How to make a Claude Code subagent compact earlier with autoCompactWindow

Since Claude Code v2.1.296 you can put autoCompactWindow in a subagent definition, so the subagent auto-compacts on a smaller window than the main conversation.

Add it to the frontmatter of the subagent file under .claude/agents/.

---
name: explorer
description: Skims the codebase to find relevant files
autoCompactWindow: 200000
---

The same key works in definitions passed with --agents.

For the main conversation, the autoCompactWindow setting and the CLAUDE_CODE_AUTO_COMPACT_WINDOW environment variable take a plain token count from 100000 to 1000000. Writing 500k reads as 500 and clamps to the minimum. The changelog doesn't give a range for the subagent key.