move IDGenerator interface to service package

service/ulid.go

@@ -0,0 +1,21 @@
+package service
+
+import "github.com/oklog/ulid/v2"
+
+// IDGenerator produces unique identifiers for entities.
+type IDGenerator interface {
+	// NewID generates a new unique identifier for entities.
+	NewID() string
+}
+
+// defaultIDGenerator generates ULIDs using crypto/rand entropy.
+type defaultIDGenerator struct{}
+
+func (defaultIDGenerator) NewID() string {
+	return ulid.Make().String()
+}
+
+// DefaultIDGenerator returns the standard ULID-based generator.
+func DefaultIDGenerator() IDGenerator {
+	return defaultIDGenerator{}
+}