New York City’s three mayoral candidates, Zohran Mamdani, Andrew Cuomo, and Curtis Sliwa, will take the stage tonight for their first general election debate. Meanwhile, the NYPD’s gang database has shrunk by nearly 40 percent in three years, but a new oversight report finds thousands of people were kept in the system longer than allowed because of programming errors. Plus, at Belmont Park, crews have hoisted the final steel beam, marking a major step in the Long Island racetrack’s full rebuild.