Two Claude Code releases in two days. Version 2.1.314 adds a setting, permissions.blockWritesOutsideWorkingDirectories. With it on, the Write, Edit and NotebookEdit tools refuse any path outside your working directories in every permission mode. The same release makes claude -p exit with code 1 when startup fails (it used to exit 0 with no output), and adds idle compaction in VS Code and the Desktop Code tab for conversations over 200K tokens.
Version 2.1.316 adds CLAUDE_CODE_SUBAGENT_EFFORT, which sets the effort level subagents use when nothing else names one, instead of inheriting the session's level. CLAUDE_CODE_DISABLE_ULTRATHINK turns the ultrathink keyword off. It also fixes --restricted sessions uploading files from outside the working directories when a Read allow rule covered them.
The date to note: fast mode for Opus 4.8 was deprecated on October 30 and will be removed on November 30. After that, fast mode requests on Opus 4.8 return an error instead of falling back to standard Opus 4.8. Anthropic's changelog says to move to Opus 5.5 to keep the speedup.