This is an excellent break down of multiplayer-AI!
At we thinking about multiplayer-AI for coding as multiplayer context engineering.
One important requirement is that the shared context must be observable and mutable to the entire team.
The implication is that is basically impossible if you are sharing agent sessions directly. For non-trivial work, that's like dropping into a massive 100+ message slack thread and trying to build a mental model for what's happening.
You need surface that makes it easy to explore your ideas in-depth with and agent AND easy for your teammate to glance at and provide feedback.
It needs to be human-legible and agent-useful.