Fix Streamable HTTP Accept header quality-factor handling #3154

from starlette.requests import Request

def check_accept_headers(request: Request) -> tuple[bool, bool]:
    accept_header = request.headers.get("accept", "")
    accept_types = [media_type.strip().split(";")[0].strip().lower() for media_type in accept_header.split(",")]

    has_wildcard = "*/*" in accept_types
    has_json = has_wildcard or any(t in ("application/json", "application/*") for t in accept_types)
    has_sse = has_wildcard or any(t in ("text/event-stream", "text/*") for t in accept_types)

    return has_json, has_sse

# Example: client explicitly rejects JSON
request = Request({"type": "http", "method": "GET", "headers": [(b"accept", b"application/json;q=0, text/event-stream;q=1.0")]})

print(check_accept_headers(request))
# -> (True, True)