There is always a limit unless you start scaling horizontally in the sense that you have multiple accounts via subscription or API. There is always some limit to any single account, even via API.
I'm thinking the persistent agent is something that can't scale to multiple agents. Imagine only one agent you can invoke as many times as you want on a single account, but it cannot invoke subagents or scale itself. It's just always there ready to do work when you need it. But it behaves as "one".
This would be trivial to implement. Of course, if you have the money, you can have multiple $500 subscriptions and have multiple persistent agents.
I'm thinking the persistent agent is something that can't scale to multiple agents. Imagine only one agent you can invoke as many times as you want on a single account, but it cannot invoke subagents or scale itself. It's just always there ready to do work when you need it. But it behaves as "one".
This would be trivial to implement. Of course, if you have the money, you can have multiple $500 subscriptions and have multiple persistent agents.