fix(bank-integration): validate required Excel columns per Amount Mode

Importing into Mode 3 with a preset that had no Amount mapping silently
dropped every row and showed a confusing "No transactions found" message.
Two fixes:

- Preset.validate() now requires the Standard Fields the parser needs for
  the chosen mode (Mode 1: Date+Amount; Mode 2: Date+Debit+Credit; Mode 3:
  Date+Amount+Direction). Clear error on save lists exactly what's missing.
- When all rows drop due to unreadable amount, the import dialog now opens
  a helper modal pointing at the preset, instead of the generic empty
  message.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

jey_erp/jey_erp/doctype/bank_integration_excel_preset/bank_integration_excel_preset.py

@@ -6,11 +6,40 @@ from frappe import _
 from frappe.model.document import Document
 
 
+# Standard fields the parser needs depending on the chosen amount_mode.
+# Date is always required.
+_REQUIRED_BY_MODE = {
+	"Single column with sign": ("Date", "Amount"),
+	"Separate debit/credit columns": ("Date", "Debit", "Credit"),
+	"Single column + direction column": ("Date", "Amount", "Direction"),
+}
+
+
 class BankIntegrationExcelPreset(Document):
 	def validate(self):
-		if self.amount_mode == "Single column + direction column":
-			if not (self.direction_debit_values or "").strip() and not (self.direction_credit_values or "").strip():
-				frappe.throw(_(
-					"Mode 'Single column + direction column' requires at least one of "
-					"'Debit Values' or 'Credit Values' to be filled (comma-separated)."
-				))
+		self._validate_required_mappings()
+		self._validate_direction_values()
+
+	def _validate_required_mappings(self):
+		mode = self.amount_mode or "Separate debit/credit columns"
+		required = _REQUIRED_BY_MODE.get(mode, ())
+		mapped = {
+			(row.standard_field or "").strip()
+			for row in (self.column_mappings or [])
+			if row.excel_column and row.standard_field
+		}
+		missing = [f for f in required if f not in mapped]
+		if missing:
+			frappe.throw(_(
+				"Amount Mode '{0}' requires these Standard Fields to be mapped in the Column Mappings table: {1}. "
+				"Add a row for each missing field."
+			).format(mode, ", ".join(missing)))
+
+	def _validate_direction_values(self):
+		if self.amount_mode != "Single column + direction column":
+			return
+		if not (self.direction_debit_values or "").strip() and not (self.direction_credit_values or "").strip():
+			frappe.throw(_(
+				"Mode 'Single column + direction column' requires at least one of "
+				"'Debit Values' or 'Credit Values' to be filled (comma-separated)."
+			))

jey_erp/public/js/bank_transaction_list.js

@@ -128,13 +128,17 @@ const BIExcelImport = {
 					BIExcelImport._showDirectionHelp(droppedDirection, unknownDirections, values.preset);
 					return;
 				}
+				if (droppedAmount > 0 && !txns.length) {
+					BIExcelImport._showAmountHelp(droppedAmount, values.preset);
+					return;
+				}
 				if (!txns.length) {
 					frappe.msgprint({
 						title: __('Nothing to Import'),
 						indicator: 'blue',
 						message: skipped > 0
 							? __('All {0} parsed rows are duplicates.', [skipped])
-							: __('No transactions found in the file.'),
+							: __('No transactions found in the file. Check that the Header Row on the preset points at the actual header line.'),
 					});
 					return;
 				}
@@ -316,6 +320,29 @@ const BIExcelImport = {
 		d.show();
 	},
 
+	_showAmountHelp(droppedCount, presetName) {
+		const openPreset = function () {
+			frappe.set_route('Form', 'Bank Integration Excel Preset', presetName);
+		};
+		const d = new frappe.ui.Dialog({
+			title: __('Amount Column Missing or Empty'),
+			fields: [{
+				fieldtype: 'HTML',
+				options:
+					'<div class="alert alert-danger">' +
+					__('All {0} row(s) were dropped because the amount could not be read.', [droppedCount]) +
+					'</div>' +
+					'<p>' + __('Most likely the <b>Amount</b> column (or <b>Debit</b>/<b>Credit</b>, depending on Amount Mode) is not mapped to an Excel header in the preset.') + '</p>' +
+					'<p>' + __('Open the preset and check the Column Mappings table — Standard Field values must include all columns required by the chosen Amount Mode.') + '</p>',
+			}],
+			primary_action_label: __('Open Preset'),
+			primary_action() { d.hide(); openPreset(); },
+			secondary_action_label: __('Close'),
+			secondary_action() { d.hide(); },
+		});
+		d.show();
+	},
+
 	_showDirectionHelp(droppedCount, unknownDirections, presetName) {
 		const openPreset = function () {
 			frappe.set_route('Form', 'Bank Integration Excel Preset', presetName);