[BUG] Autocompact not triggering at high context usage (90%+)

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?

Autocompact/context summarization never triggers regardless of context usage percentage. Context climbs to 90%, 95%, 100%+ and conversation continues indefinitely without ever compacting.

What Should Happen?

Context should automatically compact/summarize around 80-90% to prevent unbounded growth.

Error Messages/Logs

None

Steps to Reproduce

1. Start a new conversation
2. Perform multiple file reads/edits (normal development work)
3. Watch context percentage climb to 90%, 92%, 95%+
4. Observe: no compaction occurs
5. Eventually hits 100%

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.3

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

VS Code integrated terminal

Additional Information

Happens in normal conversations (not during subagent execution)
Active tool use (Read, Edit, Write) throughout - should provide opportunities to compact between turns
No explicit setting to enable/disable autocompact visible in ~/.claude.json