feat: 階段三 - AI 語意去重，失敗時降級保留所有問題

app/findings.js

@@ -61,3 +61,35 @@ export function mergeFindings(oldFindings, newFindings) {
 export function sortByLevel(findings) {
   return [...findings].sort((a, b) => LEVELS.indexOf(a.level) - LEVELS.indexOf(b.level));
 }
+
+/**
+ * 呼叫 LLM 進行語意去重，回傳去重後的 findings
+ * 失敗時降級回傳原始 findings
+ */
+export async function deduplicateWithAI(findings) {
+  if (findings.length === 0) return findings;
+
+  const systemPrompt = `你是一位程式碼審查問題去重專家。
+給你一份問題清單（JSON 陣列），請移除語意重複的問題（即使描述文字不同，但指的是同一個問題）。
+保留等級較高的版本，優先保留 critical > warning > info。
+只回傳去重後的 JSON 陣列，不要有其他文字。`;
+
+  const userContent = `以下是問題清單，請去除語意重複的項目：\n\n${JSON.stringify(findings, null, 2)}`;
+
+  try {
+    const result = await chatJSON(systemPrompt, userContent);
+    if (Array.isArray(result) && result.length > 0) {
+      console.log(`  AI 去重: ${findings.length} -> ${result.length} 筆`);
+      return result;
+    }
+    throw new Error('AI 回傳空陣列');
+  } catch (e) {
+    const status = e.response?.status;
+    if (status === 402 || status === 429) {
+      console.log(`  ⚠️  AI 去重失敗（${status} 額度/限流），降級：保留所有問題`);
+    } else {
+      console.log(`  ⚠️  AI 去重失敗（${e.message}），降級：保留所有問題`);
+    }
+    return findings;
+  }
+}

app/main.js

@@ -1,7 +1,7 @@
 import { GITEA_REPOSITORY, PR_NUMBER, PR_HEAD_BRANCH, PR_BASE_BRANCH, getLLMConfig } from './config.js';
 import { loadRoles, getRoleIntro } from './roles.js';
 import { getPRDiff, postComment } from './gitea.js';
-import { analyzeWithRole, loadOldFindings, mergeFindings, sortByLevel } from './findings.js';
+import { analyzeWithRole, loadOldFindings, mergeFindings, sortByLevel, deduplicateWithAI } from './findings.js';
 
 const WORKSPACE = process.env.GITHUB_WORKSPACE || '/workspace';
 
@@ -66,8 +66,13 @@ async function main() {
   console.log('\n🔀 Step3: Findings 合併');
   const oldFindings = loadOldFindings(WORKSPACE);
   const mergedFindings = mergeFindings(oldFindings, newFindings);
-  const sorted = sortByLevel(mergedFindings);
-  console.log(`  Step3 merged findings total=${sorted.length} (critical=${sorted.filter(f=>f.level==='critical').length} warning=${sorted.filter(f=>f.level==='warning').length} info=${sorted.filter(f=>f.level==='info').length})`);
+  console.log(`  Step3 merged findings total=${mergedFindings.length}`);
+
+  // Step3b: AI 語意去重
+  console.log('\n🤖 Step3b: AI 語意去重');
+  const deduped = await deduplicateWithAI(mergedFindings);
+  const sorted = sortByLevel(deduped);
+  console.log(`  Step3b dedup findings total=${sorted.length} (critical=${sorted.filter(f=>f.level==='critical').length} warning=${sorted.filter(f=>f.level==='warning').length} info=${sorted.filter(f=>f.level==='info').length})`);
 
   console.log('\n📝 Step4: Findings 寫入與 Comment 發布（待實作）');
   console.log('  [stub] 寫入 findings.json，發布 comment...');