[BUG] "Context limit reached" triggers at 27% usage (68.9% free space) — regression in 2.1.33

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?

Claude Code displays "Context limit reached · /compact or /clear to continue" despite /context reporting only 27% usage (55k/200k tokens) with 138k tokens (68.9%) free. This is a regression introduced in 2.1.33 — reverting to 2.1.32 resolves the issue.

What Should Happen?

User should be able to continue

Error Messages/Logs

Steps to Reproduce

1. Start a Claude Code session using claude-opus-4-6
2. Work through a normal conversation (in my case, asking about test files in a monorepo)
3. After a short interaction, "Context limit reached" appears
4. Run /context — shows only 27% usage with 68.9% free space

/context Output

Context Usage
  claude-opus-4-6 · 55k/200k tokens (27%)

  Estimated usage by category
    System prompt: 3.7k tokens (1.8%)
    System tools: 25.2k tokens (12.6%)
    MCP tools: 5.4k tokens (2.7%)
    Custom agents: 3.5k tokens (1.7%)
    Memory files: 1.3k tokens (0.6%)
    Skills: 572 tokens (0.3%)
    Messages: 19.4k tokens (9.7%)
    Compact buffer: 3k tokens (1.5%)
    Free space: 138k (68.9%)

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

3.1.32

Claude Code Version

2.1.37

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

• Claude Code version: 2.1.33+ (works correctly on 2.1.32)
• Model: claude-opus-4-6
• OS: macOS
• Setup: Nx monorepo project with MCP tools and custom agents configured