Wikimedia Bugzilla is closed!

Expose template parameters in a JSON array as described in https://www.mediawiki.org/wiki/Parsoid/MediaWiki_DOM_spec#Non-semantic_parameter_editing, so that the Visual Editor folks can start playing with it.

In a second step, add basic editing support without escaping.

Finally, add escaping for template parameters.

Editing support for page content caught up in a multi-template DOM structure is something we should probably defer for now. It would either require *very* powerful escaping logic (I'd venture the guess that it is actually possible with template interaction), or a wrapper extension tag that enforces DOM nesting for the entire block in both the PHP parser and Parsoid. Until we have that, we should still expose the content as strings as in the spec to provide read-only wikitext context for editors, but ignore changes to those strings when serializing modified template content.