perf(transactions): add kind to Transaction model and remove expensive Transfer joins in aggregations (#2388)

* add kind to transaction model

* Basic transfer creator

* Fix method naming conflict

* Creator form pattern

* Remove stale methods

* Tweak migration

* Remove BaseQuery, write entire query in each class for clarity

* Query optimizations

* Remove unused exchange rate query lines

* Remove temporary cache-warming strategy

* Fix test

* Update transaction search

* Decouple transactions endpoint from IncomeStatement

* Clean up transactions controller

* Update cursor rules

* Cleanup comments, logic in search

* Fix totals logic on transactions view

* Fix pagination

* Optimize search totals query

* Default to last 30 days on transactions page if no filters

* Decouple transactions list from transfer details

* Revert transfer route

* Migration reset

* Bundle update

* Fix matching logic, tests

* Remove unused code

test/models/transfer/creator_test.rb

@@ -0,0 +1,166 @@
+require "test_helper"
+
+class Transfer::CreatorTest < ActiveSupport::TestCase
+  setup do
+    @family = families(:dylan_family)
+    @source_account = accounts(:depository)
+    @destination_account = accounts(:investment)
+    @date = Date.current
+    @amount = 100
+  end
+
+  test "creates basic transfer" do
+    creator = Transfer::Creator.new(
+      family: @family,
+      source_account_id: @source_account.id,
+      destination_account_id: @destination_account.id,
+      date: @date,
+      amount: @amount
+    )
+
+    transfer = creator.create
+
+    assert transfer.persisted?
+    assert_equal "confirmed", transfer.status
+    assert transfer.regular_transfer?
+    assert_equal "transfer", transfer.transfer_type
+
+    # Verify outflow transaction (from source account)
+    outflow = transfer.outflow_transaction
+    assert_equal "funds_movement", outflow.kind
+    assert_equal @amount, outflow.entry.amount
+    assert_equal @source_account.currency, outflow.entry.currency
+    assert_equal "Transfer to #{@destination_account.name}", outflow.entry.name
+
+    # Verify inflow transaction (to destination account)
+    inflow = transfer.inflow_transaction
+    assert_equal "funds_movement", inflow.kind
+    assert_equal(@amount * -1, inflow.entry.amount)
+    assert_equal @destination_account.currency, inflow.entry.currency
+    assert_equal "Transfer from #{@source_account.name}", inflow.entry.name
+  end
+
+  test "creates multi-currency transfer" do
+    # Use crypto account which has USD currency but different from source
+    crypto_account = accounts(:crypto)
+
+    creator = Transfer::Creator.new(
+      family: @family,
+      source_account_id: @source_account.id,
+      destination_account_id: crypto_account.id,
+      date: @date,
+      amount: @amount
+    )
+
+    transfer = creator.create
+
+    assert transfer.persisted?
+    assert transfer.regular_transfer?
+    assert_equal "transfer", transfer.transfer_type
+
+    # Verify outflow transaction
+    outflow = transfer.outflow_transaction
+    assert_equal "funds_movement", outflow.kind
+    assert_equal "Transfer to #{crypto_account.name}", outflow.entry.name
+
+    # Verify inflow transaction with currency handling
+    inflow = transfer.inflow_transaction
+    assert_equal "funds_movement", inflow.kind
+    assert_equal "Transfer from #{@source_account.name}", inflow.entry.name
+    assert_equal crypto_account.currency, inflow.entry.currency
+  end
+
+  test "creates loan payment" do
+    loan_account = accounts(:loan)
+
+    creator = Transfer::Creator.new(
+      family: @family,
+      source_account_id: @source_account.id,
+      destination_account_id: loan_account.id,
+      date: @date,
+      amount: @amount
+    )
+
+    transfer = creator.create
+
+    assert transfer.persisted?
+    assert transfer.loan_payment?
+    assert_equal "loan_payment", transfer.transfer_type
+
+    # Verify outflow transaction is marked as loan payment
+    outflow = transfer.outflow_transaction
+    assert_equal "loan_payment", outflow.kind
+    assert_equal "Payment to #{loan_account.name}", outflow.entry.name
+
+    # Verify inflow transaction
+    inflow = transfer.inflow_transaction
+    assert_equal "funds_movement", inflow.kind
+    assert_equal "Payment from #{@source_account.name}", inflow.entry.name
+  end
+
+  test "creates credit card payment" do
+    credit_card_account = accounts(:credit_card)
+
+    creator = Transfer::Creator.new(
+      family: @family,
+      source_account_id: @source_account.id,
+      destination_account_id: credit_card_account.id,
+      date: @date,
+      amount: @amount
+    )
+
+    transfer = creator.create
+
+    assert transfer.persisted?
+    assert transfer.liability_payment?
+    assert_equal "liability_payment", transfer.transfer_type
+
+    # Verify outflow transaction is marked as payment for liability
+    outflow = transfer.outflow_transaction
+    assert_equal "cc_payment", outflow.kind
+    assert_equal "Payment to #{credit_card_account.name}", outflow.entry.name
+
+    # Verify inflow transaction
+    inflow = transfer.inflow_transaction
+    assert_equal "funds_movement", inflow.kind
+    assert_equal "Payment from #{@source_account.name}", inflow.entry.name
+  end
+
+  test "raises error when source account ID is invalid" do
+    assert_raises(ActiveRecord::RecordNotFound) do
+      Transfer::Creator.new(
+        family: @family,
+        source_account_id: 99999,
+        destination_account_id: @destination_account.id,
+        date: @date,
+        amount: @amount
+      )
+    end
+  end
+
+  test "raises error when destination account ID is invalid" do
+    assert_raises(ActiveRecord::RecordNotFound) do
+      Transfer::Creator.new(
+        family: @family,
+        source_account_id: @source_account.id,
+        destination_account_id: 99999,
+        date: @date,
+        amount: @amount
+      )
+    end
+  end
+
+  test "raises error when source account belongs to different family" do
+    other_family = families(:empty)
+
+    assert_raises(ActiveRecord::RecordNotFound) do
+      Transfer::Creator.new(
+        family: other_family,
+        source_account_id: @source_account.id,
+        destination_account_id: @destination_account.id,
+        date: @date,
+        amount: @amount
+      )
+    end
+  end
+end