A collapsible component that displays AI reasoning content, automatically opening during streaming and closing when finished.

The Reasoning component displays AI reasoning content, automatically opening during streaming and closing when finished.

See scripts/reasoning.tsx for this example.

npx ai-elements@latest add reasoning

Build a chatbot with reasoning using Deepseek R1 or other reasoning models.

Some models (like GPT with high reasoning effort) return multiple reasoning parts instead of a single streaming block. The example below consolidates all reasoning parts into a single component to avoid displaying multiple "Thinking..." indicators.

Add the following component to your frontend:

Create val
"use client";

import {
  Reasoning,
  ReasoningContent,
  ReasoningTrigger,
} from "@/components/ai-elements/reasoning";
import {
  Conversation,
  ConversationContent,
  ConversationScrollButton,
} from "@/components/ai-elements/conversation";
import {
  PromptInput,
  PromptInputSubmit,
  PromptInputTextarea,
} from "@/components/ai-elements/prompt-input";
import { Spinner } from "@/components/ui/spinner";
import {
  Message,
  MessageContent,
  MessageResponse,
} from "@/components/ai-elements/message";
import { useState } from "react";
import { useChat } from "@ai-sdk/react";
import type { UIMessage } from "ai";

const MessageParts = ({
  message,
  isLastMessage,
  isStreaming,
}: {
  message: UIMessage;
  isLastMessage: boolean;
  isStreaming: boolean;
}) => {
  // Consolidate all reasoning parts into one block
  const reasoningParts = message.parts.filter(
    (part) => part.type === "reasoning",
  );
  const reasoningText = reasoningParts.map((part) => part.text).join("\n\n");
  const hasReasoning = reasoningParts.length > 0;

  // Check if reasoning is still streaming (last part is reasoning on last message)
  const lastPart = message.parts.at(-1);
  const isReasoningStreaming = isLastMessage && isStreaming &&
    lastPart?.type === "reasoning";

  return (
    <>
      {hasReasoning && (
        <Reasoning className="w-full" isStreaming={isReasoningStreaming}>
          <ReasoningTrigger />
          <ReasoningContent>{reasoningText}</ReasoningContent>
        </Reasoning>
      )}
      {message.parts.map((part, i) => {
        if (part.type === "text") {
          return (
            <MessageResponse key={`${message.id}-${i}`}>
              {part.text}
            </MessageResponse>
          );
        }
        return null;
      })}
    </>
  );
};

const ReasoningDemo = () => {
  const [input, setInput] = useState("");

  const { messages, sendMessage, status } = useChat();

  const handleSubmit = (e: React.FormEvent) => {
    e.preventDefault();
    sendMessage({ text: input });
    setInput("");
  };

  const isStreaming = status === "streaming";

  return (
    <div className="max-w-4xl mx-auto p-6 relative size-full rounded-lg border h-[600px]">
      <div className="flex flex-col h-full">
        <Conversation>
          <ConversationContent>
            {messages.map((message, index) => (
              <Message from={message.role} key={message.id}>
                <MessageContent>
                  <MessageParts
                    message={message}
                    isLastMessage={index === messages.length - 1}
                    isStreaming={isStreaming}
                  />
                </MessageContent>
              </Message>
            ))}
            {status === "submitted" && <Spinner />}
          </ConversationContent>
          <ConversationScrollButton />
        </Conversation>

        <PromptInput
          onSubmit={handleSubmit}
          className="mt-4 w-full max-w-2xl mx-auto relative"
        >
          <PromptInputTextarea
            value={input}
            placeholder="Say something..."
            onChange={(e) => setInput(e.currentTarget.value)}
            className="pr-12"
          />
          <PromptInputSubmit
            status={isStreaming ? "streaming" : "ready"}
            disabled={!input.trim()}
            className="absolute bottom-1 right-1"
          />
        </PromptInput>
      </div>
    </div>
  );
};

export default ReasoningDemo;

Add the following route to your backend:

Create val
import { convertToModelMessages, streamText, UIMessage } from "ai";

// Allow streaming responses up to 30 seconds
export const maxDuration = 30;

export async function POST(req: Request) {
  const { model, messages }: { messages: UIMessage[]; model: string } =
    await req.json();

  const result = streamText({
    model: "deepseek/deepseek-r1",
    messages: await convertToModelMessages(messages),
  });

  return result.toUIMessageStreamResponse({
    sendReasoning: true,
  });
}

Use the Reasoning component when your model outputs thinking content as a single block or continuous stream (Deepseek R1, Claude with extended thinking, etc.).

If your model outputs discrete, labeled steps (search queries, tool calls, distinct thought stages), consider using the Chain of Thought component instead for a more structured visual representation.

• Automatically opens when streaming content and closes when finished
• Manual toggle control for user interaction
• Smooth animations and transitions powered by Radix UI
• Visual streaming indicator with pulsing animation
• Composable architecture with separate trigger and content components
• Built with accessibility in mind including keyboard navigation
• Responsive design that works across different screen sizes
• Seamlessly integrates with both light and dark themes
• Built on top of shadcn/ui Collapsible primitives
• TypeScript support with proper type definitions

Access the reasoning context from child components.

Create val
const { isStreaming, isOpen, setIsOpen, duration } = useReasoning();

Returns: