diff --git a/src/data/languages/languageData.ts b/src/data/languages/languageData.ts
index b7bbd5e8a2..e1788fdb19 100644
--- a/src/data/languages/languageData.ts
+++ b/src/data/languages/languageData.ts
@@ -44,7 +44,7 @@ export default {
     android: '1.2',
   },
   aiTransport: {
-    javascript: '0.2',
+    javascript: '0.3',
   },
   spaces: {
     javascript: '0.5',
diff --git a/src/pages/docs/ai-transport/api/errors.mdx b/src/pages/docs/ai-transport/api/errors.mdx
index e3597de0d1..a9b8c7ec58 100644
--- a/src/pages/docs/ai-transport/api/errors.mdx
+++ b/src/pages/docs/ai-transport/api/errors.mdx
@@ -63,6 +63,7 @@ Auth and channel errors come from the Ably platform, not AI Transport. The most
 | 40300 | Forbidden. | The token is valid but not authorised for this resource. |
 | 80000 | Channel attach failed. | Check the channel name and capability. |
 | 90000 | Internal channel error. | Retry the operation. If the error persists, contact support. |
+| 93002 | `Can only update/delete/append messages on channels with mutableMessages enabled`. The namespace lacks the `mutableMessages` rule, so AI Transport cannot append stream tokens. This is the most common AI Transport setup failure. | Enable the **Message annotations, updates, deletes, and appends** rule on the namespace. See [Configure the channel rule](/docs/ai-transport/getting-started/channel-rules). |
 
 The full Ably error code list lives at [Ably error codes](/docs/sdks/error-codes).
 
diff --git a/src/pages/docs/ai-transport/frameworks/vercel-ai-sdk-core.mdx b/src/pages/docs/ai-transport/frameworks/vercel-ai-sdk-core.mdx
index 841c2bfad2..f5a7b2303a 100644
--- a/src/pages/docs/ai-transport/frameworks/vercel-ai-sdk-core.mdx
+++ b/src/pages/docs/ai-transport/frameworks/vercel-ai-sdk-core.mdx
@@ -9,6 +9,10 @@ intro: "Vercel AI SDK Core gives you streamText for orchestrating LLMs on the se
 
 Ready to build? See [Get started with Vercel AI SDK](/docs/ai-transport/getting-started/vercel-ai-sdk).
 
+<Aside data-type='important'>
+AI Transport requires the **Message annotations, updates, deletes, and appends** [channel rule](/docs/ai-transport/getting-started/channel-rules) on the namespace your conversations live on. Enable it once per Ably app, or streaming fails with error `93002`.
+</Aside>
+
 ## What Vercel AI SDK Core brings <a id="vercel-brings"/>
 
 | Capability | Description |
diff --git a/src/pages/docs/ai-transport/frameworks/vercel-ai-sdk-ui.mdx b/src/pages/docs/ai-transport/frameworks/vercel-ai-sdk-ui.mdx
index 7571e99ba3..9d06816657 100644
--- a/src/pages/docs/ai-transport/frameworks/vercel-ai-sdk-ui.mdx
+++ b/src/pages/docs/ai-transport/frameworks/vercel-ai-sdk-ui.mdx
@@ -11,6 +11,10 @@ redirect_from:
 
 Ready to build? See [Get started with Vercel AI SDK](/docs/ai-transport/getting-started/vercel-ai-sdk).
 
+<Aside data-type='important'>
+AI Transport requires the **Message annotations, updates, deletes, and appends** [channel rule](/docs/ai-transport/getting-started/channel-rules) on the namespace your conversations live on. Enable it once per Ably app, or streaming fails with error `93002`.
+</Aside>
+
 ## What Vercel AI SDK UI brings <a id="vercel-brings"/>
 
 | Capability | Description |
diff --git a/src/pages/docs/ai-transport/getting-started/authentication.mdx b/src/pages/docs/ai-transport/getting-started/authentication.mdx
index 90493be7de..a07bc29ffa 100644
--- a/src/pages/docs/ai-transport/getting-started/authentication.mdx
+++ b/src/pages/docs/ai-transport/getting-started/authentication.mdx
@@ -5,7 +5,11 @@ meta_keywords: "AI Transport, authentication setup, Ably JWT, authCallback, toke
 intro: "AI Transport authenticates through your existing auth: your server validates the user and signs an Ably token, and the browser's Ably client fetches it through `authCallback`and refreshes it before expiry."
 ---
 
+<Aside data-type='note'>
 This page is the practical setup. For the conceptual model (the three auth layers, capabilities, token lifecycle, cancel authorisation), see the [authentication concept](/docs/ai-transport/concepts/authentication).
+</Aside>
+
+AI Transport reuses the authentication you already have. Your server validates the user and signs a short-lived Ably JWT, scoped to the channels that user can reach. The browser's Ably client fetches that token through an `authCallback` and refreshes it before it expires, so the connection stays authenticated for the whole conversation. The steps below wire up the server endpoint, the client, and the separate POST that wakes the agent.
 
 <Aside data-type='important'>
 Never embed an Ably API key in client-side code. API keys do not expire and are not suitable for untrusted clients.
diff --git a/src/pages/docs/ai-transport/getting-started/core-sdk.mdx b/src/pages/docs/ai-transport/getting-started/core-sdk.mdx
index 32849f8f6d..6d11529c04 100644
--- a/src/pages/docs/ai-transport/getting-started/core-sdk.mdx
+++ b/src/pages/docs/ai-transport/getting-started/core-sdk.mdx
@@ -18,7 +18,7 @@ To use AI Transport with Vercel's `useChat` for message management, see [Get sta
 
 ## Prerequisites <a id="prerequisites"/>
 
-- Node.js 20 or later.
+- Node.js 22 or later.
 - An [Ably account](https://ably.com/sign-up) with an API key.
 - An Anthropic API key, or any other model provider you prefer.
 
@@ -36,6 +36,16 @@ Create an auth endpoint at `/api/auth/token` that returns an Ably JWT to the cli
 
 The client below uses `authUrl: '/api/auth/token'` to fetch tokens from this endpoint.
 
+## Configure the channel rule <a id="channel-rule"/>
+
+AI Transport streams each response by appending tokens to a single channel message. That requires the **Message annotations, updates, deletes, and appends** channel rule (`mutableMessages`) on the namespace your conversations live on.
+
+In your Ably dashboard, enable **Message annotations, updates, deletes, and appends** on the `conversations` namespace. See [Configure the channel rule](/docs/ai-transport/getting-started/channel-rules) for the dashboard, Control API, and CLI steps.
+
+<Aside data-type='important'>
+This is a one-time setup per Ably app. Without the rule, the first token append fails with error `93002` and no tokens stream. The `channelName` you set below must live in a namespace with this rule enabled.
+</Aside>
+
 ## Create the agent route <a id="agent-route"/>
 
 Create `app/api/chat/route.ts`. The agent receives an [Invocation](/docs/ai-transport/concepts/invocations), creates an [AgentSession](/docs/ai-transport/api/javascript/core/agent-session), starts a [Run](/docs/ai-transport/concepts/runs), hydrates the conversation, pipes the LLM stream, and ends the Run.
diff --git a/src/pages/docs/ai-transport/getting-started/vercel-ai-sdk.mdx b/src/pages/docs/ai-transport/getting-started/vercel-ai-sdk.mdx
index 367e0e942d..5156d0d703 100644
--- a/src/pages/docs/ai-transport/getting-started/vercel-ai-sdk.mdx
+++ b/src/pages/docs/ai-transport/getting-started/vercel-ai-sdk.mdx
@@ -24,7 +24,7 @@ For direct access to the conversation tree, branching, and pagination, see [Get
 
 ## Prerequisites <a id="prerequisites"/>
 
-- Node.js 20 or later.
+- Node.js 22 or later.
 - An [Ably account](https://ably.com/sign-up) with an API key.
 - An Anthropic API key, or any other model provider supported by Vercel AI SDK.
 
@@ -42,6 +42,16 @@ Create an auth endpoint at `/api/auth/token` that returns an Ably JWT to the cli
 
 The client below uses `authUrl: '/api/auth/token'` to fetch tokens from this endpoint.
 
+## Configure the channel rule <a id="configure-the-channel-rule"/>
+
+AI Transport streams each response by appending tokens to a single channel message. That requires the **Message annotations, updates, deletes, and appends** channel rule (`mutableMessages`) on the namespace your conversations live on.
+
+In your Ably dashboard, enable **Message annotations, updates, deletes, and appends** on the `conversations` namespace. See [Configure the channel rule](/docs/ai-transport/getting-started/channel-rules) for the dashboard, Control API, and CLI steps.
+
+<Aside data-type='important'>
+This is a one-time setup per Ably app. Without the rule, the first token append fails with error `93002` and no tokens stream. The `channelName` you set below must live in a namespace with this rule enabled.
+</Aside>
+
 ## Create the agent route <a id="create-the-agent-route"/>
 
 Create `app/api/chat/route.ts`. The agent receives an [Invocation](/docs/ai-transport/concepts/invocations), creates an [AgentSession](/docs/ai-transport/api/javascript/core/agent-session) pre-bound to `UIMessageCodec`, starts a Run, hydrates the conversation, pipes the LLM stream, and ends the Run.
@@ -107,30 +117,37 @@ export async function POST(req) {
 
 ## Create the chat component <a id="create-the-chat-component"/>
 
-Create `app/chat.tsx`. The component uses Vercel's `useChat` hook with `createChatTransport` from `@ably/ai-transport/vercel`. The Vercel wrapper owns the agent-invocation POST; `useChat` calls into it as if it were the default HTTP transport.
+Create `app/chat.tsx`. The component reads the chat transport from the nearest [`ChatTransportProvider`](/docs/ai-transport/api/react/vercel/chat-transport-provider) with [`useChatTransport`](/docs/ai-transport/api/react/vercel/use-chat-transport) and passes it to Vercel's `useChat` hook. The transport owns the agent-invocation POST; `useChat` calls into it as if it were the default HTTP transport. [`useMessageSync`](/docs/ai-transport/api/react/vercel/use-message-sync) feeds channel updates back into `useChat`, so other clients see messages they did not publish.
 
 <Code>
 ```javascript
 'use client';
 
-import { useMemo, useState } from 'react';
+import { useState } from 'react';
 import { useChat } from '@ai-sdk/react';
-import { useClientSession } from '@ably/ai-transport/react';
-import { createChatTransport } from '@ably/ai-transport/vercel';
+import { useChatTransport, useMessageSync } from '@ably/ai-transport/vercel/react';
 
-export function Chat({ chatId }) {
+export function Chat() {
   const [input, setInput] = useState('');
-  const { session } = useClientSession();
+  const { session, chatTransport, chatTransportError } = useChatTransport();
 
-  const chatTransport = useMemo(() => createChatTransport(session), [session]);
-
-  const { messages, sendMessage, status, stop } = useChat({
-    id: chatId,
+  const { messages, setMessages, sendMessage, status } = useChat({
     transport: chatTransport,
   });
 
+  useMessageSync({ setMessages });
+
+  if (chatTransportError) {
+    return <div>Failed to connect: {chatTransportError.message}</div>;
+  }
+
   const isStreaming = status === 'submitted' || status === 'streaming';
 
+  const stop = () => {
+    const activeRun = session.view.runs().find((run) => run.status === 'active');
+    if (activeRun) void session.cancel(activeRun.runId);
+  };
+
   return (
     <div>
       {messages.map((msg) => (
@@ -164,7 +181,7 @@ export function Chat({ chatId }) {
 
 ## Wire it together <a id="wire-it-together"/>
 
-Create `app/page.tsx`. `Providers` sets up an authenticated Ably client. [`ClientSessionProvider`](/docs/ai-transport/api/react/core/providers) constructs the underlying [`ClientSession`](/docs/ai-transport/api/javascript/core/client-session) bound to the channel.
+Create `app/page.tsx`. `Providers` sets up an authenticated Ably client. [`ChatTransportProvider`](/docs/ai-transport/api/react/vercel/chat-transport-provider) constructs the underlying [`ClientSession`](/docs/ai-transport/api/javascript/core/client-session) bound to the channel and the [`ChatTransport`](/docs/ai-transport/api/javascript/vercel/chat-transport) over it. It POSTs invocations to `/api/chat` by default, matching the agent route above; set `api` to point elsewhere.
 
 Update `channelName` to match a namespace with the AIT [channel rules](/docs/ai-transport/getting-started/channel-rules) configured.
 
@@ -175,8 +192,7 @@ Update `channelName` to match a namespace with the AIT [channel rules](/docs/ai-
 import { useEffect, useState } from 'react';
 import * as Ably from 'ably';
 import { AblyProvider } from 'ably/react';
-import { ClientSessionProvider } from '@ably/ai-transport/react';
-import { UIMessageCodec } from '@ably/ai-transport/vercel';
+import { ChatTransportProvider } from '@ably/ai-transport/vercel/react';
 import { Chat } from './chat';
 
 function Providers({ children }) {
@@ -193,12 +209,11 @@ function Providers({ children }) {
 }
 
 export default function Page() {
-  const chatId = 'conversations:my-chat-session';
   return (
     <Providers>
-      <ClientSessionProvider channelName={chatId} codec={UIMessageCodec}>
-        <Chat chatId={chatId} />
-      </ClientSessionProvider>
+      <ChatTransportProvider channelName="conversations:my-chat-session">
+        <Chat />
+      </ChatTransportProvider>
     </Providers>
   );
 }