fix: correct A2UI MIME type constant in Lit clients (#418)

- Rename A2AUI_MIME_TYPE to A2UI_MIME_TYPE for consistency with server-side
- Fix value from 'application/json+a2aui' to 'application/json+a2ui'
- Affects shell/client.ts, shell/middleware/a2a.ts, contact/middleware/a2a.ts

Author: doitundoit

samples/client/lit/contact/middleware/a2a.ts

@@ -25,7 +25,7 @@ import {
 } from "@a2a-js/sdk";
 import { v4 as uuidv4 } from "uuid";
 
-const A2AUI_MIME_TYPE = "application/json+a2aui";
+const A2UI_MIME_TYPE = "application/json+a2ui";
 
 const fetchWithCustomHeader: typeof fetch = async (url, init) => {
   const headers = new Headers(init?.headers);
@@ -92,7 +92,7 @@ export const plugin = (): Plugin => {
                       {
                         kind: "data",
                         data: clientEvent,
-                        metadata: { 'mimeType': A2AUI_MIME_TYPE },
+                        metadata: { 'mimeType': A2UI_MIME_TYPE },
                       } as Part,
                     ],
                     kind: "message",

samples/client/lit/shell/client.ts

@@ -18,7 +18,7 @@ import { Part, SendMessageSuccessResponse, Task } from "@a2a-js/sdk";
 import { A2AClient } from "@a2a-js/sdk/client";
 import { v0_8 } from "@a2ui/lit";
 
-const A2AUI_MIME_TYPE = "application/json+a2aui";
+const A2UI_MIME_TYPE = "application/json+a2ui";
 
 export class A2UIClient {
   #serverUrl: string;
@@ -67,7 +67,7 @@ export class A2UIClient {
           parts = [{
             kind: "data",
             data: parsed as unknown as Record<string, unknown>,
-            mimeType: A2AUI_MIME_TYPE,
+            mimeType: A2UI_MIME_TYPE,
           } as Part];
         } else {
           parts = [{ kind: "text", text: message }];
@@ -79,7 +79,7 @@ export class A2UIClient {
       parts = [{
         kind: "data",
         data: message as unknown as Record<string, unknown>,
-        mimeType: A2AUI_MIME_TYPE,
+        mimeType: A2UI_MIME_TYPE,
       } as Part];
     }
 

samples/client/lit/shell/middleware/a2a.ts

@@ -25,7 +25,7 @@ import {
 } from "@a2a-js/sdk";
 import { v4 as uuidv4 } from "uuid";
 
-const A2AUI_MIME_TYPE = "application/json+a2aui";
+const A2UI_MIME_TYPE = "application/json+a2ui";
 
 const fetchWithCustomHeader: typeof fetch = async (url, init) => {
   const headers = new Headers(init?.headers);
@@ -92,7 +92,7 @@ export const plugin = (): Plugin => {
                       {
                         kind: "data",
                         data: clientEvent,
-                        metadata: { 'mimeType': A2AUI_MIME_TYPE }, 
+                        metadata: { 'mimeType': A2UI_MIME_TYPE },
                       } as Part,
                     ],
                     kind: "message",