Cursor announced that Claude Fable 5.1 is now available. It is the most capable model they have run on CursorBench 3.2, scoring 73.4% at max effort, and is especially skilled at verifying its own work on difficult coding tasks.
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Elon Musk said Grok 4.8 is a 2.5-trillion-parameter model trained on xAI's new C++ software stack. Training wraps this week, then reinforcement learning begins. In a follow-up he said Grok 4.7 should be roughly on par with Opus 5.0, Grok 4.8 a noticeable improvement, Grok 4.9 likely Astra/Fable class, and Grok 5 possibly better than anything.
Elon Musk confirmed Grok is available in Microsoft Copilot after Microsoft CEO Satya Nadella said Copilot is adding more model choice and welcomed Grok.
Elon Musk said Grok 4.7 still needs a few more days. He suggested RL may have penalized response length too much, causing the model to give up too early on hard tasks it can do and to check its work insufficiently.
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