We need to be able to (a) distinguish between cacheable and uncacheable responses in Lua, and (b) know the object lifetime as calculated by ATS. See for instance T250815. The proper methods are currently not implemented upstream, so we need to add them. This task tracks the progress of implementing the changes, getting them merged upstream, and backported to our packages.
I have opened https://github.com/apache/trafficserver/pull/6726 which takes care of (a) and https://github.com/apache/trafficserver/pull/6730 taking care of part of (b), namely adding the method to the trafficserver API. The same method will have to be exposed via tslua too.