The server compiles units one by one and never links, so a call to a
function declared only by its prototype (an invented helper, or a member
declared in a header and never written) compiled and could merge; main
would not link. A newly declared function at file or class scope must be
defined in the submission, exist elsewhere in the repository, or be a
known function of the original (by name or fn_ ID).
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
