Task output file in /private/tmp grows unbounded (350GB in single session)

Bug Description

A single task output file under /private/tmp/claude-501/<project>/<session>/tasks/ grew to 350GB during one conversation session, filling the disk to 99% capacity.

Environment

• Claude Code version: 2.1.74
• OS: macOS (Darwin 25.3.0, APFS 460GB disk)
• Platform: VSCode extension

Steps to Reproduce

1. Have a long conversation session with many sub-agent (Agent tool) invocations
2. The file /private/tmp/claude-501/<project>/<session-id>/tasks/<task-id>.output accumulates all sub-agent outputs via append
3. No size cap or rotation exists on this file

What Happened

• Session ID: 884644d8-bdb0-491d-8c84-363b330c3317
• File: b6rs5lm1n.output
• Size: 376,142,184,393 bytes (350GB)
• Lines: 17,316,244
• The file concatenates sub-agent outputs with === <agent-id>.output === delimiters
• First 10MB alone contained 171 sub-agent output sections
• Estimated total: ~6 million sub-agent output entries
• Created during a single day of conversation (Mar 12, 2026)

Impact

• Disk filled to 99% (405GB/460GB used), macOS showed storage full warning
• User could not identify the cause without deep investigation into /private/tmp
• File was still held open by processes even after deletion (required lsof + kill to reclaim space)

Expected Behavior

• Task output files should have a size cap or rotation policy
• Old/completed task outputs should be cleaned up when a session ends
• At minimum, warn the user when tmp storage exceeds a threshold

Workaround

# Find large task output files
du -sh /private/tmp/claude-501/*/tasks/*.output | sort -rh | head

# Delete and kill any processes holding the file
rm <file>
lsof | grep <filename>  # find PID
kill <PID>

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