Function declared_edges 

fn declared_edges(
    scan: DataFrame,
    window: &GraphQueryWindow,
) -> Result<DataFrame>

The declared-edge branch: the latest revision per edge key as of the queried window (mito dedups on primary key + observed_at, so re-asserting an edge stores a new revision), filtered by business-validity overlap.

valid_from defaults to the declaration time; a NULL valid_until means the edge holds while its row exists (TTL retires it), so window_end / fresh_until take the window’s upper bound. The output observed_at is synthesized inside the queried range: the scan’s filters are re-applied above the computed table, and the physical revision time would fail them.