dlv_account_reconciliation_rest_amount extends the bank reconciliation widget (Accounting → Reconciliation, model bank.rec.widget) so the still outstanding ("rest") amount of a partially matched line is shown in parentheses next to its total.

On the reconciliation screen, when an added invoice/bill (a new_aml line) is only partially used to close the statement line, Odoo shows the full source amount struck through below the amount actually used — but not what remains unmatched on that line. This addon adds that missing number, e.g.:

€ 1.899,97
€ 4.486,35   (€ 2.586,38)

so the user immediately sees that €2.586,38 of that invoice is still outstanding, without having to search for it elsewhere.

How it works

models/bank_rec_widget_line.py inherits bank.rec.widget.line and adds two computed Monetary fields, rest_debit and rest_credit (source_balance - balance, split like the existing debit/credit fields). Because bank.rec.widget._compute_lines_widget automatically serializes every field of bank.rec.widget.line to the front-end, these two fields become available client-side as line.rest_debit / line.rest_credit (each with .display, .value, .is_zero) with no extra plumbing needed.
static/src/xml/reconciliation_rest_amount.xml extends the OWL template account_accountant.bank_rec_widget_form_lines_widget (t-inherit-mode="extension") and prints the rest amount in parentheses next to the struck-through source amount, when it is non-zero.

Note on the bank movement itself

Earlier iterations of this addon assumed the bank movement (liquidity) line could also show a "rest" amount, based on the legacy (pre-16.4) reconciliation widget where that concept existed. In the bank.rec.widget model actually used on this instance, the liquidity line always reflects the full statement line amount — there is no partial/rest concept for it, so nothing is shown there. See ROADMAP.md.

Dependencies

account_accountant

Installation

Standard addon install/update (-u dlv_account_reconciliation_rest_amount). No configuration or data is added; the change is a new computed field plus a purely visual template extension on the existing reconciliation widget.