fix(claude): prevent index out of range panic when message Content is empty

components/model/claude/claude.go

@@ -627,17 +627,21 @@ func (cm *ChatModel) populateInput(params *anthropic.MessageNewParams, system []
 			return fmt.Errorf("convert schema message fail: %w", err)
 		}
 
-		if ctrl := msgParam.Content[len(msgParam.Content)-1].GetCacheControl(); ctrl != nil && ctrl.Type != "" {
-			hasSetMsgBreakPoint = true
+		if len(msgParam.Content) > 0 {
+			if ctrl := msgParam.Content[len(msgParam.Content)-1].GetCacheControl(); ctrl != nil && ctrl.Type != "" {
+				hasSetMsgBreakPoint = true
+			}
 		}
 
 		msgParams = append(msgParams, msgParam)
 	}
 
 	if !hasSetMsgBreakPoint && specOptions.AutoCacheControl != nil {
 		lastMsgParam := msgParams[len(msgParams)-1]
-		lastBlock := lastMsgParam.Content[len(lastMsgParam.Content)-1]
-		populateContentBlockBreakPoint(lastBlock, specOptions.AutoCacheControl)
+		if len(lastMsgParam.Content) > 0 {
+			lastBlock := lastMsgParam.Content[len(lastMsgParam.Content)-1]
+			populateContentBlockBreakPoint(lastBlock, specOptions.AutoCacheControl)
+		}
 	}
 
 	params.Messages = msgParams

components/model/claude/claude_test.go

@@ -246,6 +246,35 @@ func TestClaude(t *testing.T) {
 		assert.NoError(t, err)
 		assert.Equal(t, "I see a beautiful sunset image", resp.Content)
 	})
+
+	mockey.PatchConvey("assistant message with tool calls but empty content should not panic", t, func() {
+		resp, err := model.genMessageNewParams([]*schema.Message{
+			schema.UserMessage("What's the weather in Paris?"),
+			schema.AssistantMessage("", []schema.ToolCall{
+				{
+					ID: "call_1",
+					Function: schema.FunctionCall{
+						Name:      "get_weather",
+						Arguments: `{"city":"Paris"}`,
+					},
+				},
+			}),
+			schema.ToolMessage(`{"temperature": 20}`, "call_1"),
+		})
+		assert.NoError(t, err)
+		assert.Len(t, resp.Messages, 3)
+	})
+
+	mockey.PatchConvey("message with empty content should not panic", t, func() {
+		resp, err := model.genMessageNewParams([]*schema.Message{
+			{Role: schema.User, Content: "hello"},
+			{Role: schema.Assistant},
+			{Role: schema.User, Content: "world"},
+		})
+		assert.NoError(t, err)
+		assert.Len(t, resp.Messages, 3)
+		assert.Empty(t, resp.Messages[1].Content)
+	})
 }
 
 func clearAnthropicAuthEnv(t *testing.T) {