty() }?.let { attendees ->
+            Spacer(Modifier.height(gap))
+            DetailCard(
+                icon = Icons.Default.People,
+                iconContentDescription = stringResource(R.string.event_detail_attendees),
+            ) {
+                if (detail.selfStatus != AttendeeStatus.Unknown) {
+                    Text(
+                        text = stringResource(
+                            R.string.event_detail_self_response,
+                            stringResource(attendeeStatusLabel(detail.selfStatus)),
+                        ),
+                        style = MaterialTheme.typography.labelLarge,
+                        color = MaterialTheme.colorScheme.primary,
+                    )
+                    Spacer(Modifier.height(8.dp))
+                }
+                attendees.forEach { AttendeeRow(it) }
+            }
+        }
+
+        // Reminders (conditional) — list each lead time before the event.
+        detail.reminders.takeIf { it.isNotEmpty() }?.let { reminders ->
+            Spacer(Modifier.height(gap))
+            DetailCard(
+                icon = Icons.Default.Notifications,
+                iconContentDescription = stringResource(R.string.event_detail_reminders),
+            ) {
+                reminders
+                    .distinctBy { it.minutes }
+                    .sortedBy { it.minutes }
+                    .forEach { reminder ->
+                        Text(
+                            text = reminderLeadText(reminder),
+                            style = MaterialTheme.typography.titleMedium,
+                            modifier = Modifier.padding(vertical = 2.dp),
+                        )
+                    }
+            }
+        }
+
+        // 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,
+    ) {
+        Column(modifier = Modifier.weight(1f)) {
+            Text(
+                text = attendee.name.ifBlank { attendee.email.orEmpty() },
+                style = MaterialTheme.typography.bodyMedium,
+            )
+            attendeeRoleLabel(attendee)?.let { roleRes ->
+                Text(
+                    text = stringResource(roleRes),
+                    style = MaterialTheme.typography.labelSmall,
+                    color = MaterialTheme.colorScheme.onSurfaceVariant,
+                )
+            }
+        }
+        Spacer(Modifier.width(8.dp))
+        Text(
+            text = stringResource(attendeeStatusLabel(attendee.status)),
+            style = MaterialTheme.typography.labelSmall,
+            color = MaterialTheme.colorScheme.onSurfaceVariant,
+        )
+    }
+}
+
+/** Status / access pills shown directly under the title accent. */
+@OptIn(ExperimentalLayoutApi::class)
+@Composable
+private fun StatusChips(status: EventStatus, accessLevel: AccessLevel) {
+    FlowRow(
+        horizontalArrangement = Arrangement.spacedBy(8.dp),
+        verticalArrangement = Arrangement.spacedBy(8.dp),
+    ) {
+        when (status) {
+            EventStatus.Cancelled -> InfoChip(
+                text = stringResource(R.string.event_status_cancelled),
+                container = MaterialTheme.colorScheme.errorContainer,
+                content = MaterialTheme.colorScheme.onErrorContainer,
+            )
+            EventStatus.Tentative -> InfoChip(
+                text = stringResource(R.string.event_status_tentative),
+                container = MaterialTheme.colorScheme.tertiaryContainer,
+                content = MaterialTheme.colorScheme.onTertiaryContainer,
+            )
+            EventStatus.Confirmed -> Unit
+        }
+
+        when (accessLevel) {
+            AccessLevel.Private -> InfoChip(text = stringResource(R.string.event_access_private))
+            AccessLevel.Confidential ->
+                InfoChip(text = stringResource(R.string.event_access_confidential))
+            AccessLevel.Default, AccessLevel.Public -> Unit
+        }
+    }
+}
+
+@Composable
+private fun InfoChip(
+    text: String,
+    modifier: Modifier = Modifier,
+    container: Color = MaterialTheme.colorScheme.surfaceContainerHighest,
+    content: Color = MaterialTheme.colorScheme.onSurfaceVariant,
+) {
+    Surface(color = container, shape = RoundedCornerShape(8.dp), modifier = modifier) {
+        Text(
+            text = text,
+            style = MaterialTheme.typography.labelMedium,
+            color = content,
+            modifier = Modifier.padding(horizontal = 10.dp, vertical = 5.dp),
+        )
+    }
+}
+
+@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 -------------------------------------------------------------
+
+// Observable locale read (shared helper) — avoids NonObservableLocale /
+// LocalContextConfigurationRead lint by going through LocalConfiguration.
+@Composable
+private fun currentDetailLocale(): Locale = currentLocale()
+
+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
+}
+
+/**
+ * The role badge shown under an attendee's name. Organizer wins over type;
+ * required attendees (the common case) get no badge to keep the list quiet.
+ */
+private fun attendeeRoleLabel(attendee: Attendee): Int? = when {
+    attendee.relationship == AttendeeRelationship.Organizer -> R.string.event_attendee_organizer
+    attendee.type == AttendeeType.Optional -> R.string.event_attendee_optional
+    attendee.type == AttendeeType.Resource -> R.string.event_attendee_resource
+    else -> null
+}
+
+/** Humanise a reminder's lead time, e.g. "10 minutes before" / "At time of event". */
+@Composable
+private fun reminderLeadText(reminder: Reminder): String {
+    val minutes = reminder.minutes
+    return when {
+        minutes < 0 -> stringResource(R.string.reminder_default)
+        minutes == 0 -> stringResource(R.string.reminder_at_time)
+        minutes % 10_080 == 0 -> {
+            val weeks = minutes / 10_080
+            pluralStringResource(R.plurals.reminder_weeks, weeks, weeks)
+        }
+        minutes % 1_440 == 0 -> {
+            val days = minutes / 1_440
+            pluralStringResource(R.plurals.reminder_days, days, days)
+        }
+        minutes % 60 == 0 -> {
+            val hours = minutes / 60
+            pluralStringResource(R.plurals.reminder_hours, hours, hours)
+        }
+        else -> pluralStringResource(R.plurals.reminder_minutes, minutes, minutes)
+    }
+}
+
+/**
+ * A localized label for [tz] (e.g. "Central European Time (Europe/Berlin)"),
+ * but only when the event is timed and pinned to a zone different from the
+ * device's. Returns null when there's nothing worth showing.
+ */
+private fun foreignTimeZoneLabel(tz: String?, isAllDay: Boolean, locale: Locale): String? {
+    if (isAllDay || tz.isNullOrBlank()) return null
+    val deviceZone = ZoneId.systemDefault().id
+    if (tz == deviceZone) return null
+    return try {
+        val zone = ZoneId.of(tz)
+        val name = zone.getDisplayName(JavaTextStyle.FULL, locale)
+        if (name == tz) tz else "$name ($tz)"
+    } catch (e: Exception) {
+        tz
+    }
+}
+
+/** Wrap http(s) URLs in [text] as tappable links tinted [linkColor]. */
+@Composable
+private fun linkifyUrls(text: String, linkColor: Color): AnnotatedString = remember(text, linkColor) {
+    val regex = Regex("""https?://\S+""")
+    val styles = TextLinkStyles(
+        style = SpanStyle(color = linkColor, textDecoration = TextDecoration.Underline),
+    )
+    buildAnnotatedString {
+        append(text)
+        for (match in regex.findAll(text)) {
+            // Trim trailing punctuation that commonly abuts a URL in prose.
+            val raw = match.value
+            val url = raw.trimEnd('.', ',', ';', ':', '!', '?', ')', ']', '"', '\'')
+            val end = match.range.first + url.length
+            addLink(LinkAnnotation.Url(url, styles), match.range.first, end)
+        }
+    }
+}
+
+/**
+ * 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/filter/CalendarFilterList.kt

@@ -0,0 +1,154 @@
+package de.jeanlucmakiola.calendula.ui.filter
+
+import androidx.compose.foundation.background
+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.PaddingValues
+import androidx.compose.foundation.layout.Row
+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.Checkbox
+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.res.stringResource
+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.domain.FailureReason
+import de.jeanlucmakiola.calendula.ui.common.pastelize
+
+/**
+ * Calendar-visibility filter (M3), rendered inline in the navigation drawer.
+ * Every calendar grouped by account, each with a colour swatch and a visibility
+ * switch; toggling writes straight to DataStore and every calendar view
+ * re-filters live. Three states (Loading / Failure / Success).
+ */
+@Composable
+fun CalendarFilterList(
+    modifier: Modifier = Modifier,
+    viewModel: FilterViewModel = hiltViewModel(),
+) {
+    val state by viewModel.state.collectAsStateWithLifecycle()
+    when (val s = state) {
+        FilterUiState.Loading -> FilterLoading(modifier)
+        is FilterUiState.Failure -> FilterMessage(s.reason, modifier)
+        is FilterUiState.Success -> FilterList(
+            groups = s.groups,
+            onSetVisible = viewModel::setVisible,
+            modifier = modifier,
+        )
+    }
+}
+
+@Composable
+private fun FilterList(
+    groups: List<AccountGroup>,
+    onSetVisible: (Long, Boolean) -> Unit,
+    modifier: Modifier = Modifier,
+) {
+    val dark = isSystemInDarkTheme()
+    LazyColumn(
+        modifier = modifier.fillMaxWidth(),
+        contentPadding = PaddingValues(vertical = 4.dp),
+    ) {
+        groups.forEach { group ->
+            item(key = "header-${group.account}") {
+                Text(
+                    text = group.account,
+                    style = MaterialTheme.typography.labelMedium,
+                    color = MaterialTheme.colorScheme.onSurfaceVariant,
+                    modifier = Modifier.padding(start = 28.dp, end = 28.dp, top = 12.dp, bottom = 4.dp),
+                )
+            }
+            items(group.calendars, key = { it.id }) { cal ->
+                CalendarToggleRow(
+                    row = cal,
+                    dark = dark,
+                    onCheckedChange = { onSetVisible(cal.id, it) },
+                )
+            }
+        }
+    }
+}
+
+@Composable
+private fun CalendarToggleRow(
+    row: CalendarRow,
+    dark: Boolean,
+    onCheckedChange: (Boolean) -> Unit,
+) {
+    Row(
+        modifier = Modifier
+            .fillMaxWidth()
+            .padding(horizontal = 28.dp, vertical = 6.dp),
+        verticalAlignment = Alignment.CenterVertically,
+        horizontalArrangement = Arrangement.spacedBy(16.dp),
+    ) {
+        Box(
+            modifier = Modifier
+                .size(14.dp)
+                .background(pastelize(row.color, dark), CircleShape),
+        )
+        Text(
+            text = row.displayName,
+            style = MaterialTheme.typography.bodyMedium,
+            modifier = Modifier.weight(1f),
+        )
+        Checkbox(
+            checked = row.visible,
+            onCheckedChange = onCheckedChange,
+        )
+    }
+}
+
+@Composable
+private fun FilterLoading(modifier: Modifier = Modifier) {
+    Column(
+        modifier = modifier.fillMaxWidth(),
+        verticalArrangement = Arrangement.spacedBy(8.dp),
+    ) {
+        repeat(4) {
+            Box(
+                modifier = Modifier
+                    .padding(horizontal = 28.dp)
+                    .fillMaxWidth()
+                    .height(36.dp)
+                    .background(
+                        MaterialTheme.colorScheme.surfaceContainerHigh,
+                        MaterialTheme.shapes.medium,
+                    ),
+            )
+        }
+    }
+}
+
+@Composable
+private fun FilterMessage(reason: FailureReason, modifier: Modifier = Modifier) {
+    val msg = when (reason) {
+        FailureReason.NoCalendarsConfigured -> R.string.state_failure_no_calendars
+        FailureReason.PermissionRevoked -> R.string.state_failure_permission
+        else -> R.string.state_failure_provider
+    }
+    Text(
+        text = stringResource(msg),
+        style = MaterialTheme.typography.bodyMedium,
+        color = MaterialTheme.colorScheme.onSurfaceVariant,
+        textAlign = TextAlign.Center,
+        modifier = modifier
+            .fillMaxWidth()
+            .padding(horizontal = 28.dp, vertical = 24.dp),
+    )
+}

app/src/main/java/de/jeanlucmakiola/calendula/ui/filter/FilterUiState.kt

@@ -0,0 +1,27 @@
+package de.jeanlucmakiola.calendula.ui.filter
+
+import de.jeanlucmakiola.calendula.domain.FailureReason
+
+/**
+ * State for the calendar-filter sheet (M3). The user toggles per-calendar
+ * visibility; the choice is persisted app-side (separate from the system's
+ * VISIBLE flag) and applied to every calendar view.
+ */
+sealed interface FilterUiState {
+    data object Loading : FilterUiState
+    data class Failure(val reason: FailureReason) : FilterUiState
+    data class Success(val groups: List<AccountGroup>) : FilterUiState
+}
+
+/** Calendars grouped under the account that owns them (Nextcloud / Local / …). */
+data class AccountGroup(
+    val account: String,
+    val calendars: List<CalendarRow>,
+)
+
+data class CalendarRow(
+    val id: Long,
+    val displayName: String,
+    val color: Int,
+    val visible: Boolean,
+)

app/src/main/java/de/jeanlucmakiola/calendula/ui/filter/FilterViewModel.kt

@@ -0,0 +1,85 @@
+package de.jeanlucmakiola.calendula.ui.filter
+
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewModelScope
+import dagger.hilt.android.lifecycle.HiltViewModel
+import de.jeanlucmakiola.calendula.data.calendar.CalendarRepository
+import de.jeanlucmakiola.calendula.data.di.IoDispatcher
+import de.jeanlucmakiola.calendula.data.prefs.CalendarPrefs
+import de.jeanlucmakiola.calendula.domain.CalendarSource
+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.first
+import kotlinx.coroutines.flow.flowOn
+import kotlinx.coroutines.flow.stateIn
+import kotlinx.coroutines.launch
+import javax.inject.Inject
+
+@HiltViewModel
+class FilterViewModel @Inject constructor(
+    private val repository: CalendarRepository,
+    private val prefs: CalendarPrefs,
+    @IoDispatcher private val io: CoroutineDispatcher,
+) : ViewModel() {
+
+    val state: StateFlow<FilterUiState> =
+        combine(
+            repository.calendars(),
+            prefs.hiddenCalendarIds,
+        ) { calendars, hidden ->
+            if (calendars.isEmpty()) {
+                FilterUiState.Failure(FailureReason.NoCalendarsConfigured)
+            } else {
+                FilterUiState.Success(groupByAccount(calendars, hidden))
+            }
+        }
+            .catch { emit(FilterUiState.Failure(FailureReason.ProviderUnavailable)) }
+            .flowOn(io)
+            .stateIn(
+                scope = viewModelScope,
+                started = SharingStarted.WhileSubscribed(5_000L),
+                initialValue = FilterUiState.Loading,
+            )
+
+    /** Show or hide a single calendar; persists the new hidden set. */
+    fun setVisible(calendarId: Long, visible: Boolean) {
+        viewModelScope.launch {
+            val current = prefs.hiddenCalendarIds.first()
+            val next = if (visible) current - calendarId else current + calendarId
+            if (next != current) prefs.setHiddenCalendarIds(next)
+        }
+    }
+}
+
+/**
+ * Group calendars under their owning account, preserving the provider's order
+ * within each group and ordering groups by first appearance. A calendar is
+ * "visible" when its id is *not* in [hidden].
+ */
+internal fun groupByAccount(
+    calendars: List<CalendarSource>,
+    hidden: Set<Long>,
+): List<AccountGroup> =
+    calendars
+        .groupBy { it.accountLabel() }
+        .map { (account, cals) ->
+            AccountGroup(
+                account = account,
+                calendars = cals.map { c ->
+                    CalendarRow(
+                        id = c.id,
+                        displayName = c.displayName,
+                        color = c.color,
+                        visible = c.id !in hidden,
+                    )
+                },
+            )
+        }
+
+/** Account header text: the account name, falling back to its type. */
+private fun CalendarSource.accountLabel(): String =
+    accountName.takeIf { it.isNotBlank() } ?: accountType.takeIf { it.isNotBlank() } ?: displayName

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

@@ -84,11 +84,14 @@ import java.util.Locale
 fun MonthScreen(
     selectedView: CalendarView,
     onSelectView: (CalendarView) -> Unit,
+    onOpenDay: (LocalDate) -> Unit,
+    onOpenSettings: () -> Unit,
     modifier: Modifier = Modifier,
     viewModel: MonthViewModel = hiltViewModel(),
 ) {
     val state by viewModel.state.collectAsStateWithLifecycle()
     val month by viewModel.month.collectAsStateWithLifecycle()
+    val weekStart by viewModel.weekStart.collectAsStateWithLifecycle()
 
     val scrollBehavior = TopAppBarDefaults.pinnedScrollBehavior()
     val drawerState = rememberDrawerState(DrawerValue.Closed)
@@ -125,9 +128,10 @@ fun MonthScreen(
                     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 */ },
+                onSettings = {
+                    onOpenSettings()
+                    scope.launch { drawerState.close() }
+                },
             )
         },
     ) {
@@ -161,13 +165,15 @@ fun MonthScreen(
                     .padding(innerPadding)
                     .fillMaxSize(),
             ) {
-                WeekdayHeader(weekStart = DayOfWeek.MONDAY)
+                WeekdayHeader(weekStart = weekStart)
                 MonthContent(
                     state = state,
+                    weekStart = weekStart,
                     slideDir = slideDir,
                     onSwipeNext = goNext,
                     onSwipePrev = goPrev,
                     onRetry = jumpToToday,
+                    onOpenDay = onOpenDay,
                 )
             }
         }
@@ -177,10 +183,12 @@ fun MonthScreen(
 @Composable
 private fun MonthContent(
     state: MonthUiState,
+    weekStart: DayOfWeek,
     slideDir: Int,
     onSwipeNext: () -> Unit,
     onSwipePrev: () -> Unit,
     onRetry: () -> Unit,
+    onOpenDay: (LocalDate) -> Unit,
 ) {
     val density = LocalDensity.current
     val threshold = with(density) { 6.dp.toPx() }
@@ -218,7 +226,11 @@ private fun MonthContent(
         when (s) {
             MonthUiState.Loading -> MonthGridLoading()
             is MonthUiState.Failure -> CalendarFailure(reason = s.reason, onRetry = onRetry)
-            is MonthUiState.Success -> MonthGrid(state = s, weekStart = DayOfWeek.MONDAY)
+            is MonthUiState.Success -> MonthGrid(
+                state = s,
+                weekStart = weekStart,
+                onOpenDay = onOpenDay,
+            )
         }
     }
 }
@@ -290,6 +302,7 @@ private fun WeekdayHeader(weekStart: DayOfWeek) {
 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)
@@ -323,6 +336,7 @@ private fun MonthGrid(
                             date = date,
                             isToday = date == state.today,
                             data = state.cells[date],
+                            onClick = { onOpenDay(date) },
                             modifier = Modifier.weight(1f),
                         )
                     } else {
@@ -340,6 +354,7 @@ private fun DayCard(
     date: LocalDate,
     isToday: Boolean,
     data: DayCellData?,
+    onClick: () -> Unit,
     modifier: Modifier = Modifier,
 ) {
     val todayPrefix = stringResource(R.string.month_a11y_today_prefix)
@@ -362,7 +377,7 @@ private fun DayCard(
     )
 
     Card(
-        onClick = { /* TODO: open the day view (S3) for this date */ },
+        onClick = onClick,
         interactionSource = interactionSource,
         shape = MaterialTheme.shapes.medium,
         colors = CardDefaults.cardColors(

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

@@ -5,6 +5,8 @@ import androidx.lifecycle.viewModelScope
 import dagger.hilt.android.lifecycle.HiltViewModel
 import de.jeanlucmakiola.calendula.data.calendar.CalendarRepository
 import de.jeanlucmakiola.calendula.data.di.IoDispatcher
+import de.jeanlucmakiola.calendula.data.prefs.SettingsPrefs
+import de.jeanlucmakiola.calendula.data.prefs.resolveFirstDay
 import de.jeanlucmakiola.calendula.domain.CalendarSource
 import de.jeanlucmakiola.calendula.domain.EventInstance
 import de.jeanlucmakiola.calendula.domain.FailureReason
@@ -17,6 +19,7 @@ import kotlinx.coroutines.flow.catch
 import kotlinx.coroutines.flow.combine
 import kotlinx.coroutines.flow.flatMapLatest
 import kotlinx.coroutines.flow.flowOn
+import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.flow.stateIn
 import kotlinx.datetime.DateTimeUnit
 import kotlinx.datetime.DayOfWeek
@@ -29,6 +32,7 @@ import kotlinx.datetime.minus
 import kotlinx.datetime.plus
 import kotlinx.datetime.toInstant
 import kotlinx.datetime.toLocalDateTime
+import java.util.Locale
 import kotlin.time.Clock
 import kotlin.time.Instant
 import javax.inject.Inject
@@ -37,13 +41,21 @@ import javax.inject.Inject
 @HiltViewModel
 class MonthViewModel @Inject constructor(
     private val repository: CalendarRepository,
+    settingsPrefs: SettingsPrefs,
     @IoDispatcher private val io: CoroutineDispatcher,
 ) : ViewModel() {
 
     private val zone = TimeZone.currentSystemDefault()
+    private val locale: Locale = Locale.getDefault()
 
-    // V1: week starts Monday. DataStore-driven preference comes with Settings.
-    private val weekStart: DayOfWeek = DayOfWeek.MONDAY
+    /** First day of the week, from the Settings preference (AUTO → locale). */
+    val weekStart: StateFlow<DayOfWeek> = settingsPrefs.weekStart
+        .map { it.resolveFirstDay(locale) }
+        .stateIn(
+            scope = viewModelScope,
+            started = SharingStarted.WhileSubscribed(5_000L),
+            initialValue = DayOfWeek.MONDAY,
+        )
 
     private val todayDate: LocalDate
         get() = Clock.System.now().toLocalDateTime(zone).date
@@ -51,9 +63,10 @@ class MonthViewModel @Inject constructor(
     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)
+    val state: StateFlow<MonthUiState> =
+        combine(_month, weekStart) { ym, ws -> ym to ws }
+            .flatMapLatest { (ym, ws) ->
+                val range = monthGridRange(ym, ws, zone)
                 combine(
                     repository.calendars(),
                     repository.instances(range),

app/src/main/java/de/jeanlucmakiola/calendula/ui/permission/PermissionScreen.kt

@@ -6,28 +6,65 @@ import android.net.Uri
 import android.provider.Settings
 import androidx.activity.compose.rememberLauncherForActivityResult
 import androidx.activity.result.contract.ActivityResultContracts
+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.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.navigationBarsPadding
+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.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.automirrored.filled.ArrowForward
+import androidx.compose.material.icons.filled.CalendarMonth
+import androidx.compose.material.icons.filled.Lock
+import androidx.compose.material.icons.filled.VisibilityOff
 import androidx.compose.material3.Button
+import androidx.compose.material3.ButtonDefaults
+import androidx.compose.material3.Icon
 import androidx.compose.material3.MaterialTheme
-import androidx.compose.material3.OutlinedButton
+import androidx.compose.material3.Scaffold
 import androidx.compose.material3.Text
+import androidx.compose.material3.TextButton
 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.draw.clip
+import androidx.compose.ui.graphics.vector.ImageVector
 import androidx.compose.ui.platform.LocalContext
+import androidx.compose.ui.res.colorResource
+import androidx.compose.ui.res.painterResource
 import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.text.style.TextAlign
 import androidx.compose.ui.unit.dp
+import androidx.compose.ui.unit.sp
 import androidx.hilt.navigation.compose.hiltViewModel
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
+import androidx.compose.foundation.Image
 import de.jeanlucmakiola.calendula.R
 
+// MD3 8dp spacing scale, scoped to this screen.
+private object Space {
+    val xs = 8.dp
+    val sm = 16.dp
+    val md = 24.dp
+    val lg = 32.dp
+    val xl = 48.dp
+}
+
 @Composable
 fun PermissionScreen(
     onGranted: () -> Unit,
@@ -69,24 +106,68 @@ private fun RationaleContent(
     onRequest: () -> Unit,
     modifier: Modifier = Modifier,
 ) {
-    Column(
-        modifier = modifier.fillMaxSize().padding(24.dp),
-        verticalArrangement = Arrangement.Center,
-        horizontalAlignment = Alignment.CenterHorizontally,
+    PermissionScaffold(
+        modifier = modifier,
+        hero = { BrandHero(denied = false) },
+        actions = {
+            Button(
+                onClick = onRequest,
+                modifier = Modifier.fillMaxWidth().height(56.dp),
+                contentPadding = ButtonDefaults.ButtonWithIconContentPadding,
             ) {
+                Text(
+                    text = stringResource(R.string.permission_request_button),
+                    style = MaterialTheme.typography.titleMedium,
+                )
+                Spacer(Modifier.width(Space.xs))
+                Icon(
+                    imageVector = Icons.AutoMirrored.Filled.ArrowForward,
+                    contentDescription = null,
+                    modifier = Modifier.size(20.dp),
+                )
+            }
+            PrivacyFootnote()
+        },
+    ) {
+        Text(
+            text = stringResource(R.string.app_name).uppercase(),
+            style = MaterialTheme.typography.labelLarge,
+            color = MaterialTheme.colorScheme.primary,
+            letterSpacing = 2.sp,
+        )
+        Spacer(Modifier.height(Space.xs))
         Text(
             text = stringResource(R.string.permission_rationale_title),
             style = MaterialTheme.typography.headlineMedium,
+            textAlign = TextAlign.Center,
         )
-        Spacer(Modifier.height(16.dp))
+        Spacer(Modifier.height(12.dp))
         Text(
             text = stringResource(R.string.permission_rationale_body),
             style = MaterialTheme.typography.bodyLarge,
+            color = MaterialTheme.colorScheme.onSurfaceVariant,
+            textAlign = TextAlign.Center,
+        )
+
+        Spacer(Modifier.height(Space.xl))
+
+        BenefitRow(
+            icon = Icons.Filled.Lock,
+            title = stringResource(R.string.permission_benefit_private_title),
+            body = stringResource(R.string.permission_benefit_private_body),
+        )
+        Spacer(Modifier.height(Space.sm))
+        BenefitRow(
+            icon = Icons.Filled.CalendarMonth,
+            title = stringResource(R.string.permission_benefit_sync_title),
+            body = stringResource(R.string.permission_benefit_sync_body),
+        )
+        Spacer(Modifier.height(Space.sm))
+        BenefitRow(
+            icon = Icons.Filled.VisibilityOff,
+            title = stringResource(R.string.permission_benefit_privacy_title),
+            body = stringResource(R.string.permission_benefit_privacy_body),
         )
-        Spacer(Modifier.height(32.dp))
-        Button(onClick = onRequest) {
-            Text(stringResource(R.string.permission_request_button))
-        }
     }
 }
 
@@ -96,26 +177,11 @@ private fun DeniedContent(
     modifier: Modifier = Modifier,
 ) {
     val context = LocalContext.current
-    Column(
-        modifier = modifier.fillMaxSize().padding(24.dp),
-        verticalArrangement = Arrangement.Center,
-        horizontalAlignment = Alignment.CenterHorizontally,
-    ) {
-        Text(
-            text = stringResource(R.string.permission_denied_title),
-            style = MaterialTheme.typography.headlineMedium,
-        )
-        Spacer(Modifier.height(16.dp))
-        Text(
-            text = stringResource(R.string.permission_denied_body),
-            style = MaterialTheme.typography.bodyLarge,
-        )
-        Spacer(Modifier.height(32.dp))
-        Button(onClick = onRetry) {
-            Text(stringResource(R.string.permission_retry_button))
-        }
-        Spacer(Modifier.height(12.dp))
-        OutlinedButton(
+    PermissionScaffold(
+        modifier = modifier,
+        hero = { BrandHero(denied = true) },
+        actions = {
+            Button(
                 onClick = {
                     val intent = Intent(Settings.ACTION_APPLICATION_DETAILS_SETTINGS).apply {
                         data = Uri.fromParts("package", context.packageName, null)
@@ -123,8 +189,170 @@ private fun DeniedContent(
                     }
                     context.startActivity(intent)
                 },
+                modifier = Modifier.fillMaxWidth().height(56.dp),
             ) {
-            Text(stringResource(R.string.permission_open_settings_button))
+                Text(
+                    text = stringResource(R.string.permission_open_settings_button),
+                    style = MaterialTheme.typography.titleMedium,
+                )
+            }
+            TextButton(
+                onClick = onRetry,
+                modifier = Modifier.fillMaxWidth(),
+            ) {
+                Text(stringResource(R.string.permission_retry_button))
+            }
+        },
+    ) {
+        Text(
+            text = stringResource(R.string.permission_denied_title),
+            style = MaterialTheme.typography.headlineMedium,
+            textAlign = TextAlign.Center,
+        )
+        Spacer(Modifier.height(12.dp))
+        Text(
+            text = stringResource(R.string.permission_denied_body),
+            style = MaterialTheme.typography.bodyLarge,
+            color = MaterialTheme.colorScheme.onSurfaceVariant,
+            textAlign = TextAlign.Center,
+        )
+    }
+}
+
+/**
+ * Shared onboarding shell: a scrollable, centred hero + body with the call(s) to
+ * action pinned to the bottom (clear of the navigation bar). The content slot is
+ * centred horizontally; benefit rows fill the width so their own content
+ * left-aligns.
+ */
+@Composable
+private fun PermissionScaffold(
+    hero: @Composable () -> Unit,
+    actions: @Composable ColumnScope.() -> Unit,
+    modifier: Modifier = Modifier,
+    body: @Composable ColumnScope.() -> Unit,
+) {
+    Scaffold(
+        modifier = modifier,
+        containerColor = MaterialTheme.colorScheme.surface,
+        bottomBar = {
+            Column(
+                modifier = Modifier
+                    .fillMaxWidth()
+                    .navigationBarsPadding()
+                    .padding(horizontal = Space.md, vertical = Space.sm),
+                horizontalAlignment = Alignment.CenterHorizontally,
+                verticalArrangement = Arrangement.spacedBy(4.dp),
+                content = actions,
+            )
+        },
+    ) { innerPadding ->
+        Column(
+            modifier = Modifier
+                .fillMaxSize()
+                .padding(innerPadding)
+                .verticalScroll(rememberScrollState())
+                .padding(horizontal = Space.md),
+            horizontalAlignment = Alignment.CenterHorizontally,
+        ) {
+            Spacer(Modifier.height(Space.xl))
+            hero()
+            Spacer(Modifier.height(Space.lg))
+            body()
+            Spacer(Modifier.height(Space.md))
         }
     }
 }
+
+/** The app's adaptive launcher mark, reconstructed as a large branded squircle. */
+@Composable
+private fun BrandHero(denied: Boolean) {
+    Box(contentAlignment = Alignment.Center) {
+        Box(
+            modifier = Modifier
+                .size(128.dp)
+                .clip(RoundedCornerShape(34.dp))
+                .background(colorResource(R.color.ic_launcher_background)),
+        ) {
+            Image(
+                painter = painterResource(R.drawable.ic_launcher_foreground),
+                contentDescription = stringResource(R.string.app_name),
+                modifier = Modifier.fillMaxSize(),
+            )
+        }
+        if (denied) {
+            // A small lock badge sits over the corner to signal "blocked".
+            Box(
+                modifier = Modifier
+                    .align(Alignment.BottomEnd)
+                    .offset(x = 10.dp, y = 10.dp)
+                    .size(44.dp)
+                    .clip(CircleShape)
+                    .background(MaterialTheme.colorScheme.errorContainer),
+                contentAlignment = Alignment.Center,
+            ) {
+                Icon(
+                    imageVector = Icons.Filled.Lock,
+                    contentDescription = null,
+                    tint = MaterialTheme.colorScheme.onErrorContainer,
+                    modifier = Modifier.size(24.dp),
+                )
+            }
+        }
+    }
+}
+
+/** One trust point: a tonal icon chip on the left, title + supporting text right. */
+@Composable
+private fun BenefitRow(icon: ImageVector, title: String, body: String) {
+    Row(
+        modifier = Modifier.fillMaxWidth(),
+        verticalAlignment = Alignment.CenterVertically,
+    ) {
+        Box(
+            modifier = Modifier
+                .size(44.dp)
+                .clip(CircleShape)
+                .background(MaterialTheme.colorScheme.secondaryContainer),
+            contentAlignment = Alignment.Center,
+        ) {
+            Icon(
+                imageVector = icon,
+                contentDescription = null,
+                tint = MaterialTheme.colorScheme.onSecondaryContainer,
+                modifier = Modifier.size(22.dp),
+            )
+        }
+        Spacer(Modifier.width(Space.sm))
+        Column(modifier = Modifier.weight(1f)) {
+            Text(text = title, style = MaterialTheme.typography.titleMedium)
+            Text(
+                text = body,
+                style = MaterialTheme.typography.bodyMedium,
+                color = MaterialTheme.colorScheme.onSurfaceVariant,
+            )
+        }
+    }
+}
+
+@Composable
+private fun PrivacyFootnote() {
+    Row(
+        modifier = Modifier.fillMaxWidth().padding(top = 4.dp),
+        horizontalArrangement = Arrangement.Center,
+        verticalAlignment = Alignment.CenterVertically,
+    ) {
+        Icon(
+            imageVector = Icons.Filled.Lock,
+            contentDescription = null,
+            tint = MaterialTheme.colorScheme.onSurfaceVariant,
+            modifier = Modifier.size(14.dp),
+        )
+        Spacer(Modifier.width(6.dp))
+        Text(
+            text = stringResource(R.string.permission_privacy_footnote),
+            style = MaterialTheme.typography.labelMedium,
+            color = MaterialTheme.colorScheme.onSurfaceVariant,
+        )
+    }
+}

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

@@ -0,0 +1,36 @@
+package de.jeanlucmakiola.calendula.ui.settings
+
+import androidx.appcompat.app.AppCompatDelegate
+import androidx.core.os.LocaleListCompat
+
+/** UI-facing language choice. AUTO follows the system languages. */
+enum class LanguagePref { AUTO, GERMAN, ENGLISH }
+
+/**
+ * Per-app language via AppCompatDelegate. On API 33+ this delegates to the
+ * platform per-app-languages API; below that the appcompat backport persists
+ * the choice itself (manifest `autoStoreLocales` service), so we don't mirror
+ * it in DataStore. Setting a locale recreates the activity, which re-reads the
+ * current value for the dropdown.
+ */
+object AppLanguage {
+
+    fun current(): LanguagePref {
+        val locales = AppCompatDelegate.getApplicationLocales()
+        if (locales.isEmpty) return LanguagePref.AUTO
+        return when (locales[0]?.language) {
+            "de" -> LanguagePref.GERMAN
+            "en" -> LanguagePref.ENGLISH
+            else -> LanguagePref.AUTO
+        }
+    }
+
+    fun apply(pref: LanguagePref) {
+        val locales = when (pref) {
+            LanguagePref.AUTO -> LocaleListCompat.getEmptyLocaleList()
+            LanguagePref.GERMAN -> LocaleListCompat.forLanguageTags("de")
+            LanguagePref.ENGLISH -> LocaleListCompat.forLanguageTags("en")
+        }
+        AppCompatDelegate.setApplicationLocales(locales)
+    }
+}

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

@@ -0,0 +1,326 @@
+package de.jeanlucmakiola.calendula.ui.settings
+
+import android.content.Intent
+import androidx.activity.compose.BackHandler
+import androidx.core.net.toUri
+import androidx.compose.foundation.background
+import androidx.compose.foundation.clickable
+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.width
+import androidx.compose.foundation.rememberScrollState
+import androidx.compose.foundation.verticalScroll
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.automirrored.filled.ArrowBack
+import androidx.compose.material.icons.filled.ArrowDropDown
+import androidx.compose.material3.DropdownMenu
+import androidx.compose.material3.DropdownMenuItem
+import androidx.compose.material3.ExperimentalMaterial3Api
+import androidx.compose.material3.HorizontalDivider
+import androidx.compose.material3.Icon
+import androidx.compose.material3.IconButton
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Scaffold
+import androidx.compose.material3.Switch
+import androidx.compose.material3.Text
+import androidx.compose.material3.TextButton
+import androidx.compose.material3.TopAppBar
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.platform.LocalContext
+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.data.prefs.ThemeMode
+import de.jeanlucmakiola.calendula.data.prefs.WeekStartPref
+
+/**
+ * Settings (M4) — appearance (theme, dynamic colour, week start), language,
+ * and an about section. A full-screen destination; [onBack] pops it.
+ */
+@OptIn(ExperimentalMaterial3Api::class)
+@Composable
+fun SettingsScreen(
+    onBack: () -> Unit,
+    modifier: Modifier = Modifier,
+    viewModel: SettingsViewModel = hiltViewModel(),
+) {
+    val state by viewModel.state.collectAsStateWithLifecycle()
+
+    // Intercept the system back button/gesture — without this it falls through
+    // to the activity and closes the app instead of returning to the calendar.
+    BackHandler { onBack() }
+
+    Scaffold(
+        modifier = modifier
+            .fillMaxSize()
+            .background(MaterialTheme.colorScheme.surface),
+        topBar = {
+            TopAppBar(
+                title = { Text(stringResource(R.string.settings_title)) },
+                navigationIcon = {
+                    IconButton(onClick = onBack) {
+                        Icon(
+                            Icons.AutoMirrored.Filled.ArrowBack,
+                            contentDescription = stringResource(R.string.settings_back),
+                        )
+                    }
+                },
+            )
+        },
+    ) { innerPadding ->
+        Column(
+            modifier = Modifier
+                .padding(innerPadding)
+                .fillMaxSize()
+                .verticalScroll(rememberScrollState()),
+        ) {
+            SectionHeader(stringResource(R.string.settings_section_appearance))
+
+            SettingDropdownRow(
+                title = stringResource(R.string.settings_theme),
+                selected = state.themeMode,
+                options = ThemeMode.entries,
+                optionLabel = { themeLabel(it) },
+                onSelect = viewModel::setThemeMode,
+            )
+            DynamicColorRow(
+                checked = state.dynamicColor,
+                enabled = state.dynamicColorAvailable,
+                onCheckedChange = viewModel::setDynamicColor,
+            )
+            SettingDropdownRow(
+                title = stringResource(R.string.settings_week_start),
+                selected = state.weekStart,
+                options = WeekStartPref.entries,
+                optionLabel = { weekStartLabel(it) },
+                onSelect = viewModel::setWeekStart,
+            )
+
+            HorizontalDivider(Modifier.padding(vertical = 8.dp))
+            SectionHeader(stringResource(R.string.settings_section_language))
+            LanguageRow()
+
+            HorizontalDivider(Modifier.padding(vertical = 8.dp))
+            SectionHeader(stringResource(R.string.settings_section_about))
+            AboutSection()
+            Spacer(Modifier.height(24.dp))
+        }
+    }
+}
+
+@Composable
+private fun LanguageRow() {
+    // Setting a locale recreates the activity; mirror the choice locally so the
+    // dropdown updates instantly even before the recreation lands.
+    var current by remember { mutableStateOf(AppLanguage.current()) }
+    SettingDropdownRow(
+        title = stringResource(R.string.settings_language),
+        selected = current,
+        options = LanguagePref.entries,
+        optionLabel = { languageLabel(it) },
+        onSelect = {
+            current = it
+            AppLanguage.apply(it)
+        },
+    )
+}
+
+@Composable
+private fun SectionHeader(text: String) {
+    Text(
+        text = text,
+        style = MaterialTheme.typography.labelLarge,
+        color = MaterialTheme.colorScheme.primary,
+        modifier = Modifier.padding(start = 24.dp, end = 24.dp, top = 16.dp, bottom = 4.dp),
+    )
+}
+
+@Composable
+private fun <T> SettingDropdownRow(
+    title: String,
+    selected: T,
+    options: List<T>,
+    optionLabel: @Composable (T) -> String,
+    onSelect: (T) -> Unit,
+) {
+    var expanded by remember { mutableStateOf(false) }
+    Box {
+        Row(
+            modifier = Modifier
+                .fillMaxWidth()
+                .clickable { expanded = true }
+                .padding(horizontal = 24.dp, vertical = 16.dp),
+            verticalAlignment = Alignment.CenterVertically,
+        ) {
+            Text(
+                text = title,
+                style = MaterialTheme.typography.bodyLarge,
+                modifier = Modifier.weight(1f),
+            )
+            Text(
+                text = optionLabel(selected),
+                style = MaterialTheme.typography.bodyMedium,
+                color = MaterialTheme.colorScheme.onSurfaceVariant,
+            )
+            Icon(
+                Icons.Default.ArrowDropDown,
+                contentDescription = null,
+                tint = MaterialTheme.colorScheme.onSurfaceVariant,
+            )
+        }
+        DropdownMenu(expanded = expanded, onDismissRequest = { expanded = false }) {
+            options.forEach { option ->
+                DropdownMenuItem(
+                    text = { Text(optionLabel(option)) },
+                    onClick = {
+                        expanded = false
+                        onSelect(option)
+                    },
+                )
+            }
+        }
+    }
+}
+
+@Composable
+private fun DynamicColorRow(
+    checked: Boolean,
+    enabled: Boolean,
+    onCheckedChange: (Boolean) -> Unit,
+) {
+    Row(
+        modifier = Modifier
+            .fillMaxWidth()
+            .padding(horizontal = 24.dp, vertical = 12.dp),
+        verticalAlignment = Alignment.CenterVertically,
+    ) {
+        Column(Modifier.weight(1f)) {
+            Text(
+                text = stringResource(R.string.settings_dynamic_color),
+                style = MaterialTheme.typography.bodyLarge,
+                color = if (enabled) MaterialTheme.colorScheme.onSurface
+                else MaterialTheme.colorScheme.onSurfaceVariant,
+            )
+            if (!enabled) {
+                Text(
+                    text = stringResource(R.string.settings_dynamic_color_unavailable),
+                    style = MaterialTheme.typography.bodySmall,
+                    color = MaterialTheme.colorScheme.onSurfaceVariant,
+                )
+            }
+        }
+        Switch(
+            checked = checked,
+            onCheckedChange = onCheckedChange,
+            enabled = enabled,
+        )
+    }
+}
+
+@Composable
+private fun AboutSection() {
+    val context = LocalContext.current
+    val versionName = remember {
+        runCatching {
+            context.packageManager.getPackageInfo(context.packageName, 0).versionName
+        }.getOrNull() ?: "—"
+    }
+    val sourceUrl = stringResource(R.string.about_source_url)
+
+    AboutRow(
+        title = stringResource(R.string.settings_version),
+        value = versionName,
+    )
+    AboutRow(
+        title = stringResource(R.string.settings_license),
+        value = stringResource(R.string.settings_license_value),
+    )
+    Row(
+        modifier = Modifier
+            .fillMaxWidth()
+            .padding(horizontal = 16.dp, vertical = 4.dp),
+        verticalAlignment = Alignment.CenterVertically,
+    ) {
+        Column(Modifier.weight(1f).padding(start = 8.dp)) {
+            Text(
+                text = stringResource(R.string.settings_source),
+                style = MaterialTheme.typography.bodyLarge,
+            )
+            Text(
+                text = sourceUrl.removePrefix("https://"),
+                style = MaterialTheme.typography.bodySmall,
+                color = MaterialTheme.colorScheme.onSurfaceVariant,
+            )
+        }
+        TextButton(onClick = {
+            val intent = Intent(Intent.ACTION_VIEW, sourceUrl.toUri())
+            runCatching { context.startActivity(intent) }
+        }) {
+            Text(stringResource(R.string.settings_source_open))
+        }
+    }
+}
+
+@Composable
+private fun AboutRow(title: String, value: String) {
+    Row(
+        modifier = Modifier
+            .fillMaxWidth()
+            .padding(horizontal = 24.dp, vertical = 12.dp),
+        verticalAlignment = Alignment.CenterVertically,
+    ) {
+        Text(
+            text = title,
+            style = MaterialTheme.typography.bodyLarge,
+            modifier = Modifier.weight(1f),
+        )
+        Text(
+            text = value,
+            style = MaterialTheme.typography.bodyMedium,
+            color = MaterialTheme.colorScheme.onSurfaceVariant,
+        )
+        Spacer(Modifier.width(8.dp))
+    }
+}
+
+@Composable
+private fun themeLabel(mode: ThemeMode): String = stringResource(
+    when (mode) {
+        ThemeMode.SYSTEM -> R.string.settings_theme_system
+        ThemeMode.LIGHT -> R.string.settings_theme_light
+        ThemeMode.DARK -> R.string.settings_theme_dark
+    },
+)
+
+@Composable
+private fun weekStartLabel(pref: WeekStartPref): String = stringResource(
+    when (pref) {
+        WeekStartPref.AUTO -> R.string.settings_week_start_auto
+        WeekStartPref.MONDAY -> R.string.settings_week_start_monday
+        WeekStartPref.SUNDAY -> R.string.settings_week_start_sunday
+    },
+)
+
+@Composable
+private fun languageLabel(pref: LanguagePref): String = stringResource(
+    when (pref) {
+        LanguagePref.AUTO -> R.string.settings_language_auto
+        LanguagePref.GERMAN -> R.string.settings_language_german
+        LanguagePref.ENGLISH -> R.string.settings_language_english
+    },
+)

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

@@ -0,0 +1,17 @@
+package de.jeanlucmakiola.calendula.ui.settings
+
+import de.jeanlucmakiola.calendula.data.prefs.ThemeMode
+import de.jeanlucmakiola.calendula.data.prefs.WeekStartPref
+
+/**
+ * Settings screen state (M4). Persisted preferences are instant to read, so
+ * there is no Loading/Failure here — only a populated Success snapshot.
+ * [dynamicColorAvailable] is false below Android 12, where the toggle is shown
+ * disabled.
+ */
+data class SettingsUiState(
+    val themeMode: ThemeMode = ThemeMode.SYSTEM,
+    val dynamicColor: Boolean = true,
+    val dynamicColorAvailable: Boolean = true,
+    val weekStart: WeekStartPref = WeekStartPref.AUTO,
+)

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

@@ -0,0 +1,53 @@
+package de.jeanlucmakiola.calendula.ui.settings
+
+import android.os.Build
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewModelScope
+import dagger.hilt.android.lifecycle.HiltViewModel
+import de.jeanlucmakiola.calendula.data.prefs.SettingsPrefs
+import de.jeanlucmakiola.calendula.data.prefs.ThemeMode
+import de.jeanlucmakiola.calendula.data.prefs.WeekStartPref
+import kotlinx.coroutines.flow.SharingStarted
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.combine
+import kotlinx.coroutines.flow.stateIn
+import kotlinx.coroutines.launch
+import javax.inject.Inject
+
+@HiltViewModel
+class SettingsViewModel @Inject constructor(
+    private val prefs: SettingsPrefs,
+) : ViewModel() {
+
+    private val dynamicColorAvailable = Build.VERSION.SDK_INT >= Build.VERSION_CODES.S
+
+    val state: StateFlow<SettingsUiState> =
+        combine(
+            prefs.themeMode,
+            prefs.dynamicColor,
+            prefs.weekStart,
+        ) { theme, dynamic, weekStart ->
+            SettingsUiState(
+                themeMode = theme,
+                dynamicColor = dynamic && dynamicColorAvailable,
+                dynamicColorAvailable = dynamicColorAvailable,
+                weekStart = weekStart,
+            )
+        }.stateIn(
+            scope = viewModelScope,
+            started = SharingStarted.WhileSubscribed(5_000L),
+            initialValue = SettingsUiState(dynamicColorAvailable = dynamicColorAvailable),
+        )
+
+    fun setThemeMode(mode: ThemeMode) {
+        viewModelScope.launch { prefs.setThemeMode(mode) }
+    }
+
+    fun setDynamicColor(enabled: Boolean) {
+        viewModelScope.launch { prefs.setDynamicColor(enabled) }
+    }
+
+    fun setWeekStart(pref: WeekStartPref) {
+        viewModelScope.launch { prefs.setWeekStart(pref) }
+    }
+}

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

@@ -7,6 +7,7 @@ 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
@@ -86,7 +87,6 @@ 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
@@ -111,6 +111,8 @@ private fun WeekUiState.Success.allDayStripHeight(): Dp {
 fun WeekScreen(
     selectedView: CalendarView,
     onSelectView: (CalendarView) -> Unit,
+    onEventClick: (EventInstance) -> Unit,
+    onOpenSettings: () -> Unit,
     modifier: Modifier = Modifier,
     viewModel: WeekViewModel = hiltViewModel(),
 ) {
@@ -133,7 +135,10 @@ fun WeekScreen(
     )
 
     val isOnCurrentWeek = when (val s = state) {
-        is WeekUiState.Success -> s.weekStart == s.today.startOfWeek(DayOfWeek.MONDAY)
+        // True when today falls inside the displayed week — independent of which
+        // weekday the user picked as the first day.
+        is WeekUiState.Success ->
+            s.today >= s.weekStart && s.today <= s.weekStart.plus(6, kotlinx.datetime.DateTimeUnit.DAY)
         else -> true
     }
 
@@ -150,9 +155,10 @@ fun WeekScreen(
         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 */ },
+                onSettings = {
+                    onOpenSettings()
+                    scope.launch { drawerState.close() }
+                },
             )
         },
     ) {
@@ -188,6 +194,7 @@ fun WeekScreen(
                 onSwipeNext = goNext,
                 onSwipePrev = goPrev,
                 onRetry = jumpToToday,
+                onEventClick = onEventClick,
                 modifier = Modifier
                     .padding(innerPadding)
                     .fillMaxSize(),
@@ -204,6 +211,7 @@ private fun WeekContent(
     onSwipeNext: () -> Unit,
     onSwipePrev: () -> Unit,
     onRetry: () -> Unit,
+    onEventClick: (EventInstance) -> Unit,
     modifier: Modifier = Modifier,
 ) {
     val density = LocalDensity.current
@@ -274,6 +282,7 @@ private fun WeekContent(
                 topSectionColor = topSectionColor,
                 scrollState = scrollState,
                 allDayHeight = allDayHeight,
+                onEventClick = onEventClick,
             )
         }
     }
@@ -285,6 +294,7 @@ private fun WeekSuccess(
     topSectionColor: Color,
     scrollState: ScrollState,
     allDayHeight: Dp,
+    onEventClick: (EventInstance) -> Unit,
 ) {
     Column(modifier = Modifier.fillMaxSize()) {
         Column(
@@ -293,12 +303,12 @@ private fun WeekSuccess(
                 .background(topSectionColor),
         ) {
             WeekDayHeader(days = state.days, today = state.today)
-            AllDayStrip(state = state, height = allDayHeight)
+            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)
+        Timeline(state = state, scrollState = scrollState, onEventClick = onEventClick)
     }
 }
 
@@ -433,7 +443,11 @@ private fun WeekNumberBadge(weekNumber: Int, modifier: Modifier = Modifier) {
 }
 
 @Composable
-private fun AllDayStrip(state: WeekUiState.Success, height: Dp) {
+private fun AllDayStrip(
+    state: WeekUiState.Success,
+    height: Dp,
+    onEventClick: (EventInstance) -> Unit,
+) {
     val dark = isSystemInDarkTheme()
 
     Row(
@@ -461,6 +475,7 @@ private fun AllDayStrip(state: WeekUiState.Success, height: Dp) {
                 AllDayBar(
                     event = span.event,
                     dark = dark,
+                    onClick = { onEventClick(span.event) },
                     modifier = Modifier
                         .offset(
                             x = colWidth * span.startCol,
@@ -476,11 +491,17 @@ private fun AllDayStrip(state: WeekUiState.Success, height: Dp) {
 }
 
 @Composable
-private fun AllDayBar(event: EventInstance, dark: Boolean, modifier: Modifier = Modifier) {
+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,
@@ -496,7 +517,11 @@ private fun AllDayBar(event: EventInstance, dark: Boolean, modifier: Modifier =
 }
 
 @Composable
-private fun Timeline(state: WeekUiState.Success, scrollState: ScrollState) {
+private fun Timeline(
+    state: WeekUiState.Success,
+    scrollState: ScrollState,
+    onEventClick: (EventInstance) -> Unit,
+) {
     val totalHeight = HOUR_HEIGHT * 24
     val dark = isSystemInDarkTheme()
 
@@ -551,6 +576,7 @@ private fun Timeline(state: WeekUiState.Success, scrollState: ScrollState) {
                         DayColumnCard(
                             blocks = state.timedByDay[day].orEmpty(),
                             dark = dark,
+                            onEventClick = onEventClick,
                             modifier = Modifier
                                 .weight(1f)
                                 .fillMaxHeight(),
@@ -566,6 +592,7 @@ private fun Timeline(state: WeekUiState.Success, scrollState: ScrollState) {
 private fun DayColumnCard(
     blocks: List<TimedBlock>,
     dark: Boolean,
+    onEventClick: (EventInstance) -> Unit,
     modifier: Modifier = Modifier,
 ) {
     Card(
@@ -587,6 +614,7 @@ private fun DayColumnCard(
                 EventBlock(
                     block = block,
                     dark = dark,
+                    onClick = { onEventClick(block.event) },
                     modifier = Modifier
                         .offset(x = laneWidth * block.lane, y = top)
                         .width(laneWidth)
@@ -602,6 +630,7 @@ private fun DayColumnCard(
 private fun EventBlock(
     block: TimedBlock,
     dark: Boolean,
+    onClick: () -> Unit,
     modifier: Modifier = Modifier,
 ) {
     val title = block.event.title.ifBlank { stringResource(R.string.event_untitled) }
@@ -610,6 +639,7 @@ private fun EventBlock(
     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" },
     ) {

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

@@ -5,6 +5,8 @@ import androidx.lifecycle.viewModelScope
 import dagger.hilt.android.lifecycle.HiltViewModel
 import de.jeanlucmakiola.calendula.data.calendar.CalendarRepository
 import de.jeanlucmakiola.calendula.data.di.IoDispatcher
+import de.jeanlucmakiola.calendula.data.prefs.SettingsPrefs
+import de.jeanlucmakiola.calendula.data.prefs.resolveFirstDay
 import de.jeanlucmakiola.calendula.domain.CalendarSource
 import de.jeanlucmakiola.calendula.domain.EventInstance
 import de.jeanlucmakiola.calendula.domain.FailureReason
@@ -15,8 +17,10 @@ import kotlinx.coroutines.flow.SharingStarted
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.catch
 import kotlinx.coroutines.flow.combine
+import kotlinx.coroutines.flow.distinctUntilChanged
 import kotlinx.coroutines.flow.flatMapLatest
 import kotlinx.coroutines.flow.flowOn
+import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.flow.stateIn
 import kotlinx.datetime.DateTimeUnit
 import kotlinx.datetime.DayOfWeek
@@ -28,6 +32,7 @@ import kotlinx.datetime.minus
 import kotlinx.datetime.plus
 import kotlinx.datetime.toInstant
 import kotlinx.datetime.toLocalDateTime
+import java.util.Locale
 import kotlin.time.Clock
 import kotlin.time.Instant
 import javax.inject.Inject
@@ -38,21 +43,41 @@ const val MINUTES_PER_DAY: Int = 24 * 60
 @HiltViewModel
 class WeekViewModel @Inject constructor(
     private val repository: CalendarRepository,
+    settingsPrefs: SettingsPrefs,
     @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 locale: Locale = Locale.getDefault()
 
     private val todayDate: LocalDate
         get() = Clock.System.now().toLocalDateTime(zone).date
 
-    private val _weekStartDate = MutableStateFlow(todayDate.startOfWeek(weekStart))
-    val weekStartDate: StateFlow<LocalDate> = _weekStartDate
+    /** First day of the week, from the Settings preference (AUTO → locale). */
+    private val weekStart: StateFlow<DayOfWeek> = settingsPrefs.weekStart
+        .map { it.resolveFirstDay(locale) }
+        .stateIn(
+            scope = viewModelScope,
+            started = SharingStarted.WhileSubscribed(5_000L),
+            initialValue = DayOfWeek.MONDAY,
+        )
 
-    val state: StateFlow<WeekUiState> = _weekStartDate
+    // Anchor is a representative day inside the visible week; the actual week
+    // start is derived against [weekStart], so changing the first-day preference
+    // re-frames the same week instead of jumping.
+    private val _anchor = MutableStateFlow(todayDate)
+
+    val weekStartDate: StateFlow<LocalDate> =
+        combine(_anchor, weekStart) { anchor, ws -> anchor.startOfWeek(ws) }
+            .stateIn(
+                scope = viewModelScope,
+                started = SharingStarted.WhileSubscribed(5_000L),
+                initialValue = todayDate.startOfWeek(DayOfWeek.MONDAY),
+            )
+
+    val state: StateFlow<WeekUiState> =
+        combine(_anchor, weekStart) { anchor, ws -> anchor.startOfWeek(ws) }
+            .distinctUntilChanged()
             .flatMapLatest { start ->
                 val range = weekRange(start, zone)
                 combine(
@@ -71,15 +96,15 @@ class WeekViewModel @Inject constructor(
             )
 
     fun goToPrev() {
-        _weekStartDate.value = _weekStartDate.value.minus(7, DateTimeUnit.DAY)
+        _anchor.value = _anchor.value.minus(7, DateTimeUnit.DAY)
     }
 
     fun goToNext() {
-        _weekStartDate.value = _weekStartDate.value.plus(7, DateTimeUnit.DAY)
+        _anchor.value = _anchor.value.plus(7, DateTimeUnit.DAY)
     }
 
     fun goToToday() {
-        _weekStartDate.value = todayDate.startOfWeek(weekStart)
+        _anchor.value = todayDate
     }
 
     private fun buildState(

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

@@ -12,13 +12,20 @@
     <string name="state_failure_provider">Kalender konnte nicht gelesen werden.</string>
 
     <!-- Permission-Flow (F1) -->
-    <string name="permission_rationale_title">Kalender-Zugriff</string>
-    <string name="permission_rationale_body">Calendula liest nur deinen Gerätekalender — keine Daten verlassen das Gerät.</string>
-    <string name="permission_request_button">Weiter</string>
+    <string name="permission_rationale_title">Alle Termine, schön im Blick</string>
+    <string name="permission_rationale_body">Calendula braucht Lesezugriff auf deinen Kalender, um deine Termine zu zeigen. Mehr verlangt die App nie.</string>
+    <string name="permission_request_button">Kalender-Zugriff erlauben</string>
     <string name="permission_denied_title">Kalender-Zugriff abgelehnt</string>
     <string name="permission_denied_body">Ohne Kalender-Zugriff kann Calendula keine Termine anzeigen. Du kannst den Zugriff in den System-Einstellungen wieder erlauben.</string>
     <string name="permission_open_settings_button">System-Einstellungen öffnen</string>
     <string name="permission_retry_button">Erneut versuchen</string>
+    <string name="permission_benefit_private_title">Bleibt auf deinem Gerät</string>
+    <string name="permission_benefit_private_body">Deine Kalender werden lokal gelesen und verlassen das Telefon nie.</string>
+    <string name="permission_benefit_sync_title">Alle Kalender vereint</string>
+    <string name="permission_benefit_sync_body">Google, CalDAV, lokal — alles, was synchronisiert ist, erscheint automatisch.</string>
+    <string name="permission_benefit_privacy_title">Kein Tracking, niemals</string>
+    <string name="permission_benefit_privacy_body">Keine Telemetrie, keine Analyse, keine Werbung.</string>
+    <string name="permission_privacy_footnote">Nur Lesezugriff · keine Internet-Berechtigung</string>
 
     <!-- Monatsansicht (S1) -->
     <string name="month_prev">Vorheriger Monat</string>
@@ -26,8 +33,6 @@
     <string name="month_today_action">Heute</string>
     <string name="month_more_actions">Weitere Aktionen</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>
 
@@ -38,6 +43,67 @@
     <!-- 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>
+
+    <!-- Event-Detail — vollständiges Auslesen (v0.6) -->
+    <string name="event_detail_reminders">Erinnerungen</string>
+    <string name="event_detail_timezone">Zeitzone</string>
+    <string name="event_status_tentative">Vorläufig</string>
+    <string name="event_status_cancelled">Abgesagt</string>
+    <string name="event_availability_free">Frei</string>
+    <string name="event_access_private">Privat</string>
+    <string name="event_access_confidential">Vertraulich</string>
+    <string name="event_attendee_organizer">Organisator</string>
+    <string name="event_attendee_optional">Optional</string>
+    <string name="event_attendee_resource">Ressource</string>
+    <string name="event_detail_self_response">Deine Antwort: %1$s</string>
+    <string name="reminder_at_time">Zur Startzeit</string>
+    <string name="reminder_default">Standarderinnerung</string>
+    <plurals name="reminder_minutes">
+        <item quantity="one">%d Minute vorher</item>
+        <item quantity="other">%d Minuten vorher</item>
+    </plurals>
+    <plurals name="reminder_hours">
+        <item quantity="one">%d Stunde vorher</item>
+        <item quantity="other">%d Stunden vorher</item>
+    </plurals>
+    <plurals name="reminder_days">
+        <item quantity="one">%d Tag vorher</item>
+        <item quantity="other">%d Tage vorher</item>
+    </plurals>
+    <plurals name="reminder_weeks">
+        <item quantity="one">%d Woche vorher</item>
+        <item quantity="other">%d Wochen vorher</item>
+    </plurals>
+
     <!-- Geteilte Event-Strings -->
     <string name="event_untitled">(Ohne Titel)</string>
 
@@ -45,4 +111,33 @@
     <string name="view_month">Monat</string>
     <string name="view_week">Woche</string>
     <string name="view_day">Tag</string>
+
+    <!-- Kalender-Filter (M3) -->
+    <string name="filter_title">Kalender</string>
+
+    <!-- Einstellungen (M4) -->
+    <string name="settings_title">Einstellungen</string>
+    <string name="settings_back">Zurück</string>
+    <string name="settings_section_appearance">Darstellung</string>
+    <string name="settings_theme">Design</string>
+    <string name="settings_theme_system">System</string>
+    <string name="settings_theme_light">Hell</string>
+    <string name="settings_theme_dark">Dunkel</string>
+    <string name="settings_dynamic_color">Dynamische Farben</string>
+    <string name="settings_dynamic_color_unavailable">Erfordert Android 12 oder neuer</string>
+    <string name="settings_week_start">Wochenstart</string>
+    <string name="settings_week_start_auto">Automatisch</string>
+    <string name="settings_week_start_monday">Montag</string>
+    <string name="settings_week_start_sunday">Sonntag</string>
+    <string name="settings_section_language">Sprache</string>
+    <string name="settings_language">App-Sprache</string>
+    <string name="settings_language_auto">Systemstandard</string>
+    <string name="settings_language_german">Deutsch</string>
+    <string name="settings_language_english">English</string>
+    <string name="settings_section_about">Über</string>
+    <string name="settings_version">Version</string>
+    <string name="settings_license">Lizenz</string>
+    <string name="settings_license_value">MIT</string>
+    <string name="settings_source">Quellcode</string>
+    <string name="settings_source_open">Öffnen</string>
 </resources>

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

@@ -13,13 +13,20 @@
     <string name="state_failure_provider">Could not read the calendar.</string>
 
     <!-- Permission flow (F1) -->
-    <string name="permission_rationale_title">Calendar access</string>
-    <string name="permission_rationale_body">Calendula reads only your device calendar — no data leaves your device.</string>
-    <string name="permission_request_button">Continue</string>
+    <string name="permission_rationale_title">See all your events, beautifully</string>
+    <string name="permission_rationale_body">Calendula needs to read your calendar to show your events. That\'s the only thing it ever asks for.</string>
+    <string name="permission_request_button">Grant calendar access</string>
     <string name="permission_denied_title">Calendar access denied</string>
     <string name="permission_denied_body">Calendula cannot show events without calendar access. You can grant it again in the system settings.</string>
     <string name="permission_open_settings_button">Open system settings</string>
     <string name="permission_retry_button">Try again</string>
+    <string name="permission_benefit_private_title">Stays on your device</string>
+    <string name="permission_benefit_private_body">Your calendars are read locally and never leave the phone.</string>
+    <string name="permission_benefit_sync_title">All your calendars, together</string>
+    <string name="permission_benefit_sync_body">Google, CalDAV, local — anything synced to the device just appears.</string>
+    <string name="permission_benefit_privacy_title">No tracking, ever</string>
+    <string name="permission_benefit_privacy_body">Zero telemetry, zero analytics, no ads.</string>
+    <string name="permission_privacy_footnote">Read-only · no internet permission</string>
 
     <!-- Month view (S1) -->
     <string name="month_prev">Previous month</string>
@@ -27,8 +34,6 @@
     <string name="month_today_action">Today</string>
     <string name="month_more_actions">More actions</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>
 
@@ -39,6 +44,67 @@
     <!-- 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>
+
+    <!-- Event detail — full read (v0.6) -->
+    <string name="event_detail_reminders">Reminders</string>
+    <string name="event_detail_timezone">Time zone</string>
+    <string name="event_status_tentative">Tentative</string>
+    <string name="event_status_cancelled">Cancelled</string>
+    <string name="event_availability_free">Free</string>
+    <string name="event_access_private">Private</string>
+    <string name="event_access_confidential">Confidential</string>
+    <string name="event_attendee_organizer">Organizer</string>
+    <string name="event_attendee_optional">Optional</string>
+    <string name="event_attendee_resource">Resource</string>
+    <string name="event_detail_self_response">Your response: %1$s</string>
+    <string name="reminder_at_time">At time of event</string>
+    <string name="reminder_default">Default reminder</string>
+    <plurals name="reminder_minutes">
+        <item quantity="one">%d minute before</item>
+        <item quantity="other">%d minutes before</item>
+    </plurals>
+    <plurals name="reminder_hours">
+        <item quantity="one">%d hour before</item>
+        <item quantity="other">%d hours before</item>
+    </plurals>
+    <plurals name="reminder_days">
+        <item quantity="one">%d day before</item>
+        <item quantity="other">%d days before</item>
+    </plurals>
+    <plurals name="reminder_weeks">
+        <item quantity="one">%d week before</item>
+        <item quantity="other">%d weeks before</item>
+    </plurals>
+
     <!-- Shared event strings -->
     <string name="event_untitled">(No title)</string>
 
@@ -46,4 +112,34 @@
     <string name="view_month">Month</string>
     <string name="view_week">Week</string>
     <string name="view_day">Day</string>
+
+    <!-- Calendar filter (M3) -->
+    <string name="filter_title">Calendars</string>
+
+    <!-- Settings (M4) -->
+    <string name="settings_title">Settings</string>
+    <string name="settings_back">Back</string>
+    <string name="settings_section_appearance">Appearance</string>
+    <string name="settings_theme">Theme</string>
+    <string name="settings_theme_system">System</string>
+    <string name="settings_theme_light">Light</string>
+    <string name="settings_theme_dark">Dark</string>
+    <string name="settings_dynamic_color">Dynamic colour</string>
+    <string name="settings_dynamic_color_unavailable">Requires Android 12 or newer</string>
+    <string name="settings_week_start">Week starts on</string>
+    <string name="settings_week_start_auto">Automatic</string>
+    <string name="settings_week_start_monday">Monday</string>
+    <string name="settings_week_start_sunday">Sunday</string>
+    <string name="settings_section_language">Language</string>
+    <string name="settings_language">App language</string>
+    <string name="settings_language_auto">System default</string>
+    <string name="settings_language_german">Deutsch</string>
+    <string name="settings_language_english">English</string>
+    <string name="settings_section_about">About</string>
+    <string name="settings_version">Version</string>
+    <string name="settings_license">License</string>
+    <string name="settings_license_value">MIT</string>
+    <string name="settings_source">Source code</string>
+    <string name="settings_source_open">Open</string>
+    <string name="about_source_url" translatable="false">https://gitea.jeanlucmakiola.de/makiolaj/calendula</string>
 </resources>

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

@@ -1,7 +1,11 @@
 package de.jeanlucmakiola.calendula.data.calendar
 
+import androidx.datastore.core.DataStore
+import androidx.datastore.preferences.core.PreferenceDataStoreFactory
+import androidx.datastore.preferences.core.Preferences
 import app.cash.turbine.test
 import com.google.common.truth.Truth.assertThat
+import de.jeanlucmakiola.calendula.data.prefs.CalendarPrefs
 import de.jeanlucmakiola.calendula.domain.CalendarSource
 import de.jeanlucmakiola.calendula.domain.EventInstance
 import kotlinx.coroutines.Dispatchers
@@ -10,15 +14,29 @@ import kotlinx.coroutines.test.UnconfinedTestDispatcher
 import kotlinx.coroutines.test.runTest
 import kotlin.time.Instant
 import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.io.TempDir
+import java.nio.file.Path
 
 @OptIn(ExperimentalCoroutinesApi::class)
 class CalendarRepositoryImplTest {
 
+    private fun newPrefs(tempDir: Path): CalendarPrefs =
+        CalendarPrefs(newDataStore(tempDir))
+
+    private fun newDataStore(tempDir: Path): DataStore<Preferences> =
+        PreferenceDataStoreFactory.create(
+            produceFile = { tempDir.resolve("repo_test_prefs.preferences_pb").toFile() },
+        )
+
     private fun makeCal(id: Long, name: String = "Cal $id"): CalendarSource =
         CalendarSource(id, name, "x@y", "LOCAL", 0xFF112233.toInt(), true)
 
-    private fun makeEvent(id: Long, title: String = "E $id"): EventInstance = EventInstance(
-        instanceId = id, eventId = id, calendarId = 1L,
+    private fun makeEvent(
+        id: Long,
+        title: String = "E $id",
+        calendarId: Long = 1L,
+    ): EventInstance = EventInstance(
+        instanceId = id, eventId = id, calendarId = calendarId,
         title = title,
         start = Instant.fromEpochMilliseconds(1_000_000_000L),
         end = Instant.fromEpochMilliseconds(1_000_003_600L),
@@ -26,11 +44,11 @@ class CalendarRepositoryImplTest {
     )
 
     @Test
-    fun `calendars emits initial query result on subscribe`() = runTest {
+    fun `calendars emits initial query result on subscribe`(@TempDir tempDir: Path) = runTest {
         val fake = FakeCalendarDataSource().apply {
             calendarsResult = listOf(makeCal(1L), makeCal(2L))
         }
-        val repo = CalendarRepositoryImpl(fake, UnconfinedTestDispatcher(testScheduler))
+        val repo = CalendarRepositoryImpl(fake, newPrefs(tempDir), UnconfinedTestDispatcher(testScheduler))
 
         repo.calendars().test {
             val first = awaitItem()
@@ -40,11 +58,11 @@ class CalendarRepositoryImplTest {
     }
 
     @Test
-    fun `calendars re-emits after change listener tick`() = runTest {
+    fun `calendars re-emits after change listener tick`(@TempDir tempDir: Path) = runTest {
         val fake = FakeCalendarDataSource().apply {
             calendarsResult = listOf(makeCal(1L))
         }
-        val repo = CalendarRepositoryImpl(fake, UnconfinedTestDispatcher(testScheduler))
+        val repo = CalendarRepositoryImpl(fake, newPrefs(tempDir), UnconfinedTestDispatcher(testScheduler))
 
         repo.calendars().test {
             assertThat(awaitItem().map { it.id }).containsExactly(1L)
@@ -58,7 +76,7 @@ class CalendarRepositoryImplTest {
     }
 
     @Test
-    fun `instances forwards epoch-millis bounds to data source`() = runTest {
+    fun `instances forwards epoch-millis bounds to data source`(@TempDir tempDir: Path) = runTest {
         var observedBegin: Long? = null
         var observedEnd: Long? = null
         val fake = FakeCalendarDataSource().apply {
@@ -68,7 +86,7 @@ class CalendarRepositoryImplTest {
                 listOf(makeEvent(10L))
             }
         }
-        val repo = CalendarRepositoryImpl(fake, UnconfinedTestDispatcher(testScheduler))
+        val repo = CalendarRepositoryImpl(fake, newPrefs(tempDir), UnconfinedTestDispatcher(testScheduler))
 
         val range = Instant.fromEpochMilliseconds(1_000L)..Instant.fromEpochMilliseconds(2_000L)
         repo.instances(range).test {
@@ -80,11 +98,11 @@ class CalendarRepositoryImplTest {
     }
 
     @Test
-    fun `instances passes-through whatever the data source returns`() = runTest {
+    fun `instances passes-through whatever the data source returns`(@TempDir tempDir: Path) = runTest {
         val fake = FakeCalendarDataSource().apply {
             instancesResult = {_, _ -> listOf(makeEvent(10L, "Good")) }
         }
-        val repo = CalendarRepositoryImpl(fake, UnconfinedTestDispatcher(testScheduler))
+        val repo = CalendarRepositoryImpl(fake, newPrefs(tempDir), UnconfinedTestDispatcher(testScheduler))
 
         val range = Instant.fromEpochMilliseconds(0)..Instant.fromEpochMilliseconds(10_000L)
         repo.instances(range).test {
@@ -95,11 +113,56 @@ class CalendarRepositoryImplTest {
     }
 
     @Test
-    fun `eventDetail throws NoSuchEventException when data source returns null`() = runTest {
+    fun `instances drops events whose calendar the user hid`(@TempDir tempDir: Path) = runTest {
+        val prefs = newPrefs(tempDir)
+        prefs.setHiddenCalendarIds(setOf(2L))
+        val fake = FakeCalendarDataSource().apply {
+            instancesResult = { _, _ ->
+                listOf(
+                    makeEvent(10L, "Visible", calendarId = 1L),
+                    makeEvent(11L, "Hidden", calendarId = 2L),
+                )
+            }
+        }
+        val repo = CalendarRepositoryImpl(fake, prefs, UnconfinedTestDispatcher(testScheduler))
+
+        val range = Instant.fromEpochMilliseconds(0)..Instant.fromEpochMilliseconds(10_000L)
+        repo.instances(range).test {
+            assertThat(awaitItem().map { it.title }).containsExactly("Visible")
+            cancelAndIgnoreRemainingEvents()
+        }
+    }
+
+    @Test
+    fun `instances re-emits when the hidden set changes`(@TempDir tempDir: Path) = runTest {
+        val prefs = newPrefs(tempDir)
+        val fake = FakeCalendarDataSource().apply {
+            instancesResult = { _, _ ->
+                listOf(
+                    makeEvent(10L, "A", calendarId = 1L),
+                    makeEvent(11L, "B", calendarId = 2L),
+                )
+            }
+        }
+        val repo = CalendarRepositoryImpl(fake, prefs, UnconfinedTestDispatcher(testScheduler))
+
+        val range = Instant.fromEpochMilliseconds(0)..Instant.fromEpochMilliseconds(10_000L)
+        repo.instances(range).test {
+            assertThat(awaitItem().map { it.title }).containsExactly("A", "B").inOrder()
+
+            prefs.setHiddenCalendarIds(setOf(2L))
+
+            assertThat(awaitItem().map { it.title }).containsExactly("A")
+            cancelAndIgnoreRemainingEvents()
+        }
+    }
+
+    @Test
+    fun `eventDetail throws NoSuchEventException when data source returns null`(@TempDir tempDir: Path) = runTest {
         val fake = FakeCalendarDataSource().apply {
             eventDetailResult = { null }
         }
-        val repo = CalendarRepositoryImpl(fake, Dispatchers.Unconfined)
+        val repo = CalendarRepositoryImpl(fake, newPrefs(tempDir), Dispatchers.Unconfined)
 
         try {
             repo.eventDetail(eventId = 999L)

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

@@ -1,7 +1,14 @@
 package de.jeanlucmakiola.calendula.data.calendar
 
 import com.google.common.truth.Truth.assertThat
+import de.jeanlucmakiola.calendula.domain.AccessLevel
+import de.jeanlucmakiola.calendula.domain.AttendeeRelationship
 import de.jeanlucmakiola.calendula.domain.AttendeeStatus
+import de.jeanlucmakiola.calendula.domain.AttendeeType
+import de.jeanlucmakiola.calendula.domain.Availability
+import de.jeanlucmakiola.calendula.domain.EventStatus
+import de.jeanlucmakiola.calendula.domain.Reminder
+import de.jeanlucmakiola.calendula.domain.ReminderMethod
 import org.junit.jupiter.api.Test
 
 class EventDetailMapperTest {
@@ -19,6 +26,11 @@ class EventDetailMapperTest {
         allDay: Int = 0,
         location: String? = "Berlin",
         calendarId: Long = 7L,
+        status: Any? = null,
+        availability: Any? = null,
+        accessLevel: Any? = null,
+        timezone: String? = null,
+        selfStatus: Any? = null,
     ): MapColumnReader = MapColumnReader(
         EventDetailProjection.IDX_EVENT_ID to eventId,
         EventDetailProjection.IDX_TITLE to title,
@@ -32,18 +44,42 @@ class EventDetailMapperTest {
         EventDetailProjection.IDX_ALL_DAY to allDay,
         EventDetailProjection.IDX_LOCATION to location,
         EventDetailProjection.IDX_CALENDAR_ID to calendarId,
+        EventDetailProjection.IDX_STATUS to status,
+        EventDetailProjection.IDX_AVAILABILITY to availability,
+        EventDetailProjection.IDX_ACCESS_LEVEL to accessLevel,
+        EventDetailProjection.IDX_EVENT_TIMEZONE to timezone,
+        EventDetailProjection.IDX_SELF_ATTENDEE_STATUS to selfStatus,
     )
 
-    private fun attendeeReader(name: String?, email: String?, status: Int): MapColumnReader =
+    private fun attendeeReader(
+        name: String?,
+        email: String?,
+        status: Int,
+        relationship: Int = 0,
+        type: Int = 0,
+    ): MapColumnReader =
         MapColumnReader(
             AttendeeProjection.IDX_NAME to name,
             AttendeeProjection.IDX_EMAIL to email,
             AttendeeProjection.IDX_STATUS to status,
+            AttendeeProjection.IDX_RELATIONSHIP to relationship,
+            AttendeeProjection.IDX_TYPE to type,
         )
 
+    private fun reminderReader(minutes: Int, method: Int): MapColumnReader =
+        MapColumnReader(
+            ReminderProjection.IDX_MINUTES to minutes,
+            ReminderProjection.IDX_METHOD to method,
+        )
+
+    private fun MapColumnReader.toDetail(
+        attendees: List<de.jeanlucmakiola.calendula.domain.Attendee> = emptyList(),
+        reminders: List<Reminder> = emptyList(),
+    ) = toEventDetailCore(attendees, reminders)
+
     @Test
     fun `happy path detail maps all fields and embeds matching EventInstance`() {
-        val detail = detailReader().toEventDetailCore(attendees = emptyList())
+        val detail = detailReader().toDetail()
         assertThat(detail).isNotNull()
         assertThat(detail!!.description).isEqualTo("Body")
         assertThat(detail.organizer).isEqualTo("x@y")
@@ -55,21 +91,19 @@ class EventDetailMapperTest {
     @Test
     fun `event color falls back to calendar color when null`() {
         val detail = detailReader(eventColor = null, calendarColor = 0xFF112233.toInt())
-            .toEventDetailCore(attendees = emptyList())
+            .toDetail()
         assertThat(detail!!.instance.color).isEqualTo(0xFF112233.toInt())
     }
 
     @Test
     fun `dtend before dtstart drops detail`() {
-        val detail = detailReader(dtstart = 2000L, dtend = 1000L)
-            .toEventDetailCore(attendees = emptyList())
+        val detail = detailReader(dtstart = 2000L, dtend = 1000L).toDetail()
         assertThat(detail).isNull()
     }
 
     @Test
     fun `rrule passes through when present`() {
-        val detail = detailReader(rrule = "FREQ=WEEKLY;BYDAY=MO")
-            .toEventDetailCore(attendees = emptyList())
+        val detail = detailReader(rrule = "FREQ=WEEKLY;BYDAY=MO").toDetail()
         assertThat(detail!!.rrule).isEqualTo("FREQ=WEEKLY;BYDAY=MO")
     }
 
@@ -104,4 +138,82 @@ class EventDetailMapperTest {
         assertThat(attendeeReader("A", null, 1).toAttendee().email).isNull()
         assertThat(attendeeReader("A", "x@y", 1).toAttendee().email).isEqualTo("x@y")
     }
+
+    // RELATIONSHIP: NONE=0, ATTENDEE=1, ORGANIZER=2, PERFORMER=3, SPEAKER=4
+    @Test
+    fun `attendee relationship maps known integer codes`() {
+        assertThat(attendeeReader("A", "a@x", 1, relationship = 2).toAttendee().relationship)
+            .isEqualTo(AttendeeRelationship.Organizer)
+        assertThat(attendeeReader("A", "a@x", 1, relationship = 1).toAttendee().relationship)
+            .isEqualTo(AttendeeRelationship.Attendee)
+        assertThat(attendeeReader("A", "a@x", 1, relationship = 0).toAttendee().relationship)
+            .isEqualTo(AttendeeRelationship.None)
+    }
+
+    // TYPE: NONE=0, REQUIRED=1, OPTIONAL=2, RESOURCE=3
+    @Test
+    fun `attendee type maps known integer codes`() {
+        assertThat(attendeeReader("A", "a@x", 1, type = 1).toAttendee().type)
+            .isEqualTo(AttendeeType.Required)
+        assertThat(attendeeReader("A", "a@x", 1, type = 2).toAttendee().type)
+            .isEqualTo(AttendeeType.Optional)
+        assertThat(attendeeReader("A", "a@x", 1, type = 3).toAttendee().type)
+            .isEqualTo(AttendeeType.Resource)
+    }
+
+    // STATUS: TENTATIVE=0, CONFIRMED=1, CANCELED=2
+    @Test
+    fun `event status null maps to confirmed, codes map through`() {
+        assertThat(detailReader(status = null).toDetail()!!.status).isEqualTo(EventStatus.Confirmed)
+        assertThat(detailReader(status = 0).toDetail()!!.status).isEqualTo(EventStatus.Tentative)
+        assertThat(detailReader(status = 1).toDetail()!!.status).isEqualTo(EventStatus.Confirmed)
+        assertThat(detailReader(status = 2).toDetail()!!.status).isEqualTo(EventStatus.Cancelled)
+    }
+
+    // AVAILABILITY: BUSY=0, FREE=1, TENTATIVE=2
+    @Test
+    fun `availability null or busy maps to Busy, free maps to Free`() {
+        assertThat(detailReader(availability = null).toDetail()!!.availability)
+            .isEqualTo(Availability.Busy)
+        assertThat(detailReader(availability = 0).toDetail()!!.availability)
+            .isEqualTo(Availability.Busy)
+        assertThat(detailReader(availability = 1).toDetail()!!.availability)
+            .isEqualTo(Availability.Free)
+    }
+
+    // ACCESS_LEVEL: DEFAULT=0, CONFIDENTIAL=1, PRIVATE=2, PUBLIC=3
+    @Test
+    fun `access level maps known integer codes, null is Default`() {
+        assertThat(detailReader(accessLevel = null).toDetail()!!.accessLevel)
+            .isEqualTo(AccessLevel.Default)
+        assertThat(detailReader(accessLevel = 1).toDetail()!!.accessLevel)
+            .isEqualTo(AccessLevel.Confidential)
+        assertThat(detailReader(accessLevel = 2).toDetail()!!.accessLevel)
+            .isEqualTo(AccessLevel.Private)
+    }
+
+    @Test
+    fun `event timezone and self status pass through`() {
+        val detail = detailReader(timezone = "Europe/Berlin", selfStatus = 1).toDetail()
+        assertThat(detail!!.eventTimezone).isEqualTo("Europe/Berlin")
+        assertThat(detail.selfStatus).isEqualTo(AttendeeStatus.Accepted)
+    }
+
+    @Test
+    fun `reminders pass through to the detail`() {
+        val reminders = listOf(Reminder(10, ReminderMethod.Alert))
+        val detail = detailReader().toDetail(reminders = reminders)
+        assertThat(detail!!.reminders).isEqualTo(reminders)
+    }
+
+    // METHOD: DEFAULT=0, ALERT=1, EMAIL=2, SMS=3, ALARM=4
+    @Test
+    fun `reminder maps minutes and method codes`() {
+        assertThat(reminderReader(10, 1).toReminder())
+            .isEqualTo(Reminder(10, ReminderMethod.Alert))
+        assertThat(reminderReader(60, 2).toReminder())
+            .isEqualTo(Reminder(60, ReminderMethod.Email))
+        assertThat(reminderReader(0, 0).toReminder())
+            .isEqualTo(Reminder(0, ReminderMethod.Default))
+    }
 }

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

@@ -0,0 +1,74 @@
+package de.jeanlucmakiola.calendula.data.prefs
+
+import androidx.datastore.core.DataStore
+import androidx.datastore.preferences.core.PreferenceDataStoreFactory
+import androidx.datastore.preferences.core.Preferences
+import com.google.common.truth.Truth.assertThat
+import kotlinx.coroutines.flow.first
+import kotlinx.coroutines.test.runTest
+import kotlinx.datetime.DayOfWeek
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.io.TempDir
+import java.nio.file.Path
+import java.util.Locale
+
+class SettingsPrefsTest {
+
+    private fun newDataStore(tempDir: Path): DataStore<Preferences> =
+        PreferenceDataStoreFactory.create(
+            produceFile = { tempDir.resolve("settings_test.preferences_pb").toFile() },
+        )
+
+    @Test
+    fun `defaults are system theme, dynamic colour on, auto week start`(@TempDir tempDir: Path) = runTest {
+        val prefs = SettingsPrefs(newDataStore(tempDir))
+        assertThat(prefs.themeMode.first()).isEqualTo(ThemeMode.SYSTEM)
+        assertThat(prefs.dynamicColor.first()).isTrue()
+        assertThat(prefs.weekStart.first()).isEqualTo(WeekStartPref.AUTO)
+    }
+
+    @Test
+    fun `theme mode round-trips`(@TempDir tempDir: Path) = runTest {
+        val prefs = SettingsPrefs(newDataStore(tempDir))
+        prefs.setThemeMode(ThemeMode.DARK)
+        assertThat(prefs.themeMode.first()).isEqualTo(ThemeMode.DARK)
+    }
+
+    @Test
+    fun `dynamic colour round-trips`(@TempDir tempDir: Path) = runTest {
+        val prefs = SettingsPrefs(newDataStore(tempDir))
+        prefs.setDynamicColor(false)
+        assertThat(prefs.dynamicColor.first()).isFalse()
+    }
+
+    @Test
+    fun `week start round-trips`(@TempDir tempDir: Path) = runTest {
+        val prefs = SettingsPrefs(newDataStore(tempDir))
+        prefs.setWeekStart(WeekStartPref.SUNDAY)
+        assertThat(prefs.weekStart.first()).isEqualTo(WeekStartPref.SUNDAY)
+    }
+
+    @Test
+    fun `garbage stored enum falls back to default`(@TempDir tempDir: Path) = runTest {
+        val store = newDataStore(tempDir)
+        val prefs = SettingsPrefs(store)
+        store.updateData { p ->
+            val m = p.toMutablePreferences()
+            m[SettingsPrefs.THEME_MODE_KEY] = "PLAID"
+            m
+        }
+        assertThat(prefs.themeMode.first()).isEqualTo(ThemeMode.SYSTEM)
+    }
+
+    @Test
+    fun `explicit week-start prefs resolve regardless of locale`() {
+        assertThat(WeekStartPref.MONDAY.resolveFirstDay(Locale.US)).isEqualTo(DayOfWeek.MONDAY)
+        assertThat(WeekStartPref.SUNDAY.resolveFirstDay(Locale.GERMANY)).isEqualTo(DayOfWeek.SUNDAY)
+    }
+
+    @Test
+    fun `auto week start follows the locale convention`() {
+        assertThat(WeekStartPref.AUTO.resolveFirstDay(Locale.GERMANY)).isEqualTo(DayOfWeek.MONDAY)
+        assertThat(WeekStartPref.AUTO.resolveFirstDay(Locale.US)).isEqualTo(DayOfWeek.SUNDAY)
+    }
+}

app/src/test/java/de/jeanlucmakiola/calendula/ui/filter/FilterGroupingTest.kt

@@ -0,0 +1,61 @@
+package de.jeanlucmakiola.calendula.ui.filter
+
+import com.google.common.truth.Truth.assertThat
+import de.jeanlucmakiola.calendula.domain.CalendarSource
+import org.junit.jupiter.api.Test
+
+class FilterGroupingTest {
+
+    private fun cal(
+        id: Long,
+        name: String,
+        account: String,
+        type: String = "com.example",
+    ) = CalendarSource(
+        id = id,
+        displayName = name,
+        accountName = account,
+        accountType = type,
+        color = 0xFF336699.toInt(),
+        isVisibleInSystem = true,
+    )
+
+    @Test
+    fun `groups calendars under their account, preserving order`() {
+        val calendars = listOf(
+            cal(1, "Personal", "alice@dav"),
+            cal(2, "Work", "alice@dav"),
+            cal(3, "Shared", "team@dav"),
+        )
+
+        val groups = groupByAccount(calendars, hidden = emptySet())
+
+        assertThat(groups.map { it.account }).containsExactly("alice@dav", "team@dav").inOrder()
+        assertThat(groups[0].calendars.map { it.displayName })
+            .containsExactly("Personal", "Work").inOrder()
+        assertThat(groups[1].calendars.map { it.id }).containsExactly(3L)
+    }
+
+    @Test
+    fun `hidden ids mark calendars not visible`() {
+        val calendars = listOf(
+            cal(1, "Personal", "alice@dav"),
+            cal(2, "Work", "alice@dav"),
+        )
+
+        val groups = groupByAccount(calendars, hidden = setOf(2L))
+        val rows = groups.single().calendars.associateBy { it.id }
+
+        assertThat(rows.getValue(1L).visible).isTrue()
+        assertThat(rows.getValue(2L).visible).isFalse()
+    }
+
+    @Test
+    fun `blank account name falls back to type`() {
+        val groups = groupByAccount(
+            listOf(cal(1, "Birthdays", account = "", type = "LOCAL")),
+            hidden = emptySet(),
+        )
+        assertThat(groups.single().account).isEqualTo("LOCAL")
+    }
+}

docs/superpowers/specs/2026-06-08-calendar-app-design.md

@@ -27,7 +27,7 @@ von Google Calendar gibt - speziell mit dem 2025er Expressive-Design.
 - 3 Hauptansichten: Monat, Woche, Tag
 - Event-Detail-Sheet (read-only Detailansicht)
 - Multi-Kalender-Toggle (Sichtbarkeit pro Kalender)
-- Heute-Button + Jump-to-Date
+- Heute-Button (Jump-to-Date gestrichen, siehe Out-of-Scope)
 - Settings-Screen (Theme, Dynamic Color, Wochenstart, Sprache)
 - Permission-Flow für `READ_CALENDAR`
 - Empty-States und Error-Recovery
@@ -35,6 +35,7 @@ von Google Calendar gibt - speziell mit dem 2025er Expressive-Design.
 - Tests + CI ab Tag 1
 
 ### Out-of-Scope (V2+)
+- Jump-to-Date / Datum-Picker (aus V1-Scope gestrichen)
 - Event-Create/Edit/Delete (V2)
 - Home-Screen-Widget
 - Volltextsuche
@@ -202,9 +203,9 @@ fragt Repository nur für sichtbaren Range an - kein "alle Events der Welt".
 - Immer erreichbar von allen Hauptansichten
 - State persistent (zuletzt aktive Ansicht)
 
-**M2 - Heute / Springe-zu-Datum**
-- Schnell zurück zu "heute"
-- Springe zu beliebigem Datum via Datum-Picker
+**M2 - Heute**
+- Schnell zurück zu "heute" (Drawer-Eintrag, ausgeliefert in v0.5)
+- ~~Springe zu beliebigem Datum via Datum-Picker~~ — **gestrichen**, siehe Out-of-Scope
 - Erreichbar von allen Hauptansichten
 
 **M3 - Kalender-Filter (Bottom-Sheet)**

gradle/libs.versions.toml

@@ -4,6 +4,7 @@ kotlin = "2.3.21"
 ksp = "2.3.9"
 hilt = "2.59.2"
 coreKtx = "1.19.0"
+appcompat = "1.7.1"
 lifecycleRuntime = "2.10.0"
 activityCompose = "1.13.0"
 composeBom = "2026.05.01"
@@ -27,6 +28,7 @@ androidxTestRules = "1.7.0"
 [libraries]
 # AndroidX core
 androidx-core-ktx = { group = "androidx.core", name = "core-ktx", version.ref = "coreKtx" }
+androidx-appcompat = { group = "androidx.appcompat", name = "appcompat", version.ref = "appcompat" }
 androidx-lifecycle-runtime-ktx = { group = "androidx.lifecycle", name = "lifecycle-runtime-ktx", version.ref = "lifecycleRuntime" }
 androidx-activity-compose = { group = "androidx.activity", name = "activity-compose", version.ref = "activityCompose" }
 
@@ -42,6 +44,7 @@ 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" }