fix: restore missing AI methods for word selection and chat

- Add selectSignificantWords method for AI-powered word selection
- Add generateContextualHint method for chat question responses
- Add getEnhancedFallback for graceful degradation
- These methods were missing after deployment simplification

src/aiService.js

@@ -19,6 +19,64 @@ class OpenRouterService {
     this.apiKey = key;
   }
 
+  async generateContextualHint(questionType, word, sentence, bookTitle, wordContext) {
+    if (!this.apiKey) {
+      return this.getEnhancedFallback(questionType, word, sentence, bookTitle);
+    }
+
+    try {
+      const prompts = {
+        part_of_speech: `What part of speech is the word "${word}" in this sentence: "${sentence}"? Provide a clear, direct answer.`,
+        sentence_role: `What grammatical role does "${word}" play in this sentence: "${sentence}"? Focus on its function.`,
+        word_category: `Is "${word}" an abstract or concrete noun? Explain briefly with an example.`,
+        synonym: `What's a good synonym for "${word}" that would fit in this sentence: "${sentence}"?`
+      };
+
+      const response = await fetch(this.apiUrl, {
+        method: 'POST',
+        headers: {
+          'Content-Type': 'application/json',
+          'Authorization': `Bearer ${this.apiKey}`,
+          'HTTP-Referer': window.location.origin,
+          'X-Title': 'Cloze Reader'
+        },
+        body: JSON.stringify({
+          model: this.model,
+          messages: [{
+            role: 'system',
+            content: 'You are a helpful reading tutor. Provide clear, educational answers that help students learn without giving away the answer directly.'
+          }, {
+            role: 'user',
+            content: prompts[questionType] || `Help me understand the word "${word}" in this context: "${sentence}"`
+          }],
+          max_tokens: 150,
+          temperature: 0.7
+        })
+      });
+
+      if (!response.ok) {
+        throw new Error(`API request failed: ${response.status}`);
+      }
+
+      const data = await response.json();
+      return data.choices[0].message.content.trim();
+    } catch (error) {
+      console.error('Error generating contextual hint:', error);
+      return this.getEnhancedFallback(questionType, word, sentence, bookTitle);
+    }
+  }
+
+  getEnhancedFallback(questionType, word, sentence, bookTitle) {
+    const fallbacks = {
+      part_of_speech: `Consider what "${word}" is doing in the sentence. Is it a person, place, thing (noun), an action (verb), or describing something (adjective)?`,
+      sentence_role: `Look at how "${word}" connects to other words around it. What is its job in making the sentence complete?`,
+      word_category: `Think about whether "${word}" is something you can touch or see (concrete) or an idea/feeling (abstract).`,
+      synonym: `What other word could replace "${word}" and keep the same meaning in this sentence?`
+    };
+    
+    return fallbacks[questionType] || `Think about what "${word}" means in this classic literature context.`;
+  }
+
   async getContextualHint(passage, wordToReplace, context) {
     if (!this.apiKey) {
       return 'API key required for contextual hints';
@@ -60,6 +118,64 @@ Provide a brief, educational hint that helps understand the word without giving
     }
   }
 
+  async selectSignificantWords(passage, count) {
+    if (!this.apiKey) {
+      throw new Error('API key required for word selection');
+    }
+
+    try {
+      const response = await fetch(this.apiUrl, {
+        method: 'POST',
+        headers: {
+          'Content-Type': 'application/json',
+          'Authorization': `Bearer ${this.apiKey}`,
+          'HTTP-Referer': window.location.origin,
+          'X-Title': 'Cloze Reader'
+        },
+        body: JSON.stringify({
+          model: this.model,
+          messages: [{
+            role: 'system',
+            content: 'You are an educational assistant that selects meaningful words from passages for cloze reading exercises. Select words that are important for comprehension and appropriate for the difficulty level.'
+          }, {
+            role: 'user',
+            content: `From this passage, select exactly ${count} meaningful words to create blanks for a cloze reading exercise. The words should be distributed throughout the passage and be important for understanding the text. Return ONLY the words as a JSON array, nothing else.
+
+Passage: "${passage}"`
+          }],
+          max_tokens: 100,
+          temperature: 0.3
+        })
+      });
+
+      if (!response.ok) {
+        throw new Error(`API request failed: ${response.status}`);
+      }
+
+      const data = await response.json();
+      const content = data.choices[0].message.content.trim();
+      
+      // Try to parse as JSON array
+      try {
+        const words = JSON.parse(content);
+        if (Array.isArray(words)) {
+          return words.slice(0, count);
+        }
+      } catch (e) {
+        // If not valid JSON, try to extract words from the response
+        const matches = content.match(/"([^"]+)"/g);
+        if (matches) {
+          return matches.map(m => m.replace(/"/g, '')).slice(0, count);
+        }
+      }
+      
+      throw new Error('Failed to parse AI response');
+    } catch (error) {
+      console.error('Error selecting words with AI:', error);
+      throw error;
+    }
+  }
+
   async getContextualization(title, author, passage) {
     if (!this.apiKey) {
       return `📚 Practice with classic literature from ${author}'s "${title}"`;