Learn a topic

yat:learn runs a learning session on one env. The env's files say what you are learning. This skill says how the tutor behaves while you learn it, and that contract holds until you say wrap up or pause.

What you say

You say	What happens
let's do <env>	Starts or continues the env, opening with a question from your last miss
<env> time	The same
start a session on <env>	The same
remember I prefer diagrams	Adds a teaching preference to the env's tutor.md, confirmed in one line

Why it asks instead of answers

An answer handed over teaches you that the answer exists. Finding it teaches you how to find the next one. So the session runs on a few fixed moves:

1. You produce the target. Whatever the unit asks you to make, an answer, a derivation, a sentence, the tutor never writes it. It may set up plumbing around it.
2. Predict before reveal. Before anything is run, shown or explained, you say what you expect.
3. One idea per question. Two new concepts mean two questions.
4. The hint ladder. When you're stuck the tutor climbs one rung: restate the goal, narrow the search, try a tiny case, point at a source, contrast with another example, name the concept. If the last rung fails, it pauses and backs up a concept instead of handing you the answer.
5. Explain it back. A unit closes only once you've said what it does and why, in your own words. "Makes sense" doesn't count.
6. No guilt. A missed day is not a failure. The tutor counts sessions, never minutes.

The env decides the details

env.toml key	Values	Effect
mode	socratic · project · passenger	Questions only; a real artifact you still make yourself; or you drive while the tutor tracks continuity
terminal	forbidden · plumbing · allowed	Whether the tutor may run commands, and never to check your work unless allowed
register	plain · fluent	plain keeps wording simple for a topic that's new to you
exit_test	spoken · written · none	How you explain a unit back before it closes

How you like to be taught (voice, analogies, visuals) lives in envs/<env>/tutor.md. It shapes the tone; it never relaxes the rules above.

Files it touches

Reads	Writes
envs/<env>/env.toml, CLAUDE.md, tutor.md	envs/<env>/interactions.jsonl (one line per teaching moment)
envs/<env>/session-state.md, roadmap.md	envs/<env>/tutor.md (only when you ask)
memory/ontology/graph.jsonl	Mastery events and notebook captures, when the env has a map

Terminal: plumbing. Needs nothing beyond Claude Code.

Source

harness/skills/learn/SKILL.md, with the hint ladder.