diff --git a/src/test/llm.test.js b/src/test/llm.test.js
index efcf0bf..cba53ed 100644
--- a/src/test/llm.test.js
+++ b/src/test/llm.test.js
@@ -3,7 +3,7 @@ import assert from 'node:assert/strict';
 import { mkdtemp, writeFile, chmod, rm, readFile } from 'fs/promises';
 import { tmpdir } from 'os';
 import { join } from 'path';
-import { extractBalancedJSON, extractJSONText, extractMeaningfulError } from '../llm.js';
+import { extractBalancedJSON, extractJSONText, extractMeaningfulError, mapWithConcurrency } from '../llm.js';
 
 const ENV_KEYS = [
   'AI_ASSISTANT_CLI', 'MODEL', 'OPENCODE_MODEL', 'PATH', 'AI_ASSISTANT_TIMEOUT_MS', 'AI_ASSISTANT_MAX_BUFFER',
@@ -273,3 +273,42 @@ describe('extractMeaningfulError', () => {
     assert.equal(extractMeaningfulError(null), '');
   });
 });
+
+describe('mapWithConcurrency', () => {
+  it('回傳與輸入同索引對應的結果（保序）', async () => {
+    const out = await mapWithConcurrency([1, 2, 3, 4], 2, async (n) => n * 10);
+    assert.deepEqual(out, [10, 20, 30, 40]);
+  });
+
+  it('遵守併發上限（同時執行數不超過 limit）', async () => {
+    let active = 0, peak = 0;
+    const wait = () => new Promise(r => setTimeout(r, 5));
+    await mapWithConcurrency([1, 2, 3, 4, 5, 6], 2, async () => {
+      active += 1; peak = Math.max(peak, active);
+      await wait();
+      active -= 1;
+    });
+    assert.ok(peak <= 2, `peak=${peak} 應 <= 2`);
+  });
+
+  it('limit 大於項目數時仍全部執行', async () => {
+    const out = await mapWithConcurrency(['a', 'b'], 10, async (s) => s.toUpperCase());
+    assert.deepEqual(out, ['A', 'B']);
+  });
+
+  it('limit<=0 表示不限制（全部同時並行）', async () => {
+    let active = 0, peak = 0;
+    const wait = () => new Promise(r => setTimeout(r, 5));
+    await mapWithConcurrency([1, 2, 3, 4, 5], 0, async () => {
+      active += 1; peak = Math.max(peak, active);
+      await wait();
+      active -= 1;
+    });
+    assert.equal(peak, 5, `peak=${peak} 應等於項目數（不限制）`);
+  });
+
+  it('空輸入回傳空陣列', async () => {
+    assert.deepEqual(await mapWithConcurrency([], 3, async () => 1), []);
+    assert.deepEqual(await mapWithConcurrency(null, 3, async () => 1), []);
+  });
+});