Most content systems hand whoever is editing a site enough power to break it, then rely on training and good intentions to stop them. SandraCMS works the other way round: the theme you write decides what a site can contain, and nothing — not the editing interface, not an API client, not an AI agent — can put anything else into it.
Not open for sign-up yet. We are still fine-tuning SandraCMS against real sites, so accounts are by invitation for the moment.
The sample theme and the API documentation are finished and public, though. Both are worth reading if you are working out whether this suits the way you build.