She’s guiding them to the straight and (not so) narrow. Diversity in the workplace is a critical issue, especially in Silicon Valley, and lawyer Joelle Emerson is on the case. Her firm, Paradigm, is helping more than a dozen tech companies — including Pinterest — select, develop and retain more diverse staffs. Opening recruitment to more schools can be a good start. But there’s likely no finish line, Emerson says, and firms looking to make real changes need to set diversity goals —and remain dedicated to them.