cross-table-lineagelisted

# cross-table-lineage - **Roadmap feature:** F039 (PROPOSED at plan time; not yet a `docs/roadmap/roadmap.md` ledger row -- see "See also" below). **On-disk spec:** `specs/099-cross-table-lineage-impact/`. - **Authority category:** Product Module / `artifact-writing` (the F024 enumerated declaration -- see `docs/architecture/product-modules.md`). Seshat BI can already answer "does this ONE source drift from its own profile" (F014) and "what does this ONE KPI derive from, conceptually, inside the contract layer" (spec 044). Neither answers the question a table owner actually asks the moment a column changes: if this column changes shape or disappears, which migrations, metric contracts, TMDL measures, and dashboard visuals sit downstream of it, and how far does the chain reach before it runs out of committed evidence? Today that question is answered by hand -- `docs/demo/net-sales-end-to-end-readiness-trace.md` proves it can be done for exactly one KPI, on paper, by a human reading five artifact families in sequence. This skill GENERALIZES that trace's shape (evidence tiers, hop-by-hop citation) into a regeneratable artifact for any column or metric contract. It derives evidence only; it never fabricates a link, never scores impact, and never decides what must be re-reviewed. ## Boundary against neighbouring shipped work (read first) - **Spec 044 KPI Derivation-Lineage Contract** (`specs/044-kpi-derivation- lineage/`, ratified, no runtime code) authors a `Derives f