Add detailed logging for exercise caching issues

- Add comprehensive logging to saveExercise function
- Add detailed logging to tryGenerateAndCacheExercise function
- Improve error messages with more context
- Help diagnose French language caching failures

This will help identify why exercises are failing to save to cache
with undefined IDs for certain languages.

Author: rgilks

app/actions/exercise.ts

@@ -195,20 +195,37 @@ const tryGenerateAndCacheExercise = async (
   userId: number | null
 ): Promise<Result<{ content: ExerciseContent; id: number }, ActionError>> => {
   try {
+    console.log('[Exercise] Starting generation for:', {
+      passageLanguage: params.passageLanguage,
+      questionLanguage: params.questionLanguage,
+      level: params.level,
+      userId,
+    });
+
     const options: ExerciseGenerationOptions = { ...params, language: params.passageLanguage };
     const generatedExercise = await generateAndValidateExercise(options);
+
+    console.log('[Exercise] AI generation successful, attempting to save to cache...');
+
     const exerciseId = saveExerciseToCache(
       params.passageLanguage,
       params.questionLanguage,
       params.level,
       JSON.stringify(generatedExercise),
       userId
     );
+
     if (typeof exerciseId !== 'number') {
-      return failure({ error: 'Exercise generated but failed to save to cache (undefined ID).' });
+      console.error('[Exercise] Failed to save to cache - exerciseId is not a number:', exerciseId);
+      return failure({
+        error: `Exercise generated but failed to save to cache (undefined ID). Generated exercise: ${JSON.stringify(generatedExercise).substring(0, 100)}...`,
+      });
     }
+
+    console.log('[Exercise] Successfully saved exercise with ID:', exerciseId);
     return success({ content: generatedExercise, id: exerciseId });
   } catch (error) {
+    console.error('[Exercise] Error during generation:', error);
     return failure({
       error: `Error during AI generation/processing: ${error instanceof Error ? error.message : String(error)}`,
     });

app/repo/quizRepo.ts

@@ -109,16 +109,35 @@ export const saveExercise = (
   userId: number | null
 ): number | undefined => {
   try {
+    console.log('[QuizRepository] Attempting to save exercise:', {
+      passageLanguage,
+      questionLanguage,
+      level,
+      contentLength: contentJson.length,
+      userId,
+    });
+
     const result = db
       .prepare(
         'INSERT INTO quiz (language, level, content, question_language, user_id, created_at) VALUES (?, ?, ?, ?, ?, datetime("now")) RETURNING id'
       )
       .get(passageLanguage, level, contentJson, questionLanguage, userId) as
       | { id: number }
       | undefined;
-    return result?.id;
+
+    if (!result || typeof result.id !== 'number') {
+      console.error('[QuizRepository] Failed to get ID from database insert:', result);
+      return undefined;
+    }
+
+    console.log('[QuizRepository] Successfully saved exercise with ID:', result.id);
+    return result.id;
   } catch (error) {
     console.error('[QuizRepository] Error saving exercise:', error);
+    console.error('[QuizRepository] Error details:', {
+      message: error instanceof Error ? error.message : String(error),
+      stack: error instanceof Error ? error.stack : undefined,
+    });
     return undefined;
   }
 };