Count only what you know
Enter the live and blank shell counts you can see; the helper never reads or guesses the hidden order.
Use the ratio
The transparent formula is live divided by live plus blank, which gives a bounded share rather than a guaranteed next shell.
Account for actions
Peek, reorder, swap, and self-or-target choices can change the decision context even when the count stays the same.
Prefer a recovery line
If the result is close, keep a handcuff, heal, or turn-control item available instead of treating a small edge as certainty.
Reset after a new count
Update the inputs whenever a shell is consumed or revealed so the next ratio reflects the current visible state.