diff --git a/skills/tts-voice/handler.ts b/skills/tts-voice/handler.ts
index 2a943ae..e34796d 100644
--- a/skills/tts-voice/handler.ts
+++ b/skills/tts-voice/handler.ts
@@ -8,13 +8,15 @@
  *   - curl CLI
  */
 
+import { randomUUID } from 'crypto';
 import { spawnSync } from 'child_process';
 import { readFileSync, existsSync, unlinkSync } from 'fs';
+import { join } from 'path';
+import { tmpdir } from 'os';
 
 const LUXTTS_BASE = 'http://localhost:7860';
 const REF_AUDIO = '/home/selig/LuxTTS/ref_speech.wav';
 const ENV_PATH = '/home/selig/LuxTTS/.env';
-const COOKIE_JAR = '/tmp/luxtts-skill-cookie';
 
 // Trigger keywords to strip from user message
 const TRIGGER_WORDS = [
@@ -38,6 +40,18 @@ interface TtsParams {
   tShift: number;
 }
 
+function createCookieJarPath(): string {
+  return join(tmpdir(), `luxtts-skill-cookie-${randomUUID()}.txt`);
+}
+
+function safeUnlink(path: string): void {
+  try {
+    if (existsSync(path)) unlinkSync(path);
+  } catch {
+    // ignore cleanup errors
+  }
+}
+
 /** Read credentials from .env */
 function loadCredentials(): { user: string; pass: string } {
   try {
@@ -51,10 +65,13 @@ function loadCredentials(): { user: string; pass: string } {
 }
 
 /** Ensure we have a valid session cookie */
-function ensureCookie(): boolean {
+function ensureCookie(cookieJar: string): boolean {
   const { user, pass } = loadCredentials();
   if (!pass) return false;
 
+  // always start fresh to avoid stale session side effects
+  safeUnlink(cookieJar);
+
   try {
     const result = spawnSync(
       'curl',
@@ -62,7 +79,7 @@ function ensureCookie(): boolean {
         '-s',
         '-o', '/dev/null',
         '-w', '%{http_code}',
-        '-c', COOKIE_JAR,
+        '-c', cookieJar,
         '-X', 'POST',
         '-d', `username=${user}&password=${pass}`,
         `${LUXTTS_BASE}/luxtts/login`,
@@ -71,7 +88,7 @@ function ensureCookie(): boolean {
     );
 
     const httpCode = (result.stdout || '').trim();
-    return result.status === 0 && httpCode === '200' && existsSync(COOKIE_JAR);
+    return result.status === 0 && httpCode === '200' && existsSync(cookieJar);
   } catch {
     return false;
   }
@@ -120,7 +137,7 @@ function parseMessage(message: string): { text: string; params: TtsParams } {
 }
 
 /** Call LuxTTS API to generate speech */
-function generateSpeech(text: string, params: TtsParams): string | null {
+function generateSpeech(text: string, params: TtsParams, cookieJar: string): string | null {
   const timestamp = Date.now();
   const outPath = `/tmp/tts_output_${timestamp}.wav`;
 
@@ -129,7 +146,7 @@ function generateSpeech(text: string, params: TtsParams): string | null {
       '-s',
       '-o', outPath,
       '-w', '%{http_code}',
-      '-b', COOKIE_JAR,
+      '-b', cookieJar,
       '-X', 'POST',
       `${LUXTTS_BASE}/luxtts/api/tts`,
       '-F', `ref_audio=@${REF_AUDIO}`,
@@ -151,10 +168,10 @@ function generateSpeech(text: string, params: TtsParams): string | null {
     }
 
     // Clean up failed output
-    if (existsSync(outPath)) unlinkSync(outPath);
+    safeUnlink(outPath);
     return null;
   } catch {
-    if (existsSync(outPath)) unlinkSync(outPath);
+    safeUnlink(outPath);
     return null;
   }
 }
@@ -180,34 +197,40 @@ export async function handler(ctx: any) {
     return { reply: '❌ LuxTTS 服務未啟動，請先執行：`systemctl --user start luxtts`' };
   }
 
-  // Ensure authentication
-  if (!ensureCookie()) {
-    return { reply: '❌ LuxTTS 認證失敗，請檢查 ~/LuxTTS/.env 的帳密設定' };
-  }
+  const cookieJar = createCookieJarPath();
 
-  // Build parameter description
-  const paramDesc: string[] = [];
-  if (params.speed !== 1.0) paramDesc.push(`語速 ${params.speed}x`);
-  if (params.numSteps !== 4) paramDesc.push(`步數 ${params.numSteps}`);
-  const paramStr = paramDesc.length ? `（${paramDesc.join('、')}）` : '';
+  try {
+    // Ensure authentication
+    if (!ensureCookie(cookieJar)) {
+      return { reply: '❌ LuxTTS 認證失敗，請檢查 ~/LuxTTS/.env 的帳密設定' };
+    }
 
-  // Generate
-  const wavPath = generateSpeech(text, params);
+    // Build parameter description
+    const paramDesc: string[] = [];
+    if (params.speed !== 1.0) paramDesc.push(`語速 ${params.speed}x`);
+    if (params.numSteps !== 4) paramDesc.push(`步數 ${params.numSteps}`);
+    const paramStr = paramDesc.length ? `（${paramDesc.join('、')}）` : '';
+
+    // Generate
+    const wavPath = generateSpeech(text, params, cookieJar);
+
+    if (!wavPath) {
+      return {
+        reply: '❌ 語音合成失敗，請稍後再試。',
+        metadata: { text, params, error: true },
+      };
+    }
 
-  if (!wavPath) {
     return {
-      reply: `❌ 語音合成失敗，請稍後再試。`,
-      metadata: { text, params, error: true },
+      reply: `🔊 語音合成完成${paramStr}\n\n📝 文字：${text}\n📂 檔案：\`${wavPath}\``,
+      metadata: {
+        text,
+        params,
+        output: wavPath,
+      },
+      files: [wavPath],
     };
+  } finally {
+    safeUnlink(cookieJar);
   }
-
-  return {
-    reply: `🔊 語音合成完成${paramStr}\n\n📝 文字：${text}\n📂 檔案：\`${wavPath}\``,
-    metadata: {
-      text,
-      params,
-      output: wavPath,
-    },
-    files: [wavPath],
-  };
 }