school-ui
It's a ChatGPT-style assistant for my school — except the AI doesn't live in some company's cloud. It runs on one small machine sitting in the building, and nothing anyone types ever leaves the premises. A whole school's AI, on a box the size of a hardback book.
That single choice — keep it in the building — is what makes it usable by teenagers at all, and it's why the interesting engineering here is less about the AI and more about privacy: your conversations are locked so tightly that even the person running the server can't read them.
school-ui is built for Lessing-Gymnasium Karlsruhe's roughly 800 students and teachers, with no external AI provider behind it. It's currently in a controlled pilot; a wider rollout is gated on the teachers' conference and data-protection sign-off.
Privacy first
school-ui is used by minors. That's the first thing that shaped every technical decision.
When you sign up, the system generates a unique encryption key just for you. That key locks your conversations so that nobody else can read them — not other users, not teachers, not whoever runs the system. The key itself is sealed behind your password in a way that makes it practically impossible to recover without it. Even with full access to the database, all anyone would find is noise.
The key only exists in memory while you're logged in. When you log out, it's gone. Nothing readable ever touches the disk.
This isn't just a policy — it's enforced at the level of the data itself, where it can't be worked around.
The hardware
Everything runs on an NVIDIA DGX Spark — a machine roughly the size of a hardback book, weighing 1.2 kg. It has 128 GB of unified memory, which is enough to hold a 120-billion-parameter language model alongside everything else school-ui needs, without any slowdown. The entire school's AI fits on one desk and draws about as much power as a gaming laptop.
The model
school-ui runs an open-source 120-billion-parameter model, adapted to the school not by retraining but by everything around it: retrieval over curated school knowledge, role and policy layers, and prompts that know the curriculum, internal structure, and how the school operates. Students and teachers interact through a familiar chat interface, but the assistant behind it actually knows their context.
Memory
school-ui remembers things across conversations. Not in a vague way — it builds a real profile for each user over time. If you mention you prefer shorter explanations, or that you're working on a specific topic, school-ui notes it. A background process periodically reviews and organises these notes into a coherent picture that shapes every future conversation.
Beyond profiles, completed conversations are stored and indexed by meaning. When a new question relates to something discussed weeks ago, school-ui finds it and brings the relevant parts into the current context — without you needing to reference it yourself.
Teacher projects
Teachers can build structured projects for their classes. A project gives school-ui a specific role — a tutor for a particular chapter, a writing assistant for a specific assignment. Teachers attach the relevant material, set the scope, and optionally add prompts to guide students in.
Students join with a code. Inside, they get an assistant that knows the material and stays on topic. Teachers can see who's participating, but not what anyone said.
Streaming and resilience
Responses stream back word by word as the model generates them. Each fragment is encrypted before it passes through the system's internal buffer. If a student's connection drops mid-response — laptop closed, Wi-Fi cut out — the stream holds. When they reconnect, it resumes exactly where it stopped.
A separate process handles updates and restarts independently from the rest of the system, so changes can be pushed from a dashboard without taking anything down.
Where it stands
school-ui ran a controlled pilot through July 2026 and is now going through the slow part on purpose: an external security review, threat modeling with professionals, and the school's own governance — the teachers' conference and data-protection review decide when it scales. A system used by minors doesn't get to skip that, and I'd rather list what's still open than pretend it isn't.