Setup

Grant these before you write any code. Every method fails with an access error without them.

A caller - Apex running user, or the running user of a flow - requires both:

1. Files API Access custom permission (sliick__SliickFilesAPI). Ships enabled in the SliickFilesAdmin permission set. For other users, add the custom permission to a permission set.
2. Data access - the SliickFilesUser permission set, or equivalent CRUD/FLS on sliick__Cloud_File__c and sliick__Cloud_File_Link__c. All queries and DML run in USER_MODE; record-level sharing applies per item.

The custom permission is the entitlement gate. The sharing model governs which records and files each call can act on.