diff --git a/.changeset/fix-sys-user-unique-validation.md b/.changeset/fix-sys-user-unique-validation.md
new file mode 100644
index 0000000000..f7742a7375
--- /dev/null
+++ b/.changeset/fix-sys-user-unique-validation.md
@@ -0,0 +1,13 @@
+---
+"@objectstack/platform-objects": patch
+---
+
+fix(platform-objects): remove invalid `unique` validation rule on sys_user
+
+`sys_user` declared a `validations: [{ type: 'unique', ... }]` rule, but #1485
+removed `'unique'` from the enforceable validation-rule types (uniqueness is an
+index concern, not a validation rule). The stray rule slipped onto `main` as a
+semantic merge conflict and failed schema parse at registration (ZodError:
+invalid discriminator value), breaking Test Core. Email uniqueness is already
+enforced by the unique index (`indexes: [{ fields: ['email'], unique: true }]`),
+so the redundant validation block is removed.
diff --git a/packages/platform-objects/src/identity/sys-user.object.ts b/packages/platform-objects/src/identity/sys-user.object.ts
index 380318876f..7937261d3c 100644
--- a/packages/platform-objects/src/identity/sys-user.object.ts
+++ b/packages/platform-objects/src/identity/sys-user.object.ts
@@ -439,14 +439,8 @@ export const SysUser = ObjectSchema.create({
     mru: true,
   },
 
-  validations: [
-    {
-      name: 'email_unique',
-      type: 'unique',
-      severity: 'error',
-      message: 'Email must be unique',
-      fields: ['email'],
-      caseSensitive: false,
-    },
-  ],
+  // Email uniqueness is enforced by the unique index declared above
+  // (`indexes: [{ fields: ['email'], unique: true }]`). The standalone `unique`
+  // validation rule was removed in #1485 — uniqueness is an index concern, not
+  // an enforceable validation-rule type — so no `validations` block is needed.
 });