This is about all caches related to ResourceLoader:
* minification cache.
* any tracked timestamps (of on-disk files, or other objects).
* definition summaries.
* module versions (as included in the startup manifest).
* localstorage cache (cache key should remain the same).
Known issues that prevent this are listed below. These currently cause web clients to have to re-download modules that are effectively unchanged, but are needlessly being invalidated when upgrading a wiki to a newer wmf branch:
* [ ] File modules include `localBasePath` in their definition summary, which includes the absolute path to `$IP`, which for wmf-production includes the mediawiki deployment tag (e.g. `1.26wmf4`).
* [ ] File modules track file timestamps. Git does not save file meta data, so when creating a new clone of mediawiki, all timestamps start with "now". This could be mitigated by using hashing of file contents instead of timestamps. Another workaround would have some kind of persistent clone because when running git-pull or git-checkout, file that are unchanged keep their timestamp.
* [ ] ..