Claude Code v2.1.299: idle long conversations get compacted before the cache expires
What is it?
In the terminal, a conversation over 200K tokens that sits idle for about 54 minutes now gets compacted before its one-hour prompt cache (the stored prefix that saves recomputing the same context) expires. Change the token threshold with CLAUDE_CODE_IDLE_COMPACT_MIN_TOKENS, or turn it off with "idleCompaction": false in settings.json. A new CLAUDE_CODE_DISABLE_FILE_MENTIONS variable makes @ file mentions pass only the path instead of the contents.
npm install -g @anthropic-ai/claude-code@2.1.299Why does it matter?
Come back from lunch to a long session and you no longer pay to reprocess the whole conversation. It also closes a few permission holes: an allow rule for mcp__a no longer covers a server named a__b, macOS sandbox deny rules now hold through symlinks, and plan mode no longer runs writes that a PreToolUse hook approved.
Maturity
GAStable release. Idle compaction only runs in the terminal, and its settings are read by v2.1.290 or later.
How to track it
- Default changes: subscribe to GitHub Releases to see if the 200K-token or 54-minute thresholds move.
- Coverage: check the Claude Code docs changelog for idle compaction landing in the desktop app or IDE extensions.
- Security fixes: if your MCP allow rules lean on broad prefixes, review them now.