Deep Dives · Every Monday
Models & Agentic
Mistral Large 4's open weights (1T total, about 52B active, 1M context) arrive with mostly self-reported benchmarks; the week's building block is the eval set, calibrated judge and trace that turn those claims into a go/no-go.
Models & Agentic
Anthropic's 2026-10-21 API version rejects citations on user-message text blocks, which hits RAG code that replays retrieved chunks; and the retrieval stack worth defending is hybrid search, contextual chunks and a reranker, measured on your own labelled set.
Models & Agentic
Managed Agents can now let the model write a program that fans out up to 1,000 agents, which blurs the workflow-vs-agent line and moves the interesting design question to who approves the plan.
Models & Agentic
Opus 5.5 and Sonnet 5.5 return a 400 on tool_choice any/tool; the replacement is auto plus strict tool use, which changes how you design the agent loop's guarantees.