Hi there 👋 is there a documentation somewhere about which artifacts are stored in remote cache? esp. for java and python?

There is no such documentation. For python, its only test results, for the jvm jar resolution, compile results and test results. If you

./pants clean-all

and then

./pants <operation>

you can looks for lines that say 'Using cached artifacts for X targets' to see which steps use the remote cache. For example here you see zinc compilation of jvm code hitting the cache for 19 targets:

...
09:57:46 00:05   [compile]
09:57:46 00:05     [compile-jvm-prep-command]
09:57:46 00:05       [jvm_prep_command]
09:57:46 00:05     [compile-prep-command]
09:57:46 00:05     [compile]
09:57:46 00:05     [rsc]
09:57:46 00:05     [zinc]
09:57:46 00:05       [cache]...................
                   Using cached artifacts for 19 targets.
09:57:46 00:05     [javac]
09:57:46 00:05     [go]
...

Thank you 🙂