diff --git a/app/models/decklist.rb b/app/models/decklist.rb
index fbc93a9..55a5647 100644
--- a/app/models/decklist.rb
+++ b/app/models/decklist.rb
@@ -4,7 +4,7 @@
 #
 # Decklists are the public, published decklists owned by various users.
 class Decklist < ApplicationRecord
-  # TODO(plural): Add a relationship to a public user object.
+  belongs_to :user
   belongs_to :side
 
   has_one :identity_card, # rubocop:disable Rails/InverseOf
diff --git a/app/models/review.rb b/app/models/review.rb
index 903df0b..7258616 100644
--- a/app/models/review.rb
+++ b/app/models/review.rb
@@ -3,6 +3,7 @@
 # Model for reviews of cards.
 class Review < ApplicationRecord
   belongs_to :card
+  belongs_to :user, optional: true
   has_many :review_comments
   has_many :review_votes
 
diff --git a/app/models/review_comment.rb b/app/models/review_comment.rb
index 0909a19..3271c2c 100644
--- a/app/models/review_comment.rb
+++ b/app/models/review_comment.rb
@@ -3,4 +3,5 @@
 # Model for comments on reviews.
 class ReviewComment < ApplicationRecord
   belongs_to :review
+  belongs_to :user, optional: true
 end
diff --git a/app/models/review_vote.rb b/app/models/review_vote.rb
index 35741df..ed446cd 100644
--- a/app/models/review_vote.rb
+++ b/app/models/review_vote.rb
@@ -3,4 +3,5 @@
 # Model for votes on reviews.
 class ReviewVote < ApplicationRecord
   belongs_to :review
+  belongs_to :user, optional: true
 end
diff --git a/app/models/user.rb b/app/models/user.rb
index 77c464b..ad28d81 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -5,4 +5,8 @@
 # This object will remain fairly lean since user management will not be handled in the application itself.
 class User < ApplicationRecord
   has_many :decks
+  has_many :decklists
+  has_many :reviews
+  has_many :review_comments
+  has_many :review_votes
 end
diff --git a/db/migrate/20260520044700_add_missing_foreign_keys.rb b/db/migrate/20260520044700_add_missing_foreign_keys.rb
new file mode 100644
index 0000000..2ac37e3
--- /dev/null
+++ b/db/migrate/20260520044700_add_missing_foreign_keys.rb
@@ -0,0 +1,46 @@
+# frozen_string_literal: true
+
+class AddMissingForeignKeys < ActiveRecord::Migration[8.1]
+  def change
+    # User constraints
+    add_foreign_key :decklists, :users
+    add_foreign_key :reviews, :users
+    add_foreign_key :review_comments, :users
+    add_foreign_key :review_votes, :users
+
+    # card_faces constraints
+    add_foreign_key :card_faces, :cards
+
+    # card_faces_card_subtypes constraints
+    add_foreign_key :card_faces_card_subtypes, :card_subtypes
+
+    # Composite foreign key for card_faces_card_subtypes -> card_faces
+    reversible do |dir|
+      dir.up do
+        execute <<~SQL
+          ALTER TABLE card_faces_card_subtypes
+          ADD CONSTRAINT fk_card_faces_card_subtypes_card_faces
+          FOREIGN KEY (card_id, face_index)
+          REFERENCES card_faces (card_id, face_index);
+        SQL
+      end
+      dir.down do
+        execute <<~SQL
+          ALTER TABLE card_faces_card_subtypes
+          DROP CONSTRAINT fk_card_faces_card_subtypes_card_faces;
+        SQL
+      end
+    end
+
+    # illustrators_printings constraints
+    add_foreign_key :illustrators_printings, :illustrators
+    add_foreign_key :illustrators_printings, :printings
+
+    # printing_faces constraints
+    add_foreign_key :printing_faces, :printings
+
+    # printings_card_subtypes constraints
+    add_foreign_key :printings_card_subtypes, :printings
+    add_foreign_key :printings_card_subtypes, :card_subtypes
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index 8869ee7..613ffc6 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[8.1].define(version: 2026_05_09_183917) do
+ActiveRecord::Schema[8.1].define(version: 2026_05_20_044700) do
   # These are extensions that must be enabled in order to support this database
   enable_extension "pg_catalog.plpgsql"
   enable_extension "pgcrypto"
@@ -383,6 +383,9 @@
     t.datetime "updated_at", null: false
   end
 
+  add_foreign_key "card_faces", "cards"
+  add_foreign_key "card_faces_card_subtypes", "card_faces", column: ["card_id", "face_index"], primary_key: ["card_id", "face_index"], name: "fk_card_faces_card_subtypes_card_faces"
+  add_foreign_key "card_faces_card_subtypes", "card_subtypes"
   add_foreign_key "card_pools", "formats"
   add_foreign_key "card_pools_card_cycles", "card_cycles"
   add_foreign_key "card_pools_card_cycles", "card_pools"
@@ -400,6 +403,7 @@
   add_foreign_key "cards_card_subtypes", "cards"
   add_foreign_key "decklists", "cards", column: "identity_card_id"
   add_foreign_key "decklists", "sides"
+  add_foreign_key "decklists", "users"
   add_foreign_key "decklists_cards", "cards"
   add_foreign_key "decklists_cards", "decklists"
   add_foreign_key "decks", "cards", column: "identity_card_id"
@@ -408,8 +412,13 @@
   add_foreign_key "decks_cards", "cards"
   add_foreign_key "decks_cards", "decks"
   add_foreign_key "factions", "sides"
+  add_foreign_key "illustrators_printings", "illustrators"
+  add_foreign_key "illustrators_printings", "printings"
+  add_foreign_key "printing_faces", "printings"
   add_foreign_key "printings", "card_sets"
   add_foreign_key "printings", "cards"
+  add_foreign_key "printings_card_subtypes", "card_subtypes"
+  add_foreign_key "printings_card_subtypes", "printings"
   add_foreign_key "restrictions", "formats"
   add_foreign_key "restrictions_card_subtypes_banned", "card_subtypes"
   add_foreign_key "restrictions_card_subtypes_banned", "restrictions"
@@ -424,8 +433,11 @@
   add_foreign_key "restrictions_cards_universal_faction_cost", "cards"
   add_foreign_key "restrictions_cards_universal_faction_cost", "restrictions"
   add_foreign_key "review_comments", "reviews"
+  add_foreign_key "review_comments", "users"
   add_foreign_key "review_votes", "reviews"
+  add_foreign_key "review_votes", "users"
   add_foreign_key "reviews", "cards"
+  add_foreign_key "reviews", "users"
   add_foreign_key "rulings", "cards"
   add_foreign_key "snapshots", "card_pools"
   add_foreign_key "snapshots", "formats"