A way to know permission changes via API

Hi,

I have to store Confluence content in a database so it can be found in an external search web application. I can get the last modified date of e.g. a page via Confluence REST API and cql (e.g. /rest/api/content/search?cql=space=ds and lastModified > lastStoredTimeStamp and type = page).

We want the process of storing confluence content be incremental (e.g. update only modified pages in the database). The problem is that a permission change doesn't update the last modified timestamp (e.g. history.lastUpdated field of the REST API answer). Is there a way to know permission changes via any Confluence API?

I need to answer the following questions:
Is there a way to know when a Confluence document is updated? Yes, via REST API
Is there a way to know when a Confluence document permission is updated?
Is there a way to know when a Confluence user account changes e.g. joins/leaves a group?

Permission Changes (History) should be available via API.