@tanstack/ai-svelte

npm install @tanstack/ai-svelte

import { createChat, fetchServerSentEvents } from "@tanstack/ai-svelte";
import {
  clientTools,
  createChatClientOptions,
  type InferChatMessages,
} from "@tanstack/ai-client";

// In <script> block
const updateUI = updateUIDef.client((input) => {
  notification = input.message;
  return { success: true };
});

const tools = clientTools(updateUI);

const chatOptions = createChatClientOptions({
  connection: fetchServerSentEvents("/api/chat"),
  tools,
});

// Fully typed messages!
type ChatMessages = InferChatMessages<typeof chatOptions>;

const chat = createChat(chatOptions);
// Access: chat.messages, chat.sendMessage, chat.isLoading, chat.error

interface CreateChatReturn {
  readonly messages: UIMessage[];
  sendMessage: (content: string | MultimodalContent) => Promise<void>;
  append: (message: ModelMessage | UIMessage) => Promise<void>;
  addToolResult: (result: {
    toolCallId: string;
    tool: string;
    output: any;
    state?: "output-available" | "output-error";
    errorText?: string;
  }) => Promise<void>;
  addToolApprovalResponse: (response: {
    id: string;
    approved: boolean;
  }) => Promise<void>;
  reload: () => Promise<void>;
  stop: () => void;
  readonly isLoading: boolean;
  readonly error: Error | undefined;
  readonly status: ChatClientState;
  readonly isSubscribed: boolean;
  readonly connectionStatus: ConnectionStatus;
  readonly sessionGenerating: boolean;
  setMessages: (messages: UIMessage[]) => void;
  clear: () => void;
  updateBody: (body: Record<string, any>) => void;
}

import {
  fetchServerSentEvents,
  fetchHttpStream,
  stream,
  type ConnectionAdapter,
} from "@tanstack/ai-svelte";

<script lang="ts">
  import { createChat, fetchServerSentEvents } from "@tanstack/ai-svelte";

  let input = $state("");

  const chat = createChat({
    connection: fetchServerSentEvents("/api/chat"),
  });

  const handleSubmit = (e: Event) => {
    e.preventDefault();
    if (input.trim() && !chat.isLoading) {
      chat.sendMessage(input);
      input = "";
    }
  };
</script>

<div>
  <div>
    {#each chat.messages as message (message.id)}
      <div>
        <strong>{message.role}:</strong>
        {#each message.parts as part, idx}
          {#if part.type === "thinking"}
            <div class="text-sm text-gray-500 italic">
              Thinking: {part.content}
            </div>
          {:else if part.type === "text"}
            <span>{part.content}</span>
          {/if}
        {/each}
      </div>
    {/each}
  </div>
  <form onsubmit={handleSubmit}>
    <input bind:value={input} disabled={chat.isLoading} />
    <button type="submit" disabled={chat.isLoading}>Send</button>
  </form>
</div>

<script lang="ts">
  import { createChat, fetchServerSentEvents } from "@tanstack/ai-svelte";

  const chat = createChat({
    connection: fetchServerSentEvents("/api/chat"),
  });
</script>

<div>
  {#each chat.messages as message (message.id)}
    {#each message.parts as part}
      {#if part.type === "tool-call" && part.state === "approval-requested" && part.approval}
        <div>
          <p>Approve: {part.name}</p>
          <button
            onclick={() =>
              chat.addToolApprovalResponse({
                id: part.approval.id,
                approved: true,
              })}
          >
            Approve
          </button>
          <button
            onclick={() =>
              chat.addToolApprovalResponse({
                id: part.approval.id,
                approved: false,
              })}
          >
            Deny
          </button>
        </div>
      {/if}
    {/each}
  {/each}
</div>

<script lang="ts">
  import { createChat, fetchServerSentEvents } from "@tanstack/ai-svelte";
  import {
    clientTools,
    createChatClientOptions,
    type InferChatMessages,
  } from "@tanstack/ai-client";
  import { updateUIDef, saveToStorageDef } from "./tool-definitions";

  let notification = $state(null);

  // Create client implementations
  const updateUI = updateUIDef.client((input) => {
    // input is fully typed!
    notification = { message: input.message, type: input.type };
    return { success: true };
  });

  const saveToStorage = saveToStorageDef.client((input) => {
    localStorage.setItem(input.key, input.value);
    return { saved: true };
  });

  // Create typed tools array (no 'as const' needed!)
  const tools = clientTools(updateUI, saveToStorage);

  const chat = createChat({
    connection: fetchServerSentEvents("/api/chat"),
    tools, // Automatic execution, full type safety
  });
</script>

<div>
  {#each chat.messages as message (message.id)}
    {#each message.parts as part}
      {#if part.type === "tool-call" && part.name === "updateUI"}
        <div>Tool executed: {part.name}</div>
      {/if}
    {/each}
  {/each}
</div>

import { createGeneration, fetchServerSentEvents } from "@tanstack/ai-svelte";

const gen = createGeneration({
  connection: fetchServerSentEvents("/api/generate/custom"),
});

// gen.generate({ prompt: 'Hello' })
// gen.result, gen.isLoading, gen.error, gen.status

import {
  clientTools,
  createChatClientOptions,
  type InferChatMessages,
} from "@tanstack/ai-client";

// Create typed tools array (no 'as const' needed!)
const tools = clientTools(tool1, tool2);

const chatOptions = createChatClientOptions({
  connection: fetchServerSentEvents("/api/chat"),
  tools,
});

type Messages = InferChatMessages<typeof chatOptions>;