Function resolve_fetch_invocation 

pub fn resolve_fetch_invocation(
    config: &ConfigSet,
    remote: Option<&str>,
    refspecs: &[String],
    current_branch: Option<&str>,
) -> FetchInvocation

Classify grit fetch [<remote>] [<refspec>…] positionals (no refspec parsing).

When the CLI supplies a first positional (remote), it is always the repository (configured name, URL, scp-style host:path, or path) — matching Git. Remaining positionals are refspecs. With no first positional, an initial token that looks like a repository is consumed as the remote; otherwise the remote comes from configured_remote_for_fetch for current_branch and every token is a refspec.

current_branch is the short name of the checked-out branch (None when HEAD is detached).