A shared Flood boundary explains the whole SP family
The SP Flood cap begins with independently declared kinds of information: ordered begetting intervals, a Noah–Flood relation, and a baseline lifespan ledger. In the native SP G2 frame, primary Noah is placed at 3493 BC and Flood start at 2893 BC. Working backward through the nine completed begetting intervals reconstructs every birth from Adam through Lamech. Lamech's 53rd counted year contributes 52 completed units in this chain.
For each birth B, the inclusive capacity to Flood start is B − 2893 + 1. The rule selects the smaller of that capacity and the baseline lifespan. Applied to all nine rows, it gives Adam 930, Seth 912, Enosh 905, Kenan 910, Mahalalel 895, Jared 847, Enoch 365, Methuselah 720, and Lamech 653. Six baseline lives remain unchanged; three meet the shared boundary. Their inclusive counts place the selected deaths at Flood start, while the other six deaths retain ordinary subtraction.
The three reductions, 115, 249, and 124 relative to the MT ledger, generate every pre-Flood Cumulative displacement and sum to 488. Eber and official Terah supply a separate 120, producing the established 608 difference. The shared rule thus explains both the local changes and their accumulated effect; Noah remains outside the cap domain.
Sources: File18 §2.1.3, §3.1, §3.1.3, §6C; Research Strategy §5, Stage B, §8, main unresolved reconstruction task.