Defect: _pick_target_period treated "month sales < 30% of 6-month avg" as
"period not closed", so 2026-08 (actually closed: 3103 carry-forward vouchers
present) was skipped because of a low-sales off-season month, pinning the five
F_BEP* KPIs at 2026-07.
Fix: add _is_period_closed() - primary signal voucher_details
(carry_forward=1 AND subject_code='3103'), secondary signal
ZXT_LANDING_DIR/{YYYY.MM}/check.md containing both "issue PASS" and
"P&L carry-forward PASS". _pick_target_period now scans candidate months desc
and returns the first closed one, with no sales filtering; the old sales
threshold path is kept only as a fallback (warns "sales-threshold fallback").
Scope: run_derive() formulas, collector, kpi_definitions and cron untouched.
Verified: period=2026-08; 167.5 / 60.4 / 39.6 / 118.7 / 85.2;
F_BEP_COVER 2026-08 red pending, 2026-07 pending resolved; idempotent on re-run.
Hermes CI Fix