Build intelligent Android apps: In-app agentic workflows

Welcome back to the blog post series "Build intelligent Android apps" where you take a basic Android app and transform it into a personalized, intelligent, and agentic experience. In our previous post you learned how to connect to the intelligence system using AppFunctions.

In this post, you will learn how to build autonomous in-app agentic workflows running in the cloud.

Sometimes a task is too complex for a single device session. For example, booking a complete holiday itinerary involves coordinating flight times, selecting hotel rooms, reserving museum tickets, and planning restaurant reservations. If you run this multi-step process directly on a mobile device, the app might get closed and lose your progress. Managing all these steps and API credentials on a phone also gets complicated quickly.

For these long-running, multi-step workflows, you can use a custom self-hosted backend. The backend executes the booking agents in the background, while the Android app connects to the session, visualizes the progress, and requests user input only when necessary.

Using a cloud-hosted agentic backend offers a few advantages:

With these benefits in mind, we added a Booking Assistant to Jetpacker that coordinates flights, hotels, museums, and restaurant reservations. Let's look at how we orchestrated a multi-agent system powered by the Agent Development Kit (ADK), with the Agent-User Interaction protocol(AG-UI) and Agent-to-User Interface protocol (A2UI) to send and display interactive cards natively in Jetpack Compose.

Here is how to define a simple agent and run it using ADK:

from google.adk import Agent
from google.adk.runners import InMemoryRunner
from google.adk.tools import FunctionTool

def search_flights(destination: str, date: str) -> list[str]:
    return ["10:00 AM", "2:00 PM"]

def reserve_flight(flight_time: str) -> str:
    return "Reserved flight at " + flight_time

flight_agent = Agent(
    name="Flight Booker",
    model="gemini-3.1-flash-lite",
    instruction="Help the user search for flights and book a reservation.",
    tools=[
        FunctionTool(search_flights),
        FunctionTool(reserve_flight, require_confirmation=True)
    ]
)

runner = InMemoryRunner(flight_agent)
async for event in runner.run_async(user_id=user_id, session_id=session_id):
    if event.content:
        print("Agent said:", event.content)

When you run an agent using this setup, ADK manages the execution steps for you. It automatically tracks the conversation context, routes messages between the user and the model, and executes the registered tools when the model requests them. This allows you to focus on writing clean procedural logic while the framework handles the orchestration in the background.

To connect this backend agent to our Jetpacker app, the server needs a way to stream updates in real time to the device, which is handled using the AG-UI protocol. The agent also needs a structured way to describe and update interactive components (like option selectors and seating grids) dynamically on the phone, which is where the A2UI protocol comes in.

AG-UI is a bidirectional transport layer protocol that standardizes message types between agents and UI clients. The agent can inform the client of lifecycle events, text messages, tool calls, and state management. The client, in turn, can send user text messages, tool call results, and custom action events back to the agent.

On the server side, it yields updates formatted as standard Server-Sent Events (like event: TEXT_MESSAGE_CONTENT containing the JSON delta). On Android, the Kotlin SDK listens to this stream and automatically maps the payloads to type-safe client events:

// https://github.com/android/ai-samples/tree/main/jetpacker/android/feature/trip/booking_assistant/src/main/kotlin/com/example/jetpacker/feature/booking_assistant/BookingAssistantViewModel.kt
import com.agui.client.agent.HttpAgent
import com.agui.client.agent.HttpAgentConfig
import com.agui.core.types.RunAgentInput
import com.agui.core.types.UserMessage
import com.agui.core.types.TextMessageStartEvent
import com.agui.core.types.TextMessageContentEvent
import com.agui.core.types.TextMessageEndEvent

val config = HttpAgentConfig(
    agentId = "booking-assistant",
    threadId = threadId,
    url = "https://<your-backend-url>"
)
val agent = HttpAgent(config, httpClient)

// Set up the input with the session thread and user instruction
val input = RunAgentInput(
    threadId = threadId,
    runId = runId,
    messages = listOf(UserMessage("Book a flight to Paris"))
)

// Run the agent flow and collect lifecycle events
agent.runAgentObservable(input)
    .collect { event ->
        when (event) {
            is TextMessageStartEvent -> { /* ... */ }
            is TextMessageContentEvent -> { /* ... */ }
            is TextMessageEndEvent -> {
                // Handle the completed message
            }
        }
    }

You can then write a UI to render these different types of standardized AG-UI events. This will give you the prototypical "Chatbot" experience:

To solve this, use the A2UI protocol. A2UI allows agents to describe the UI components to render on the client dynamically. The client app declares a catalog of components it supports, and the server sends a JSON payload specifying the component layout and properties:

{
  "version": "v0.9",
  "updateComponents": {
    "surfaceId": "Flight Reservation",
    "components": [
      {
        "id": "flight_option_picker",
        "component": "InteractiveOptionPicker",
        "properties": {
          "prompt": "Select a flight time:",
          "options": [
            "10:00 AM",
            "2:00 PM"
          ],
          "selectedIdx": null,
          "confirmBtnText": "Confirm Flight"
        }
      }
    ]
  }
}

The server specifies which catalog components to render along with their active property values, cleanly decoupling the client's visual implementation details from the agent's workflow state.

To do this, use the ADK A2UI integration. Instead of manually writing prompt instructions for every component in our catalog, the A2uiSchemaManager compiles their JSON schemas and layout instructions directly into the system prompt. This ensures the model learns the exact structure and formatting rules it must follow to generate valid A2UI payloads:

from a2ui.schema.manager import A2uiSchemaManager
from a2ui.schema.constants import VERSION_0_9
from a2ui.schema.catalog import CatalogConfig
from a2ui.basic_catalog.provider import BasicCatalog

schema_manager = A2uiSchemaManager(
    version=VERSION_0_9,
    catalogs=[
        BasicCatalog.get_config(version=VERSION_0_9),
        CatalogConfig.from_path(
            name="https://example.com/catalogs/booking_assistant/v1/catalog.json",
            catalog_path="booking_catalog.json"
        )
    ]
)

A2UI_SYSTEM_INSTRUCTION = schema_manager.generate_system_prompt(
    role_description="You are a helpful travel booking assistant.",
    ui_description="Use InteractiveOptionPicker for choices, SeatSelectionPicker for seat selection...",
    include_schema=True,
    include_examples=True,
    allowed_components=["InteractiveOptionPicker", "SeatSelectionPicker", "BookingStatus"]
)

With this generated system instruction, the LLM is grounded in the schema layout and knows exactly how to formulate component updates that the Android client is capable of rendering.

First, add the dependencies to our module's build.gradle.kts file:

// android/feature/trip/booking_assistant/build.gradle.kts
dependencies {
    implementation("androidx.a2ui:a2ui-model:1.0.0-alpha01")
    implementation("androidx.a2ui.compose:compose-runtime:1.0.0-alpha01")
    implementation("androidx.a2ui.compose:compose-ui:1.0.0-alpha01")
    implementation("androidx.compose.material3:material3-a2ui:1.0.0-alpha01")
}

Each component class in the catalog (such as BookingStatusComponent) defines how to map the properties received from the JSON payload into a Jetpack Compose composable function.

Register the custom components in a catalog:

// android/feature/trip/booking_assistant/src/main/kotlin/com/example/jetpacker/feature/booking_assistant/CustomBookingAssistantCatalog.kt

import androidx.a2ui.compose.ui.A2uiCatalog

fun bookingAssistantCatalog(): A2uiCatalog {
    return A2uiCatalog(
        catalogId = "https://example.com/catalogs/booking_assistant/v1/catalog.json",
        components = listOf(
            InteractiveOptionPickerComponent(),
            SeatSelectionPickerComponent(),
            BookingStatusComponent()
        )
    )
}

Tip: Jetpacker implements custom components (InteractiveOptionPicker, SeatSelectionPicker, BookingStatus) tailored for booking flows. If your agent uses standard elements (such as text, cards, buttons, rows, columns, checkboxes, and date-time pickers), material3-a2ui also provides materialA2uiBasicCatalogV1(...), giving you ready-to-use Material 3 implementations without writing any custom components.

Note: To keep the backend and mobile client aligned, both rely on the same catalog definition ID (https://example.com/catalogs/booking_assistant/v1/catalog.json). If you add or modify properties on the backend catalog, you must increase the version number, and update the matching Kotlin component class to prevent parsing errors.

In the BookingAssistantViewModel, process the A2UI messages using the A2uiMessageProcessor and update our active surfaces:

// android/feature/trip/booking_assistant/src/main/kotlin/com/example/jetpacker/feature/booking_assistant/BookingAssistantViewModel.kt
import androidx.lifecycle.ViewModel
import androidx.a2ui.model.processor.A2uiSurfaceModel
import androidx.a2ui.compose.ui.A2uiMessageProcessor
import kotlinx.coroutines.flow.StateFlow

class BookingAssistantViewModel : ViewModel() {
    private val messageProcessor = A2uiMessageProcessor(
        catalogs = listOf(bookingAssistantCatalog())
    )
    val activeSurfaces: StateFlow<List<A2uiSurfaceModel>> = messageProcessor.activeSurfaces
    
    init {
        viewModelScope.launch(Dispatchers.Default) { processor.collectMessages() }
    }

    // ...
}

In the Compose screen, collect these surfaces and render each one using the official A2uiSurface composable from androidx.compose.material3:material3-a2ui. A2uiSurface automatically handles reactive component state observation, Material 3 indicators, error fallbacks, and animated transitions between updates:

// android/feature/trip/booking_assistant/src/main/kotlin/com/example/jetpacker/feature/booking_assistant/BookingAssistantScreen.kt
import androidx.compose.runtime.Composable
import androidx.compose.runtime.collectAsState
import androidx.compose.foundation.lazy.LazyColumn
import androidx.compose.foundation.lazy.items
import androidx.compose.material3.a2ui.A2uiSurface

@Composable
fun BookingAssistantScreen(
    viewModel: BookingAssistantViewModel,
    modifier: Modifier = Modifier
) {
    val activeSurfaces by viewModel.activeSurfaces.collectAsState()
    LazyColumn(
        modifier = modifier.fillMaxWidth(),
        verticalArrangement = Arrangement.spacedBy(16.dp)
    ) {
        items(activeSurfaces) { surfaceModel ->
            Card(modifier = Modifier.fillMaxWidth()) {
                A2uiSurface(
                    surfaceModel = surfaceModel,
                    modifier = Modifier.fillMaxWidth().wrapContentHeight()
                )
            }
        }
    }
}

You will now see several UI surfaces generated by our agent running in the backend:

Check out the full source code for Jetpacker on GitHub, and watch the video Build Intelligent Android apps with Google’s AI to learn more about how to integrate agentic workflows directly into your app.

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All code snippets in this blog post follow the following copyright notice:

Copyright 2026 Google LLC.
SPDX-License-Identifier: Apache-2.0