chat_template: robust to any client (Claude Code, OpenCode, Pi, etc.). Merges multi/mid-conversation system messages, drops no-user-query hard-fail, tolerates unknown content shapes, unknown roles, missing tool args, system+vision combos.

chat_template.jinja

@@ -5,43 +5,56 @@
         {{- content }}
     {%- elif content is iterable and content is not mapping %}
         {%- for item in content %}
-            {%- if 'image' in item or 'image_url' in item or item.type == 'image' %}
-                {%- if is_system_content %}
-                    {{- raise_exception('System message cannot contain images.') }}
-                {%- endif %}
-                {%- if do_vision_count %}
-                    {%- set image_count.value = image_count.value + 1 %}
-                {%- endif %}
-                {%- if add_vision_id %}
-                    {{- 'Picture ' ~ image_count.value ~ ': ' }}
-                {%- endif %}
-                {{- '<|vision_start|><|image_pad|><|vision_end|>' }}
-            {%- elif 'video' in item or item.type == 'video' %}
-                {%- if is_system_content %}
-                    {{- raise_exception('System message cannot contain videos.') }}
-                {%- endif %}
-                {%- if do_vision_count %}
-                    {%- set video_count.value = video_count.value + 1 %}
+            {%- if item is mapping and ('image' in item or 'image_url' in item or item.type == 'image') %}
+                {%- if not is_system_content %}
+                    {%- if do_vision_count %}
+                        {%- set image_count.value = image_count.value + 1 %}
+                    {%- endif %}
+                    {%- if add_vision_id %}
+                        {{- 'Picture ' ~ image_count.value ~ ': ' }}
+                    {%- endif %}
+                    {{- '<|vision_start|><|image_pad|><|vision_end|>' }}
                 {%- endif %}
-                {%- if add_vision_id %}
-                    {{- 'Video ' ~ video_count.value ~ ': ' }}
+            {%- elif item is mapping and ('video' in item or item.type == 'video') %}
+                {%- if not is_system_content %}
+                    {%- if do_vision_count %}
+                        {%- set video_count.value = video_count.value + 1 %}
+                    {%- endif %}
+                    {%- if add_vision_id %}
+                        {{- 'Video ' ~ video_count.value ~ ': ' }}
+                    {%- endif %}
+                    {{- '<|vision_start|><|video_pad|><|vision_end|>' }}
                 {%- endif %}
-                {{- '<|vision_start|><|video_pad|><|vision_end|>' }}
-            {%- elif 'text' in item %}
+            {%- elif item is mapping and 'text' in item %}
                 {{- item.text }}
-            {%- else %}
-                {{- raise_exception('Unexpected item type in content.') }}
+            {%- elif item is string %}
+                {{- item }}
             {%- endif %}
         {%- endfor %}
     {%- elif content is none or content is undefined %}
         {{- '' }}
     {%- else %}
-        {{- raise_exception('Unexpected content type.') }}
+        {{- content | string }}
     {%- endif %}
 {%- endmacro %}
 {%- if not messages %}
     {{- raise_exception('No messages provided.') }}
 {%- endif %}
+{#- Collect ALL system messages into a single leading system block. -#}
+{#- Tolerates: multiple system messages, system messages mid-conversation, no system message at all. -#}
+{%- set sys_ns = namespace(content='') %}
+{%- for message in messages %}
+    {%- if message.role == 'system' %}
+        {%- set part = render_content(message.content, false, true)|trim %}
+        {%- if part %}
+            {%- if sys_ns.content %}
+                {%- set sys_ns.content = sys_ns.content + '\n\n' + part %}
+            {%- else %}
+                {%- set sys_ns.content = part %}
+            {%- endif %}
+        {%- endif %}
+    {%- endif %}
+{%- endfor %}
 {%- if tools and tools is iterable and tools is not mapping %}
     {{- '<|im_start|>system\n' }}
     {{- "# Tools\n\nYou have access to the following functions:\n\n<tools>" }}
@@ -51,19 +64,18 @@
     {%- endfor %}
     {{- "\n</tools>" }}
     {{- '\n\nIf you choose to call a function ONLY reply in the following format with NO suffix:\n\n<tool_call>\n<function=example_function_name>\n<parameter=example_parameter_1>\nvalue_1\n</parameter>\n<parameter=example_parameter_2>\nThis is the value for the second parameter\nthat can span\nmultiple lines\n</parameter>\n</function>\n</tool_call>\n\n<IMPORTANT>\nReminder:\n- Function calls MUST follow the specified format: an inner <function=...></function> block must be nested within <tool_call></tool_call> XML tags\n- Required parameters MUST be specified\n- You may provide optional reasoning for your function call in natural language BEFORE the function call, but NOT after\n- If there is no function call available, answer the question like normal with your current knowledge and do not tell the user about function calls\n</IMPORTANT>' }}
-    {%- if messages[0].role == 'system' %}
-        {%- set content = render_content(messages[0].content, false, true)|trim %}
-        {%- if content %}
-            {{- '\n\n' + content }}
-        {%- endif %}
+    {%- if sys_ns.content %}
+        {{- '\n\n' + sys_ns.content }}
     {%- endif %}
     {{- '<|im_end|>\n' }}
 {%- else %}
-    {%- if messages[0].role == 'system' %}
-        {%- set content = render_content(messages[0].content, false, true)|trim %}
-        {{- '<|im_start|>system\n' + content + '<|im_end|>\n' }}
+    {%- if sys_ns.content %}
+        {{- '<|im_start|>system\n' + sys_ns.content + '<|im_end|>\n' }}
     {%- endif %}
 {%- endif %}
+{#- Find the index of the last real user query (not a tool response). -#}
+{#- If none exists, last_query_index stays at messages|length-1 so no assistant turn ever satisfies -#}
+{#- (loop.index0 > last_query_index), meaning all assistant <think> blocks are stripped — safe default. -#}
 {%- set ns = namespace(multi_step_tool=true, last_query_index=messages|length - 1) %}
 {%- for message in messages[::-1] %}
     {%- set index = (messages|length - 1) - loop.index0 %}
@@ -75,20 +87,16 @@
         {%- endif %}
     {%- endif %}
 {%- endfor %}
-{%- if ns.multi_step_tool %}
-    {{- raise_exception('No user query found in messages.') }}
-{%- endif %}
+{#- (Removed the "No user query found" hard-fail — some clients send system+assistant only.) -#}
 {%- for message in messages %}
     {%- set content = render_content(message.content, true)|trim %}
     {%- if message.role == "system" %}
-        {%- if not loop.first %}
-            {{- raise_exception('System message must be at the beginning.') }}
-        {%- endif %}
+        {#- already merged into the leading system block above -#}
     {%- elif message.role == "user" %}
         {{- '<|im_start|>' + message.role + '\n' + content + '<|im_end|>' + '\n' }}
     {%- elif message.role == "assistant" %}
         {%- set reasoning_content = '' %}
-        {%- if message.reasoning_content is string %}
+        {%- if message.reasoning_content is defined and message.reasoning_content is string %}
             {%- set reasoning_content = message.reasoning_content %}
         {%- else %}
             {%- if '</think>' in content %}
@@ -116,7 +124,7 @@
                 {%- else %}
                     {{- '\n<tool_call>\n<function=' + tool_call.name + '>\n' }}
                 {%- endif %}
-                {%- if tool_call.arguments is defined %}
+                {%- if tool_call.arguments is defined and tool_call.arguments %}
                     {%- for args_name, args_value in tool_call.arguments|items %}
                         {{- '<parameter=' + args_name + '>\n' }}
                         {%- set args_value = args_value | string if args_value is string else args_value | tojson | safe %}
@@ -131,6 +139,8 @@
     {%- elif message.role == "tool" %}
         {%- if loop.previtem and loop.previtem.role != "tool" %}
             {{- '<|im_start|>user' }}
+        {%- elif not loop.previtem %}
+            {{- '<|im_start|>user' }}
         {%- endif %}
         {{- '\n<tool_response>\n' }}
         {{- content }}
@@ -141,7 +151,10 @@
             {{- '<|im_end|>\n' }}
         {%- endif %}
     {%- else %}
-        {{- raise_exception('Unexpected message role.') }}
+        {#- Unknown role (e.g. "developer", "function", custom roles): render as user-style block so context is preserved instead of crashing. -#}
+        {%- if content %}
+            {{- '<|im_start|>user\n' + content + '<|im_end|>\n' }}
+        {%- endif %}
     {%- endif %}
 {%- endfor %}
 {%- if add_generation_prompt %}
@@ -151,4 +164,4 @@
     {%- else %}
         {{- '<think>\n' }}
     {%- endif %}
-{%- endif %}
+{%- endif %}