* use post-cache transform instead of splitting the parser cache:
** ~~[[https://gerrit.wikimedia.org/r/#/c/399907/|399907 (core): Add 'unwrap' ParserOutput post-cache transform]]~~
** ~~[[https://gerrit.wikimedia.org/r/#/c/399909/|399909 (CiteThisPage): Use 'unwrap' post-cache transform instead of setWrapOutputClass( false )]]~~
** ~~[[https://gerrit.wikimedia.org/r/#/c/399910/|399910 (MobileFrontend): Use 'unwrap' post-cache transform instead of setWrapOutputClass( false ), when available]]~~
** ~~[[https://gerrit.wikimedia.org/r/#/c/399912/|399912 (TemplateStyles): Use 'unwrap' post-cache transform instead of setWrapOutputClass( false )]]~~
** ~~[[https://gerrit.wikimedia.org/r/#/c/399914/|399914 (Wikibase): Use 'unwrap' post-cache transform instead of setWrapOutputClass( false )]]~~
** [[https://gerrit.wikimedia.org/r/#/c/399908/|399908 (core): Remove wrapclass from parser cache key]]
* style deduplication:
** [[https://gerrit.wikimedia.org/r/#/c/394369/|394369 (TemplateStyles): Cache processed stylesheets during the parse]]
** [[https://gerrit.wikimedia.org/r/#/c/393283/|393283 (MobileFrontend): ApiMobileView: Disable 'deduplicateStyles' ParserOutput::getText() transformation]]
** [[https://gerrit.wikimedia.org/r/#/c/393284/|393284 (core): ParserOutput: Add 'deduplicateStyles' post-cache transformation]] (has an unaddressed -1)
** [[https://gerrit.wikimedia.org/r/#/c/393285/|393285 (TemplateStyles): Deduplicate embedded style rules]]
* post-cache transforms followup (not strictly related, but tech debt reduction for something that was introduced in part due to TemplateStyles):
** [[https://gerrit.wikimedia.org/r/#/c/393262/|393262 (core): Warn if stateful ParserOutput transforms are used]]
** [[https://gerrit.wikimedia.org/r/#/c/393263/|393263 (core): Hard-deprecate ParserOutput stateful transform methods]] (probably in a separate MW release)
* accurate edit previews
** [[https://gerrit.wikimedia.org/r/#/c/340768/|340768 (core): Generalize ResourceLoader 'excludepage' functionality]] (should be reviewed by an RL maintainer)
** [[https://gerrit.wikimedia.org/r/#/c/340769/|340769 (TemplateSandbox): Use new OutputPage::addContentOverride to allow previewing edits to JS/CSS]]
* [[https://gerrit.wikimedia.org/r/#/c/352835/|352835 (core): Add mw-parser-output to indicators container]] (needs to be rewritten)
* [[https://gerrit.wikimedia.org/r/#/c/347442/|347442 (core): ResourceLoader: Add wildcard modules]] (should be reviewed by an RL maintainer)