chat_template.jinja

{#-
  qwen38_flexible.jinja
  =====================================================================
  Drop-in replacement chat template for Qwen/Qwen3.8-27B (and other
  Qwen3.8 models), forked from the upstream chat_template.jinja.

  Same wire format (<|im_start|>/<|im_end|>, <think> blocks, tool_call
  XML), but without the rigid conversation-shape enforcement.

  RELAXED vs upstream:
    R1  No 'No user query found in messages.' raise. Assistant-first,
        user-less, or tool-response-only transcripts render fine.
    R2  System messages are allowed ANYWHERE in the transcript, not
        just at index 0. Mid-conversation system notes render as their
        own <|im_start|>system block instead of raising
        'System message must be at the beginning.'
    R3  'developer' role accepted as an alias for 'system' (OpenAI
        Responses-API convention used by modern harnesses).
    R4  Unknown roles (narrator, char, example_user, ...) render
        verbatim as <|im_start|>{role} ... <|im_end|> instead of
        raising 'Unexpected message role.'.
    R5  continue_final_message support: when true and the last message
        is an assistant turn, that turn is left open (no <|im_end|>)
        for prefilling, and no generation prompt is appended.
    R6  No alternation assumptions anywhere: consecutive user turns,
        consecutive assistant turns, assistant-leading transcripts and
        trailing assistant turns all render as-is.

  KEPT from upstream (byte-compatible rendering):
    - render_content macro with vision counters
    - reasoning_effort (xhigh / medium / low) instruction injection
    - preserve_thinking (defaults TRUE on 3.8) + last_query_index walk
    - tool definitions block and <tool_call>/<tool_response> rendering
    - generation prompt with enable_thinking gate

  USAGE
    llama.cpp : llama-server -m qwen38-27b-*.gguf \
                  --chat-template-file qwen38_flexible.jinja
    vLLM      : vllm serve Qwen/Qwen3.8-27B \
                  --chat-template qwen38_flexible.jinja \
                  --tool-call-parser qwen3_coder --reasoning-parser qwen3
    SGLang    : python -m sglang.launch_server --model-path Qwen/Qwen3.8-27B \
                  --chat-template qwen38_flexible.jinja \
                  --tool-call-parser qwen3_coder --reasoning-parser qwen3

  Forked from Qwen/Qwen3.8-27B/chat_template.jinja (2026-08-13).
  License: Apache 2.0 (same as upstream).
-#}
{%- set image_count = namespace(value=0) %}
{%- set video_count = namespace(value=0) %}
{%- macro render_content(content, do_vision_count, is_system_content=false) %}
    {%- if content is string %}
        {{- 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 is defined and 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 %}
                {%- endif %}
                {%- if add_vision_id is defined and add_vision_id %}
                    {{- 'Video ' ~ video_count.value ~ ': ' }}
                {%- endif %}
                {{- '<|vision_start|><|video_pad|><|vision_end|>' }}
            {%- elif 'text' in item %}
                {{- item.text }}
            {%- else %}
                {{- raise_exception('Unexpected item type in content.') }}
            {%- endif %}
        {%- endfor %}
    {%- elif content is none or content is undefined %}
        {{- '' }}
    {%- else %}
        {{- raise_exception('Unexpected content type.') }}
    {%- endif %}
{%- endmacro %}
{%- if not messages %}
    {{- raise_exception('No messages provided.') }}
{%- endif %}
{#- reasoning_effort instruction injection (identical to upstream) -#}
{%- 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.') }}
    {%- 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.' %}
    {%- endif %}
{%- endif %}
{#- R3: 'developer' at index 0 is treated exactly like 'system' -#}
{%- set first_is_system = messages[0].role == 'system' or messages[0].role == 'developer' %}
{%- if tools and tools is iterable and tools is not mapping %}
    {{- '<|im_start|>system\n' }}
    {%- if reasoning_instructions %}
        {{- reasoning_instructions + '\n\n' }}
    {%- endif %}
    {{- "# Tools\n\nYou have access to the following functions:\n\n<tools>" }}
    {%- for tool in tools %}
        {{- "\n" }}
        {%- if tool.function is defined %}
            {{- tool.function | tojson }}
        {%- else %}
            {{- tool | tojson }}
        {%- endif %}
    {%- 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 first_is_system %}
        {%- set content = render_content(messages[0].content, false, true)|trim %}
        {%- if content %}
            {{- '\n\n' + content }}
        {%- endif %}
    {%- endif %}
    {{- '<|im_end|>\n' }}
{%- else %}
    {%- if first_is_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 %}
    {%- elif reasoning_instructions %}
        {{- '<|im_start|>system\n' + reasoning_instructions + '<|im_end|>\n' }}
    {%- endif %}
{%- endif %}
{#- last_query_index walk (identical to upstream logic) -#}
{%- 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>')) %}
            {%- set ns.multi_step_tool = false %}
            {%- set ns.last_query_index = index %}
        {%- endif %}
    {%- endif %}
{%- endfor %}
{#- R1: upstream raised 'No user query found in messages.' here when the
   transcript has no non-tool-response user turn (assistant-first, RP
   transcripts, pure continuations). We simply keep the default index:
   with preserve_thinking=true (3.8 default) the index is not consulted
   anyway, and with preserve_thinking=false it only affects which
   historical <think> blocks survive. -#}
{%- if ns.multi_step_tool %}
    {%- set ns.last_query_index = messages|length - 1 %}
{%- endif %}
{%- for message in messages %}
    {%- set content = render_content(message.content, true)|trim %}
    {%- if message.role == "system" or message.role == "developer" %}
        {#- R2/R3: index 0 was already merged into the header above. A
           system/developer note LATER in the transcript renders as its
           own block instead of raising. -#}
        {%- if not loop.first %}
            {{- '<|im_start|>system\n' + content + '<|im_end|>\n' }}
        {%- endif %}
    {%- 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 %}
            {%- set reasoning_content = message.reasoning_content %}
        {%- else %}
            {#- Rescue thinking embedded in content (harnesses that stuff
               <think> into the content string). Handles </thinking> and
               whitespace variants emitted by some quant runtimes. -#}
            {%- set think_end = '' %}
            {%- if '</think>' in content %}
                {%- set think_end = '</think>' %}
            {%- elif '</thinking>' in content %}
                {%- set think_end = '</thinking>' %}
            {%- elif '</ think>' in content %}
                {%- set think_end = '</ think>' %}
            {%- elif '</think >' in content %}
                {%- set think_end = '</think >' %}
            {%- endif %}
            {%- if think_end %}
                {%- set parts = content.split(think_end) %}
                {%- set reasoning_content = parts[0] %}
                {%- set content = parts[1:] | join(think_end) %}
                {%- if '<think>' in reasoning_content %}
                    {%- set reasoning_content = reasoning_content.split('<think>')[1:] | join('<think>') %}
                {%- endif %}
            {%- endif %}
        {%- endif %}
        {%- set reasoning_content = reasoning_content | trim %}
        {%- set content = 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 }}
        {%- else %}
            {{- '<|im_start|>' + message.role + '\n' + content }}
        {%- endif %}
        {%- if message.tool_calls and message.tool_calls is iterable and message.tool_calls is not mapping %}
            {%- if '<tool_call>' in content %}
                {%- set content = content.split('<tool_call>')[0] | trim %}
            {%- endif %}
            {%- for tool_call in message.tool_calls %}
                {%- if tool_call.function is defined %}
                    {%- set tool_call = tool_call.function %}
                {%- endif %}
                {%- if loop.first %}
                    {%- if content|trim %}
                        {{- '\n\n<tool_call>\n<function=' + tool_call.name + '>\n' }}
                    {%- else %}
                        {{- '<tool_call>\n<function=' + tool_call.name + '>\n' }}
                    {%- endif %}
                {%- else %}
                    {{- '\n<tool_call>\n<function=' + tool_call.name + '>\n' }}
                {%- endif %}
                {%- if tool_call.arguments is defined and tool_call.arguments != '' %}
                    {%- if tool_call.arguments is mapping %}
                        {%- 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 %}
                    {%- elif tool_call.arguments is string %}
                        {{- raise_exception("qwen38_flexible: tool_call.arguments must be a JSON object (mapping), got a string. Deserialize the JSON-encoded arguments once on ingest and store the resulting object.") }}
                    {%- endif %}
                {%- endif %}
                {{- '</function>\n</tool_call>' }}
            {%- endfor %}
        {%- endif %}
        {#- R5: leave the final assistant turn OPEN (no <|im_end|>) when
           prefilling via continue_final_message. -#}
        {%- if continue_final_message is defined and continue_final_message and loop.last %}
        {%- else %}
            {{- '<|im_end|>\n' }}
        {%- endif %}
    {%- elif message.role == "tool" %}
        {%- if loop.previtem and loop.previtem.role != "tool" %}
            {{- '<|im_start|>user' }}
        {%- endif %}
        {{- '\n<tool_response>\n' }}
        {{- content }}
        {{- '\n</tool_response>' }}
        {%- if not loop.last and loop.nextitem.role != "tool" %}
            {{- '<|im_end|>\n' }}
        {%- elif loop.last %}
            {{- '<|im_end|>\n' }}
        {%- endif %}
    {%- else %}
        {#- R4: unknown roles render verbatim instead of raising.
           Handy for narrators / multi-character / example transcripts. -#}
        {{- '<|im_start|>' + message.role + '\n' + content + '<|im_end|>' + '\n' }}
    {%- endif %}
{%- endfor %}
{%- if add_generation_prompt and not (continue_final_message is defined and continue_final_message) %}
    {{- '<|im_start|>assistant\n' }}
    {%- if enable_thinking is defined and enable_thinking is false %}
        {{- '<think>\n\n</think>\n\n' }}
    {%- else %}
        {{- '<think>\n' }}
    {%- endif %}
{%- endif %}