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UPSTREAM PR #19635: common : fix Step-3.5-Flash format detection and thinking support #1182

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UPSTREAM PR #19635: common : fix Step-3.5-Flash format detection and thinking support #1182

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db38820
common : fix Step-3.5-Flash format detection and thinking support
jesseposner Feb 15, 2026
ac0f256
chat : route Step-3.5-Flash to Nemotron v3 PEG parser, add tests
jesseposner Feb 15, 2026
bdc1dda
chat : remove dead thinking code from qwen3_coder_xml
jesseposner Feb 16, 2026
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10 changes: 5 additions & 5 deletions common/chat.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3129,15 +3129,15 @@ static common_chat_params common_chat_templates_apply_jinja(
}

// Qwen3-Coder XML format detection (must come before Hermes 2 Pro)
// Detect via explicit XML markers unique to Qwen3-Coder to avoid false positives in other templates.
// Require presence of <tool_call>, <function=...>, and <parameter=...> blocks.
// Detect via XML markers: <tool_call>, <function=...>, and <parameter=...> blocks.
// Also matches Step-3.5-Flash and Nemotron 3 Nano which use the same output format.
if (src.find("<tool_call>") != std::string::npos &&
src.find("<function>") != std::string::npos &&
src.find("<function=") != std::string::npos &&
src.find("<parameters>") != std::string::npos &&
src.find("<parameter=") != std::string::npos) {
workaround::func_args_not_string(params.messages);
// Nemotron 3 Nano 30B A3B
// Models with <think> support (Step-3.5-Flash, Nemotron 3 Nano) use the
// Nemotron v3 PEG parser for streaming and schema-aware parameter parsing.
// Qwen3-Coder has no <think> in its template.
if (src.find("<think>") != std::string::npos) {
return common_chat_params_init_nemotron_v3(tmpl, params);
}
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80 changes: 80 additions & 0 deletions models/templates/stepfun-ai-Step-3.5-Flash.jinja
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Original file line number Diff line number Diff line change
@@ -0,0 +1,80 @@
{% macro render_content(content) %}{% if content is none %}{{- '' }}{% elif content is string %}{{- content }}{% elif content is mapping %}{{- content['value'] if 'value' in content else content['text'] }}{% elif content is iterable %}{% for item in content %}{% if item.type == 'text' %}{{- item['value'] if 'value' in item else item['text'] }}{% elif item.type == 'image' %}<im_patch>{% endif %}{% endfor %}{% endif %}{% endmacro %}
{{bos_token}}{%- if tools %}
{{- '<|im_start|>system\n' }}
{%- if messages[0].role == 'system' %}
{{- render_content(messages[0].content) + '\n\n' }}
{%- endif %}
{{- "# Tools\n\nYou have access to the following functions in JSONSchema format:\n\n<tools>" }}
{%- for tool in tools %}
{{- "\n" }}
{{- tool | tojson(ensure_ascii=False) }}
{%- 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=...>\n...\n</function> block must be nested within <tool_call>\n...\n</tool_call> XML tags\n- Required parameters MUST be specified\n</IMPORTANT><|im_end|>\n" }}
{%- else %}
{%- if messages[0].role == 'system' %}
{{- '<|im_start|>system\n' + render_content(messages[0].content) + '<|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" and render_content(message.content) is string and not(render_content(message.content).startswith('<tool_response>') and render_content(message.content).endswith('</tool_response>')) %}
{%- set ns.multi_step_tool = false %}
{%- set ns.last_query_index = index %}
{%- endif %}
{%- endfor %}
{%- for message in messages %}
{%- set content = render_content(message.content) %}
{%- if (message.role == "user") or (message.role == "system" and not loop.first) %}
{%- set role_name = 'observation' if (message.role == "system" and not loop.first and message.name == 'observation') else message.role %}
{{- '<|im_start|>' + role_name + '\n' + content + '<|im_end|>' + '\n' }}
{%- elif message.role == "assistant" %}
{%- if message.reasoning_content is string %}
{%- set reasoning_content = render_content(message.reasoning_content) %}
{%- else %}
{%- if '</think>' in content %}
{%- set reasoning_content = content.split('</think>')[0].rstrip('\n').split('<think>')[-1].lstrip('\n') %}
{%- set content = content.split('</think>')[-1].lstrip('\n') %}
{%- else %}
{%- set reasoning_content = '' %}
{%- endif %}
{%- endif %}
{%- if loop.index0 > ns.last_query_index %}
{{- '<|im_start|>' + message.role + '\n<think>\n' + reasoning_content + '\n</think>\n' + content }}
{%- else %}
{{- '<|im_start|>' + message.role + '\n' + content }}
{%- endif %}
{%- if message.tool_calls %}
{%- for tool_call in message.tool_calls %}
{%- if tool_call.function is defined %}
{%- set tool_call = tool_call.function %}
{%- endif %}
{{- '<tool_call>\n<function=' + tool_call.name + '>\n' }}
{%- if tool_call.arguments is defined %}
{%- set arguments = tool_call.arguments %}
{%- for args_name, args_value in arguments|items %}
{{- '<parameter=' + args_name + '>\n' }}
{%- set args_value = args_value | tojson(ensure_ascii=False) | safe if args_value is mapping or (args_value is sequence and args_value is not string) else args_value | string %}
{{- args_value }}
{{- '\n</parameter>\n' }}
{%- endfor %}
{%- endif %}
{{- '</function>\n</tool_call>' }}
{%- endfor %}
{%- endif %}
{{- '<|im_end|>\n' }}
{%- elif message.role == "tool" %}
{%- if loop.first or (messages[loop.index0 - 1].role != "tool") %}
{{- '<|im_start|>tool_response\n' }}
{%- endif %}
{{- '<tool_response>' }}
{{- content }}
{{- '</tool_response>' }}
{%- if loop.last or (messages[loop.index0 + 1].role != "tool") %}
{{- '<|im_end|>\n' }}
{%- endif %}
{%- endif %}
{%- endfor %}
{%- if add_generation_prompt %}
{{- '<|im_start|>assistant\n<think>\n' }}
{%- endif %}
212 changes: 212 additions & 0 deletions tests/test-chat.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3553,6 +3553,28 @@ Hey there!<|im_end|>
auto grammar = build_grammar(params.grammar);
GGML_ASSERT(grammar && "Failed to build Qwen3-Coder grammar with union types");
}

{
// Step-3.5-Flash template: uses same XML output format as Qwen3-Coder and Nemotron v3,
// but with <think> support. Routes to the Nemotron v3 PEG parser for streaming and
// schema-aware parameter parsing.
auto tmpls = read_templates("models/templates/stepfun-ai-Step-3.5-Flash.jinja");
assert_equals(COMMON_CHAT_FORMAT_PEG_CONSTRUCTED, common_chat_templates_apply(tmpls.get(), inputs_tools).format);

// Grammar and PEG parser should be generated with thinking_forced_open
{
common_chat_templates_inputs inputs;
inputs.messages = { message_user };
inputs.tools = { special_function_tool };
auto params = common_chat_templates_apply(tmpls.get(), inputs);
assert_equals(COMMON_CHAT_FORMAT_PEG_CONSTRUCTED, params.format);
assert_equals(true, params.thinking_forced_open);
assert_equals(false, params.grammar.empty());
assert_equals(false, params.parser.empty());
auto grammar = build_grammar(params.grammar);
GGML_ASSERT(grammar && "Failed to build Step-3.5-Flash grammar");
}
}
}

static void test_template_output_peg_parsers() {
Expand Down Expand Up @@ -3799,6 +3821,196 @@ static void test_template_output_peg_parsers() {
});
}

{
// Step-3.5-Flash (uses Nemotron v3 PEG parser with thinking_forced_open)
// Unlike Nemotron, Step-3.5-Flash always emits <think> regardless of enable_thinking,
// so all inputs must include a </think> delimiter.
auto tmpls = read_templates("models/templates/stepfun-ai-Step-3.5-Flash.jinja");

// Test basic message with reasoning
test_peg_parser(tmpls.get(), [&](auto & t) {
t.input = "I'm\nthinking\n</think>\nHello, world!\nWhat's up?";
t.params.reasoning_format = COMMON_REASONING_FORMAT_AUTO;

t.expect = message_assist_thoughts;
});

// Test basic message without thinking content
test_peg_parser(tmpls.get(), [&](auto & t) {
t.input = "</think>\nHello, world!\nWhat's up?";
t.params.reasoning_format = COMMON_REASONING_FORMAT_AUTO;

t.expect = message_assist;
});

// Test tool call without thinking content
test_peg_parser(tmpls.get(), [&](auto & t) {
t.input =
"</think>\n"
"<tool_call>\n"
"<function=special_function>\n"
"<parameter=arg1>\n"
"1\n"
"</parameter>\n"
"</function>\n"
"</tool_call>";
t.params.reasoning_format = COMMON_REASONING_FORMAT_AUTO;
t.params.tools = {special_function_tool};

t.expect = message_assist_call;
});

// Test tool call with thinking
test_peg_parser(tmpls.get(), [&](auto & t) {
t.input =
"I'm\nthinking\n</think>\n"
"<tool_call>\n"
"<function=special_function>\n"
"<parameter=arg1>\n"
"1\n"
"</parameter>\n"
"</function>\n"
"</tool_call>";
t.params.reasoning_format = COMMON_REASONING_FORMAT_AUTO;
t.params.tools = {special_function_tool};

t.expect = message_assist_call_thoughts;
});

// Test parallel tool calls with thinking
test_peg_parser(tmpls.get(), [&](auto & t) {
t.input =
"I'm\nthinking\n</think>\n"
"<tool_call>\n"
"<function=special_function>\n"
"<parameter=arg1>\n"
"1\n"
"</parameter>\n"
"</function>\n"
"</tool_call>\n"
"<tool_call>\n"
"<function=special_function_with_opt>\n"
"<parameter=arg1>\n"
"1\n"
"</parameter>\n"
"<parameter=arg2>\n"
"2\n"
"</parameter>\n"
"</function>\n"
"</tool_call>";
t.params.reasoning_format = COMMON_REASONING_FORMAT_AUTO;
t.params.parallel_tool_calls = true;
t.params.tools = {special_function_tool, special_function_tool_with_optional_param};

t.expect.reasoning_content = "I'm\nthinking";
t.expect.tool_calls = {{
/* .name = */ "special_function",
/* .arguments = */ R"({"arg1": 1})",
/* .id = */ {},
}, {
/* .name = */ "special_function_with_opt",
/* .arguments = */ R"({"arg1": 1, "arg2": 2})",
/* .id = */ {},
}};
});

// Test parallel tool calls without thinking content
test_peg_parser(tmpls.get(), [&](auto & t) {
t.input =
"</think>\n"
"<tool_call>\n"
"<function=special_function>\n"
"<parameter=arg1>\n"
"1\n"
"</parameter>\n"
"</function>\n"
"</tool_call>\n"
"<tool_call>\n"
"<function=special_function_with_opt>\n"
"<parameter=arg1>\n"
"1\n"
"</parameter>\n"
"<parameter=arg2>\n"
"2\n"
"</parameter>\n"
"</function>\n"
"</tool_call>";
t.params.reasoning_format = COMMON_REASONING_FORMAT_AUTO;
t.params.parallel_tool_calls = true;
t.params.tools = {special_function_tool, special_function_tool_with_optional_param};

t.expect.tool_calls = {{
/* .name = */ "special_function",
/* .arguments = */ R"({"arg1": 1})",
/* .id = */ {},
}, {
/* .name = */ "special_function_with_opt",
/* .arguments = */ R"({"arg1": 1, "arg2": 2})",
/* .id = */ {},
}};
});

// Test tool call with code string parameter
test_peg_parser(tmpls.get(), [&](auto & t) {
t.input =
"</think>\n"
"<tool_call>\n"
"<function=python>\n"
"<parameter=code>\n"
"def hello():\n"
" print(\"Hello, world!\")\n"
"\n"
"hello()\n"
"</parameter>\n"
"</function>\n"
"</tool_call>";
t.params.reasoning_format = COMMON_REASONING_FORMAT_AUTO;
t.params.tools = {python_tool};

t.expect.tool_calls = {{
/* .name = */ "python",
/* .arguments = */ "{\"code\": \"def hello():\\n print(\\\"Hello, world!\\\")\\n\\nhello()\"}",
/* .id = */ {},
}};
});

// Test tool call with string parameter and no closing </parameter> tag
test_peg_parser(tmpls.get(), [&](auto & t) {
t.input =
"</think>\n"
"<tool_call>\n"
"<function=python>\n"
"<parameter=code>\n"
"def hello():\n"
" print(\"Hello, world!\")\n"
"\n"
"hello()\n"
"</function>\n"
"</tool_call>";
t.params.reasoning_format = COMMON_REASONING_FORMAT_AUTO;
t.params.tools = {python_tool};

t.expect.tool_calls = {{
/* .name = */ "python",
/* .arguments = */ "{\"code\": \"def hello():\\n print(\\\"Hello, world!\\\")\\n\\nhello()\"}",
/* .id = */ {},
}};
});

// Test response format (JSON schema with thinking)
test_peg_parser(tmpls.get(), [&](auto & t) {
t.input =
"I need to output the invoice details in JSON\n"
"</think>\n"
R"({"amount": 123.45, "date": "2025-12-03"})";
t.params.reasoning_format = COMMON_REASONING_FORMAT_AUTO;
t.params.json_schema = invoice_schema;

t.expect.reasoning_content = "I need to output the invoice details in JSON";
t.expect.content = R"({"amount": 123.45, "date": "2025-12-03"})";
});
}

{
// Solar-Open-100B
auto tmpls = read_templates("models/templates/upstage-Solar-Open-100B.jinja");
Expand Down
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