feat(gl): add standalone ledger authority mode

domain/ledger/authority.go

@@ -0,0 +1,36 @@
+package ledger
+
+import (
+	"errors"
+	"time"
+)
+
+type OperatingMode string
+
+const (
+	ModeNormal                OperatingMode = "NORMAL"
+	ModeGLOnly                OperatingMode = "GL_ONLY"
+	InternalExecutionMetadata               = "gl_execution"
+)
+
+var (
+	ErrModeConflict       = errors.New("operating mode revision changed")
+	ErrModeRequired       = errors.New("operation is not permitted in the current ledger mode")
+	ErrInsufficientFunds  = errors.New("insufficient ledger funds")
+	ErrSettlementInFlight = errors.New("settlement is in flight; drain the worker before switching")
+	ErrConcurrentPosting  = errors.New("concurrent posting conflicted; retry with the same idempotency key")
+)
+
+type OperatingState struct {
+	Mode      OperatingMode
+	Revision  int64
+	ActorID   string
+	Reason    string
+	ChangedAt time.Time
+}
+
+type UserAssetBalance struct {
+	AssetID   int64
+	Available Amount
+	Frozen    Amount
+}