chat : nemotron thinking & toolcalling support (#15676)

* feat: nemotron thinking & toolcalling support

* Trailing whitespaces

* Corrected template for Nemotron

* Template and parser fixes

* Final template and grammar changes

* Whitespace

* Always do lazy grammar processing since </think> tag will always be there.

* Allow extra content after toolcall

* Whitespace

* New tests: thinking + tools, tools + content, thinking + tools + content (new!)

* Whitespace

* Remove cURL test script

common/chat.cpp

@@ -623,6 +623,7 @@ const char * common_chat_format_name(common_chat_format format) {
         case COMMON_CHAT_FORMAT_GRANITE: return "Granite";
         case COMMON_CHAT_FORMAT_GPT_OSS: return "GPT-OSS";
         case COMMON_CHAT_FORMAT_SEED_OSS: return "Seed-OSS";
+        case COMMON_CHAT_FORMAT_NEMOTRON_V2: return "Nemotron V2";
         default:
             throw std::runtime_error("Unknown chat format");
     }
@@ -1184,6 +1185,67 @@ static common_chat_params common_chat_params_init_llama_3_x(const common_chat_te
     });
     return data;
 }
+
+static common_chat_params common_chat_params_init_nemotron_v2(const common_chat_template & tmpl, const struct templates_params & inputs) {
+    common_chat_params data;
+
+    // Generate the prompt using the apply() function with the template
+    data.prompt = apply(tmpl, inputs);
+    data.format = COMMON_CHAT_FORMAT_NEMOTRON_V2;
+
+    // Handle thinking tags appropriately based on inputs.enable_thinking
+    if (string_ends_with(data.prompt, "<think>\n")) {
+        if (!inputs.enable_thinking) {
+            data.prompt += "</think>";
+        } else {
+            data.thinking_forced_open = true;
+        }
+    }
+
+    // When tools are present, build grammar for the <TOOLCALL> format, similar to CommandR, but without tool call ID
+    if (!inputs.tools.is_null() && inputs.tools.is_array() && !inputs.tools.empty()) {
+        data.grammar_lazy = true;
+        data.grammar      = build_grammar([&](const common_grammar_builder & builder) {
+            auto schemas = json::array();
+            foreach_function(inputs.tools, [&](const json & tool) {
+                const auto & function = tool.at("function");
+                schemas.push_back({
+                    { "type",       "object"                                                   },
+                    { "properties",
+                        {
+                            { "name",
+                            {
+                                { "type", "string" },
+                                { "const", function.at("name") },
+                            } },
+                            { "arguments", function.at("parameters") },
+                        }                                                                        },
+                    { "required",   json::array({ "name", "arguments" }) },
+                });
+            });
+            auto schema = json{
+                        { "type",     "array"                                                         },
+                        { "items",    schemas.size() == 1 ? schemas[0] : json{ { "anyOf", schemas } } },
+                        { "minItems", 1                                                               },
+            };
+            if (!inputs.parallel_tool_calls) {
+                schema["maxItems"] = 1;
+            }
+            builder.add_rule("root",
+                                std::string(data.thinking_forced_open ? "( \"</think>\" space )? " : "") +
+                                    "\"<TOOLCALL>\" " + builder.add_schema("tool_calls", schema) +
+                                    " \"</TOOLCALL>\"");
+        });
+        data.grammar_triggers.push_back({ COMMON_GRAMMAR_TRIGGER_TYPE_PATTERN_FULL,
+            // If thinking_forced_open, then we capture the </think> tag in the grammar,
+            // (important for required tool choice) and in the trigger's first capture (decides what is sent to the grammar)
+            std::string(data.thinking_forced_open ?
+                            "[\\s\\S]*?(</think>\\s*)" :
+                            "(?:<think>[\\s\\S]*?</think>\\s*)?") +
+                "(<TOOLCALL>)[\\s\\S]*" });
+    }
+    return data;
+}
 static void common_chat_parse_llama_3_1(common_chat_msg_parser & builder, bool with_builtin_tools = false) {
     if (!builder.syntax().parse_tool_calls) {
         builder.add_content(builder.consume_rest());
@@ -2060,6 +2122,33 @@ static void common_chat_parse_granite(common_chat_msg_parser & builder) {
     }
 }
 
+static void common_chat_parse_nemotron_v2(common_chat_msg_parser & builder) {
+    // Parse thinking tags
+    builder.try_parse_reasoning("<think>", "</think>");
+    if (!builder.syntax().parse_tool_calls) {
+        builder.add_content(builder.consume_rest());
+        return;
+    }
+
+    // Look for tool calls
+    static const common_regex tool_call_regex(regex_escape("<TOOLCALL>"));
+    if (auto res = builder.try_find_regex(tool_call_regex)) {
+        builder.move_to(res->groups[0].end);
+
+        // Expect JSON array of tool calls
+        auto tool_calls_data = builder.consume_json();
+        if (tool_calls_data.json.is_array()) {
+            if (!builder.try_consume_literal("</TOOLCALL>")) {
+                throw common_chat_msg_partial_exception("Incomplete tool call");
+            }
+            builder.add_tool_calls(tool_calls_data.json);
+        } else {
+            throw common_chat_msg_partial_exception("Incomplete tool call");
+        }
+    }
+    builder.add_content(builder.consume_rest());
+}
+
 static void common_chat_parse_seed_oss(common_chat_msg_parser & builder) {
     // Parse thinking tags first - this handles the main reasoning content
     builder.try_parse_reasoning("<seed:think>", "</seed:think>");
@@ -2293,6 +2382,11 @@ static common_chat_params common_chat_templates_apply_jinja(
         return common_chat_params_init_seed_oss(tmpl, params, inputs);
     }
 
+    // Nemotron v2
+    if (src.find("<SPECIAL_10>") != std::string::npos) {
+        return common_chat_params_init_nemotron_v2(tmpl, params);
+    }
+
     // Use generic handler when mixing tools + JSON schema.
     // TODO: support that mix in handlers below.
     if ((params.tools.is_array() && params.json_schema.is_object())) {
@@ -2454,6 +2548,9 @@ static void common_chat_parse(common_chat_msg_parser & builder) {
         case COMMON_CHAT_FORMAT_SEED_OSS:
             common_chat_parse_seed_oss(builder);
             break;
+        case COMMON_CHAT_FORMAT_NEMOTRON_V2:
+            common_chat_parse_nemotron_v2(builder);
+            break;
         default:
             throw std::runtime_error(std::string("Unsupported format: ") + common_chat_format_name(builder.syntax().format));
     }

common/chat.h

@@ -112,6 +112,7 @@ enum common_chat_format {
     COMMON_CHAT_FORMAT_GRANITE,
     COMMON_CHAT_FORMAT_GPT_OSS,
     COMMON_CHAT_FORMAT_SEED_OSS,
+    COMMON_CHAT_FORMAT_NEMOTRON_V2,
 
     COMMON_CHAT_FORMAT_COUNT, // Not a format, just the # formats
 };

models/templates/NVIDIA-Nemotron-Nano-v2.jinja

@@ -0,0 +1,162 @@
+{%- set ns = namespace(enable_thinking=true) -%}
+{%- for message in messages -%}
+  {%- set content = message['content'] -%}
+  {%- if message['role'] == 'user' or message['role'] == 'system' -%}
+    {%- if '/think' in content -%}
+      {%- set ns.enable_thinking = true -%}
+    {%- elif '/no_think' in content -%}
+      {%- set ns.enable_thinking = false -%}
+    {%- endif -%}
+  {%- endif -%}
+{%- endfor -%}
+
+{%- if messages[0]['role'] != 'system' -%}
+  {%- set ns.non_tool_system_content = '' -%}
+  {{- '<SPECIAL_10>System
+' -}}
+{%- else -%}
+  {%- set ns.non_tool_system_content = (messages[0]['content'] | default('', true)).replace('/think', '').replace('/no_think', '').strip() -%}
+  {{- '<SPECIAL_10>System
+' + ns.non_tool_system_content }}
+{%- endif -%}
+
+{%- if tools -%}
+  {%- if ns.non_tool_system_content is defined and ns.non_tool_system_content != '' -%}
+    {{- '
+
+' -}}
+  {%- endif -%}
+  {{- 'You can use the following tools to assist the user if required:' -}}
+  {{- '
+<AVAILABLE_TOOLS>[' -}}
+  {%- for tool in tools -%}
+    {{- (tool.function if tool.function is defined else tool) | tojson -}}
+    {{- ', ' if not loop.last else '' -}}
+  {%- endfor -%}
+  {{- ']</AVAILABLE_TOOLS>
+
+' -}}
+  {{- 'If you decide to call any tool(s), use the following format:
+' -}}
+  {{- '<TOOLCALL>[{{"name": "tool_name1", "arguments": "tool_args1"}}, ' -}}
+  {{- '{{"name": "tool_name2", "arguments": "tool_args2"}}]</TOOLCALL>
+
+' -}}
+  {{- 'The user will execute tool-calls and return responses from tool(s) in this format:
+' -}}
+  {{- '<TOOL_RESPONSE>[{{"tool_response1"}}, {{"tool_response2"}}]</TOOL_RESPONSE>
+
+' -}}
+  {{- 'Based on the tool responses, you can call additional tools if needed, correct tool calls if any errors are found, or just respond to the user.' -}}
+{%- endif -%}
+{{- '
+
+' -}}
+{%- set messages = messages[1:] if messages[0]['role'] == 'system' else messages -%}
+{%- if messages[-1]['role'] == 'assistant' -%}
+  {%- set ns.last_turn_assistant_content = (messages[-1]['content'] | default('', true)).strip() -%}
+  {%- set ns.last_turn_assistant_tool_calls = messages[-1]['tool_calls'] if 'tool_calls' in messages[-1] else [] -%}
+  {%- set messages = messages[:-1] -%}
+{%- endif -%}
+
+{%- for message in messages %}
+  {%- set content = message['content'] %}
+  {%- if message['role'] == 'user' -%}
+    {{- '<SPECIAL_11>User
+' + (content | default('', true)).replace('/think', '').replace('/no_think', '').strip() + '
+' }}
+  {%- elif message['role'] == 'tool' -%}
+    {%- if loop.first or (messages[loop.index0 - 1].role != 'tool') -%}
+      {{- '<SPECIAL_11>User
+' + '<TOOL_RESPONSE>[' }}
+    {%- endif -%}
+    {{- message['content'] -}}
+    {{- ', ' if not loop.last and (messages[loop.index0 + 1].role == 'tool') else '' -}}
+    {%- if loop.last or (messages[loop.index0 + 1].role != 'tool') -%}
+      {{- ']</TOOL_RESPONSE>' -}}
+    {%- endif -%}
+  {%- elif message['role'] == 'assistant' -%}
+    {%- if content and '</think>' in content -%}
+      {%- set content = (content.split('</think>')[1] | default('', true)).strip() %}
+    {%- endif -%}
+    {{- '<SPECIAL_11>Assistant
+' + ((content | default('', true)).strip() if content is not none else '') }}
+    {%- if message.tool_calls -%}
+      {%- if (content | default('', true)).strip() != '' -%}
+        {{- '
+' -}}
+      {%- endif -%}
+      {{- '<TOOLCALL>[' -}}
+      {%- for call in message.tool_calls -%}
+        {%- set fn = call.function if call.function is defined else call -%}
+        {{- '{"name": "' + fn.name + '", "arguments": ' -}}
+        {%- if fn.arguments is string -%}
+          {{- fn.arguments -}}
+        {%- else -%}
+          {{- fn.arguments | tojson -}}
+        {%- endif -%}
+        {{- '}' + (', ' if not loop.last else '') -}}
+      {%- endfor -%}
+      {{- ']</TOOLCALL>' -}}
+    {%- endif -%}
+    {{- '
+<SPECIAL_12>
+' -}}
+  {%- endif -%}
+{%- endfor -%}
+
+{%- if add_generation_prompt -%}
+  {{- '<SPECIAL_11>Assistant
+' -}}
+  {%- if ns.enable_thinking is defined and ns.enable_thinking is false -%}
+    {{- '<think></think>' -}}
+  {%- else -%}
+    {{- '<think>
+' -}}
+  {%- endif -%}
+  {%- if ns.last_turn_assistant_content is defined and ns.last_turn_assistant_content != '' -%}
+    {{- ns.last_turn_assistant_content -}}
+  {%- endif -%}
+{%- else -%}
+  {%- if ns.last_turn_assistant_content is defined and ns.last_turn_assistant_content != '' -%}
+    {{- '<SPECIAL_11>Assistant
+' -}}
+    {%- if ns.enable_thinking is defined and ns.enable_thinking is false -%}
+      {{- '<think></think>' -}}
+    {%- else -%}
+      {{- '<think>
+' -}}
+    {%- endif -%}
+    {{- ns.last_turn_assistant_content -}}
+    {%- if continue_final_message is defined -%}
+      {%- if continue_final_message is false -%}
+        {{- '
+<SPECIAL_12>
+' -}}
+      {%- endif -%}
+    {%- else -%}
+      {{- '
+<SPECIAL_12>
+' -}}
+    {%- endif -%}
+  {%- endif -%}
+  {%- if ns.last_turn_assistant_tool_calls is defined and ns.last_turn_assistant_tool_calls | length > 0 -%}
+    {{- '<SPECIAL_11>Assistant
+' -}}
+    {{- '<TOOLCALL>[' -}}
+    {%- for call in ns.last_turn_assistant_tool_calls -%}
+      {%- set fn = call.function if call.function is defined else call -%}
+      {{- '{"name": "' + fn.name + '", "arguments": ' -}}
+      {%- if fn.arguments is string -%}
+        {{- fn.arguments -}}
+      {%- else -%}
+        {{- fn.arguments | tojson -}}
+      {%- endif -%}
+      {{- '}' + (', ' if not loop.last else '') -}}
+    {%- endfor -%}
+    {{- ']</TOOLCALL>' -}}
+    {{- '<SPECIAL_12>
+
+' -}}
+ {%- endif -%}
+{%- endif -%}

tests/test-chat.cpp

@@ -420,6 +420,7 @@ const common_chat_msg message_assist_call_empty_args             = simple_assist
 const common_chat_msg message_assist_call_cutoff_args            = simple_assist_msg("", "", "special_function", "{\"arg");
 const common_chat_msg message_assist_call_thoughts               = simple_assist_msg("", "I'm\nthinking", "special_function", "{\"arg1\":1}");
 const common_chat_msg message_assist_call_thoughts_unparsed      = simple_assist_msg("<think>I'm\nthinking</think>\n\n", "", "special_function", "{\"arg1\": 1}");
+const common_chat_msg message_assist_call_thoughts_content       = simple_assist_msg("Hello, world!\nWhat's up?", "I'm\nthinking", "special_function", "{\"arg1\": 1}");
 const common_chat_msg message_assist_call_id                     = simple_assist_msg("", "", "special_function", "{\"arg1\":1}", /* .id = */ "123456789");
 const common_chat_msg message_assist_call_idx                    = simple_assist_msg("", "", "special_function", "{\"arg1\":1}", /* .id = */ "0");
 const common_chat_msg message_assist_thoughts_call_idx           = simple_assist_msg("", "I'm\nthinking", "special_function", "{\"arg1\": 1}", /* id = */ "0");
@@ -436,6 +437,7 @@ static void test_msgs_oaicompat_json_conversion() {
         message_assist_call,
         message_assist_call_thoughts,
         message_assist_call_thoughts_unparsed,
+        message_assist_call_thoughts_content,
         message_assist_call_id,
         message_assist_call_idx,
         message_assist_call_python,
@@ -1755,6 +1757,77 @@ static void test_template_output_parsers() {
                 /* is_partial= */ false,
                 {COMMON_CHAT_FORMAT_SEED_OSS}));
     }
+
+    {
+        auto tmpls = read_templates("models/templates/NVIDIA-Nemotron-Nano-v2.jinja");
+        std::vector<std::string> end_tokens{ "<SPECIAL_12>" };
+
+        assert_equals(COMMON_CHAT_FORMAT_NEMOTRON_V2, common_chat_templates_apply(tmpls.get(), inputs_no_tools).format);
+        assert_equals(COMMON_CHAT_FORMAT_NEMOTRON_V2, common_chat_templates_apply(tmpls.get(), inputs_tools).format);
+
+        // Test parsing regular content
+        assert_msg_equals(message_assist,
+            common_chat_parse(
+                "Hello, world!\nWhat's up?",
+                /* is_partial= */ false,
+                {COMMON_CHAT_FORMAT_NEMOTRON_V2}));
+
+        // Test parsing content with thinking
+        assert_msg_equals(message_assist_thoughts,
+            common_chat_parse(
+                "<think>I'm\nthinking</think>Hello, world!\nWhat's up?",
+                /* is_partial= */ false,
+                {
+                    /* .format = */ COMMON_CHAT_FORMAT_NEMOTRON_V2,
+                    /* .reasoning_format = */ COMMON_REASONING_FORMAT_DEEPSEEK,
+                }));
+
+        // Test parsing tool calls
+        assert_msg_equals(message_assist_call,
+            common_chat_parse(
+                "<TOOLCALL>[{\"name\": \"special_function\", \"arguments\": {\"arg1\": 1}}]</TOOLCALL>",
+                /* is_partial= */ false,
+                {COMMON_CHAT_FORMAT_NEMOTRON_V2}));
+
+        // Test parsing tool calls with thinking
+        assert_msg_equals(message_assist_call_thoughts,
+            common_chat_parse(
+                "<think>I'm\nthinking</think><TOOLCALL>[{\"name\": \"special_function\", \"arguments\": {\"arg1\": 1}}]</TOOLCALL>",
+                /* is_partial= */ false,
+                {
+                    /*  .format = */ COMMON_CHAT_FORMAT_NEMOTRON_V2,
+                    /*  .reasoning_format = */ COMMON_REASONING_FORMAT_DEEPSEEK
+                }));
+
+        // Test tool calls with extra content
+        assert_msg_equals(message_assist_call_content,
+            common_chat_parse(
+                "<TOOLCALL>[{\"name\": \"special_function\", \"arguments\": {\"arg1\": 1}}]</TOOLCALL>Hello, world!\nWhat's up?",
+                /* is_partial= */ false,
+                {COMMON_CHAT_FORMAT_NEMOTRON_V2}
+            ));
+
+        // Test tool calls with extra content AND thinking
+        assert_msg_equals(message_assist_call_thoughts_content,
+            common_chat_parse(
+                "<think>I'm\nthinking</think><TOOLCALL>[{\"name\": \"special_function\", \"arguments\": {\"arg1\": 1}}]</TOOLCALL>Hello, world!\nWhat's up?",
+                /* is_partial= */ false,
+                {
+                    /*  .format = */ COMMON_CHAT_FORMAT_NEMOTRON_V2,
+                    /*  .reasoning_format = */ COMMON_REASONING_FORMAT_DEEPSEEK
+                }));
+
+        // Test template generation for regular content
+        test_templates(tmpls.get(), end_tokens, message_assist, tools,
+                      "Hello, world!\nWhat's up?\n",
+                      /* expect_grammar_triggered= */ false);
+
+        // Test template generation for tool calls
+        test_templates(tmpls.get(), end_tokens, message_assist_call, tools,
+                      "<TOOLCALL>[{\"name\": \"special_function\", \"arguments\": {\"arg1\": 1}}]</TOOLCALL>",
+                      /* expect_grammar_triggered= */ true
+        );
+    }
 }
 
 static void test_msg_diffs_compute() {