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

@@ -71,9 +71,11 @@ interface CalendarDataSource {
     /**
      * Every master/one-off event of the writable local calendars, mapped for a
      * whole-calendar `.ics` backup. Modified-occurrence and cancelled-exception
-     * rows are excluded (see [EventExportProjection]).
+     * rows are excluded (see [EventExportProjection]). When [calendarIds] is
+     * given, only those calendars are exported (still intersected with the
+     * eligible set); `null` exports every eligible calendar.
      */
-    fun exportableEvents(): List<IcsEvent>
+    fun exportableEvents(calendarIds: Set<Long>? = null): List<IcsEvent>
 
     /**
      * The non-empty `Events.UID_2445` values present in [calendarId] — used to
@@ -611,15 +613,19 @@ class AndroidCalendarDataSource @Inject constructor(
             ?: emptyList()
     }
 
-    override fun exportableEvents(): List<IcsEvent> {
+    override fun exportableEvents(calendarIds: Set<Long>?): List<IcsEvent> {
         // Only the local calendars the app owns and can write — synced calendars
         // already have a backup (their server). Exclude the managed special-dates
         // mirror calendars: their events are derived from contacts, not authored
         // here, and re-materialise from the contact sync — backing them up would
-        // just duplicate them on restore. Map id → display name for the
+        // just duplicate them on restore. A non-null [calendarIds] narrows the
+        // export to the user's chosen subset. Map id → display name for the
         // X-CALENDULA-CALENDAR tag a restore uses to fan back out.
         val names = calendars()
-            .filter { it.isLocal && it.canModifyContents && !it.isManaged }
+            .filter {
+                it.isLocal && it.canModifyContents && !it.isManaged &&
+                    (calendarIds == null || it.id in calendarIds)
+            }
             .associate { it.id to it.displayName }
         if (names.isEmpty()) return emptyList()
 

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

@@ -41,8 +41,9 @@ interface CalendarRepository {
     /**
      * Every event of the writable local calendars, ready to serialise into a
      * whole-calendar `.ics` backup (see [CalendarDataSource.exportableEvents]).
+     * [calendarIds] narrows the export to a chosen subset; `null` exports all.
      */
-    suspend fun exportEvents(): List<IcsEvent>
+    suspend fun exportEvents(calendarIds: Set<Long>? = null): List<IcsEvent>
 
     /**
      * Bulk-import parsed `.ics` [events] into [targetCalendarId]. Events whose

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

@@ -117,7 +117,8 @@ class CalendarRepositoryImpl @Inject constructor(
     override suspend fun deleteCalendar(id: Long) =
         withContext(io) { dataSource.deleteCalendar(id) }
 
-    override suspend fun exportEvents() = withContext(io) { dataSource.exportableEvents() }
+    override suspend fun exportEvents(calendarIds: Set<Long>?) =
+        withContext(io) { dataSource.exportableEvents(calendarIds) }
 
     override suspend fun importEvents(
         targetCalendarId: Long,

app/src/main/java/de/jeanlucmakiola/calendula/ui/calendars/CalendarsScreen.kt

@@ -46,6 +46,7 @@ import androidx.compose.material.icons.filled.Visibility
 import androidx.compose.material.icons.filled.VisibilityOff
 import androidx.compose.material3.AlertDialog
 import androidx.compose.material3.Button
+import androidx.compose.material3.Checkbox
 import androidx.compose.material3.DropdownMenu
 import androidx.compose.material3.DropdownMenuItem
 import androidx.compose.material3.ExperimentalMaterial3Api
@@ -97,6 +98,8 @@ import de.jeanlucmakiola.calendula.data.prefs.SettingsPrefs
 import de.jeanlucmakiola.calendula.domain.CalendarSource
 import de.jeanlucmakiola.calendula.data.calendar.CalendarColorPalette
 import de.jeanlucmakiola.calendula.ui.common.CalendarColorChip
+import de.jeanlucmakiola.calendula.ui.common.FullScreenPicker
+import de.jeanlucmakiola.calendula.ui.common.positionOf
 import de.jeanlucmakiola.calendula.ui.common.LeadingAvatar
 import de.jeanlucmakiola.calendula.ui.common.SourceLogo
 import de.jeanlucmakiola.calendula.ui.common.curatedSourcePackage
@@ -206,7 +209,7 @@ private fun CalendarsList(
     error: Boolean,
     onConsumeError: () -> Unit,
     backupResult: BackupResult?,
-    onExportBackup: (android.net.Uri) -> Unit,
+    onExportBackup: (android.net.Uri, Set<Long>?) -> Unit,
     onImport: (android.net.Uri) -> Unit,
     onConsumeBackupResult: () -> Unit,
     autoBackup: AutoBackupUiState,
@@ -235,10 +238,12 @@ private fun CalendarsList(
     }
 
     // SAF "create document" target for the backup file. The picked Uri is handed
-    // to the VM to stream the .ics into.
+    // to the VM to stream the .ics into. This launcher exports everything
+    // eligible (null); the per-calendar selector owns its own launcher.
     val createBackup = rememberLauncherForActivityResult(
         contract = ActivityResultContracts.CreateDocument("text/calendar"),
-    ) { uri -> uri?.let(onExportBackup) }
+    ) { uri -> uri?.let { onExportBackup(it, null) } }
+    var showExportPicker by remember { mutableStateOf(false) }
 
     // SAF "open document" picker for restoring events from a .ics file. The
     // picked Uri is handed up to the host, which runs it through the same import
@@ -325,8 +330,10 @@ private fun CalendarsList(
         }
 
         // Backup — local calendars have no sync, so a .ics export is their only
-        // safety net. Offered only when there is something to back up.
-        if (local.isNotEmpty()) {
+        // safety net. Offered only when there is something exportable: the user's
+        // own local calendars (managed special-dates mirrors don't count).
+        val exportable = local.filter { it.canModifyContents && !it.isManaged }
+        if (exportable.isNotEmpty()) {
             Spacer(Modifier.height(16.dp))
             SectionHeader(stringResource(R.string.calendars_backup_header))
             HintText(stringResource(R.string.calendars_backup_hint))
@@ -337,7 +344,13 @@ private fun CalendarsList(
                 position = Position.Top,
                 leading = { LeadingAvatar(Icons.Default.FileDownload) },
                 onClick = {
-                    runCatching { createBackup.launch("calendula-backup-${LocalDate.now()}.ics") }
+                    // With more than one exportable calendar, let the user choose
+                    // which to include; a single one exports straight away.
+                    if (exportable.size == 1) {
+                        runCatching { createBackup.launch("calendula-backup-${LocalDate.now()}.ics") }
+                    } else {
+                        showExportPicker = true
+                    }
                 },
             )
             GroupedRow(
@@ -441,6 +454,76 @@ private fun CalendarsList(
             onDismiss = { showInterval = false },
         )
     }
+
+    if (showExportPicker) {
+        ExportCalendarPicker(
+            calendars = local.filter { it.canModifyContents && !it.isManaged },
+            onExport = onExportBackup,
+            onDismiss = { showExportPicker = false },
+        )
+    }
+}
+
+/**
+ * Choose which local calendars to include in a one-time `.ics` export. Defaults
+ * to all selected; the Export action opens the SAF save dialog and hands back
+ * the picked file with the chosen calendar ids.
+ */
+@Composable
+private fun ExportCalendarPicker(
+    calendars: List<CalendarSource>,
+    onExport: (android.net.Uri, Set<Long>?) -> Unit,
+    onDismiss: () -> Unit,
+) {
+    var selected by remember(calendars) {
+        mutableStateOf(calendars.map { it.id }.toSet())
+    }
+    val createBackup = rememberLauncherForActivityResult(
+        contract = ActivityResultContracts.CreateDocument("text/calendar"),
+    ) { uri ->
+        if (uri != null) {
+            onExport(uri, selected)
+            onDismiss()
+        }
+    }
+
+    FullScreenPicker(
+        title = stringResource(R.string.calendars_export_title),
+        onDismiss = onDismiss,
+    ) {
+        HintText(stringResource(R.string.calendars_export_hint))
+        calendars.forEachIndexed { index, calendar ->
+            val isSelected = calendar.id in selected
+            GroupedRow(
+                title = calendar.displayName,
+                summary = calendar.description,
+                position = positionOf(index, calendars.size),
+                leading = { CalendarColorChip(calendar.color) },
+                trailing = {
+                    Checkbox(
+                        checked = isSelected,
+                        onCheckedChange = { checked ->
+                            selected = if (checked) selected + calendar.id else selected - calendar.id
+                        },
+                    )
+                },
+                onClick = {
+                    selected = if (isSelected) selected - calendar.id else selected + calendar.id
+                },
+            )
+        }
+        Button(
+            onClick = {
+                runCatching { createBackup.launch("calendula-backup-${LocalDate.now()}.ics") }
+            },
+            enabled = selected.isNotEmpty(),
+            modifier = Modifier
+                .fillMaxWidth()
+                .padding(horizontal = 16.dp, vertical = 16.dp),
+        ) {
+            Text(stringResource(R.string.calendars_export_action))
+        }
+    }
 }
 
 @OptIn(ExperimentalMaterial3Api::class)

app/src/main/java/de/jeanlucmakiola/calendula/ui/calendars/CalendarsViewModel.kt

@@ -107,11 +107,11 @@ class CalendarsViewModel @Inject constructor(
      * document [uri] as one `VCALENDAR`. Result (event count, or failure) lands
      * in [backupResult] for a one-shot message.
      */
-    fun exportBackup(uri: Uri) {
+    fun exportBackup(uri: Uri, calendarIds: Set<Long>? = null) {
         viewModelScope.launch {
             _backupResult.value = try {
                 val count = withContext(io) {
-                    val events = repository.exportEvents()
+                    val events = repository.exportEvents(calendarIds)
                     icsExporter.writeDocument(
                         uri = uri,
                         content = IcsWriter().writeCalendar(events, Clock.System.now()),

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

@@ -428,6 +428,9 @@
     <string name="calendars_backup_header">Backup</string>
     <string name="calendars_backup_hint">Local calendars aren\'t synced anywhere, so export them to an .ics file to keep a copy.</string>
     <string name="calendars_backup_action">Export as .ics file</string>
+    <string name="calendars_export_title">Export calendars</string>
+    <string name="calendars_export_hint">Choose which calendars to include in the .ics file.</string>
+    <string name="calendars_export_action">Export</string>
     <string name="calendars_restore_action">Restore from .ics file</string>
     <string name="calendars_restore_hint">Import events from a backup or another calendar app.</string>
     <string name="calendars_auto_backup">Automatic backup</string>

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

@@ -59,7 +59,7 @@ internal class FakeCalendarDataSource : CalendarDataSource {
     override fun eventDetail(eventId: Long): EventDetail? = eventDetailResult(eventId)
     override fun eventColorPalette(calendarId: Long): List<EventColorOption> =
         eventColorPaletteResult(calendarId)
-    override fun exportableEvents(): List<IcsEvent> = exportableEventsResult
+    override fun exportableEvents(calendarIds: Set<Long>?): List<IcsEvent> = exportableEventsResult
 
     override fun existingUids(calendarId: Long): Set<String> = existingUidsResult