Added E2E test file tests/e2e/test_update_issue_add_multiple_labels.py with 7 comprehensive tests: 1. test_update_issue_add_multiple_new_labels - Creates 3 new labels for an empty issue 2. test_update_issue_add_multiple_existing_labels - Selects 3 existing labels 3. test_update_issue_add_mix_of_new_and_existing_labels - Combines new and existing labels 4. test_update_issue_add_labels_to_issue_with_existing_labels - Adds to issue with labels 5. test_update_issue_multiple_labels_count_badge_shows_correctly - Verifies count badge 6. test_update_issue_add_labels_shows_in_dropdown_as_checked - Verifies .selected class 7. test_update_issue_add_five_labels - Tests adding 5 labels All 7 tests pass. Existing single-label tests still pass (5 tests).