Static_path/1 not using :cache_static_manifest_latest

Hi. I can’t get static_path/1 to use :cache_static_manifest_latest.

Web.Endpoint.config(:cache_static_manifest_latest)["latest"]["css/app.css"]
"css/app-5333df5cf02622c70a2544da7d0c81c8.css"

Web.Endpoint.static_path("/css/app.css")
"/css/app.css"

Web.Endpoint.static_path("css/app.css")
** (ArgumentError) expected a path starting with a single / but got "css/app.css"

I’m not sure it matters, but here’s how I’m loading :cache_static_manifest_latest.

config :web, Web.Endpoint,
  ...
  cache_static_manifest_latest: true
  ...


defmodule Web.Endpoint do
  use Phoenix.Endpoint, otp_app: :web

  def init(_supervisor, config) do
    config = case config[:cache_static_manifest_latest] do
      true -> Keyword.put(config, :cache_static_manifest_latest, fetch_cache_manifest())
      _ -> config
    end
    {:ok, config}
  end

  defp fetch_cache_manifest do
    # loads from S3
  end

  ...

end

Thanks for the help.