Background task output file grew to 459GB filling disk

Bug Report

Description

A subagent background task produced a single output file that grew to 459GB, filling the entire disk. The file was located at:

/private/tmp/claude-501/-Users-<user>-Development-<project>/tasks/bjy1z7k8u.output

What happened

The file appears to be a concatenation of all subagent .output symlink targets — it starts with === a0031d70159a27d1c.output === followed by JSONL conversation logs. It seems like a task that was meant to aggregate/list subagent outputs ran without any size limit and kept writing indefinitely.

The file contained JSONL subagent conversation logs (tool calls, responses, etc.)

Impact

• Filled 459GB of a 926GB disk (50% of total disk)
• macOS reported disk full warnings
• Docker builds and other operations failed due to lack of space

Environment

• Claude Code version: 2.1.72 (at time of creation, based on file contents)
• OS: macOS Darwin 25.3.0 (Apple Silicon)
• The file was created around 2026-03-30

Expected behavior

Background task output files should have a size cap or automatic cleanup. A single temp file should never be allowed to grow unbounded.

Suggested fixes

1. Enforce a max file size for background task output files (e.g., 100MB)
2. Rotate or truncate output files when they exceed a threshold
3. Add periodic cleanup of stale temp files in /private/tmp/claude-*
4. Warn the user when temp directory usage exceeds a configurable limit