As an AMP story creator, I would like to ensure my AMP stories are validated, and error free, and the interface provides me with feedback or validation information, to update my stories to include all required elements for AMP.

• AC 1: Surface AMP Errors and Validation inside the Stories Editor
• AC 2: Add conditional validation to meet the AMP Stories spec. e.g.
  • AC 3: Featured image (validation to require this)
  • AC 4: Missing properties inside tags
  • AC 4: Poster image in Video
  • AC 4: Disallowing Illegal HTML elements
• AC 5: Show AMP errors inside the editor to match other post editing. (Note: Currently, the sanitizer errors are not reported in the interface.)
• AC 6: Published AMP stories should suppress validation errors, e.g. refine the AMP plugin sanitizers to add missing elements, strip the content that fails validation and alert the user.
  • AC 7: An author should be able to save and publish AMP stories that have caught errors (as is handled by Gutenberg currently), but content should be sanitized to prevent validation errors from leaking to the front end.