i2y/castella/castella-agent-ui

from castella.agent import AgentChat
chat = AgentChat.from_a2a("http://localhost:8080")
chat.run()

uv sync --extra agent   # Agent UI + A2A + A2UI support

from castella.agent import AgentChat
# Connect to A2A agent
chat = AgentChat.from_a2a("http://localhost:8080")
chat.run()
# Or use custom handler function
chat = AgentChat(
    handler=lambda msg: f"Echo: {msg}",
    title="Echo Bot",
    system_message="Welcome! How can I help?",
)
chat.run()

AgentChat(
    a2a_client=None,           # A2AClient instance
    handler=None,              # Custom handler: (str) -> str
    title="Agent Chat",        # Window title
    placeholder="Type...",     # Input placeholder
    system_message=None,       # Initial system message
    show_agent_card=True,      # Show agent card for A2A
    width=700,                 # Window width
    height=550,                # Window height
)

# From A2A agent URL
chat = AgentChat.from_a2a("http://localhost:8080")
# From A2A client
from castella.a2a import A2AClient
client = A2AClient("http://localhost:8080")
chat = AgentChat.from_a2a(client)

from castella.agent import ChatContainer, ChatMessageData
from castella.core import ListState
messages = ListState([])
def on_send(text: str):
    messages.append(ChatMessageData(role="user", content=text))
    # Get response from agent...
    response = get_response(text)
    messages.append(ChatMessageData(role="assistant", content=response))
container = ChatContainer(
    messages,
    on_send=on_send,
    title="My Chat",
    placeholder="Type a message...",
)

from castella.agent import ChatMessage, ChatMessageData
msg = ChatMessageData(
    role="assistant",  # "user", "assistant", or "system"
    content="Hello! How can I help you today?",
)
widget = ChatMessage(msg)

from castella.agent import ChatInput
input_widget = ChatInput(
    placeholder="Type a message...",
    on_send=lambda text: print(f"Sent: {text}"),
)

from castella.agent import ChatView
from castella.core import ScrollState
scroll_state = ScrollState()
view = ChatView(messages, scroll_state=scroll_state)

from castella.agent import ChatMessageData, ToolCallData
msg = ChatMessageData(
    role="assistant",
    content="Let me check the weather for you.",
    tool_calls=[
        ToolCallData(
            id="call_1",
            name="get_weather",
            arguments={"location": "Tokyo"},
            result="Sunny, 22°C",
        )
    ],
)

from castella.agent import ToolCallView
tool = ToolCallView(
    name="get_weather",
    arguments={"location": "Tokyo"},
    result="Sunny, 22°C",
)

from castella.agent import ToolHistoryPanel
from castella.core import ListState
tool_calls = ListState([...])
panel = ToolHistoryPanel(tool_calls)

from castella.agent import AgentCardView
from castella.a2a import A2AClient
client = A2AClient("http://agent.example.com")
card_view = AgentCardView(
    client.agent_card,
    show_skills=True,
    compact=False,
)

from castella.agent import AgentListView
agent_list = AgentListView(
    agents=[client1.agent_card, client2.agent_card],
    on_select=lambda card: print(f"Selected: {card.name}"),
)

from castella.agent import MultiAgentChat
from castella.a2a import A2AClient
chat = MultiAgentChat({
    "weather": A2AClient("http://localhost:8081"),
    "travel": A2AClient("http://localhost:8082"),
    "restaurant": A2AClient("http://localhost:8083"),
})
chat.run()

from castella.agent import AgentHub
from castella.a2a import A2AClient
# Create hub
hub = AgentHub(title="Agent Hub")
# Add agents
hub.add_agent("http://localhost:8081")
hub.add_agent(A2AClient("http://localhost:8082"))
hub.run()

hub = AgentHub(agents=[
    A2AClient("http://agent1.example.com"),
    A2AClient("http://agent2.example.com"),
])

class ChatComponent(Component):
    def __init__(self):
        super().__init__()
        self._messages = ListState([])
        self._messages.attach(self)
        self._scroll_state = ScrollState()
        # DON'T attach scroll state
    def _send_message(self, text: str):
        # Add user message
        self._messages.append(ChatMessageData(role="user", content=text))
        # Get response...
        response = get_response(text)
        # Set scroll BEFORE adding response (so re-render picks it up)
        self._scroll_state.y = 999999
        self._messages.append(ChatMessageData(role="assistant", content=response))

class MyComponent(Component):
    def __init__(self):
        super().__init__()
        self._state = State(0)
        self._states_attached = False
        # DON'T attach here - App may not exist yet
    def view(self):
        # Attach lazily when view() is called
        if not self._states_attached:
            self._state.attach(self)
            self._states_attached = True
        return Text(str(self._state()))

msg = ChatMessageData(
    role="assistant",
    content="""
# Weather Report
**Tokyo**: Sunny, 22°C
| Day | High | Low |
|-----|------|-----|
| Mon | 24°C | 18°C |
| Tue | 22°C | 17°C |
""",
)