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

@@ -14,6 +14,7 @@ import kotlinx.coroutines.CoroutineDispatcher
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.MutableSharedFlow
 import kotlinx.coroutines.flow.combine
+import kotlinx.coroutines.flow.distinctUntilChanged
 import kotlinx.coroutines.flow.first
 import kotlinx.coroutines.flow.flow
 import kotlinx.coroutines.flow.flowOn
@@ -55,11 +56,12 @@ 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.
+    // Instances are filtered by the app-side hidden ∪ disabled calendar sets
+    // (M3): an event is dropped whenever the user has hidden *or* disabled its
+    // calendar. Re-runs when the provider ticks *or* either set changes —
+    // toggling a calendar in the filter sheet or the calendar manager updates
+    // every view immediately. [calendars] stays unfiltered so those screens can
+    // list and re-enable hidden/disabled calendars.
     override fun instances(range: ClosedRange<Instant>): Flow<List<EventInstance>> =
         combine(
             ticks
@@ -71,10 +73,17 @@ class CalendarRepositoryImpl @Inject constructor(
                     )
                 },
             prefs.hiddenCalendarIds,
-        ) { instances, hidden ->
-            if (hidden.isEmpty()) instances
-            else instances.filterNot { it.calendarId in hidden }
-        }.flowOn(io)
+            prefs.disabledCalendarIds,
+        ) { instances, hidden, disabled ->
+            val excluded = hidden + disabled
+            if (excluded.isEmpty()) instances
+            else instances.filterNot { it.calendarId in excluded }
+        }
+            // hidden and disabled both derive from one DataStore, so toggling
+            // either makes both re-emit and combine briefly surfaces the same
+            // list twice — collapse the duplicate so views don't re-render for it.
+            .distinctUntilChanged()
+            .flowOn(io)
 
     override suspend fun eventDetail(eventId: Long): EventDetail = withContext(io) {
         dataSource.eventDetail(eventId) ?: throw NoSuchEventException(eventId)
@@ -82,9 +91,9 @@ class CalendarRepositoryImpl @Inject constructor(
 
     override suspend fun searchEvents(query: String): List<EventInstance> = withContext(io) {
         if (query.isBlank()) return@withContext emptyList()
-        val hidden = prefs.hiddenCalendarIds.first()
+        val excluded = prefs.hiddenCalendarIds.first() + prefs.disabledCalendarIds.first()
         dataSource.searchEvents(query)
-            .let { if (hidden.isEmpty()) it else it.filterNot { e -> e.calendarId in hidden } }
+            .let { if (excluded.isEmpty()) it else it.filterNot { e -> e.calendarId in excluded } }
     }
 
     override suspend fun eventColorPalette(calendarId: Long): List<EventColorOption> =

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

@@ -39,6 +39,31 @@ class CalendarPrefs @Inject constructor(
         }
     }
 
+    /**
+     * App-side preference for "calendars the user has disabled in this app" — a
+     * heavier level than [hiddenCalendarIds]. A disabled calendar is removed from
+     * every surface (drawer filter, event-form picker, import picker) and its
+     * events never appear; it stays listed only in Settings → Calendars so it can
+     * be re-enabled. Stored exactly like the hidden set; never touches the
+     * system's VISIBLE/SYNC_EVENTS flags, so other calendar apps are unaffected.
+     */
+    val disabledCalendarIds: Flow<Set<Long>> = store.data.map { prefs ->
+        prefs[DISABLED_IDS_KEY].orEmpty()
+            .split(',')
+            .mapNotNull { it.trim().toLongOrNull() }
+            .toSet()
+    }
+
+    suspend fun setDisabledCalendarIds(ids: Set<Long>) {
+        store.edit { prefs ->
+            if (ids.isEmpty()) {
+                prefs.remove(DISABLED_IDS_KEY)
+            } else {
+                prefs[DISABLED_IDS_KEY] = ids.sorted().joinToString(",")
+            }
+        }
+    }
+
     /**
      * The calendar the user last created an event in; preselected in the
      * event form. Null until the first event is created.
@@ -53,6 +78,7 @@ class CalendarPrefs @Inject constructor(
 
     companion object {
         internal val HIDDEN_IDS_KEY = stringPreferencesKey("hidden_calendar_ids")
+        internal val DISABLED_IDS_KEY = stringPreferencesKey("disabled_calendar_ids")
         internal val LAST_USED_CALENDAR_KEY = longPreferencesKey("last_used_calendar_id")
     }
 }

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

@@ -31,7 +31,6 @@ import androidx.compose.material.icons.filled.Add
 import androidx.compose.material.icons.filled.CalendarMonth
 import androidx.compose.material.icons.filled.Close
 import androidx.compose.material.icons.filled.Delete
-import androidx.compose.material.icons.filled.Edit
 import androidx.compose.material.icons.filled.FileDownload
 import androidx.compose.material.icons.filled.OpenInNew
 import androidx.compose.material.icons.filled.Palette
@@ -46,6 +45,7 @@ import androidx.compose.material3.Scaffold
 import androidx.compose.material3.SnackbarHost
 import androidx.compose.material3.SnackbarHostState
 import androidx.compose.material3.Surface
+import androidx.compose.material3.Switch
 import androidx.compose.material3.Text
 import androidx.compose.material3.TextButton
 import androidx.compose.material3.TopAppBar
@@ -59,11 +59,14 @@ import androidx.compose.runtime.saveable.rememberSaveable
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.draw.alpha
 import androidx.compose.ui.draw.clip
 import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.graphics.vector.ImageVector
 import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.semantics.contentDescription
+import androidx.compose.ui.semantics.semantics
 import androidx.compose.ui.text.font.FontWeight
 import androidx.compose.ui.text.input.KeyboardCapitalization
 import androidx.compose.ui.unit.dp
@@ -98,6 +101,7 @@ fun CalendarsScreen(
     viewModel: CalendarsViewModel = hiltViewModel(),
 ) {
     val calendars by viewModel.calendars.collectAsStateWithLifecycle()
+    val disabledIds by viewModel.disabledCalendarIds.collectAsStateWithLifecycle()
     val error by viewModel.error.collectAsStateWithLifecycle()
     val backupResult by viewModel.backupResult.collectAsStateWithLifecycle()
 
@@ -134,6 +138,7 @@ fun CalendarsScreen(
         CalendarsList(
             local = calendars.filter { it.isLocal },
             synced = calendars.filterNot { it.isLocal },
+            disabledIds = disabledIds,
             error = error,
             onConsumeError = viewModel::consumeError,
             backupResult = backupResult,
@@ -142,6 +147,7 @@ fun CalendarsScreen(
             onBack = onBack,
             onAdd = { editorSession++; editorId = NEW_CALENDAR_ID },
             onEdit = { calendar -> editorSession++; editorId = calendar.id },
+            onSetDisabled = viewModel::setDisabled,
         )
     }
 }
@@ -150,6 +156,7 @@ fun CalendarsScreen(
 private fun CalendarsList(
     local: List<CalendarSource>,
     synced: List<CalendarSource>,
+    disabledIds: Set<Long>,
     error: Boolean,
     onConsumeError: () -> Unit,
     backupResult: BackupResult?,
@@ -158,6 +165,7 @@ private fun CalendarsList(
     onBack: () -> Unit,
     onAdd: () -> Unit,
     onEdit: (CalendarSource) -> Unit,
+    onSetDisabled: (Long, Boolean) -> Unit,
 ) {
     val context = LocalContext.current
     val snackbarHostState = remember { SnackbarHostState() }
@@ -206,19 +214,21 @@ private fun CalendarsList(
         if (local.isEmpty()) {
             HintText(stringResource(R.string.calendars_local_empty))
         }
+        HintText(stringResource(R.string.calendars_disable_hint))
         val localCount = local.size + 1
         local.forEachIndexed { index, calendar ->
+            val disabled = calendar.id in disabledIds
             GroupedRow(
                 title = calendar.displayName,
                 summary = calendar.description,
                 position = positionOf(index, localCount),
-                leading = { CalendarColorChip(calendar.color) },
+                dimmed = disabled,
+                leading = { CalendarColorChip(calendar.color, dimIf(disabled)) },
                 trailing = {
-                    Icon(
-                        Icons.Default.Edit,
-                        contentDescription = stringResource(R.string.calendars_edit_title),
-                        tint = MaterialTheme.colorScheme.onSurfaceVariant,
-                        modifier = Modifier.size(20.dp),
+                    EnableSwitch(
+                        calendarName = calendar.displayName,
+                        enabled = !disabled,
+                        onToggle = { enabled -> onSetDisabled(calendar.id, !enabled) },
                     )
                 },
                 onClick = { onEdit(calendar) },
@@ -258,10 +268,19 @@ private fun CalendarsList(
             .forEach { (account, cals) ->
                 AccountHeader(account = account, accountType = cals.first().accountType)
                 cals.forEachIndexed { index, calendar ->
+                    val disabled = calendar.id in disabledIds
                     GroupedRow(
                         title = calendar.displayName,
                         position = positionOf(index, cals.size),
-                        leading = { CalendarColorChip(calendar.color) },
+                        dimmed = disabled,
+                        leading = { CalendarColorChip(calendar.color, dimIf(disabled)) },
+                        trailing = {
+                            EnableSwitch(
+                                calendarName = calendar.displayName,
+                                enabled = !disabled,
+                                onToggle = { enabled -> onSetDisabled(calendar.id, !enabled) },
+                            )
+                        },
                     )
                 }
             }
@@ -425,6 +444,30 @@ private fun CalendarEditor(
     }
 }
 
+/**
+ * The per-row enable/disable control. Checked = the calendar is shown in the
+ * app; unchecking disables it (events, filters and pickers all drop it) without
+ * touching any provider data. Carries its own content description so the toggle
+ * is self-describing to screen readers even on a dimmed row.
+ */
+@Composable
+private fun EnableSwitch(
+    calendarName: String,
+    enabled: Boolean,
+    onToggle: (Boolean) -> Unit,
+) {
+    val label = stringResource(R.string.calendars_show_in_app_a11y, calendarName)
+    Switch(
+        checked = enabled,
+        onCheckedChange = onToggle,
+        modifier = Modifier.semantics { contentDescription = label },
+    )
+}
+
+/** Fade a leading element to the M3 disabled emphasis when [disabled]. */
+private fun dimIf(disabled: Boolean): Modifier =
+    if (disabled) Modifier.alpha(0.38f) else Modifier
+
 /** Tonal field card matching the event editor's design (icon + content). */
 @Composable
 private fun EditorCard(

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

@@ -7,6 +7,7 @@ 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.ics.IcsExporter
+import de.jeanlucmakiola.calendula.data.prefs.CalendarPrefs
 import de.jeanlucmakiola.calendula.domain.CalendarSource
 import de.jeanlucmakiola.calendula.domain.ics.IcsWriter
 import kotlinx.coroutines.CoroutineDispatcher
@@ -15,6 +16,7 @@ import kotlinx.coroutines.flow.SharingStarted
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.asStateFlow
 import kotlinx.coroutines.flow.catch
+import kotlinx.coroutines.flow.first
 import kotlinx.coroutines.flow.flowOn
 import kotlinx.coroutines.flow.stateIn
 import kotlinx.coroutines.launch
@@ -33,6 +35,7 @@ import javax.inject.Inject
 class CalendarsViewModel @Inject constructor(
     private val repository: CalendarRepository,
     private val icsExporter: IcsExporter,
+    private val prefs: CalendarPrefs,
     @IoDispatcher private val io: CoroutineDispatcher,
 ) : ViewModel() {
 
@@ -46,6 +49,20 @@ class CalendarsViewModel @Inject constructor(
                 initialValue = emptyList(),
             )
 
+    /**
+     * Calendars the user has disabled in the app. This screen is the only
+     * surface that lists them, so it both reads the set (to dim the rows) and
+     * toggles it. Every other surface simply excludes these ids.
+     */
+    val disabledCalendarIds: StateFlow<Set<Long>> =
+        prefs.disabledCalendarIds
+            .flowOn(io)
+            .stateIn(
+                scope = viewModelScope,
+                started = SharingStarted.WhileSubscribed(5_000L),
+                initialValue = emptySet(),
+            )
+
     private val _error = MutableStateFlow(false)
     val error: StateFlow<Boolean> = _error.asStateFlow()
 
@@ -93,6 +110,19 @@ class CalendarsViewModel @Inject constructor(
         repository.deleteCalendar(id)
     }
 
+    /**
+     * Enable or disable a calendar app-side. Disabling removes it from every
+     * surface but Settings → Calendars (and hides its events) without touching
+     * provider data — purely a reversible Calendula-local view choice.
+     */
+    fun setDisabled(id: Long, disabled: Boolean) {
+        viewModelScope.launch {
+            val current = prefs.disabledCalendarIds.first()
+            val next = if (disabled) current + id else current - id
+            if (next != current) prefs.setDisabledCalendarIds(next)
+        }
+    }
+
     private inline fun write(crossinline block: suspend () -> Unit) {
         viewModelScope.launch {
             try {

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

@@ -128,7 +128,9 @@ fun CollapsingScaffold(
  * One row in a grouped list: an M3 [ListItem] over a tonal [Surface] whose
  * corner radii come from its [position] (so a run of rows reads as a single
  * rounded card). Corners round further on press. A null [onClick] makes the
- * row non-interactive (e.g. read-only entries).
+ * row non-interactive (e.g. read-only entries). [dimmed] fades the headline and
+ * summary to the M3 disabled emphasis while leaving the [trailing] control at
+ * full opacity — for rows that are present but switched off.
  */
 @OptIn(ExperimentalMaterial3Api::class)
 @Composable
@@ -138,6 +140,7 @@ fun GroupedRow(
     modifier: Modifier = Modifier,
     summary: String? = null,
     selected: Boolean = false,
+    dimmed: Boolean = false,
     minHeight: Dp = 72.dp,
     leading: @Composable (() -> Unit)? = null,
     trailing: @Composable (() -> Unit)? = null,
@@ -169,6 +172,16 @@ fun GroupedRow(
             supportingColor = MaterialTheme.colorScheme.onSecondaryContainer,
             trailingIconColor = MaterialTheme.colorScheme.onSecondaryContainer,
         )
+    } else if (dimmed) {
+        // M3 disabled emphasis (0.38α) on the text/leading; the trailing control
+        // stays full-opacity so the toggle reads as live even on a faded row.
+        val muted = MaterialTheme.colorScheme.onSurface.copy(alpha = 0.38f)
+        ListItemDefaults.colors(
+            containerColor = Color.Transparent,
+            headlineColor = muted,
+            leadingIconColor = muted,
+            supportingColor = muted,
+        )
     } else {
         ListItemDefaults.colors(containerColor = Color.Transparent)
     }

app/src/main/java/de/jeanlucmakiola/calendula/ui/edit/EventEditViewModel.kt

@@ -121,10 +121,18 @@ class EventEditViewModel @Inject constructor(
         val allowColorOnUnsupported: Boolean,
     )
 
-    /** Writable calendars — the only valid event targets. */
-    private val writableCalendars: Flow<List<CalendarSource>> = repository.calendars()
-        .map { calendars -> calendars.filter { it.canModifyContents } }
-        .catch { emit(emptyList()) }
+    /**
+     * Writable calendars — the only valid event targets. Disabled calendars are
+     * excluded, so you can't create into a calendar you've removed from the app;
+     * a last-used preselect landing on a now-disabled calendar falls back to the
+     * first remaining writable one (handled by [resolvedCalendarId] and [state]).
+     */
+    private val writableCalendars: Flow<List<CalendarSource>> = combine(
+        repository.calendars(),
+        prefs.disabledCalendarIds,
+    ) { calendars, disabled ->
+        calendars.filter { it.canModifyContents && it.id !in disabled }
+    }.catch { emit(emptyList()) }
 
     /** The target calendar id, resolved exactly as the form shows it. */
     private val resolvedCalendarId: Flow<Long?> = combine(

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

@@ -30,11 +30,16 @@ class FilterViewModel @Inject constructor(
         combine(
             repository.calendars(),
             prefs.hiddenCalendarIds,
-        ) { calendars, hidden ->
-            if (calendars.isEmpty()) {
+            prefs.disabledCalendarIds,
+        ) { calendars, hidden, disabled ->
+            // Disabled calendars are gone from the app entirely — they don't
+            // belong in the drawer's hide/show list (you can't hide what's
+            // already disabled). They live only in Settings → Calendars.
+            val enabled = calendars.filterNot { it.id in disabled }
+            if (enabled.isEmpty()) {
                 FilterUiState.Failure(FailureReason.NoCalendarsConfigured)
             } else {
-                FilterUiState.Success(groupByAccount(calendars, hidden))
+                FilterUiState.Success(groupByAccount(enabled, hidden))
             }
         }
             .catch { emit(FilterUiState.Failure(FailureReason.ProviderUnavailable)) }

app/src/main/java/de/jeanlucmakiola/calendula/ui/imports/ImportViewModel.kt

@@ -7,6 +7,7 @@ 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.ics.IcsImporter
+import de.jeanlucmakiola.calendula.data.prefs.CalendarPrefs
 import de.jeanlucmakiola.calendula.domain.CalendarSource
 import de.jeanlucmakiola.calendula.domain.EventForm
 import de.jeanlucmakiola.calendula.domain.ics.IcsImportSummary
@@ -56,6 +57,7 @@ sealed interface ImportUiState {
 class ImportViewModel @Inject constructor(
     private val repository: CalendarRepository,
     private val importer: IcsImporter,
+    private val prefs: CalendarPrefs,
     @IoDispatcher private val io: CoroutineDispatcher,
 ) : ViewModel() {
 
@@ -79,11 +81,17 @@ class ImportViewModel @Inject constructor(
                     form = parsed.events.single().toEventForm(TimeZone.currentSystemDefault()),
                     warnings = parsed.warnings,
                 )
-                else -> ImportUiState.Many(
-                    events = parsed.events,
-                    warnings = parsed.warnings,
-                    calendars = repository.calendars().first().filter { it.canModifyContents },
-                )
+                else -> {
+                    // A disabled calendar is removed from the app, so it can't be
+                    // an import target — exclude it alongside the read-only ones.
+                    val disabled = prefs.disabledCalendarIds.first()
+                    ImportUiState.Many(
+                        events = parsed.events,
+                        warnings = parsed.warnings,
+                        calendars = repository.calendars().first()
+                            .filter { it.canModifyContents && it.id !in disabled },
+                    )
+                }
             }
         }
     }

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

@@ -317,6 +317,8 @@
     <string name="calendars_local_header">Your calendars</string>
     <string name="calendars_local_empty">No local calendars yet. Create one to keep events on this device only.</string>
     <string name="calendars_add">Add calendar</string>
+    <string name="calendars_disable_hint">Turn a calendar off to remove it from the app — its events, filters and pickers. Nothing is deleted, and you can turn it back on here anytime.</string>
+    <string name="calendars_show_in_app_a11y">Show \"%1$s\" in the app</string>
     <string name="calendars_synced_header">Synced calendars</string>
     <string name="calendars_synced_hint">These come from accounts on your device. Create and edit them in their own app.</string>
     <string name="calendars_manage_in_app">Manage</string>

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

@@ -170,6 +170,74 @@ class CalendarRepositoryImplTest {
         }
     }
 
+    @Test
+    fun `instances drops events whose calendar the user disabled`(@TempDir tempDir: Path) = runTest {
+        val prefs = newPrefs(tempDir)
+        prefs.setDisabledCalendarIds(setOf(2L))
+        val fake = FakeCalendarDataSource().apply {
+            instancesResult = { _, _ ->
+                listOf(
+                    makeEvent(10L, "Enabled", calendarId = 1L),
+                    makeEvent(11L, "Disabled", calendarId = 2L),
+                )
+            }
+        }
+        val repo = CalendarRepositoryImpl(fake, prefs, newSettings(tempDir), UnconfinedTestDispatcher(testScheduler))
+
+        val range = Instant.fromEpochMilliseconds(0)..Instant.fromEpochMilliseconds(10_000L)
+        repo.instances(range).test {
+            assertThat(awaitItem().map { it.title }).containsExactly("Enabled")
+            cancelAndIgnoreRemainingEvents()
+        }
+    }
+
+    @Test
+    fun `instances applies the union of hidden and disabled sets`(@TempDir tempDir: Path) = runTest {
+        val prefs = newPrefs(tempDir)
+        prefs.setHiddenCalendarIds(setOf(2L))
+        prefs.setDisabledCalendarIds(setOf(3L))
+        val fake = FakeCalendarDataSource().apply {
+            instancesResult = { _, _ ->
+                listOf(
+                    makeEvent(10L, "Shown", calendarId = 1L),
+                    makeEvent(11L, "Hidden", calendarId = 2L),
+                    makeEvent(12L, "Disabled", calendarId = 3L),
+                )
+            }
+        }
+        val repo = CalendarRepositoryImpl(fake, prefs, newSettings(tempDir), UnconfinedTestDispatcher(testScheduler))
+
+        val range = Instant.fromEpochMilliseconds(0)..Instant.fromEpochMilliseconds(10_000L)
+        repo.instances(range).test {
+            assertThat(awaitItem().map { it.title }).containsExactly("Shown")
+            cancelAndIgnoreRemainingEvents()
+        }
+    }
+
+    @Test
+    fun `instances re-emits when the disabled 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, newSettings(tempDir), 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.setDisabledCalendarIds(setOf(2L))
+
+            assertThat(awaitItem().map { it.title }).containsExactly("A")
+            cancelAndIgnoreRemainingEvents()
+        }
+    }
+
     @Test
     fun `createEvent delegates and returns the new id`(@TempDir tempDir: Path) = runTest {
         val fake = FakeCalendarDataSource().apply { nextInsertId = 77L }

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

@@ -50,4 +50,34 @@ class CalendarPrefsTest {
         }
         assertThat(prefs.hiddenCalendarIds.first()).isEqualTo(setOf(1L, 3L))
     }
+
+    @Test
+    fun `disabledCalendarIds defaults to empty when unset`(@TempDir tempDir: Path) = runTest {
+        val prefs = CalendarPrefs(newDataStore(tempDir))
+        assertThat(prefs.disabledCalendarIds.first()).isEmpty()
+    }
+
+    @Test
+    fun `setDisabledCalendarIds round-trips through DataStore`(@TempDir tempDir: Path) = runTest {
+        val prefs = CalendarPrefs(newDataStore(tempDir))
+        prefs.setDisabledCalendarIds(setOf(1L, 42L, 7L))
+        assertThat(prefs.disabledCalendarIds.first()).isEqualTo(setOf(1L, 42L, 7L))
+    }
+
+    @Test
+    fun `setting empty disabled set clears storage`(@TempDir tempDir: Path) = runTest {
+        val prefs = CalendarPrefs(newDataStore(tempDir))
+        prefs.setDisabledCalendarIds(setOf(1L))
+        prefs.setDisabledCalendarIds(emptySet())
+        assertThat(prefs.disabledCalendarIds.first()).isEmpty()
+    }
+
+    @Test
+    fun `hidden and disabled sets are stored independently`(@TempDir tempDir: Path) = runTest {
+        val prefs = CalendarPrefs(newDataStore(tempDir))
+        prefs.setHiddenCalendarIds(setOf(1L))
+        prefs.setDisabledCalendarIds(setOf(2L))
+        assertThat(prefs.hiddenCalendarIds.first()).isEqualTo(setOf(1L))
+        assertThat(prefs.disabledCalendarIds.first()).isEqualTo(setOf(2L))
+    }
 }