chore: take in the 16 Sep bundle — lib, curriculum v5, prompt, gate audit

The artifact was reworked after real incidents: a week of lost data, a
student taught out of order, and spelling diagnoses the model invented.
This takes the new export in verbatim; the port catches up in the
commits that follow.

Copied byte-identical from the bundle:
  lib/        lexicon.js and sync.js are new; gate.js gains enforcement,
              hangul.js letter-level marking, srs.js recall evidence,
              conjugation.js deconjugate(); blocks.js now takes the last
              block, closes gloss at "=", and parses recall, ::result and
              ::confirmed
  data/       curriculum.json v5 — six 다지기 phase reviews; the 371
              roadmap words are unchanged and no band moves
  prompt/     English-only rule, recall, LETTER-LEVEL CHECK, marking
  audit-gate.mjs, run-checks.sh, fixtures/  — the word gate measured
              against 54 real tutor messages

CI runs run-checks.sh in place of validate.mjs alone, and `npm run check`
gains the audit. Baselines: validate PASS 0/0; audit 7 of 41 and 2 of 13.

types/lib/ declares the new API, and test/lib/ pins it: letterCheck on
the prompt's own 짧다/빫다 case, deconjugation, the roadmap-first order
that keeps 마셔 out of Phase 1, sync's three gates, and recall evidence —
including the two ways lib's evidence is looser than PORT.md, pinned as
they are so the call site that tightens them is visibly needed.

TaskHost gains a plain recall renderer so the tree typechecks against the
wider Task union.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

app/src/ui/tutor/TaskHost.tsx

@@ -1,4 +1,4 @@
-/* The four exercise types, rendered as real interface.
+/* The five exercise types, rendered as real interface.
 
    State lives HERE, in the component, keyed by the turn it belongs to. The
    artifact rebuilt taskState inside its full-page re-render, so anything
@@ -14,6 +14,7 @@ import type {
   BuildTask,
   ChoiceTask,
   MatchTask,
+  RecallTask,
   Task,
   TranslateTask,
 } from "@lib/blocks.js";
@@ -35,6 +36,7 @@ function shuffle<T>(items: T[], seed: number): T[] {
 
 const LABEL: Record<Task["type"], string> = {
   translate: "type what each line means",
+  recall: "write it in 한글",
   match: "tap a Korean word, then its meaning",
   build: "tap or drag the words into order",
   choice: "one pick per line",
@@ -92,6 +94,53 @@ function Translate({ task, answers, setAnswers, disabled, onEnter }: {
   );
 }
 
+/* ── recall ──────────────────────────────────────────────────────── */
+
+/* English prompt; he writes the 한글. The keyboard wiring and the
+   letter-level check arrive with the answer mode — this renders the task
+   so it can be answered at all. */
+function Recall({ task, answers, setAnswers, disabled, onEnter }: {
+  task: RecallTask;
+  answers: string[];
+  setAnswers: (a: string[]) => void;
+  disabled: boolean;
+  onEnter: () => void;
+}) {
+  return (
+    <div className="ti">
+      {task.items.map((it, i) => (
+        <div className="ti-row recall" key={i}>
+          <span className="q">
+            {it.q}
+            {it.hint && <span className="rc-hint"> · {it.hint}</span>}
+          </span>
+          <input
+            type="text"
+            className="ko"
+            value={answers[i] ?? ""}
+            disabled={disabled}
+            placeholder="한국어로…"
+            autoComplete="off"
+            spellCheck={false}
+            aria-label={`Write ${it.q} in Korean`}
+            onChange={(e) => {
+              const next = [...answers];
+              next[i] = e.target.value;
+              setAnswers(next);
+            }}
+            onKeyDown={(e) => {
+              if (e.key === "Enter") {
+                e.preventDefault();
+                onEnter();
+              }
+            }}
+          />
+        </div>
+      ))}
+    </div>
+  );
+}
+
 /* ── match ───────────────────────────────────────────────────────── */
 
 interface Pair {
@@ -310,6 +359,7 @@ export function TaskHost({ task, turnId, lookups, onSubmit, onSkip, disabled = f
   const filled = (() => {
     switch (task.type) {
       case "translate":
+      case "recall":
         return { n: answers.filter((a) => a?.trim()).length, of: task.items.length };
       case "match":
         return { n: done.length, of: task.pairs.length };
@@ -326,6 +376,8 @@ export function TaskHost({ task, turnId, lookups, onSubmit, onSkip, disabled = f
       switch (task.type) {
         case "translate":
           return answerText(task, answers, lookups);
+        case "recall":
+          return answerText(task, answers, lookups);
         case "match":
           return answerText(task, { pairs: done }, lookups);
         case "build":
@@ -354,6 +406,15 @@ export function TaskHost({ task, turnId, lookups, onSubmit, onSkip, disabled = f
             onEnter={submit}
           />
         )}
+        {task.type === "recall" && (
+          <Recall
+            task={task}
+            answers={answers}
+            setAnswers={setAnswers}
+            disabled={disabled}
+            onEnter={submit}
+          />
+        )}
         {task.type === "match" && (
           <Match
             task={task}

app/src/ui/tutor/task.css

@@ -64,6 +64,21 @@
   min-width: 0;
 }
 
+/* recall: the prompt is English and the answer is 한글, so the weights swap */
+.ti-row.recall .q {
+  font-size: 16px;
+}
+
+.ti-row.recall input {
+  font-size: 19px;
+  font-weight: 500;
+}
+
+.rc-hint {
+  font-size: 12px;
+  color: var(--ink3);
+}
+
 /* ── match ───────────────────────────────────────────────────────── */
 
 .mt-cols {