CreditMemosController with Index, Details, Create, Apply, and Void actions.
All business logic (atomic apply transaction, RemainingBalance cap,
customer.CreditBalance adjustment, auto-Paid invoice when BalanceDue hits zero)
mirrors the invoice-centric IssueCreditMemo/ApplyCredit/VoidCreditMemo actions in
InvoicesController but redirects back to the credit memo rather than an invoice.
Views: Index (stats bar, status+search filter, table), Details (two-col layout
with application history table and Bootstrap Apply/Void confirm modals),
Create (customer dropdown, amount, reason, notes, optional expiry).
Apply modal populates amount automatically from min(remaining credit,
invoice balance due) via credit-memo.js data-attribute wiring (no inline scripts).
Nav: Credit Memos added to Billing & Payments section in _Layout.
Build: 0 errors. Unit tests: 200/200.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
