Funnel

uploaded = 后端 remove 成功(api_logs type=remove, status=success)。

result_viewed = 结果图渲染到可见 canvas(每图去重一次)。uploaded ≈ result_viewed → 展示链路通。

downloaded = 用户点了下载(每次计数)。uploaded ≫ downloaded 是正常落差(一次性需求)。

⚠ 只有 uploaded ≫ result_viewed 才说明"看不到结果"是真问题。