diff --git a/internal/ai/llm.go b/internal/ai/llm.go
index 34a58da..8746669 100644
--- a/internal/ai/llm.go
+++ b/internal/ai/llm.go
@@ -59,7 +59,7 @@ func (s *llm) ChatWithConfig(ctx context.Context, config models.AIConfig, system
 	if config.MaxOutputTokens > 0 {
 		params.MaxCompletionTokens = openai.Int(int64(config.MaxOutputTokens))
 	}
-	applyProviderSpecificChatParams(params, config)
+	applyProviderSpecificChatParams(&params, config)
 
 	client := newOpenAIClient(config)
 	chatResp, err := client.Chat.Completions.New(ctx, params)
@@ -80,7 +80,10 @@ func (s *llm) ChatWithConfig(ctx context.Context, config models.AIConfig, system
 	}, nil
 }
 
-func applyProviderSpecificChatParams(params openai.ChatCompletionNewParams, config models.AIConfig) {
+func applyProviderSpecificChatParams(params *openai.ChatCompletionNewParams, config models.AIConfig) {
+	if params == nil {
+		return
+	}
 	if isDashScopeQwenThinkingModel(config) {
 		params.SetExtraFields(map[string]any{
 			"enable_thinking": false,
diff --git a/internal/ai/llm_test.go b/internal/ai/llm_test.go
new file mode 100644
index 0000000..4774f38
--- /dev/null
+++ b/internal/ai/llm_test.go
@@ -0,0 +1,43 @@
+package ai
+
+import (
+	"encoding/json"
+	"testing"
+
+	openai "github.com/openai/openai-go/v3"
+	"github.com/openai/openai-go/v3/shared"
+
+	"agent-desk/internal/models"
+)
+
+func TestApplyProviderSpecificChatParamsIncludesDashScopeThinkingFlag(t *testing.T) {
+	params := openai.ChatCompletionNewParams{
+		Messages: []openai.ChatCompletionMessageParamUnion{
+			{
+				OfUser: &openai.ChatCompletionUserMessageParam{
+					Content: openai.ChatCompletionUserMessageParamContentUnion{
+						OfString: openai.String("hello"),
+					},
+				},
+			},
+		},
+		Model: shared.ChatModel("qwen3.5-plus"),
+	}
+
+	applyProviderSpecificChatParams(&params, models.AIConfig{
+		BaseURL:   "https://dashscope.aliyuncs.com/compatible-mode/v1",
+		ModelName: "qwen3.5-plus",
+	})
+
+	raw, err := json.Marshal(params)
+	if err != nil {
+		t.Fatalf("marshal params: %v", err)
+	}
+	var body map[string]any
+	if err := json.Unmarshal(raw, &body); err != nil {
+		t.Fatalf("unmarshal params: %v", err)
+	}
+	if got, ok := body["enable_thinking"].(bool); !ok || got {
+		t.Fatalf("expected enable_thinking=false in request body, got body=%s", raw)
+	}
+}