Claude Code 用 Opus 5.5 跑两轮会话被计费 39 美元，/usage 却显示 Haiku 承担主要推理

just ran a session and used opus 5.5 in claude code with "1 HR TTL SETTING" with API authentication(no max sub), since this was just one off session and i didnt want to buy 100 dollar max plan.

But OMG. THIS SESSION ENDED UP COSTING ME ALMOST 39 DOLLARS.

Few questions:

1. I was using haiku before i changed it to opus 5.5 for the actual work
2. But i didnt use /clear and changed from haiku to opus 5.5 (high effort with ultracode mode on)
3. Did the whole two turn session

Now, when i ran /usage i see haiku there and my earlier turns with haiku was definitely not this reasoning heavy where it ran 204 web searches. So this is definitely from my actual session where i changed the default model to opus 5.5. So why is haiku present at all, let alone carrying the whole reasoning part with 4.1m input and 204 web searches, etc, etc..... when i deliberately paid huge upfront cache write 1 hr ttl and ultracode mode on with opus.

I feel like i paid 39 dollars for haiku to carry main parts of this session and opus being just there to write its opinion on haikus work, instead of it doing all the work. THE FIRST TURN ANSWER WAS HOPELESSLY MEDIOCRE BTW

Any response would be helpful. thanks in advance for all the replies!!