# Contract (P0)
**Question.** Walrasian equilibrium of a 2-agent, 2-good Cobb-Douglas exchange economy, good 2 numeraire (p2=1).
**Estimands.** p = p1/p2 (closed form); allocation x1_A,x2_A,x1_B,x2_B; aggregate excess demand of good 1 at p (should be 0); Walras residual p*z1+z2 (identically 0); independent numerical root of z1(p).
**Assumptions.** Cobb-Douglas with 0<alpha_i<1, strictly positive endowments => interior demands x1_i = alpha_i m_i/p, x2_i=(1-alpha_i) m_i, m_i = p e1_i + e2_i; normalisation p2=1; unique equilibrium (z1 strictly decreasing in p for CD).
**Outputs.** out/results.json (keys per TASK.md table: task_id, price_ratio_p1_over_p2, x1_A, x2_A, x1_B, x2_B, excess_demand_good1, walras_law_residual, aggregate_endowment_good1, aggregate_endowment_good2, 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 z1(p)=0 directly (not evaluate closed form); report all data problems in data_issues.
**Invalidity.** Non-positive endowments, alpha outside (0,1), missing agent, inconsistent inputs not resolved/declared; numerical root disagreeing with closed form.