diff --git a/package.json b/package.json
index 2ef334d..3e4aebe 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "telegram-codex-bot",
-  "version": "0.1.4",
+  "version": "0.1.5",
   "description": "Telegram bot powered by the local Codex CLI — zero-dependency, pm2-managed, with a built-in PM2 web viewer",
   "license": "MIT",
   "type": "commonjs",
diff --git a/src/bot.js b/src/bot.js
index 9b5a676..9f0c7f5 100644
--- a/src/bot.js
+++ b/src/bot.js
@@ -224,13 +224,21 @@ function startBot(config) {
       const existing = sessions.get(chatId);
 
       let result;
+      let sessionResetNote = '';
       try {
         result = await runCodex({ config, prompt, threadId: existing?.threadId || null, images, onProgress });
       } catch (err) {
-        // 舊會話可能已被 codex 清掉，找不到就自動開新會話重試一次
-        if (existing && /session|thread|conversation/i.test(err.message) && /not.*found|找不到|no .*(session|thread)/i.test(err.message)) {
+        // 舊會話 resume 不了的情況，自動開新會話重試一次：
+        // 1) 會話已被 codex 清掉（not found）
+        // 2) bot 換了模型，codex 拒絕跨模型 resume（recorded with model X but resuming with Y）
+        const sessionGone = /session|thread|conversation/i.test(err.message) && /not.*found|找不到|no .*(session|thread)/i.test(err.message);
+        const modelMismatch = /recorded with model/i.test(err.message);
+        if (existing && (sessionGone || modelMismatch)) {
           sessions.clear(chatId);
           result = await runCodex({ config, prompt, threadId: null, images, onProgress });
+          sessionResetNote = modelMismatch
+            ? '🆕 模型設定已變更，舊會話無法沿用，已自動開新會話（先前的對話記憶未帶入）。\n\n'
+            : '🆕 舊會話已失效，已自動開新會話。\n\n';
         } else {
           throw err;
         }
@@ -239,7 +247,7 @@ function startBot(config) {
       if (result.threadId) sessions.set(chatId, result.threadId);
 
       const footer = buildFooter(config, result.usage, modelMeta, codexDefaults);
-      const html = t.mdToTgHtml((result.text || '（Codex 沒有回覆文字）') + footer);
+      const html = t.mdToTgHtml(sessionResetNote + (result.text || '（Codex 沒有回覆文字）') + footer);
       await t.editOrSplit(chatId, statusMsg.message_id, html, { html: true });
       await t.react(chatId, message.message_id, '👍');
     } catch (error) {