v3.24.0 — Holistic Review VII & ext-* Tail Closure Phases 222–228. 8-axis review (0 High/Critical) → 14-item fix-set (224); ADR-0023 ext-* grammar freeze + UX-03 hint (225); po:projection_cols multi-column projection struct — po's first ad-hoc named struct, allKinds 27→28 (226); po:sum_join LEFT JOIN roll-up — the codebase's first GROUP BY, allKinds 28→29 (227); freeze (228). CORR-01 (po:read+aggregate reject) consistent across all 4 kinds. Additive/opt-in/byte-equal-when-absent; single authorised break API-01. Ratchet 117/62/22/40/5 held; 0 net-new deps; all gates green.