Week 2 pits San Francisco’s offense against a murky QB clock: Brock Purdy is out with a toe injury, Mac Jones starts, and Adrian Martinez has been promoted to the active roster as a ready emergency option. Martinez, a UFL MVP who bided time with the Jets, could make his NFL debut if Jones exits. The 49ers’ plan hinges on Jones staying healthy while Martinez remains a ceiling play ready to capitalize on any misstep.