diff --git a/internal/pkg/pkg.go b/internal/pkg/pkg.go
index ab1f3e0..f5bd9d3 100644
--- a/internal/pkg/pkg.go
+++ b/internal/pkg/pkg.go
@@ -191,6 +191,10 @@ const (
 	KindExecNet
 	// KindFile is the kind of [Artifact] returned by [NewFile].
 	KindFile
+
+	// KindCustomOffset is the first [Kind] value reserved for implementations
+	// not from this package.
+	KindCustomOffset = 1 << 31
 )
 
 // Ident returns a deterministic identifier for the supplied params and