Feed: new ?full=1 parameter adds a content object to each item with the full body (summary_html, steps, sample_texts, links, videos, button_text), so apps and partner sites can show a complete action without an authenticated request.
Feed: every item now carries a modified timestamp in UTC, so a service watching the feed can tell a new action from an edited one.
Feed: image is now the 768px size instead of 300px, which looks far better on a phone. The old size is still available as image_small.
All changes are additive. Existing consumers keep working untouched.