Binary interaction outcomes—noninteracting (red), Case C transfer (green), and Case B transfer (blue)—as a function of initial orbital separation and donor mass M₁, assuming a fixed mass ratio q₂ of 0.9. Hatched regions indicate models that undergo CEE. The boundary between interacting and noninteracting binaries shifts to larger separations with increasing total binary mass. A complex interaction landscape emerges at M₁ ≲ 20, M_⊙ and separations ≲3200 R_⊙, where multiple interaction channels coexist. CEE occurs predominantly for M₁ ≲ 28 M_⊙ and separations ≲2500 R_⊙.