Avoid sync "operation" when talking about checkpoints

packages/powersync_core/lib/src/database/powersync_db_mixin.dart

@@ -159,13 +159,14 @@ mixin PowerSyncDatabaseMixin implements SqliteConnection {
     }
   }
 
-  /// Returns a [Future] which will resolve once a synchronization operation has
-  /// completed.
+  /// Returns a [Future] which will resolve once at least one full sync cycle
+  /// has completed (meaninng that the first consistent checkpoint has been
+  /// reached across all buckets).
   ///
-  /// When [priority] is null (the default), this method waits for a full sync
-  /// operation to complete. When set to a [BucketPriority] however, it also
-  /// completes once a partial sync operation containing that priority has
-  /// completed.
+  /// When [priority] is null (the default), this method waits for the first
+  /// full sync checkpoint to complete. When set to a [BucketPriority] however,
+  /// it completes once all buckets within that priority (as well as those in
+  /// higher priorities) have been synchronized at least once.
   Future<void> waitForFirstSync({BucketPriority? priority}) async {
     bool matches(SyncStatus status) {
       if (priority == null) {

packages/powersync_core/lib/src/sync_status.dart

@@ -97,12 +97,15 @@ final class SyncStatus {
     return downloadError ?? uploadError;
   }
 
-  /// Returns [lastSyncedAt] and [hasSynced] information for a partial sync
-  /// operation, or `null` if the status for that priority is unknown.
+  /// Returns information for [lastSyncedAt] and [hasSynced] information at a
+  /// partial sync priority, or `null` if the status for that priority is
+  /// unknown.
   ///
   /// The information returned may be more generic than requested. For instance,
-  /// a completed sync operation (as expressed by [lastSyncedAt]) also
-  /// guarantees that every bucket priority was synchronized before that.
+  /// a fully-completed sync cycle (as expressed by [lastSyncedAt]) necessarily
+  /// includes all buckets across all priorities. So, if no further partial
+  /// checkpoints have been received since that complete sync,
+  /// [statusForPriority] may return information for that complete sync.
   /// Similarly, requesting the sync status for priority `1` may return
   /// information extracted from the lower priority `2` since each partial sync
   /// in priority `2` necessarily includes a consistent view over data in