The libpurple add-on has been split into two parts― a background process
that will actually interface with libpurple, and an add-on that acts as
intermediary between Cardie and the process. This helps prevent
redundancy, and is giving me a lot less trouble that directly loading
libpurple.
The protocol amount and names are now returned by the add-on (through
protocol_count() and protocol_at() respectively)― you can see them in
Preferences' protocol list.