One trajectory, N doctors, one point each, walked in sequence.

A different product from the solo walk, not a variant of it. The solo walk captures one physician's evolving judgment about a patient; this captures how clinicians build on each other's reasoning — doctor k reads doctor k−1's committed assessment before writing their own, exactly like a real handoff.

What this commits, atomically enough that a partial state is not servable: the rotation as assignment rows, walk_mode='relay' on every point, and distribution left at assigned_only. Only doctor #0's point is serveable on send; everyone else's assignment exists and is held closed by the relay gate until the chart reaches them.