Status: IN
The selective defense pattern (invest in efficiency-improving conditions like early exit, skip robustness-improving conditions like input validation) is a specific instantiation of the quality equilibrium: the LeetCode judge rewards algorithmic efficiency but is indifferent to engineering robustness, so defensive investment follows the reward gradient exactly.
Selective defense and quality equilibrium share the same causal root (judge reward signal); combining makes explicit that condition-checking investment is reward-tracking behavior
Depends on (SL): selective-defense-explained-by-judge-boundary, quality-equilibrium-self-reinforcing