From e079cf16a212711663aa84cd4c2db064e8300922 Mon Sep 17 00:00:00 2001
From: Joaquin Hui <132194176+joaquinhuigomez@users.noreply.github.com>
Date: Sun, 12 Apr 2026 05:58:58 +0100
Subject: [PATCH] qwen3_5.jinja: handle list content on system messages (#3595)
 [skip ci]

* qwen3_5.jinja: handle list content on system messages

The system message branch used string concatenation on
messages[0].content, which breaks when the first system message uses
the OpenAI-style list-of-parts format that multimodal datasets require.
User and assistant branches already handle both string and list content,
but the system branch did not.

Check whether content is a string and fall back to iterating over parts
when it is a list, matching the pattern used for user messages.

Fixes #3590

* Address pr for other content types

---------

Co-authored-by: Joaquin Hui Gomez <joaquinhuigomez@users.noreply.github.com>
Co-authored-by: Wing Lian <wing@axolotl.ai>
---
 .../chat_templates/templates/qwen3_5.jinja    | 29 +++++++++++++++++--
 1 file changed, 27 insertions(+), 2 deletions(-)

diff --git a/src/axolotl/utils/chat_templates/templates/qwen3_5.jinja b/src/axolotl/utils/chat_templates/templates/qwen3_5.jinja
index 21f5733ed..c8d0e8da0 100644
--- a/src/axolotl/utils/chat_templates/templates/qwen3_5.jinja
+++ b/src/axolotl/utils/chat_templates/templates/qwen3_5.jinja
@@ -1,7 +1,19 @@
 {%- if tools %}
     {{- '<|im_start|>system\n' }}
     {%- if messages[0].role == 'system' %}
-        {{- messages[0].content + '\n\n' }}
+        {%- if messages[0].content is string %}
+            {{- messages[0].content + '\n\n' }}
+        {%- else %}
+            {%- for part in messages[0].content %}
+                {%- if part is mapping %}
+                    {%- set system_text = part.get('text') or part.get('content') or part.get('value') %}
+                    {%- if system_text %}{{- system_text }}{%- endif %}
+                {%- elif part is string %}
+                    {{- part }}
+                {%- endif %}
+            {%- endfor %}
+            {{- '\n\n' }}
+        {%- endif %}
     {%- endif %}
     {{- "# Tools\n\nYou may call one or more functions to assist with the user query.\n\nYou are provided with function signatures within <tools></tools> XML tags:\n<tools>" }}
     {%- for tool in tools %}
@@ -11,7 +23,20 @@
     {{- "\n</tools>\n\nFor each function call, return a json object with function name and arguments within <tool_call></tool_call> XML tags:\n<tool_call>\n{\"name\": <function-name>, \"arguments\": <args-json-object>}\n</tool_call><|im_end|>\n" }}
 {%- else %}
     {%- if messages[0].role == 'system' %}
-        {{- '<|im_start|>system\n' + messages[0].content + '<|im_end|>\n' }}
+        {%- if messages[0].content is string %}
+            {{- '<|im_start|>system\n' + messages[0].content + '<|im_end|>\n' }}
+        {%- else %}
+            {{- '<|im_start|>system\n' }}
+            {%- for part in messages[0].content %}
+                {%- if part is mapping %}
+                    {%- set system_text = part.get('text') or part.get('content') or part.get('value') %}
+                    {%- if system_text %}{{- system_text }}{%- endif %}
+                {%- elif part is string %}
+                    {{- part }}
+                {%- endif %}
+            {%- endfor %}
+            {{- '<|im_end|>\n' }}
+        {%- endif %}
     {%- endif %}
 {%- endif %}
 {%- set ns = namespace(multi_step_tool=true, last_query_index=messages|length - 1) %}