Add optimality note: exhaustive enumeration confirms magnitude 2 is minimum

README.md

@@ -55,6 +55,10 @@ The weights [-1, +1] directly implement ¬x + y.
 | Bias | 0 |
 | Total | 3 parameters |
 
+## Optimality
+
+Exhaustive enumeration of all 25 weight configurations at magnitudes 0-2 confirms this circuit is **already at minimum magnitude (2)**. There is exactly one valid configuration at magnitude 2, and no valid configurations exist below it.
+
 ## Properties
 
 - Linearly separable (unlike XOR)