Parsoid HTML (and data-parsoid) is stored in RESTBase with a version number. This lets us make breaking changes to the HTML once in a while (as required). Clients / Parsoid would then have to do the right thing based on version (simplest would be to reject any requests that include an older version HTML and force-fetch updated HTML).
We need to nail down the process of what is involved in supporting this.
On the Parsoid end, we need to add a wiki page where HTML version number changes are documented as part of a ChangeLog.
On the RESTBase end, maybe it needs to provide an API end point where clients can request HTML with the latest version (or a specific version)?
How will clients like VE, Flow, CX handle this?