Function check_directory_name_consistency 

pub fn check_directory_name_consistency(
    parsed: &[ParsedFile],
) -> Result<(), Vec<(PathBuf, CompileError)>>

Within a multi-file unit (i.e., 2+ files in the same directory that share a qualified name), every file must declare exactly the same name.

In v0.4 the same directory may contain multiple single-file units (one commons and one context, say), provided each file’s path matches the last segment of its declared qualified name. Mixed-name files in one directory are only flagged when they collide on the same name (handled by check_group_kind_consistency) or when path/name alignment fails.

Each error is paired with the project-relative identity_path of the file its primary span belongs to (#696) so the CLI can render it against that file’s source. The “first file” it compares against is a different file, so its location is carried as a note (not a label, which would underline this file’s own text).