Okay, let's dive into Gradio's capability to create a "website widget" or, more accurately, how to use Gradio's backend API with a custom JavaScript front-end, potentially embedded in any website.

This is primarily achieved using the @gradio/client JavaScript library.

How it Works (APIs):

Gradio Backend Server: When you run demo.launch() in your app.py, Gradio starts a web server (usually based on FastAPI). This server does two things:
Serves the standard Gradio web UI you've been using.
Exposes API endpoints that allow programmatic interaction with your Gradio app's functions.
API Endpoint: For a function like your chat function, Gradio typically creates an endpoint (often under /run/predict or similar, though the client library handles the exact path). This endpoint accepts HTTP requests (usually POST) containing the input data (like message, history, hotel_id).
@gradio/client (JavaScript): This is a library you use in your custom front-end code (HTML/JavaScript running in the user's browser or on your web server).
You initialize the client, pointing it to the URL where your Gradio app (app.py) is running (e.g., your Hugging Face Space URL or http://127.0.0.1:7860 if running locally).
Your JavaScript code gathers user input (from your custom HTML input fields).
You use the @gradio/client's functions (like predict) to send the input data to the Gradio backend's API endpoint.
The client library handles making the HTTP request to the Gradio server.
Backend Processing: The Gradio server receives the API request, extracts the data, and calls your Python chat function with the provided arguments. Your Python code runs, loads documents, prepares prompts, calls the LLM, and gets a response.
API Response: The Gradio server packages the return value(s) from your chat function (the updated ui_history and the empty string) into an HTTP response and sends it back to the @gradio/client.
Frontend Update: Your JavaScript code receives the response via the client library and uses it to update your custom HTML UI (e.g., display the new assistant message in your custom chat display).
Key Point: You are not replacing the Gradio backend (app.py). You are replacing the Gradio frontend UI with your own custom HTML, CSS, and JavaScript, which then communicates with the existing Gradio backend API using the @gradio/client library.

Gains vs. Losses:

What You Gain:

Complete UI Control: You have 100% control over the appearance, layout, and behavior of the chat interface. You can match your website's branding perfectly.
Seamless Integration: Embed the chat functionality directly within any existing webpage or web application without using an <iframe>.
Custom Interactions: Implement unique UI features or workflows not possible with standard Gradio components.
Decoupling: Clear separation between your Python backend logic and the frontend presentation layer.
What You Lose:

Gradio's Pre-built UI: You lose the convenience of the gr.Chatbot, gr.Textbox, gr.Dropdown, etc. You have to build the entire chat interface (displaying messages, handling input, scrolling) yourself using HTML, CSS, and JavaScript.
Simplicity: Requires frontend development skills (HTML/CSS/JS) and understanding how to use the @gradio/client library. It's significantly more complex than just writing the Python Gradio app.
Built-in Features: You lose Gradio's themes, automatic layout, and potentially some interactive features unless you reimplement them.
State Management: Your custom JavaScript frontend is responsible for managing the chat history state between interactions.
Local vs. Hosted Implementation:

Yes, you can absolutely implement this both locally and hosted. The core requirement is that your custom frontend (the HTML/JS using @gradio/client) can make network requests to the running Gradio backend (app.py).

Hosted (e.g., using HF Space):

Your app.py runs on Hugging Face Spaces, accessible via its public URL (e.g., https://your-username-your-space-name.hf.space).
Your custom website/widget (HTML/JS) can be hosted anywhere (GitHub Pages, Netlify, Vercel, your own server, etc.).
In your JavaScript, you initialize @gradio/client pointing to the public HF Space URL: const client = await connect("your-username-your-space-name"); or const client = await connect("https://your-username-your-space-name.hf.space/");.
The user's browser running your website's JS makes requests directly to the HF Space backend.
Local Development:

Run app.py: Start your Gradio backend locally: python app.py. It will typically run on http://127.0.0.1:7860.
Create Frontend Files: Create separate index.html, style.css, script.js files for your custom chat UI.
Configure JS Client: In your script.js, initialize the client pointing to your local Gradio server: const client = await connect("http://127.0.0.1:7860");.
Serve Frontend: You need a way for your browser to access the HTML/CSS/JS files. Options:
Simple Local Server (Recommended for Dev): Navigate to your frontend project directory in WSL/terminal and run python -m http.server 8000 (or any other available port). Then open http://localhost:8000 in your browser. This is very easy and requires no extra frameworks. VS Code's "Live Server" extension is another great option.
Flask/FastAPI (in WSL): Create a separate, minimal Flask or FastAPI app in WSL. This app's only job is to serve your static index.html, style.css, script.js files. Your JS still connects to the Gradio app running on port 7860. This is more structured if you plan to build a larger web app later.
XAMPP: You could use XAMPP, placing your frontend files in htdocs. Start Apache and access via http://localhost. Your JS would still connect to the Gradio app on port 7860. This adds unnecessary PHP/MySQL overhead unless you specifically need them for other reasons.
Recommendation for Local: Start with the Simple Local Server method (python -m http.server or VS Code Live Server). It's the quickest way to get your custom HTML/JS frontend running and talking to your local Gradio backend (app.py) without adding extra complexity initially.