Overview

Build UIs that display real-time subagent streams, task progress, and sandbox for Deep Agents

Build frontends that visualize deep agent workflows in real time. These patterns show how to render subagent progress, task planning, streaming content, and IDE-like sandbox experiences from agents created with createDeepAgent.

Deep agents are most useful when the UI makes delegation visible. Instead of showing a single opaque assistant bubble, the LangChain SDKs expose the coordinator, subagent discovery, custom state, and sandbox-backed artifacts so users can inspect how a long-running task is being decomposed and completed.

These patterns use the v1 frontend SDK packages. If you are using earlier versions, see the migration guides for React, Vue, Svelte, and Angular.

Architecture

Deep Agents use a coordinator-worker architecture. The main agent plans tasks and delegates to specialized subagents, each running in isolation. On the frontend, the v1 stream handle surfaces coordinator messages on the root stream and exposes subagent discovery snapshots for scoped subagent views.

from deepagents import create_deep_agent

agent = create_deep_agent(
    model="google_genai:gemini-3.5-flash",
    tools=[get_weather],
    system_prompt="You are a helpful assistant",
    subagents=[
        {
            "name": "researcher",
            "description": "Research assistant",
        }
    ],
)

On the frontend, connect with useStream the same way as with createAgent. Pass a type parameter for type-safe stream state. Deep agent patterns use stream.subagents, selector helpers such as useMessages(stream, subagent), and custom state values like stream.values.todos to render subagent-specific UIs.

import { useStream } from "@langchain/react";

function App() {
  const stream = useStream<typeof agent>({
    apiUrl: "http://localhost:2024",
    assistantId: "agent",
  });

  // Deep agent state beyond messages
  const todos = stream.values?.todos;
  const subagents = [...stream.subagents.values()];
}

What the SDK exposes

Deep agent UIs usually need more than the final answer. The frontend SDK gives you structured projections for the parts of the run users care about:

Projection	Use it for
stream.messages	The coordinator conversation and final synthesis.
stream.subagents	Live discovery of specialist workers, including status and task metadata.
stream.values	Shared state such as todos, plans, report sections, sandbox metadata, or any custom key your agent writes.
Tool-call state	Rendering filesystem, search, browser, or domain tools as cards with progress and results.
Interrupts	Pausing delegated work for user approval or missing input without losing the run state.

This lets you build interfaces that feel closer to an IDE, task board, or workflow monitor than a plain chat transcript.

Patterns

Subagent streaming

Display specialist subagents with streaming content, progress tracking, and collapsible cards.

Todo list

Track agent progress with a real-time todo list synced from agent state.

Sandbox

Build an IDE-like UI with a file browser, code viewer, and diff panel backed by a sandbox.

Related patterns

The LangChain frontend patterns, including markdown messages, tool calling, and human-in-the-loop, all work with deep agents too. Deep Agents are built on the same LangGraph runtime, so useStream provides the same core API.

For lower-level graph visualizations, see the LangGraph frontend patterns. They show how to map graph nodes and state keys directly to UI components.

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