-- Migration 121: document lead_time_days as NOT COLLECTED
-- ─────────────────────────────────────────────────────────────────────────────
-- Verified 2026-07-04: lead_time_days is 0 % populated on every time-series table
--   price_observations : 1,378,984 rows → 0 filled
--   stock_observations :    85,406 rows → 0 filled
--   stock_snapshots    :         0 rows (LLM-crawler path is dormant)
--
-- The plumbing exists (crawler-llm stock-schema captures lead_time_days and
-- writes it to stock_snapshots; upsertPriceObservation accepts a leadTimeDays
-- param) but the ACTIVE ingestion path never supplies a value, and there is no
-- evidence any tracked vendor page exposes a machine-readable lead time.
--
-- Rather than fabricate a default, this migration documents the column as
-- not-collected so no consumer invents one. Lupo already renders "k.A." / "n/a"
-- and blends only the two signals it actually measures (availability, breadth).
-- Populating this field is a SCRAPER-side task (extend the active crawlers to
-- read a delivery/lead-time badge) — out of scope for a schema migration.
-- ─────────────────────────────────────────────────────────────────────────────

COMMENT ON COLUMN price_observations.lead_time_days IS
  'NOT COLLECTED (verified 2026-07-04): 0 % populated. The active scraper path never '
  'supplies a lead time. Do NOT default this — treat NULL as "unknown / not captured". '
  'Populating it requires scraper work (read a delivery-time badge on the vendor page).';

COMMENT ON COLUMN stock_observations.lead_time_days IS
  'NOT COLLECTED (verified 2026-07-04): 0 % populated. Treat NULL as "unknown". See '
  'price_observations.lead_time_days.';

COMMENT ON COLUMN stock_snapshots.lead_time_days IS
  'Captured by the crawler-llm path (stock-schema.lead_time_days) but that path is '
  'currently dormant (0 rows). Treat NULL as "unknown / not captured".';

INSERT INTO _migrations (filename)
VALUES ('121-lead-time-not-collected-doc.sql')
ON CONFLICT (filename) DO NOTHING;