Function record_session_use 

pub async fn record_session_use(
    db: &Surreal<Db>,
    session_id: &str,
    entity_ids: &[String],
) -> Result<u32, GraphError>

Record that a session touched these entities, without judging the outcome.

The passive half of the feedback loop: ingestion knows which entities a session produced or reinforced, and says so here. A later graph feedback <session> supplies the outcome and this is what tells it which entities the outcome applies to.

Idempotent per session: re-ingesting a session rewrites its records rather than accumulating duplicates. Utility scores are untouched — an unadjudicated session is not evidence of usefulness.