Anthropic admits to have made hosted models more stupid, proving the importance of open weight, local models

TL;DR: On March 4, we changed Claude Code's default reasoning effort from high to medium to reduce the very long latency - enough to make the UI appear frozen - some users were seeing in high mode. This was the wrong tradeoff. We reverted this change on April 7 after users told us they'd prefer to default to higher intelligence and opt into lower effort for simple tasks. This impacted Sonnet 4.6, Opus 4.6, and Opus 4.7. On March 26, we shipped a change to clear Claude's older thinking from sessions that had been idle for over an hour, to reduce latency when users resumed those sessions.