feat: implement decision-based routing with plugin architecture

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

Author: Xunzhuo

src/semantic-router/pkg/config/config.go

@@ -3,6 +3,8 @@ package config
 import (
 	"encoding/json"
 	"fmt"
+
+	"github.com/vllm-project/semantic-router/src/semantic-router/pkg/observability/logging"
 )
 
 // ConfigSource defines where to load dynamic configuration from
@@ -609,7 +611,7 @@ func (d *Decision) GetSemanticCacheConfig() *SemanticCachePluginConfig {
 
 	result := &SemanticCachePluginConfig{}
 	if err := unmarshalPluginConfig(config, result); err != nil {
-		// Log error but return nil to maintain backward compatibility
+		logging.Errorf("Failed to unmarshal semantic-cache config: %v", err)
 		return nil
 	}
 	return result
@@ -624,6 +626,7 @@ func (d *Decision) GetJailbreakConfig() *JailbreakPluginConfig {
 
 	result := &JailbreakPluginConfig{}
 	if err := unmarshalPluginConfig(config, result); err != nil {
+		logging.Errorf("Failed to unmarshal jailbreak config: %v", err)
 		return nil
 	}
 	return result
@@ -638,6 +641,7 @@ func (d *Decision) GetPIIConfig() *PIIPluginConfig {
 
 	result := &PIIPluginConfig{}
 	if err := unmarshalPluginConfig(config, result); err != nil {
+		logging.Errorf("Failed to unmarshal pii config: %v", err)
 		return nil
 	}
 	return result
@@ -652,6 +656,7 @@ func (d *Decision) GetSystemPromptConfig() *SystemPromptPluginConfig {
 
 	result := &SystemPromptPluginConfig{}
 	if err := unmarshalPluginConfig(config, result); err != nil {
+		logging.Errorf("Failed to unmarshal system_prompt config: %v", err)
 		return nil
 	}
 	return result
@@ -666,6 +671,7 @@ func (d *Decision) GetHeaderMutationConfig() *HeaderMutationPluginConfig {
 
 	result := &HeaderMutationPluginConfig{}
 	if err := unmarshalPluginConfig(config, result); err != nil {
+		logging.Errorf("Failed to unmarshal header_mutation config: %v", err)
 		return nil
 	}
 	return result

src/semantic-router/pkg/utils/pii/policy.go

@@ -44,14 +44,17 @@ func NewPolicyChecker(cfg *config.RouterConfig) *PolicyChecker {
 
 // CheckPolicy checks if the detected PII types are allowed for the given decision
 func (pc *PolicyChecker) CheckPolicy(decisionName string, detectedPII []string) (bool, []string, error) {
+	if !pc.IsPIIEnabled(decisionName) {
+		logging.Infof("PII detection is disabled for decision %s, allowing request", decisionName)
+		return true, nil, nil
+	}
+
 	decision := pc.Config.GetDecisionByName(decisionName)
 	if decision == nil {
 		logging.Infof("Decision %s not found, allowing request", decisionName)
 		return true, nil, nil
 	}
 
-	// Get PII policy for this decision
-	// GetDecisionPIIPolicy returns a default policy (AllowByDefault: true) if no PII config exists
 	policy := decision.GetDecisionPIIPolicy()
 	var deniedPII []string