# Contract (P0)

Question: Walrasian equilibrium of a 2-agent, 2-good Cobb-Douglas exchange economy, good 2 numeraire. Estimands: p = p1/p2; allocation x1_A,x2_A,x1_B,x2_B; aggregate excess demand of good 1 at p (should be 0); Walras residual pz1+z2 (identically 0). Assumptions: Cobb-Douglas with 0<alpha_i<1, strictly positive endowments -> interior demands x1=alphaw/p, x2=(1-alpha)w, w=pe1+e2; normalisation p2=1; equilibrium unique for CD (gross substitutes). Closed form: p = sum_i alpha_i e2_i / sum_i (1-alpha_i) e1_i. Outputs: out/results.json (keys task_id, price_ratio_p1_over_p2, x1_A, x2_A, x1_B, x2_B, excess_demand_good1, walras_law_residual, aggregate_endowment_good1/2, price_ratio_numerical, feasibility, feasibility_reason, data_issues, n_input_rows, n_analysed, random_seed), out/report.md (6 sections), out/analysis.py, out/claims.json. Information rules: only data/ files; numerical validation must root-find aggregate excess demand of good 1 in p (not evaluate the closed form); report all data issues in data_issues. Invalidity: non-positive endowments or alpha outside (0,1); missing agent; inconsistent inputs not resolved.