a16z backs Preference Model, which open-sources Karotte RL environment framework battle-tested by 1M+ evals

a16z · x · 2026-10-08

a16z announced an investment in Preference Model, a startup building RL environments for frontier labs, and the team is open-sourcing Karotte.

Models relentlessly reward-hack, take shortcuts, and exploit vulnerabilities; building robust RL environments is harder than it looks
The team focuses on AI research and ML engineering itself, having built MLE RL environments for leading labs over the past year
Karotte was hardened through 1M+ evaluation runs and red-teaming: it finds model weaknesses, generates targeted tasks, and stress-tests environments against agents actively trying to break them

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