How Castform + Neon Beats Frontier Models on Price and Efficiency

Castform and Neon have partnered to enable RL post-training of small open-source models on proprietary enterprise data stored in Postgres. A 4B parameter model post-trained with Castform matched GPT-5.6 Sol on retrieval accuracy at 100x lower cost. The pipeline uses Neon's Lakebase Search extensions for corpus storage, synthetic data generation, and inference. Castform automates the RL training loop — generating question-answer pairs from existing documents, defining reward functions, and managing rollouts — without requiring ML or GPU expertise. Neon's autoscaling and branching handle the bursty, parallel workloads of thousands of training rollouts while keeping costs low.