Function is_declared_capability_method 

pub fn is_declared_capability_method(field: &str, method: &str) -> bool

Is harness.<field>.<method> a declared capability method anywhere in the workspace?

Weaker than capability_method_entry on purpose: it answers existence without a contract, because the 280 methods harn-vm declares through #[harn_builtin] have no leaf-crate contract to return. Their bodies close over VM internals, so the declaration cannot move here — only its name can.

A consumer that needs the signature must still go through the installed manifest and accept that it is empty before the VM installs it. A consumer that only needs to reject a typo — harn check — can use this, and get the same answer whether or not a VM ever starts (#6101).