[BUG] Continuing from a session limit hit causes 45% of immediate quota usage (Fable 5.1)

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

When I hit the limits with Fable 5.1 and I have the auto-resume feature on, even asking a simple question causes immediate burn of ~half of the quota.

I assume this has something to do with cache being automatically invalidated after 5 hours of wait and this causing high usage; still it's very frustrating to wait 5 hours just to lose most of the quota immediately.

<img width="994" height="1280" alt="Image" src="https://github.com/user-attachments/assets/0d35abdb-6e81-496f-a3a7-74aff4d02e2f" />

What Should Happen?

If this is indeed a cache issue Claude code should probably warn the user and ask if they want an auto-compacting before execution, this could save a lot of usage.

Error Messages/Logs

Steps to Reproduce

1) Have a long session that uses Fable 5.1 on a Max plan ~500-600K tokens
2) Hit the quota
3) Prepare & send a simple message like "stop whatever you were doing and give me a short wrap up message, make sure not to burn any token"
4) Wait and observe most of the quota disappear

Claude Model

Other

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

2.1.263

Platform

Other

Operating System

Ubuntu/Debian Linux

Terminal/Shell

Other

Additional Information

_No response_