What changed since you integrated

An agent that generated a client last week has no way to learn what changed. Human changelogs are prose on a marketing page — unparseable, usually stale, and silent about the only thing a running integration cares about: whether something it depends on has BROKEN. So integrators either pin forever and miss every improvement, or re-fetch the whole spec on a schedule and diff it themselves. Both are the provider's failure pushed onto the consumer. Pass since and you get only what changed after that version. CHECK mustAct FIRST — if true, there are breaking changes and your integration may already be failing; each such entry carries an action. breaking:true means an existing CORRECT integration could stop working. It is a compatibility claim, not a measure of importance, and nothing that qualifies is downgraded because it looks bad. Every path claimed here is cross-checked against the live spec on each request; drift is reported rather than hidden, because a changelog is believed.