River AI raises $1.1B seed round for personal trainable agents

River AI, a 2-month-old startup founded by ex-xAI co-founder Babuschkin, raised a $1.1B seed round led by General Catalyst. The company aims to rebuild the AI stack for personal, trainable agents rather than worker replacement, offering RL and LoRA fine-tuning on open models. LoRA customization takes 15-20 min with 4x cost efficiency; plans for custom silicon. This signals continued investor appetite for agentic AI infrastructure and could shift how enterprises approach model ownership.