From 54c772023b6b8c668fc3303e7cc1f67e26529d5a Mon Sep 17 00:00:00 2001
From: pinpong <o.nitzschke@gmail.com>
Date: Sun, 11 Oct 2026 18:00:55 +0700
Subject: [PATCH] Fix onViewableItemsChanged not firing after
 StrictMode/Activity remount

---
 .../Lists/ViewabilityHelper.js                |  1 +
 .../Lists/__tests__/ViewabilityHelper-test.js | 82 +++++++++++++++++++
 2 files changed, 83 insertions(+)

diff --git a/packages/virtualized-lists/Lists/ViewabilityHelper.js b/packages/virtualized-lists/Lists/ViewabilityHelper.js
index 5fc5addc11b8..35b929e5851f 100644
--- a/packages/virtualized-lists/Lists/ViewabilityHelper.js
+++ b/packages/virtualized-lists/Lists/ViewabilityHelper.js
@@ -99,6 +99,7 @@ class ViewabilityHelper {
    */
   dispose() {
     this._timers.forEach(clearTimeout);
+    this.resetViewableIndices();
   }
 
   /**
diff --git a/packages/virtualized-lists/Lists/__tests__/ViewabilityHelper-test.js b/packages/virtualized-lists/Lists/__tests__/ViewabilityHelper-test.js
index fb2c672826e4..a0e9051464ec 100644
--- a/packages/virtualized-lists/Lists/__tests__/ViewabilityHelper-test.js
+++ b/packages/virtualized-lists/Lists/__tests__/ViewabilityHelper-test.js
@@ -767,6 +767,88 @@ describe('onUpdate', function () {
     });
   });
 
+  it('minimumViewTime reports items again after dispose', function () {
+    const helper = new ViewabilityHelper({
+      minimumViewTime: 350,
+      viewAreaCoveragePercentThreshold: 0,
+    });
+    rowFrames = {
+      a: {y: 0, height: 200},
+      b: {y: 200, height: 200},
+    };
+    data = [{key: 'a'}, {key: 'b'}];
+    const onViewableItemsChanged = jest.fn();
+    helper.onUpdate(
+      props,
+      0,
+      200,
+      // $FlowFixMe[incompatible-type] - Invalid `ListMetricsAggregator`.
+      {getCellMetrics},
+      createViewToken,
+      onViewableItemsChanged,
+    );
+    // Cancels the pending callback, e.g. when the list gets hidden.
+    helper.dispose();
+    jest.runAllTimers();
+    expect(onViewableItemsChanged).not.toBeCalled();
+
+    helper.onUpdate(
+      props,
+      0,
+      200,
+      // $FlowFixMe[incompatible-type] - Invalid `ListMetricsAggregator`.
+      {getCellMetrics},
+      createViewToken,
+      onViewableItemsChanged,
+    );
+    jest.runAllTimers();
+
+    expect(onViewableItemsChanged.mock.calls.length).toBe(1);
+    expect(onViewableItemsChanged.mock.calls[0][0]).toEqual({
+      changed: [{isViewable: true, key: 'a'}],
+      viewabilityConfig: {
+        minimumViewTime: 350,
+        viewAreaCoveragePercentThreshold: 0,
+      },
+      viewableItems: [{isViewable: true, key: 'a'}],
+    });
+  });
+
+  it('does not report already viewable items again after dispose', function () {
+    const helper = new ViewabilityHelper({
+      viewAreaCoveragePercentThreshold: 0,
+    });
+    rowFrames = {
+      a: {y: 0, height: 200},
+      b: {y: 200, height: 200},
+    };
+    data = [{key: 'a'}, {key: 'b'}];
+    const onViewableItemsChanged = jest.fn();
+    helper.onUpdate(
+      props,
+      0,
+      200,
+      // $FlowFixMe[incompatible-type] - Invalid `ListMetricsAggregator`.
+      {getCellMetrics},
+      createViewToken,
+      onViewableItemsChanged,
+    );
+    expect(onViewableItemsChanged.mock.calls.length).toBe(1);
+
+    helper.dispose();
+    helper.onUpdate(
+      props,
+      0,
+      200,
+      // $FlowFixMe[incompatible-type] - Invalid `ListMetricsAggregator`.
+      {getCellMetrics},
+      createViewToken,
+      onViewableItemsChanged,
+    );
+
+    expect(onViewableItemsChanged.mock.calls.length).toBe(1);
+  });
+
   it('waitForInteraction blocks callback until interaction', function () {
     const helper = new ViewabilityHelper({
       waitForInteraction: true,