[BUG] `/context` do not respect `--system-prompt` flag

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?

Description

When I run claude --system-prompt "Answer with ALL CAPS" the /context command shows that System Prompt is still usual 2.4K token.

What Should Happen?

/context should show actual size when --system-prompt is used.

Steps to Reproduce

1. Run claude --system-prompt "Answer with ALL CAPS"
2. Run /context in TUI

Claude Model

Sonnet (default)

Is this a regression?

I don't know

Claude Code Version

2.0.35

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)