Sort the guest list on the table.
Every invitation is a card. Drag them into tiers against the seats and the budget; broken rules show up as red tape. Then ask for a second pair of eyes: it names the tensions and proposes moves you can accept one by one.
The brief - the venue, the house rules (plus-ones, children, colleagues). The reviewer treats it as binding.
How the sort is checked
Everything on the board runs in your browser before you sign in: the seat, cost and expected-headcount sums (seats × the card's likelihood of coming), every tier rule, the pairs and the coverage by side and group. A seat cap or budget marked counting the tiers above adds up this tier and every tier above it - that is how a venue's seated capacity works across an A and a B list. The reviewer never does arithmetic; it is sent the sums and the broken rules, and every move it proposes is checked against your rules before it is drawn. A move that would break one is drawn with the rule it would break.