Step 4 · Tactile differentiator
Flip the COA simultaneity gate. Watch the verdict change.
The same physical input (residual brake pressure + rising throttle) is feasible or a violation depending on whether the driver's COA permits simultaneity. APEX reads the COA at tensor level; existing tools cannot.
The /judges page carries an interactive toggle. Click `coa_overlap_flag = 1` to `0` and the projector verdict flips from `feasible` to `violation`. That is the load-bearing differentiator nobody else in the field has.