From ff191f24b5f49252672ac4d3c46ef1e79cf7290d Mon Sep 17 00:00:00 2001
From: "Sebastian \"Sebbie\" Silbermann" <sebastian.silbermann@vercel.com>
Date: Wed, 28 Jan 2026 11:54:50 +0100
Subject: [PATCH 1/2] [Perf Tracks] Handle arrays with bigints in deep objects
 (#35648)

---
 .../__tests__/ReactPerformanceTrack-test.js   | 83 +++++++++++++++++++
 .../shared/ReactPerformanceTrackProperties.js |  4 +-
 2 files changed, 86 insertions(+), 1 deletion(-)

diff --git a/packages/react-reconciler/src/__tests__/ReactPerformanceTrack-test.js b/packages/react-reconciler/src/__tests__/ReactPerformanceTrack-test.js
index 0f5152e8d47..703a69469c6 100644
--- a/packages/react-reconciler/src/__tests__/ReactPerformanceTrack-test.js
+++ b/packages/react-reconciler/src/__tests__/ReactPerformanceTrack-test.js
@@ -440,4 +440,87 @@ describe('ReactPerformanceTracks', () => {
     ]);
     performanceMeasureCalls.length = 0;
   });
+
+  // @gate __DEV__ && enableComponentPerformanceTrack
+  it('can handle bigint in arrays', async () => {
+    const App = function App({numbers}) {
+      Scheduler.unstable_advanceTime(10);
+      React.useEffect(() => {}, [numbers]);
+    };
+
+    Scheduler.unstable_advanceTime(1);
+    await act(() => {
+      ReactNoop.render(
+        <App
+          data={{
+            deeply: {
+              nested: {
+                numbers: [1n],
+              },
+            },
+          }}
+        />,
+      );
+    });
+
+    expect(performanceMeasureCalls).toEqual([
+      [
+        'Mount',
+        {
+          detail: {
+            devtools: {
+              color: 'warning',
+              properties: null,
+              tooltipText: 'Mount',
+              track: 'Components ⚛',
+            },
+          },
+          end: 11,
+          start: 1,
+        },
+      ],
+    ]);
+    performanceMeasureCalls.length = 0;
+
+    Scheduler.unstable_advanceTime(10);
+
+    await act(() => {
+      ReactNoop.render(
+        <App
+          data={{
+            deeply: {
+              nested: {
+                numbers: [2n],
+              },
+            },
+          }}
+        />,
+      );
+    });
+
+    expect(performanceMeasureCalls).toEqual([
+      [
+        '​App',
+        {
+          detail: {
+            devtools: {
+              color: 'primary-dark',
+              properties: [
+                ['Changed Props', ''],
+                ['  data', ''],
+                ['    deeply', ''],
+                ['      nested', ''],
+                ['–       numbers', 'Array'],
+                ['+       numbers', 'Array'],
+              ],
+              tooltipText: 'App',
+              track: 'Components ⚛',
+            },
+          },
+          end: 31,
+          start: 21,
+        },
+      ],
+    ]);
+  });
 });
diff --git a/packages/shared/ReactPerformanceTrackProperties.js b/packages/shared/ReactPerformanceTrackProperties.js
index 87231c20c49..f088d51025b 100644
--- a/packages/shared/ReactPerformanceTrackProperties.js
+++ b/packages/shared/ReactPerformanceTrackProperties.js
@@ -16,7 +16,7 @@ import getComponentNameFromType from './getComponentNameFromType';
 
 const EMPTY_ARRAY = 0;
 const COMPLEX_ARRAY = 1;
-const PRIMITIVE_ARRAY = 2; // Primitive values only
+const PRIMITIVE_ARRAY = 2; // Primitive values only that are accepted by JSON.stringify
 const ENTRIES_ARRAY = 3; // Tuple arrays of string and value (like Headers, Map, etc)
 
 // Showing wider objects in the devtools is not useful.
@@ -46,6 +46,8 @@ function getArrayKind(array: Object): 0 | 1 | 2 | 3 {
       return COMPLEX_ARRAY;
     } else if (kind !== EMPTY_ARRAY && kind !== PRIMITIVE_ARRAY) {
       return COMPLEX_ARRAY;
+    } else if (typeof value === 'bigint') {
+      return COMPLEX_ARRAY;
     } else {
       kind = PRIMITIVE_ARRAY;
     }

From 87ae75b33f71eb673c55ddb3a147a9e58b7d05bd Mon Sep 17 00:00:00 2001
From: "Sebastian \"Sebbie\" Silbermann" <sebastian.silbermann@vercel.com>
Date: Wed, 28 Jan 2026 12:14:59 +0100
Subject: [PATCH 2/2] [Perf Tracks] Use minus (`-`) instead of en dash for
 removed props (#35649)

---
 .../src/__tests__/ReactPerformanceTrack-test.js             | 6 +++---
 packages/shared/ReactPerformanceTrackProperties.js          | 2 +-
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/packages/react-reconciler/src/__tests__/ReactPerformanceTrack-test.js b/packages/react-reconciler/src/__tests__/ReactPerformanceTrack-test.js
index 703a69469c6..faaadb9cb61 100644
--- a/packages/react-reconciler/src/__tests__/ReactPerformanceTrack-test.js
+++ b/packages/react-reconciler/src/__tests__/ReactPerformanceTrack-test.js
@@ -231,7 +231,7 @@ describe('ReactPerformanceTracks', () => {
               properties: [
                 ['Changed Props', ''],
                 ['  data', ''],
-                ['–   buffer', 'null'],
+                ['-   buffer', 'null'],
                 ['+   buffer', 'Uint8Array'],
                 ['+     0', '0'],
                 ['+     1', '0'],
@@ -422,7 +422,7 @@ describe('ReactPerformanceTracks', () => {
               color: 'error',
               properties: [
                 ['Changed Props', ''],
-                ['– value', '1'],
+                ['- value', '1'],
                 ['+ value', '2'],
               ],
               tooltipText: 'Left',
@@ -510,7 +510,7 @@ describe('ReactPerformanceTracks', () => {
                 ['  data', ''],
                 ['    deeply', ''],
                 ['      nested', ''],
-                ['–       numbers', 'Array'],
+                ['-       numbers', 'Array'],
                 ['+       numbers', 'Array'],
               ],
               tooltipText: 'App',
diff --git a/packages/shared/ReactPerformanceTrackProperties.js b/packages/shared/ReactPerformanceTrackProperties.js
index f088d51025b..a2063584bdf 100644
--- a/packages/shared/ReactPerformanceTrackProperties.js
+++ b/packages/shared/ReactPerformanceTrackProperties.js
@@ -279,7 +279,7 @@ export function addValueToProperties(
   properties.push([prefix + '\xa0\xa0'.repeat(indent) + propertyName, desc]);
 }
 
-const REMOVED = '\u2013\xa0';
+const REMOVED = '-\xa0';
 const ADDED = '+\xa0';
 const UNCHANGED = '\u2007\xa0';