Function repair_with 

pub async fn repair_with(
    m: &mut Metadata,
    sources: &[&dyn Source],
    profile: &CapabilityProfile,
    ctx: &FetchContext,
) -> QualityReport

Repair the U+FFFD fields of m that a source can supply (title and venue), asking each of sources that can serve the DOI at most once, and record each repair in [doiget].repaired_fields.

Authors, publisher and abstract are detected but never repaired: no enabled source returns them in a shape that can be compared character by character with Crossref’s (Family, Given). A source that fails is skipped with a warning; repair is best-effort and never fails the call.