The Symfony language server, and who wrote it

Symfony released an official language server this week. Buried past the feature list: Fabien writes that most of the code was written and reviewed by AI models, mainly Claude Fable 5 and GPT-5.6 Sol.

What stays with me isn’t the tooling, it’s what he says stayed with him: the architecture, the scope of each feature, and the final word on every change. Plenty of projects work this way right now, and almost none say so in the release notes, let alone name which part the human kept. He backs the claim with something checkable rather than just an assurance: an extensive test suite and performance benchmarks, not just a promise. AI-assisted code is already part of Symfony repositories, and that stopped being the interesting question a while ago; what matters is whether someone is responsible for it and treats that responsibility seriously. Who wrote a line is becoming a less useful question than who answers for it.