app.py

import os
import gradio as gr
import anthropic

client = anthropic.Anthropic(api_key=os.environ.get("ANTHROPIC_API_KEY"))

SYSTEM_PROMPT = """You are a helpful, friendly, and knowledgeable AI assistant. 
You answer questions clearly and concisely, and you're always eager to help."""

def chat(message, history):
    """Send message to Claude and stream the response."""
    messages = []
    for user_msg, assistant_msg in history:
        messages.append({"role": "user", "content": user_msg})
        messages.append({"role": "assistant", "content": assistant_msg})
    messages.append({"role": "user", "content": message})

    response_text = ""
    with client.messages.stream(
        model="claude-sonnet-4-6",
        max_tokens=1024,
        system=SYSTEM_PROMPT,
        messages=messages,
    ) as stream:
        for text in stream.text_stream:
            response_text += text
            yield response_text

# ── UI ────────────────────────────────────────────────────────────────────────
with gr.Blocks(
    title="AI Chatbot",
    theme=gr.themes.Soft(primary_hue="violet"),
    css="""
        #chatbot { height: 520px; }
        footer { display: none !important; }
    """,
) as demo:
    gr.Markdown(
        """
        # 🤖 AI Chatbot
        Powered by Claude — ask me anything!
        """
    )

    chatbot = gr.Chatbot(
        elem_id="chatbot",
        bubble_full_width=False,
        show_label=False,
        avatar_images=(None, "https://www.anthropic.com/favicon.ico"),
    )

    with gr.Row():
        msg = gr.Textbox(
            placeholder="Type your message here…",
            show_label=False,
            scale=9,
            container=False,
        )
        send_btn = gr.Button("Send", variant="primary", scale=1)

    clear_btn = gr.ClearButton([msg, chatbot], value="🗑️ Clear Chat")

    def user_submit(message, history):
        return "", history + [[message, None]]

    def bot_respond(history):
        user_message = history[-1][0]
        prior_history = history[:-1]
        history[-1][1] = ""
        for chunk in chat(user_message, prior_history):
            history[-1][1] = chunk
            yield history

    msg.submit(user_submit, [msg, chatbot], [msg, chatbot], queue=False).then(
        bot_respond, chatbot, chatbot
    )
    send_btn.click(user_submit, [msg, chatbot], [msg, chatbot], queue=False).then(
        bot_respond, chatbot, chatbot
    )

if __name__ == "__main__":
    demo.queue()
    demo.launch()