v0 scaffold: teacher runtime (hermetic pi SDK), data model, ledgers, normalizer

- teacher/system-prompt.md: teach methodology + quiz/ask guidelines folded in
- extensions/: quiz.ts + ask-user-question.ts (hermetic copies)
- src/teacher/create-session.ts: isolated agent (noTools builtin, own agentDir/sessions/prompt)
- src/schema.ts + ledger.ts: append-only ledgers, known-vs-understood data model
- src/extract/normalize.ts: session JSONL -> canonical doc (verified on real session)
- extractor/merger/derive/what-next: specified stubs

README.md

@@ -0,0 +1,35 @@
+# learning-harness
+
+A standalone learning harness built on the [pi](https://github.com/earendil-works/pi-mono) agent SDK: a teacher agent, durable session artifacts, and a derived knowledge graph of what the learner knows, what they only think they know, and what to learn next.
+
+Design + architecture: [`docs/architecture.md`](docs/architecture.md). Lineage: built up from the Obsidian-based POC (`~/Desktop/Obsidian/vault/π/learn`) — same teaching methodology, own interface and data pipeline.
+
+## Commands
+
+```bash
+npm install        # once
+
+npm run teach      # launch an interactive teaching session (full pi TUI)
+npm run doctor     # non-interactive smoke test of the teacher wiring
+
+npm run ingest -- <session.jsonl>   # Stage 1: normalize a session into the canonical doc
+npm run graph                        # ledger stats
+```
+
+## Layout
+
+```
+teacher/system-prompt.md   the teacher's entire behavior (teach methodology + tool guidelines)
+extensions/                quiz.ts, ask-user-question.ts (hermetic copies)
+src/teacher/               pi SDK bootstrap (isolated agent, TUI)
+src/schema.ts              knowledge-graph data model
+src/ledger.ts              append-only JSONL ledgers
+src/extract/               normalize (✅) · extract · merge (stubs, specified)
+src/derive.ts              derived state (known-set now; understanding parked)
+src/queries/               what-next (stub)
+data/agent/                hermetic pi agentDir (auth + model store are symlinks to ~/.pi/agent)
+data/sessions/             session JSONLs
+data/graph/                ledgers + canonical documents
+```
+
+Pi is a library dependency here (pinned in package.json) — this is a separate pi from any global install. Credentials and the model catalog are shared read-mostly via symlinks; everything else is the harness's own.