fix(ers): coerce attempted_strategies []string to []interface{} for structpb

service/entityresolution/multi-strategy/service.go

@@ -116,7 +116,17 @@ func (s *Service) ResolveEntity(ctx context.Context, entityID string, claimsMap
 		result.Metadata["strategy_provider"] = strategy.Provider
 		result.Metadata["entity_type"] = strategy.EntityType
 		result.Metadata["failure_strategy"] = failureStrategy
-		result.Metadata["attempted_strategies"] = attemptedStrategies
+		// Coerce []string -> []interface{} so structpb.NewValue (called by
+		// the v2 ResolveEntities handler when it serializes metadata into
+		// EntityRepresentation.AdditionalProps) can encode it. structpb's
+		// NewValue accepts string|float64|bool|nil|map|[]interface{} only -
+		// a raw []string trips "proto: invalid type: []string" and the
+		// resolved entity is silently dropped via `continue` in the loop.
+		attemptedAny := make([]interface{}, len(attemptedStrategies))
+		for i, strat := range attemptedStrategies {
+			attemptedAny[i] = strat
+		}
+		result.Metadata["attempted_strategies"] = attemptedAny
 
 		return result, nil
 	}

service/entityresolution/multi-strategy/service_test.go

@@ -296,8 +296,12 @@ func TestMultiStrategyService_FailureStrategyContinue(t *testing.T) {
 		t.Errorf("Expected entity_type '%s', got '%v'", types.EntityTypeSubject, result.Metadata["entity_type"])
 	}
 
-	// Verify attempted strategies metadata
-	attemptedStrategies, ok := result.Metadata["attempted_strategies"].([]string)
+	// Verify attempted strategies metadata. Stored as []interface{} (rather
+	// than []string) so the value can flow through structpb.NewValue when
+	// the v2 ResolveEntities handler serializes result.Metadata into
+	// EntityRepresentation.AdditionalProps; structpb does not accept
+	// []string.
+	attemptedStrategies, ok := result.Metadata["attempted_strategies"].([]interface{})
 	if !ok || len(attemptedStrategies) != 2 {
 		t.Errorf("Expected attempted_strategies to contain 2 strategies, got %v", result.Metadata["attempted_strategies"])
 	}