Prompt too long error persists when compact command fails despite CLAUDE_AUTOCOMPACT_PCT_OVERRIDE=60

[sircodes]

Description

When hitting context limits, the automatic compact command fails with a "prompt too long" error, even with CLAUDE_AUTOCOMPACT_PCT_OVERRIDE set to 60. The compaction itself seems to exceed the context window, creating a deadlock where you can't compact because the prompt is too long, but the prompt is too long because it can't compact.

Steps to Reproduce

1. Set environment variable CLAUDE_AUTOCOMPACT_PCT_OVERRIDE=60
2. Work in a session until context fills up
3. Auto-compact triggers (or manually run /compact)
4. Compact command itself fails with "prompt too long" message

Expected Behavior

The compact command should be able to summarize and reduce context even when nearing the context limit. Setting CLAUDE_AUTOCOMPACT_PCT_OVERRIDE=60 to trigger compaction earlier should prevent this scenario entirely.

Actual Behavior

Compact fails with a "prompt too long" error, leaving the session in an unrecoverable state where context is full and cannot be reduced.

Environment

• OS: Windows 10 (MSYS2/Git Bash)
• Claude Code: latest
• Model: claude-opus-4-6
• CLAUDE_AUTOCOMPACT_PCT_OVERRIDE=60

[github-actions]

Found 3 possible duplicate issues:

1. /compact fails with 'Conversation too long' when context limit is reached #23047
2. [Bug] Auto-Compact Failure Leaves Instance in Unrecoverable Context Limit State #24942
3. [BUG] Reaching context limit is not allowing to manual /compact at all #25620

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🤖 Generated with Claude Code

[sarob]

i have been getting these msg in prompts over the past couple of days

• Image base64 size (5.0 MB) exceeds API limit (5.0 MB). Please resize the image before sending.
• prompt is too long
• they are starting to impact my ability to work as I am regularly losing the conversation history. updating a plan markdown file is a workaround, but it is slowing me down.
• when I try to report these bugs, the Fin AI Agent regularly hallucinates and tries to get me to use non-existing methods to report bugs, e.g. use /doctor or /bug or /debug within claude code.
• when I ask for a human to help, I get a boilerplate we will email you and then nothing else. The communication stops. No more chat and no email that anything will happen.
• I like the claude code tooling, but this is a poor experience with little hope of being repaired.
• I am posting here as a last ditch option of getting any type of support

[junaidtitan]

Same issue here — even with AUTOCOMPACT_PCT_OVERRIDE set lower, the compact itself fails because the conversation is already too long. We worked around it with cozempic — it prunes the session JSONL directly (removes progress ticks, stale tool results, metadata bloat) so compact doesn't need to deal with an oversized conversation in the first place. Runs as a background guard with soft/hard thresholds.

pip install cozempic
cozempic init

Would be great if you could test it and let us know if it resolves the deadlock for you.

[sarob]

Since losing conversation history was a recurring problem for me, I built a bash dashboard to track all Claude Code operational files (CLAUDE.md, MEMORY.md, conversation logs) across projects. It helps you see what Claude knows per project and clean up old session logs.

Zero dependencies, single script: https://github.com/sarob/claude-ops

[github-actions]

Closing for now — inactive for too long. Please open a new issue if this is still relevant.

[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.