Where-ever an app API request makes an assumption about content (e.g. this class will be present and mean x, this attribute will be preset).
Examples:
- We use srcset on img tags so this must be present
- We assume images are captured in img tags. e.g. not figure
- The infobox can be identified by having the class infobox
Outcome:
Please fold assumptions into a task so reading web team can capture these things in test (see T139003)