Function load_or_build 

pub fn load_or_build(
    layout: &RepoLayout,
    tree: &Tree,
    filter: &[PathBuf],
) -> Result<SparseOutcome, SparseBuildError>

Revalidate a cache witness or build it from authenticated local metadata. Unsupported filters and oversized witnesses retain the existing full-metadata restoration path. Cache failures are disposable misses.

Errors

Invalid local trees or a failed self-verification return a build error.