Add validator chain config overrides

internal/core/config/validation.go

@@ -85,7 +85,7 @@ func validatePipelineProfiles(profiles map[string]pipeline.PipelineProfile) erro
 				return err
 			}
 			if len(lane.Validators) > 0 {
-				return fmt.Errorf("pipeline %q lane %q validators are not supported by the current raw validation runner", id, laneID)
+				return fmt.Errorf("pipeline %q lane %q validators are not supported at artifact lane level; use extract.validators, merge.validators, or normalize.validators", id, laneID)
 			}
 		}
 	}
@@ -108,6 +108,9 @@ func validateBinding(
 		}
 		return fmt.Errorf("pipeline %q %s retries must be greater than or equal to zero", pipelineID, slot)
 	}
+	if err := validateValidatorOverride(pipelineID, laneID, slot, binding.Validators); err != nil {
+		return err
+	}
 	if len(binding.References) == 0 {
 		return nil
 	}
@@ -120,6 +123,36 @@ func validateBinding(
 	return validateReferenceMapForContext(pipelineID, laneID, slot, binding.References)
 }
 
+func validateValidatorOverride(pipelineID string, laneID string, slot string, override pipeline.ValidatorOverride) error {
+	if !override.Set {
+		return nil
+	}
+	switch slot {
+	case "chunk", "extract", "merge", "normalize":
+	default:
+		return fmt.Errorf("%s validators are not supported", referenceContext(pipelineID, laneID, slot))
+	}
+	for i, validator := range override.Validators {
+		context := fmt.Sprintf("%s validators[%d]", referenceContext(pipelineID, laneID, slot), i)
+		if strings.TrimSpace(validator.Module) == "" {
+			return fmt.Errorf("%s module must not be empty", context)
+		}
+		if len(validator.References) > 0 {
+			return fmt.Errorf("%s references are not supported", context)
+		}
+		if validator.Validators.Set {
+			return fmt.Errorf("%s nested validators are not supported", context)
+		}
+		if validator.Retries != 0 {
+			return fmt.Errorf("%s retries are not supported", context)
+		}
+		if validator.LLMProfile != "" && strings.TrimSpace(validator.LLMProfile) == "" {
+			return fmt.Errorf("%s llm_profile must not be empty when set", context)
+		}
+	}
+	return nil
+}
+
 func validateReferenceMap(pipelineID string, laneID string, references map[string]string) error {
 	return validateReferenceMapForContext(pipelineID, laneID, "", references)
 }