diff --git a/core/shared/src/main/scala/works/iterative/core/UserHandle.scala b/core/shared/src/main/scala/works/iterative/core/UserHandle.scala
index 82bfcb9..85124f0 100644
--- a/core/shared/src/main/scala/works/iterative/core/UserHandle.scala
+++ b/core/shared/src/main/scala/works/iterative/core/UserHandle.scala
@@ -1,4 +1,5 @@
 package works.iterative.core
+import auth.UserId
 
 /** A simple object to hold unique user identification together with "humane"
   * identification Usually we need to display the user's name in the UI, which

diff --git a/core/shared/src/main/scala/works/iterative/core/UserHandle.scala b/core/shared/src/main/scala/works/iterative/core/UserHandle.scala
index 82bfcb9..85124f0 100644
--- a/core/shared/src/main/scala/works/iterative/core/UserHandle.scala
+++ b/core/shared/src/main/scala/works/iterative/core/UserHandle.scala
@@ -1,4 +1,5 @@
 package works.iterative.core
+import auth.UserId
 
 /** A simple object to hold unique user identification together with "humane"
   * identification Usually we need to display the user's name in the UI, which
diff --git a/core/shared/src/main/scala/works/iterative/core/UserId.scala b/core/shared/src/main/scala/works/iterative/core/UserId.scala
deleted file mode 100644
index e82c89f..0000000
--- a/core/shared/src/main/scala/works/iterative/core/UserId.scala
+++ /dev/null
@@ -1,13 +0,0 @@
-package works.iterative.core
-
-// Unique identifier of the user
-opaque type UserId = String
-
-object UserId:
-  def apply(value: String): Validated[UserId] =
-    // Validate that the value is not empty
-    Validated.nonEmptyString("user.id")(value)
-
-  def unsafe(value: String): UserId = value
-
-  extension (u: UserId) def value: String = u

diff --git a/core/shared/src/main/scala/works/iterative/core/UserHandle.scala b/core/shared/src/main/scala/works/iterative/core/UserHandle.scala
index 82bfcb9..85124f0 100644
--- a/core/shared/src/main/scala/works/iterative/core/UserHandle.scala
+++ b/core/shared/src/main/scala/works/iterative/core/UserHandle.scala
@@ -1,4 +1,5 @@
 package works.iterative.core
+import auth.UserId
 
 /** A simple object to hold unique user identification together with "humane"
   * identification Usually we need to display the user's name in the UI, which
diff --git a/core/shared/src/main/scala/works/iterative/core/UserId.scala b/core/shared/src/main/scala/works/iterative/core/UserId.scala
deleted file mode 100644
index e82c89f..0000000
--- a/core/shared/src/main/scala/works/iterative/core/UserId.scala
+++ /dev/null
@@ -1,13 +0,0 @@
-package works.iterative.core
-
-// Unique identifier of the user
-opaque type UserId = String
-
-object UserId:
-  def apply(value: String): Validated[UserId] =
-    // Validate that the value is not empty
-    Validated.nonEmptyString("user.id")(value)
-
-  def unsafe(value: String): UserId = value
-
-  extension (u: UserId) def value: String = u
diff --git a/core/shared/src/main/scala/works/iterative/core/auth/PermissionService.scala b/core/shared/src/main/scala/works/iterative/core/auth/PermissionService.scala
index 6a5c831..6edb8e4 100644
--- a/core/shared/src/main/scala/works/iterative/core/auth/PermissionService.scala
+++ b/core/shared/src/main/scala/works/iterative/core/auth/PermissionService.scala
@@ -13,7 +13,7 @@
   def apply(namespace: String, id: String): PermissionTarget =
     require(
       namespace.trim.nonEmpty && id.trim.nonEmpty,
-      "Both namespece and id must be defined"
+      "Both namespace and id must be defined"
     )
     require(
       namespace.indexOf(':') == -1 && id.indexOf(':') == -1,

diff --git a/core/shared/src/main/scala/works/iterative/core/UserHandle.scala b/core/shared/src/main/scala/works/iterative/core/UserHandle.scala
index 82bfcb9..85124f0 100644
--- a/core/shared/src/main/scala/works/iterative/core/UserHandle.scala
+++ b/core/shared/src/main/scala/works/iterative/core/UserHandle.scala
@@ -1,4 +1,5 @@
 package works.iterative.core
+import auth.UserId
 
 /** A simple object to hold unique user identification together with "humane"
   * identification Usually we need to display the user's name in the UI, which
diff --git a/core/shared/src/main/scala/works/iterative/core/UserId.scala b/core/shared/src/main/scala/works/iterative/core/UserId.scala
deleted file mode 100644
index e82c89f..0000000
--- a/core/shared/src/main/scala/works/iterative/core/UserId.scala
+++ /dev/null
@@ -1,13 +0,0 @@
-package works.iterative.core
-
-// Unique identifier of the user
-opaque type UserId = String
-
-object UserId:
-  def apply(value: String): Validated[UserId] =
-    // Validate that the value is not empty
-    Validated.nonEmptyString("user.id")(value)
-
-  def unsafe(value: String): UserId = value
-
-  extension (u: UserId) def value: String = u
diff --git a/core/shared/src/main/scala/works/iterative/core/auth/PermissionService.scala b/core/shared/src/main/scala/works/iterative/core/auth/PermissionService.scala
index 6a5c831..6edb8e4 100644
--- a/core/shared/src/main/scala/works/iterative/core/auth/PermissionService.scala
+++ b/core/shared/src/main/scala/works/iterative/core/auth/PermissionService.scala
@@ -13,7 +13,7 @@
   def apply(namespace: String, id: String): PermissionTarget =
     require(
       namespace.trim.nonEmpty && id.trim.nonEmpty,
-      "Both namespece and id must be defined"
+      "Both namespace and id must be defined"
     )
     require(
       namespace.indexOf(':') == -1 && id.indexOf(':') == -1,
diff --git a/core/shared/src/main/scala/works/iterative/core/auth/UserId.scala b/core/shared/src/main/scala/works/iterative/core/auth/UserId.scala
index ceac729..2a2c200 100644
--- a/core/shared/src/main/scala/works/iterative/core/auth/UserId.scala
+++ b/core/shared/src/main/scala/works/iterative/core/auth/UserId.scala
@@ -1,9 +1,15 @@
 package works.iterative.core.auth
 
-/** Opaque type to distinguish user identifiers */
+import works.iterative.core.Validated
+
+// Unique identifier of the user
 opaque type UserId = String
 
 object UserId:
-  def apply(value: String): UserId = value
+  def apply(value: String): Validated[UserId] =
+    // Validate that the value is not empty
+    Validated.nonEmptyString("user.id")(value)
 
-  extension (userId: UserId) def value: String = userId
+  def unsafe(value: String): UserId = value
+
+  extension (u: UserId) def value: String = u