diff --git a/packages/extension/src/kernel-integration/handlers/send-vat-command.ts b/packages/extension/src/kernel-integration/handlers/send-vat-command.ts
index 3b45a64fd..2efd68479 100644
--- a/packages/extension/src/kernel-integration/handlers/send-vat-command.ts
+++ b/packages/extension/src/kernel-integration/handlers/send-vat-command.ts
@@ -1,7 +1,7 @@
 import { object } from '@metamask/superstruct';
 import { UnsafeJsonStruct } from '@metamask/utils';
 import type { Json } from '@metamask/utils';
-import { isKernelCommand, VatIdStruct } from '@ocap/kernel';
+import { isVatCommandPayloadUI, VatIdStruct } from '@ocap/kernel';
 import type { Kernel, VatId } from '@ocap/kernel';
 import type { MethodSpec, Handler } from '@ocap/rpc-methods';
 
@@ -29,7 +29,7 @@ export const sendVatCommandHandler: Handler<
   ...sendVatCommandSpec,
   hooks: { kernel: true },
   implementation: async ({ kernel }, params): Promise<{ result: Json }> => {
-    if (!isKernelCommand(params.payload)) {
+    if (!isVatCommandPayloadUI(params.payload)) {
       throw new Error('Invalid command payload');
     }
 
diff --git a/packages/extension/test/e2e/vat-manager.test.ts b/packages/extension/test/e2e/vat-manager.test.ts
index 69a916027..fda2e2373 100644
--- a/packages/extension/test/e2e/vat-manager.test.ts
+++ b/packages/extension/test/e2e/vat-manager.test.ts
@@ -187,6 +187,15 @@ test.describe('Vat Manager', () => {
     await popupPage.click('button:text("Send")');
     await expect(messageOutput).toContainText('"method": "ping",');
     await expect(messageOutput).toContainText('{"result":"pong"}');
+    // Test deliver command
+    await clearLogsButton.click();
+    await input.fill(
+      `{ "id": "v1", "payload": { "method": "deliver", "params": ["bringOutYourDead"] } }`,
+    );
+    await popupPage.click('button:text("Send")');
+    await expect(messageOutput).toContainText('"method": "deliver",');
+    await expect(messageOutput).toContainText('"bringOutYourDead"');
+    await expect(messageOutput).toContainText('"result":null}');
   });
 
   test('should reload kernel state and load default vats', async () => {
diff --git a/packages/kernel/src/index.test.ts b/packages/kernel/src/index.test.ts
index 0feabd913..bc02a6c18 100644
--- a/packages/kernel/src/index.test.ts
+++ b/packages/kernel/src/index.test.ts
@@ -18,6 +18,7 @@ describe('index', () => {
       'isKernelCommand',
       'isKernelCommandReply',
       'isVatCommand',
+      'isVatCommandPayloadUI',
       'isVatCommandReply',
       'isVatConfig',
       'isVatId',
diff --git a/packages/kernel/src/messages/index.ts b/packages/kernel/src/messages/index.ts
index 56ab8d687..fb2313973 100644
--- a/packages/kernel/src/messages/index.ts
+++ b/packages/kernel/src/messages/index.ts
@@ -10,7 +10,12 @@ export type { KernelCommand, KernelCommandReply } from './kernel.ts';
 
 // Vat commands.
 
-export { VatCommandMethod, isVatCommand, isVatCommandReply } from './vat.ts';
+export {
+  VatCommandMethod,
+  isVatCommand,
+  isVatCommandReply,
+  isVatCommandPayloadUI,
+} from './vat.ts';
 export type {
   VatCommand,
   VatCommandReply,
diff --git a/packages/kernel/src/messages/vat.ts b/packages/kernel/src/messages/vat.ts
index 1a54945ef..36db3f48c 100644
--- a/packages/kernel/src/messages/vat.ts
+++ b/packages/kernel/src/messages/vat.ts
@@ -294,3 +294,12 @@ export type VatReplyParams<Method extends keyof typeof VatReplyStructs> = Infer<
 export type VatCommandReturnType = {
   [Method in keyof typeof VatReplyStructs]: VatReplyParams<Method>;
 };
+
+const VatCommandPayloadUIStruct = union([
+  VatMethodStructs.ping,
+  VatMethodStructs.deliver,
+]);
+export type VatCommandPayloadUI = Infer<typeof VatCommandPayloadUIStruct>;
+export const isVatCommandPayloadUI = (
+  value: unknown,
+): value is VatCommandPayloadUI => is(value, VatCommandPayloadUIStruct);
diff --git a/vitest.config.ts b/vitest.config.ts
index 578d57855..78cea2223 100644
--- a/vitest.config.ts
+++ b/vitest.config.ts
@@ -88,10 +88,10 @@ export default defineConfig({
           lines: 80.33,
         },
         'packages/kernel/**': {
-          statements: 86.41,
-          functions: 92.76,
+          statements: 86.44,
+          functions: 92.79,
           branches: 71.18,
-          lines: 86.38,
+          lines: 86.41,
         },
         'packages/nodejs/**': {
           statements: 72.91,