Start and end balance anchors for historical account balances (#2455)

* Add kind field to valuation

* Fix schema conflict

* Add kind to valuation

* Scaffold opening balance manager

* Opening balance manager implementation

* Update account import to use opening balance manager + tests

* Update account to use opening balance manager

* Fix test assertions, usage of current balance manager

* Lint fixes

* Add Opening Balance manager, add tests to forward calculator

* Add credit card to "all cash" designation

* Simplify valuation model

* Add current balance manager with tests

* Add current balance logic to reverse calculator and plaid sync

* Tweaks to initial calc logic

* Ledger testing helper, tweak assertions for reverse calculator

* Update test assertions

* Extract balance transformer, simplify calculators

* Algo simplifications

* Final tweaks to calculators

* Cleanup

* Fix error, propagate sync errors up to parent

* Update migration script, valuation naming

test/models/account/current_balance_manager_test.rb

@@ -0,0 +1,153 @@
+require "test_helper"
+
+class Account::CurrentBalanceManagerTest < ActiveSupport::TestCase
+  setup do
+    @connected_account = accounts(:connected)  # Connected account - can update current balance
+    @manual_account = accounts(:depository)  # Manual account - cannot update current balance
+  end
+
+  test "when no existing anchor, creates new anchor" do
+    manager = Account::CurrentBalanceManager.new(@connected_account)
+
+    assert_difference -> { @connected_account.entries.count } => 1,
+                     -> { @connected_account.valuations.count } => 1 do
+      result = manager.set_current_balance(1000)
+
+      assert result.success?
+      assert result.changes_made?
+      assert_nil result.error
+    end
+
+    current_anchor = @connected_account.valuations.current_anchor.first
+    assert_not_nil current_anchor
+    assert_equal 1000, current_anchor.entry.amount
+    assert_equal "current_anchor", current_anchor.kind
+
+    entry = current_anchor.entry
+    assert_equal 1000, entry.amount
+    assert_equal Date.current, entry.date
+    assert_equal "Current balance", entry.name  # Depository type returns "Current balance"
+  end
+
+  test "updates existing anchor" do
+    # First create a current anchor
+    manager = Account::CurrentBalanceManager.new(@connected_account)
+    result = manager.set_current_balance(1000)
+    assert result.success?
+
+    current_anchor = @connected_account.valuations.current_anchor.first
+    original_id = current_anchor.id
+    original_entry_id = current_anchor.entry.id
+
+    # Travel to tomorrow to ensure date change
+    travel_to Date.current + 1.day do
+      # Now update it
+      assert_no_difference -> { @connected_account.entries.count } do
+        assert_no_difference -> { @connected_account.valuations.count } do
+          result = manager.set_current_balance(2000)
+          assert result.success?
+          assert result.changes_made?
+        end
+      end
+
+      current_anchor.reload
+      assert_equal original_id, current_anchor.id # Same valuation record
+      assert_equal original_entry_id, current_anchor.entry.id # Same entry record
+      assert_equal 2000, current_anchor.entry.amount
+      assert_equal Date.current, current_anchor.entry.date # Should be updated to current date
+    end
+  end
+
+  test "when manual account, raises InvalidOperation error" do
+    manager = Account::CurrentBalanceManager.new(@manual_account)
+
+    error = assert_raises(Account::CurrentBalanceManager::InvalidOperation) do
+      manager.set_current_balance(1000)
+    end
+
+    assert_equal "Manual accounts cannot set current balance anchor. Set opening balance or use a reconciliation instead.", error.message
+
+    # Verify no current anchor was created
+    assert_nil @manual_account.valuations.current_anchor.first
+  end
+
+  test "when no changes made, returns success with no changes made" do
+    # First create a current anchor
+    manager = Account::CurrentBalanceManager.new(@connected_account)
+    result = manager.set_current_balance(1000)
+    assert result.success?
+    assert result.changes_made?
+
+    # Try to set the same value on the same date
+    result = manager.set_current_balance(1000)
+
+    assert result.success?
+    assert_not result.changes_made?
+    assert_nil result.error
+  end
+
+  test "updates only amount when balance changes" do
+    manager = Account::CurrentBalanceManager.new(@connected_account)
+
+    # Create initial anchor
+    result = manager.set_current_balance(1000)
+    assert result.success?
+
+    current_anchor = @connected_account.valuations.current_anchor.first
+    original_date = current_anchor.entry.date
+
+    # Update only the balance
+    result = manager.set_current_balance(1500)
+    assert result.success?
+    assert result.changes_made?
+
+    current_anchor.reload
+    assert_equal 1500, current_anchor.entry.amount
+    assert_equal original_date, current_anchor.entry.date # Date should remain the same if on same day
+  end
+
+  test "updates date when called on different day" do
+    manager = Account::CurrentBalanceManager.new(@connected_account)
+
+    # Create initial anchor
+    result = manager.set_current_balance(1000)
+    assert result.success?
+
+    current_anchor = @connected_account.valuations.current_anchor.first
+    original_amount = current_anchor.entry.amount
+
+    # Travel to tomorrow and update with same balance
+    travel_to Date.current + 1.day do
+      result = manager.set_current_balance(1000)
+      assert result.success?
+      assert result.changes_made? # Should be true because date changed
+
+      current_anchor.reload
+      assert_equal original_amount, current_anchor.entry.amount
+      assert_equal Date.current, current_anchor.entry.date # Should be updated to new current date
+    end
+  end
+
+  test "current_balance returns balance from current anchor" do
+    manager = Account::CurrentBalanceManager.new(@connected_account)
+
+    # Create a current anchor
+    manager.set_current_balance(1500)
+
+    # Should return the anchor's balance
+    assert_equal 1500, manager.current_balance
+
+    # Update the anchor
+    manager.set_current_balance(2500)
+
+    # Should return the updated balance
+    assert_equal 2500, manager.current_balance
+  end
+
+  test "current_balance falls back to account balance when no anchor exists" do
+    manager = Account::CurrentBalanceManager.new(@connected_account)
+
+    # When no current anchor exists, should fall back to account.balance
+    assert_equal @connected_account.balance, manager.current_balance
+  end
+end