[BUG] Conversation compaction loses entire history, ctrl+e unresponsive

[ThatDragonOverThere]

Description

After conversation compaction, the entire conversation history is lost. Only the compact summary notes remain visible.

Steps to Reproduce

1. Work on a task until compaction triggers
2. After compaction completes, conversation shows only compact notes
3. Previous messages/task context completely gone

Expected Behavior

• Compacted conversation should preserve context
• Ctrl+O should restore previous messages
• Ctrl+E should show full transcript

Actual Behavior

• Entire last task forgotten after compaction
• Ctrl+O only shows compact notes (not full history)
• Ctrl+E does not respond / no full transcript available
• Conversation effectively lost

Impact

Task progress lost, must restart work from scratch.

Environment

• Platform: Windows
• Application: Claude Code CLI

[github-actions]

Found 3 possible duplicate issues:

1. [BUG] Scrollback History after compacting CTRL+R and CTRL+E blank screen unresponsive #7424
2. [BUG] After compaction the terminal resets and i cannot scroll up and see what all were discussed, changed and done. #13446
3. Compaction clears screen - can't scroll up to see previous context #18204

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🤖 Generated with Claude Code

[ThatDragonOverThere]

This is NOT a duplicate of the scroll buffer issues.

Key difference: The suggested duplicates (#7424, #13446, #18204) describe losing the ability to scroll up in the terminal after compaction.

This issue describes: After compaction, ctrl+e (conversation history) shows nothing at all - the entire conversation history appears to be deleted, not just the terminal scroll buffer. The data itself is gone from the session, not just hidden from view.

This is a more severe bug - complete data loss vs. visual scroll buffer clearing.

[ThatDragonOverThere]

Reproduction - Jan 23, 2026:

After compaction, Claude Desktop stopped responding again. Was in the middle of:

• Verifying script relationships (overnight_analysis_pipeline.py calling unsupervised_pattern_discovery.py)
• Validating IQFeed symbol references

Session showed "14 steps" and "Verifying script relationships and validating symbol references" then froze with just "F read_file" visible.

Same pattern as original report:

• Compaction triggers
• UI becomes unresponsive
• Work in progress is lost
• Must restart session

[ThatDragonOverThere]

Additional symptom from same incident:

After the freeze/compaction, Claude Desktop responded with:

• "Yes, I'm here! Sorry about that - I was trying to access files but ran into path issues."
• "Based on the compacted summary, we were discussing corrections to the CLAUDE.md documentation"

This shows Claude:

1. Lost the actual conversation context
2. Is reconstructing from compacted notes (incorrectly)
3. Gives generic "I'm here" responses instead of continuing work

The compaction is not just freezing - it's corrupting/losing the conversation state, forcing Claude to guess what was being discussed.

[ThatDragonOverThere]

Additional impact discovered:

The compaction bug also caused file truncation. CLAUDE.md was truncated from ~860 lines to 424 lines - losing the entire bug tracker section and other critical documentation.

This suggests the compaction issue isn't just losing conversation context - it may be corrupting file operations in progress, resulting in partial writes or truncated files.

[ThatDragonOverThere]

New error observed: "max compactions exceeded" flashed briefly before the compaction failure.

This suggests there may be a hard limit on compaction attempts that's being hit, causing the cascading failures (history loss, ctrl+e unresponsive, etc.).

[ThatDragonOverThere]

Another compaction error observed: "NO compactable messages available"

This appeared in the same session where "max compactions exceeded" was seen. Suggests the compaction system is hitting multiple failure modes.