feat(05-02): exa-search research integration

backend/src/services/exaSearch.js

@@ -0,0 +1,75 @@
+const DEFAULT_EXA_API_URL = 'https://api.exa.ai/search';
+
+const buildSummary = (results) => {
+  if (!results || results.length === 0) {
+    return '';
+  }
+
+  const snippets = results
+    .map((result) => result.snippet || result.highlight)
+    .filter(Boolean);
+
+  if (snippets.length === 0) {
+    return results
+      .slice(0, 3)
+      .map((result) => result.title)
+      .filter(Boolean)
+      .join(' · ');
+  }
+
+  return snippets.slice(0, 3).join(' ');
+};
+
+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');
+  }
+
+  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) {
+    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
+};