[eirvandelden]

Summary

Amounts live in decimal columns, so half cents can enter the books through arithmetic such as splits and receipt lines. A half cent changes a total that a user sees, and no bank statement has one.

Every money amount is stored as a whole number of cents: what is 1,5 today becomes 150. Users still type and read 1,50 in the interface. No amount that a user sees goes up or down because of the change.

Implementation

New:

• app/models/cents.rb — Cents.parse, Cents.from_euros, Cents.to_euros.
• app/models/cents/type.rb — Cents::Type.
• app/models/concerns/monetary.rb — monetary macro and the unreadable-amount validation.
• app/helpers/money_helper.rb — cents_to_currency, cents_field_value.
• db/migrate/20261016120000_convert_money_to_cents.rb — the migration.
• test/models/cents_test.rb, test/models/cents/type_test.rb, test/models/concerns/monetary_test.rb, test/models/money_fixtures_test.rb, test/helpers/money_helper_test.rb, test/migrations/convert_money_to_cents_test.rb, test/integration/transaction_amounts_test.rb, test/tools/assistant/budget_status_test.rb.
• docs/changes/cents-instead-of-decimals/verify/dump_before.rb, verify/dump_after.rb, verify/dump_raw.sql — the real-data check scripts. They leave with the change folder at delivery.

Changed:

• db/schema.rb — ten columns become integer.
• Models: appropriation.rb, budget_category.rb, chattel.rb, receipt.rb, receipt_line.rb, transaction_split.rb, transaction.rb — include Monetary, monetary ..., numericality → comparison, search SQL, amount_was.to_i, return-type doc comments (@return [Integer] cents).
• app/models/concerns/splittable.rb, linkable.rb — doc comments to Integer cents; Cents.parse in searchable_transfers.
• app/models/budget.rb — suggested_amounts rounds to Integer cents.
• app/models/dashboard.rb — budget_amounts and historical_averages in Integer cents; doc comments.
• app/models/importing/ing/row.rb, app/models/importing/albert_heijn/packing_slip.rb — cents.
• Helpers: products_helper.rb (to_d division), todos_helper.rb (cents_to_currency).
• Views — every number_to_currency becomes cents_to_currency: appropriations/{index,show,_balance}, budgets/show, chattels/_table, dashboard/_balance, product_types/show, products/{show,_price_chart}, receipts/{index,show,_basket}, searches/_result_transaction, shared/_recent_transactions, transaction_links/{_balance_table,_search_results,_suggestions}, transaction_splits/_table, transactions/{_table,show}.
• Form fields get value: cents_field_value(...): appropriations/_form, budgets/_budget_category_fields, chattels/_form, transaction_splits/_table, transactions/_form.
• dashboard/index.html.erb — chart data converted to euros.
• transactions/_transaction.json.jbuilder — amount in euros.
• MCP tools: budget_status.rb, charge_to_appropriation.rb, find_uncategorized_transactions.rb, list_appropriations.rb, set_appropriation.rb, set_budget_amount.rb.
• Locales en.yml, nl.yml, it.yml — activerecord.errors.messages.not_an_amount (en "is not an amount", nl "is geen bedrag", it "non è un importo"); then bundle exec i18n-tasks normalize.
• test/fixtures/{appropriations,budget_categories,chattels,receipt_lines,receipts,transaction_splits,transactions}.yml — values in cents.
• Existing tests that use euro literals for money, across test/models, test/integration, test/helpers, test/jobs, test/tools, test/views, test/system (56 files mention an amount; only those whose literals or expectations break change). test/system/budgets_test.rb formats the expected field value with format("%.2f", Cents.to_euros(amount)).

Proof

• A transaction stored as 1,5 shows as 1,50 after the migration and as 150 in the database → test/migrations/convert_money_to_cents_test.rb "up stores a transaction of 1,5 as 150 cents" and test/integration/transaction_amounts_test.rb "a transaction of 150 cents shows as 1,50"
• A user who types 1,50 in the transaction form gets 150 stored and sees 1,50 again → test/integration/transaction_amounts_test.rb "typing 1,50 stores 150 cents and the form shows 1,50 again"
• A user who types 1,5 or 1.50 gets the same result → test/integration/transaction_amounts_test.rb "typing 1,5 or 1.50 stores 150 cents"
• A transaction of 12,34 split into 10,00 and 2,34 still sums to 12,34 and stays valid → test/integration/transaction_splits_test.rb "splitting 12,34 into 10,00 and 2,34 leaves nothing unsplit"
• A receipt with lines that add up to its total before the migration still adds up after it → test/migrations/convert_money_to_cents_test.rb "receipt lines that add up to the total still do after up"
• Budget totals and dashboard balances show the same figures before and after the migration → test/integration/dashboard_test.rb and test/integration/budgets_test.rb existing figure assertions, green on cent fixtures; and check: the real-data comparison below, dashboard and budget section
• The MCP tool for budget status still reports 12.50 for 1250 cents → test/tools/assistant/budget_status_test.rb "reports a plan of 1250 cents as 12.50"
• Rolling the migration back restores the original decimal values → test/migrations/convert_money_to_cents_test.rb "down restores the original decimal values"; and check: after the real-data run, bin/rails db:rollback, then sqlite3 storage/db/development.sqlite3 < docs/changes/cents-instead-of-decimals/verify/dump_raw.sql > tmp/raw_after_rollback.txt, and diff tmp/raw_before.txt tmp/raw_after_rollback.txt prints nothing. This raw dump needs no app code, so the branch's cent-based code cannot distort it. Migrate up again afterwards.