Auto-compaction triggers at 3% context usage despite DISABLE_AUTO_COMPACT=1

Bug Description

Auto-compaction (Recombobulating) triggers at the very start of a conversation when context usage is only ~3%, despite DISABLE_AUTO_COMPACT=1 being explicitly set.

Environment

• Claude Code version: v2.1.89
• Model: Opus 4.6 (1M context)
• Platform: macOS (Darwin 25.3.0)
• Shell: zsh
• Plan: Claude Enterprise

Configuration

~/.claude/settings.json has:

{
  "env": {
    "DISABLE_AUTO_COMPACT": "1"
  }
}

Steps to Reproduce

1. Set DISABLE_AUTO_COMPACT=1 in settings.json under env
2. Open a Claude Code session (or resume one)
3. Context usage is at ~3%
4. Auto-compaction ("Recombobulating...") triggers anyway, taking ~1m 10s and compressing to 8.7k tokens
5. All prior context is lost

Expected Behavior

• Auto-compaction should NOT trigger when DISABLE_AUTO_COMPACT=1 is set
• Even if the env var were not set, compaction should not trigger at 3% context usage (docs say default threshold is ~95%)

Actual Behavior

• Recombobulating triggered at 3% context usage
• Took 1m 10s, compressed everything down to 8.7k tokens
• All previous conversation context was lost

Additional Context

• Multiple Claude Code tabs were open simultaneously (4 sessions)
• This may be related to session resume behavior rather than a fresh session
• The DISABLE_AUTO_COMPACT env var appears to not be respected when set via settings.json env field