feat(exercises): enhance gap exercise creation with contextual prompts and add migration for lesson 43

backend/migrations-active/20260826000000-repair-lesson-43-context-gap.cjs

@@ -0,0 +1,28 @@
+'use strict';
+
+const LESSON_TITLE = 'Kultur: Höflichkeit, Familie, Alltag';
+
+module.exports = {
+  async up(queryInterface) {
+    await queryInterface.sequelize.transaction(async (transaction) => {
+      // The old task asked for a soft refusal to an invitation, but expected
+      // the unrelated cultural keyword "respeto". Test the matching phrase.
+      await queryInterface.sequelize.query(`
+        UPDATE community.vocab_grammar_exercise AS exercise
+        SET question_data = '{"type":"gap_fill","text":"{gap}","gaps":1}'::jsonb,
+            answer_data = '{"type":"gap_fill","answers":["Dili lang sa karon."]}'::jsonb,
+            explanation = 'Das Kernmuster lautet: "Dili lang sa karon."'
+        FROM community.vocab_course_lesson AS lesson
+        WHERE exercise.lesson_id = lesson.id
+          AND (lesson.id = 40 OR (lesson.course_id = 1 AND lesson.lesson_number = 43))
+          AND exercise.title = :lessonTitle || ': Kernmuster ergänzen'
+          AND exercise.question_data->>'type' = 'gap_fill'
+          AND exercise.answer_data->'answers' @> '["respeto"]'::jsonb;
+      `, { replacements: { lessonTitle: LESSON_TITLE }, transaction });
+    });
+  },
+
+  async down() {
+    // Do not restore the semantically mismatched task.
+  }
+};

backend/scripts/create-bisaya-course-content.js

@@ -598,7 +598,24 @@ function buildGapExercise(lessonTitle, pattern) {
 }
 
 function buildContextGapExercise(lesson, didactics, pattern) {
-  const gapExercise = buildGapExercise(lesson.title, pattern);
+  const speakingPrompt = Array.isArray(didactics.speakingPrompts) ? didactics.speakingPrompts[0] : null;
+  const cue = normalizeText(speakingPrompt?.cue || '').toLowerCase();
+  // A contextual prompt must test a pattern that actually occurs in its
+  // scenario. Otherwise a cultural keyword such as "respeto" can be paired
+  // with an invitation-declining situation.
+  const scenarioPattern = didactics.corePatterns
+    .map((entry) => corePatternTarget(entry))
+    .find((candidate) => candidate && cue.includes(normalizeText(candidate).toLowerCase()));
+  const gapExercise = scenarioPattern
+    ? {
+        exerciseTypeId: 1,
+        title: `${lesson.title}: Kernmuster ergänzen`,
+        instruction: 'Fülle die Lücke mit dem passenden Bisaya-Ausdruck.',
+        questionData: { type: 'gap_fill', text: '{gap}', gaps: 1 },
+        answerData: { type: 'gap_fill', answers: [scenarioPattern] },
+        explanation: `Das Kernmuster lautet: "${scenarioPattern}".`
+      }
+    : buildGapExercise(lesson.title, pattern);
   if (!gapExercise) return null;
 
   return {