Proposition: Intrinsic reports cannot implement the guard

No rule depending only on the intrinsic edge-length and face-area tables can recognize the exact incoming event parameter throughout the admitted incoming domain. This remains true with arbitrarily accurate reports, including the exact unrounded tables.

Proof. For every $s<0$ and for the incoming germ at $s=0$, all intrinsic tables in Propositions prop:lengths and prop:areas are identical. Their event predicates differ. Any function of the same observed table must have the same value on both.