Status: OUT
The DP-to-rolling-variable reduction extends the O(1)-space running accumulator pattern from streaming to dynamic programming, collapsing O(n) DP tables to O(1) rolling variables while preserving recurrence correctness for all inputs within LeetCode constraints.
Rolling-variable DP is an instance of the running accumulator pattern, gated by the length-ge-2 precondition that crashes on degenerate input
Depends on (SL): min-cost-dp-uses-constant-space, o1-space-via-running-accumulators
Unless: min-cost-assumes-length-ge-2