feat: add FastAPI real-time chat template

fastapi/README.md

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+# FastAPI Real-time Chat Template
+
+A real-time chat application built with FastAPI and WebSockets.
+
+## Features
+- Real-time messaging via WebSockets
+- Simple username/password authentication
+- Join/leave notifications
+- Broadcast messaging
+- Clean, responsive UI
+
+## Quick Start
+
+1. **Install dependencies**
+```bash
+pip install -r requirements.txt
+```
+
+2. **Run the server**
+```bash
+uvicorn main:app --host 0.0.0.0 --port 8080 --reload
+```
+
+3. **Open in browser**
+Navigate to `http://localhost:8080`
+
+## Test Users
+- Username: `alice`, Password: `password123`
+- Username: `bob`, Password: `securepass456`
+
+## API Endpoints
+- `GET /` - Chat web interface
+- `POST /login` - User login
+- `WS /ws/{username}` - WebSocket chat connection
+
+## Structure
+```
+fastapi/
+├── main.py           # FastAPI application
+├── public/
+│   └── index.html    # Chat frontend
+├── requirements.txt  # Python dependencies
+├── ci.yml           # Codesphere CI pipeline
+├── start.sh         # Startup script
+└── README.md        # This file
+```

fastapi/ci.yml

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+prepare:
+  steps:
+  - name: "Install dependencies"
+    command: "pip install -r requirements.txt"
+
+test:
+  steps:
+  - name: "Run tests"
+    command: "python -m pytest tests/ -v"
+
+run:
+  steps:
+  - name: "Start FastAPI server"
+    command: "uvicorn main:app --host 0.0.0.0 --port 8080"

fastapi/main.py

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+from fastapi import FastAPI, WebSocket, WebSocketDisconnect, Depends, HTTPException, status
+from fastapi.security import HTTPBasic, HTTPBasicCredentials
+from fastapi.responses import HTMLResponse
+import json
+import asyncio
+from typing import Set, Dict
+from datetime import datetime
+
+app = FastAPI(title="FastAPI Chat", version="1.0.0")
+security = HTTPBasic()
+
+# Simple in-memory user store (for demo purposes)
+USERS = {
+    "alice": "password123",
+    "bob": "securepass456"
+}
+
+# WebSocket connection manager
+class ConnectionManager:
+    def __init__(self):
+        self.active_connections: Dict[str, WebSocket] = {}
+
+    async def connect(self, username: str, websocket: WebSocket):
+        await websocket.accept()
+        self.active_connections[username] = websocket
+        await self.broadcast(f"{username} joined the chat!", "system")
+
+    def disconnect(self, username: str):
+        if username in self.active_connections:
+            del self.active_connections[username]
+
+    async def broadcast(self, message: str, sender: str = "system"):
+        disconnected = []
+        for username, ws in self.active_connections.items():
+            try:
+                await ws.send_json({
+                    "sender": sender,
+                    "message": message,
+                    "timestamp": datetime.now().isoformat()
+                })
+            except:
+                disconnected.append(username)
+        for username in disconnected:
+            self.disconnect(username)
+
+manager = ConnectionManager()
+
+@app.get("/")
+async def get():
+    with open("public/index.html", "r") as f:
+        return HTMLResponse(f.read())
+
+@app.post("/login")
+async def login(credentials: HTTPBasicCredentials = Depends(security)):
+    username = credentials.username
+    password = credentials.password
+
+    if username in USERS and USERS[username] == password:
+        return {"username": username, "status": "logged_in"}
+
+    raise HTTPException(
+        status_code=status.HTTP_401_UNAUTHORIZED,
+        detail="Invalid credentials",
+    )
+
+@app.websocket("/ws/{username}")
+async def websocket_endpoint(websocket: WebSocket, username: str):
+    await manager.connect(username, websocket)
+    try:
+        while True:
+            data = await websocket.receive_text()
+            message_data = json.loads(data)
+            if message_data.get("type") == "message":
+                await manager.broadcast(message_data["content"], username)
+    except WebSocketDisconnect:
+        manager.disconnect(username)
+        await manager.broadcast(f"{username} left the chat!", "system")

fastapi/metadata.json

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+{
+  "Workspace": "free",
+  "Links": {
+    "Python": "https://codesphere.com/articles/python",
+    "FastAPI": "https://fastapi.tiangolo.com/"
+  },
+  "Categories": [
+    "Framework"
+  ],
+  "Contributors": [
+    "ydd039"
+  ],
+  "Title": "FastAPI - Real-time Chat App"
+}

fastapi/public/index.html

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+<!DOCTYPE html>
+<html lang="en">
+<head>
+    <meta charset="UTF-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1.0">
+    <title>FastAPI Chat</title>
+    <style>
+        * { margin: 0; padding: 0; box-sizing: border-box; }
+        body { font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif; background: linear-gradient(135deg, #667eea 0%, #764ba2 100%); height: 100vh; display: flex; align-items: center; justify-content: center; }
+        .container { background: white; border-radius: 16px; box-shadow: 0 20px 60px rgba(0,0,0,0.3); width: 450px; max-width: 90vw; overflow: hidden; }
+        .header { background: #667eea; color: white; padding: 20px; text-align: center; }
+        .header h1 { font-size: 24px; margin-bottom: 5px; }
+        .header p { opacity: 0.8; font-size: 14px; }
+        .login-form { padding: 20px; display: flex; flex-direction: column; gap: 12px; }
+        .login-form input { padding: 12px; border: 2px solid #e0e0e0; border-radius: 8px; font-size: 14px; transition: border-color 0.3s; }
+        .login-form input:focus { outline: none; border-color: #667eea; }
+        .login-form button { background: #667eea; color: white; border: none; padding: 12px; border-radius: 8px; font-size: 16px; cursor: pointer; transition: background 0.3s; }
+        .login-form button:hover { background: #5a6fd6; }
+        .login-form .error { color: #e74c3c; font-size: 13px; text-align: center; }
+        .chat { display: none; flex-direction: column; padding: 0; }
+        .messages { height: 350px; overflow-y: auto; padding: 20px; background: #f8f9fa; display: flex; flex-direction: column; gap: 10px; }
+        .message { padding: 10px 14px; border-radius: 12px; max-width: 75%; word-wrap: break-word; }
+        .message.user { background: #667eea; color: white; align-self: flex-end; }
+        .message.other { background: white; color: #333; align-self: flex-start; box-shadow: 0 1px 3px rgba(0,0,0,0.1); }
+        .message.system { background: transparent; color: #999; align-self: center; font-size: 12px; font-style: italic; }
+        .message .time { font-size: 11px; opacity: 0.7; margin-top: 4px; }
+        .input-area { display: flex; padding: 15px; gap: 10px; border-top: 1px solid #e0e0e0; }
+        .input-area input { flex: 1; padding: 12px; border: 2px solid #e0e0e0; border-radius: 8px; font-size: 14px; }
+        .input-area input:focus { outline: none; border-color: #667eea; }
+        .input-area button { background: #667eea; color: white; border: none; padding: 12px 20px; border-radius: 8px; cursor: pointer; }
+        .user-info { display: none; padding: 10px 20px; background: #f0f0f0; font-size: 13px; color: #666; justify-content: space-between; align-items: center; }
+        .user-info .logout { color: #e74c3c; cursor: pointer; text-decoration: underline; }
+    </style>
+</head>
+<body>
+    <div class="container">
+        <div class="header">
+            <h1>💬 FastAPI Chat</h1>
+            <p>Real-time messaging with WebSockets</p>
+        </div>
+
+        <div class="login-form" id="loginForm">
+            <h3 style="text-align:center;margin-bottom:5px;">Sign In</h3>
+            <input type="text" id="username" placeholder="Username" value="alice">
+            <input type="password" id="password" placeholder="Password" value="password123">
+            <div class="error" id="loginError"></div>
+            <button onclick="login()">Join Chat</button>
+        </div>
+
+        <div class="user-info" id="userInfo">
+            <span>Logged in as: <strong id="displayName"></strong></span>
+            <span class="logout" onclick="logout()">Logout</span>
+        </div>
+
+        <div class="chat" id="chatArea">
+            <div class="messages" id="messages"></div>
+            <div class="input-area">
+                <input type="text" id="messageInput" placeholder="Type a message..." onkeypress="if(event.key==='Enter') sendMessage()">
+                <button onclick="sendMessage()">Send</button>
+            </div>
+        </div>
+    </div>
+
+    <script>
+        let ws = null;
+        let currentUser = null;
+
+        async function login() {
+            const username = document.getElementById('username').value;
+            const password = document.getElementById('password').value;
+
+            const res = await fetch('/login', {
+                method: 'POST',
+                headers: {
+                    'Authorization': 'Basic ' + btoa(username + ':' + password)
+                }
+            });
+
+            if (res.ok) {
+                currentUser = username;
+                document.getElementById('loginForm').style.display = 'none';
+                document.getElementById('userInfo').style.display = 'flex';
+                document.getElementById('displayName').textContent = username;
+                document.getElementById('chatArea').style.display = 'flex';
+                connectWebSocket(username);
+            } else {
+                document.getElementById('loginError').textContent = 'Invalid credentials';
+            }
+        }
+
+        function connectWebSocket(username) {
+            const protocol = window.location.protocol === 'https:' ? 'wss:' : 'ws:';
+            const host = window.location.host;
+            ws = new WebSocket(`${protocol}//${host}/ws/${username}`);
+
+            ws.onmessage = function(event) {
+                const data = JSON.parse(event.data);
+                addMessage(data.sender, data.message, data.sender === currentUser ? 'user' : (data.sender === 'system' ? 'system' : 'other'));
+            };
+
+            ws.onclose = function() {
+                addMessage('system', 'Disconnected. Refresh to reconnect.', 'system');
+            };
+        }
+
+        function sendMessage() {
+            const input = document.getElementById('messageInput');
+            const text = input.value.trim();
+            if (text && ws && ws.readyState === WebSocket.OPEN) {
+                ws.send(JSON.stringify({type: 'message', content: text}));
+                input.value = '';
+            }
+        }
+
+        function addMessage(sender, text, type) {
+            const messages = document.getElementById('messages');
+            const div = document.createElement('div');
+            div.className = 'message ' + type;
+            div.innerHTML = sender !== 'system' ? `<strong>${sender}</strong><br>${text}` : text;
+            messages.appendChild(div);
+            messages.scrollTop = messages.scrollHeight;
+        }
+
+        function logout() {
+            if (ws) ws.close();
+            currentUser = null;
+            document.getElementById('loginForm').style.display = 'flex';
+            document.getElementById('userInfo').style.display = 'none';
+            document.getElementById('chatArea').style.display = 'none';
+            document.getElementById('messages').innerHTML = '';
+            document.getElementById('loginError').textContent = '';
+        }
+    </script>
+</body>
+</html>

fastapi/requirements.txt

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+fastapi==0.115.6
+uvicorn[standard]==0.34.0
+websockets>=12.0
+python-jose[cryptography]==3.3.0
+passlib[bcrypt]==1.7.4
+pydantic==2.10.3
+python-multipart==0.0.17

fastapi/start.sh

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+#!/bin/bash
+# For development:
+uvicorn main:app --host 0.0.0.0 --port 8080 --reload
+
+# For production:
+# uvicorn main:app --host 0.0.0.0 --port 8080 --workers 4

fastapi/tests/test_chat.py

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+from fastapi.testclient import TestClient
+from main import app
+
+client = TestClient(app)
+
+def test_root_endpoint():
+    response = client.get("/")
+    assert response.status_code == 200
+    assert "text/html" in response.headers["content-type"]
+
+def test_login_valid():
+    from requests.auth import HTTPBasicAuth
+    # Test with valid credentials
+    response = client.post("/login", auth=("alice", "password123"))
+    assert response.status_code == 200
+    assert response.json()["username"] == "alice"
+
+def test_login_invalid():
+    response = client.post("/login", auth=("alice", "wrongpass"))
+    assert response.status_code == 401