Clean watchers when losing access to board

https://app.fizzy.do/5986089/cards/2814

app/models/board/accessible.rb

@@ -45,6 +45,7 @@ module Board::Accessible
 
     mentions_for_user(user).destroy_all
     notifications_for_user(user).destroy_all
+    watches_for(user).destroy_all
   end
 
   def watchers
@@ -89,4 +90,8 @@ module Board::Accessible
               (notifications.source_type = 'Event' AND events.eventable_type = 'Comment' AND event_comment_cards.board_id = ?)",
                id, id)
     end
+
+    def watches_for(user)
+      Watch.where(card: cards, user: user)
+    end
 end

db/migrate/20251106154151_add_user_and_card_index_to_watches.rb

@@ -0,0 +1,5 @@
+class AddUserAndCardIndexToWatches < ActiveRecord::Migration[8.2]
+  def change
+    add_index :watches, %i[ user_id card_id ]
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[8.2].define(version: 2025_11_05_122933) do
+ActiveRecord::Schema[8.2].define(version: 2025_11_06_154151) do
   create_table "accesses", force: :cascade do |t|
     t.datetime "accessed_at"
     t.integer "board_id", null: false
@@ -404,6 +404,7 @@ ActiveRecord::Schema[8.2].define(version: 2025_11_05_122933) do
     t.integer "user_id", null: false
     t.boolean "watching", default: true, null: false
     t.index ["card_id"], name: "index_watches_on_card_id"
+    t.index ["user_id", "card_id"], name: "index_watches_on_user_id_and_card_id"
     t.index ["user_id"], name: "index_watches_on_user_id"
   end
 

db/schema_cache.yml

@@ -2760,6 +2760,23 @@ indexes:
     nulls_not_distinct:
     comment:
     valid: true
+  - !ruby/object:ActiveRecord::ConnectionAdapters::IndexDefinition
+    table: watches
+    name: index_watches_on_user_id_and_card_id
+    unique: false
+    columns:
+    - user_id
+    - card_id
+    lengths: {}
+    orders: {}
+    opclasses: {}
+    where:
+    type:
+    using:
+    include:
+    nulls_not_distinct:
+    comment:
+    valid: true
   webhook_delinquency_trackers:
   - !ruby/object:ActiveRecord::ConnectionAdapters::IndexDefinition
     table: webhook_delinquency_trackers
@@ -2843,4 +2860,4 @@ indexes:
     nulls_not_distinct:
     comment:
     valid: true
-version: 20251105122933
+version: 20251106154151

test/models/access_test.rb

@@ -64,4 +64,20 @@ class AccessTest < ActiveSupport::TestCase
 
     assert_empty remaining_mentions
   end
+
+  test "watches are destroyed when access is lost" do
+    kevin = users(:kevin)
+    board = boards(:writebook)
+    card = board.cards.first
+
+    assert card.watched_by?(kevin)
+
+    kevin_access = accesses(:writebook_kevin)
+
+    perform_enqueued_jobs only: Board::CleanInaccessibleDataJob do
+      kevin_access.destroy
+    end
+
+    assert_not card.watched_by?(kevin)
+  end
 end

test/models/board/accessible_test.rb

@@ -38,4 +38,6 @@ class Board::AccessibleTest < ActiveSupport::TestCase
     boards(:writebook).access_for(users(:kevin)).access_only!
     assert_not_includes boards(:writebook).reload.watchers, users(:kevin)
   end
+
+  # NOTE: The tests for clearing inaccessible data are in +AccessTest+
 end