Lilian Weng, a cofounder of Thinking Machines Lab, steps down from the startup, citing health concerns related to the pace of the work. Multiple outlets report that she announces her departure and then returns to OpenAI within two days. Weng previously held a senior role at OpenAI, including serving as vice president of AI Safety Research, and she is now described as rejoining to lead an AI research team. The team’s work is linked to efforts around recursive self-improvement, in which AI systems are used to help develop or improve other AI models. Sources also note that Weng co-founded Thinking Machines Lab with Mira Murati, a former chief technology officer at OpenAI. Across reports, the main points are that Weng’s departure from Thinking Machines Lab is tied to her health, and that OpenAI brings her back quickly to focus on AI research related to self-improving capabilities.