Anthropic Publishes Harness Design Guide: Context Anxiety, GAN-Inspired Evaluator Architecture, and Compaction Strategies

r/ClaudeAI / Anthropic Engineering Blog·high signal

Anthropic's engineering blog details how they handle long-running Claude tasks, revealing that Sonnet 4.5 exhibited 'context anxiety' severe enough to require full context resets, while Opus 4.5 eliminated this, allowing continuous sessions with automatic compaction. The harness uses a GAN-inspired architecture separating Generator from Evaluator across four criteria (design quality, originality, craft, functionality). 578 upvotes on r/ClaudeAI.