Code review:

- @Volatile ScheduledPostNotifier.channel: two workers firing in the
  same window can race on ensureChannel from different IO threads.
  createNotificationChannel is idempotent, but the field write needs a
  visibility fence so both threads see the cached reference.
- @Volatile PoolEventOutbox.eventOutbox map ref + PoolEventOutboxState
  .relaysRemaining set ref. The new pendingPublishRelaysFor polling
  path reads these from the WorkManager IO thread; mutations still
  happen on NostrClient's IO scope. Pre-existing visibility gap that
  this poll surface exposed; @Volatile is the minimal fix.
- ScheduledPostsScreen.SectionLabel: read the locale from
  LocalConfiguration.current.locales[0] (the Compose-resolved locale)
  rather than Locale.getDefault() (the system locale, which can drift
  from app config and breaks Turkish I/i casing).

amethyst/src/main/java/com/vitorpamplona/amethyst/service/scheduledposts/ScheduledPostNotifier.kt

@@ -39,6 +39,10 @@ import com.vitorpamplona.amethyst.ui.stringRes
  * now guards against; the notification closes the loop.
  */
 object ScheduledPostNotifier {
+    // @Volatile so the channel reference is visible across the WorkManager IO
+    // thread pool — two workers firing in the same window can race on
+    // ensureChannel. createNotificationChannel itself is idempotent.
+    @Volatile
     private var channel: NotificationChannel? = null
     private const val SCHEDULED_POST_NOT_ID_BASE = 0x70000
 

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/scheduledposts/ScheduledPostsScreen.kt

@@ -78,6 +78,7 @@ import androidx.compose.ui.graphics.Brush
 import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.graphics.compositeOver
 import androidx.compose.ui.platform.LocalClipboardManager
+import androidx.compose.ui.platform.LocalConfiguration
 import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.res.pluralStringResource
 import androidx.compose.ui.semantics.semantics
@@ -111,7 +112,6 @@ import java.time.LocalDate
 import java.time.ZoneId
 import java.time.format.DateTimeFormatter
 import java.time.format.FormatStyle
-import java.util.Locale
 
 @OptIn(ExperimentalMaterial3Api::class, ExperimentalFoundationApi::class)
 @Composable
@@ -460,8 +460,9 @@ private fun ScheduledPostCardExpandedPanel(
 
 @Composable
 private fun SectionLabel(text: String) {
+    val locale = LocalConfiguration.current.locales[0]
     Text(
-        text = text.uppercase(Locale.getDefault()),
+        text = text.uppercase(locale),
         style = MaterialTheme.typography.labelSmall,
         color = MaterialTheme.colorScheme.onSurfaceVariant,
         modifier = Modifier.padding(bottom = 4.dp),