[BUG] Statusline doesn't refresh after /compact

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?

Statusline continues showing pre-compact context_window values (or resets to blank/0.0k, depending on the statusline script) after running /compact. /compact completion itself doesn't trigger a refresh.

Referenced in https://github.com/anthropics/claude-code/issues/35816 which was closed for inactivity.

What Should Happen?

The statusline should show an updated context usage number after compacting.

Error Messages/Logs

Steps to Reproduce

1. Configure a custom statusline that displays context_window.used_percentage
2. Build up context usage in a session
3. Run /compact
4. Observe the statusline — it still shows the pre-compact value until the next prompt/assistant turn

Claude Model

Not sure / Multiple models

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

2.1.232

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

This has been reported repeatedly and auto-closed as duplicates each time, but the underlying gap was never fixed. The canonical thread (#35816) is now locked due to inactivity, so filing fresh per its own auto-lock instructions. Related: #35816, #57541, #50688, #19669, #29651, #58268.