feat: erweitere Vokabeltrainer um Unterstützung für Checkpoint-Lektionen und verbessere Übungsauswahl

backend/services/vocabService.js

@@ -2900,12 +2900,45 @@ export default class VocabService {
     });
     
     const isWeeklyReview = plainLesson.lessonType === 'weekly_review';
+    const isCheckpoint = (String(plainLesson.didacticMode || '').toLowerCase() === 'checkpoint')
+      || (/checkpoint/i.test(String(plainLesson.title || '')) && plainLesson.weekNumber != null);
 
     // Lade Vokabeln aus vorherigen Lektionen (für Wiederholung UND für gemischten Vokabeltrainer)
-    if (plainLesson.lessonNumber > 1 && !isWeeklyReview) {
+    if (plainLesson.lessonNumber > 1 && !isWeeklyReview && !isCheckpoint) {
       plainLesson.previousLessonExercises = await this._getReviewVocabExercises(plainLesson.courseId, plainLesson.lessonNumber);
     }
-    if (isWeeklyReview) {
+
+    // Checkpoint-Lektionen: kleine Stichprobe aus den Wochen-Übungen (ca. 10-30%)
+    if (isCheckpoint) {
+      const weeklyLessons = await this._getReviewLessons(
+        plainLesson.courseId,
+        plainLesson.lessonNumber,
+        plainLesson.weekNumber
+      );
+      const weeklyExercises = await this._getReviewVocabExercises(
+        plainLesson.courseId,
+        plainLesson.lessonNumber,
+        plainLesson.weekNumber
+      );
+      plainLesson.reviewLessons = weeklyLessons;
+      plainLesson.previousLessonExercises = [];
+      plainLesson.weeklyReviewTrainingExercises = weeklyExercises;
+      plainLesson.reviewVocabExercises = this._selectCheckpointExamExercises(weeklyExercises, plainLesson.id);
+      plainLesson.weeklyReviewExamCount = plainLesson.reviewVocabExercises.length;
+      plainLesson.weeklyReviewTrainingCount = weeklyExercises.length;
+      plainLesson.corePatterns = weeklyLessons.flatMap((entry) => {
+        if (Array.isArray(entry.corePatterns)) return entry.corePatterns;
+        if (typeof entry.corePatterns === 'string') {
+          try {
+            const parsed = JSON.parse(entry.corePatterns);
+            return Array.isArray(parsed) ? parsed : [];
+          } catch (error) {
+            return [];
+          }
+        }
+        return [];
+      });
+    } else if (isWeeklyReview) {
       const weeklyLessons = await this._getReviewLessons(
         plainLesson.courseId,
         plainLesson.lessonNumber,
@@ -3210,6 +3243,17 @@ export default class VocabService {
     return this._seededShuffle(list.slice(), seed).slice(0, targetCount);
   }
 
+  _selectCheckpointExamExercises(exercises = [], lessonId) {
+    const list = Array.isArray(exercises) ? exercises : [];
+    if (list.length === 0) return [];
+
+    const seed = (Number(lessonId) * 100003) >>> 0;
+    // Checkpoints: smaller sample ~10-30%
+    const percentage = 10 + (seed % 21);
+    const targetCount = Math.max(1, Math.ceil((list.length * percentage) / 100));
+    return this._seededShuffle(list.slice(), seed).slice(0, targetCount);
+  }
+
   /**
    * Sammelt Grammatik‑Übungen aus vorherigen Lektionen derselben Woche
    */

frontend/src/views/social/VocabLessonView.vue

@@ -1390,11 +1390,12 @@ export default {
       }
       return core;
     },
-    /** Für Wiederholungslektionen: Übungen aus vorherigen Lektionen (Kapitelprüfung). Sonst: eigene Grammatik-Übungen. */
+    /** Für Wiederholungslektionen und Checkpoints: Übungen aus vorherigen Lektionen (Kapitelprüfung). Sonst: eigene Grammatik-Übungen. */
     effectiveExercises() {
       if (!this.lesson) return [];
-      const isReview = ['review', 'vocab_review', 'weekly_review'].includes(this.lesson.lessonType);
+      // Wenn die API bereits reviewVocabExercises liefert (z.B. für Wochenwiederholungen oder Checkpoints),
-      if (isReview && this.lesson.reviewVocabExercises && Array.isArray(this.lesson.reviewVocabExercises) && this.lesson.reviewVocabExercises.length > 0) {
+      // nutze diese explizit – sie enthalten die Kapitel-/Checkpoint-Übungen.
+      if (this.lesson.reviewVocabExercises && Array.isArray(this.lesson.reviewVocabExercises) && this.lesson.reviewVocabExercises.length > 0) {
         return this.lesson.reviewVocabExercises;
       }
       if (this.lesson.grammarExercises && Array.isArray(this.lesson.grammarExercises)) {