// ******************************************************************************************
// This protocol is UNSTABLE in the sense of being subject to change.
// ******************************************************************************************

syntax = "proto3";

package kurrent.rpc;

option csharp_namespace = "Kurrent.Rpc";

import "google/protobuf/descriptor.proto";
import "google/rpc/code.proto";

// ErrorMetadata provides actionable information for error enum values to enable automated
// code generation, documentation, and consistent error handling across the Kurrent platform.
//
// It was modeled to support a single details type per error code to simplify code generation and
// validation. If multiple detail types are needed for a single error code, consider defining
// separate error codes for each detail type. Or, use a union type (oneof) in the detail message
// to encapsulate multiple detail variants within a single detail message.
//
// More however DebugInfo and RetryInfo can and should be added to any error regardless of
// this setting, when applicable.
//
// This annotation is applied to enum values using the google.protobuf.EnumValueOptions
// extension mechanism. It enables:
// - Automatic gRPC status code mapping
// - Code generation for error handling utilities
// - Documentation generation
// - Type-safe error detail validation
//
// Usage Example:
//   enum StreamErrorCode {
//     REVISION_CONFLICT = 5 [(kurrent.rpc.error) = {
//       status_code: FAILED_PRECONDITION,
//       has_details: true
//     }];
//   }
//
// See individual field documentation for conventions and defaults.
message ErrorMetadata {
  // Maps the error to a standard gRPC status code for transport-level compatibility.
  // This field is REQUIRED for every error annotation.
  //
  // Use standard gRPC status codes from `google.rpc.code`.
  //
  // Code generators use this to:
  // - Map errors to gRPC status codes automatically
  // - Generate HTTP status code mappings
  // - Create transport-agnostic error handling
  google.rpc.Code status_code = 1;

  // Indicates whether this error supports rich, typed detail messages.
  // Defaults to false (simple message string only).
  // The message type name must be derived from the enum name by convention.
  // Mask: {EnumValue}ErrorDetails, {EnumValue}Error, {EnumValue}
  //
  // Examples:
  //   ACCESS_DENIED    -> "AccessDeniedErrorDetails", "AccessDeniedError" or "AccessDenied"
  //   SERVER_NOT_READY -> "ServerNotReadyErrorDetails", "ServerNotReadyError" or "ServerNotReady"
  //
  // Code generators use the message type name to:
  // - Validate that the detail message matches the expected type
  // - Generate type-safe error handling code
  // - Create accurate documentation
  bool has_details = 2;
}

// Extend EnumValueOptions to include error information for enum values
extend google.protobuf.EnumValueOptions {
  // Provides additional information about error conditions for automated
  // code generation and documentation.
  optional ErrorMetadata error = 2113;
}