refactor: ♻️ Add URI Collections and change all appropriate Collections to use them

app/changelog/page.mdx

@@ -22,6 +22,8 @@ This page lists changes since Working Draft 3. {{ className: 'lead' }}
     - In most cases, the two are interchangeable, but RFC 3339 is more strict. Most implementations should not need to change anything.
 - Add optional `$schema` field to [Entities](/entities).
 - Added [Interaction Controls Extensions](/extensions/interaction-controls)
+- Added [URI Collections](/structures/collection#uri-collection)
+    - Changed all Collections that can contain remote entities to use URI Collections (eg. [User](/entities/user) `collections.followers`).
 
 ## Since WD 3
 

app/entities/group/page.mdx

@@ -25,10 +25,10 @@ Refer to [Note](/entities/note#entity-definition)'s `group` property for how not
                 Text only (`text/plain`, `text/html`, etc).
             </Property>
             <Property name="members" type="URI" required={true} typeLink="/types#uri">
-                URI of the group's members list. [Collection](/structures/collection) of [Users](/entities/user).
+                URI of the group's members list. [URI Collection](/structures/collection#uri-collection) of [Users](/entities/user).
             </Property>
             <Property name="notes" type="URI" required={false} typeLink="/types#uri">
-                URI of the group's associated notes. [Collection](/structures/collection) of [Notes](/entities/note).
+                URI of the group's associated notes. [URI Collection](/structures/collection#uri-collection) of [Notes](/entities/note).
             </Property>
         </Properties>
     </Col>

app/entities/user/page.mdx

@@ -114,19 +114,19 @@ Instance **must** be the host of the instance the user is on (hostname with opti
             }
             ```
 
-            All URIs must resolve to a [Collection](/structures/collection) of the appropriate entities. Extensions may add additional collections.
+            All URIs must resolve to either a [Collection](/structures/collection) or a [URI Collection](/structures/collection#uri-collection) of the appropriate entities. Extensions may add additional collections.
 
             ### Outbox
-            The user's federation outbox. Refer to the [federation documentation](/federation).
+            The user's federation outbox. Refer to the [federation documentation](/federation). [Collection](/structures/collection) of [Note](/entities/note) entities.
 
             ### Followers
-            User's followers. [Collection](/structures/collection) of [User](/entities/user) entities.
+            User's followers. [URI Collection](/structures/collection#uri-collection) of [User](/entities/user) entities.
 
             ### Following
-            Users that the user follows. [Collection](/structures/collection) of [User](/entities/user) entities.
+            Users that the user follows. [URI Collection](/structures/collection#uri-collection) of [User](/entities/user) entities.
 
             ### Featured
-            [Notes](/entities/note) that the user wants to feature (also known as "pin") on their profile. [Collection](/structures/collection) of [Note](/entities/note) entities.
+            [Notes](/entities/note) that the user wants to feature (also known as "pin") on their profile. [Collection](/structures/collection) of [Note](/entities/note) entities. Only notes authored by the user can be featured.
         </Property>
     </Properties>
 

app/extensions/interaction-controls/page.mdx

@@ -102,7 +102,7 @@ Extensions **may** choose to register their own interaction types (such as `pub.
 
 Implementations that find a user attempting to create an interaction they are not allowed to **MUST** return a `403 Forbidden` HTTP status code when processing the Note during federation. The Note **must** also be discarded.
 
-It is important for implementations to backfill any related [Collections](/structures/collection) (e.g. user followers) in order to not incorrectly reject Notes based off of outdated data.
+It is important for implementations to backfill any related [Collections](/structures/collection)/[URI Collections](/structures/collection#uri-collection) (e.g. user followers) in order to not incorrectly reject Notes based off of outdated data.
 
 <Note>
     To avoid server load from constant Collection refreshing, implementations **could** only refetch associated Collections when forbidden interactions are detected, then recalculate permissions again.

app/extensions/likes/page.mdx

@@ -92,8 +92,8 @@ To undo a like or dislike, a [Delete](/entities/delete) entity should be used. T
 
 The Likes extension adds the following collections to the [User](/entities/user) entity:
 
-- `likes`: A [Collection](/structures/collection) of all the notes the user has liked.
+- `likes`: A [URI Collection](/structures/collection#uri-collection) of all the notes the user has liked.
-- `dislikes`: A [Collection](/structures/collection) of all the notes the user has disliked.
+- `dislikes`: A [URI Collection](/structures/collection#uri-collection) of all the notes the user has disliked.
 
 ```jsonc
 {

app/extensions/reactions/page.mdx

@@ -58,7 +58,7 @@ The Reactions Extension extends the [Note](/entities/note) entity with the follo
     <Col>
         <Properties>
             <Property name="reactions" type="array" required>
-                URI to a [Collection](/structures/collection) of the [Reactions](#entity-definition) attached to the note.
+                URI to a [URI Collection](/structures/collection#uri-collection) of the [Reactions](#entity-definition) attached to the note.
             </Property>
         </Properties>
     </Col>

app/federation/page.mdx

@@ -39,6 +39,6 @@ Shared inboxes are defined in the [Instance Metadata](/entities/instance-metadat
 
 ## Outboxes
 
-In addition to inboxes, every user has an outbox (e.g., `/users/3/outbox`). The outbox is simply a collection of all the messages that a user has sent. When a user sends a message to another user, a copy of that message is accessible in the sender's outbox.
+In addition to inboxes, every user has an outbox (e.g., `/users/3/outbox`). The outbox is simply a [Collection](/structures/collection) of all the messages that a user has sent. When a user sends a message to another user, a copy of that message is accessible in the sender's outbox.
 
 Outboxes are very useful for "backfilling" data when a new instance joins the network. By resolving the outboxes of all new users it encounters, a new instance can quickly catch up on all old messages.

app/structures/collection/page.mdx

@@ -77,3 +77,60 @@ Pages should be limited to a reasonable number of entities, such as 20 or 80.
 
     </Col>
 </Row>
+
+## URI Collection
+
+URI Collections are identical to regular collections, but they contain only URIs instead of full entities. They are useful for cases when remote entities need to be included in a collection, as those are typically not stored in implementation databases. {{ className: 'lead' }}
+
+<Row>
+    <Col>
+        <Properties>
+            <Property name="author" type="URI | null" required={true} typeLink="/types#uri">
+                Author of the collection. Usually the user who owns the collection. [Can be set to `null` to represent the instance](/entities/instance-metadata#the-null-author).
+            </Property>
+            <Property name="first" type="URI" required={true} typeLink="/types#uri">
+                URI to the first page of the collection. Query parameters are allowed.
+            </Property>
+            <Property name="last" type="URI" required={true} typeLink="/types#uri">
+                URI to the last page of the collection. Query parameters are allowed.
+                
+                If the collection only has one page, this should be the same as `first`.
+            </Property>
+            <Property name="total" type="number" required={true} numberType="u64">
+                Total number of entities in the collection, across all pages.
+            </Property>
+            <Property name="next" type="URI" required={false} typeLink="/types#uri">
+                URI to the next page of the collection. Query parameters are allowed.
+                
+                If there is no next page, this should be `null`.
+            </Property>
+            <Property name="previous" type="URI" required={false} typeLink="/types#uri">
+                URI to the previous page of the collection. Query parameters are allowed.
+                
+                If there is no previous page, this should be `null`.
+            </Property>
+            <Property name="items" type="URI[]" required={true}>
+                Collection contents. Must be an array of URIs.
+            </Property>
+        </Properties>
+    </Col>
+
+    <Col sticky>
+
+    ```jsonc {{ 'title': 'Example URI Collection' }}
+    {
+        "author": "https://versia.social/users/018ec082-0ae1-761c-b2c5-22275a611771",
+        "first": "https://versia.social/users/018ec082-0ae1-761c-b2c5-22275a611771/followers?page=1",
+        "last": "https://versia.social/users/018ec082-0ae1-761c-b2c5-22275a611771/followers?page=3",
+        "total": 46,
+        "next": "https://versia.social/users/018ec082-0ae1-761c-b2c5-22275a611771/followers?page=2",
+        "previous": null,
+        "items": [
+            "https://versia.social/users/f8b0d4b4-d354-4798-bbc5-c2ba8acabfe3",
+            "https://social.bob.com/u/2B27E62snga763"
+        ]
+    }
+    ```
+
+    </Col>
+</Row>