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@standardagents/react

React hooks and components for Standard Agents Builder - connect to AI agent threads with real-time updates

Overview

The @standardagents/react package provides React hooks and components for building UIs that connect to Standard Agents Builder threads. It handles real-time message streaming, custom event listening, and workblock transformation for tool visualization.

Key Features
  • Real-time WebSocket updates for live message streaming
  • Context-based architecture with ThreadProvider
  • Workblock transformation for UI-friendly tool displays
  • Custom event system for backend-to-frontend communication
  • File uploads and attachments for sending images to the LLM
  • TypeScript support with full type definitions
  • Works with any React framework (Next.js, Remix, Vite, etc.)

Installation

npm

npm
npm install @standardagents/react

pnpm

pnpm
pnpm add @standardagents/react

yarn

yarn
yarn add @standardagents/react

Quick Start

import {
  AgentBuilderProvider,
  ThreadProvider,
  useThread,
} from "@standardagents/react"

function App() {
  return (
    <AgentBuilderProvider config={{ endpoint: "https://your-api.com/api" }}>
      <ThreadProvider threadId="123e4567-e89b-12d3-a456-426614174000">
        <ChatInterface />
      </ThreadProvider>
    </AgentBuilderProvider>
  )
}

function ChatInterface() {
  const { messages, sendMessage, status } = useThread()

  const handleSend = async (text: string) => {
    await sendMessage({ role: "user", content: text })
  }

  return (
    <div>
      <p>Status: {status}</p>
      {messages.map((msg) => (
        <div key={msg.id}>
          <strong>{msg.role}:</strong> {msg.content}
        </div>
      ))}
      <input onKeyDown={(e) => e.key === "Enter" && handleSend(e.currentTarget.value)} />
    </div>
  )
}

Core Providers

AgentBuilderProvider

Root provider that configures the API endpoint for all child components.

<AgentBuilderProvider config={{ endpoint: "https://api.example.com/api" }}>
  {children}
</AgentBuilderProvider>

Props:

Prop Type Required Description
config.endpoint string Yes The API endpoint URL
children ReactNode Yes Child components

ThreadProvider

Establishes a WebSocket connection to a specific thread and provides context for child components.

<ThreadProvider
  threadId="123e4567-e89b-12d3-a456-426614174000"
  preload={true}
  live={true}
  useWorkblocks={false}
  depth={0}
  includeSilent={false}
>
  <ChatInterface />
</ThreadProvider>

Props:

Prop Type Default Description
threadId string Required The thread ID to connect to
preload boolean true Fetch existing messages on mount
live boolean true Enable WebSocket for live updates
useWorkblocks boolean false Transform tool calls into workblocks
useSubagentBlocks boolean false Transform messages into subagent blocks
depth number 0 Max message depth (0 = top-level only)
includeSilent boolean false Include silent messages
endpoint string - Override endpoint from AgentBuilderProvider

Hooks

useThread

Hook to access the full thread context. Must be used within a ThreadProvider.

import { useThread } from "@standardagents/react"

function ChatMessages() {
  const {
    // Messages & State
    messages,
    workblocks,
    loading,
    error,
    status,
    runStatus,

    // Actions
    sendMessage,
    stopExecution,
    deleteMessage,

    // Custom Events
    onEvent,

    // File Management (uploads to filesystem)
    files,
    addFiles,
    removeFile,
    getFileUrl,
    getPreviewUrl,

    // Attachment Management (sent to LLM)
    attachments,
    addAttachment,
    removeAttachment,
    clearAttachments,
  } = useThread()

  return (
    <div>
      <p>Status: {status}</p>
      {loading && <p>Loading...</p>}
      {messages.map((msg) => (
        <MessageBubble key={msg.id} message={msg} />
      ))}
    </div>
  )
}

Method Reference

sendMessage

Send a message to the thread with the pending attachments. The pending queue clears when sending starts. A failed send restores the queue for the same session.

const { sendMessage, attachments, addAttachment } = useThread()

// Simple text message
await sendMessage({ role: 'user', content: 'Hello!' })

// With attachments (call addAttachment first)
// Attachments are auto-included and cleared after send
addAttachment(imageFile)
await sendMessage({ role: 'user', content: 'What is in this image?' })

Sending returns a queued acknowledgement. Its messageId identifies the accepted message. Read the message from thread state after its message_data frame arrives.

Signature:

sendMessage(payload: Omit<SendMessagePayload, 'attachments'>): Promise<SendMessageResponse>

interface SendMessageResponse {
  status: 'queued'
  messageId: string
}

interface SendMessagePayload {
  role: 'user' | 'assistant' | 'system'
  content: string
  silent?: boolean
}

Optimistic UI: When you call sendMessage(), an optimistic message with attachment previews is shown immediately. The real message replaces it when confirmed by the server via WebSocket.


addAttachment

Queue file(s) to be sent with the next message. Files are NOT uploaded immediately - they're held locally with preview URLs and sent inline (base64) when sendMessage() is called.

Use this for images/files that should be sent directly to the LLM.

const { addAttachment, attachments } = useThread()

// Single file
const handleFileSelect = (e: React.ChangeEvent<HTMLInputElement>) => {
  if (e.target.files?.[0]) {
    addAttachment(e.target.files[0])
  }
}

// Multiple files
addAttachment(Array.from(fileInput.files))

// FileList directly
addAttachment(e.target.files)

// Show previews for pending attachments
{attachments.map(a => (
  <div key={a.id}>
    {a.isImage && a.previewUrl && (
      <img src={a.previewUrl} alt={a.name} />
    )}
    <span>{a.name}</span>
    <button onClick={() => removeAttachment(a.id)}>Remove</button>
  </div>
))}

Signature:

addAttachment(files: File | File[] | FileList): void

PendingAttachment Type:

interface PendingAttachment {
  id: string              // Temporary ID
  file: File              // Original file object
  name: string
  mimeType: string
  size: number
  isImage: boolean
  previewUrl: string | null  // Object URL for image preview
  width?: number
  height?: number
}

removeAttachment

Remove a pending attachment before sending.

const { removeAttachment, attachments } = useThread()

<button onClick={() => removeAttachment(attachment.id)}>Remove</button>

Signature:

removeAttachment(id: string): void

clearAttachments

Remove all pending attachments.

const { clearAttachments, attachments } = useThread()

{attachments.length > 0 && (
  <button onClick={clearAttachments}>Clear All</button>
)}

Signature:

clearAttachments(): void

addFiles

Upload files to the thread's filesystem. Files are uploaded immediately and stored persistently.

Use this for documents/files that should be stored on the thread but NOT sent directly to the LLM.

const { addFiles, files, getPreviewUrl } = useThread()

// Upload files to filesystem
addFiles(fileInput.files)

// Display uploaded files
{files.map(f => (
  <div key={f.id}>
    {f.isImage && <img src={getPreviewUrl(f)} alt={f.name} />}
    <span>{f.name}</span>
    <span>{f.status}</span> {/* 'uploading' | 'ready' | 'committed' | 'error' */}
  </div>
))}

Signature:

addFiles(files: File[] | FileList): void

ThreadFile Type:

interface ThreadFile {
  id: string
  name: string
  mimeType: string
  size: number
  isImage: boolean
  localPreviewUrl: string | null
  status: 'uploading' | 'ready' | 'committed' | 'error'
  error?: string
  path?: string
  width?: number
  height?: number
  messageId?: string
}

removeFile

Remove a pending file upload (cannot remove already committed files). A file that is still uploading has its HTTP request aborted, and it never reports ready or error afterwards.

const { removeFile } = useThread()

<button onClick={() => removeFile(file.id)}>Cancel Upload</button>

File URL Helpers

const { getFileUrl, getThumbnailUrl, getPreviewUrl } = useThread()

// Full file URL (for download/viewing)
const url = getFileUrl(file)

// Thumbnail URL (for images)
const thumb = getThumbnailUrl(file)

// Preview URL (smart - uses local preview for pending, thumbnail for committed)
const preview = getPreviewUrl(file)

stopExecution

Stop the current agent execution. Calling it when nothing is running is safe: the request succeeds and the thread is left unchanged.

const { stopExecution } = useThread()

<button onClick={stopExecution}>Stop</button>

deleteMessage

Delete a message from the thread. The message is optimistically removed from the UI immediately. If the server request fails, the message is restored.

const { deleteMessage, messages } = useThread()

async function handleDelete(messageId: string) {
  try {
    await deleteMessage(messageId)
  } catch (err) {
    console.error('Failed to delete:', err)
  }
}

// Usage
{messages.map(msg => (
  <div key={msg.id}>
    <span>{msg.content}</span>
    <button onClick={() => handleDelete(msg.id)}>Delete</button>
  </div>
))}

Signature:

deleteMessage(messageId: string): Promise<void>

Note: Server-side attachment files are automatically cleaned up when a message is deleted.


onEvent / subscribeToEvent

Subscribe to custom events emitted by the agent.

const { onEvent } = useThread()

useEffect(() => {
  const unsubscribe = onEvent<{ status: string }>('progress', (data) => {
    console.log('Progress:', data.status)
  })
  return unsubscribe
}, [])

addFiles vs addAttachment

Feature addFiles() addAttachment()
Purpose Filesystem storage Send to LLM
Upload timing Immediate On sendMessage()
Storage Thread filesystem (persistent) Thread filesystem (persistent), referenced by the message
Image processing None (raw storage) Server-side resize/optimize
Use case Documents, persistent files Chat images to LLM

Message uploads carry base64 bytes in the request.

Real-time File Synchronization

The files array from useThread() automatically stays synchronized with the server. When files are added, modified, or deleted on the thread (by the agent, tools, or other clients), the files array updates in real-time via WebSocket.

File Events

The SDK listens for three file-related events:

Event Description
file_created A new file was added to the thread filesystem
file_updated An existing file was modified
file_deleted A file was removed from the thread filesystem

Custom File Event Handling

You can also subscribe to these events directly for custom handling:

const { onEvent } = useThread()

useEffect(() => {
  const unsubscribe = onEvent<{ path: string; file: { name: string; mimeType: string; size: number } }>('file_created', (data) => {
    console.log('File created:', data.path)
    // Custom notification, analytics, etc.
  })
  return unsubscribe
}, [onEvent])

How It Works

  1. Initial load: When ThreadProvider mounts, it fetches the current file list from the server
  2. Live updates: WebSocket events update the files array as changes occur
  3. Optimistic UI: Local uploads via addFiles() appear immediately as "uploading" then transition to "committed"
  4. Deduplication: Server files take priority over local pending files with the same path

useThread Return Value

Full ThreadContextValue:

Property Type Description
threadId string The current thread ID
messages Message[] Loaded messages from the thread
workblocks ThreadMessage[] Messages transformed to workblocks (if useWorkblocks is true)
subagentBlocks SubagentThreadMessage[] Messages transformed to subagent blocks (if useSubagentBlocks is true)
groupedMessages GroupedThreadMessage[] The active grouped view: subagent blocks, then workblocks, then raw messages
loading boolean Whether messages are loading
isLoading boolean Alias for loading
error Error | null Any error that occurred
status ConnectionStatus WebSocket connection status
connectionStatus ConnectionStatus Alias for status
runStatus ThreadStatus | null Run status that the server sends: a snapshot on each connect, then each change. null until the first status arrives, and when live is false
options ThreadProviderOptions Resolved options from ThreadProvider props
sendMessage (payload) => Promise<SendMessageResponse> Send a message (auto-includes attachments)
stopExecution () => Promise<void> Stop current execution
deleteMessage (messageId: string) => Promise<void> Delete a message (optimistic UI)
onEvent <T>(type, listener) => () => void Subscribe to custom events
subscribeToEvent <T>(type, listener) => () => void Alias for onEvent
files ThreadFile[] All files (pending uploads + committed)
addFiles (files) => void Upload files to filesystem
removeFile (id) => void Remove a pending file
getFileUrl (file) => string Get file URL
getThumbnailUrl (file) => string Get thumbnail URL
getPreviewUrl (file) => string | null Get preview URL
attachments PendingAttachment[] Pending attachments for next message
addAttachment (files) => void Add attachment(s) for next message
removeAttachment (id) => void Remove a pending attachment
clearAttachments () => void Clear all pending attachments

ConnectionStatus:

type ConnectionStatus = 'connecting' | 'connected' | 'disconnected' | 'reconnecting'

ThreadStatus:

interface ThreadStatus {
  state: 'idle' | 'running' | 'failed'
  since: number            // microseconds since epoch
  reason?: string | null   // stop reason of the last run; null while running
}

status reports the WebSocket connection. runStatus reports the agent run. Read runStatus?.state === 'running' to find out whether a run is active.

useThreadId

Returns the current thread ID from context.

import { useThreadId } from "@standardagents/react"

function ThreadInfo() {
  const threadId = useThreadId()
  return <span>Thread: {threadId}</span>
}

Custom Events

Listen for custom events emitted by the backend using onEvent from useThread():

import { useState, useEffect, useCallback } from "react"
import { useThread } from "@standardagents/react"

function GamePreview() {
  const { onEvent } = useThread()
  const [gameStatus, setGameStatus] = useState<{ success: boolean } | null>(null)

  useEffect(() => {
    // Subscribe to custom events - returns unsubscribe function
    const unsubscribe = onEvent<{ success: boolean }>('game_built', (data) => {
      setGameStatus(data)
    })
    return unsubscribe
  }, [onEvent])

  return gameStatus?.success ? <GameIframe /> : <LoadingSpinner />
}

Backend Integration:

Tools and hooks emit custom thread events through their ThreadState parameter:

// Inside a tool or hook's execute callback:
state.emit("game_built", { success: true })

Workblocks

Workblocks are a UI-friendly transformation of tool calls. When useWorkblocks: true, consecutive assistant messages with tool calls are grouped into workblocks.

Raw Messages

assistant (with tool_calls) → tool result → tool result → assistant (final)

Transformed Workblocks

workblock {
  workItems: [tool_call, tool_result, tool_call, tool_result]
  status: 'completed' | 'pending' | 'failed'
} → assistant (final)

WorkMessage Type

interface WorkMessage {
  id: string
  type: "workblock"
  content: string | null
  reasoning_content?: string | null
  workItems: WorkItem[]
  status: "pending" | "completed" | "failed"
  created_at: number
  depth?: number
}

interface WorkItem {
  id: string
  type: "tool_call" | "tool_result" | "content"
  name?: string
  content: string | null
  status?: "pending" | "success" | "error" | null
  tool_call_id?: string
}

Rendering Workblocks

function MessageList() {
  const { workblocks } = useThread()

  return (
    <>
      {workblocks.map((msg) => {
        if ("type" in msg && msg.type === "workblock") {
          return <WorkBlockDisplay key={msg.id} workblock={msg} />
        }
        return <MessageBubble key={msg.id} message={msg} />
      })}
    </>
  )
}

function WorkBlockDisplay({ workblock }: { workblock: WorkMessage }) {
  return (
    <div className={`workblock ${workblock.status}`}>
      {workblock.workItems.map((item) => (
        <div key={item.id}>
          {item.type === "tool_call" ? `Calling ${item.name}...` : item.content}
        </div>
      ))}
    </div>
  )
}

TypeScript Support

The package is written in TypeScript and includes full type definitions.

import type {
  // Core types
  Message,
  WorkMessage,
  WorkItem,
  ThreadMessage,
  Thread,

  // Configuration
  AgentBuilderConfig,
  GetMessagesOptions,
  SendMessagePayload,
  ThreadProviderOptions,

  // Attachment types
  PendingAttachment,
  AttachmentPayload,
  AttachmentRef,
  ThreadFile,

  // Run status
  ThreadStatus,
  ThreadRunState,

  // WebSocket events
  MessageDataEvent,
  MessageChunkEvent,
  ErrorEvent,
  ThreadEvent,
  MessageStreamEvent,
  LogDataEvent,
  CustomEvent,
  StoppedByUserEvent,
  LogStreamEvent,

  // WebSocket callbacks
  MessageWebSocketCallbacks,
  LogWebSocketCallbacks,
} from "@standardagents/react"

// Connection status type
import type { ConnectionStatus } from "@standardagents/react"

Message Type

interface Message {
  id: string
  role: "system" | "user" | "assistant" | "tool"
  content: string | null
  name?: string | null
  tool_calls?: string | null          // JSON array
  tool_call_id?: string | null
  log_id?: string | null
  created_at: number                  // microseconds
  request_sent_at?: number | null
  response_completed_at?: number | null
  status?: "pending" | "completed" | "failed"
  silent?: boolean
  tool_status?: "success" | "error" | null
  reasoning_content?: string | null
  reasoning_details?: string | null   // JSON array
  parent_id?: string | null
  depth?: number
  attachments?: string | AttachmentRef[] | null
}

HTTP message reads and message_data frames carry attachment arrays. The string form in the type is tolerance for older runtimes, whose frames could carry the stored JSON string. Use parseAttachments(message) when rendering SDK state.

Complete Example

The example creates a thread with AgentBuilderClient.createThread() and then mounts ThreadProvider for that thread. Set AGENT_ID to the name of an agent in your project. It reads runStatus to disable the input while a run is active.

View Complete Chat Interface Example with Image Attachments
import { useState } from "react"
import type { ChangeEvent } from "react"
import {
  AgentBuilderClient,
  AgentBuilderProvider,
  ThreadProvider,
  useThread,
  useThreadId,
  parseAttachments,
} from "@standardagents/react"
import type { ThreadMessage, Message, WorkMessage } from "@standardagents/react"

const ENDPOINT = "/api"

// Use the name of an agent in your project
const AGENT_ID = "support_agent"

const client = new AgentBuilderClient(ENDPOINT)

async function createThread(): Promise<string> {
  const { threadId } = await client.createThread({ agent_id: AGENT_ID })
  return threadId
}

function App() {
  const [threadId, setThreadId] = useState<string | null>(null)

  return (
    <AgentBuilderProvider config={{ endpoint: ENDPOINT }}>
      {threadId ? (
        <ThreadProvider threadId={threadId} useWorkblocks>
          <ChatInterface />
        </ThreadProvider>
      ) : (
        <button onClick={() => createThread().then(setThreadId)}>
          Start Chat
        </button>
      )}
    </AgentBuilderProvider>
  )
}

function ChatInterface() {
  const {
    workblocks,
    sendMessage,
    stopExecution,
    status,
    runStatus,
    loading,
    // Attachments for sending to LLM
    attachments,
    addAttachment,
    removeAttachment,
  } = useThread()

  const [input, setInput] = useState("")

  const isRunning = runStatus?.state === "running"

  const handleSend = async () => {
    if (!input.trim() || isRunning) return
    await sendMessage({ role: "user", content: input })
    setInput("")
  }

  const handleFileSelect = (e: ChangeEvent<HTMLInputElement>) => {
    if (e.target.files?.length) {
      addAttachment(e.target.files)
    }
  }

  return (
    <div>
      <p>Status: {status} {loading && "(loading...)"}</p>

      <MessageList messages={workblocks} />

      {/* Pending attachments preview */}
      {attachments.length > 0 && (
        <div className="attachment-preview">
          {attachments.map((a) => (
            <div key={a.id} className="attachment-item">
              {a.isImage && a.previewUrl && (
                <img src={a.previewUrl} alt={a.name} width={100} />
              )}
              <span>{a.name}</span>
              <button onClick={() => removeAttachment(a.id)}>×</button>
            </div>
          ))}
        </div>
      )}

      <div className="input-row">
        <input
          type="file"
          accept="image/*"
          multiple
          onChange={handleFileSelect}
        />
        <input
          value={input}
          onChange={(e) => setInput(e.target.value)}
          onKeyDown={(e) => e.key === "Enter" && handleSend()}
          disabled={isRunning}
          placeholder="Type a message..."
        />
        {isRunning ? (
          <button onClick={stopExecution}>Stop</button>
        ) : (
          <button onClick={handleSend}>Send</button>
        )}
      </div>
    </div>
  )
}

function MessageList({ messages }: { messages: ThreadMessage[] }) {
  return (
    <div>
      {messages.map((msg) => {
        if ("type" in msg && msg.type === "workblock") {
          return <WorkBlock key={msg.id} block={msg} />
        }
        const message = msg as Message
        if (message.role === "tool") return null
        return (
          <div key={message.id} className={message.role}>
            {message.content}
            {message.attachments && <MessageAttachments message={message} />}
          </div>
        )
      })}
    </div>
  )
}

function MessageAttachments({ message }: { message: Message }) {
  const threadId = useThreadId()
  const parsed = parseAttachments(message)
  return (
    <div className="message-attachments">
      {parsed.map((a) => (
        <img
          key={a.id}
          src={a.localPreviewUrl || client.getFileUrl(threadId, a.path)}
          alt={a.name}
        />
      ))}
    </div>
  )
}

function WorkBlock({ block }: { block: WorkMessage }) {
  return (
    <div className={`workblock ${block.status}`}>
      {block.workItems.map((item) => (
        <div key={item.id}>
          {item.type === "tool_call" ? (
            <span>Tool: {item.name}</span>
          ) : (
            <span>{item.content}</span>
          )}
        </div>
      ))}
    </div>
  )
}

Next Steps

Reconnect recovery

A thread provider reads the newest message page after a socket reconnect. preload controls the initial history reads. When preload is enabled, a snapshot after the first socket open closes the initial subscription gap. Recovery also reads history when preload is false. Recovery runs in the background. Snapshot results preserve in-flight events and optimistic mutations. Thread switches invalidate pending history responses. Deletions reconcile within the newest page window. Older cached rows outside that window remain until history is read again.

Thread providers adapt a framework-free ThreadSessionStore from @standardagents/client. The store owns message history, live reducers, run status, committed files, and optimistic commands. Reconnect recovery runs once in that shared store. Upload queues and display grouping stay in the framework adapter. Socket frame types are available from @standardagents/client/protocol.