Margin = total available person-days minus weekly demand (overall surplus). Bus Factor = how many people could call in sick before a specific slot goes unfilled — it finds the single weakest day/shift for each position. A position can have a healthy margin but a bus factor of 1 if one particular slot is tight.
Staff qualified for 2+ positions create hidden dependencies — when the solver assigns them to one position, every other position they could fill loses capacity. Competing = how many positions with active demand are pulling on this person's available days. Sole Expert = this person is the only L3 for that position; losing them means high-demand slots (needing 2+ staff) can't meet the expert requirement.
The solver requires at least one L3 expert whenever a slot needs 2+ staff. This section checks each of those high-demand slots to see how many L3 experts are actually available. Thin = only 1 expert available for a slot, so one absence breaks the constraint. Hover over a slot to see which experts cover it.