Update README.md

README.md

@@ -6,15 +6,61 @@ colorTo: red
 sdk: docker
 app_port: 8501
 tags:
-- streamlit
+  - streamlit
+  - fastapi
+  - openrouter
 pinned: false
-short_description: Streamlit template space
+short_description: Streamlit + FastAPI chat UI for OpenRouter
 license: mit
 ---
 
-# Welcome to Streamlit!
+# ChatLLM — Streamlit + FastAPI on Hugging Face Spaces
 
-Edit `/src/streamlit_app.py` to customize this app to your heart's desire. :heart:
+A lightweight chat UI powered by Streamlit (frontend) and FastAPI (backend) that proxies requests to OpenRouter. Runs as a single Docker Space with both services in one container.
 
-If you have any questions, checkout our [documentation](https://docs.streamlit.io) and [community
-forums](https://discuss.streamlit.io).
+Main files
+- `src/app.py` — Streamlit frontend
+- `src/server.py` — FastAPI backend
+- `requirements.txt` — Python deps
+- `Dockerfile` — Multi-service (Streamlit + FastAPI) using s6-overlay
+
+Features
+- Client-side API key entry (never stored on server)
+- Optional server-side fallback API key via Space secret
+- System prompt editor and model selector
+- Health checks for frontend and backend
+
+Deploy on Hugging Face Spaces (Docker)
+1) Set Space to SDK: Docker.
+2) In Settings → Variables and secrets, add:
+   - `BACKEND_URL` = `http://localhost:8000/chat`
+   - `OPENROUTER_API_KEY` = `or-xxxxxxxx` (optional; acts as fallback)
+3) Push your repo with `Dockerfile`, `requirements.txt`, and `src/` folder.
+4) Open the Space URL. In the app, expand Settings and paste your key if you didn’t set a server fallback.
+
+Local development (optional)
+- Build and run:
+  - `docker build -t chatllm .`
+  - `docker run --rm -p 8501:8501 -p 8000:8000 -e BACKEND_URL=http://localhost:8000/chat chatllm`
+- Visit `http://localhost:8501`
+
+Environment variables
+- `BACKEND_URL` — Where the frontend calls the backend. For single-container Spaces, use `http://localhost:8000/chat`.
+- `OPENROUTER_API_KEY` — Optional server fallback key. If not set, users enter their own key in the UI.
+
+Security notes
+- Never commit your API key to the repo.
+- Keys entered in the UI are kept in the browser session and sent only as an `Authorization` header per request.
+
+Troubleshooting
+- App loads but chat doesn’t respond:
+  - Check Space logs. Ensure backend started (Uvicorn on port 8000).
+  - Verify `BACKEND_URL` is set to `http://localhost:8000/chat`.
+- “Missing OpenRouter API key”:
+  - Paste your key in the UI Settings, or set `OPENROUTER_API_KEY` as a Space secret.
+- Test endpoints inside container:
+  - `curl http://localhost:8501/_stcore/health`
+  - `curl http://localhost:8000/docs`
+
+License
+- MIT