feat(core): Make global addBreadcrumb write to the isolation scope instead of current scope

packages/core/src/hub.ts

@@ -402,7 +402,7 @@ export class Hub implements HubInterface {
    */
   public addBreadcrumb(breadcrumb: Breadcrumb, hint?: BreadcrumbHint): void {
     // eslint-disable-next-line deprecation/deprecation
-    const { scope, client } = this.getStackTop();
+    const { client } = this.getStackTop();
 
     if (!client) return;
 
@@ -421,15 +421,8 @@ export class Hub implements HubInterface {
 
     client.emit('beforeAddBreadcrumb', finalBreadcrumb, hint);
 
-    // TODO(v8): I know this comment doesn't make much sense because the hub will be deprecated but I still wanted to
-    // write it down. In theory, we would have to add the breadcrumbs to the isolation scope here, however, that would
-    // duplicate all of the breadcrumbs. There was the possibility of adding breadcrumbs to both, the isolation scope
-    // and the normal scope, and deduplicating it down the line in the event processing pipeline. However, that would
-    // have been very fragile, because the breadcrumb objects would have needed to keep their identity all throughout
-    // the event processing pipeline.
-    // In the new implementation, the top level `Sentry.addBreadcrumb()` should ONLY write to the isolation scope.
-
-    scope.addBreadcrumb(finalBreadcrumb, maxBreadcrumbs);
+    // eslint-disable-next-line deprecation/deprecation
+    this.getIsolationScope().addBreadcrumb(finalBreadcrumb, maxBreadcrumbs);
   }
 
   /**

packages/core/test/lib/scope.test.ts

@@ -473,6 +473,38 @@ describe('Scope', () => {
       );
     });
   });
+
+  describe('addBreadcrumb()', () => {
+    test('adds a breadcrumb', () => {
+      const scope = new Scope();
+
+      scope.addBreadcrumb({ message: 'hello world' }, 100);
+
+      expect((scope as any)._breadcrumbs[0].message).toEqual('hello world');
+    });
+
+    test('adds a timestamp to new breadcrumbs', () => {
+      const scope = new Scope();
+
+      scope.addBreadcrumb({ message: 'hello world' }, 100);
+
+      expect((scope as any)._breadcrumbs[0].timestamp).toEqual(expect.any(Number));
+    });
+
+    test('overrides the `maxBreadcrumbs` defined in client options', () => {
+      const options = getDefaultTestClientOptions({ maxBreadcrumbs: 1 });
+      const client = new TestClient(options);
+      const scope = new Scope();
+
+      scope.setClient(client);
+
+      scope.addBreadcrumb({ message: 'hello' }, 100);
+      scope.addBreadcrumb({ message: 'world' }, 100);
+      scope.addBreadcrumb({ message: '!' }, 100);
+
+      expect((scope as any)._breadcrumbs).toHaveLength(3);
+    });
+  });
 });
 
 describe('isolation scope', () => {