DeepSeek V3.1 fix reasoning_format none

Author: createthis

common/chat.cpp

@@ -1458,6 +1458,11 @@ static void common_chat_parse_deepseek_v3_1(common_chat_msg_parser & builder) {
         // </think><｜tool▁calls▁begin｜><｜tool▁call▁begin｜>function<｜tool▁sep｜>NAME\n```json\nJSON\n```<｜tool▁call▁end｜><｜tool▁calls▁end｜>
         common_chat_parse_deepseek_v3_1_content(builder);
     } else {
+        if (builder.syntax().reasoning_format == COMMON_REASONING_FORMAT_NONE) {
+          LOG_DBG("%s: reasoning_format none, adding content\n", __func__);
+          common_chat_parse_deepseek_v3_1_content(builder);
+          return;
+        }
         // If no reasoning tags found, check if we should treat everything as reasoning
         if (builder.syntax().thinking_forced_open) {
             // If thinking is forced open but no tags found, treat everything as reasoning

tests/test-chat-parser.cpp

@@ -114,10 +114,26 @@ static void test_reasoning() {
         /* .thinking_forced_open = */ true,
         /* .parse_tool_calls = */ true,
     };
+    const std::string variant("deepseek_v3_1_reasoning_format_deepseek");
     common_chat_msg_parser builder("REASONING</think>ok", /* is_partial= */ false, syntax);
-    assert_equals(true, builder.try_parse_reasoning("<think>", "</think>"));
-    assert_equals(std::string("REASONING"), builder.result().reasoning_content);
-    assert_equals(std::string("ok"), builder.consume_rest());
+    assert_equals(variant, true, builder.try_parse_reasoning("<think>", "</think>"));
+    assert_equals(variant, std::string("REASONING"), builder.result().reasoning_content);
+    assert_equals(variant, std::string("ok"), builder.consume_rest());
+  }
+  // Test DeepSeek V3.1 parsing - reasoning_format none - reasoning content followed by "</think>" and then regular content
+  {
+    common_chat_syntax syntax = {
+        /* .format = */ COMMON_CHAT_FORMAT_DEEPSEEK_V3_1,
+        /* .reasoning_format = */ COMMON_REASONING_FORMAT_NONE,
+        /* .reasoning_in_content = */ false,
+        /* .thinking_forced_open = */ true,
+        /* .parse_tool_calls = */ true,
+    };
+    const std::string variant("deepseek_v3_1_reasoning_format_none");
+    const std::string input = "REASONING</think>ok";
+    auto msg = common_chat_parse(input, false, syntax);
+    assert_equals(variant, std::string("REASONING</think>ok"), msg.content);
+    assert_equals(variant, std::string(""), msg.reasoning_content);
   }
 }
 

tests/test-chat.cpp

@@ -1778,6 +1778,19 @@ static void test_template_output_parsers() {
                     /* .reasoning_in_content = */ false,
                     /* .thinking_forced_open = */ true,
                 }));
+        // variant: thinking forced open, reasoning_format none
+        assert_msg_equals(
+            simple_assist_msg("REASONING</think>ok", ""),
+            common_chat_parse(
+                "REASONING</think>ok",
+                /* is_partial= */ false,
+                {
+                    COMMON_CHAT_FORMAT_DEEPSEEK_V3_1,
+                    /* .reasoning_format = */ COMMON_REASONING_FORMAT_NONE,
+                    /* .reasoning_in_content = */ false,
+                    /* .thinking_forced_open = */ true,
+                    /* .parse_tool_calls = */ true,
+                }));
         // variant: happy path for when it works as the model card says it should
         assert_msg_equals(
             simple_assist_msg("", "", "get_time", "{\"city\":\"Tokyo\"}"),