We need good evals for activation faithfulness

Tl;dr: There should be a clear, well-designed eval on activation faithfulness: whether the model activations a monitor reads remain a trustworthy surface when the model suspects/knows it is being monitored. We provide an appendix with preliminary results towards such an eval in case people want to build off of it, but we think way more work needs to be done here.—There is currently a lot of discussion around the precarious state of CoT monitorability. To our knowledge, CoT monitorability is thre...