diff --git a/types/src/front/api_handlers/public/assistant.ts b/types/src/front/api_handlers/public/assistant.ts
index e21f1cdf1dd3..2b6ff4f0ef56 100644
--- a/types/src/front/api_handlers/public/assistant.ts
+++ b/types/src/front/api_handlers/public/assistant.ts
@@ -1,17 +1,21 @@
 import * as t from "io-ts";
 
-export const PublicPostMessagesRequestBodySchema = t.type({
-  content: t.string,
-  mentions: t.array(t.type({ configurationId: t.string })),
-  context: t.type({
-    timezone: t.string,
-    username: t.string,
-    fullName: t.union([t.string, t.null]),
-    email: t.union([t.string, t.null]),
-    profilePictureUrl: t.union([t.string, t.null]),
+export const PublicPostMessagesRequestBodySchema = t.intersection([
+  t.type({
+    content: t.string,
+    mentions: t.array(t.type({ configurationId: t.string })),
+    context: t.type({
+      timezone: t.string,
+      username: t.string,
+      fullName: t.union([t.string, t.null]),
+      email: t.union([t.string, t.null]),
+      profilePictureUrl: t.union([t.string, t.null]),
+    }),
   }),
-  isSync: t.union([t.boolean, t.undefined]),
-});
+  t.partial({
+    isSync: t.boolean,
+  }),
+]);
 
 export const PublicPostContentFragmentRequestBodySchema = t.type({
   title: t.string,
@@ -32,18 +36,20 @@ export const PublicPostContentFragmentRequestBodySchema = t.type({
   ]),
 });
 
-export const PublicPostConversationsRequestBodySchema = t.type({
-  title: t.union([t.string, t.null]),
-  visibility: t.union([
-    t.literal("unlisted"),
-    t.literal("workspace"),
-    t.literal("deleted"),
-    t.literal("test"),
-  ]),
-  message: t.union([PublicPostMessagesRequestBodySchema, t.undefined]),
-  contentFragment: t.union([
-    PublicPostContentFragmentRequestBodySchema,
-    t.undefined,
-  ]),
-  isSync: t.union([t.boolean, t.undefined]),
-});
+export const PublicPostConversationsRequestBodySchema = t.intersection([
+  t.type({
+    title: t.union([t.string, t.null]),
+    visibility: t.union([
+      t.literal("unlisted"),
+      t.literal("workspace"),
+      t.literal("deleted"),
+      t.literal("test"),
+    ]),
+    message: t.union([PublicPostMessagesRequestBodySchema, t.undefined]),
+    contentFragment: t.union([
+      PublicPostContentFragmentRequestBodySchema,
+      t.undefined,
+    ]),
+  }),
+  t.partial({ isSync: t.union([t.boolean, t.undefined]) }),
+]);