Debounce drift table updates

This can be a problem during the very first sync, where all exercises, units,
ingredients are loaded and rebuild on every new data point.

Author: rolandgeider

lib/providers/exercise_repository.dart

@@ -165,6 +165,7 @@ class ExerciseRepository {
 
     late StreamController<ExerciseState> controller;
     final subs = <StreamSubscription>[];
+    Timer? emitTimer;
 
     void emit() {
       if (exerciseRows == null ||
@@ -303,14 +304,22 @@ class ExerciseRepository {
       controller.add(ExerciseState(exercises));
     }
 
+    // A full rebuild runs on every table update. During the initial sync many
+    // updates arrive in bursts, so coalesce them into a single rebuild once
+    // they settle instead of reassembling the whole catalog hundreds of times.
+    void scheduleEmit() {
+      emitTimer?.cancel();
+      emitTimer = Timer(const Duration(milliseconds: 200), emit);
+    }
+
     controller = StreamController<ExerciseState>(
       onListen: () {
         void addSub<T>(Stream<T> source, void Function(T) assign) {
           subs.add(
             source.listen(
               (value) {
                 assign(value);
-                emit();
+                scheduleEmit();
               },
               onError: controller.addError,
             ),
@@ -334,6 +343,7 @@ class ExerciseRepository {
         addSub(_db.select(_db.exerciseCommentTable).watch(), (v) => comments = v);
       },
       onCancel: () async {
+        emitTimer?.cancel();
         for (final s in subs) {
           await s.cancel();
         }

lib/providers/nutrition_repository.dart

@@ -20,6 +20,7 @@ import 'package:collection/collection.dart';
 import 'package:drift/drift.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:logging/logging.dart';
+import 'package:stream_transform/stream_transform.dart';
 import 'package:wger/database/powersync/database.dart';
 import 'package:wger/models/nutrition/ingredient.dart';
 import 'package:wger/models/nutrition/ingredient_weight_unit.dart';
@@ -40,6 +41,10 @@ class NutritionRepository {
 
   NutritionRepository(this._db);
 
+  /// Coalesces bursts of Drift table updates (e.g. during the initial sync) so
+  /// the heavy per-emission hydration runs once they settle, not on every write.
+  static const _hydrationDebounce = Duration(milliseconds: 200);
+
   // --- Plans ---
 
   /// Streams all nutritional plans from the local PowerSync-backed Drift table.
@@ -113,7 +118,7 @@ class NutritionRepository {
           OrderingTerm.asc(_db.mealTable.time),
         ]);
 
-    return query.watch().map(_hydrateMeals);
+    return query.watch().debounce(_hydrationDebounce).map(_hydrateMeals);
   }
 
   /// Collapses cross-joined rows into hydrated [Meal]s with their child items.
@@ -268,7 +273,7 @@ class NutritionRepository {
       ),
     ])..orderBy([OrderingTerm(expression: _db.logItemTable.datetime)]);
 
-    return query.watch().map(_hydrateLogs);
+    return query.watch().debounce(_hydrationDebounce).map(_hydrateLogs);
   }
 
   /// Collapses the cross-joined rows into hydrated [LogItem]s.