not much happened today

**Anthropic's Mythos/Opus cycle** sparked mixed reactions with praise for **Claude Mythos**'s one-shot workflows and concerns over **Opus 4.8** benchmark regressions. **Opus 4.7** showed strong chemistry task performance, "making Claude a chemist." **Sakana AI** launched an **RSI Lab** focusing on recursive self-improvement under compute constraints, marking RSI as a formal research program. New benchmarks like **Agents' Last Exam (ALE)** and **SWE-Marathon** test agents on long-horizon, economically meaningful tasks, revealing low pass rates and coherence challenges. Princeton's ICML 2026 paper found models like **GPT 5.5**, **Gemini 3.1 Pro / 3.5 Flash**, and **Claude Opus 4.7** still lack meaningful reliability improvements. Tooling trends favor RL-environment-style frameworks for agent evaluation, exemplified by Meta's **OpenEnv**.