Implement rate limiting and error handling in FastAPI application; update requirements.txt to include 'limits'

app.py

@@ -14,14 +14,34 @@ export SERPER_API_KEY="YOUR‑KEY‑HERE"
 import os, json, asyncio, httpx, trafilatura, gradio as gr
 from dateutil import parser as dateparser
 from pathlib import Path
+from limits import RateLimitItem, parse
+from limits.aio.storage import MemoryStorage
+from limits.aio.strategies import MovingWindowRateLimiter
+from fastapi import FastAPI, Request, HTTPException
+from fastapi.responses import JSONResponse
 
 SERPER_API_KEY = os.getenv("SERPER_API_KEY")
 SERPER_ENDPOINT = "https://google.serper.dev/news"
 HEADERS = {"X-API-KEY": SERPER_API_KEY, "Content-Type": "application/json"}
 
+# Rate limiting
+app = FastAPI()
+storage = MemoryStorage()
+limiter = MovingWindowRateLimiter(storage)
+rate_limit = parse("200/hour")
+
+
+@app.exception_handler(HTTPException)
+async def http_exception_handler(request: Request, exc: HTTPException):
+    return JSONResponse(status_code=exc.status_code, content={"message": exc.detail})
+
 
 ### 1 ─ Serper call -------------------------------------------------------------
+@app.post("/serper-news")
 async def get_serper_news(query: str, num: int = 4) -> list[dict]:
+    if not await limiter.hit(rate_limit, "global"):
+        raise HTTPException(status_code=429, detail="Too Many Requests")
+
     payload = {"q": query, "type": "news", "num": num, "page": 1}
     async with httpx.AsyncClient(timeout=15) as client:
         resp = await client.post(SERPER_ENDPOINT, headers=HEADERS, json=payload)
@@ -30,7 +50,7 @@ async def get_serper_news(query: str, num: int = 4) -> list[dict]:
 
 
 ### 2 ─ Concurrent HTML downloads ----------------------------------------------
-async def fetch_html_many(urls: list[str]) -> list[str]:
+async def fetch_html_many(urls: list[str]) -> list[dict]:
     async with httpx.AsyncClient(timeout=20, follow_redirects=True) as client:
         tasks = [client.get(u) for u in urls]
         responses = await asyncio.gather(*tasks, return_exceptions=True)

requirements.txt

@@ -1,4 +1,5 @@
 gradio
 httpx
 trafilatura
-python-dateutil
+python-dateutil
+limits