From 0cc5b14959ee3a813bd787baaef50a170493547a Mon Sep 17 00:00:00 2001
From: Aldehir Rojas <hello@alde.dev>
Date: Tue, 25 Aug 2026 09:33:00 -0500
Subject: [PATCH] chat : scope qwen3-coder workarounds (#27679)

---
 common/chat.cpp | 27 +++++++++++++++++----------
 1 file changed, 17 insertions(+), 10 deletions(-)

diff --git a/common/chat.cpp b/common/chat.cpp
index 24618d35a..743ecde0a 100644
--- a/common/chat.cpp
+++ b/common/chat.cpp
@@ -1177,6 +1177,8 @@ static common_chat_params common_chat_params_init_qwen3_coder(const common_chat_
         "</tool_call>",
     };
 
+    auto is_qwen3_coder  = !supports_reasoning;
+
     if (supports_reasoning) {
         data.thinking_start_tag = "<think>";
         // Support both </think> and <tool_call> as reasoning end sequences.
@@ -1217,13 +1219,15 @@ static common_chat_params common_chat_params_init_qwen3_coder(const common_chat_
 
     std::vector<std::string> tool_call_starts = { "<tool_call>" };
 
-    // Match complete <function=name> opener for Qwen3-Coder models that occasionally omit the
-    // starting <tool_call>. The model may hallucinate a tool name, but it is preferable over
-    // constraining on <function which may occur in valid content generation, e.g. #include <functional>
-    foreach_function(inputs.tools, [&](const json & tool) {
-        const std::string name = tool.at("function").at("name");
-        tool_call_starts.push_back("<function=" + name + ">");
-    });
+    if (is_qwen3_coder) {
+        // Match complete <function=name> opener for Qwen3-Coder models that occasionally omit the
+        // starting <tool_call>. The model may hallucinate a tool name, but it is preferable over
+        // constraining on <function which may occur in valid content generation, e.g. #include <functional>
+        foreach_function(inputs.tools, [&](const json & tool) {
+            const std::string name = tool.at("function").at("name");
+            tool_call_starts.push_back("<function=" + name + ">");
+        });
+    }
 
     auto parser = build_chat_peg_parser([&](common_chat_peg_builder & p) {
         auto generation_prompt = p.literal(GEN_PREFIX);
@@ -1288,10 +1292,13 @@ static common_chat_params common_chat_params_init_qwen3_coder(const common_chat_
 
             auto min_calls = inputs.tool_choice == COMMON_CHAT_TOOL_CHOICE_REQUIRED ? 1 : 0;
 
+            auto tool_call_body = tool_choice + "</tool_call>" + p.space();
+            auto tool_call      = p.rule("tool-call", "<tool_call>\n" + tool_call_body);
+
             // Qwen3-Coder models may occasionally omit the <tool_call> token.
-            auto tool_call_body  = tool_choice + "</tool_call>" + p.space();
-            auto tool_call_first = p.rule("tool-call-first", p.optional(p.literal("<tool_call>\n")) + tool_call_body);
-            auto tool_call       = p.rule("tool-call", "<tool_call>\n" + tool_call_body);
+            auto tool_call_first = is_qwen3_coder ?
+                p.rule("tool-call-first", p.optional(p.literal("<tool_call>\n")) + tool_call_body) :
+                tool_call;
 
             auto calls      = inputs.parallel_tool_calls ? tool_call_first + p.zero_or_more(tool_call) : tool_call_first;
             auto tool_calls = p.trigger_rule("tool-call-root", p.repeat(calls, min_calls, 1));