[BUG] "Error compacting conversation" causes Session Freeze (cannot save work or context)

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

Summary

When the "Error compacting conversation" message appears during a session, Claude Code becomes completely unresponsive to user input, requiring repeated Ctrl+C interrupts to temporarily recover. The session enters a freeze-recovery cycle that eventually requires force termination.

Environment

• Claude Code Version: [Current version as of 2026-02-02]
• OS: Windows (WSL2)
• Session Size: ~2,674 messages, 13+ hours of active use

Steps to Reproduce

1. Start a Claude Code session
2. Work continuously for extended period (multiple hours)
3. Allow conversation to grow to ~2,000+ messages
4. Session displays: "Error compacting conversation"
5. Attempt any user input

Expected Behavior

• Session should either successfully compact the conversation, or
• Display a clear error message and allow user to save work, or
• Gracefully degrade to a read-only mode

Actual Behavior

Initial symptom: "Error compacting conversation" message appears

Freeze pattern:

1. User types command and presses Enter
2. Complete freeze - no response, no output, prompt doesn't return
3. User presses Ctrl+C → prompt briefly returns
4. User attempts another command
5. Immediate freeze again
6. Cycle repeats (Ctrl+C → brief recovery → freeze)

Timeline example from affected session:

[22:22:26] User command submitted → NO RESPONSE → Ctrl+C interrupt
[22:22:59] User command submitted → NO RESPONSE → Ctrl+C interrupt
[22:23:44] User command submitted → NO RESPONSE → Ctrl+C interrupt
[22:24:18] User command submitted → NO RESPONSE → Ctrl+C interrupt
[22:24:50] User command submitted → NO RESPONSE → Ctrl+C interrupt
[22:30:38] Session force-terminated (unrecoverable)

Impact

• Severity: CRITICAL
• Session becomes unusable
• No graceful way to save work or exit
• Forces user to terminate Claude Code process
• Loss of session context
• Cannot execute any commands during freeze state

Suggested Improvements

1. Graceful degradation: If compaction fails, continue in degraded mode rather than freezing
2. Timeout handling: Detect frozen state and offer recovery options
3. Pre-compaction safety: Save session state before attempting compaction
4. Proactive warnings: Alert users approaching message limits (e.g., at 1500, 2000 messages)
5. Recovery mode: Offer read-only mode to allow users to save work when compaction fails

Additional Notes

• Ctrl+C interrupts provide only temporary 1-2 second recovery windows
• Issue appears related to session size/message count
• No data corruption observed after force termination
• Session history remains accessible after restart

Workaround

Currently no workaround available once freeze cycle begins. Only option is to force-terminate Claude Code process and restart.

What Should Happen?

Expected Behavior

• Session should either successfully compact the conversation, or
• Display a clear error message and allow user to save work, or
• Gracefully degrade to a read-only mode

Suggested Improvements

1. Graceful degradation: If compaction fails, continue in degraded mode rather than freezing
2. Timeout handling: Detect frozen state and offer recovery options
3. Pre-compaction safety: Save session state before attempting compaction
4. Proactive warnings: Alert users approaching message limits (e.g., at 1500, 2000 messages)
5. Recovery mode: Offer read-only mode to allow users to save work when compaction fails

Error Messages/Logs

**Initial symptom**: "Error compacting conversation" message appears

**Freeze pattern**:
1. User types command and presses Enter
2. **Complete freeze** - no response, no output, prompt doesn't return
3. User presses Ctrl+C → prompt briefly returns
4. User attempts another command
5. **Immediate freeze again**
6. Cycle repeats (Ctrl+C → brief recovery → freeze)

**Timeline example from affected session**:

[22:22:26] User command submitted → NO RESPONSE → Ctrl+C interrupt
[22:22:59] User command submitted → NO RESPONSE → Ctrl+C interrupt
[22:23:44] User command submitted → NO RESPONSE → Ctrl+C interrupt
[22:24:18] User command submitted → NO RESPONSE → Ctrl+C interrupt
[22:24:50] User command submitted → NO RESPONSE → Ctrl+C interrupt
[22:30:38] Session force-terminated (unrecoverable)

Steps to Reproduce

Steps to Reproduce

1. Start a Claude Code session
2. Work continuously for extended period (multiple hours)
3. Allow conversation to grow to ~2,000+ messages
4. Session displays: "Error compacting conversation"
5. Attempt any user input

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.29

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

WSL (Windows Subsystem for Linux)

Additional Information

Environment

• Claude Code Version: [Current version as of 2026-02-02]
• OS: Windows (WSL2)
• Session Size: ~2,674 messages, 13+ hours of active use

Impact

• Severity: CRITICAL
• Session becomes unusable
• No graceful way to save work or exit
• Forces user to terminate Claude Code process
• Loss of session context
• Cannot execute any commands during freeze state

Additional Notes

• Ctrl+C interrupts provide only temporary 1-2 second recovery windows
• Issue appears related to session size/message count
• No data corruption observed after force termination
• Session history remains accessible after restart

Workaround

Currently no workaround available once freeze cycle begins. Only option is to force-terminate Claude Code process and restart.