ZLK simulation results in a_c−m_c (left) and m_c−e_c space (right). Each point represents one companion configuration tested across 18 different initial conditions. Blue points indicate companion configurations where ZLK migration is too slow (t_HN > 10 Gyr) for all 18 initial conditions. Gray points show mixed failure conditions where ZLK migration either is too slow (t_HN > 10 Gyr), is too fast (t_HN < 1 Gyr), or causes GJ 436 b to reach the Roche limit (a_b < a_R). Green points represent plausible configurations for which at least one of the 18 suites reproduces the present-day orbit. For each plausible companion configuration, only one to three of the 18 initial condition suites plausibly reproduce the present-day orbit.