From e49b9ffb4dc035809ddfc02fb05945bb41f611c7 Mon Sep 17 00:00:00 2001
From: Charly Chevalier <charly.chevalier@consensys.net>
Date: Tue, 30 Jun 2026 14:16:58 +0200
Subject: [PATCH] feat: add exactOptional support in type struct

---
 src/structs/types.ts                          |  6 ++++++
 test/typings/exactOptional.ts                 | 15 +++++++++++++
 .../type/invalid-exact-optional-undefined.ts  | 21 +++++++++++++++++++
 .../type/valid-exact-optional-absent.ts       | 12 +++++++++++
 .../type/valid-exact-optional-present.ts      | 13 ++++++++++++
 5 files changed, 67 insertions(+)
 create mode 100644 test/validation/type/invalid-exact-optional-undefined.ts
 create mode 100644 test/validation/type/valid-exact-optional-absent.ts
 create mode 100644 test/validation/type/valid-exact-optional-present.ts

diff --git a/src/structs/types.ts b/src/structs/types.ts
index b40a1bd4..26c9e01e 100644
--- a/src/structs/types.ts
+++ b/src/structs/types.ts
@@ -684,6 +684,12 @@ export function type<Schema extends ObjectSchema>(
     *entries(value) {
       if (isObject(value)) {
         for (const k of keys) {
+          if (
+            ExactOptionalStruct.isExactOptional(schema[k]) &&
+            !Object.prototype.hasOwnProperty.call(value, k)
+          ) {
+            continue;
+          }
           yield [k, value[k], schema[k] as Struct<any>];
         }
       }
diff --git a/test/typings/exactOptional.ts b/test/typings/exactOptional.ts
index 2daf616b..66941818 100644
--- a/test/typings/exactOptional.ts
+++ b/test/typings/exactOptional.ts
@@ -4,6 +4,7 @@ import {
   string,
   number,
   object,
+  type,
   enums,
   never,
   record,
@@ -60,3 +61,17 @@ test<{
   );
   return value;
 });
+
+test<{
+  a?: number;
+  b: string;
+}>((value) => {
+  assert(
+    value,
+    type({
+      a: exactOptional(number()),
+      b: string(),
+    }),
+  );
+  return value;
+});
diff --git a/test/validation/type/invalid-exact-optional-undefined.ts b/test/validation/type/invalid-exact-optional-undefined.ts
new file mode 100644
index 00000000..dc2cbb99
--- /dev/null
+++ b/test/validation/type/invalid-exact-optional-undefined.ts
@@ -0,0 +1,21 @@
+import { type, exactOptional, string, number } from '../../../src';
+
+export const Struct = type({
+  name: string(),
+  age: exactOptional(number()),
+});
+
+export const data = {
+  name: 'john',
+  age: undefined,
+};
+
+export const failures = [
+  {
+    value: undefined,
+    type: 'number',
+    refinement: undefined,
+    path: ['age'],
+    branch: [data, data.age],
+  },
+];
diff --git a/test/validation/type/valid-exact-optional-absent.ts b/test/validation/type/valid-exact-optional-absent.ts
new file mode 100644
index 00000000..2e4f6e88
--- /dev/null
+++ b/test/validation/type/valid-exact-optional-absent.ts
@@ -0,0 +1,12 @@
+import { type, exactOptional, string, number } from '../../../src';
+
+export const Struct = type({
+  name: string(),
+  age: exactOptional(number()),
+});
+
+export const data = {
+  name: 'john',
+};
+
+export const output = data;
diff --git a/test/validation/type/valid-exact-optional-present.ts b/test/validation/type/valid-exact-optional-present.ts
new file mode 100644
index 00000000..34407b46
--- /dev/null
+++ b/test/validation/type/valid-exact-optional-present.ts
@@ -0,0 +1,13 @@
+import { type, exactOptional, string, number } from '../../../src';
+
+export const Struct = type({
+  name: string(),
+  age: exactOptional(number()),
+});
+
+export const data = {
+  name: 'john',
+  age: 42,
+};
+
+export const output = data;