Artist identity remains owned by the artist profile. Attachment IDs are local to one WordPress site, not network-wide.

• extrachill/update-artist.profile_image_id uses the artist site’s media library.
• extrachill/save-link-page-settings.profile_image_id and the corresponding field on extrachill/artist-update-links use the Link Page storage site’s media library. 0 clears the image on both sites.
• The Link Page editor uploads its image into the Link Page storage site.

Identity pushes copy the source image into the destination library and store _ec_source_attachment = <source-blog-id>:<source-attachment-id> on the copy. Reverse saves use the same mapping and resolve an originating attachment rather than copying it back again. Repeated pushes reuse the materialized attachment. Copies have their own files and generated WordPress image metadata. Old copies are retained because they may be referenced elsewhere.

Migrated images are adopted without changing the page’s attachment ID only when the source and destination files have identical SHA-256 hashes. An ID collision or matching title is never sufficient. Missing/unreadable source files return an error rather than writing a foreign ID. This implementation requires local, readable source media files; offloaded media must expose a readable local file.

The owned-content backfill compares mapped image identity. Its dry run neither copies attachments nor adds tracking metadata. Run its apply mode on the artist site to repair stale pages:

wp --url=<artist-site> eval 'print_r( ec_artist_backfill_link_page_owned_content( true ) );'