Fix CSV import with no currency (#462)

* FIX use the accounts we are importing currency as default, not family default

* FIX add family fallback for multi account import

app/models/import.rb

@@ -244,7 +244,7 @@ class Import < ApplicationRecord
     end
 
     def default_currency
-      family.currency
+      account&.currency || family.currency
     end
 
     def parsed_csv

app/models/mint_import.rb

@@ -29,11 +29,14 @@ class MintImport < Import
         category = mappings.categories.mappable_for(row.category)
         tags = row.tags_list.map { |tag| mappings.tags.mappable_for(tag) }.compact
 
+        # Use account's currency when no currency column was mapped in CSV, with family currency as fallback
+        effective_currency = currency_col_label.present? ? row.currency : (account.currency.presence || family.currency)
+
         entry = account.entries.build \
           date: row.date_iso,
           amount: row.signed_amount,
           name: row.name,
-          currency: row.currency,
+          currency: effective_currency,
           notes: row.notes,
           entryable: Transaction.new(category: category, tags: tags),
           import: self

app/models/transaction_import.rb

@@ -27,6 +27,9 @@ class TransactionImport < Import
         category = mappings.categories.mappable_for(row.category)
         tags = row.tags_list.map { |tag| mappings.tags.mappable_for(tag) }.compact
 
+        # Use account's currency when no currency column was mapped in CSV, with family currency as fallback
+        effective_currency = currency_col_label.present? ? row.currency : (mapped_account.currency.presence || family.currency)
+
         # Check for duplicate transactions using the adapter's deduplication logic
         # Pass claimed_entry_ids to exclude entries we've already matched in this import
         # This ensures identical rows within the CSV are all imported as separate transactions
@@ -34,7 +37,7 @@ class TransactionImport < Import
         duplicate_entry = adapter.find_duplicate_transaction(
           date: row.date_iso,
           amount: row.signed_amount,
-          currency: row.currency,
+          currency: effective_currency,
           name: row.name,
           exclude_entry_ids: claimed_entry_ids
         )
@@ -57,7 +60,7 @@ class TransactionImport < Import
               date: row.date_iso,
               amount: row.signed_amount,
               name: row.name,
-              currency: row.currency,
+              currency: effective_currency,
               notes: row.notes,
               import: self
             )

test/models/transaction_import_test.rb

@@ -277,6 +277,41 @@ class TransactionImportTest < ActiveSupport::TestCase
     ).count
   end
 
+  test "uses family currency as fallback when account has no currency and no CSV currency column" do
+    account = accounts(:depository)
+    family = account.family
+
+    # Clear the account's currency to simulate an account without currency set
+    account.update_column(:currency, nil)
+
+    import_csv = <<~CSV
+      date,name,amount
+      01/01/2024,Test Transaction,100
+    CSV
+
+    @import.update!(
+      account: account,
+      raw_file_str: import_csv,
+      date_col_label: "date",
+      amount_col_label: "amount",
+      name_col_label: "name",
+      date_format: "%m/%d/%Y",
+      amount_type_strategy: "signed_amount",
+      signage_convention: "inflows_negative"
+    )
+
+    @import.generate_rows_from_csv
+    @import.reload
+
+    assert_difference -> { Entry.count } => 1 do
+      @import.publish
+    end
+
+    # The transaction should have the family's currency as fallback
+    entry = @import.entries.first
+    assert_equal family.currency, entry.currency
+  end
+
   test "does not raise error when all accounts are properly mapped" do
     # Import CSV with multiple accounts, all mapped
     import_csv = <<~CSV