Party member
A party member is a standing actor in the workspace, a person or an agent, with its own identity, permissions, and ability to carry active work over time.
Not every actor in Masterforce is a party member. What qualifies is standing identity: something the system recognizes on an ongoing basis, that acts with its own defined permissions, and that can be handed work that persists beyond a single exchange. People are party members. So are system and workspace agents. The assistant is deliberately not, because it has no standing identity of its own.
Assistant
Party members can be mentioned directly, assigned active work, and woken for background execution. That is the practical test for whether something is a party member: can you hand it ongoing responsibility and expect it to still be there tomorrow.