FastAPI spam filter.

# pip install fastapi uvicorn siftfy
import os
from fastapi import FastAPI
from pydantic import BaseModel, EmailStr
from siftfy import AsyncSiftfy

app = FastAPI()
client = AsyncSiftfy(api_key=os.environ["SIFTFY_KEY"], timeout=2.0)

class ContactSubmission(BaseModel):
    email: EmailStr
    message: str

@app.post("/contact")
async def contact(payload: ContactSubmission) -> dict[str, bool]:
    probability, ceiling = 0.0, None
    try:
        result = await client.predict(payload.message)
        probability, ceiling = result.spam_probability, result.max_confidence
    except Exception:
        # Fail open so a provider outage does not lose a real lead.
        probability = 0.0

    # Drop only ABOVE the ceiling the response reports. At the ceiling the score
    # is censored, so a fixed constant never fires on the model's own opinion.
    if ceiling is not None and probability > ceiling:
        return {"ok": True}
    if probability >= 0.50:
        await queue_for_review(payload.email, payload.message, probability)
    else:
        await deliver_to_inbox(payload.email, payload.message)
    return {"ok": True}