[BUG] Restarting claude with --resume clears out context and allows sessions to continue longer

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?

I can consistently extend claude's context window by existing out of claude and using --resume. This happens on the latest production claude version.

Here's what a session looks like before the ctl-c, claude --resume:
<img width="662" height="244" alt="Image" src="https://github.com/user-attachments/assets/4d496969-6757-4230-9027-c979b8f2e1cb" />

Here's after:
<img width="681" height="248" alt="Image" src="https://github.com/user-attachments/assets/c0033f9d-078f-4beb-b556-a11d3d96fbc7" />

What Should Happen?

Claude seems no dumber after the ctl-c loop, so claude should drop whatever context that is lost by doing ctl-c instead of jumping to /compact.

Error Messages/Logs

Steps to Reproduce

1. Use claude a lot
2. See a few percent left of context
3. Run /context
4. ctl -c
5. claude --resume
6. Run /context

The second time of running /context, the context will be way lower.

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.0.25

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_