[BUG] Context blocked despite 31% free space

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?

60k tokens locked

What Should Happen?

Environment:

• Model: claude-opus-4-5-20251101
• Context window: 200k tokens
• Platform: Claude Code (terminal)

Description:
At 0% context in console with automatic compactation disabled, Claude Code shows "Context limit reached" and suggests /compact or /clear to continue.

However, the /context Usage panel shows 63k tokens free (31.3% of the 200k window).

Expected behavior:
With 31.3% free context, the session should not be blocked.

Actual behavior:
Session is blocked with "bypass permissions on" state, unable to continue despite available context space.

Breakdown shown:

• Messages: 93.5k tokens (46.8%)
• System tools: 16.7k tokens (8.3%)
• Memory files: 12.7k tokens (6.3%)
• MCP tools: 7.6k tokens (3.8%)
• System prompt: 3.9k tokens (1.9%)
• Compact buffer: 3.0k tokens (1.5%)
• Skills: 86 tokens (0.0%)
• Free space: 63k (31.3%)

Also, 200k tokens context window is INSUFFICIENT for MAX x20 users.

Error Messages/Logs

Steps to Reproduce

Just chat until you find 60k tokens are locked

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.12 (Claude Code)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

_No response_