Accepted replay retains the exact input head.
A nonsingleton accepted chain has all steps and a terminal identity.
The last entry of an accepted replay has exactly the common divisors of
P and F*P' in the semantic field, including singleton chains.
The terminal polynomial in an accepted query replay is associated to the semantic gcd, whether that gcd is constant or nonconstant.
The replay's literal constant-tail guard means a nonzero constant after interpretation, without requiring a canonical representative of one.
For the derivative replay, the exact constant-tail guard is equivalent to squarefreeness over the semantic ordered field.
Query production succeeds exactly when the endpoint guards and semantic
squarefreeness hold. There is no exhaustion case hidden in the Option.