Function diff_sets_in 

pub fn diff_sets_in(
    old: &[Package],
    new: &[Package],
    context: &[Package],
) -> DiffReport

diff_sets, with context: packages that a type reference resolves against without being compared. This entry point shares one context. ridl diff and the MCP server use per-side contexts through diff_workspaces_with_contexts: the built-in ridl.std plus each side’s own remote packages, compiled from source or retained in a snapshot directory, so historical layouts never borrow current remote definitions. ridl check’s baseline desk check passes one shared context and judges no encoding.