Covers the silently-regressable money + classification bits of the re-bill
flow (the maintainer's "thin CRM test coverage" concern). Pure functions via a
new expenseService._internal export — no DB, no date-harness pitfalls:
- computeMarkupMinor: percent rounding, flat, none/null.
- resolveMarkup precedence: override > expense clause > none.
- buildExpenseInsert: bad-disposition guard, tax_treatment/status defaults,
declined -> status+reason, markup field matches type, parked -> status.
11 tests, all green (npx jest expenseService.markup).