Function source_observations_to_graph 

pub fn source_observations_to_graph(
    repo_id: &RepoId,
    source_path: &str,
    content_hash: &str,
    observations: &[SourceObservation],
) -> SourceGraphFacts

Converts exact focused source observations into graph-ready facts.

Ambiguous and incomplete observations remain in the persisted extractor payload but are not promoted to factual graph nodes or links.