-- Graph layer: edges with provenance and validity (see data-model.md).
-- Optional: used when explicit graph and conflict resolution are needed.

CREATE TABLE IF NOT EXISTS edges (
  id TEXT PRIMARY KEY,
  from_type TEXT NOT NULL,
  from_id TEXT NOT NULL,
  to_type TEXT NOT NULL,
  to_id TEXT NOT NULL,
  relation TEXT NOT NULL,
  confidence REAL,
  source TEXT,
  valid_from TIMESTAMPTZ NOT NULL DEFAULT NOW(),
  valid_to TIMESTAMPTZ
);

CREATE INDEX idx_edges_from ON edges(from_type, from_id);
CREATE INDEX idx_edges_to ON edges(to_type, to_id);
CREATE INDEX idx_edges_relation ON edges(relation);
CREATE INDEX idx_edges_valid ON edges(valid_from, valid_to);