An analysis of the idea to implement an image object block in the WordPress Block Editor.

[Jiwoon-Kim]

An analysis of the idea to implement an image object block in the WordPress Block Editor.

Based on the current progress, I believe it is appropriate to open an issue for this. The following content likely pertains to information that should be included in the json-ld of a media attachment post.

1. Included in the body (content). 2. Included in the attachment. 3. Included in comments.

---

1. Included in the body (content)

Inclusion of an ActivityPub object within the body itself is a non-standard interaction. However, it appears to be a feasible feature to implement within WordPress.

Currently, an image included in the body is not an ActivityPub object; it's an HTML array (typically within a gallery block). However, it could be made interactive via the Jetpack carousel.

In federation, the wp-block-gallery is replaced with ap-block-gallery.
This would allow all images to become interactive image objects if the follower is a WordPress instance.

Feature Idea

• Support Attachment Post Links in the Gallery Block
  → Provide a compatibility option to the image object block in the block editor. When inserting images into a gallery, it would allow the retrieval of an image from a ?attachment_id=123 permalink instead of a simple file URL.
  → There's no need to load the entire object; you only need to retrieve the file path URL, the URL of the post type: attachment, and the author ID. This could be considered a non-standard interaction and might be a Jetpack-specific mechanism.

• Image-Level Federation
  → This allows for direct interaction with a media library's Image object, rather than a simple hotlink to an image within the post body.

• Image Carousel and Comments
  → On my instance, images can be viewed individually in the image carousel (=Gallery UI).
  → A user on a remote instance can directly send actions like comments or likes to a specific Image Object.
  → In short, it enables interaction at the image level, not just with the entire post.

Technical Considerations

• The ActivityPub plugin must add logic to convert ?attachment_id=123 into an Image Object.
• Interactions like comments or likes must be mapped to direct actions with the Image object in the ActivityStreams 2.0 specification.

---

2. Included in the attachment

This model involves directly including a remote instance's Image object in the attachment array of your post (Note or Article), rather than simply embedding an <img> tag. This would create a concept like a WordPress "Shared Media Library."

According to GPT, the core question is whether the attachment must be an "image from the original instance." In the specification, that's not a requirement.

• The attachment field can simply include an object like { "type": "Image", "id": "https://remote.instance/media/123", "url": "…" }.
• The id must be the original image object's id from the source instance.
• This turns your post into a simple statement of "This Note attaches that object," and the remote instance can handle interactions with its own Image object.

In short, just as Facebook bundles notes, images, and video objects within a single post, ActivityPub can also pull content using a "reference model."

---

3. Included in comments

This involves displaying images included in comments received via the inbox. If you can display image objects in the body, it would naturally be possible to display them in comments as well.

---

An example of an ActivityStreams 2.0 Image Object that includes the WordPress Media Library structure, various resized/rotated versions, and an extension field (as:license):

{
  "@context": [
    "https://www.w3.org/ns/activitystreams",
    {
      "as:license": "https://www.w3.org/ns/activitystreams#license"
    }
  ],
  "id": "https://travel-in-busan.com/?attachment_id=18735",
  "type": "Image",
  "name": "A cup of black coffee and a croissant pastry on a wooden tray",
  "attributedTo": "https://kimjiwoon96.wordpress.com/?author=1",
  "mediaType": "image/webp",
  "url": [
    {
      "type": "Link",
      "href": "https://travel-in-busan.com/wp-content/uploads/2025/08/20250522_160858-150x150.jpg",
      "mediaType": "image/webp",
      "width": 150,
      "height": 150,
      "name": "Thumbnail"
    },
    {
      "type": "Link",
      "href": "https://travel-in-busan.com/wp-content/uploads/2025/08/20250522_160858-300x300.jpg",
      "mediaType": "image/webp",
      "width": 300,
      "height": 300,
      "name": "Medium"
    },
    {
      "type": "Link",
      "href": "https://travel-in-busan.com/wp-content/uploads/2025/08/20250522_160858-1024x1024.jpg",
      "mediaType": "image/webp",
      "width": 1024,
      "height": 1024,
      "name": "Large"
    },
    {
      "type": "Link",
      "href": "https://travel-in-busan.com/wp-content/uploads/2025/08/20250522_160858-2560x2560.jpg",
      "mediaType": "image/webp",
      "width": 2560,
      "height": 2560,
      "name": "Full-size"
    }
  ],
  "as:license": "https://creativecommons.org/licenses/by/4.0/"
}

---

The extension field license can be a custom extension like as:license.

[Jiwoon-Kim]

The concept of an "inter-instance shared media library" is introduced.

By adopting a "reference-first + selective caching" model at the ActivityPub level, both the issues of unauthorized reproduction and junk data on the network can be solved simultaneously.

This is not about technical convenience; it's about solving the problems of copyright/commercial unauthorized reproduction and global data duplication (junk data) at the same time.

• "Only one original entity"
• Other instances use only a reference.
• This is a method that prevents the creation of new duplicates every time a user pastes or shares content.

👉 This allows for simultaneous copyright management and network data optimization.

---

🔹 The Proposed Model

1. Canonical Media Object

   • Assign a single Image/Video object ID on the original instance.
   • Other instances do not duplicate it but use it only as an attachment reference.

2. Federated Media Library (a distributed Pinterest/Tenor/Giphy)

   • All instances can share the same media objects.
   • However, all interactions (comments, likes, etc.) are attributed to the original object.

3. CDN-like Caching

   • Relying solely on remote references would be slow due to performance issues.
   • Therefore, a local instance can hold a cached file, but at the ActivityPub level, it always retains the original ID → This enables ownership/copyright tracking.

---

🔹 Expected Effects

• ✅ Reduces Unauthorized Reproduction: Only the original object uploaded by the copyright holder exists.
• ✅ Global Network Optimization: Prevents the same image from being stored 100 times on different instances.
• ✅ Interaction Consistency: Likes, comments, and shares are attributed to the original object → engagement data is not fragmented.
• ✅ Service Scalability: Can be expanded to features like a global "Fediverse media search" in the future (like the Giphy API).

---

🔹 Problems / Challenges

1. Permissions & Accessibility

   • If the source instance does not publicly federate the Image object, it will break when your post tries to load it.
   • Without a caching layer (like a CDN), you will constantly be dependent on the original server's traffic.

2. WordPress Plugin Level

   • The current WP ActivityPub plugin only serializes "my own attachments (Post Attachments)."
   • It does not have a feature to pull external objects into the attachment array. (This would require customization).

3. UX Issues

   • Users might get confused: "Is this image in my media library?" "What happens if the original gets deleted?"
   • Clients like Mastodon need to distinguish between a "shared object" and an "object I uploaded."

---

🔹 Approaches for Implementation

1. Embed as Reference:

   • Extend the plugin to allow external Image object IDs in the attachment array.
   • This would allow remote instances to send activities like comments and likes directly to the original object.

2. Shared Media Cache (Extended Concept):

   • Temporarily save the external image as a "local attachment," using a local CDN for the url but keeping the original id.
   • This provides a better user experience, making it look like it's in the local library while still federating interactions to the original object.

---

📌 Conclusion:

• This is not possible with the current default WordPress ActivityPub plugin structure.
• However, it is completely valid according to the ActivityStreams specification.
• To implement it, you would need to introduce a strategy of allowing external object references + caching → this can function as an "inter-instance shared media library."

[obenland]

Not in scope

[Jiwoon-Kim]

I hope this will be discussed again within a few months after the plugin’s next update.

[Jiwoon-Kim]

https://codeberg.org/fediverse/fep/src/branch/main/fep/c118/fep-c118.md