Before revision:  The Designer's optimization problem (designing a custom suite for the Agent so as to optimize, through the Agent's optimum reaction, the Designer's revenue), while NP-hard  , has an FPTAS.
After revision:  The Designer's optimization problem (designing a custom suite for the Agent so as to optimize, through the Agent's optimum reaction, the Designer's revenue), while NP-hard to approximate within any finite ratio; however, the special case, while still NP-hard , has an FPTAS.