Position sizing (advisory)

dollarsAtRisk = accountSize × riskFraction        default 1%
shares        = floor( dollarsAtRisk / risk )      risk = |entry − stop|

Shown as worked arithmetic in the UI. Notable property: position size is a function of stop distance, not of conviction — a wide stop means fewer shares for the same dollar risk. The engine does not size up on confidence (a deliberate v1 choice; fractional-Kelly sizing is a v2+ question that requires calibrated probabilities first).