extension PureYAML.Parsing {
    /// A tag shorthand (`!handle!suffix`) whose named handle was never declared by a `%TAG`
    /// directive in the document where it is used. The scanner records these rather than rejecting,
    /// so a permissive parse still produces a value while the diagnostic layer can surface the issue.
    struct TagHandleIssue: Equatable {
        var line: Int
        var column: Int
        /// The undeclared handle, including its surrounding `!`, e.g. `!e!`.
        var handle: String
    }
}