It was the BEAM process/actor model that fit much better for managing agents, and then there was the out-of-the-box live UI with Phoenix/LiveView that was really appealing. I had started the project in Typescript/Node (because that's my company's primary stack choice), but it hit a plateau in reliably managing multiple independent long-lived agent processes (not really what Node is designed for). I could have used an even more boring tech like Go with more robust process management, but Elixir and Phoenix also came with a lot out of the box. It's no surprise that OpenAI's reference project for agent orchestration (https://github.com/openai/symphony) is also written in Elixir.