Gain formula
gain = GAIN_RATE · ln(1 + headroom) · ∛(risk multiplier).
Definition
Trust is earned sub-linearly: a successful action adds gain = GAIN_RATE · ln(1 + (ceiling − score)) · cube-root(R). Headroom shrinks as the score approaches its ceiling (the last points are hardest), and higher-risk successes are worth more via the cube-root of the risk multiplier.