feat(ios): Add attachAllThreads option

Expose the Cocoa SDK's `attachAllThreads` option so it can be
configured from JS via `Sentry.init()`. When enabled, full stack
traces for all threads are attached to captured events on iOS.

Closes #5959

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: antonis

CHANGELOG.md

@@ -11,6 +11,7 @@
 ### Features
 
 - Enable "Open Sentry" button in Playground for Expo apps ([#5947](https://github.com/getsentry/sentry-react-native/pull/5947))
+- Add `attachAllThreads` option to attach full stack traces for all threads to captured events on iOS ([#5959](https://github.com/getsentry/sentry-react-native/issues/5959))
 
 ### Dependencies
 

packages/core/src/js/options.ts

@@ -96,6 +96,14 @@ export interface BaseReactNativeOptions {
    */
   attachThreads?: boolean;
 
+  /**
+   * When enabled, full stack traces for all threads are attached to all captured events.
+   *
+   * @default false
+   * @platform ios
+   */
+  attachAllThreads?: boolean;
+
   /**
    *  When enabled, certain personally identifiable information (PII) is added by active integrations.
    *

packages/core/test/wrapper.test.ts

@@ -224,6 +224,23 @@ describe('Tests Native Wrapper', () => {
       expect(NATIVE.enableNative).toBe(true);
     });
 
+    test('passes attachAllThreads to native SDK', async () => {
+      await NATIVE.initNativeSdk({
+        dsn: 'test',
+        enableNative: true,
+        autoInitializeNativeSdk: true,
+        attachAllThreads: true,
+        devServerUrl: undefined,
+        defaultSidecarUrl: undefined,
+        mobileReplayOptions: undefined,
+      });
+
+      expect(RNSentry.initNativeSdk).toHaveBeenCalled();
+      // @ts-expect-error mock value
+      const initParameter = RNSentry.initNativeSdk.mock.calls[0][0];
+      expect(initParameter).toHaveProperty('attachAllThreads', true);
+    });
+
     test('filter integrations when initializing Native SDK', async () => {
       await NATIVE.initNativeSdk({
         dsn: 'test',