Latent Space daily roundup covers GPT-6.1 Sol, Sonnet 5.5, agent harnesses, and eval integrity debates

This Latent Space AINews roundup compiles a weekend's AI news from Twitter and Reddit rather than a single announcement. It covers OpenAI's GPT-6.1 Sol pricing and Agent Arena placement, Anthropic's Sonnet 5.5 debut, Meta's open-sourced Muse hardware firmware, and several research and benchmark items, many reported with unverified claims.