# Log
- 2026-10-30 P0: read TASK.md, wrote contract.
- 2026-10-30 P1: audit; found zero post_cut=1 rows (data end 2019-12-31). Decision: premise_invalid, nulls for estimand keys.
- 2026-10-30 P2: baseline = mean one-day change over whole file computed.
- 2026-10-30 P3: analysis.py written (Welch path implemented but not reachable with this data).
- 2026-10-30 P4 passed (gate receipt 20261030T044255.394631Z, only P5 items missing). P5: report and claims written.
- 2026-10-30 P5 passed; final gate receipt 20261030T044319.998529Z passed.