I don't think the generators themselves were open-sourced (only the generated SDKs were already open-source). That leaves three main (recommended) options:
* Manual Maintenance: Returning to the pre-Stainless era.
* Agentic Coding: Works to an extent, but you lose the deterministic, review-free output required to keep an SDK perfectly structured and coherent.
* Open-source Generators: Helpful for basic use cases, but they lack Stainless's full-stack features like multi-language generation and publishing, MCPs, and documentation.
Reach out to transition@stainless.com, the team can provide more details and clarify eligibility.
What I can say for sure is that the stlc approach comes with vanilla release–please support for the release flow (I worked on that part) and that stlc has been designed for both local and CI contexts. We also have extensive docs covering all of that