When Wikidiff2 is installed, users have the ability to use the inline diff format. We should expose this in the Compare API.
When loading a diff, the HTML is already present on page load. In this example, we have the inline option set via the URL parameter. In this case, the dropdown we'll be introducing (T330229) will have inline already selected. If the user were to then select two-column, we'd make a request to the Compare API with difftype=two-column, and vice versa if the on page load the diff type was two-column.
The new difftype parameter could instead be a boolean parameter, such as diffinline, but perhaps it's better to leave it open for other diff types, say if VisualEditor-VisualDiffs were to ever make it to Core.
Acceptance criteria
- If wikidiff2 is installed, the action=compare endpoint should offer a difftype parameter (we'll use difftype instead of diff-type because seemingly all multi-word action API parameters don't have hyphens).
- The difftype parameter should accept two values: inline or table (wikidiff2 calls the latter source but I think that's a bit confusing).
- If no difftype is provided, table should be the default (later this will go by user preference)
- If an invalid difftype is provided, the API should return a badvalue error
