Repository navigation
Session JSONL files grow to multi-GB size due to bloated "progress" entries #18905
Description
Preflight Checklist
- I have searched existing issues and this hasn't been reported yet
- This is a single bug report (please file separate reports for different bugs)
- I am using the latest version of Claude Code
What's Wrong?
Session JSONL files can grow to extreme sizes (5+ GB) due to progress type entries accumulating large amounts of duplicated data.
In my case, a session file grew to 5.27 GB with 1,739 "progress" entries averaging ~3 MB each. The actual conversation (user/assistant messages) was only 0.67 MB.
This caused:
- Session disappeared from Past Conversations
- Claude Code became unresponsive
- ~5 GB of unexpected disk usage
What Should Happen?
Progress entries should be lightweight streaming updates, not accumulate the full conversation context repeatedly. A typical session should remain under 10 MB.
Error Messages/Logs
No explicit error - the session simply stopped appearing in Past Conversations.
File analysis showed:
| Message Type | Count | Size |
|--------------|-------|------|
| progress | 1,739 | 5,396 MB (99.6%) |
| user | 56 | 0.39 MB |
| assistant | 110 | 0.25 MB |Steps to Reproduce
- Start a conversation using multiple sub-agents via the Task tool (e.g., AWS Infrastructure agent + Datadog agent in parallel)
- Have a lengthy back-and-forth troubleshooting session
- Check session file size in: ~/.claude/projects//
- Observe progress entries growing to MB+ sizes each
Claude Model
Opus
Is this a regression?
I don't know
Last Working Version
No response
Claude Code Version
2.1.9
Platform
Anthropic API
Operating System
Windows
Terminal/Shell
VS Code integrated terminal
Additional Information
Workaround: Filtering out "progress" type entries from the JSONL file restored functionality:
- Before: 5.27 GB (1,927 lines)
- After: 0.67 MB (188 lines)
The session involved parallel Task tool calls with sub-agents investigating a performance issue. This may be related to how agent progress is logged/accumulated.
Possibly related to #9890, #10107, #10505 - but those focus on FileHistory/.claude.json while this bug is specifically about "progress" type entries in session JSONL files accumulating context.
Activity
github-actions commentedon Jan 18, 2026
Found 2 possible duplicate issues:
This issue will be automatically closed as a duplicate in 3 days.
🤖 Generated with Claude Code
kylesnowschwartz commentedon Jan 21, 2026
Hit this on macOS with v2.1.12. Session reached 4.3GB - 3.4GB main transcript + 860MB subagent log. 105 lines in the JSONL, with individual progress entries reaching 934 million characters (~900MB each). Trace trap on startup until I moved the session out of ~/.claude/projects/.
junaidtitan commentedon Feb 10, 2026
Had the same issue — session files ballooning to multi-GB from progress tick entries. In my case it was thousands of progress entries averaging ~3MB each while the actual conversation was under 1MB. Pure bloat.
Built Cozempic to deal with this. The
progress-collapsestrategy targets exactly this — it collapses consecutive progress tick messages down to a single representative entry. On sessions like yours this alone can reclaim 40-50% of file size.cozempic initwires a guard daemon that auto-starts on every session and continuously prunes this bloat before it accumulates. You can also treat an existing bloated session:Would really appreciate if you could test this on one of your bloated sessions and let me know if it helps. If
progress-collapsedoesn't catch all the patterns in your case, I'd like to investigate further and add additional fixes.github-actions commentedon Mar 11, 2026
Closing for now — inactive for too long. Please open a new issue if this is still relevant.
github-actions commentedon Mar 19, 2026
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.