diff --git a/app/config.js b/app/config.js
index 4e37a2a..8de6c1f 100644
--- a/app/config.js
+++ b/app/config.js
@@ -59,13 +59,18 @@ function assertHttpUrl(name, value) {
 const MAX_REPO_NAME_LENGTH = 100;
 const REPO_SEGMENT_PATTERN = /^[A-Za-z0-9._-]+$/;
 
-// 驗證 repository 為 owner/repo 格式（拒絕 . 與 .. 路徑穿越段、空段、過長或含非法字元的段）
+// 單一 repository 區段是否合法：長度在範圍內、僅含允許字元，且非 . 或 .. 路徑穿越段
+function isValidRepoSegment(part) {
+    return part.length > 0
+        && part.length <= MAX_REPO_NAME_LENGTH
+        && REPO_SEGMENT_PATTERN.test(part)
+        && part !== '.' && part !== '..';
+}
+
+// 驗證 repository 為 owner/repo 格式（恰兩段，且每段皆為合法區段）
 function assertRepository(name, value) {
     const parts = value.split('/');
-    const isRepoFormatValid = parts.length === 2
-        && parts.every((part) => part.length > 0 && part.length <= MAX_REPO_NAME_LENGTH
-            && REPO_SEGMENT_PATTERN.test(part)
-            && part !== '.' && part !== '..');
+    const isRepoFormatValid = parts.length === 2 && parts.every(isValidRepoSegment);
     if (!isRepoFormatValid) {
         throw new Error(`${name} 格式錯誤，必須為 owner/repo`);
     }
diff --git a/app/releases.js b/app/releases.js
index 51982d3..0077843 100644
--- a/app/releases.js
+++ b/app/releases.js
@@ -66,8 +66,10 @@ async function fetchReleases(baseUrl, options = {}) {
         try {
             pageJson = JSON.parse(text);
         } catch {
-            // 以字元（而非 UTF-16 碼元）截斷回傳內容片段，避免拆分多位元組字元造成亂碼
-            const contentSnippet = Array.from(text).slice(0, API_ERROR_SNIPPET_LENGTH).join('');
+            // 先以 UTF-16 長度粗略上限截斷（避免將可能極大的回應整個陣列化），
+            // 再以字元（而非 UTF-16 碼元）精準截斷，避免拆分多位元組字元造成亂碼
+            const boundedText = text.slice(0, API_ERROR_SNIPPET_LENGTH * 2);
+            const contentSnippet = Array.from(boundedText).slice(0, API_ERROR_SNIPPET_LENGTH).join('');
             throw new Error(`release API 回傳資料無法解析 (page=${page})，回應內容片段：「${contentSnippet}」`);
         }