From 6f9a8ff101dd0ce66b61d0c7b7742a171515caec Mon Sep 17 00:00:00 2001
From: Nabin Hait <nabinhait@gmail.com>
Date: Sun, 14 Jun 2026 20:32:56 +0530
Subject: [PATCH] fix: don't convert item margin on exchange rate refresh

Changing the transaction/posting date re-triggers the `currency` handler,
which fetches a fresh exchange rate and, whenever it differs from the
current one, divided every Amount-type item margin and Actual tax charge
by the new rate. `margin_rate_or_amount` is an amount in the transaction
currency, so dividing it is only meaningful when the document actually
switches currency; on a mere rate refresh it silently shrinks the margin
every time.

Track the currency the rendered document is denominated in and convert
margins/actual charges only on a real currency change, while still
updating `conversion_rate` so base amounts recalculate correctly.

Also remove the duplicated `currency()` override in quotation.js: it
re-ran the same fetch-and-convert block after `super.currency()` (double
converting margins) and lacked the `load_after_mapping` guard. The base
handler already covers Quotation via `transaction_date`.

Fixes #45210
---
 erpnext/public/js/controllers/transaction.js  | 18 +++++++++++++++--
 .../selling/doctype/quotation/quotation.js    | 20 -------------------
 2 files changed, 16 insertions(+), 22 deletions(-)

diff --git a/erpnext/public/js/controllers/transaction.js b/erpnext/public/js/controllers/transaction.js
index deaf50846de..5b52c1dd66e 100644
--- a/erpnext/public/js/controllers/transaction.js
+++ b/erpnext/public/js/controllers/transaction.js
@@ -600,6 +600,10 @@ erpnext.TransactionController = class TransactionController extends erpnext.taxe
 	refresh() {
 		erpnext.toggle_naming_series();
 		erpnext.hide_company(this.frm);
+		// Remember the currency the rendered document is denominated in, so that a
+		// real currency change can be told apart from a mere exchange rate refresh
+		// (e.g. triggered by a date change).
+		this._doc_currency = this.frm.doc.currency;
 		this.set_dynamic_labels();
 		this.setup_sms();
 		this.setup_quality_inspection();
@@ -1470,6 +1474,10 @@ erpnext.TransactionController = class TransactionController extends erpnext.taxe
 		let me = this;
 		this.set_dynamic_labels();
 		let company_currency = this.get_company_currency();
+		// Currency the stored margins/actual charges are denominated in, captured
+		// before this trigger updates the tracker for the next one.
+		let previous_currency = this._doc_currency;
+		this._doc_currency = this.frm.doc.currency;
 		// Added `load_after_mapping` to determine if document is loading after mapping from another doc
 		if (
 			this.frm.doc.currency &&
@@ -1482,8 +1490,14 @@ erpnext.TransactionController = class TransactionController extends erpnext.taxe
 				company_currency,
 				function (exchange_rate) {
 					if (exchange_rate != me.frm.doc.conversion_rate) {
-						me.set_margin_amount_based_on_currency(exchange_rate);
-						me.set_actual_charges_based_on_currency(exchange_rate);
+						// Margins and actual charges are amounts in the transaction
+						// currency; convert them only when the currency itself changed,
+						// not when just the exchange rate was refreshed (e.g. by a date
+						// change), otherwise the entered margin keeps shrinking.
+						if (previous_currency !== me.frm.doc.currency) {
+							me.set_margin_amount_based_on_currency(exchange_rate);
+							me.set_actual_charges_based_on_currency(exchange_rate);
+						}
 						me.frm.set_value("conversion_rate", exchange_rate);
 					}
 				}
diff --git a/erpnext/selling/doctype/quotation/quotation.js b/erpnext/selling/doctype/quotation/quotation.js
index 1e6c729b892..1968968f3c8 100644
--- a/erpnext/selling/doctype/quotation/quotation.js
+++ b/erpnext/selling/doctype/quotation/quotation.js
@@ -382,26 +382,6 @@ erpnext.selling.QuotationController = class QuotationController extends erpnext.
 		dialog.show();
 	}
 
-	currency() {
-		super.currency();
-		let me = this;
-		const company_currency = this.get_company_currency();
-		if (this.frm.doc.currency && this.frm.doc.currency !== company_currency) {
-			this.get_exchange_rate(
-				this.frm.doc.transaction_date,
-				this.frm.doc.currency,
-				company_currency,
-				function (exchange_rate) {
-					if (exchange_rate != me.frm.doc.conversion_rate) {
-						me.set_margin_amount_based_on_currency(exchange_rate);
-						me.set_actual_charges_based_on_currency(exchange_rate);
-						me.frm.set_value("conversion_rate", exchange_rate);
-					}
-				}
-			);
-		}
-	}
-
 	disable_customer_if_creating_from_opportunity(doc) {
 		if (doc.opportunity) {
 			this.frm.set_df_property("party_name", "read_only", 1);