Add batch and untracked utility functions

Author: medz

packages/solidart/lib/src/v3.dart

@@ -41,6 +41,24 @@ final class SolidartConfig {
   static bool trackPreviousValue = true;
 }
 
+T untracked<T>(T Function() callback) {
+  final prevSub = preset.setActiveSub();
+  try {
+    return callback();
+  } finally {
+    preset.setActiveSub(prevSub);
+  }
+}
+
+T batch<T>(T Function() fn) {
+  preset.startBatch();
+  try {
+    return fn();
+  } finally {
+    preset.endBatch();
+  }
+}
+
 class Identifier {
   Identifier._(this.name) : value = _counter++;
   static int _counter = 0;

packages/solidart/lib/v3.dart

@@ -1,4 +1,12 @@
 // TODO(medz): rename the v3.dart to solidart.dart filename.
 
 export 'src/v3.dart'
-    show Computed, Effect, LazySignal, ReadonlySignal, Signal, SolidartConfig;
+    show
+        Computed,
+        Effect,
+        LazySignal,
+        ReadonlySignal,
+        Signal,
+        SolidartConfig,
+        batch,
+        untracked;

packages/solidart/test/v3_batch_test.dart

@@ -0,0 +1,31 @@
+import 'package:solidart/v3.dart';
+import 'package:test/test.dart';
+
+void main() {
+  test('batch groups updates and flushes once', () {
+    final x = Signal(10);
+    final y = Signal(20);
+    final total = Signal(30);
+
+    final calls = <({int x, int y, int total})>[];
+
+    Effect(() {
+      calls.add((x: x.value, y: y.value, total: total.value));
+    });
+
+    expect(calls, [
+      (x: 10, y: 20, total: 30),
+    ]);
+
+    batch(() {
+      x.value++;
+      y.value++;
+      total.value = x.value + y.value;
+    });
+
+    expect(calls, [
+      (x: 10, y: 20, total: 30),
+      (x: 11, y: 21, total: 32),
+    ]);
+  });
+}

packages/solidart/test/v3_untracked_test.dart

@@ -0,0 +1,28 @@
+import 'package:solidart/v3.dart';
+import 'package:test/test.dart';
+
+void main() {
+  test('untracked prevents dependency tracking', () {
+    final count = Signal(0);
+    final effectCount = Signal(0);
+    var runs = 0;
+
+    Effect(() {
+      count.value;
+      runs++;
+      effectCount.value = untracked(() => effectCount.value + 1);
+    });
+
+    expect(runs, 1);
+    expect(effectCount.value, 1);
+
+    count.value = 1;
+
+    expect(runs, 2);
+    expect(effectCount.value, 2);
+
+    effectCount.value = 3;
+
+    expect(runs, 2);
+  });
+}