Slots (Subcomponents)

What is this?

Every CopilotKit chat component is built from composable slots — named sub-components that you can override individually. The slot system gives you three levels of customization without needing to rebuild the entire UI:

1. Tailwind classes — pass a string to add/override CSS classes
2. Props override — pass an object to override specific props on the default component
3. Custom component — pass your own React component to fully replace a slot

Slots are recursive — you can drill into nested sub-components at any depth.

What it looks like in code

The chat-slots cell above overrides three slots on a single <CopilotChat> — the welcome screen, the assistant message card, and the input's disclaimer. Each slot is just a prop; the demo extracts them into locals so the override points are easy to see.

Welcome screen slot

The welcomeScreen prop replaces the empty-state view shown before the first message is sent. The demo swaps in a gradient card that still renders the default input and suggestions:

Assistant message slot

Drill into messageView={{ assistantMessage: ... }} to wrap every assistant response. The cell wraps the default component with a tinted card and a small "slot" badge so you can see the override is active during the message flow:

Disclaimer slot

The input={{ disclaimer: ... }} sub-slot lets you replace the small text shown below the input. The demo uses it to display a visibly tagged disclaimer so reviewers can tell the override is still in effect once the welcome screen is gone:

Tailwind Classes

The simplest way to customize a slot. Pass a Tailwind class string and it will be merged with the default component's classes.

import { CopilotChat } from "@copilotkit/react-core/v2";

export function Chat() {
  return (
    <CopilotChat
      messageView="bg-gray-50 dark:bg-gray-900 p-4"
      input="border-2 border-blue-400 rounded-xl"
    />
  );
}

Props Override

Pass an object to override specific props on the default component. This is useful for adding className, event handlers, data attributes, or any other prop the default component accepts.

<CopilotChat
  messageView={{
    className: "my-custom-messages",
    "data-testid": "message-view",
  }}
  input={{ autoFocus: true }}
/>

Custom Components

For full control, pass your own React component. It receives all the same props as the default component.

import { CopilotChat } from "@copilotkit/react-core/v2";

const CustomMessageView = ({ messages, isRunning }) => (
  <div className="space-y-4 p-6">
    {messages?.map((msg) => (
      <div key={msg.id} className={msg.role === "user" ? "text-right" : "text-left"}>
        {msg.content}
      </div>
    ))}
    {isRunning && <div className="animate-pulse">Thinking...</div>}
  </div>
);

export function Chat() {
  return <CopilotChat messageView={CustomMessageView} />;
}

Nested Slots (Drill-Down)

Slots are recursive. You can customize sub-components at any depth by nesting objects.

Two levels deep

Override the assistant message's toolbar within the message view:

<CopilotChat
  messageView={{
    assistantMessage: {
      toolbar: CustomToolbar,
      copyButton: CustomCopyButton,
    },
    userMessage: CustomUserMessage,
  }}
/>

Three levels deep

Override a specific button inside the assistant message toolbar:

<CopilotChat
  messageView={{
    assistantMessage: {
      copyButton: ({ onClick }) => (
        <button onClick={onClick}>Copy</button>
      ),
    },
  }}
/>

Labels

Customize any text string in the UI via the labels prop. This does not use the slot system — it's a separate convenience prop on CopilotChat, CopilotSidebar, and CopilotPopup.

<CopilotChat
  labels={{
    chatInputPlaceholder: "Ask your agent anything...",
    welcomeMessageText: "How can I help you today?",
    chatDisclaimerText: "AI responses may be inaccurate.",
  }}
/>

Available Slots

CopilotChat / CopilotSidebar / CopilotPopup

These are the root-level slot props available on all chat components:

CopilotSidebar and CopilotPopup also have: