-- Migration 007: one current edge per (source, target, type).
-- The seed upsert previously conflicted on (source_id, target_id, type,
-- valid_from) — valid_from is now() at insert, so the conflict never fired
-- and every re-ingest duplicated all current edges. Dedupe (keep earliest
-- valid_from), then enforce uniqueness on current edges with a partial
-- unique index the upsert can target.

DELETE FROM relationships r
USING relationships keep
WHERE r.valid_to IS NULL AND keep.valid_to IS NULL
  AND r.source_id = keep.source_id
  AND r.target_id = keep.target_id
  AND r.type      = keep.type
  AND r.valid_from > keep.valid_from;

CREATE UNIQUE INDEX IF NOT EXISTS uq_rel_current
    ON relationships(source_id, target_id, type)
    WHERE valid_to IS NULL;