shutdown

const (
	// ExitOK indicates successful termination.
	//
	// Use when:
	//   - the application completed its work successfully
	//   - a server shut down gracefully after receiving SIGTERM
	//   - a CLI command or seed finished without errors
	//
	// MUST be used for normal, expected shutdown.
	ExitOK = 0

	// ExitGeneralError indicates an unspecified failure.
	//
	// Use when:
	//   - an error occurred but does not fit a more specific category
	//   - acting as a fallback error code
	//
	// Avoid using this when a more precise exit code exists.
	ExitGeneralError = 1

	// ExitUsage indicates incorrect command usage.
	//
	// Use when:
	//   - CLI arguments are invalid
	//   - required flags are missing
	//   - incompatible flags are provided
	//
	// Typical for CLI tools and admin commands.
	ExitUsage = 64

	// ExitDataError indicates invalid input data.
	//
	// Use when:
	//   - input data is malformed
	//   - JSON / YAML / CSV parsing fails due to invalid content
	//   - semantic validation fails
	ExitDataError = 65

	// ExitNoInput indicates a missing required input.
	//
	// Use when:
	//   - a required file does not exist
	//   - stdin or expected input source is unavailable
	ExitNoInput = 66

	// ExitUnavailable indicates that a required external service is unavailable.
	//
	// Use when:
	//   - database cannot be reached
	//   - Redis / Kafka / external API is down
	//   - network dependency is unreachable at startup
	//
	// This usually triggers restart in orchestration systems.
	ExitUnavailable = 69

	// ExitSoftware indicates an internal software error.
	//
	// Use when:
	//   - an invariant is violated
	//   - unexpected state is reached
	//   - a bug is detected but panic is not used
	ExitSoftware = 70

	// ExitOSError indicates an operating system error.
	//
	// Use when:
	//   - syscall failures occur
	//   - OS-level resources cannot be accessed
	ExitOSError = 71

	// ExitIOError indicates a low-level I/O failure.
	//
	// Use when:
	//   - disk read/write fails
	//   - socket I/O fails unexpectedly
	ExitIOError = 74

	// ExitTempFail indicates a temporary failure.
	//
	// Use when:
	//   - the operation can be retried
	//   - transient network issues occur
	//   - rate limits are hit
	//
	// Supervisors may retry automatically.
	ExitTempFail = 75

	// ExitNoPermission indicates insufficient permissions.
	//
	// Use when:
	//   - access to secrets is denied
	//   - filesystem permissions are insufficient
	//   - security constraints prevent startup
	ExitNoPermission = 77

	// ExitConfigError indicates an invalid configuration.
	//
	// Use when:
	//   - required environment variables are missing
	//   - configuration files are invalid or malformed
	//   - configuration values fail validation
	//
	// This is one of the most important exit codes for production systems.
	ExitConfigError = 78

	// ExitPanic indicates the application terminated due to a panic.
	//
	// Use when:
	//   - a panic was recovered in main()
	//   - an unrecoverable programming error occurred
	//
	// Panics SHOULD be treated differently from normal errors.
	ExitPanic = 10

	// ExitShutdownError indicates failure during graceful shutdown.
	//
	// Use when:
	//   - shutdown handlers exceed timeout
	//   - resources fail to close cleanly
	//
	// The application attempted to shut down gracefully but failed.
	ExitShutdownError = 20

	// ExitSignalBase is the base exit code for Unix signals.
	//
	// Actual exit code is calculated as:
	//   128 + signal number
	//
	// Examples:
	//   SIGINT  (2)  → 130
	//   SIGTERM (15) → 143
	//   SIGKILL (9)  → 137
	//
	// This value MUST NOT be returned manually.
	ExitSignalBase = 128
)