User Agent Generator (crawl4ai/user_agent_generator.py)

Generates random or online user‑agent strings and Sec‑CH‑UA client hints with fallback handling.

# Source: https://github.com/mperkins0155/crawl4ai-cobaltai | License: Apache-2.0
# Provided via justclaw.it.com; keep this notice with the code.
import random
from typing import Optional, Literal, List, Dict, Tuple
import re

from abc import ABC, abstractmethod
from fake_useragent import UserAgent
import requests
from lxml import html
import json
from typing import Union

class UAGen(ABC):
   @abstractmethod
   def generate(self, 
               browsers: Optional[List[str]] = None,
               os: Optional[Union[str, List[str]]] = None,
               min_version: float = 0.0,
               platforms: Optional[Union[str, List[str]]] = None,
               pct_threshold: Optional[float] = None,
               fallback: str = "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 Chrome/1

... (truncated -- full source via MCP)