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

src/cli.ts

@@ -0,0 +1,78 @@
+#!/usr/bin/env node
+/**
+ * learning-harness CLI
+ *
+ *   teach [message]   launch an interactive teaching session (full pi TUI)
+ *   doctor            non-interactive smoke test of the teacher wiring
+ *   ingest <file>     normalize a session JSONL and print the canonical document
+ *                     (Stage 1 only — extractor/merger not yet implemented)
+ *   graph             print graph/ledger stats
+ *   what-next         (not yet implemented)
+ */
+
+import * as fs from "node:fs";
+import { doctor, runTeachingSession } from "./teacher/create-session.ts";
+import { normalizeSession } from "./extract/normalize.ts";
+import { ledgers } from "./ledger.ts";
+import { deriveAll } from "./derive.ts";
+import { PATHS } from "../config.ts";
+
+async function main() {
+	const [command, ...rest] = process.argv.slice(2);
+
+	switch (command) {
+		case "teach": {
+			await runTeachingSession(rest.join(" ") || undefined);
+			break;
+		}
+		case "doctor": {
+			await doctor();
+			break;
+		}
+		case "ingest": {
+			const file = rest[0];
+			if (!file) {
+				console.error("Usage: ingest <session.jsonl>");
+				process.exit(1);
+			}
+			const doc = normalizeSession(file);
+			ledgers.appendSession(doc.session);
+			console.log(`Session: ${doc.session.id}`);
+			console.log(`Topic:   ${doc.session.topic}`);
+			console.log(`Entries: ${doc.entries.length}`);
+			const quizzes = doc.entries.filter((e) => e.kind === "quiz");
+			console.log(`Quizzes: ${quizzes.length}`);
+			// Full canonical document for inspection / later pipeline stages.
+			fs.mkdirSync(PATHS.graph, { recursive: true });
+			const out = `${PATHS.graph}/canonical-${doc.session.id.slice(0, 8)}.json`;
+			fs.writeFileSync(out, JSON.stringify(doc, null, "\t"), "utf-8");
+			console.log(`Canonical document written: ${out}`);
+			break;
+		}
+		case "graph": {
+			const nodes = ledgers.nodes();
+			const edges = ledgers.edges();
+			const events = ledgers.events();
+			const sessions = ledgers.sessions();
+			const derived = deriveAll();
+			console.log(`Sessions: ${sessions.length}`);
+			console.log(`Nodes:    ${nodes.length} (known: ${derived.filter((d) => d.known).length})`);
+			console.log(`Edges:    ${edges.length}`);
+			console.log(`Events:   ${events.length}`);
+			break;
+		}
+		case "what-next": {
+			console.error("Not implemented yet — needs extractor + merger first.");
+			process.exit(1);
+		}
+		default: {
+			console.log("Commands: teach [message] | doctor | ingest <file> | graph | what-next");
+			process.exit(command ? 1 : 0);
+		}
+	}
+}
+
+main().catch((err) => {
+	console.error(err);
+	process.exit(1);
+});