chore(engine): pin 0.37.0; the root entry owns the set description

docs/LESSON-FORMAT.md

@@ -291,17 +291,29 @@ sets:
     version: '1.0.0'
     lesson_count: 1
     domain: language
-    description: >-
-      …
 metadata:
   author: your-handle
   license: CC-BY-SA-4.0
   lessons:
     - 01-greetings.json
 ```
 
-Then add the same set block to the **root** `manifest.yaml` under `sets:`, and
-add a row to the README table (keeping the totals line in sync).
+Then add the same set block to the **root** `manifest.yaml` under `sets:`, plus
+the set's `description`, and add a row to the README table (keeping the totals
+line in sync).
+
+A set is described twice, so each field has one home:
+
+- The **root** entry carries the `description`. Write it there only; a reader
+  of the set manifest inherits it, so a second copy can only drift.
+- The **set manifest** carries the lesson list (`metadata.lessons`).
+- Every other field appears in both and must be **identical**: `title`,
+  `title_native`, `tags`, `visibility`, `version`, `lesson_count` and the
+  rest. `make lint` compares the two entries of every set
+  (`validateManifestPair`, `MANIFEST-ENTRY-MISMATCH`).
+- Leave the lesson count out of the `title` and `description` prose, or keep
+  it equal to `lesson_count`: a digit count that differs is flagged
+  (`W-LESSON-COUNT-CLAIM`).
 
 Run `python scripts/validate_content.py` until it prints
 `All N set(s) passed validation.`

schema/engine-version.txt

@@ -1 +1 @@
-0.36.0
+0.37.0

scripts/validate_with_engine.mjs

@@ -31,7 +31,7 @@
  * validated instead of refused - `make lint-warnings` used to shell out to the
  * bare CLI (no registry) and died on ext content (content-test#71).
  */
-import { validateLesson, validateLessonQuality, validateManifest } from "learn-content-engine";
+import { validateLesson, validateLessonQuality, validateManifest, validateManifestPair } from "learn-content-engine";
 import { readFileSync, readdirSync, statSync } from "node:fs";
 import { join, relative } from "node:path";
 import { parse as parseYaml } from "yaml";
@@ -283,6 +283,21 @@ function selfTest() {
     console.log("self-test OK: the source language reaches the card-back script lint");
   }
 
+  // Root and set manifest (learn-content-engine#246): a field both carry
+  // with different values is surfaced, as a warning or an error depending
+  // on the pinned engine's tier.
+  const setEntry = { id: "s1", title: "Set", target_language: "es", level: "A1", version: "1.0.0", lesson_count: 1 };
+  const pair = validateManifestPair(
+    { name: "Root", sets: [{ ...setEntry, description: "Root text" }] },
+    { name: "Set", sets: [{ ...setEntry, description: "Set text" }] },
+  );
+  if (![...pair.errors, ...pair.warnings].some((issue) => issue.id.endsWith("-MANIFEST-ENTRY-MISMATCH"))) {
+    failures++;
+    console.error("SELF-TEST FAIL: a root/set manifest mismatch must be surfaced (MANIFEST-ENTRY-MISMATCH)");
+  } else {
+    console.log("self-test OK: a root/set manifest mismatch is surfaced");
+  }
+
   if (failures) return 1;
   console.log(`\nSelf-test passed: the gate rejects all bad-lesson classes, applies the quality minimums, gates the extension tier, and surfaces author warnings.`);
   return 0;
@@ -325,8 +340,15 @@ function validateAll(repoRoot, { showWarnings = false } = {}) {
       if (showWarnings && res.warnings.length) warned.push({ file: rel, warnings: res.warnings });
     } else if (rel.endsWith("manifest.yaml")) {
       manifests += 1;
-      const res = validateManifest(parseYaml(readFileSync(file, "utf8")));
+      const setManifest = parseYaml(readFileSync(file, "utf8"));
+      const res = validateManifest(setManifest);
       if (!res.valid) report(rel, res.errors);
+      // The set is described twice, here and in the root manifest; the two
+      // must agree (learn-content-engine#246). The engine's tier decides:
+      // a warning in 0.37.x, an error from the release that raises it.
+      const pair = validateManifestPair(rootManifest, setManifest);
+      if (!pair.valid) report(rel, pair.errors);
+      if (showWarnings && pair.warnings.length) warned.push({ file: rel, warnings: pair.warnings });
       // Manifest warnings were collected for lessons but DROPPED here, so the
       // set-level ordering gate (learn-content-engine#110, W-SET-ORDER-*)
       // reached this runner and reported nothing. A connected gate that

sets/de/python-basics/manifest.yaml

@@ -33,10 +33,6 @@ sets:
     path: sets/de/python-basics
     version: '1.0.0'
     lesson_count: 15
-    description: >-
-      Fünfzehn Einführungslektionen Python, auf Deutsch erklärt,
-      vom ersten print() bis zu List Comprehensions, mit
-      lauffähigen Code-Beispielen und erwarteter Ausgabe.
     tags:
       - beginner
       - programming

sets/de/react-19/manifest.yaml

@@ -43,15 +43,6 @@ sets:
     path: sets/de/react-19
     version: '1.0.0'
     lesson_count: 8
-    description: >-
-      React 19 an lauffähigem Code: pro Lektion eine Komponente, acht
-      Übungen darauf. Deckt 19.0 (Actions, use, ref als Prop, Server
-      Components), 19.2 (gebündelte Suspense-Enthüllung, useEffectEvent,
-      Activity) und 19.3 (ViewTransition, Fragment Refs) ab. Übungstypen
-      mit Schwerpunkt auf Code lesen: reading-comprehension,
-      error-correction, parsons, dazu ordering, categorization,
-      multiple_choice, matching, cloze mit echtem Trägersatz und eine
-      benotete Abschlussprüfung.
     tags:
       - programming
       - react

sets/de/react-fortgeschritten/manifest.yaml

@@ -32,13 +32,6 @@ sets:
     path: sets/de/react-fortgeschritten
     version: '1.0.1'
     lesson_count: 8
-    description: >-
-      Teil 2 der React-Reihe (Fortgeschritten, B1): acht Lektionen mit
-      überwiegend Multiple-Choice, Single-Answer als cloze select-mode und
-      „Wähle alle zutreffenden" als cloze multiselect, plus matching und
-      kurze Lückentext-Items. Themen: useEffect, Datenfetching, useContext,
-      useRef, Performance, Listen/Keys, Formulare, Komposition/Patterns.
-      Distraktoren aus klassischen React-Irrtümern. React-18, Hooks-first.
     tags:
       - react
       - javascript

sets/de/react-grundlagen/manifest.yaml

@@ -27,13 +27,6 @@ sets:
     path: sets/de/react-grundlagen
     version: '1.0.1'
     lesson_count: 5
-    description: >-
-      React-Grundlagen auf Deutsch für Einsteiger: fünf Lektionen mit
-      insgesamt 31 Karten, Theorieschritten und überwiegend
-      Multiple-Choice-Übungen (picture_choice mit plausiblen
-      Distraktoren) plus wenigen Lückentext-Items (cloze) zu React als
-      Library, Komponenten, JSX, Props, State/useState, Events und
-      Grundprinzipien.
     tags:
       - react
       - javascript