[BUG] Memory Leak from Unbounded Session File Growth

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?

Version: Claude Code 2.1.17
OS: macOS 15.4.1 (24E263)
Platform: darwin

Claude added plenty of its own opinions in this report, I only cleared a few out.

Summary

Claude Code exhibits memory leak behavior where session files (.jsonl) grow unbounded over long conversations, causing processes to consume 5-6GB of RAM and experience severe performance degradation (multi-minute
delays between responses before tokens are seen to be consumed).

Evidence

1. Excessive Memory Usage

• Claude processes observed using 5.7GB RAM (one instance)
• Current active sessions: 839MB-1.2GB each

1. Massive Session Files

• Projects directory: 604MB total
• 19 session files over 5MB each
• Largest session file: 195MB (1,193 snapshots)
• Average snapshot size: ~164KB per entry
• Multiple sessions: 57MB, 28MB, 26MB, 25MB, 24MB, 22MB (multiple), 21MB, etc.

1. Performance Impact

• Multi-minute delays with no token generation ("thinking" with no progress)
• Pauses after command output completion lasting minutes
• Performance improved only after high-memory process died/crashed

Expected Behavior

• Session files should be pruned/rotated automatically when exceeding size thresholds
• Memory usage should remain reasonable even for long conversations
• /clear command should actually clean up session storage, not just the UI
• Old session snapshots should be garbage collected

Actual Behavior

• Session .jsonl files grow indefinitely with no automatic cleanup
• Each snapshot stores ~164KB of data (seems excessive)
• Memory usage scales with session file size
• Processes eventually consume 5-6GB RAM and become unresponsive
• /clear only clears conversation view, not underlying session data

Workaround

Close any running claude processes. Can also try removing files as below but don't have a reproduction to know whether this helped.

Delete large session files (loses history)

find ~/.claude/projects -name "*.jsonl" -size +10M -delete

Clean file history cache

rm -rf ~/.claude/file-history/*

Additional Context

• Issue occurs across multiple projects (monorepo workflows)
• Not related to heavy data processing - just normal CLI usage
• Performance degradation is gradual over weeks of use
• No visible indication to user that session files are growing out of control

What Should Happen?

Proposed Solutions

1. Automatic session pruning: Delete or archive sessions older than N days
2. Size-based rotation: When session file exceeds threshold (e.g., 5MB), start new session
3. Snapshot optimization: Reduce snapshot size from 164KB to something more reasonable
4. Memory management: Properly release memory after loading session files
5. Manual cleanup command: Add /cleanup-sessions or similar

Error Messages/Logs

Steps to Reproduce

Steps to Reproduce

1. Use Claude Code regularly over several weeks
2. Have long-running conversations (with occasional /clear commands)
3. Work across multiple projects
4. Monitor memory usage: ps aux | grep claude
5. Check session file sizes: find ~/.claude/projects -name "*.jsonl" -size +5M

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.17

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_