CLAUDE_AUTOCOMPACT_PCT_OVERRIDE not triggering at configured threshold

[YebooLixoo]

Bug Description

CLAUDE_AUTOCOMPACT_PCT_OVERRIDE=55 is set as an environment variable but auto-compaction does not trigger at 55% context usage. The main session regularly exceeds the configured threshold without compacting — observed at 67% in one session and over 80% in another before compaction finally occurred.

Environment

• Claude Code version: 2.1.79
• Model: Claude Opus 4.6 (Max plan)
• OS: macOS (Darwin 23.5.0)
• Shell: zsh

Steps to Reproduce

1. Set export CLAUDE_AUTOCOMPACT_PCT_OVERRIDE=55 in ~/.zshrc
2. Verify the variable is loaded: echo $CLAUDE_AUTOCOMPACT_PCT_OVERRIDE → 55
3. Start a Claude Code session and use it until context exceeds 55%
4. Observe that auto-compaction does not trigger at 55%

Expected Behavior

Auto-compaction should trigger when context window usage reaches ~55%, as configured by CLAUDE_AUTOCOMPACT_PCT_OVERRIDE.

Actual Behavior

• Context reached 67% (see screenshot) without triggering auto-compaction
• In another session, context reached over 80% before auto-compaction finally fired
• The env var appears to be ignored for the main session

Screenshot

Context at 67% with no auto-compaction triggered:

Additional Context

• The env var is confirmed set in the shell environment
• CLAUDE_CODE_AUTO_COMPACT_WINDOW is not set (default)
• According to the docs, CLAUDE_AUTOCOMPACT_PCT_OVERRIDE should apply to both main conversations and subagents
• The HUD percentage comes from Claude Code's native used_percentage field, so the reported percentage should match what the compaction engine sees

[github-actions]

Found 1 possible duplicate issue:

1. CLAUDE_AUTOCOMPACT_PCT_OVERRIDE cannot raise threshold above default (~83%) #31806

This issue will be automatically closed as a duplicate in 3 days.

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🤖 Generated with Claude Code

[YebooLixoo]

This appears to be the same root cause as #18264 — CLAUDE_AUTOCOMPACT_PCT_OVERRIDE does not work as documented.

In my case, the override is set to 55 but auto-compaction does not trigger until well past that threshold (observed at 67% and 80%+). The env var appears to be ignored for the main session's compaction logic.

Related issues: #18152, #19018, #24856, #17292

[github-actions]

This issue has been automatically locked since it was closed and has not had any activity for 7 days. If you're experiencing a similar issue, please file a new issue and reference this one if it's relevant.