From 97826b463dfa8d8e3f7d8586ba2ea71527b73e3c Mon Sep 17 00:00:00 2001
From: Jesse Karmani <jessekarmani@gmail.com>
Date: Thu, 2 Jan 2025 18:36:23 -0800
Subject: [PATCH 1/7] Set context for a note to the parent note of the
 conversation

---
 app/serializers/activitypub/note_serializer.rb | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/app/serializers/activitypub/note_serializer.rb b/app/serializers/activitypub/note_serializer.rb
index 2b0e3d37d7e429..68eb8180b0a444 100644
--- a/app/serializers/activitypub/note_serializer.rb
+++ b/app/serializers/activitypub/note_serializer.rb
@@ -158,8 +158,9 @@ def conversation
 
   def context
     return if object.conversation.nil?
+    return if object.conversation.parent_status.nil?
 
-    ActivityPub::TagManager.instance.uri_for(object.conversation)
+    ActivityPub::TagManager.instance.uri_for(object.conversation.parent_status)
   end
 
   def local?

From 536922bccfe3730ba331bb2d3e52da04972193dd Mon Sep 17 00:00:00 2001
From: Jesse Karmani <jessekarmani@gmail.com>
Date: Wed, 8 Jan 2025 22:47:45 -0800
Subject: [PATCH 2/7] Change ActivityPub note context to be a resolvable
 collection

---
 .../activitypub/contexts_controller.rb        | 44 +++++++++++++++++++
 app/lib/activitypub/tag_manager.rb            |  8 ++++
 app/models/user.rb                            |  2 -
 .../activitypub/context_serializer.rb         |  8 +---
 .../activitypub/note_serializer.rb            | 15 ++++++-
 config/routes.rb                              |  4 +-
 .../activitypub/note_serializer_spec.rb       | 24 ++++++----
 7 files changed, 87 insertions(+), 18 deletions(-)

diff --git a/app/controllers/activitypub/contexts_controller.rb b/app/controllers/activitypub/contexts_controller.rb
index 0d30349899444f..786c0db82d48b3 100644
--- a/app/controllers/activitypub/contexts_controller.rb
+++ b/app/controllers/activitypub/contexts_controller.rb
@@ -2,15 +2,59 @@
 
 class ActivityPub::ContextsController < ActivityPub::BaseController
   before_action :set_conversation
+  before_action :set_items, only: :items
+
+  DESCENDANTS_LIMIT = 60
 
   def show
     expires_in 3.minutes, public: public_fetch_mode?
     render_with_cache json: @conversation, serializer: ActivityPub::ContextSerializer, adapter: ActivityPub::Adapter, content_type: 'application/activity+json'
   end
 
+  def items
+    expires_in 3.minutes, public: public_fetch_mode?
+    render_with_cache json: items_collection_presenter, serializer: ActivityPub::CollectionSerializer, adapter: ActivityPub::Adapter, content_type: 'application/activity+json'
+  end
+
   private
 
   def set_conversation
     @conversation = Conversation.local.find(params[:id])
   end
+
+  def set_items
+    @items = @conversation.statuses.distributable_visibility.paginate_by_min_id(DESCENDANTS_LIMIT, params[:min_id])
+  end
+
+  def items_collection_presenter
+    page = ActivityPub::CollectionPresenter.new(
+      id: context_items_url(@conversation, page_params),
+      type: :unordered,
+      part_of: context_items_url(@conversation),
+      next: next_page,
+      items: @conversation.statuses.map { |status| status.local? ? status : status.uri }
+    )
+
+    return page if page_requested?
+
+    ActivityPub::CollectionPresenter.new(
+      id: context_items_url(@conversation),
+      type: :unordered,
+      first: page
+    )
+  end
+
+  def page_requested?
+    truthy_param?(:page)
+  end
+
+  def next_page
+    return nil if @conversation.statuses.size < DESCENDANTS_LIMIT
+
+    context_items_url(@conversation, page: true, min_id: @conversation.statuses.last.id)
+  end
+
+  def page_params
+    params.permit(:page, :min_id)
+  end
 end
diff --git a/app/lib/activitypub/tag_manager.rb b/app/lib/activitypub/tag_manager.rb
index 0cec0f2750eae7..dc2a5e4884c067 100644
--- a/app/lib/activitypub/tag_manager.rb
+++ b/app/lib/activitypub/tag_manager.rb
@@ -39,6 +39,8 @@ def uri_for(target)
     case target.object_type
     when :person
       target.instance_actor? ? instance_actor_url : account_url(target)
+    when :conversation
+      context_url(target)
     when :note, :comment, :activity
       return activity_account_status_url(target.account, target) if target.reblog?
 
@@ -68,6 +70,12 @@ def activity_uri_for(target)
     activity_account_status_url(target.account, target)
   end
 
+  def context_uri_for(target, page_params = nil)
+    raise ArgumentError, 'target must be a local activity' unless %i(note comment activity).include?(target.object_type) && target.local?
+
+    context_items_url(target.conversation, page_params)
+  end
+
   def replies_uri_for(target, page_params = nil)
     raise ArgumentError, 'target must be a local activity' unless %i(note comment activity).include?(target.object_type) && target.local?
 
diff --git a/app/models/user.rb b/app/models/user.rb
index 675a20f47c7e36..fa1a275bbd0c61 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -128,8 +128,6 @@ class User < ApplicationRecord
   scope :matches_ip, ->(value) { left_joins(:ips).where('user_ips.ip <<= ?', value).group('users.id') }
 
   before_validation :sanitize_role
-  before_validation :sanitize_time_zone
-  before_validation :sanitize_locale
   before_create :set_approved
   after_commit :send_pending_devise_notifications
   after_create_commit :trigger_webhooks
diff --git a/app/serializers/activitypub/context_serializer.rb b/app/serializers/activitypub/context_serializer.rb
index 99ef9a73b9a8e2..fa4e057c1a99ab 100644
--- a/app/serializers/activitypub/context_serializer.rb
+++ b/app/serializers/activitypub/context_serializer.rb
@@ -3,17 +3,13 @@
 class ActivityPub::ContextSerializer < ActivityPub::Serializer
   include RoutingHelper
 
-  attributes :id, :type, :inbox
+  attributes :id, :type
 
   def id
     ActivityPub::TagManager.instance.uri_for(object)
   end
 
   def type
-    'Group'
-  end
-
-  def inbox
-    account_inbox_url(object.parent_account)
+    'Collection'
   end
 end
diff --git a/app/serializers/activitypub/note_serializer.rb b/app/serializers/activitypub/note_serializer.rb
index 68eb8180b0a444..62d2b50f721030 100644
--- a/app/serializers/activitypub/note_serializer.rb
+++ b/app/serializers/activitypub/note_serializer.rb
@@ -19,6 +19,7 @@ class ActivityPub::NoteSerializer < ActivityPub::Serializer
   has_many :virtual_tags, key: :tag
 
   has_one :replies, serializer: ActivityPub::CollectionSerializer, if: :local?
+  has_one :context, serializer: ActivityPub::CollectionSerializer, if: :local?
   has_one :likes, serializer: ActivityPub::CollectionSerializer, if: :local?
   has_one :shares, serializer: ActivityPub::CollectionSerializer, if: :local?
 
@@ -160,7 +161,19 @@ def context
     return if object.conversation.nil?
     return if object.conversation.parent_status.nil?
 
-    ActivityPub::TagManager.instance.uri_for(object.conversation.parent_status)
+    conversation_statuses = object.conversation.statuses[0..5].pluck(:id, :uri)
+    last_id = conversation_statuses.last&.first
+
+    ActivityPub::CollectionPresenter.new(
+      type: :unordered,
+      id: ActivityPub::TagManager.instance.uri_for(object.conversation),
+      first: ActivityPub::CollectionPresenter.new(
+        type: :unordered,
+        part_of: ActivityPub::TagManager.instance.uri_for(object.conversation),
+        items: conversation_statuses.map(&:second),
+        next: last_id ? ActivityPub::TagManager.instance.context_uri_for(object, page: true, min_id: last_id) : ActivityPub::TagManager.instance.context_uri_for(object, page: true, only_other_accounts: true)
+      )
+    )
   end
 
   def local?
diff --git a/config/routes.rb b/config/routes.rb
index 3262fecb5d307b..f20086bfa48256 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -143,7 +143,9 @@ def redirect_with_vary(path)
   end
 
   resource :inbox, only: [:create], module: :activitypub
-  resources :contexts, only: [:show], module: :activitypub
+  resources :contexts, only: [:show], module: :activitypub do
+    resources :items, only: [:index], module: :activitypub
+  end
 
   constraints(encoded_path: /%40.*/) do
     get '/:encoded_path', to: redirect { |params|
diff --git a/spec/serializers/activitypub/note_serializer_spec.rb b/spec/serializers/activitypub/note_serializer_spec.rb
index a6976193b20ec1..8aa9be02b76688 100644
--- a/spec/serializers/activitypub/note_serializer_spec.rb
+++ b/spec/serializers/activitypub/note_serializer_spec.rb
@@ -7,11 +7,11 @@
 
   let!(:account) { Fabricate(:account) }
   let!(:other) { Fabricate(:account) }
-  let!(:parent) { Fabricate(:status, account: account, visibility: :public, language: 'zh-TW') }
-  let!(:reply_by_account_first) { Fabricate(:status, account: account, thread: parent, visibility: :public) }
-  let!(:reply_by_account_next) { Fabricate(:status, account: account, thread: parent, visibility: :public) }
-  let!(:reply_by_other_first) { Fabricate(:status, account: other, thread: parent, visibility: :public) }
-  let!(:reply_by_account_third) { Fabricate(:status, account: account, thread: parent, visibility: :public) }
+  let!(:parent) { Fabricate(:status, account: account, visibility: :private, language: 'zh-TW') }
+  let!(:reply_by_account_first) { Fabricate(:status, account: account, thread: parent, visibility: :private) }
+  let!(:reply_by_account_next) { Fabricate(:status, account: account, thread: parent, visibility: :private) }
+  let!(:reply_by_other_first) { Fabricate(:status, account: other, thread: parent, visibility: :private) }
+  let!(:reply_by_account_third) { Fabricate(:status, account: account, thread: parent, visibility: :private) }
   let!(:reply_by_account_visibility_direct) { Fabricate(:status, account: account, thread: parent, visibility: :direct) }
 
   it 'has the expected shape and replies collection' do
@@ -22,16 +22,24 @@
       'contentMap' => include({
         'zh-TW' => a_kind_of(String),
       }),
+      'context' => include(
+        'type' => 'Collection',
+        'first' => include(
+          'type' => 'CollectionPage',
+          'items' => include(parent.uri, reply_by_account_first.uri, reply_by_account_next.uri,
+                             reply_by_account_third.uri, reply_by_other_first.uri)
+        )
+      ),
       'replies' => replies_collection_values,
     })
   end
 
   def replies_collection_values
     include(
-      'type' => eql('Collection'),
+      'type' => 'Collection',
       'first' => include(
-        'type' => eql('CollectionPage'),
-        'items' => reply_items
+        'type' => 'CollectionPage',
+        'items' => []
       )
     )
   end

From 19795386754c00f517d3527777183ec057094a04 Mon Sep 17 00:00:00 2001
From: Jesse Karmani <jessekarmani@gmail.com>
Date: Mon, 13 Jan 2025 13:44:31 -0800
Subject: [PATCH 3/7] Set context for a note to the url of the conversation and
 return the collection when that is resolved

---
 .../activitypub/context_serializer.rb          | 18 +++++++++++++++++-
 app/serializers/activitypub/note_serializer.rb | 16 ++--------------
 .../activitypub/note_serializer_spec.rb        |  9 +--------
 3 files changed, 20 insertions(+), 23 deletions(-)

diff --git a/app/serializers/activitypub/context_serializer.rb b/app/serializers/activitypub/context_serializer.rb
index fa4e057c1a99ab..19ebe5b088d87b 100644
--- a/app/serializers/activitypub/context_serializer.rb
+++ b/app/serializers/activitypub/context_serializer.rb
@@ -3,7 +3,9 @@
 class ActivityPub::ContextSerializer < ActivityPub::Serializer
   include RoutingHelper
 
-  attributes :id, :type
+  attributes :id, :type, :first
+
+  has_one :first, serializer: ActivityPub::CollectionSerializer
 
   def id
     ActivityPub::TagManager.instance.uri_for(object)
@@ -12,4 +14,18 @@ def id
   def type
     'Collection'
   end
+
+  def first
+    conversation_statuses = object.statuses[0..5]
+    last_status = conversation_statuses.last
+    conversation_statuses = conversation_statuses.pluck(:id, :uri)
+    last_id = conversation_statuses.last&.first
+
+    ActivityPub::CollectionPresenter.new(
+      type: :unordered,
+      part_of: ActivityPub::TagManager.instance.uri_for(object),
+      items: conversation_statuses.map(&:second),
+      next: last_id ? ActivityPub::TagManager.instance.context_uri_for(last_status, page: true, min_id: last_id) : ActivityPub::TagManager.instance.context_uri_for(last_status, page: true, only_other_accounts: true)
+    )
+  end
 end
diff --git a/app/serializers/activitypub/note_serializer.rb b/app/serializers/activitypub/note_serializer.rb
index 62d2b50f721030..313d4943a84583 100644
--- a/app/serializers/activitypub/note_serializer.rb
+++ b/app/serializers/activitypub/note_serializer.rb
@@ -18,8 +18,8 @@ class ActivityPub::NoteSerializer < ActivityPub::Serializer
   has_many :virtual_attachments, key: :attachment
   has_many :virtual_tags, key: :tag
 
+  has_one :context
   has_one :replies, serializer: ActivityPub::CollectionSerializer, if: :local?
-  has_one :context, serializer: ActivityPub::CollectionSerializer, if: :local?
   has_one :likes, serializer: ActivityPub::CollectionSerializer, if: :local?
   has_one :shares, serializer: ActivityPub::CollectionSerializer, if: :local?
 
@@ -161,19 +161,7 @@ def context
     return if object.conversation.nil?
     return if object.conversation.parent_status.nil?
 
-    conversation_statuses = object.conversation.statuses[0..5].pluck(:id, :uri)
-    last_id = conversation_statuses.last&.first
-
-    ActivityPub::CollectionPresenter.new(
-      type: :unordered,
-      id: ActivityPub::TagManager.instance.uri_for(object.conversation),
-      first: ActivityPub::CollectionPresenter.new(
-        type: :unordered,
-        part_of: ActivityPub::TagManager.instance.uri_for(object.conversation),
-        items: conversation_statuses.map(&:second),
-        next: last_id ? ActivityPub::TagManager.instance.context_uri_for(object, page: true, min_id: last_id) : ActivityPub::TagManager.instance.context_uri_for(object, page: true, only_other_accounts: true)
-      )
-    )
+    ActivityPub::TagManager.instance.uri_for(object.conversation)
   end
 
   def local?
diff --git a/spec/serializers/activitypub/note_serializer_spec.rb b/spec/serializers/activitypub/note_serializer_spec.rb
index 8aa9be02b76688..6d739042268038 100644
--- a/spec/serializers/activitypub/note_serializer_spec.rb
+++ b/spec/serializers/activitypub/note_serializer_spec.rb
@@ -22,14 +22,7 @@
       'contentMap' => include({
         'zh-TW' => a_kind_of(String),
       }),
-      'context' => include(
-        'type' => 'Collection',
-        'first' => include(
-          'type' => 'CollectionPage',
-          'items' => include(parent.uri, reply_by_account_first.uri, reply_by_account_next.uri,
-                             reply_by_account_third.uri, reply_by_other_first.uri)
-        )
-      ),
+      'context' => ActivityPub::TagManager.instance.uri_for(parent.conversation),
       'replies' => replies_collection_values,
     })
   end

From 2358f4b6f0b99075f174d707ba148cf95ecd0fc3 Mon Sep 17 00:00:00 2001
From: Jesse Karmani <jessekarmani@gmail.com>
Date: Mon, 13 Jan 2025 14:40:13 -0800
Subject: [PATCH 4/7] Set attributedTo for conversation context when
 serializing to ActivityPub format

---
 app/serializers/activitypub/context_serializer.rb | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/app/serializers/activitypub/context_serializer.rb b/app/serializers/activitypub/context_serializer.rb
index 19ebe5b088d87b..fcefc2718106ee 100644
--- a/app/serializers/activitypub/context_serializer.rb
+++ b/app/serializers/activitypub/context_serializer.rb
@@ -3,7 +3,7 @@
 class ActivityPub::ContextSerializer < ActivityPub::Serializer
   include RoutingHelper
 
-  attributes :id, :type, :first
+  attributes :id, :type, :first, :attributed_to
 
   has_one :first, serializer: ActivityPub::CollectionSerializer
 
@@ -11,6 +11,10 @@ def id
     ActivityPub::TagManager.instance.uri_for(object)
   end
 
+  def attributed_to
+    ActivityPub::TagManager.instance.uri_for(object.parent_account)
+  end
+
   def type
     'Collection'
   end

From ea5a64901d6f4ae23f807817c325a13f0789cafc Mon Sep 17 00:00:00 2001
From: Jesse Karmani <jessekarmani@gmail.com>
Date: Tue, 14 Jan 2025 14:31:43 -0800
Subject: [PATCH 5/7] Fix status show throwing an authorization error for
 public statuses

This was introduced by the circles feature code cherry-picked from fedibird
---
 app/controllers/statuses_controller.rb | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/app/controllers/statuses_controller.rb b/app/controllers/statuses_controller.rb
index 4ce021ed4254e8..eaeaff078a76c1 100644
--- a/app/controllers/statuses_controller.rb
+++ b/app/controllers/statuses_controller.rb
@@ -59,7 +59,7 @@ def set_link_headers
   def set_status
     @status = @account.statuses.find(params[:id])
 
-    if request.authorization.present? && request.authorization.match(/^Bearer /i)
+    if !@status.distributable? && request.authorization.present? && request.authorization.match(/^Bearer /i)
       raise Mastodon::NotPermittedError unless @status.capability_tokens.find_by(token: request.authorization.gsub(/^Bearer /i, ''))
     else
       authorize @status, :show?

From d7fc6ed89d7a1f21864708b492cf619728a37deb Mon Sep 17 00:00:00 2001
From: Jesse Karmani <jessekarmani@gmail.com>
Date: Tue, 14 Jan 2025 16:33:43 -0800
Subject: [PATCH 6/7] Don't require an account for context activitypub
 endpoints

---
 app/controllers/activitypub/contexts_controller.rb | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/app/controllers/activitypub/contexts_controller.rb b/app/controllers/activitypub/contexts_controller.rb
index 786c0db82d48b3..8bd15eb3c244d2 100644
--- a/app/controllers/activitypub/contexts_controller.rb
+++ b/app/controllers/activitypub/contexts_controller.rb
@@ -18,6 +18,10 @@ def items
 
   private
 
+  def account_required?
+    false
+  end
+
   def set_conversation
     @conversation = Conversation.local.find(params[:id])
   end

From cc7c221df08c3a5b204f5c0cc7124981b3d6c8a4 Mon Sep 17 00:00:00 2001
From: Jesse Karmani <jessekarmani@gmail.com>
Date: Wed, 12 Mar 2025 13:13:38 -0700
Subject: [PATCH 7/7] Use filtered items to check for next page in ActivityPub
 context

---
 .../activitypub/contexts_controller.rb        |  6 +--
 .../activitypub/context_serializer.rb         |  7 +++-
 .../activitypub/contexts_controller_spec.rb   | 42 +++++++++++++++++++
 spec/fabricators/conversation_fabricator.rb   |  4 +-
 4 files changed, 54 insertions(+), 5 deletions(-)
 create mode 100644 spec/controllers/activitypub/contexts_controller_spec.rb

diff --git a/app/controllers/activitypub/contexts_controller.rb b/app/controllers/activitypub/contexts_controller.rb
index 8bd15eb3c244d2..eaeb91d29a2e1c 100644
--- a/app/controllers/activitypub/contexts_controller.rb
+++ b/app/controllers/activitypub/contexts_controller.rb
@@ -36,7 +36,7 @@ def items_collection_presenter
       type: :unordered,
       part_of: context_items_url(@conversation),
       next: next_page,
-      items: @conversation.statuses.map { |status| status.local? ? status : status.uri }
+      items: @items.map { |status| status.local? ? status : status.uri }
     )
 
     return page if page_requested?
@@ -53,9 +53,9 @@ def page_requested?
   end
 
   def next_page
-    return nil if @conversation.statuses.size < DESCENDANTS_LIMIT
+    return nil if @items.size < DESCENDANTS_LIMIT
 
-    context_items_url(@conversation, page: true, min_id: @conversation.statuses.last.id)
+    context_items_url(@conversation, page: true, min_id: @items.last.id)
   end
 
   def page_params
diff --git a/app/serializers/activitypub/context_serializer.rb b/app/serializers/activitypub/context_serializer.rb
index fcefc2718106ee..e5bd3b1ea26d9f 100644
--- a/app/serializers/activitypub/context_serializer.rb
+++ b/app/serializers/activitypub/context_serializer.rb
@@ -24,12 +24,17 @@ def first
     last_status = conversation_statuses.last
     conversation_statuses = conversation_statuses.pluck(:id, :uri)
     last_id = conversation_statuses.last&.first
+    has_more = object.statuses.count > ActivityPub::ContextsController::DESCENDANTS_LIMIT
+
+    next_page = if has_more
+                  last_id ? ActivityPub::TagManager.instance.context_uri_for(last_status, page: true, min_id: last_id) : ActivityPub::TagManager.instance.context_uri_for(last_status, page: true, only_other_accounts: true)
+                end
 
     ActivityPub::CollectionPresenter.new(
       type: :unordered,
       part_of: ActivityPub::TagManager.instance.uri_for(object),
       items: conversation_statuses.map(&:second),
-      next: last_id ? ActivityPub::TagManager.instance.context_uri_for(last_status, page: true, min_id: last_id) : ActivityPub::TagManager.instance.context_uri_for(last_status, page: true, only_other_accounts: true)
+      next: next_page
     )
   end
 end
diff --git a/spec/controllers/activitypub/contexts_controller_spec.rb b/spec/controllers/activitypub/contexts_controller_spec.rb
new file mode 100644
index 00000000000000..fa4eba0f829ae4
--- /dev/null
+++ b/spec/controllers/activitypub/contexts_controller_spec.rb
@@ -0,0 +1,42 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe ActivityPub::ContextsController do
+  let(:user) { Fabricate(:user) }
+  let(:conversation) { Fabricate(:conversation) }
+
+  before do
+    allow(controller).to receive(:signed_request_actor).and_return(nil)
+  end
+
+  describe 'GET #show' do
+    context 'with few statuses' do
+      before do
+        3.times do
+          Fabricate(:status, visibility: :private, account: user.account, conversation: conversation)
+        end
+      end
+
+      it 'does not include a next page link' do
+        get :show, params: { id: conversation.id }
+        json = JSON.parse(response.body)
+        expect(json['first']['next']).to be_nil
+      end
+    end
+
+    context 'with many statuses' do
+      before do
+        (ActivityPub::ContextsController::DESCENDANTS_LIMIT + 1).times do
+          Fabricate(:status, visibility: :private, account: user.account, conversation: conversation)
+        end
+      end
+
+      it 'includes a next page link' do
+        get :show, params: { id: conversation.id }
+        json = JSON.parse(response.body)
+        expect(json['first']['next']).to_not be_nil
+      end
+    end
+  end
+end
diff --git a/spec/fabricators/conversation_fabricator.rb b/spec/fabricators/conversation_fabricator.rb
index 5440e4380c72d9..2d3f98c037b2ba 100644
--- a/spec/fabricators/conversation_fabricator.rb
+++ b/spec/fabricators/conversation_fabricator.rb
@@ -1,3 +1,5 @@
 # frozen_string_literal: true
 
-Fabricator(:conversation)
+Fabricator(:conversation) do
+  parent_account { Fabricate(:account) }
+end