feat: implement decision-based routing with plugin architecture

Signed-off-by: bitliu <[email protected]>

Author: Xunzhuo

src/semantic-router/pkg/extproc/req_filter_classification.go

@@ -76,8 +76,16 @@ func (r *OpenAIRouter) performDecisionEvaluationAndModelSelection(originalModel
 
 	// Select best model from the decision's ModelRefs
 	if len(result.Decision.ModelRefs) > 0 {
-		selectedModel = result.Decision.ModelRefs[0].Model
-		logging.Infof("Selected model from decision %s: %s", decisionName, selectedModel)
+		modelRef := result.Decision.ModelRefs[0]
+		// Use LoRA name if specified, otherwise use the base model name
+		selectedModel = modelRef.Model
+		if modelRef.LoRAName != "" {
+			selectedModel = modelRef.LoRAName
+			logging.Infof("Selected model from decision %s: %s (LoRA adapter for base model %s)",
+				decisionName, selectedModel, modelRef.Model)
+		} else {
+			logging.Infof("Selected model from decision %s: %s", decisionName, selectedModel)
+		}
 
 		// Determine reasoning mode from the best model's configuration
 		if result.Decision.ModelRefs[0].UseReasoning != nil {