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A2UI lets agents send declarative JSON UI specs that clients render with trusted component catalogues — integrate via the optional a2ui-agent-sdk package. 
from praisonaiagents import Agent

agent = Agent(
    name="assistant",
    instructions="Return declarative UI when a rich layout helps",
)
agent.start("Show a summary card with a primary action")
The user sends a chat message; the agent may respond with A2UI JSON for the client to render.
Install the optional extra: pip install praisonaiagents[a2ui]
For most web apps, structured output or AG-UI is simpler. Use A2UI when you need a portable UI spec across React, Flutter, Lit, and other renderers.

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Quick Start

1

Add A2UI to an agent

from praisonaiagents import Agent
from praisonaiagents.tools.a2ui_tools import send_a2ui_messages

agent = Agent(
    name="assistant",
    instructions="Return rich UI when helpful.",
    tools=[send_a2ui_messages],
)

agent.start("Show me a card with a summary button")
2

Build prompts with the facade API

from praisonaiagents import A2UI

prompt = A2UI.system_prompt(
    role_description="You are a helpful assistant that returns rich UI.",
    ui_description="Use cards and buttons from the basic catalog.",
)

part = A2UI.create_part({
    "createSurface": {"surfaceId": "main", "catalogId": "basic"},
})

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Generative UI Flow

  1. get_schema_manager() — load JSON schemas and catalog
  2. generate_a2ui_system_prompt() — inject schema into instructions
  3. Agent returns A2UI JSON via tool or structured output
  4. parse_a2ui_response() — validate and split text vs UI parts
  5. External renderer draws the UI

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Tool Input Shapes

send_a2ui_messages accepts:
InputAccepted
List of message dictsYes
JSON string of a listYes
{"messages": [...]} dictYes
Single message dictYes (wrapped in a list)

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Best Practices

Generative UI covers most CopilotKit and structured-output cases with less setup.
Catch schema errors server-side before the renderer receives invalid JSON.
Wrap payloads with create_a2ui_part() for application/json+a2ui compatibility.

Generative UI

Tiered UI options overview

Integrate A2UI Frontend

Connect any UI framework