Claude Code 2.1.307 Update Drops Haiku 3.5, Tweaks System Prompts

Claude Code 2.1.307 arrives just 18 hours after the previous release, removing claude-haiku-3.5 and cleaning up hook guidance. The update brings 31 tool prompts, with system prompts now taking up 57.5%.

2026-10-22 ~ 2026-10-22 · 2 related posts

• Claude Code 2.1.307 system prompt diff reveals cleaned-up hook guidance, 31 prompt files — ClaudeCodeLog · 2026-10-22
• Claude Code 2.1.307 drops Haiku 3.5, system prompt tokens jump 7.5% in 18 hours — ClaudeCodeLog · 2026-10-22