German Tutor

A daily German lesson and three grading check-ins, in character, over WhatsApp.

A tutor that remembers yesterday beats a better tutor that does not.

I live in Zürich and my partner speaks only German at home. That is the real curriculum; this AI agent is the structure around it.

Every morning it sends a lesson. Three times a day it checks in, grades what I wrote back, and logs what I got wrong. It has a name and a personality, which sounds like a gimmick and turned out to matter, answering a person is a different act from completing an exercise.

How it is built

Progress lives in plain notes: vocabulary, weak spots, what has been covered. Each lesson reads those first, so the AI agent teaches into the gaps rather than marching through a syllabus. Mistakes made on Tuesday reappear on Friday.

It deliberately complements a commercial language app rather than replacing it, the app drills vocabulary, the AI agent handles the sentences I actually need to say at home.

What it got wrong

It sent lessons into a dead window. When another browser session was logged into the same messaging account, keystrokes went nowhere. The AI agent believed it had sent the lesson; nothing arrived. Every send now verifies the message is actually in the thread before reporting success.

It got the group name subtly wrong. A single misspelled character in the target chat name meant the AI agent was writing into a group that no longer existed, for longer than it should have taken anyone to notice.

The lesson

The language model was never the hard part. Delivery was. Roughly all of the engineering here went into getting the message in front of a human reliably, and almost none into what the message said.