From ea54330fb0afd575a499a7d4cc6ebe0ae4d071ff Mon Sep 17 00:00:00 2001
From: Martin-Alexander <martingianna@gmail.com>
Date: Wed, 16 Jul 2025 17:44:37 -0400
Subject: [PATCH 1/6] add support for add/remove_foreign_key and
 add/remove_reference

---
 .../adapter/migrations_modules/stable.rb      |  30 +++
 spec/chrono_model/adapter/migrations_spec.rb  | 187 ++++++++++++++++++
 spec/spec_helper.rb                           |   2 +
 .../matchers/foreign_key_constraint.rb        |  63 ++++++
 4 files changed, 282 insertions(+)
 create mode 100644 spec/support/matchers/foreign_key_constraint.rb

diff --git a/lib/chrono_model/adapter/migrations_modules/stable.rb b/lib/chrono_model/adapter/migrations_modules/stable.rb
index 7bb6a80f..cb90492c 100644
--- a/lib/chrono_model/adapter/migrations_modules/stable.rb
+++ b/lib/chrono_model/adapter/migrations_modules/stable.rb
@@ -33,6 +33,36 @@ def remove_index(table_name, column_name = nil, **options)
             on_history_schema { super }
           end
         end
+
+        def add_foreign_key(from_table, to_table, **options)
+          if is_chrono?(from_table) != is_chrono?(to_table)
+            return on_schema("#{TEMPORAL_SCHEMA},#{schema_search_path}") { super }
+          end
+
+          if is_chrono?(from_table)
+            return on_temporal_schema { super }
+          end
+
+          super
+        end
+
+        def remove_foreign_key(from_table, to_table = nil, **options)
+          if to_table.nil?
+            return super unless is_chrono?(from_table)
+
+            on_temporal_schema { super }
+          end
+
+          if is_chrono?(from_table) != is_chrono?(to_table)
+            return on_schema("#{TEMPORAL_SCHEMA},#{schema_search_path}") { super }
+          end
+
+          if is_chrono?(from_table)
+            return on_temporal_schema { super }
+          end
+
+          super
+        end
       end
     end
   end
diff --git a/spec/chrono_model/adapter/migrations_spec.rb b/spec/chrono_model/adapter/migrations_spec.rb
index 42d10b8d..d968a795 100644
--- a/spec/chrono_model/adapter/migrations_spec.rb
+++ b/spec/chrono_model/adapter/migrations_spec.rb
@@ -2,6 +2,7 @@
 
 require 'spec_helper'
 require 'support/adapter/structure'
+require 'support/time_machine/structure'
 
 # For the structure of these tables, please see spec/support/adabters/structure.rb.
 
@@ -40,6 +41,7 @@
   describe '.create_table' do
     context 'with temporal tables' do
       include_context 'with temporal tables'
+
       it_behaves_like 'temporal table'
     end
 
@@ -491,4 +493,189 @@
       it { is_expected.to have_columns([['foo', 'double precision']]) }
     end
   end
+
+  describe '.add_foreign_key' do
+    let(:columns) do
+      native = [%w[baz_id bigint], %w[bar_id bigint]]
+
+      def native.to_proc
+        proc { |t|
+          t.references :baz
+          t.references :bar
+        }
+      end
+
+      native
+    end
+
+    context 'with temporal tables' do
+      include_context 'with temporal tables'
+
+      it 'adds constraints on foreign keys for plain tables' do
+        adapter.add_foreign_key table, :bazs
+
+        expect(table).to have_temporal_foreign_key_constraint('bazs', 'public')
+      end
+
+      it 'adds constraints on foreign keys for other temporal tables' do
+        adapter.add_foreign_key table, :bars
+
+        expect(table).to have_temporal_foreign_key_constraint('bars', 'temporal')
+      end
+    end
+
+    context 'with plain tables' do
+      include_context 'with plain tables'
+
+      it 'adds constraints on foreign keys for other plain tables' do
+        adapter.add_foreign_key table, :bazs
+
+        expect(table).to have_foreign_key_constraint('bazs', 'public')
+      end
+
+      it 'adds constraints on foreign keys for temporal tables' do
+        adapter.add_foreign_key table, :bars
+
+        expect(table).to have_foreign_key_constraint('bars', 'temporal')
+      end
+    end
+  end
+
+  describe '.remove_foreign_key' do
+    context 'with temporal tables' do
+      include_context 'with temporal tables'
+
+      before do
+        adapter.add_reference table, :baz, foreign_key: true
+        adapter.add_reference table, :bar, foreign_key: true
+      end
+
+      it 'removes constraints on plain tables' do
+        adapter.remove_foreign_key table, :bazs
+
+        expect(table).not_to have_temporal_foreign_key_constraint('bazs', 'public')
+      end
+
+      it 'removes constraints on temporal tables' do
+        adapter.remove_foreign_key table, :bars
+
+        expect(table).not_to have_temporal_foreign_key_constraint('bars', 'temporal')
+      end
+    end
+
+    context 'with plain tables' do
+      include_context 'with plain tables'
+
+      before do
+        adapter.add_reference table, :baz, foreign_key: true
+        adapter.add_reference table, :bar, foreign_key: true
+      end
+
+      it 'removes constraints on plain tables' do
+        adapter.remove_foreign_key table, :bazs
+
+        expect(table).not_to have_foreign_key_constraint('bazs', 'public')
+      end
+
+      it 'removes constraints on temporal tables' do
+        adapter.remove_foreign_key table, :bars
+
+        expect(table).not_to have_foreign_key_constraint('bars', 'temporal')
+      end
+    end
+  end
+
+  describe '.add_reference' do
+    context 'with temporal tables' do
+      include_context 'with temporal tables'
+
+      context 'to plain tables' do
+        it 'adds a foreign key and a constraint' do
+          adapter.add_reference table, :baz, foreign_key: true
+
+          expect(table).to have_columns([%w[baz_id bigint]])
+          expect(table).to have_temporal_foreign_key_constraint('bazs', 'public')
+        end
+      end
+
+      context 'to other temporal tables' do
+        it 'adds a foreign key and a constraint' do
+          adapter.add_reference table, :bar, foreign_key: true
+
+          expect(table).to have_columns([%w[bar_id bigint]])
+          expect(table).to have_temporal_foreign_key_constraint('bars', 'temporal')
+        end
+      end
+    end
+
+    context 'with plain tables' do
+      include_context 'with plain tables'
+
+      context 'to other plain tables' do
+        it 'adds a foreign key and a constraint' do
+          adapter.add_reference table, :baz, foreign_key: true
+
+          expect(table).to have_columns([%w[baz_id bigint]])
+          expect(table).to have_foreign_key_constraint('bazs', 'public')
+        end
+      end
+
+      context 'to temporal tables' do
+        it 'adds a foreign key and a constraint' do
+          adapter.add_reference table, :bar, foreign_key: true
+
+          expect(table).to have_columns([%w[bar_id bigint]])
+          expect(table).to have_foreign_key_constraint('bars', 'temporal')
+        end
+      end
+    end
+  end
+
+  describe '.remove_reference' do
+    context 'with temporal tables' do
+      include_context 'with temporal tables'
+
+      before do
+        adapter.add_reference table, :baz, foreign_key: true
+        adapter.add_reference table, :bar, foreign_key: true
+      end
+
+      it 'removes the foreign key and constraint from plain tables' do
+        adapter.remove_reference table, :baz
+
+        expect(table).not_to have_columns([%w[baz_id bigint]])
+        expect(table).not_to have_temporal_foreign_key_constraint('bazs', 'public')
+      end
+
+      it 'removes the foreign key and constraint from other temporal tables' do
+        adapter.remove_reference table, :bar
+
+        expect(table).not_to have_columns([%w[bar_id bigint]])
+        expect(table).not_to have_temporal_foreign_key_constraint('bars', 'temporal')
+      end
+    end
+
+    context 'with plain tables' do
+      include_context 'with plain tables'
+
+      before do
+        adapter.add_reference table, :baz, foreign_key: true
+        adapter.add_reference table, :bar, foreign_key: true
+      end
+
+      it 'removes the foreign key and constraint from other plain tables' do
+        adapter.remove_reference table, :baz
+
+        expect(table).not_to have_columns([%w[baz_id bigint]])
+        expect(table).not_to have_foreign_key_constraint('bazs', 'public')
+      end
+
+      it 'removes the foreign key and constraint from temporal tables' do
+        adapter.remove_reference table, :bar
+
+        expect(table).not_to have_columns([%w[bar_id bigint]])
+        expect(table).not_to have_foreign_key_constraint('bars', 'temporal')
+      end
+    end
+  end
 end
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index 5dd06ada..624b7e70 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -14,6 +14,7 @@
 require_relative 'support/matchers/column'
 require_relative 'support/matchers/function'
 require_relative 'support/matchers/index'
+require_relative 'support/matchers/foreign_key_constraint'
 require_relative 'support/matchers/schema'
 require_relative 'support/matchers/source'
 require_relative 'support/matchers/table'
@@ -40,6 +41,7 @@
   config.include(ChronoTest::Matchers::Column)
   config.include(ChronoTest::Matchers::Function)
   config.include(ChronoTest::Matchers::Index)
+  config.include(ChronoTest::Matchers::ForeignKeyConstraint)
   config.include(ChronoTest::Matchers::Schema)
   config.include(ChronoTest::Matchers::Source)
   config.include(ChronoTest::Matchers::Table)
diff --git a/spec/support/matchers/foreign_key_constraint.rb b/spec/support/matchers/foreign_key_constraint.rb
new file mode 100644
index 00000000..44539679
--- /dev/null
+++ b/spec/support/matchers/foreign_key_constraint.rb
@@ -0,0 +1,63 @@
+# frozen_string_literal: true
+
+require_relative 'base'
+
+module ChronoTest
+  module Matchers
+    module ForeignKeyConstraint
+      class HaveForeignKeyConstraint < ChronoTest::Matchers::Base
+        attr_reader :ref_table, :ref_schema, :schema
+
+        def initialize(ref_table, ref_schema, schema = 'public')
+          @ref_table = ref_table
+          @ref_schema = ref_schema
+          @schema   = schema
+        end
+
+        def description
+          'have foreign key constraint'
+        end
+
+        def matches?(table)
+          super
+
+          select_values(<<~SQL.squish, [table, schema, ref_table, ref_schema], 'Check foreign key constraint').any?
+            SELECT 1
+              FROM pg_constraint c
+              JOIN pg_class t ON c.conrelid = t.oid
+              JOIN pg_class r ON c.confrelid = r.oid
+              JOIN pg_namespace tn ON t.relnamespace = tn.oid
+              JOIN pg_namespace rn ON r.relnamespace = rn.oid
+            WHERE t.relname = ?
+              AND tn.nspname = ?
+              AND r.relname = ?
+              AND rn.nspname = ?
+              AND c.contype = 'f';
+          SQL
+        end
+
+        def failure_message
+          "expected #{schema}.#{table} to have a foreign key constraint on #{ref_schema}#{ref_table}"
+        end
+
+        def failure_message_when_negated
+          "expected #{schema}.#{table} to not have a foreign key constraint on #{ref_schema}.#{ref_table}"
+        end
+      end
+
+      def have_foreign_key_constraint(*args)
+        HaveForeignKeyConstraint.new(*args)
+      end
+
+      class HaveTemporalForeignKeyConstraint < HaveForeignKeyConstraint
+        def initialize(ref_table, ref_schema)
+          super(ref_table, ref_schema, temporal_schema)
+        end
+      end
+
+      def have_temporal_foreign_key_constraint(*args)
+        HaveTemporalForeignKeyConstraint.new(*args)
+      end
+    end
+  end
+end

From a004ec3557c88a2befe425b04af1a9b6addb0e35 Mon Sep 17 00:00:00 2001
From: Martin-Alexander <martingianna@gmail.com>
Date: Fri, 18 Jul 2025 01:07:03 -0400
Subject: [PATCH 2/6] add support for foreign keys in create_table and
 implement better method of tracking original schema

---
 lib/chrono_model/adapter.rb                   |  26 +++-
 lib/chrono_model/adapter/migrations.rb        |  17 +++
 .../adapter/migrations_modules/stable.rb      |  30 ++--
 spec/chrono_model/adapter/base_spec.rb        |  22 +++
 spec/chrono_model/adapter/migrations_spec.rb  | 128 ++++++++++++++++++
 .../matchers/foreign_key_constraint.rb        |   2 +-
 6 files changed, 206 insertions(+), 19 deletions(-)

diff --git a/lib/chrono_model/adapter.rb b/lib/chrono_model/adapter.rb
index afdfee69..9e670c9a 100644
--- a/lib/chrono_model/adapter.rb
+++ b/lib/chrono_model/adapter.rb
@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 
 require 'active_record/connection_adapters/postgresql_adapter'
+require 'active_record/connection_adapters/postgresql/utils.rb'
 
 require_relative 'adapter/migrations'
 require_relative 'adapter/migrations_modules/stable'
@@ -112,13 +113,18 @@ def on_history_schema(&block)
 
     # Evaluates the given block in the given +schema+ search path.
     #
-    # Recursion works by saving the old_path the function closure
+    # Recursion works by saving the old_path in the method closure
     # at each recursive call.
     #
+    # @original_schema is set to the current schema on the first call,
+    # and restored to +nil+ when the recursion ends. Use outer_schema()
+    # to get the original schema.
+    #
     # See specs for examples and behaviour.
     #
     def on_schema(schema, recurse: :follow)
       old_path = schema_search_path
+      @original_schema ||= current_schema
 
       count_recursions do
         if (recurse == :follow) || (Thread.current['recursions'] == 1)
@@ -144,6 +150,24 @@ def on_schema(schema, recurse: :follow)
       else
         self.schema_search_path = old_path
       end
+
+      @original_schema = nil if Thread.current['recursions'] == 0
+    end
+
+    # The current schema or the schema that was the current schema before
+    # on_schema() was called.
+    #
+    def outer_schema
+      @original_schema || current_schema
+    end
+
+    # Implementation copied from a private method in
+    # ActiveRecord::ConnectionAdapters::PostgreSQL::SchemaStatements of
+    # the same name
+    #
+    def extract_schema_and_table(string)
+      name = ActiveRecord::ConnectionAdapters::PostgreSQL::Utils.extract_schema_qualified_name(string.to_s)
+      [name.schema, name.identifier]
     end
 
     # Returns true if the given name references a temporal table.
diff --git a/lib/chrono_model/adapter/migrations.rb b/lib/chrono_model/adapter/migrations.rb
index 7145aa39..219c331e 100644
--- a/lib/chrono_model/adapter/migrations.rb
+++ b/lib/chrono_model/adapter/migrations.rb
@@ -171,6 +171,23 @@ def remove_column(table_name, column_name, type = nil, **options)
         drop_and_recreate_public_view(table_name) { super }
       end
 
+      def build_create_table_definition(table_name, id: :primary_key, primary_key: nil, force: nil, **options)
+        table_definition = super
+
+        table_definition.foreign_keys.map! do |fk|
+          to_table_schema, _ = extract_schema_and_table(fk.to_table)
+
+          if to_table_schema.nil? && is_chrono?(fk.to_table) != !!options[:temporal]
+            schema = is_chrono?(fk.to_table) ? TEMPORAL_SCHEMA : outer_schema
+            fk.to_table = "#{schema}.#{fk.to_table}"
+          end
+
+          fk
+        end
+
+        table_definition
+      end
+
       private
 
       # In destructive changes, such as removing columns or changing column
diff --git a/lib/chrono_model/adapter/migrations_modules/stable.rb b/lib/chrono_model/adapter/migrations_modules/stable.rb
index cb90492c..d625f6a0 100644
--- a/lib/chrono_model/adapter/migrations_modules/stable.rb
+++ b/lib/chrono_model/adapter/migrations_modules/stable.rb
@@ -35,33 +35,29 @@ def remove_index(table_name, column_name = nil, **options)
         end
 
         def add_foreign_key(from_table, to_table, **options)
-          if is_chrono?(from_table) != is_chrono?(to_table)
-            return on_schema("#{TEMPORAL_SCHEMA},#{schema_search_path}") { super }
-          end
+          to_table_schema, _ = extract_schema_and_table(to_table)
 
-          if is_chrono?(from_table)
-            return on_temporal_schema { super }
+          if to_table_schema.nil? && is_chrono?(to_table) != is_chrono?(from_table)
+            schema = is_chrono?(to_table) ? TEMPORAL_SCHEMA : outer_schema
+            to_table = "#{schema}.#{to_table}"
           end
 
-          super
+          return super unless is_chrono?(from_table)
+
+          on_temporal_schema { super }
         end
 
         def remove_foreign_key(from_table, to_table = nil, **options)
-          if to_table.nil?
-            return super unless is_chrono?(from_table)
-
-            on_temporal_schema { super }
-          end
+          to_table_schema, _ = extract_schema_and_table(to_table)
 
-          if is_chrono?(from_table) != is_chrono?(to_table)
-            return on_schema("#{TEMPORAL_SCHEMA},#{schema_search_path}") { super }
+          if to_table_schema.nil? && is_chrono?(to_table) != is_chrono?(from_table)
+            schema = is_chrono?(to_table) ? TEMPORAL_SCHEMA : outer_schema
+            to_table = "#{schema}.#{to_table}"
           end
 
-          if is_chrono?(from_table)
-            return on_temporal_schema { super }
-          end
+          return super unless is_chrono?(from_table)
 
-          super
+          on_temporal_schema { super }
         end
       end
     end
diff --git a/spec/chrono_model/adapter/base_spec.rb b/spec/chrono_model/adapter/base_spec.rb
index 7a9b6409..0b99d582 100644
--- a/spec/chrono_model/adapter/base_spec.rb
+++ b/spec/chrono_model/adapter/base_spec.rb
@@ -108,6 +108,28 @@
     end
   end
 
+  describe '.outer_schema' do
+    subject(:outer_schema) { adapter.outer_schema }
+
+    context 'when outside of on_schema()' do
+      it { is_expected.to eq(adapter.current_schema) }
+    end
+
+    context 'when inside on_schema()' do
+      around do |example|
+        @original_schema = adapter.current_schema
+
+        adapter.on_schema('test_schema') do
+          example.run
+        end
+      end
+
+      it 'returns the original schema' do
+        expect(outer_schema).to eq(@original_schema)
+      end
+    end
+  end
+
   describe '.is_chrono?' do
     subject(:is_chrono?) { adapter.is_chrono?(table) }
 
diff --git a/spec/chrono_model/adapter/migrations_spec.rb b/spec/chrono_model/adapter/migrations_spec.rb
index d968a795..c482f254 100644
--- a/spec/chrono_model/adapter/migrations_spec.rb
+++ b/spec/chrono_model/adapter/migrations_spec.rb
@@ -43,12 +43,84 @@
       include_context 'with temporal tables'
 
       it_behaves_like 'temporal table'
+
+      context 'using t.references to temporal tables' do
+        let(:columns) do
+          native = [['bar_id', 'bigint']]
+
+          def native.to_proc
+            proc { |t| t.references :bar, foreign_key: true }
+          end
+
+          native
+        end
+
+        it_behaves_like 'temporal table'
+
+        it 'creates a foreign key constraint to the temporal schema' do
+          expect(table).to have_temporal_foreign_key_constraint('bars', 'temporal')
+        end
+      end
+
+      context 'using t.references to plain tables' do
+        let(:columns) do
+          native = [['baz_id', 'bigint']]
+
+          def native.to_proc
+            proc { |t| t.references :baz, foreign_key: true }
+          end
+
+          native
+        end
+
+        it_behaves_like 'temporal table'
+
+        it 'creates a foreign key constraint to the public schema' do
+          expect(table).to have_temporal_foreign_key_constraint('bazs', 'public')
+        end
+      end
     end
 
     context 'with plain tables' do
       include_context 'with plain tables'
 
       it_behaves_like 'plain table'
+
+      context 'using t.references to temporal tables' do
+        let(:columns) do
+          native = [['bar_id', 'bigint']]
+
+          def native.to_proc
+            proc { |t| t.references :bar, foreign_key: true }
+          end
+
+          native
+        end
+
+        it_behaves_like 'plain table'
+
+        it 'creates a foreign key constraint to the temporal schema' do
+          expect(table).to have_foreign_key_constraint('bars', 'temporal')
+        end
+      end
+
+      context 'using t.references to plain tables' do
+        let(:columns) do
+          native = [['baz_id', 'bigint']]
+
+          def native.to_proc
+            proc { |t| t.references :baz, foreign_key: true }
+          end
+
+          native
+        end
+
+        it_behaves_like 'plain table'
+
+        it 'creates a foreign key constraint to the public schema' do
+          expect(table).to have_foreign_key_constraint('bazs', 'public')
+        end
+      end
     end
   end
 
@@ -116,6 +188,34 @@
         it { is_expected.to have_temporal_columns([%w[new_column integer]]) }
         it { is_expected.to have_history_columns([%w[new_column integer]]) }
       end
+
+      context 'using t.references to temporal tables' do
+        before do
+          adapter.change_table table do |t|
+            t.references :bar, foreign_key: true
+          end
+        end
+
+        it_behaves_like 'temporal table'
+
+        it 'creates a foreign key constraint to the temporal schema' do
+          expect(table).to have_temporal_foreign_key_constraint('bars', 'temporal')
+        end
+      end
+
+      context 'using t.references to plain tables' do
+        before do
+          adapter.change_table table do |t|
+            t.references :baz, foreign_key: true
+          end
+        end
+
+        it_behaves_like 'temporal table'
+
+        it 'creates a foreign key constraint to the public schema' do
+          expect(table).to have_temporal_foreign_key_constraint('bazs', 'public')
+        end
+      end
     end
 
     context 'with plain tables' do
@@ -176,6 +276,34 @@
           expect(indexes - history_indexes.map(&:name).sort).to be_empty
         end
       end
+
+      context 'when using t.references to temporal tables' do
+        before do
+          adapter.change_table table do |t|
+            t.references :bar, foreign_key: true
+          end
+        end
+
+        it_behaves_like 'plain table'
+
+        it 'creates a foreign key constraint to the temporal schema' do
+          expect(table).to have_foreign_key_constraint('bars', 'temporal')
+        end
+      end
+
+      context 'when using t.references to plain tables' do
+        before do
+          adapter.change_table table do |t|
+            t.references :baz, foreign_key: true
+          end
+        end
+
+        it_behaves_like 'plain table'
+
+        it 'creates a foreign key constraint to the public schema' do
+          expect(table).to have_foreign_key_constraint('bazs', 'public')
+        end
+      end
     end
 
     # https://github.com/ifad/chronomodel/issues/91
diff --git a/spec/support/matchers/foreign_key_constraint.rb b/spec/support/matchers/foreign_key_constraint.rb
index 44539679..43f53e3f 100644
--- a/spec/support/matchers/foreign_key_constraint.rb
+++ b/spec/support/matchers/foreign_key_constraint.rb
@@ -37,7 +37,7 @@ def matches?(table)
         end
 
         def failure_message
-          "expected #{schema}.#{table} to have a foreign key constraint on #{ref_schema}#{ref_table}"
+          "expected #{schema}.#{table} to have a foreign key constraint on #{ref_schema}.#{ref_table}"
         end
 
         def failure_message_when_negated

From d43f05a0ff15830c356689ed6fbb8619cdef45ea Mon Sep 17 00:00:00 2001
From: Martin-Alexander <martingianna@gmail.com>
Date: Fri, 18 Jul 2025 01:48:52 -0400
Subject: [PATCH 3/6] addressed some rubocop offenses

---
 lib/chrono_model/adapter.rb                   |   4 +-
 lib/chrono_model/adapter/migrations.rb        |   2 +-
 .../adapter/migrations_modules/stable.rb      |   4 +-
 spec/chrono_model/adapter/base_spec.rb        |  10 +-
 spec/chrono_model/adapter/migrations_spec.rb  | 125 +++++++-----------
 .../matchers/foreign_key_constraint.rb        |   2 +-
 6 files changed, 57 insertions(+), 90 deletions(-)

diff --git a/lib/chrono_model/adapter.rb b/lib/chrono_model/adapter.rb
index 9e670c9a..82dbc44d 100644
--- a/lib/chrono_model/adapter.rb
+++ b/lib/chrono_model/adapter.rb
@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 require 'active_record/connection_adapters/postgresql_adapter'
-require 'active_record/connection_adapters/postgresql/utils.rb'
+require 'active_record/connection_adapters/postgresql/utils'
 
 require_relative 'adapter/migrations'
 require_relative 'adapter/migrations_modules/stable'
@@ -151,7 +151,7 @@ def on_schema(schema, recurse: :follow)
         self.schema_search_path = old_path
       end
 
-      @original_schema = nil if Thread.current['recursions'] == 0
+      @original_schema = nil if Thread.current['recursions'].zero?
     end
 
     # The current schema or the schema that was the current schema before
diff --git a/lib/chrono_model/adapter/migrations.rb b/lib/chrono_model/adapter/migrations.rb
index 219c331e..3a76242d 100644
--- a/lib/chrono_model/adapter/migrations.rb
+++ b/lib/chrono_model/adapter/migrations.rb
@@ -175,7 +175,7 @@ def build_create_table_definition(table_name, id: :primary_key, primary_key: nil
         table_definition = super
 
         table_definition.foreign_keys.map! do |fk|
-          to_table_schema, _ = extract_schema_and_table(fk.to_table)
+          to_table_schema, = extract_schema_and_table(fk.to_table)
 
           if to_table_schema.nil? && is_chrono?(fk.to_table) != !!options[:temporal]
             schema = is_chrono?(fk.to_table) ? TEMPORAL_SCHEMA : outer_schema
diff --git a/lib/chrono_model/adapter/migrations_modules/stable.rb b/lib/chrono_model/adapter/migrations_modules/stable.rb
index d625f6a0..7373f019 100644
--- a/lib/chrono_model/adapter/migrations_modules/stable.rb
+++ b/lib/chrono_model/adapter/migrations_modules/stable.rb
@@ -35,7 +35,7 @@ def remove_index(table_name, column_name = nil, **options)
         end
 
         def add_foreign_key(from_table, to_table, **options)
-          to_table_schema, _ = extract_schema_and_table(to_table)
+          to_table_schema, = extract_schema_and_table(to_table)
 
           if to_table_schema.nil? && is_chrono?(to_table) != is_chrono?(from_table)
             schema = is_chrono?(to_table) ? TEMPORAL_SCHEMA : outer_schema
@@ -48,7 +48,7 @@ def add_foreign_key(from_table, to_table, **options)
         end
 
         def remove_foreign_key(from_table, to_table = nil, **options)
-          to_table_schema, _ = extract_schema_and_table(to_table)
+          to_table_schema, = extract_schema_and_table(to_table)
 
           if to_table_schema.nil? && is_chrono?(to_table) != is_chrono?(from_table)
             schema = is_chrono?(to_table) ? TEMPORAL_SCHEMA : outer_schema
diff --git a/spec/chrono_model/adapter/base_spec.rb b/spec/chrono_model/adapter/base_spec.rb
index 0b99d582..7296677d 100644
--- a/spec/chrono_model/adapter/base_spec.rb
+++ b/spec/chrono_model/adapter/base_spec.rb
@@ -116,17 +116,13 @@
     end
 
     context 'when inside on_schema()' do
-      around do |example|
-        @original_schema = adapter.current_schema
+      it 'returns the original schema' do
+        original_schema = adapter.current_schema
 
         adapter.on_schema('test_schema') do
-          example.run
+          expect(outer_schema).to eq(original_schema)
         end
       end
-
-      it 'returns the original schema' do
-        expect(outer_schema).to eq(@original_schema)
-      end
     end
   end
 
diff --git a/spec/chrono_model/adapter/migrations_spec.rb b/spec/chrono_model/adapter/migrations_spec.rb
index c482f254..3189be2a 100644
--- a/spec/chrono_model/adapter/migrations_spec.rb
+++ b/spec/chrono_model/adapter/migrations_spec.rb
@@ -44,9 +44,9 @@
 
       it_behaves_like 'temporal table'
 
-      context 'using t.references to temporal tables' do
+      context 'when adding references to temporal tables' do
         let(:columns) do
-          native = [['bar_id', 'bigint']]
+          native = [%w[bar_id bigint]]
 
           def native.to_proc
             proc { |t| t.references :bar, foreign_key: true }
@@ -62,9 +62,9 @@ def native.to_proc
         end
       end
 
-      context 'using t.references to plain tables' do
+      context 'when adding references to plain tables' do
         let(:columns) do
-          native = [['baz_id', 'bigint']]
+          native = [%w[baz_id bigint]]
 
           def native.to_proc
             proc { |t| t.references :baz, foreign_key: true }
@@ -86,9 +86,9 @@ def native.to_proc
 
       it_behaves_like 'plain table'
 
-      context 'using t.references to temporal tables' do
+      context 'when adding references to temporal tables' do
         let(:columns) do
-          native = [['bar_id', 'bigint']]
+          native = [%w[bar_id bigint]]
 
           def native.to_proc
             proc { |t| t.references :bar, foreign_key: true }
@@ -104,9 +104,9 @@ def native.to_proc
         end
       end
 
-      context 'using t.references to plain tables' do
+      context 'when adding references to plain tables' do
         let(:columns) do
-          native = [['baz_id', 'bigint']]
+          native = [%w[baz_id bigint]]
 
           def native.to_proc
             proc { |t| t.references :baz, foreign_key: true }
@@ -189,7 +189,7 @@ def native.to_proc
         it { is_expected.to have_history_columns([%w[new_column integer]]) }
       end
 
-      context 'using t.references to temporal tables' do
+      context 'when adding references to temporal tables' do
         before do
           adapter.change_table table do |t|
             t.references :bar, foreign_key: true
@@ -203,7 +203,7 @@ def native.to_proc
         end
       end
 
-      context 'using t.references to plain tables' do
+      context 'when adding references to plain tables' do
         before do
           adapter.change_table table do |t|
             t.references :baz, foreign_key: true
@@ -277,7 +277,7 @@ def native.to_proc
         end
       end
 
-      context 'when using t.references to temporal tables' do
+      context 'when when adding references to temporal tables' do
         before do
           adapter.change_table table do |t|
             t.references :bar, foreign_key: true
@@ -291,7 +291,7 @@ def native.to_proc
         end
       end
 
-      context 'when using t.references to plain tables' do
+      context 'when when adding references to plain tables' do
         before do
           adapter.change_table table do |t|
             t.references :baz, foreign_key: true
@@ -623,29 +623,18 @@ def native.to_proc
   end
 
   describe '.add_foreign_key' do
-    let(:columns) do
-      native = [%w[baz_id bigint], %w[bar_id bigint]]
-
-      def native.to_proc
-        proc { |t|
-          t.references :baz
-          t.references :bar
-        }
-      end
-
-      native
-    end
-
     context 'with temporal tables' do
       include_context 'with temporal tables'
 
-      it 'adds constraints on foreign keys for plain tables' do
+      it 'adds foreign key constraints on plain tables' do
+        adapter.add_reference table, :baz, foreign_key: false
         adapter.add_foreign_key table, :bazs
 
         expect(table).to have_temporal_foreign_key_constraint('bazs', 'public')
       end
 
-      it 'adds constraints on foreign keys for other temporal tables' do
+      it 'adds foreign key constraints on other temporal tables' do
+        adapter.add_reference table, :bar, foreign_key: false
         adapter.add_foreign_key table, :bars
 
         expect(table).to have_temporal_foreign_key_constraint('bars', 'temporal')
@@ -655,13 +644,15 @@ def native.to_proc
     context 'with plain tables' do
       include_context 'with plain tables'
 
-      it 'adds constraints on foreign keys for other plain tables' do
+      it 'adds foreign key constraints on other plain tables' do
+        adapter.add_reference table, :baz, foreign_key: false
         adapter.add_foreign_key table, :bazs
 
         expect(table).to have_foreign_key_constraint('bazs', 'public')
       end
 
-      it 'adds constraints on foreign keys for temporal tables' do
+      it 'adds foreign key constraints on temporal tables' do
+        adapter.add_reference table, :bar, foreign_key: false
         adapter.add_foreign_key table, :bars
 
         expect(table).to have_foreign_key_constraint('bars', 'temporal')
@@ -673,18 +664,15 @@ def native.to_proc
     context 'with temporal tables' do
       include_context 'with temporal tables'
 
-      before do
+      it 'removes foreign key constraints on plain tables' do
         adapter.add_reference table, :baz, foreign_key: true
-        adapter.add_reference table, :bar, foreign_key: true
-      end
-
-      it 'removes constraints on plain tables' do
         adapter.remove_foreign_key table, :bazs
 
         expect(table).not_to have_temporal_foreign_key_constraint('bazs', 'public')
       end
 
-      it 'removes constraints on temporal tables' do
+      it 'removes foreign key constraints on other temporal tables' do
+        adapter.add_reference table, :bar, foreign_key: true
         adapter.remove_foreign_key table, :bars
 
         expect(table).not_to have_temporal_foreign_key_constraint('bars', 'temporal')
@@ -694,18 +682,15 @@ def native.to_proc
     context 'with plain tables' do
       include_context 'with plain tables'
 
-      before do
+      it 'removes foreign key constraint on other plain tables' do
         adapter.add_reference table, :baz, foreign_key: true
-        adapter.add_reference table, :bar, foreign_key: true
-      end
-
-      it 'removes constraints on plain tables' do
         adapter.remove_foreign_key table, :bazs
 
         expect(table).not_to have_foreign_key_constraint('bazs', 'public')
       end
 
-      it 'removes constraints on temporal tables' do
+      it 'removes foreign key constraints on temporal tables' do
+        adapter.add_reference table, :bar, foreign_key: true
         adapter.remove_foreign_key table, :bars
 
         expect(table).not_to have_foreign_key_constraint('bars', 'temporal')
@@ -717,44 +702,36 @@ def native.to_proc
     context 'with temporal tables' do
       include_context 'with temporal tables'
 
-      context 'to plain tables' do
-        it 'adds a foreign key and a constraint' do
-          adapter.add_reference table, :baz, foreign_key: true
+      it 'adds a foreign key column and constraint to plain tables' do
+        adapter.add_reference table, :baz, foreign_key: true
 
-          expect(table).to have_columns([%w[baz_id bigint]])
-          expect(table).to have_temporal_foreign_key_constraint('bazs', 'public')
-        end
+        expect(table).to have_columns([%w[baz_id bigint]])
+        expect(table).to have_temporal_foreign_key_constraint('bazs', 'public')
       end
 
-      context 'to other temporal tables' do
-        it 'adds a foreign key and a constraint' do
-          adapter.add_reference table, :bar, foreign_key: true
+      it 'adds a foreign key column and constraint to other temporal tables' do
+        adapter.add_reference table, :bar, foreign_key: true
 
-          expect(table).to have_columns([%w[bar_id bigint]])
-          expect(table).to have_temporal_foreign_key_constraint('bars', 'temporal')
-        end
+        expect(table).to have_columns([%w[bar_id bigint]])
+        expect(table).to have_temporal_foreign_key_constraint('bars', 'temporal')
       end
     end
 
     context 'with plain tables' do
       include_context 'with plain tables'
 
-      context 'to other plain tables' do
-        it 'adds a foreign key and a constraint' do
-          adapter.add_reference table, :baz, foreign_key: true
+      it 'adds a foreign key column and constraint to other plain tables' do
+        adapter.add_reference table, :baz, foreign_key: true
 
-          expect(table).to have_columns([%w[baz_id bigint]])
-          expect(table).to have_foreign_key_constraint('bazs', 'public')
-        end
+        expect(table).to have_columns([%w[baz_id bigint]])
+        expect(table).to have_foreign_key_constraint('bazs', 'public')
       end
 
-      context 'to temporal tables' do
-        it 'adds a foreign key and a constraint' do
-          adapter.add_reference table, :bar, foreign_key: true
+      it 'adds a foreign key column and constraint to temporal tables' do
+        adapter.add_reference table, :bar, foreign_key: true
 
-          expect(table).to have_columns([%w[bar_id bigint]])
-          expect(table).to have_foreign_key_constraint('bars', 'temporal')
-        end
+        expect(table).to have_columns([%w[bar_id bigint]])
+        expect(table).to have_foreign_key_constraint('bars', 'temporal')
       end
     end
   end
@@ -763,19 +740,16 @@ def native.to_proc
     context 'with temporal tables' do
       include_context 'with temporal tables'
 
-      before do
+      it 'removes the foreign key column and constraint from plain tables' do
         adapter.add_reference table, :baz, foreign_key: true
-        adapter.add_reference table, :bar, foreign_key: true
-      end
-
-      it 'removes the foreign key and constraint from plain tables' do
         adapter.remove_reference table, :baz
 
         expect(table).not_to have_columns([%w[baz_id bigint]])
         expect(table).not_to have_temporal_foreign_key_constraint('bazs', 'public')
       end
 
-      it 'removes the foreign key and constraint from other temporal tables' do
+      it 'removes the foreign key column and constraint from other temporal tables' do
+        adapter.add_reference table, :bar, foreign_key: true
         adapter.remove_reference table, :bar
 
         expect(table).not_to have_columns([%w[bar_id bigint]])
@@ -786,19 +760,16 @@ def native.to_proc
     context 'with plain tables' do
       include_context 'with plain tables'
 
-      before do
+      it 'removes the foreign key column and constraint from other plain tables' do
         adapter.add_reference table, :baz, foreign_key: true
-        adapter.add_reference table, :bar, foreign_key: true
-      end
-
-      it 'removes the foreign key and constraint from other plain tables' do
         adapter.remove_reference table, :baz
 
         expect(table).not_to have_columns([%w[baz_id bigint]])
         expect(table).not_to have_foreign_key_constraint('bazs', 'public')
       end
 
-      it 'removes the foreign key and constraint from temporal tables' do
+      it 'removes the foreign key column and constraint from temporal tables' do
+        adapter.add_reference table, :bar, foreign_key: true
         adapter.remove_reference table, :bar
 
         expect(table).not_to have_columns([%w[bar_id bigint]])
diff --git a/spec/support/matchers/foreign_key_constraint.rb b/spec/support/matchers/foreign_key_constraint.rb
index 43f53e3f..93b2a329 100644
--- a/spec/support/matchers/foreign_key_constraint.rb
+++ b/spec/support/matchers/foreign_key_constraint.rb
@@ -11,7 +11,7 @@ class HaveForeignKeyConstraint < ChronoTest::Matchers::Base
         def initialize(ref_table, ref_schema, schema = 'public')
           @ref_table = ref_table
           @ref_schema = ref_schema
-          @schema   = schema
+          @schema = schema
         end
 
         def description

From c35e9dae0577f4259c56277feec2d4908dcf7298 Mon Sep 17 00:00:00 2001
From: Martin-Alexander <martingianna@gmail.com>
Date: Sat, 19 Jul 2025 20:25:38 -0400
Subject: [PATCH 4/6] add support older versions of AR and slight refactor of
 schema modificationlogic

---
 lib/chrono_model/adapter.rb                   | 33 +++++++++++++++----
 lib/chrono_model/adapter/migrations.rb        | 17 ----------
 .../adapter/migrations_modules/stable.rb      | 14 +++-----
 3 files changed, 30 insertions(+), 34 deletions(-)

diff --git a/lib/chrono_model/adapter.rb b/lib/chrono_model/adapter.rb
index 82dbc44d..e4bf42f0 100644
--- a/lib/chrono_model/adapter.rb
+++ b/lib/chrono_model/adapter.rb
@@ -42,6 +42,20 @@ def initialize(*)
       end
     end
 
+    class TableDefinition < ActiveRecord::ConnectionAdapters::PostgreSQL::TableDefinition
+      def foreign_key(to_table, **options)
+        if !@conn.is_schema_qualified?(to_table) && (@conn.current_schema == TEMPORAL_SCHEMA) != @conn.is_chrono?(to_table)
+          to_table = @conn.qualified_table_name(to_table)
+        end
+
+        super
+      end
+    end
+
+    def create_table_definition(name, **options)
+      ChronoModel::Adapter::TableDefinition.new(self, name, **options)
+    end
+
     # Returns true whether the connection adapter supports our
     # implementation of temporal tables. Currently, Chronomodel
     # is supported starting with PostgreSQL 9.3 (90300 in PostgreSQL's
@@ -161,13 +175,18 @@ def outer_schema
       @original_schema || current_schema
     end
 
-    # Implementation copied from a private method in
-    # ActiveRecord::ConnectionAdapters::PostgreSQL::SchemaStatements of
-    # the same name
-    #
-    def extract_schema_and_table(string)
-      name = ActiveRecord::ConnectionAdapters::PostgreSQL::Utils.extract_schema_qualified_name(string.to_s)
-      [name.schema, name.identifier]
+    def foreign_key_column_for(table_name, *args) # :nodoc:
+      _schema, table_name = extract_schema_qualified_name(table_name)
+      super(table_name, *args)
+    end
+
+    def qualified_table_name(table_name)
+      schema = is_chrono?(table_name) ? TEMPORAL_SCHEMA : outer_schema
+      "#{schema}.#{table_name}"
+    end
+
+    def is_schema_qualified?(name)
+      name.to_s.include?('.')
     end
 
     # Returns true if the given name references a temporal table.
diff --git a/lib/chrono_model/adapter/migrations.rb b/lib/chrono_model/adapter/migrations.rb
index 3a76242d..7145aa39 100644
--- a/lib/chrono_model/adapter/migrations.rb
+++ b/lib/chrono_model/adapter/migrations.rb
@@ -171,23 +171,6 @@ def remove_column(table_name, column_name, type = nil, **options)
         drop_and_recreate_public_view(table_name) { super }
       end
 
-      def build_create_table_definition(table_name, id: :primary_key, primary_key: nil, force: nil, **options)
-        table_definition = super
-
-        table_definition.foreign_keys.map! do |fk|
-          to_table_schema, = extract_schema_and_table(fk.to_table)
-
-          if to_table_schema.nil? && is_chrono?(fk.to_table) != !!options[:temporal]
-            schema = is_chrono?(fk.to_table) ? TEMPORAL_SCHEMA : outer_schema
-            fk.to_table = "#{schema}.#{fk.to_table}"
-          end
-
-          fk
-        end
-
-        table_definition
-      end
-
       private
 
       # In destructive changes, such as removing columns or changing column
diff --git a/lib/chrono_model/adapter/migrations_modules/stable.rb b/lib/chrono_model/adapter/migrations_modules/stable.rb
index 7373f019..7d423036 100644
--- a/lib/chrono_model/adapter/migrations_modules/stable.rb
+++ b/lib/chrono_model/adapter/migrations_modules/stable.rb
@@ -35,11 +35,8 @@ def remove_index(table_name, column_name = nil, **options)
         end
 
         def add_foreign_key(from_table, to_table, **options)
-          to_table_schema, = extract_schema_and_table(to_table)
-
-          if to_table_schema.nil? && is_chrono?(to_table) != is_chrono?(from_table)
-            schema = is_chrono?(to_table) ? TEMPORAL_SCHEMA : outer_schema
-            to_table = "#{schema}.#{to_table}"
+          if !is_schema_qualified?(to_table) && is_chrono?(to_table) != is_chrono?(from_table)
+            to_table = qualified_table_name(to_table)
           end
 
           return super unless is_chrono?(from_table)
@@ -48,11 +45,8 @@ def add_foreign_key(from_table, to_table, **options)
         end
 
         def remove_foreign_key(from_table, to_table = nil, **options)
-          to_table_schema, = extract_schema_and_table(to_table)
-
-          if to_table_schema.nil? && is_chrono?(to_table) != is_chrono?(from_table)
-            schema = is_chrono?(to_table) ? TEMPORAL_SCHEMA : outer_schema
-            to_table = "#{schema}.#{to_table}"
+          if !is_schema_qualified?(to_table) && is_chrono?(to_table) != is_chrono?(from_table)
+            to_table = qualified_table_name(to_table)
           end
 
           return super unless is_chrono?(from_table)

From b173143b5d63b0773af036d5d95d7b672a900d28 Mon Sep 17 00:00:00 2001
From: Martin-Alexander <martingianna@gmail.com>
Date: Sat, 19 Jul 2025 20:29:56 -0400
Subject: [PATCH 5/6] remove unneccessary require

---
 lib/chrono_model/adapter.rb | 1 -
 1 file changed, 1 deletion(-)

diff --git a/lib/chrono_model/adapter.rb b/lib/chrono_model/adapter.rb
index e4bf42f0..37289321 100644
--- a/lib/chrono_model/adapter.rb
+++ b/lib/chrono_model/adapter.rb
@@ -1,7 +1,6 @@
 # frozen_string_literal: true
 
 require 'active_record/connection_adapters/postgresql_adapter'
-require 'active_record/connection_adapters/postgresql/utils'
 
 require_relative 'adapter/migrations'
 require_relative 'adapter/migrations_modules/stable'

From 89cbaeb4f32968a1243fe3a385c207eaaf6d6e23 Mon Sep 17 00:00:00 2001
From: Martin-Alexander <martingianna@gmail.com>
Date: Sat, 19 Jul 2025 20:30:16 -0400
Subject: [PATCH 6/6] fix style for super

---
 lib/chrono_model/adapter.rb | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/chrono_model/adapter.rb b/lib/chrono_model/adapter.rb
index 37289321..173cd5db 100644
--- a/lib/chrono_model/adapter.rb
+++ b/lib/chrono_model/adapter.rb
@@ -176,7 +176,7 @@ def outer_schema
 
     def foreign_key_column_for(table_name, *args) # :nodoc:
       _schema, table_name = extract_schema_qualified_name(table_name)
-      super(table_name, *args)
+      super
     end
 
     def qualified_table_name(table_name)