response-required-property-removed

What this check detects

A property that the response was guaranteed to include, it was listed under `required`, has been removed. Clients that read that field and rely on it always being present break when it disappears.

Removing a required response property is breaking. Removing an optional one is reported as a warning instead, because a well-written client should already tolerate its absence, though not all do.

Example

The guaranteed "email" field is gone. A client that reads response.email now finds it missing.

How to handle this change

When oasdiff flags response-required-property-removed, you have a few ways to respond:

• Find a backward-compatible alternative. Redesign the change so clients that followed the old contract keep working, and agree on the approach with whoever introduced it.
• Release it in a new API version. Keep the current contract and introduce the change in a new version, then deprecate the old one with a sunset date so clients have time to migrate.
• Accept it as a deliberate breaking change. Sometimes a breaking change is unavoidable, such as an urgent or security fix. Approve it knowingly, document it in your release notes, and tell affected clients. This should be the exception, not a routine way of working.

If oasdiff's verdict does not match your API's compatibility policy, you can also change how it treats response-required-property-removed with a severity-levels file:

Put one rule per line; the level can be err, warn, or info, or none to disable the check entirely:

# severity.txt
response-required-property-removed warn

Then pass it to oasdiff:

oasdiff changelog base.yaml revision.yaml --severity-levels severity.txt