{%- set ns = namespace(multi_step_tool=true, last_query_index=messages|length - 1) -%}
{%- set emit = namespace(started=false) -%}

{# ---------- Build base system message (always emitted) ---------- #}
{%- set base_system = 'You are rnj-1, a foundation model trained by Essential AI.\n' -%}

{# ---------- Optional tools preface as a synthetic system message ---------- #}
{%- if tools %}
  {%- set sys_preamble -%}
# Tools

You may call one or more functions to assist with the user query.

You are provided with function signatures within <tools></tools> XML tags:
<tools>
{%- for tool in tools %}
{{ "\n" ~ (tool | tojson) }}
{% endfor %}
</tools>

For each function call, return a json object with function name and arguments within <tool_call></tool_call> XML tags:
<tool_call>
{"name": <function-name>, "arguments": <args-json-object>}
</tool_call>
  {%- endset -%}

  {# If the first user-provided message is system, include it above the tools preface #}
  {%- set combined_system = (messages and messages[0].role == 'system')
      and (messages[0].content is string) -%}
  {%- set sys_content = (combined_system and (messages[0].content ~ "\n\n" ~ sys_preamble)) or sys_preamble -%}

  {%- set content = '<|start_header_id|>system<|end_header_id|>\n' ~ base_system ~ '\n' ~ sys_content ~ '<|eot_id|>' -%}
  {%- if not emit.started -%}{%- set content = bos_token ~ content -%}{%- set emit.started = true -%}{%- endif -%}
  {{- content -}}
{%- else %}
  {# No tools: always emit base_system, and include user's system message if present #}
  {%- set user_system_content = '' -%}
  {%- if messages and messages[0].role == 'system' and (messages[0].content is string) -%}
    {%- set user_system_content = '\n' ~ messages[0].content -%}
  {%- endif -%}
  {%- set content = '<|start_header_id|>system<|end_header_id|>\n' ~ base_system ~ user_system_content ~ '<|eot_id|>' -%}
  {%- if not emit.started -%}{%- set content = bos_token ~ content -%}{%- set emit.started = true -%}{%- endif -%}
  {{- content -}}
{%- endif -%}

{# ---------- Locate last user query for multi-step tool behavior ---------- #}
{%- for message in messages[::-1] %}
  {%- set index = (messages|length - 1) - loop.index0 -%}
  {%- if ns.multi_step_tool
        and message.role == "user"
        and message.content is string
        and not (message.content.startswith('<tool_response>') and message.content.endswith('</tool_response>')) -%}
    {%- set ns.multi_step_tool = false -%}
    {%- set ns.last_query_index = index -%}
  {%- endif -%}
{%- endfor -%}

{# ---------- Walk all messages and emit in Llama-3 format ---------- #}
{%- for message in messages %}
  {# normalize content #}
  {%- if message.content is string -%}
    {%- set content = message.content -%}
  {%- else -%}
    {%- set content = '' -%}
  {%- endif -%}

  {# --- user/system (non-initial system already handled above) --- #}
  {%- if (message.role == "user") or (message.role == "system" and not loop.first) -%}
    {%- set block = '<|start_header_id|>' ~ message.role ~ '<|end_header_id|>\n' ~ content ~ '<|eot_id|>' -%}
    {%- if not emit.started -%}{%- set block = bos_token ~ block -%}{%- set emit.started = true -%}{%- endif -%}
    {{- block -}}

  {# --- assistant --- #}
  {%- elif message.role == "assistant" -%}
  
    {%- set body = content -%}
    {%- set header = '<|start_header_id|>assistant<|end_header_id|>\n' -%}
    {%- if not emit.started -%}{{ bos_token }}{%- set emit.started = true -%}{%- endif -%}
    {{- header -}}
    {% generation %}
    {{- body -}}
    {%- if message.tool_calls -%}
      {%- for tool_call in message.tool_calls -%}
        {%- if tool_call.function -%}{%- set tc = tool_call.function -%}{%- else -%}{%- set tc = tool_call -%}{%- endif -%}
        {%- set args_json = (tc.arguments if (tc.arguments is string) else (tc.arguments | tojson)) -%}
        {%- if loop.first -%}
          {{- '<tool_call>\n{"name": "' ~ tc.name ~ '", "arguments": ' ~ args_json ~ '}\n</tool_call>' -}}
        {%- else -%}
          {{- '\n<tool_call>\n{"name": "' ~ tc.name ~ '", "arguments": ' ~ args_json ~ '}\n</tool_call>' -}}
        {%- endif -%}
      {%- endfor -%}
    {%- endif -%}
    {{- '<|eot_id|>' -}}{%- endgeneration -%}
  {# --- tool messages are wrapped as synthetic user messages with <tool_response> --- #}
  {%- elif message.role == "tool" -%}
    {%- set open_user = (loop.first or (loop.index0 > 0 and messages[loop.index0 - 1].role != "tool")) -%}
    {%- set close_user = (loop.last or (loop.index0 < messages|length - 1 and messages[loop.index0 + 1].role != "tool")) -%}

    {%- if open_user -%}
      {%- set header = '<|start_header_id|>user<|end_header_id|>\n' -%}
      {%- if not emit.started -%}{%- set header = bos_token ~ header -%}{%- set emit.started = true -%}{%- endif -%}
      {{- header -}}
    {%- endif -%}
    {%- if open_user -%}
      {{- '<tool_response>\n' -}}
    {%- else -%}
      {{- '\n<tool_response>\n' -}}
    {%- endif -%}
    {{- content -}}
    {{- '\n</tool_response>' -}}

    {%- if close_user -%}
      {{- '<|eot_id|>' -}}
    {%- endif -%}
  {%- endif -%}
{%- endfor -%}

{# ---------- Add generation prompt header for the model to continue ---------- #}
{%- if add_generation_prompt -%}
  {%- set tail = '<|start_header_id|>assistant<|end_header_id|>\n' -%}
  {{- tail -}}
{%- endif -%}