On operation version compare page there'a s semaphore control, which shows number of changes between specific operation versions.
In a new approach introduced in GraphQL branches, we do not calculate changes between specific operation version on the client side, we reuse pre-processed document for the whole version to show diffs between operations. Hence we need a way to get changes summary for the specific operation versions from backend.

There's existing API (Get list of changed operations) that allow to get summary for operations in bulk, however, we need to be able to get changes for the specific operation versions. Another existing API which might be relevant for reference is Single operation change log, however, it returns actual changes, not summary of changes.

Proposed API:
Single operation changes summary

Request parameters are mostly the same as for Single operation change log

/api/v1/packages/{packageId}/versions/{version}/{apiType}/operations/{operationId}/changesSummary

Path Parameters

• apiType*, operationId*, packageId*, version*

Query Parameters

• previousVersion, previousVersionOperationId, previousVersionPackageId

Response could be based on Get list of changed operations but for the single operation.