Decode the logical definition that produced a workflow.

Fetch the execution snapshot for a workflow, or nil.

Return the stored logical and expanded execution graphs for a workflow.

expansions is the run-time half: %{logical_id => [%{id, item_index}]} for any node that fanned out dynamically. The compiled graph is an immutable snapshot written before those nodes existed — it carries the expander marked "fan_out" => "dynamic" and nothing beneath it — so a view that wants to draw what actually ran reads them from here and grafts them on. It is empty for every workflow without a dynamic fan-out, which includes every workflow compiled before there was one.