Auto-compact firing at 16% context used

Bug

Auto-compact fired when the context bar showed 16% used — meaning 84% of the context window was still available. Compaction should not fire anywhere near that low.

Expected behavior

The context bar shows how much of the context window has been used. At 16% used, there is plenty of headroom. Auto-compact should fire near the upper threshold (~80%+ used), not at 16%.

Actual behavior

Auto-compact triggered mid-session at 16% used and the conversation was compressed without warning.

Environment

• Claude Code on macOS (Darwin 25.3.0)
• Model: claude-opus-4-7