@@ -0,0 +1,163 @@
+package controlledsession
+
+import "fmt"
+
+type TerminationCauseV1 string
+
+const (
+	CauseControllerCompleteV1     TerminationCauseV1 = "controller-complete"
+	CauseControllerTerminateV1    TerminationCauseV1 = "controller-terminate"
+	CauseApplicationExitV1        TerminationCauseV1 = "application-exit"
+	CauseHostCancelV1             TerminationCauseV1 = "host-cancel"
+	CauseControllerLostV1         TerminationCauseV1 = "controller-lost"
+	CauseRuntimeObservationLostV1 TerminationCauseV1 = "runtime-observation-lost"
+	CauseStartupFailureV1         TerminationCauseV1 = "startup-failure"
+)
+
+type ProcessStatusKindV1 string
+
+const (
+	ProcessStatusUnknownV1     ProcessStatusKindV1 = "unknown"
+	ProcessStatusExitedV1      ProcessStatusKindV1 = "exited"
+	ProcessStatusTerminatedV1  ProcessStatusKindV1 = "terminated"
+	ProcessStatusUnavailableV1 ProcessStatusKindV1 = "unavailable"
+)
+
+type ProcessStatusV1 struct {
+	Kind   ProcessStatusKindV1 `json:"kind"`
+	Code   *int                `json:"code,omitempty"`
+	Reason string              `json:"reason,omitempty"`
+}
+
+type ControllerStatusKindV1 string
+
+const (
+	ControllerStatusUnknownV1             ControllerStatusKindV1 = "unknown"
+	ControllerStatusActiveV1              ControllerStatusKindV1 = "active"
+	ControllerStatusCompletedV1           ControllerStatusKindV1 = "completed"
+	ControllerStatusLostV1                ControllerStatusKindV1 = "lost"
+	ControllerStatusFinalizationTimeoutV1 ControllerStatusKindV1 = "finalization-timeout"
+	ControllerStatusStoppedV1             ControllerStatusKindV1 = "stopped"
+	ControllerStatusStartupFailedV1       ControllerStatusKindV1 = "startup-failed"
+)
+
+type ControllerStatusV1 struct {
+	Kind   ControllerStatusKindV1 `json:"kind"`
+	Reason string                 `json:"reason,omitempty"`
+}
+
+type CleanupStatusKindV1 string
+
+const (
+	CleanupStatusSucceededV1 CleanupStatusKindV1 = "succeeded"
+	CleanupStatusFailedV1    CleanupStatusKindV1 = "failed"
+)
+
+type CleanupStatusV1 struct {
+	Kind    CleanupStatusKindV1 `json:"kind"`
+	Message string              `json:"message,omitempty"`
+}
+
+type RecoveryActionV1 string
+
+const (
+	RecoveryNoneV1                   RecoveryActionV1 = "none"
+	RecoveryRetryCleanupV1           RecoveryActionV1 = "retry-cleanup"
+	RecoveryReconcileNextOperationV1 RecoveryActionV1 = "reconcile-next-operation"
+)
+
+type ResultV1 struct {
+	Cause             TerminationCauseV1 `json:"cause"`
+	ApplicationStatus ProcessStatusV1    `json:"application_status"`
+	ControllerStatus  ControllerStatusV1 `json:"controller_status"`
+	CleanupStatus     CleanupStatusV1    `json:"cleanup_status"`
+	RecoveryAction    RecoveryActionV1   `json:"recovery_action"`
+}
+
+func ValidateResultV1(result ResultV1) error {
+	if !validTerminationCauseV1(result.Cause) {
+		return fmt.Errorf("controlled-session termination cause %q is invalid", result.Cause)
+	}
+	if err := validateProcessStatusV1(result.ApplicationStatus, true); err != nil {
+		return err
+	}
+	if err := validateTerminalControllerStatusV1(result.ControllerStatus); err != nil {
+		return err
+	}
+	return validateCleanupResultV1(result.CleanupStatus, result.RecoveryAction)
+}
+
+func validateProcessStatusV1(status ProcessStatusV1, allowUnknown bool) error {
+	switch status.Kind {
+	case ProcessStatusUnknownV1:
+		if !allowUnknown || status.Code != nil || status.Reason != "" {
+			return fmt.Errorf("unknown application status must have no code or reason")
+		}
+	case ProcessStatusExitedV1:
+		if status.Code == nil {
+			return fmt.Errorf("exited application status requires an exit code")
+		}
+	case ProcessStatusTerminatedV1, ProcessStatusUnavailableV1:
+		if status.Code != nil {
+			return fmt.Errorf("application status %q must not contain an exit code", status.Kind)
+		}
+	default:
+		return fmt.Errorf("application status %q is invalid", status.Kind)
+	}
+	return validateOptionalSafeTextV1("application status reason", status.Reason)
+}
+
+func validateTerminalControllerStatusV1(status ControllerStatusV1) error {
+	switch status.Kind {
+	case ControllerStatusCompletedV1, ControllerStatusLostV1, ControllerStatusFinalizationTimeoutV1, ControllerStatusStoppedV1, ControllerStatusStartupFailedV1:
+	default:
+		return fmt.Errorf("terminal controller status %q is invalid", status.Kind)
+	}
+	return validateOptionalSafeTextV1("controller status reason", status.Reason)
+}
+
+func validateCleanupResultV1(status CleanupStatusV1, recovery RecoveryActionV1) error {
+	switch status.Kind {
+	case CleanupStatusSucceededV1:
+		if status.Message != "" {
+			return fmt.Errorf("successful cleanup status must not contain an error message")
+		}
+		if recovery != RecoveryNoneV1 {
+			return fmt.Errorf("successful cleanup must not require recovery")
+		}
+	case CleanupStatusFailedV1:
+		if err := validateRequiredSafeTextV1("cleanup failure message", status.Message); err != nil {
+			return err
+		}
+		if recovery != RecoveryRetryCleanupV1 && recovery != RecoveryReconcileNextOperationV1 {
+			return fmt.Errorf("failed cleanup requires a recovery action")
+		}
+	default:
+		return fmt.Errorf("cleanup status %q is invalid", status.Kind)
+	}
+	return nil
+}
+
+func validateOptionalSafeTextV1(field string, value string) error {
+	if value == "" {
+		return nil
+	}
+	return validateSafeTextV1(field, value)
+}
+
+func validateRequiredSafeTextV1(field string, value string) error {
+	if value == "" {
+		return fmt.Errorf("controlled-session %s is required", field)
+	}
+	return validateSafeTextV1(field, value)
+}
+
+func validTerminationCauseV1(cause TerminationCauseV1) bool {
+	switch cause {
+	case CauseControllerCompleteV1, CauseControllerTerminateV1, CauseApplicationExitV1, CauseHostCancelV1,
+		CauseControllerLostV1, CauseRuntimeObservationLostV1, CauseStartupFailureV1:
+		return true
+	default:
+		return false
+	}
+}