The Shift from Chatbots to Long-Horizon Agents
In 2023 a chatbot answered a question in one turn. In 2026 a frontier model routinely runs minutes to hours on a single task. METR's Time Horizon 1.1 benchmark (January 2026) puts Claude Opus 4.6 at 14+ hours of expert work at 50% reliability. The horizon has been doubling roughly every seven months since GPT-2. Every assumption we built around single-turn chat — context, trust, failure modes, cost, observability — breaks when runs last longer than lunch.
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