# Log
- 2026-10-30 P0: read TASK.md, wrote contract.
- 2026-10-30 P1: audited data; clean, balanced, no exclusions.
- 2026-10-30 P2: baseline OLS iid SE = 0.282 (p=0.0007).
- 2026-10-30 P3: decision: CR1 cluster SE by school, t(G−1=39) reference; ICC via one-way ANOVA on residuals after arm means. No randomness (seed null).
- 2026-10-30 P4: re-run identical; all checks pass.
- 2026-10-30 P5: report and claims written.