fix(ali): stop injecting top_p into requests that omit it (#6674)

relay/channel/ali/text.go

@@ -18,11 +18,19 @@ func requestOpenAI2Ali(request dto.GeneralOpenAIRequest, upstreamModelName strin
 		request.ThinkingBudget = nil
 	}
 
-	topP := lo.FromPtrOr(request.TopP, 0)
-	if topP >= 1 {
-		request.TopP = lo.ToPtr(0.999)
-	} else if topP <= 0 {
-		request.TopP = lo.ToPtr(0.001)
+	// DashScope rejects top_p at the 0 and 1 boundaries, so an explicit value is
+	// clamped into the open interval. The clamp stays at two decimals because
+	// some models on the platform reject a third decimal with
+	// "top_p参数非法：限制小数点[2]位".
+	//
+	// A request that omits top_p is left untouched: injecting a value would
+	// silently replace the model's own default with near-greedy decoding.
+	if request.TopP != nil {
+		if *request.TopP >= 1 {
+			request.TopP = lo.ToPtr(0.99)
+		} else if *request.TopP <= 0 {
+			request.TopP = lo.ToPtr(0.01)
+		}
 	}
 	return &request
 }

relay/channel/ali/text_test.go

@@ -0,0 +1,59 @@
+package ali
+
+import (
+	"testing"
+
+	"github.com/QuantumNous/new-api/relaykit/dto"
+	"github.com/samber/lo"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestRequestOpenAI2AliTopP(t *testing.T) {
+	tests := []struct {
+		name string
+		topP *float64
+		want *float64
+	}{
+		{
+			name: "omitted top_p is not injected",
+			topP: nil,
+			want: nil,
+		},
+		{
+			name: "in-range top_p is preserved",
+			topP: lo.ToPtr(0.8),
+			want: lo.ToPtr(0.8),
+		},
+		{
+			name: "top_p of 1 is clamped to two decimals",
+			topP: lo.ToPtr(1.0),
+			want: lo.ToPtr(0.99),
+		},
+		{
+			name: "top_p above 1 is clamped to two decimals",
+			topP: lo.ToPtr(1.5),
+			want: lo.ToPtr(0.99),
+		},
+		{
+			name: "top_p of 0 is clamped to two decimals",
+			topP: lo.ToPtr(0.0),
+			want: lo.ToPtr(0.01),
+		},
+		{
+			name: "negative top_p is clamped to two decimals",
+			topP: lo.ToPtr(-0.3),
+			want: lo.ToPtr(0.01),
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := requestOpenAI2Ali(dto.GeneralOpenAIRequest{
+				Model: "qwen-plus",
+				TopP:  tt.topP,
+			}, "qwen-plus")
+
+			assert.Equal(t, tt.want, got.TopP)
+		})
+	}
+}