two questions per teaching unit: predict → teach → check (owner 2026-10-03)

The teaching cycle gains its motivation question. The teach quiz schema
now carries a REQUIRED type field — predict (posed before the teaching,
arrives open, the learner predicts the next step) or check (posed after,
arrives collapsed behind the reveal). The prober's quiz stays role-less.

- core: quizInputObject.type union + normalizeQuizType + the reveal law
  as pure quizNeedsReveal; QuestionData.questionType; note → thinking
  rename (legacy reads fold back); readingThinking channel on answers;
  compactAnswerForModel emits thinking / thinkingWhileReading
- tools: descriptions stripped to mechanics — QUIZ_OPTION_CRAFT and
  EXPLAIN_DOCTRINE deleted, doctrine moved to the prompt layer
  (reverses the 2026-09-27 placement, owner 2026-10-03); shared
  quizDescription/explainDescription builders differ only in deltas
- prompts: shared/20-question-tools.md rewritten (option craft,
  transcribed-speech leniency, the two thinking channels); new
  teacher/28-predictions.md (cycle, roles, skip rule, resolution law);
  20-teaching + 30-question-principles scoped to the new taxonomy
- UI: predictions render open with a Prediction eyebrow, verdict shows
  but the explanation tucks behind a toggle; the reading-thinking field
  mounts while a check waits (dictation claims it until reveal);
  answered card separates thinking vs thinking-while-reading blocks

tests/tool-parts.test.ts

@@ -29,6 +29,7 @@ const TEACHER_QUIZ = {
 	],
 	correctAnswer: "truth",
 	explanation: "Convention-T schematizes truth for the object language.",
+	type: "check", // teach-only role field — the display parse KEEPS it (the dock gates by it)
 	nodeId: "convention-t", // teacher-only field — the display parse must accept and strip it
 };
 
@@ -55,6 +56,7 @@ describe("parseQuizInput", () => {
 		assert.ok(parsed);
 		assert.equal(parsed.question, TEACHER_QUIZ.question);
 		assert.equal((parsed as Record<string, unknown>).nodeId, undefined, "unknown keys are stripped, not trusted");
+		assert.equal((parsed as { type?: unknown }).type, "check", "the role field survives the display parse (owner 2026-10-03)");
 	});
 
 	it("parses a boundary-valid PROBER quiz (no nodeId at all)", () => {