Metadata cascade explained

Each photo has its own IPTC fields (city, country, credit, copyright, etc.). When a per-photo field is empty, the album's default value is used at read-time. This is the cascade:

photo.city is NULL → fall back to album.event_city
photo.copyright is NULL → fall back to album.copyright_override

The inspector shows cascade in action: fields that came from the album default get a thin sky-blue border and a tooltip saying "Inherited from album default". Typing into the field overrides the cascade — the value gets written explicitly on the photo.

To clear an override and re-engage the cascade: empty the field and save. The server treats empty-string saves as "delete this override".