diff --git a/.gitea/workflows/review.yaml b/.gitea/workflows/review.yaml
index b2ca93a..6fbcb0b 100644
--- a/.gitea/workflows/review.yaml
+++ b/.gitea/workflows/review.yaml
@@ -33,7 +33,7 @@ jobs:
     - name: AI Code Review
       uses: https://gitea.jsc.idv.tw/jiantw83/code-review@v${{ needs.version.outputs.version }}
       with:
-        GEMINI_API_KEY: ${{ secrets.GEMINI_API_KEY_1 }}
+        GEMINI_API_KEY: ${{ secrets.GEMINI_API_KEY }},${{ secrets.GEMINI_API_KEY_1 }},${{ secrets.GEMINI_API_KEY_2 }},${{ secrets.GEMINI_API_KEY_3 }},${{ secrets.GEMINI_API_KEY_4 }},${{ secrets.GEMINI_API_KEY_5 }},${{ secrets.GEMINI_API_KEY_6 }},${{ secrets.GEMINI_API_KEY_7 }},${{ secrets.GEMINI_API_KEY_8 }},${{ secrets.GEMINI_API_KEY_9 }}
         GEMINI_BASE_URL: https://generativelanguage.googleapis.com/v1beta
         GEMINI_MODEL: ${{ vars.GEMINI_MODEL }}
     permissions:
diff --git a/README.md b/README.md
index dd5d383..745001c 100644
--- a/README.md
+++ b/README.md
@@ -21,6 +21,7 @@
 3. Comment 加上些許 emoji 讓資訊有點活力
 4. 盡量將應用程式放在 ./app，修改 entrypoint.sh 與 Dockerfile 讓程式可以正常運行
 5. 將提示詞放到 ./app/prompts 內供程式讀取
+6. API Key 支援逗號分隔傳入多個，依序嘗試，失敗時自動換下一個，全部失敗則 exit 1
 
 # 使用說明
 
@@ -42,7 +43,7 @@ jobs:
     - name: AI Code Review
       uses: https://gitea.jsc.idv.tw/jiantw83/code-review@${{ vars.ACTION_CODE_REVIEW_VERSION }}
       with:
-        OPENAI_API_KEY: ${{ secrets.OPENAI_API_KEY }}
+        OPENAI_API_KEY: ${{ secrets.OPENAI_API_KEY }}  # 支援逗號分隔多個 Key
         OPENAI_BASE_URL: https://api.openai.com/v1
         OPENAI_MODEL: ${{ vars.OPENAI_MODEL }}
     permissions:
@@ -65,7 +66,7 @@ jobs:
     - name: AI Code Review
       uses: https://gitea.jsc.idv.tw/jiantw83/code-review@${{ vars.ACTION_CODE_REVIEW_VERSION }}
       with:
-        OPENAI_API_KEY: ${{ secrets.OPENROUTER_API_KEY }}  # OpenRouter 使用 OpenAI 相容介面，以 OPENAI_API_KEY 傳入
+        OPENAI_API_KEY: ${{ secrets.OPENROUTER_API_KEY }}  # OpenRouter 使用 OpenAI 相容介面，以 OPENAI_API_KEY 傳入，支援逗號分隔多個 Key
         OPENAI_BASE_URL: https://openrouter.ai/api/v1
         OPENAI_MODEL: ${{ vars.OPENROUTER_MODEL }}
     permissions:
@@ -88,7 +89,7 @@ jobs:
     - name: AI Code Review
       uses: https://gitea.jsc.idv.tw/jiantw83/code-review@${{ vars.ACTION_CODE_REVIEW_VERSION }}
       with:
-        CLAUDE_API_KEY: ${{ secrets.CLAUDE_API_KEY }}
+        CLAUDE_API_KEY: ${{ secrets.CLAUDE_API_KEY }}  # 支援逗號分隔多個 Key
         CLAUDE_BASE_URL: https://api.anthropic.com/v1
     permissions:
       contents: write
@@ -110,7 +111,7 @@ jobs:
     - name: AI Code Review
       uses: https://gitea.jsc.idv.tw/jiantw83/code-review@${{ vars.ACTION_CODE_REVIEW_VERSION }}
       with:
-        GEMINI_API_KEY: ${{ secrets.GEMINI_API_KEY }}
+        GEMINI_API_KEY: ${{ secrets.GEMINI_API_KEY }},${{ secrets.GEMINI_API_KEY_1 }},${{ secrets.GEMINI_API_KEY_2 }},${{ secrets.GEMINI_API_KEY_3 }},${{ secrets.GEMINI_API_KEY_4 }},${{ secrets.GEMINI_API_KEY_5 }},${{ secrets.GEMINI_API_KEY_6 }},${{ secrets.GEMINI_API_KEY_7 }},${{ secrets.GEMINI_API_KEY_8 }},${{ secrets.GEMINI_API_KEY_9 }}
         GEMINI_BASE_URL: https://generativelanguage.googleapis.com/v1beta
         GEMINI_MODEL: ${{ vars.GEMINI_MODEL }}
     permissions:
@@ -133,7 +134,7 @@ jobs:
     - name: AI Code Review
       uses: https://gitea.jsc.idv.tw/jiantw83/code-review@${{ vars.ACTION_CODE_REVIEW_VERSION }}
       with:
-        AMAZONQ_API_KEY: ${{ secrets.AMAZONQ_API_KEY }}
+        AMAZONQ_API_KEY: ${{ secrets.AMAZONQ_API_KEY }}  # 支援逗號分隔多個 Key
         AMAZONQ_BASE_URL: https://q.api.aws
     permissions:
       contents: write
diff --git a/TODO.md b/TODO.md
index 540a5c0..c605eac 100644
--- a/TODO.md
+++ b/TODO.md
@@ -35,6 +35,11 @@
 - 驗收：log 中能看到「critical 問題存在，workflow 結束（exit 1）」等明確訊息，且 workflow 狀態為失敗。
 - 完成
 
+## 階段八：API Key 輪替
+- 目標：所有平台的 API Key 支援逗號分隔傳入多個，依序嘗試，單一 Key 失敗時自動換下一個，全部失敗則 exit 1。
+- 驗收：log 中能看到「key[N/M] 失敗」等訊息，換 key 後繼續執行；傳入單一 Key 時行為與原本相同；全部 Key 失敗時 log「所有 API Key 均失敗，終止流程」且 workflow 狀態為失敗。
+- 完成
+
 ---
 
 所有階段驗收通過。
diff --git a/app/config.js b/app/config.js
index 3dc350e..c8212e3 100644
--- a/app/config.js
+++ b/app/config.js
@@ -8,16 +8,22 @@ export const PR_BASE_BRANCH = process.env.PR_BASE_BRANCH || '';
 export const FINDINGS_PATH = '.gitea/ai-review/findings.json';
 export const EXCLUSIONS_PATH = '.gitea/ai-review/exclusions.json';
 
+/** 將逗號分隔的 API key 字串拆成陣列 */
+function splitKeys(value) {
+  if (!value) return [];
+  return value.split(',').map(k => k.trim()).filter(Boolean);
+}
+
 export function getLLMConfig() {
   const checks = [
-    ['openai',   process.env.OPENAI_API_KEY,   process.env.OPENAI_BASE_URL || 'https://api.openai.com/v1',   process.env.OPENAI_MODEL || 'gpt-4o-mini'],
-    ['claude',   process.env.CLAUDE_API_KEY,   process.env.CLAUDE_BASE_URL || 'https://api.anthropic.com/v1', process.env.CLAUDE_MODEL || 'claude-3-haiku-20240307'],
-    ['gemini',   process.env.GEMINI_API_KEY,   process.env.GEMINI_BASE_URL || 'https://generativelanguage.googleapis.com/v1beta', process.env.GEMINI_MODEL || 'gemini-2.5-flash'],
-    ['ollama',   'ollama',                      process.env.OLLAMA_BASE_URL,  process.env.OLLAMA_MODEL],
-    ['amazonq',  process.env.AMAZONQ_API_KEY,  process.env.AMAZONQ_BASE_URL  || 'https://q.api.aws',              process.env.AMAZONQ_MODEL  || 'amazon-q'],
+    ['openai',   splitKeys(process.env.OPENAI_API_KEY),   process.env.OPENAI_BASE_URL || 'https://api.openai.com/v1',   process.env.OPENAI_MODEL || 'gpt-4o-mini'],
+    ['claude',   splitKeys(process.env.CLAUDE_API_KEY),   process.env.CLAUDE_BASE_URL || 'https://api.anthropic.com/v1', process.env.CLAUDE_MODEL || 'claude-3-haiku-20240307'],
+    ['gemini',   splitKeys(process.env.GEMINI_API_KEY),   process.env.GEMINI_BASE_URL || 'https://generativelanguage.googleapis.com/v1beta', process.env.GEMINI_MODEL || 'gemini-2.5-flash'],
+    ['ollama',   ['ollama'],                               process.env.OLLAMA_BASE_URL,  process.env.OLLAMA_MODEL],
+    ['amazonq',  splitKeys(process.env.AMAZONQ_API_KEY),  process.env.AMAZONQ_BASE_URL  || 'https://q.api.aws',              process.env.AMAZONQ_MODEL  || 'amazon-q'],
   ];
-  for (const [provider, key, baseURL, model] of checks) {
-    if (key && baseURL) return { provider, apiKey: key, baseURL, model };
+  for (const [provider, apiKeys, baseURL, model] of checks) {
+    if (apiKeys.length > 0 && baseURL) return { provider, apiKeys, baseURL, model };
   }
-  return { provider: null, apiKey: null, baseURL: null, model: null };
+  return { provider: null, apiKeys: [], baseURL: null, model: null };
 }
diff --git a/app/config.test.js b/app/config.test.js
index b757cec..03cf9ac 100644
--- a/app/config.test.js
+++ b/app/config.test.js
@@ -26,14 +26,14 @@ describe('getLLMConfig', () => {
   it('returns null provider when no env vars set', () => {
     const cfg = getLLMConfig();
     assert.equal(cfg.provider, null);
-    assert.equal(cfg.apiKey, null);
+    assert.deepEqual(cfg.apiKeys, []);
   });
 
   it('detects openai with defaults', () => {
     process.env.OPENAI_API_KEY = 'sk-test';
     const cfg = getLLMConfig();
     assert.equal(cfg.provider, 'openai');
-    assert.equal(cfg.apiKey, 'sk-test');
+    assert.deepEqual(cfg.apiKeys, ['sk-test']);
     assert.equal(cfg.baseURL, 'https://api.openai.com/v1');
     assert.equal(cfg.model, 'gpt-4o-mini');
   });
@@ -48,7 +48,14 @@ describe('getLLMConfig', () => {
     assert.equal(cfg.model, 'gpt-4o');
   });
 
-  it('detects gemini with defaults', () => {
+  it('detects gemini with comma-separated keys, picks one', () => {
+    process.env.GEMINI_API_KEY = 'key1,key2,key3';
+    const cfg = getLLMConfig();
+    assert.equal(cfg.provider, 'gemini');
+    assert.deepEqual(cfg.apiKeys, ['key1', 'key2', 'key3']);
+  });
+
+  it('detects gemini with single key (no comma)', () => {
     process.env.GEMINI_API_KEY = 'gemini-key';
     const cfg = getLLMConfig();
     assert.equal(cfg.provider, 'gemini');
diff --git a/app/llm.js b/app/llm.js
index db7217b..dddce5f 100644
--- a/app/llm.js
+++ b/app/llm.js
@@ -5,23 +5,31 @@ import { getLLMConfig } from './config.js';
 const httpsAgent = new https.Agent({ rejectUnauthorized: false });
 
 export async function chat(systemPrompt, userContent) {
-  const { provider, apiKey, baseURL, model } = getLLMConfig();
+  const { provider, apiKeys, baseURL, model } = getLLMConfig();
   if (!provider) throw new Error('未設定任何 LLM API Key');
 
   console.log(`  [LLM] provider=${provider} model=${model}`);
 
-  const headers = {
-    'Content-Type': 'application/json',
-    'Authorization': `Bearer ${apiKey}`,
-  };
+  const headers = { 'Content-Type': 'application/json' };
   if (provider === 'claude') headers['anthropic-version'] = '2023-06-01';
 
-  const resp = await axios.post(
-    `${baseURL.replace(/\/$/, '')}/chat/completions`,
-    { model, messages: [{ role: 'system', content: systemPrompt }, { role: 'user', content: userContent }], temperature: 0.2 },
-    { headers, timeout: 120000, httpsAgent }
-  );
-  return resp.data.choices[0].message.content;
+  let lastError;
+  for (let i = 0; i < apiKeys.length; i++) {
+    headers['Authorization'] = `Bearer ${apiKeys[i]}`;
+    try {
+      const resp = await axios.post(
+        `${baseURL.replace(/\/$/, '')}/chat/completions`,
+        { model, messages: [{ role: 'system', content: systemPrompt }, { role: 'user', content: userContent }], temperature: 0.2 },
+        { headers, timeout: 120000, httpsAgent }
+      );
+      return resp.data.choices[0].message.content;
+    } catch (e) {
+      lastError = e;
+      console.log(`  [LLM] key[${i + 1}/${apiKeys.length}] 失敗: ${e.message}`);
+    }
+  }
+  console.error('  [LLM] 所有 API Key 均失敗，終止流程');
+  process.exit(1);
 }
 
 export async function chatJSON(systemPrompt, userContent) {