整个课程和数据UI重新设计版本

kouyu_english/lib/core/generated_content.dart

@@ -1,6 +1,6 @@
 import 'dart:convert';
 
-import 'a0_core.dart';
+import 'courses/courses.dart';
 import 'models.dart';
 
 /// A bounded AI-authored variation of an existing review item. It never
@@ -120,6 +120,40 @@ bool matchesAdaptiveLessonAnswer(GeneratedLessonTask task, String answer) {
   return accepted || slots;
 }
 
+/// Explains in Chinese why [matchesAdaptiveLessonAnswer] rejects [answer],
+/// or returns null when it accepts it. Listening answers only get a count so
+/// the explanation does not replace listening again.
+String? adaptiveAnswerShortfall(GeneratedLessonTask task, String answer) {
+  if (matchesAdaptiveLessonAnswer(task, answer)) return null;
+  final actual = _normalizeAnswer(answer);
+  if (actual.isEmpty) return '请先输入或说出答案。';
+  final spec = task.localAnswerSpec;
+  final forbidden = spec.forbiddenPhrases
+      .where((phrase) => _containsPhrase(actual, phrase))
+      .toList();
+  if (forbidden.isNotEmpty) {
+    return '这里不能用：${forbidden.join('、')}。';
+  }
+  final missing = spec.requiredAnyPhrases
+      .where(
+        (alternatives) =>
+            !alternatives.any((phrase) => _containsPhrase(actual, phrase)),
+      )
+      .toList();
+  if (task.skill == 'listening') {
+    return '还缺 ${missing.isEmpty ? 1 : missing.length} 处关键信息。再听一次，或慢放后补全。';
+  }
+  if (missing.isEmpty || answerSpecIsReferenceOnly(spec, task.answer)) {
+    return '和参考表达还不一致，检查拼写和漏掉的词。';
+  }
+  return '还缺：${missing.map((group) => group.take(3).join(' / ')).join('；')}。';
+}
+
+bool answerSpecIsReferenceOnly(GeneratedAnswerSpec spec, String answer) =>
+    spec.requiredAnyPhrases.length == 1 &&
+    spec.requiredAnyPhrases.single.length == 1 &&
+    spec.requiredAnyPhrases.single.single == answer;
+
 String _normalizeAnswer(String value) => value
     .toLowerCase()
     .replaceAll('’', "'")
@@ -157,7 +191,7 @@ GeneratedReviewVariant? decodeGeneratedReviewVariant(
         expectedAnswer.trim().isEmpty ||
         expectedAnswer.length > 120 ||
         targetItemId != expectedTargetItemId ||
-        !a0CoreItems.containsKey(targetItemId)) {
+        !isCoreItem(targetItemId)) {
       return null;
     }
     return GeneratedReviewVariant(
@@ -231,7 +265,7 @@ GeneratedLesson? decodeGeneratedLesson(
         rawTasks is! List ||
         targets.length != 1 ||
         targets.single != expectedTargetItemId ||
-        !a0CoreItems.containsKey(expectedTargetItemId) ||
+        !isCoreItem(expectedTargetItemId) ||
         newItems.isNotEmpty ||
         preview.isNotEmpty ||
         chunks.isNotEmpty ||