A natural ceiling is exactly the natural cutoff representing the strict real
inequality p < y.
The exact boundary condition needed for the natural recurrence. Unlike the
coarser ynat^3 ≤ Dnat, this condition is preserved by choosing
ynat = ceil y: every integer p < ceil y satisfies p < y.
Exact section14ExtendedT recurrence at a ceiling cutoff. This is the
natural-API form needed at the Case-II endpoint.
The Case-I endpoint y = D^(1/(β+1)), with the source value β=2,
feeds the natural ceiling recurrence without the false condition
ceil(y)^3 ≤ Dnat.
The legal-domain bridge at the natural endpoint. The power condition is kept explicit: it is not implied by a real power coordinate after taking a ceiling.
Under the legal-domain power condition, the endpoint inequality required by Case II is exactly the corresponding source-faithful Case-I inequality. This statement has no endpoint-bound hypothesis and makes the remaining analytic obligation explicit.
Exact Case-I endpoint inequality consumed by the Case-II normalized
assembly, transported from the source-faithful parity sum to the natural
section14ExtendedT API. The real endpoint is represented by ynat = ceil y,
and the source/extended identification requires the explicit legal-domain
power condition.
Case-II normalized assembly with no opaque hendpoint argument: the exact
source-faithful Case-I endpoint inequality is transported through the legal
bridge internally.