CREATE TABLE IF NOT EXISTS contact_merge_history (
    id BIGSERIAL PRIMARY KEY,
    target_contact_id INTEGER NOT NULL REFERENCES contacts(id) ON DELETE RESTRICT,
    source_contact_id INTEGER NOT NULL,
    source_snapshot JSONB NOT NULL,
    moved_relations JSONB NOT NULL DEFAULT '{}'::jsonb,
    merged_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
);

CREATE INDEX IF NOT EXISTS idx_contact_merge_history_target
    ON contact_merge_history(target_contact_id, merged_at DESC);

COMMENT ON TABLE contact_merge_history IS
    'Audit trail for destructive contact merges. Source contact snapshots and moved relation counts are retained.';