chat : Align Laguna-S-2.1 chat template to huggingface (#26232)

models/templates/poolside-Laguna-S-2.1.jinja

@@ -1,8 +1,9 @@
 {#- Iteration on laguna_glm_thinking_v8/chat_template.jinja -#}
 {#- No formatting instructions -#}
 {{- "〈|EOS|〉" -}}
-{%- set enable_thinking = enable_thinking | default(false) -%}
+{%- set enable_thinking = enable_thinking | default(true) -%}
 {%- set add_generation_prompt = add_generation_prompt | default(false) -%}
+{%- set preserve_thinking = preserve_thinking | default(false) -%}
 
 {#- ───── header (system message) ───── -#}
 {#- A caller-supplied system message with empty content opts out of the default below, producing no <system> block — used to train without a system message. -#}
@@ -51,7 +52,7 @@
         {%- set reasoning_content = message.reasoning_content -%}
       {%- endif -%}
       {#- Display reasoning content for all messages if enable_thinking -#}
-      {%- if enable_thinking -%}
+      {%- if enable_thinking or preserve_thinking -%}
         {{- '<think>' + reasoning_content + '</think>' -}}
       {%- else -%}
         {{- '</think>' -}}

tests/test-chat-auto-parser.cpp

@@ -63,6 +63,7 @@ static void test_laguna_tool_format(testing & t);
 static void test_laguna_s_analysis(testing & t);
 static void test_laguna_s_reasoning_detection(testing & t);
 static void test_laguna_s_tool_format(testing & t);
+static void test_laguna_s_preserve_reasoning(testing & t);
 static void test_laguna_xs2_analysis(testing & t);
 static void test_laguna_xs2_reasoning_detection(testing & t);
 static void test_laguna_xs2_tool_format(testing & t);
@@ -1451,9 +1452,14 @@ static void test_laguna_s_tool_format(testing & t) {
     analysis.analyze_template(tmpl);
     t.assert_equal("Laguna-S(v8) arg_value_suffix should be '</arg_value>'", "</arg_value>", analysis.tools.arguments.value_suffix);
 }
+static void test_laguna_s_preserve_reasoning(testing & t) {
+    common_chat_template tmpl = load_laguna_s_template(t);
+    t.assert_true("Laguna-S(v8) supports preserving reasoning", tmpl.original_caps().supports_preserve_reasoning);
+}
 static void test_laguna_s_analysis(testing & t) {
     t.test("Laguna-S(v8) reasoning detection", test_laguna_s_reasoning_detection);
     t.test("Laguna-S(v8) tool format", test_laguna_s_tool_format);
+    t.test("Laguna-S(v8) preserve reasoning", test_laguna_s_preserve_reasoning);
 }
 
 static common_chat_template load_laguna_xs2_template(testing & t) {