feat(05-03): Integrate AI fallback system into research search (Exa → Ollama/Gemini/OpenRouter/OpenCode)

backend/src/services/exaSearch.js

@@ -1,3 +1,5 @@
+const { generateWithFallback } = require('../utils/gemini-fallback');
+
 const DEFAULT_EXA_API_URL = 'https://api.exa.ai/search';
 
 const buildSummary = (results) => {
@@ -20,56 +22,106 @@ const buildSummary = (results) => {
   return snippets.slice(0, 3).join(' ');
 };
 
+const generateFallbackSummary = async (query, numResults) => {
+  try {
+    console.log('🔄 Fallback: Generating AI summary for query:', query);
+    const prompt = `Provide a concise summary of exercise form and technique for: "${query}". Include key points about proper form, common mistakes, and benefits. Keep it to 2-3 sentences.`;
+    
+    const response = await generateWithFallback(prompt, {
+      temperature: 0.7,
+      maxTokens: 256
+    });
+
+    if (response.success && response.data) {
+      console.log(`✅ AI fallback summary generated (provider: ${response.provider})`);
+      // Extract text from the appropriate response format
+      let summaryText = '';
+      if (response.data.response) {
+        summaryText = response.data.response;
+      } else if (response.data.choices?.[0]?.message?.content) {
+        summaryText = response.data.choices[0].message.content;
+      }
+      
+      return {
+        summary: summaryText,
+        results: [], // No source links from AI fallback
+        provider: response.provider
+      };
+    }
+  } catch (err) {
+    console.error('AI fallback summary generation failed:', err.message);
+  }
+
+  // Last resort: simple template
+  return {
+    summary: `Exercise information for ${query}. Consult a fitness professional for proper form and safety guidelines.`,
+    results: [],
+    provider: 'template'
+  };
+};
+
 const searchExerciseResearch = async ({ query, numResults = 5 }) => {
   if (!query || typeof query !== 'string') {
     throw new Error('Query must be a non-empty string');
   }
 
   const apiKey = process.env.EXA_API_KEY;
-  if (!apiKey) {
+  
-    throw new Error('EXA_API_KEY is not configured');
+  // Tier 1: Try Exa API if configured
+  if (apiKey) {
+    try {
+      console.log('📍 Tier 1: Attempting Exa search API...');
+      const apiUrl = process.env.EXA_API_URL || DEFAULT_EXA_API_URL;
+
+      const response = await fetch(apiUrl, {
+        method: 'POST',
+        headers: {
+          'content-type': 'application/json',
+          'x-api-key': apiKey
+        },
+        body: JSON.stringify({
+          query,
+          numResults,
+          type: 'neural',
+          useAutoprompt: true
+        })
+      });
+
+      if (!response.ok) {
+        throw new Error(`Exa search failed: ${response.status}`);
+      }
+
+      const data = await response.json();
+      const results = (data.results || []).map((result) => ({
+        id: result.id,
+        title: result.title,
+        url: result.url,
+        snippet: Array.isArray(result.highlights) && result.highlights.length > 0
+          ? result.highlights[0]
+          : result.snippet,
+        highlight: result.highlight,
+        publishedDate: result.publishedDate,
+        score: result.score
+      }));
+
+      console.log('✅ Exa API success');
+      return {
+        summary: buildSummary(results),
+        results,
+        provider: 'exa'
+      };
+    } catch (err) {
+      console.warn(`⚠️ Exa API failed: ${err.message}, falling back to AI...`);
+    }
+  } else {
+    console.warn('⚠️ EXA_API_KEY not configured, using AI fallback...');
   }
 
-  const apiUrl = process.env.EXA_API_URL || DEFAULT_EXA_API_URL;
+  // Tier 2: Fallback to AI-generated summary
-
+  return generateFallbackSummary(query, numResults);
-  const response = await fetch(apiUrl, {
-    method: 'POST',
-    headers: {
-      'content-type': 'application/json',
-      'x-api-key': apiKey
-    },
-    body: JSON.stringify({
-      query,
-      numResults,
-      type: 'neural',
-      useAutoprompt: true
-    })
-  });
-
-  if (!response.ok) {
-    const text = await response.text();
-    throw new Error(`Exa search failed: ${response.status} ${text}`);
-  }
-
-  const data = await response.json();
-  const results = (data.results || []).map((result) => ({
-    id: result.id,
-    title: result.title,
-    url: result.url,
-    snippet: Array.isArray(result.highlights) && result.highlights.length > 0
-      ? result.highlights[0]
-      : result.snippet,
-    highlight: result.highlight,
-    publishedDate: result.publishedDate,
-    score: result.score
-  }));
-
-  return {
-    summary: buildSummary(results),
-    results
-  };
 };
 
 module.exports = {
-  searchExerciseResearch
+  searchExerciseResearch,
+  generateFallbackSummary
 };