WordPress ships with a native Lightbox-Effect for image and gallery blocks. This plugin adds one focused editor option to standalone core Image blocks: Join gallery.
When the native Lightbox-Effect is enabled on an Image block, the block inspector shows all Lightbox-enabled Gallery blocks on the current page. Select one of them and the standalone image becomes part of that gallery’s native lightbox navigation group on the frontend.
The plugin does not replace the core Image or Gallery blocks. It stores a stable internal lightbox group ID on Gallery blocks and a selected group ID on standalone Image blocks. During rendering, it uses the same WordPress Interactivity API context that the core Gallery block uses for native lightbox navigation.
For a more readable editor experience, gallery captions are used as select labels when available. If a gallery has no caption, the plugin falls back to a numbered label with the image count.
Plugin Features
✔ extends the existing core Image and Gallery blocks
✔ adds a Join gallery selector to standalone Image blocks
✔ only shows the selector when the native Lightbox-Effect is active
✔ only lists Gallery blocks whose native Lightbox-Effect is active
✔ uses Gallery captions as human-readable select labels
✔ stores stable internal group IDs on Gallery blocks
✔ wraps selected standalone Image blocks in the required core/gallery interactivity context
✔ keeps the native WordPress lightbox overlay and navigation behavior
✔ ships with English and German PO, MO and JSON translation files
✔ uses no build step and no custom replacement block