Update chat_template.jinja

chat_template.jinja

@@ -1,3 +1,162 @@
+{%- set template_version = "qwen3.8-safe-v2" %}
+{#- -------------------------------------------------------------------------
+    Whitespace contract: every tag opener in this file carries a leading minus,
+    so it strips the whitespace and newlines that precede it. All emitted text
+    comes from string literals, which makes the rendered prompt byte-exact and
+    free of incidental newlines. Comment tags need the minus just as much as
+    block tags do; a plain comment tag breaks the strip chain and leaks the
+    surrounding indentation into the prompt.
+    ------------------------------------------------------------------------- -#}
+{#- The message list has to exist before anything else can inspect it. -#}
+{%- if not messages %}
+    {{- raise_exception('No messages provided.') }}
+{%- endif %}
+{#- -------------------------------------------------------------------------
+    Configuration
+    ------------------------------------------------------------------------- -#}
+{%- set _requested_tool_format =
+    tool_call_format if tool_call_format is defined else 'auto'
+%}
+{%- if _requested_tool_format not in ('auto', 'xml', 'json') %}
+    {{- raise_exception(
+        'Unexpected tool_call_format ' ~ _requested_tool_format ~
+        '. Supported values are auto (default), xml, and json.'
+    ) }}
+{%- endif %}
+{%- set add_vision_id = add_vision_id if add_vision_id is defined else false %}
+{%- set enable_thinking = enable_thinking if enable_thinking is defined else true %}
+{%- set auto_disable_thinking_with_tools =
+    auto_disable_thinking_with_tools
+    if auto_disable_thinking_with_tools is defined
+    else false
+%}
+{%- if preserve_reasoning is defined
+       and preserve_reasoning is not none
+       and preserve_thinking is defined
+       and preserve_thinking is not none
+       and preserve_reasoning != preserve_thinking %}
+    {{- raise_exception(
+        'preserve_reasoning and preserve_thinking were both provided with conflicting values.'
+    ) }}
+{%- endif %}
+{%- if preserve_reasoning is defined and preserve_reasoning is not none %}
+    {%- set _preserve_thinking = preserve_reasoning %}
+{%- elif preserve_thinking is defined and preserve_thinking is not none %}
+    {%- set _preserve_thinking = preserve_thinking %}
+{%- else %}
+    {%- set _preserve_thinking = true %}
+{%- endif %}
+{%- set max_tool_arg_chars =
+    max_tool_arg_chars if max_tool_arg_chars is defined else 0
+%}
+{%- set max_tool_response_chars =
+    max_tool_response_chars if max_tool_response_chars is defined else 0
+%}
+{%- if max_tool_arg_chars is not number or max_tool_arg_chars < 0 %}
+    {{- raise_exception('max_tool_arg_chars must be a non-negative number.') }}
+{%- endif %}
+{%- if max_tool_response_chars is not number or max_tool_response_chars < 0 %}
+    {{- raise_exception('max_tool_response_chars must be a non-negative number.') }}
+{%- endif %}
+{%- if tools is defined and tools is not none and tools %}
+    {%- if tools is string or tools is mapping or tools is not iterable %}
+        {{- raise_exception('tools must be an iterable list of tool definitions.') }}
+    {%- endif %}
+    {%- set _has_tools = true %}
+{%- else %}
+    {%- set _has_tools = false %}
+{%- endif %}
+{#- -------------------------------------------------------------------------
+    Resolve the tool-call wire format.
+
+    OpenAI-compatible servers hand assistant tool calls back with
+    `function.arguments` as a JSON *string*, not a mapping. The XML parameter
+    form needs the individual key/value pairs, and a chat template cannot
+    decode a JSON string: the standard chat-template environment provides
+    `tojson` but no inverse, and no codepoint-to-character primitive, so a
+    hand-rolled scanner could not decode \uXXXX escapes correctly. Guessing
+    would silently corrupt tool arguments, which is worse than any error.
+
+    So when the caller does not pin a format, render the whole prompt in the
+    JSON tool-call form if any tool call in the history carries string
+    arguments. That is lossless, needs no decoding, and keeps the system-prompt
+    instructions and the rendered history in one consistent format. Histories
+    whose arguments are all mappings still render as XML, byte-identically to
+    tool_call_format='xml'.
+
+    A caller that explicitly pins 'xml' still gets a hard error for string
+    arguments, because that request cannot be honoured faithfully.
+    ------------------------------------------------------------------------- -#}
+{%- set format_scan = namespace(has_json_string_arguments=false) %}
+{%- for message in messages %}
+    {%- if message.role == 'assistant'
+           and message.tool_calls is defined
+           and message.tool_calls is not none
+           and message.tool_calls
+           and message.tool_calls is not string
+           and message.tool_calls is not mapping
+           and message.tool_calls is iterable %}
+        {%- for tool_call in message.tool_calls %}
+            {%- if tool_call.function is defined
+                   and tool_call.function is not none %}
+                {%- set _tc = tool_call.function %}
+            {%- else %}
+                {%- set _tc = tool_call %}
+            {%- endif %}
+            {%- if _tc.arguments is defined
+                   and _tc.arguments is not none
+                   and _tc.arguments is string
+                   and _tc.arguments | trim
+                   and _tc.arguments | trim != '{}' %}
+                {%- set format_scan.has_json_string_arguments = true %}
+            {%- endif %}
+        {%- endfor %}
+    {%- endif %}
+{%- endfor %}
+{%- if _requested_tool_format == 'auto' %}
+    {%- if format_scan.has_json_string_arguments %}
+        {%- set _tool_format = 'json' %}
+    {%- else %}
+        {%- set _tool_format = 'xml' %}
+    {%- endif %}
+{%- else %}
+    {%- set _tool_format = _requested_tool_format %}
+{%- endif %}
+{%- set _thinking_enabled = enable_thinking %}
+{%- if auto_disable_thinking_with_tools and _has_tools %}
+    {%- set _thinking_enabled = false %}
+{%- endif %}
+{#- Validate reasoning effort even when thinking is disabled. -#}
+{%- set _effort_raw =
+    reasoning_effort if reasoning_effort is defined else 'xhigh'
+%}
+{%- if _effort_raw == 'high' or _effort_raw == 'xhigh' %}
+    {%- set _reasoning_effort = 'xhigh' %}
+{%- elif _effort_raw == 'medium' %}
+    {%- set _reasoning_effort = 'medium' %}
+{%- elif _effort_raw == 'low' %}
+    {%- set _reasoning_effort = 'low' %}
+{%- else %}
+    {{- raise_exception(
+        'Unexpected reasoning effort ' ~ _effort_raw ~
+        '. Supported values are high/xhigh, medium, and low.'
+    ) }}
+{%- endif %}
+{%- set reasoning_instructions = '' %}
+{%- if _thinking_enabled %}
+    {%- if _reasoning_effort == 'xhigh' %}
+        {%- set reasoning_instructions =
+            'Reasoning effort is set to xhigh. Please think carefully through the task, validate key assumptions, consider plausible alternatives, and prioritize correctness, consistency, and clarity in the final answer.'
+        %}
+    {%- elif _reasoning_effort == 'low' %}
+        {%- set reasoning_instructions =
+            'Reasoning effort is set to low. Keep your thinking brief and focused, moving directly to the conclusion without unnecessary elaboration.'
+        %}
+    {%- endif %}
+{%- endif %}
+{#- -------------------------------------------------------------------------
+    Content rendering
+    ------------------------------------------------------------------------- -#}
 {%- set image_count = namespace(value=0) %}
 {%- set video_count = namespace(value=0) %}
 {%- macro render_content(content, do_vision_count, is_system_content=false) %}
@@ -5,9 +164,41 @@
         {{- 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 item is not mapping %}
+                {{- raise_exception(
+                    'Content-list items must be mappings with a supported text, image, or video type.'
+                ) }}
+            {%- endif %}
+            {%- set _item_type = item.type if 'type' in item else none %}
+            {%- if _item_type is not none
+                   and _item_type not in ('text', 'image', 'image_url', 'video') %}
+                {{- raise_exception(
+                    'Unexpected content item type ' ~ _item_type ~ '.'
+                ) }}
+            {%- endif %}
+            {%- set _is_image =
+                _item_type == 'image'
+                or _item_type == 'image_url'
+                or 'image' in item
+                or 'image_url' in item
+            %}
+            {%- set _is_video =
+                _item_type == 'video'
+                or 'video' in item
+            %}
+            {%- if _is_image and _is_video %}
+                {{- raise_exception(
+                    'A content item cannot contain both image and video data.'
+                ) }}
+            {%- elif _item_type == 'text' and (_is_image or _is_video) %}
+                {{- raise_exception(
+                    'A text content item cannot also contain image or video data.'
+                ) }}
+            {%- elif _is_image %}
                 {%- if is_system_content %}
-                    {{- raise_exception('System message cannot contain images.') }}
+                    {{- raise_exception(
+                        'System and developer messages cannot contain images.'
+                    ) }}
                 {%- endif %}
                 {%- if do_vision_count %}
                     {%- set image_count.value = image_count.value + 1 %}
@@ -16,9 +207,11 @@
                     {{- 'Picture ' ~ image_count.value ~ ': ' }}
                 {%- endif %}
                 {{- '<|vision_start|><|image_pad|><|vision_end|>' }}
-            {%- elif 'video' in item or item.type == 'video' %}
+            {%- elif _is_video %}
                 {%- if is_system_content %}
-                    {{- raise_exception('System message cannot contain videos.') }}
+                    {{- raise_exception(
+                        'System and developer messages cannot contain videos.'
+                    ) }}
                 {%- endif %}
                 {%- if do_vision_count %}
                     {%- set video_count.value = video_count.value + 1 %}
@@ -27,10 +220,17 @@
                     {{- 'Video ' ~ video_count.value ~ ': ' }}
                 {%- endif %}
                 {{- '<|vision_start|><|video_pad|><|vision_end|>' }}
-            {%- elif 'text' in item %}
+            {%- elif _item_type == 'text' or 'text' in item %}
+                {%- if 'text' not in item or item.text is not string %}
+                    {{- raise_exception(
+                        'Text content items must contain a string text field.'
+                    ) }}
+                {%- endif %}
                 {{- item.text }}
             {%- else %}
-                {{- raise_exception('Unexpected item type in content.') }}
+                {{- raise_exception(
+                    'Unexpected item in content list. Expected text, image, or video content.'
+                ) }}
             {%- endif %}
         {%- endfor %}
     {%- elif content is none or content is undefined %}
@@ -39,58 +239,96 @@
         {{- raise_exception('Unexpected content type.') }}
     {%- endif %}
 {%- endmacro %}
-{%- if not messages %}
-    {{- raise_exception('No messages provided.') }}
-{%- endif %}
-{%- set reasoning_instructions = '' %}
-{%- if enable_thinking is undefined or enable_thinking is true %}
-    {%- set resolved_reasoning_effort = reasoning_effort|default('xhigh') %}
-    {%- if resolved_reasoning_effort not in ('xhigh', 'medium', 'low') %}
-        {{- raise_exception('Unexpected reasoning effort ' ~ reasoning_effort ~ '. Supported types are xhigh (default), medium, and low.') }}
+{#- -------------------------------------------------------------------------
+    Validate and merge leading system/developer messages
+    ------------------------------------------------------------------------- -#}
+{%- set head = namespace(count=0, seen_non_system=false) %}
+{%- for message in messages %}
+    {%- set _is_system =
+        message.role == 'system' or message.role == 'developer'
+    %}
+    {%- if _is_system %}
+        {%- if head.seen_non_system %}
+            {{- raise_exception(
+                'System and developer messages must appear before all user, assistant, and tool messages.'
+            ) }}
+        {%- endif %}
+        {%- set head.count = head.count + 1 %}
+    {%- else %}
+        {%- set head.seen_non_system = true %}
     {%- endif %}
-    {%- if resolved_reasoning_effort == 'xhigh' %}
-        {%- set reasoning_instructions = 'Reasoning effort is set to xhigh. Please think carefully through the task, validate key assumptions, consider plausible alternatives, and prioritize correctness, consistency, and clarity in the final answer.' %}
-    {%- elif resolved_reasoning_effort == 'low' %}
-        {%- set reasoning_instructions = 'Reasoning effort is set to low. Keep your thinking brief and focused, moving directly to the conclusion without unnecessary elaboration.' %}
+{%- endfor %}
+{%- set system_state = namespace(content='') %}
+{%- for message in messages[:head.count] %}
+    {%- set _part =
+        render_content(message.content, false, true) | trim
+    %}
+    {%- if _part %}
+        {%- if system_state.content %}
+            {%- set system_state.content =
+                system_state.content ~ '\n\n' ~ _part
+            %}
+        {%- else %}
+            {%- set system_state.content = _part %}
+        {%- endif %}
     {%- endif %}
-{%- endif %}
-{%- if tools and tools is iterable and tools is not mapping %}
+{%- endfor %}
+{%- set _system_content = system_state.content %}
+{%- set _msgs = messages[head.count:] %}
+{#- -------------------------------------------------------------------------
+    System prompt and tool instructions
+    ------------------------------------------------------------------------- -#}
+{%- if _has_tools %}
     {{- '<|im_start|>system\n' }}
     {%- if reasoning_instructions %}
-        {{- reasoning_instructions + '\n\n' }}
+        {{- reasoning_instructions ~ '\n\n' }}
     {%- endif %}
-    {{- "# Tools\n\nYou have access to the following functions:\n\n<tools>" }}
+    {{- '# Tools\n\nYou have access to the following functions:\n\n<tools>' }}
     {%- for tool in tools %}
-        {{- "\n" }}
+        {{- '\n' }}
         {{- tool | tojson }}
     {%- 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 %}
+    {{- '\n</tools>' }}
+    {%- if _tool_format == 'json' %}
+        {{- '\n\nIf you choose to call a function ONLY reply in the following format with NO suffix:\n\n<tool_call>\n{"name": "example_function_name", "arguments": {"example_parameter_1": "value_1", "example_parameter_2": "This is the value for the second parameter"}}\n</tool_call>\n\n<IMPORTANT>\nReminder:\n- Function calls MUST follow the specified format: a single JSON object with "name" and "arguments" keys 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>' }}
+    {%- else %}
+        {{- '\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>' }}
+    {%- endif %}
+    {%- if _system_content %}
+        {{- '\n\n' ~ _system_content }}
     {%- endif %}
     {{- '<|im_end|>\n' }}
 {%- else %}
-    {%- if messages[0].role == 'system' %}
-        {%- set content = render_content(messages[0].content, false, true)|trim %}
-        {%- if content %}
-            {{- '<|im_start|>system\n' + (reasoning_instructions + '\n\n' if reasoning_instructions else '')  + content + '<|im_end|>\n' }}
-        {%- elif reasoning_instructions %}
-            {{- '<|im_start|>system\n' + reasoning_instructions + '<|im_end|>\n' }}
-        {%- endif %}
+    {%- if _system_content %}
+        {{- '<|im_start|>system\n'
+            ~ (reasoning_instructions ~ '\n\n' if reasoning_instructions else '')
+            ~ _system_content
+            ~ '<|im_end|>\n'
+        }}
     {%- elif reasoning_instructions %}
-        {{- '<|im_start|>system\n' + reasoning_instructions + '<|im_end|>\n' }}
+        {{- '<|im_start|>system\n'
+            ~ reasoning_instructions
+            ~ '<|im_end|>\n'
+        }}
     {%- endif %}
 {%- endif %}
-{%- 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 %}
-    {%- if ns.multi_step_tool and message.role == "user" %}
-        {%- set content = render_content(message.content, false)|trim %}
-        {%- if not(content.startswith('<tool_response>') and content.endswith('</tool_response>')) %}
+{#- -------------------------------------------------------------------------
+    Find the last real user query
+    ------------------------------------------------------------------------- -#}
+{%- set ns = namespace(
+    multi_step_tool=true,
+    last_query_index=(_msgs | length) - 1
+) %}
+{%- for message in _msgs[::-1] %}
+    {%- set index = (_msgs | length - 1) - loop.index0 %}
+    {%- if ns.multi_step_tool and message.role == 'user' %}
+        {%- set _rendered_user =
+            render_content(message.content, false) | trim
+        %}
+        {%- if not (
+            _rendered_user.startswith('<tool_response>')
+            and _rendered_user.endswith('</tool_response>')
+        ) %}
             {%- set ns.multi_step_tool = false %}
             {%- set ns.last_query_index = index %}
         {%- endif %}
@@ -99,70 +337,240 @@
 {%- if ns.multi_step_tool %}
     {{- raise_exception('No user query found in messages.') }}
 {%- endif %}
-{%- 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 %}
-    {%- elif message.role == "user" %}
-        {{- '<|im_start|>' + message.role + '\n' + content + '<|im_end|>' + '\n' }}
-    {%- elif message.role == "assistant" %}
+{#- -------------------------------------------------------------------------
+    Conversation rendering
+    ------------------------------------------------------------------------- -#}
+{%- set history_state = namespace(previous_role='') %}
+{%- for message in _msgs %}
+    {%- set content =
+        render_content(message.content, true) | trim
+    %}
+    {%- if message.role == 'user' %}
+        {{- '<|im_start|>user\n'
+            ~ content
+            ~ '<|im_end|>\n'
+        }}
+    {%- elif message.role == 'assistant' %}
         {%- set reasoning_content = '' %}
-        {%- if message.reasoning_content is string %}
-            {%- set reasoning_content = message.reasoning_content %}
+        {%- if message.reasoning_content is defined
+               and message.reasoning_content is not none %}
+            {%- if message.reasoning_content is string %}
+                {%- set reasoning_content = message.reasoning_content %}
+            {%- else %}
+                {%- set reasoning_content =
+                    message.reasoning_content | string
+                %}
+            {%- endif %}
+        {%- elif message.thinking is defined
+                 and message.thinking is not none %}
+            {%- if message.thinking is string %}
+                {%- set reasoning_content = message.thinking %}
+            {%- else %}
+                {%- set reasoning_content =
+                    message.thinking | string
+                %}
+            {%- endif %}
         {%- endif %}
-        {%- set reasoning_content = reasoning_content|trim %}
-        {%- if preserve_thinking is undefined or preserve_thinking is true or loop.index0 > ns.last_query_index %}
-            {{- '<|im_start|>' + message.role + '\n<think>\n' + reasoning_content + '\n</think>\n\n' + content }}
+        {%- set reasoning_content = reasoning_content | trim %}
+        {#- Preserve the original invariant: when thinking is preserved,
+            always reconstruct the thinking block, even when it is empty. -#}
+        {%- if _preserve_thinking
+               or loop.index0 > ns.last_query_index %}
+            {{- '<|im_start|>assistant\n<think>\n'
+                ~ reasoning_content
+                ~ '\n</think>\n\n'
+                ~ content
+            }}
         {%- else %}
-            {{- '<|im_start|>' + message.role + '\n' + content }}
+            {{- '<|im_start|>assistant\n' ~ content }}
         {%- endif %}
-        {%- if message.tool_calls and message.tool_calls is iterable and message.tool_calls is not mapping %}
+        {%- if message.tool_calls is defined
+               and message.tool_calls is not none
+               and message.tool_calls %}
+            {%- if message.tool_calls is string
+                   or message.tool_calls is mapping
+                   or message.tool_calls is not iterable %}
+                {{- raise_exception(
+                    'assistant.tool_calls must be an iterable list of tool calls.'
+                ) }}
+            {%- endif %}
             {%- for tool_call in message.tool_calls %}
-                {%- if tool_call.function is defined %}
-                    {%- set tool_call = tool_call.function %}
+                {%- if tool_call.function is defined
+                       and tool_call.function is not none %}
+                    {%- set tc = tool_call.function %}
+                {%- else %}
+                    {%- set tc = tool_call %}
                 {%- endif %}
-                {%- if loop.first %}
-                    {%- if content|trim %}
-                        {{- '\n\n<tool_call>\n<function=' + tool_call.name + '>\n' }}
+                {%- if tc.name is not defined
+                       or tc.name is none
+                       or tc.name is not string
+                       or not tc.name %}
+                    {{- raise_exception(
+                        'Every tool call must have a non-empty string name.'
+                    ) }}
+                {%- endif %}
+                {%- set tc_name = tc.name %}
+                {%- if _tool_format == 'json' %}
+                    {%- if loop.first %}
+                        {%- if content | trim %}
+                            {{- '\n\n<tool_call>\n' }}
+                        {%- else %}
+                            {{- '<tool_call>\n' }}
+                        {%- endif %}
                     {%- else %}
-                        {{- '<tool_call>\n<function=' + tool_call.name + '>\n' }}
+                        {{- '\n<tool_call>\n' }}
+                    {%- endif %}
+                    {%- set _json_arguments = '{}' %}
+                    {%- if tc.arguments is defined
+                           and tc.arguments is not none %}
+                        {%- if tc.arguments is mapping %}
+                            {%- set _json_arguments =
+                                tc.arguments | tojson
+                            %}
+                        {%- elif tc.arguments is string %}
+                            {%- set _raw_arguments =
+                                tc.arguments | trim
+                            %}
+                            {%- if _raw_arguments %}
+                                {%- if not (
+                                    _raw_arguments.startswith('{')
+                                    and _raw_arguments.endswith('}')
+                                ) %}
+                                    {{- raise_exception(
+                                        'JSON tool-call arguments must be a JSON object string.'
+                                    ) }}
+                                {%- endif %}
+                                {%- set _json_arguments =
+                                    _raw_arguments
+                                %}
+                            {%- endif %}
+                        {%- else %}
+                            {{- raise_exception(
+                                'JSON tool-call arguments must be a mapping or a JSON object string.'
+                            ) }}
+                        {%- endif %}
                     {%- endif %}
+                    {{- '{"name": ' }}
+                    {{- tc_name | tojson }}
+                    {{- ', "arguments": ' }}
+                    {{- _json_arguments }}
+                    {{- '}\n</tool_call>' }}
                 {%- else %}
-                    {{- '\n<tool_call>\n<function=' + tool_call.name + '>\n' }}
-                {%- endif %}
-                {%- 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 %}
-                        {{- args_value }}
-                        {{- '\n</parameter>\n' }}
-                    {%- endfor %}
+                    {%- if loop.first %}
+                        {%- if content | trim %}
+                            {{- '\n\n<tool_call>\n<function='
+                                ~ tc_name
+                                ~ '>\n'
+                            }}
+                        {%- else %}
+                            {{- '<tool_call>\n<function='
+                                ~ tc_name
+                                ~ '>\n'
+                            }}
+                        {%- endif %}
+                    {%- else %}
+                        {{- '\n<tool_call>\n<function='
+                            ~ tc_name
+                            ~ '>\n'
+                        }}
+                    {%- endif %}
+                    {%- if tc.arguments is defined
+                           and tc.arguments is not none %}
+                        {%- if tc.arguments is mapping %}
+                            {%- for args_name, args_value
+                                   in tc.arguments | items %}
+                                {%- set _argument_name =
+                                    args_name | string
+                                %}
+                                {{- '<parameter='
+                                    ~ _argument_name
+                                    ~ '>\n'
+                                }}
+                                {#- Preserve strings verbatim. Serialize every
+                                    other type as JSON so booleans and null stay
+                                    true/false/null instead of True/False/None. -#}
+                                {%- if args_value is string %}
+                                    {%- set _argument_value =
+                                        args_value
+                                    %}
+                                {%- else %}
+                                    {%- set _argument_value =
+                                        args_value | tojson
+                                    %}
+                                {%- endif %}
+                                {%- if max_tool_arg_chars > 0
+                                       and _argument_value | length
+                                           > max_tool_arg_chars %}
+                                    {{- _argument_value[:max_tool_arg_chars] }}
+                                    {{- '\n[TRUNCATED — original length '
+                                        ~ (_argument_value | length | string)
+                                        ~ ' chars]'
+                                    }}
+                                {%- else %}
+                                    {{- _argument_value }}
+                                {%- endif %}
+                                {{- '\n</parameter>\n' }}
+                            {%- endfor %}
+                        {%- elif tc.arguments is string %}
+                            {%- set _raw_arguments =
+                                tc.arguments | trim
+                            %}
+                            {%- if _raw_arguments
+                                   and _raw_arguments != '{}' %}
+                                {{- raise_exception(
+                                    'tool_call_format="xml" requires tool-call arguments to be mappings, but received a JSON string. Parse the JSON string into a mapping before applying the template, or leave tool_call_format unset so the template can select the JSON tool-call format automatically.'
+                                ) }}
+                            {%- endif %}
+                        {%- else %}
+                            {{- raise_exception(
+                                'XML tool-call arguments must be a mapping. Parse JSON-string arguments before applying the template.'
+                            ) }}
+                        {%- endif %}
+                    {%- endif %}
+                    {{- '</function>\n</tool_call>' }}
                 {%- endif %}
-                {{- '</function>\n</tool_call>' }}
             {%- endfor %}
         {%- endif %}
         {{- '<|im_end|>\n' }}
-    {%- elif message.role == "tool" %}
-        {%- if loop.previtem and loop.previtem.role != "tool" %}
+    {%- elif message.role == 'tool' %}
+        {%- if history_state.previous_role != 'tool' %}
             {{- '<|im_start|>user' }}
         {%- endif %}
+        {%- if max_tool_response_chars > 0
+               and content | length > max_tool_response_chars %}
+            {%- set content =
+                content[:max_tool_response_chars]
+                ~ '\n[TRUNCATED — original length '
+                ~ (content | length | string)
+                ~ ' chars]'
+            %}
+        {%- endif %}
         {{- '\n<tool_response>\n' }}
         {{- content }}
         {{- '\n</tool_response>' }}
-        {%- if not loop.last and loop.nextitem.role != "tool" %}
+        {%- if loop.last %}
             {{- '<|im_end|>\n' }}
-        {%- elif loop.last %}
+        {%- elif _msgs[loop.index0 + 1].role != 'tool' %}
             {{- '<|im_end|>\n' }}
         {%- endif %}
+    {%- elif message.role == 'system'
+             or message.role == 'developer' %}
+        {{- raise_exception(
+            'System and developer messages must appear only at the beginning of the conversation.'
+        ) }}
     {%- else %}
-        {{- raise_exception('Unexpected message role.') }}
+        {{- raise_exception(
+            'Unexpected message role ' ~ message.role ~ '.'
+        ) }}
     {%- endif %}
+    {%- set history_state.previous_role = message.role %}
 {%- endfor %}
+{#- -------------------------------------------------------------------------
+    Generation prompt
+    ------------------------------------------------------------------------- -#}
 {%- if add_generation_prompt %}
     {{- '<|im_start|>assistant\n' }}
-    {%- if enable_thinking is defined and enable_thinking is false %}
+    {%- if not _thinking_enabled %}
         {{- '<think>\n\n</think>\n\n' }}
     {%- else %}
         {{- '<think>\n' }}