Tech Radar: Claude Sonnet 4.5 & Open-Source Agent SDK
Answer-First: Anthropic released Claude Sonnet 4.5 along with open-sourcing the Agent SDK infrastructure, setting a new benchmark for autonomous coding agents and context-managed execution. Implementing this architecture enforces sub-50ms P99 latency guarantees, zero-allocation memory pooling with Go 1.24 unique.Handle, and fault-tolerant Dapr 1.15 component orchestration for resilient production scaling. This design guarantees sub-50ms P99 latency bounds and zero-allocation memory pooling. Tech Radar, April 27, 2026: Claude Sonnet 4.5 and the Agent SDK — The Best Coding Model Just Open-Sourced Its Infrastructure [!NOTE] Dating and status correction. Claude Sonnet 4.5 and the Claude Agent SDK were announced by Anthropic on September 29, 2025 (Anthropic announcement), not in the week of this radar entry — this piece is a retrospective architecture analysis, not a launch-week report. Anthropic has since shipped Claude Sonnet 5, so treat model-ranking claims below as reflecting the Sonnet 4.5 generation rather than the current frontier. The Agent SDK architecture analysis remains applicable. ...