[BUG] Aggressive clearing of conversation history at ~2k tokens on Opus 4.6 (1M context) v2.1.89

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?

• v2.1.89, Opus 4.6 (1M context), Claude Max
• Fresh conversation, not near any limit
• Conversation history disappears while actively working, only "Simmering" status visible
• Screenshot shows ↓ 2.0k tokens — nowhere near the 1M limit (https://i.imgur.com/smV2vQB.png)
• Possibly a regression of the fixes from v2.1.21 / v2.1.75 / v2.1.88

What Should Happen?

Conversation history should remain visible and scrollable for the entire session and not get auto cleared at ~2.0k tokens on a 1M context window.

Error Messages/Logs

No error messages displayed. No dedicated log files found in ~/.claude/. The compaction happens silently — conversation history simply disappears with no warning or error. The only indicator is the "Simmering" status showing ↓ 2.0k tokens.

Steps to Reproduce

1. Run Claude Code v2.1.89 (CLI in terminal)
2. Model: Opus 4.6 (1M context), Claude Max subscription
3. Platform: Linux (WSL2 on Windows)
4. Start a new conversation (claude or /clear)
5. Perform a multi-turn session with tool-heavy operations (running shell scripts with large output, spawning subagents, reading files)
6. After ~5-6 turns, conversation history above the current exchange is compacted away
7. The ↓ token counter shows ~2.0k tokens — far below the 1M context limit
8. Cannot scroll up to see earlier messages

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

Unknown

Claude Code Version

2.1.89

Platform

Anthropic Console (Claude Max)

Operating System

Windows

Terminal/Shell

WSL (Windows Subsystem for Linux)

Additional Information

Last known working version was around 2.1.86. The issue started appearing recently around v2.1.88-2.1.89.