diff --git a/aidialog/dialog.py b/aidialog/dialog.py
index 7811fba..f809dba 100644
--- a/aidialog/dialog.py
+++ b/aidialog/dialog.py
@@ -178,7 +178,7 @@ def ai_res(self):
         if self.msg_type != sprompt: return ''
         if isinstance(self.output, str): return self.output  # Handle legacy/direct string
         if res := first(L(self.output).filter(lambda x: nested_idx(x, 'metadata', 'is_ai_res'))):
-            return nested_idx(res, 'data', 'text/markdown') or ''
+            return join_out(nested_idx(res, 'data', 'text/markdown')) or ''
         return ''
 
     def __deepcopy__(self, memo):
diff --git a/nbs/01_dialog.ipynb b/nbs/01_dialog.ipynb
index eea4e84..566f4b6 100644
--- a/nbs/01_dialog.ipynb
+++ b/nbs/01_dialog.ipynb
@@ -440,7 +440,7 @@
     "        if self.msg_type != sprompt: return ''\n",
     "        if isinstance(self.output, str): return self.output  # Handle legacy/direct string\n",
     "        if res := first(L(self.output).filter(lambda x: nested_idx(x, 'metadata', 'is_ai_res'))):\n",
-    "            return nested_idx(res, 'data', 'text/markdown') or ''\n",
+    "            return join_out(nested_idx(res, 'data', 'text/markdown')) or ''\n",
     "        return ''\n",
     "\n",
     "    def __deepcopy__(self, memo):\n",
@@ -488,7 +488,7 @@
    "id": "018a4289",
    "metadata": {},
    "source": [
-    "Prompt outputs normalize on the way in: a string assigned to a prompt message's `output`, at construction or any time later, wraps through `prompt_output`, so `ai_res` and history rendering always see the one list format."
+    "Prompt outputs normalize in both directions. A string assigned to `Message.output` wraps through `prompt_output`. An ipynb MIME value can be a string or a list of lines. `ai_res` joins either form into one string for history rendering."
    ]
   },
   {
@@ -502,7 +502,9 @@
     "test_eq(pm.ai_res, 'A reply')\n",
     "pm.output = 'Edited reply'\n",
     "test_eq(pm.output, prompt_output('Edited reply'))\n",
-    "test_eq(pm.ai_res, 'Edited reply')"
+    "test_eq(pm.ai_res, 'Edited reply')\n",
+    "pm_lines = Message('q', msg_type=sprompt, output=prompt_output(['Line 1\\n', 'Line 2']))\n",
+    "test_eq(pm_lines.ai_res, 'Line 1\\nLine 2')"
    ]
   },
   {