fix(detail): open events whose series starts before 1970 (#34)

DTSTART is stored as UTC epoch millis, so a recurring series anchored
before 1970-01-01 (common for yearly birthdays/anniversaries synced over
CalDAV) has a legitimately negative DTSTART. The detail and search
mappers dropped any row with dtstart < 0, and since the detail query
reads the series-master DTSTART (the ancient anchor), every occurrence of
such a series became un-openable — surfacing as the generic
"Something went wrong." error screen — and the events vanished from
search too.

Relax the guard to reject only an *absent* DTSTART (isNull), which is the
malformed case it was meant to catch; negative epoch millis flow through
correctly (Instant/formatting and the all-day reminder decode are all
Long-based). Add regression tests for both mappers.

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

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

@@ -23,12 +23,16 @@ internal fun ColumnReader.toEventDetailCore(
     attendees: List<Attendee>,
     reminders: List<Reminder>,
 ): EventDetail? {
-    val begin = getLong(EventDetailProjection.IDX_DTSTART)
+    // DTSTART is epoch millis in UTC, so a series anchored before 1970 (common
-
+    // for yearly birthdays/anniversaries synced over CalDAV) is legitimately
-    if (begin < 0L) {
+    // negative — only an *absent* DTSTART marks a malformed row worth dropping.
-        Log.w(TAG, "Dropping event with negative dtstart=$begin")
+    // Dropping negatives made every occurrence of such a series un-openable
+    // (the detail loads the ancient series-master DTSTART), see issue #34.
+    if (isNull(EventDetailProjection.IDX_DTSTART)) {
+        Log.w(TAG, "Dropping event with missing dtstart")
         return null
     }
+    val begin = getLong(EventDetailProjection.IDX_DTSTART)
 
     // Recurring events store DURATION instead of DTEND, so the series row's
     // DTEND is null. Keep the event (end == begin); callers that opened a

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

@@ -10,8 +10,11 @@ import de.jeanlucmakiola.calendula.domain.ics.parseRfc2445DurationMillis
  * of DTEND — reconstruct the end the same way the `.ics` export does.
  */
 internal fun ColumnReader.toSearchResult(): EventInstance? {
+    // A pre-1970 series anchor is a legitimately negative epoch-millis DTSTART
+    // (see EventDetailMapper / issue #34); drop only a genuinely absent one, so
+    // long-running birthdays/anniversaries still surface in search.
+    if (isNull(SearchProjection.IDX_DTSTART)) return null
     val dtStart = getLong(SearchProjection.IDX_DTSTART)
-    if (dtStart < 0L) return null
     val end = when {
         !isNull(SearchProjection.IDX_DTEND) -> getLong(SearchProjection.IDX_DTEND)
         else -> dtStart + parseRfc2445DurationMillis(getString(SearchProjection.IDX_DURATION))

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

@@ -22,8 +22,8 @@ class EventDetailMapperTest {
         eventColor: Any? = null,
         eventColorKey: String? = null,
         calendarColor: Int = 0xFFAABBCC.toInt(),
-        dtstart: Long = 1_000_000_000L,
+        dtstart: Long? = 1_000_000_000L,
-        dtend: Long = 1_000_003_600L,
+        dtend: Long? = 1_000_003_600L,
         allDay: Int = 0,
         location: String? = "Berlin",
         calendarId: Long = 7L,
@@ -125,6 +125,23 @@ class EventDetailMapperTest {
         assertThat(detail).isNull()
     }
 
+    @Test
+    fun `pre-1970 negative dtstart is kept, not dropped (issue #34)`() {
+        // A yearly birthday/anniversary anchored before the epoch has a
+        // legitimately negative UTC epoch-millis DTSTART; recurring rows carry
+        // no DTEND (they use DURATION), so it stays end == begin.
+        val begin = -157_766_400_000L // 1965-01-01T00:00:00Z
+        val detail = detailReader(dtstart = begin, dtend = null).toDetail()
+        assertThat(detail).isNotNull()
+        assertThat(detail!!.instance.start.toEpochMilliseconds()).isEqualTo(begin)
+        assertThat(detail.instance.end.toEpochMilliseconds()).isEqualTo(begin)
+    }
+
+    @Test
+    fun `absent dtstart drops detail`() {
+        assertThat(detailReader(dtstart = null).toDetail()).isNull()
+    }
+
     @Test
     fun `rrule passes through when present`() {
         val detail = detailReader(rrule = "FREQ=WEEKLY;BYDAY=MO").toDetail()

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

@@ -0,0 +1,45 @@
+package de.jeanlucmakiola.calendula.data.calendar
+
+import com.google.common.truth.Truth.assertThat
+import org.junit.jupiter.api.Test
+
+class SearchMapperTest {
+
+    private fun searchReader(
+        id: Long = 1L,
+        calendarId: Long = 7L,
+        title: String? = "Birthday",
+        dtstart: Long? = 1_000_000_000L,
+        dtend: Long? = null,
+        duration: String? = "P1D",
+        allDay: Int = 1,
+        eventColor: Any? = null,
+        calendarColor: Int = 0xFFAABBCC.toInt(),
+        location: String? = null,
+    ): MapColumnReader = MapColumnReader(
+        SearchProjection.IDX_ID to id,
+        SearchProjection.IDX_CALENDAR_ID to calendarId,
+        SearchProjection.IDX_TITLE to title,
+        SearchProjection.IDX_DTSTART to dtstart,
+        SearchProjection.IDX_DTEND to dtend,
+        SearchProjection.IDX_DURATION to duration,
+        SearchProjection.IDX_ALL_DAY to allDay,
+        SearchProjection.IDX_EVENT_COLOR to eventColor,
+        SearchProjection.IDX_CALENDAR_COLOR to calendarColor,
+        SearchProjection.IDX_LOCATION to location,
+    )
+
+    @Test
+    fun `pre-1970 negative dtstart still surfaces in search (issue #34)`() {
+        val begin = -157_766_400_000L // 1965-01-01T00:00:00Z
+        val result = searchReader(dtstart = begin, dtend = null, duration = "P1D").toSearchResult()
+        assertThat(result).isNotNull()
+        assertThat(result!!.start.toEpochMilliseconds()).isEqualTo(begin)
+        assertThat(result.title).isEqualTo("Birthday")
+    }
+
+    @Test
+    fun `absent dtstart drops the search hit`() {
+        assertThat(searchReader(dtstart = null).toSearchResult()).isNull()
+    }
+}