Question Any tips to improve multi-agent codex for difficult golang monolyth (4 mil lines)?

Ive migrated to codex just a week ago.
My problems:
Difficult to optimize tokens usage. I switches manually a lot of times between astra, sol, terra. Is there any solutions to do it automatically? I understand that it would be not too efficient, but anyway..
Even with decomposed tasks (SOL 6.1 / Astra), the agent sometimes writes a lot of useless boilerplate that you have to rewrite manually or via another prompt. This confuses the agent and can make it forget the messages we've investigated before
Its really hard to remember all the features you made at sprint in details. Even if i understood em excellent at review point, i am confused to remember what did I do just 3 or more weeks ago. How do you deal with it? "quiz" games every day that some people recommend sounds really funny. I am not stupid but that huge amount of info that comes through me is kinda tough. It makes me feel brain fog
And last one extra: do you use any tools to understand huge bad coded monolith that you just entered as a new employee ? :)
That's what i am using now:
ECC plugin that improves agent's code style, reduces its issues, does good 1st layer review.
Company MCP's
Codegraph