feat: resolve party at Create & Reconcile time from the mappings

A Bank Transaction created before its counterparty was mapped carries no
party. When reconciling, look up the BT's bank_party_name in the
customer/supplier mappings — if that counterparty is mapped to an
ERPNext party, the txn gets it, so counterparty-based rules match and
the created PE/JE carries the party. Also: only attach a party to a
Payment Entry when one of the GL accounts is Receivable/Payable
(otherwise ERPNext rejects it).

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

kapital_bank/mapping.py

@@ -37,6 +37,39 @@ def _extract_messages(message_log):
 	return " | ".join(p for p in parts if p)
 
 
+def _build_name_to_party(settings):
+	"""Counterparty text -> {"Customer": erp_customer} / {"Supplier": erp_supplier}."""
+	idx = {}
+	for row in settings.customer_mappings:
+		if not row.erp_customer or not row.kb_customer_name:
+			continue
+		cust_name = frappe.db.get_value("Kapital Bank Customer", row.kb_customer_name, "customer_name")
+		if cust_name:
+			idx.setdefault(cust_name.strip(), {})["Customer"] = row.erp_customer
+	for row in settings.supplier_mappings:
+		if not row.erp_supplier or not row.kb_supplier_name:
+			continue
+		supp_name = frappe.db.get_value("Kapital Bank Supplier", row.kb_supplier_name, "supplier_name")
+		if supp_name:
+			idx.setdefault(supp_name.strip(), {})["Supplier"] = row.erp_supplier
+	return idx
+
+
+def _resolve_party_from_name(name, name_to_party, payment_type):
+	"""(party_type, erp_party) for `name`, or (None, None). Prefers Customer for
+	incoming (Receive) and Supplier for outgoing (Pay), falling back to the other."""
+	cands = name_to_party.get((name or "").strip())
+	if not cands:
+		return None, None
+	preferred = "Customer" if payment_type == "Receive" else "Supplier"
+	other = "Supplier" if preferred == "Customer" else "Customer"
+	if preferred in cands:
+		return preferred, cands[preferred]
+	if other in cands:
+		return other, cands[other]
+	return None, None
+
+
 @frappe.whitelist()
 def create_purpose_mappings(transactions, paid_from=None, paid_to=None, document_type="Payment Entry", mode="Both"):
 	"""Bulk-create transaction mappings and/or documents from selected BRT transactions."""
@@ -57,6 +90,20 @@ def create_purpose_mappings(transactions, paid_from=None, paid_to=None, document
 		if needs_settings:
 			settings = frappe.get_single("Kapital Bank Settings")
 
+			# A Bank Transaction created before its counterparty was mapped has no
+			# party. Resolve it now, from the customer/supplier mappings, so both
+			# counterparty-based rule matching and the created PE/JE pick it up.
+			name_to_party = _build_name_to_party(settings)
+			for txn in txn_list:
+				if txn.get("party") or not txn.get("bank_transaction_name"):
+					continue
+				bp_name = frappe.db.get_value("Bank Transaction", txn["bank_transaction_name"], "bank_party_name")
+				payment_type = "Pay" if txn.get("drcr") == "D" else "Receive"
+				pt, ep = _resolve_party_from_name(bp_name, name_to_party, payment_type)
+				if pt and ep:
+					txn["party_type"] = pt
+					txn["party"] = ep
+
 		if mode in ("Both", "Mappings Only"):
 			existing_purpose = {
 				(row.purpose_keyword, row.payment_type, (row.currency or "").upper())
@@ -459,7 +506,12 @@ def _create_payment_entry_for_brt(txn, paid_from, paid_to, bank_txn):
 		pe.reference_no = bank_txn.reference_number or txn.get("reference_number") or ""
 		pe.reference_date = posting_date
 		pe.remarks = bank_txn.description or txn.get("purpose") or ""
+		# Only attach a party if one of the GL accounts is a party account —
+		# otherwise ERPNext rejects the PE ("Party Account ... is required").
 		if party_type and party:
+			pf_type = frappe.get_cached_value("Account", paid_from, "account_type") or ""
+			pt_type = frappe.get_cached_value("Account", paid_to, "account_type") or ""
+			if pf_type in ("Receivable", "Payable") or pt_type in ("Receivable", "Payable"):
 				pe.party_type = party_type
 				pe.party = party