I'm testing out the msig capabilities. Once an msig transaction has been proposed , how can you determine who has already signed it and who needs to sign it? Is there any way to notify the accounts who need to sign through the blockchain?
Both multisig-approval-tables (approvals and approvals2) contain vectors for "requested_approvals" and "provided_approvals".
See here: msig.hpp
Notifications can be implemented in different ways. Probably sending a transaction containing a memo to the different accounts is the easiest way.