Heckscher-Ohlin in a Box — Why Trade Patterns Look the Way They Do

Build the two-country, two-good, two-factor Heckscher-Ohlin model from first principles for the Costaria-Boravia pair. Diagnose the trade pattern (Round 1), derive the Stolper-Samuelson distributional consequences and design a compensation mix (Round 2), then confront the model with the Leontief paradox and pick the right lens — Ricardo, H-O, Stolper-Samuelson, Krugman, Melitz, Grossman-Rossi-Hansberg — for each margin of the actual 2026 trade pattern (Round 3).