Releases Claude Code v2.1.284 Public — Claude Sonnet 5.5 added as default model and various stability improvements
News Anthropic releases Claude Sonnet 5.5: faster and cheaper per task while rivaling Opus 5.5 performance
PLUS ULTRA Anthropic Unveils Claude Opus 5.5 with Enhanced Performance and 40% Lower Operational Costs
News Research Finds AI Coding Agent "Harnesses" Significantly Impact Cost, While Contribution to Success Rate Remains Limited
News Cognition Unveils Fusion: A Dual-Model Harness to Maximize AI Agent Performance and Cost-Efficiency