From af7ca0a89d246b44feb229e005df3337f1795cf9 Mon Sep 17 00:00:00 2001
From: s1gr1d <32902192+s1gr1d@users.noreply.github.com>
Date: Mon, 24 Nov 2025 11:26:51 +0100
Subject: [PATCH] feat(core): Use `maxValueLength` on error messages

---
 packages/core/src/utils/prepareEvent.ts | 13 ++++++++--
 packages/core/test/lib/client.test.ts   | 32 +++++++++++++++++++++++--
 2 files changed, 41 insertions(+), 4 deletions(-)

diff --git a/packages/core/src/utils/prepareEvent.ts b/packages/core/src/utils/prepareEvent.ts
index 9a4c4685e839..fd1cb62440f4 100644
--- a/packages/core/src/utils/prepareEvent.ts
+++ b/packages/core/src/utils/prepareEvent.ts
@@ -147,8 +147,17 @@ export function applyClientOptions(event: Event, options: ClientOptions): void {
   }
 
   const request = event.request;
-  if (request?.url) {
-    request.url = maxValueLength ? truncate(request.url, maxValueLength) : request.url;
+  if (request?.url && maxValueLength) {
+    request.url = truncate(request.url, maxValueLength);
+  }
+
+  if (maxValueLength) {
+    event.exception?.values?.forEach(exception => {
+      if (exception.value) {
+        // Truncates error messages
+        exception.value = truncate(exception.value, maxValueLength);
+      }
+    });
   }
 }
 
diff --git a/packages/core/test/lib/client.test.ts b/packages/core/test/lib/client.test.ts
index 19ef8a95dff5..2a2d77171880 100644
--- a/packages/core/test/lib/client.test.ts
+++ b/packages/core/test/lib/client.test.ts
@@ -21,7 +21,6 @@ import type { ErrorEvent, Event, TransactionEvent } from '../../src/types-hoist/
 import type { SpanJSON } from '../../src/types-hoist/span';
 import * as debugLoggerModule from '../../src/utils/debug-logger';
 import * as miscModule from '../../src/utils/misc';
-import * as stringModule from '../../src/utils/string';
 import * as timeModule from '../../src/utils/time';
 import { getDefaultTestClientOptions, TestClient } from '../mocks/client';
 import { AdHocIntegration, AsyncTestIntegration, TestIntegration } from '../mocks/integration';
@@ -37,7 +36,6 @@ const clientProcess = vi.spyOn(TestClient.prototype as any, '_process');
 
 vi.spyOn(miscModule, 'uuid4').mockImplementation(() => '12312012123120121231201212312012');
 vi.spyOn(debugLoggerModule, 'consoleSandbox').mockImplementation(cb => cb());
-vi.spyOn(stringModule, 'truncate').mockImplementation(str => str);
 vi.spyOn(timeModule, 'dateTimestampInSeconds').mockImplementation(() => 2020);
 
 describe('Client', () => {
@@ -263,6 +261,36 @@ describe('Client', () => {
       );
     });
 
+    test('does not truncate exception values by default', () => {
+      const exceptionMessageLength = 10_000;
+      const options = getDefaultTestClientOptions({ dsn: PUBLIC_DSN });
+      const client = new TestClient(options);
+
+      client.captureException(new Error('a'.repeat(exceptionMessageLength)));
+      expect(TestClient.instance!.event).toEqual(
+        expect.objectContaining({
+          exception: {
+            values: [{ type: 'Error', value: 'a'.repeat(exceptionMessageLength) }],
+          },
+        }),
+      );
+    });
+
+    test('truncates exception values according to `maxValueLength` option', () => {
+      const maxValueLength = 10;
+      const options = getDefaultTestClientOptions({ dsn: PUBLIC_DSN, maxValueLength });
+      const client = new TestClient(options);
+
+      client.captureException(new Error('a'.repeat(50)));
+      expect(TestClient.instance!.event).toEqual(
+        expect.objectContaining({
+          exception: {
+            values: [{ type: 'Error', value: `${'a'.repeat(maxValueLength)}...` }],
+          },
+        }),
+      );
+    });
+
     test('sets the correct lastEventId', () => {
       const options = getDefaultTestClientOptions({ dsn: PUBLIC_DSN });
       const client = new TestClient(options);