Source: MIZOKI audit 2026-09-06 (pinned fc8b03f9) → work-order backlog 2026-09-08 (docs/audits/AUDIT_WORK_ORDERS_2026-09-08.md). Findings are hypotheses until reproduced on current main (WO-00).

Finding: Causal credit labels first-N conversions anticipated, rest caused; swapping two timestamps moved summed caused value $1,000 → $10 [R10]. Files: services/measurement-rails/causal_credit.py, main.py, test_causal_credit.py. Fix: compute incremental revenue/profit at the assignment-unit level with intervals; any per-purchase allocation is labeled convention, never causal. Acceptance: permutation test: reordering purchase timestamps within a cell does not change the estimand; output schema carries estimand, ci_low, ci_high, n_units. Depends on: WO-00.