【安全加密】实时风控：毫秒级的风险决策链

---实时风控：规则的快速评估
function RiskEngine.evaluate(uid, action)
    -- 先查缓存：短窗口内不重复评估
    local cached = RiskCache.get(uid, action)
    if cached ~= nil then return cached end
    -- 规则链按优先级依次评估
    for _, rule in ipairs(RiskEngine.rules) do
        local hit = rule.check(uid, action)
        if hit then
            RiskCache.set(uid, action, rule.result)
            return rule.result
        end
    end
    RiskCache.set(uid, action, 'pass')
    return 'pass'
end

---决策链的降级：规则引擎异常时的兜底
function RiskEngine.safeEvaluate(uid, action)
    local ok, result = pcall(RiskEngine.evaluate, uid, action)
    if not ok then
        -- 规则引擎异常：降级为仅黑名单
        Ops.alert('风控降级', uid)
        return Lists.check('black', uid) == false
    end
    return result
end