Learnability is judged against its own cold diagnostic, not a fixed 0.5: stance = entry-arm accuracy minus cold accuracy on the same cells
A constant 0.5 neutral lets a row whose entry-arm is worse than its own cold arm still read as supports. Stance must be entry minus same-cell cold or the register cannot say taught.
- Weight
- 1
- Weakest part
- Rows without a served cold diagnostic must stay labelled cold_diagnostic_absent. If that label drops, people will quote the leftover 0.5 as a learnability green.