UI: Fix mapped task XCom navigation from Grid apache#64875 (apache#65192)

* UI: Fix mapped task XCom navigation from Grid

* Add regression test for mapped task navigation

Author: vishakha1411

airflow-core/src/airflow/ui/src/utils/links.test.ts

@@ -271,4 +271,16 @@ describe("buildTaskInstanceUrl", () => {
       }),
     ).toBe("/dags/my_dag/runs/run_1/tasks/group/my_group");
   });
+
+  it("should not preserve sub-routes for mapped tasks without map index", () => {
+    expect(
+      buildTaskInstanceUrl({
+        currentPathname: "/dags/old_dag/runs/old_run/tasks/old_task/mapped/2/xcom",
+        dagId: "new_dag",
+        isMapped: true,
+        runId: "new_run",
+        taskId: "new_task",
+      }),
+    ).toBe("/dags/new_dag/runs/new_run/tasks/new_task/mapped");
+  });
 });

airflow-core/src/airflow/ui/src/utils/links.ts

@@ -84,8 +84,10 @@ export const buildTaskInstanceUrl = (params: {
 }): string => {
   const { currentPathname, dagId, isGroup = false, isMapped = false, mapIndex, runId, taskId } = params;
   const groupPath = isGroup ? "group/" : "";
-  // Task groups only have "Task Instances" tab, so never preserve tabs for groups
-  const additionalPath = isGroup ? "" : getTaskInstanceAdditionalPath(currentPathname);
+  const additionalPath =
+    isGroup || (isMapped && (mapIndex === undefined || mapIndex === "-1"))
+      ? ""
+      : getTaskInstanceAdditionalPath(currentPathname);
 
   let basePath = `/dags/${dagId}/runs/${runId}/tasks/${groupPath}${taskId}`;