Thank you! To clarify it's been API contracts in the DNS record setting API that have hit me. I'm going from memory here and it's been a couple years I think so might be a bit rusty, but one example was a slight change in data type acceptance for TTL on a record. It used to take either a string or integer in the JSON but at some point started rejecting integers (or strings, whichever one I was sending at the time stopped being accepted) so the API calls were suddenly failing (to be fair that might not have technically been a violation of the contract, but it was a change in behavior that had been consistent for years and which I would not have expected). Another one was regarding returning zone_id for records where the zone_id stopped getting populated in the returned record. Luckily my code already had the zone_id because it needs that to build the URL path, but it was a rough debugging session and then I had to hack around it by either re-adding the zone ID to the returned record or removing zone ID from my equality check, neither of which were preferred solutions.

If we start using workers though I'll definitely let you know if any API changes!