release: cut v2.4.0 — per-event colors

Optional per-event color in the event form. The read/render path already
resolved EVENT_COLOR with a calendar fallback; this adds the write side and
the picker.

- Palette-backed calendars (Google, some CalDAV) pick from the account's
  Colors (TYPE_EVENT) and write EVENT_COLOR_KEY, so the color round-trips
  through sync; local calendars write a raw EVENT_COLOR from the shared
  CALENDAR_COLOR_PALETTE. Never writes a raw color to a palette calendar.
- Swatch row + palette extracted to ui/common/ColorSwatchRow.kt (shared with
  the calendar editor). Switching calendars resets the choice (keys are
  account-scoped); a "Reset" action returns to the calendar color.
- New "Allow colors on unsupported calendars" setting (off by default)
  extends the raw path to no-palette synced calendars, with an honest
  "may not survive sync" warning on the picker and in Settings.
- Color flows through insert / dirty-checked update / occurrence-exception;
  mapper, form, and repository tests added.

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

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

@@ -7,6 +7,7 @@ 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.EventColorOption
 import de.jeanlucmakiola.calendula.domain.EventForm
 import de.jeanlucmakiola.calendula.domain.EventInstance
 import kotlinx.coroutines.Dispatchers
@@ -400,4 +401,20 @@ class CalendarRepositoryImplTest {
             assertThat(expected.message).contains("999")
         }
     }
+
+    @Test
+    fun `eventColorPalette delegates to the data source for the given calendar`(
+        @TempDir tempDir: Path,
+    ) = runTest {
+        val fake = FakeCalendarDataSource().apply {
+            eventColorPaletteResult = { id ->
+                if (id == 7L) listOf(EventColorOption("5", 0xFF33B679.toInt())) else emptyList()
+            }
+        }
+        val repo = CalendarRepositoryImpl(fake, newPrefs(tempDir), Dispatchers.Unconfined)
+
+        assertThat(repo.eventColorPalette(7L))
+            .containsExactly(EventColorOption("5", 0xFF33B679.toInt()))
+        assertThat(repo.eventColorPalette(8L)).isEmpty()
+    }
 }

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

@@ -20,6 +20,7 @@ class EventDetailMapperTest {
         organizer: String? = "x@y",
         rrule: String? = null,
         eventColor: Any? = null,
+        eventColorKey: String? = null,
         calendarColor: Int = 0xFFAABBCC.toInt(),
         dtstart: Long = 1_000_000_000L,
         dtend: Long = 1_000_003_600L,
@@ -49,6 +50,7 @@ class EventDetailMapperTest {
         EventDetailProjection.IDX_ACCESS_LEVEL to accessLevel,
         EventDetailProjection.IDX_EVENT_TIMEZONE to timezone,
         EventDetailProjection.IDX_SELF_ATTENDEE_STATUS to selfStatus,
+        EventDetailProjection.IDX_EVENT_COLOR_KEY to eventColorKey,
     )
 
     private fun attendeeReader(
@@ -99,6 +101,22 @@ class EventDetailMapperTest {
         val detail = detailReader(eventColor = null, calendarColor = 0xFF112233.toInt())
             .toDetail()
         assertThat(detail!!.instance.color).isEqualTo(0xFF112233.toInt())
+        // No own colour: the edit form must see this as "inherits".
+        assertThat(detail.eventColor).isNull()
+        assertThat(detail.eventColorKey).isNull()
+    }
+
+    @Test
+    fun `own event color and key are surfaced apart from the resolved color`() {
+        val detail = detailReader(
+            eventColor = 0xFF33B679.toInt(),
+            eventColorKey = "5",
+            calendarColor = 0xFF112233.toInt(),
+        ).toDetail()
+        // Resolved display colour is the event's own, not the calendar fallback.
+        assertThat(detail!!.instance.color).isEqualTo(0xFF33B679.toInt())
+        assertThat(detail.eventColor).isEqualTo(0xFF33B679.toInt())
+        assertThat(detail.eventColorKey).isEqualTo("5")
     }
 
     @Test

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

@@ -218,4 +218,83 @@ class EventWriteMapperTest {
         assertThat(values).containsEntry(CalendarContract.Events.EVENT_LOCATION, null)
         assertThat(values).containsEntry(CalendarContract.Events.DESCRIPTION, null)
     }
+
+    // --- per-event colour ---
+
+    @Test
+    fun `palette colour writes only the key, never a raw colour`() {
+        assertThat(eventColorColumns(colorKey = "5", color = 0xFF33B679.toInt()))
+            .containsExactly(CalendarContract.Events.EVENT_COLOR_KEY, "5")
+    }
+
+    @Test
+    fun `raw colour writes the colour and clears any key`() {
+        assertThat(eventColorColumns(colorKey = null, color = 0xFF8E24AA.toInt()))
+            .containsExactly(
+                CalendarContract.Events.EVENT_COLOR_KEY, null,
+                CalendarContract.Events.EVENT_COLOR, 0xFF8E24AA.toInt(),
+            )
+    }
+
+    @Test
+    fun `no colour clears both columns so the event inherits its calendar`() {
+        assertThat(eventColorColumns(colorKey = null, color = null))
+            .containsExactly(
+                CalendarContract.Events.EVENT_COLOR_KEY, null,
+                CalendarContract.Events.EVENT_COLOR, null,
+            )
+    }
+
+    @Test
+    fun `setting a palette colour on update writes just the key`() {
+        val original = form()
+        val values = update(original, original.copy(colorKey = "3", color = 0xFFF6BF26.toInt()))
+        assertThat(values).containsExactly(CalendarContract.Events.EVENT_COLOR_KEY, "3")
+    }
+
+    @Test
+    fun `setting a raw colour on update writes the colour and a null key`() {
+        val original = form()
+        val values = update(original, original.copy(color = 0xFF039BE5.toInt()))
+        assertThat(values).containsEntry(CalendarContract.Events.EVENT_COLOR, 0xFF039BE5.toInt())
+        assertThat(values).containsEntry(CalendarContract.Events.EVENT_COLOR_KEY, null)
+    }
+
+    @Test
+    fun `clearing a colour on update writes explicit nulls`() {
+        val original = form().copy(color = 0xFFD50000.toInt())
+        val values = update(original, original.copy(color = null))
+        assertThat(values).containsEntry(CalendarContract.Events.EVENT_COLOR, null)
+        assertThat(values).containsEntry(CalendarContract.Events.EVENT_COLOR_KEY, null)
+    }
+
+    @Test
+    fun `unchanged colour writes no colour columns`() {
+        val original = form().copy(colorKey = "7", color = 0xFF3F51B5.toInt())
+        val values = update(original, original.copy(title = "Renamed"))
+        assertThat(values).doesNotContainKey(CalendarContract.Events.EVENT_COLOR_KEY)
+        assertThat(values).doesNotContainKey(CalendarContract.Events.EVENT_COLOR)
+    }
+
+    @Test
+    fun `occurrence exception carries the palette key`() {
+        val values = buildOccurrenceExceptionValues(
+            form = form().copy(colorKey = "2", color = 0xFFE67C00.toInt()),
+            originalInstanceMillis = 0L,
+            zone = berlin,
+        )
+        assertThat(values).containsEntry(CalendarContract.Events.EVENT_COLOR_KEY, "2")
+        assertThat(values).doesNotContainKey(CalendarContract.Events.EVENT_COLOR)
+    }
+
+    @Test
+    fun `occurrence exception with no colour clears both columns`() {
+        val values = buildOccurrenceExceptionValues(
+            form = form(),
+            originalInstanceMillis = 0L,
+            zone = berlin,
+        )
+        assertThat(values).containsEntry(CalendarContract.Events.EVENT_COLOR, null)
+        assertThat(values).containsEntry(CalendarContract.Events.EVENT_COLOR_KEY, null)
+    }
 }

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

@@ -1,6 +1,7 @@
 package de.jeanlucmakiola.calendula.data.calendar
 
 import de.jeanlucmakiola.calendula.domain.CalendarSource
+import de.jeanlucmakiola.calendula.domain.EventColorOption
 import de.jeanlucmakiola.calendula.domain.EventDetail
 import de.jeanlucmakiola.calendula.domain.EventForm
 import de.jeanlucmakiola.calendula.domain.EventInstance
@@ -14,6 +15,7 @@ internal class FakeCalendarDataSource : CalendarDataSource {
     var calendarsResult: List<CalendarSource> = emptyList()
     var instancesResult: (Long, Long) -> List<EventInstance> = { _, _ -> emptyList() }
     var eventDetailResult: (Long) -> EventDetail? = { null }
+    var eventColorPaletteResult: (Long) -> List<EventColorOption> = { emptyList() }
     /** Set to make the next write call throw. */
     var writeError: Exception? = null
     /** Id returned by the next [insertEvent]. */
@@ -45,6 +47,8 @@ internal class FakeCalendarDataSource : CalendarDataSource {
     override fun instances(beginMillis: Long, endMillis: Long): List<EventInstance> =
         instancesResult(beginMillis, endMillis)
     override fun eventDetail(eventId: Long): EventDetail? = eventDetailResult(eventId)
+    override fun eventColorPalette(calendarId: Long): List<EventColorOption> =
+        eventColorPaletteResult(calendarId)
 
     override fun createLocalCalendar(displayName: String, color: Int, description: String?): Long {
         writeError?.let { throw it }

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

@@ -115,6 +115,8 @@ class EventFormTest {
         rowStart: Long = 0L,
         rowEnd: Long = 0L,
         attendees: List<Attendee> = emptyList(),
+        eventColor: Int? = null,
+        eventColorKey: String? = null,
     ): EventDetail = EventDetail(
         instance = EventInstance(
             instanceId = 1L,
@@ -134,6 +136,8 @@ class EventFormTest {
         reminders = reminders,
         availability = availability,
         accessLevel = accessLevel,
+        eventColor = eventColor,
+        eventColorKey = eventColorKey,
     )
 
     @Test
@@ -227,6 +231,7 @@ class EventFormTest {
             rrule = "FREQ=DAILY",
             availability = Availability.Free,
             accessLevel = AccessLevel.Private,
+            color = 0xFFD50000.toInt(),
         )
         assertThat(full.populatedFields()).containsExactly(
             EventFormField.Location,
@@ -235,6 +240,33 @@ class EventFormTest {
             EventFormField.Recurrence,
             EventFormField.Availability,
             EventFormField.Visibility,
+            EventFormField.Color,
         )
     }
+
+    @Test
+    fun `toEditForm carries a palette colour as key plus swatch`() {
+        val prefilled = detail(eventColor = 0xFF33B679.toInt(), eventColorKey = "5")
+            .toEditForm(beginMillis = 0L, endMillis = 3_600_000L, zone = berlin)
+        assertThat(prefilled.colorKey).isEqualTo("5")
+        assertThat(prefilled.color).isEqualTo(0xFF33B679.toInt())
+        assertThat(prefilled.populatedFields()).contains(EventFormField.Color)
+    }
+
+    @Test
+    fun `toEditForm carries a raw colour with no key`() {
+        val prefilled = detail(eventColor = 0xFF8E24AA.toInt())
+            .toEditForm(beginMillis = 0L, endMillis = 3_600_000L, zone = berlin)
+        assertThat(prefilled.colorKey).isNull()
+        assertThat(prefilled.color).isEqualTo(0xFF8E24AA.toInt())
+    }
+
+    @Test
+    fun `toEditForm leaves an inheriting event without a colour`() {
+        val prefilled = detail()
+            .toEditForm(beginMillis = 0L, endMillis = 3_600_000L, zone = berlin)
+        assertThat(prefilled.colorKey).isNull()
+        assertThat(prefilled.color).isNull()
+        assertThat(prefilled.populatedFields()).doesNotContain(EventFormField.Color)
+    }
 }