fix(manufacturing): prefer the phantom line as bom_stock_analysis representative

Address review on #56090: get_bom_data groups components by item_code, so it
picks one representative BOM Item line for the (bom_no, is_phantom_item) pair.
Taking the first line by idx dropped the phantom flag when a non-phantom line
was listed before the phantom one, so explode_phantom_boms skipped the sub-BOM.

Keep one row per item_code (preserving the qty_per_unit total per component
rather than widening the GROUP BY), but make the representative phantom-
preferring: the first line, upgraded to the first phantom line if any exists.
A phantom sub-BOM is therefore never dropped due to line order, on either engine.

Adds test_phantom_explosion_when_phantom_line_is_not_first (phantom line at
idx 2) alongside the existing idx-1 case; both pass on MariaDB and Postgres and
the new one fails on the naive first-line representative.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

erpnext/manufacturing/report/bom_stock_analysis/bom_stock_analysis.py

@@ -239,17 +239,21 @@ def get_bom_data(filters):
 		# bom_no + is_phantom_item drive whether/which sub-BOM explode_phantom_boms recurses into, so
 		# they must come from the SAME BOM Item line. Aggregating each independently (Max) could pair a
 		# bom_no from one line with is_phantom_item from another when an item_code repeats in the BOM.
-		# Take the first (lowest idx) line per item_code as the coherent representative.
-		first_line = {}
+		# Rows are grouped by item_code (one qty_per_unit total per component), so pick one coherent
+		# representative line: the first line, but upgrade to the first phantom line if any exists, so a
+		# phantom sub-BOM is never dropped just because a non-phantom line happens to be listed first.
+		representative = {}
 		for line in frappe.get_all(
 			"BOM Item",
 			filters={"parent": filters.get("bom"), "parenttype": "BOM"},
 			fields=["item_code", "bom_no", "is_phantom_item"],
 			order_by="idx",
 		):
-			first_line.setdefault(line.item_code, line)
+			existing = representative.get(line.item_code)
+			if existing is None or (line.is_phantom_item and not existing.is_phantom_item):
+				representative[line.item_code] = line
 		for row in data:
-			line = first_line.get(row.item_code)
+			line = representative.get(row.item_code)
 			if line:
 				row.bom_no = line.bom_no
 				row.is_phantom_item = line.is_phantom_item

erpnext/manufacturing/report/bom_stock_analysis/test_bom_stock_analysis.py

@@ -79,16 +79,10 @@ class TestBOMStockAnalysis(ERPNextTestSuite):
 		)
 		self.assertEqual(footer.get("description"), expected_min)
 
-	def test_phantom_explosion_picks_coherent_sub_bom(self):
-		"""bom_no and is_phantom_item must come from the SAME BOM Item line.
-
-		When a component is listed more than once in a BOM pointing at different sub-BOMs
-		(one phantom, one not), the report groups both lines into a single row by item_code.
-		Aggregating bom_no and is_phantom_item with independent Max() could pair the phantom
-		flag of one line with the bom_no of the other, so explode_phantom_boms recurses into
-		the wrong sub-BOM. We now take one coherent representative line (lowest idx), so the
-		phantom sub-BOM is the one exploded.
-		"""
+	def _build_duplicate_component_bom(self, phantom_first):
+		"""Parent BOM that lists one `component` twice, once via a phantom sub-BOM and once via a
+		non-phantom sub-BOM. `phantom_first` controls which line is at idx 1. Returns the names of
+		(parent_bom, rm_phantom, rm_normal, component)."""
 		rm_phantom = make_item(properties={"is_stock_item": 1, "valuation_rate": 10}).name
 		rm_normal = make_item(properties={"is_stock_item": 1, "valuation_rate": 10}).name
 		component = make_item(properties={"is_stock_item": 1, "valuation_rate": 10}).name
@@ -101,10 +95,12 @@ class TestBOMStockAnalysis(ERPNextTestSuite):
 		phantom_bom.submit()
 		normal_bom = make_bom(item=component, raw_materials=[rm_normal])
 
-		# Parent lists `component` twice: phantom line first (idx 1), non-phantom second (idx 2).
 		fg_item = make_item(properties={"is_stock_item": 1, "valuation_rate": 10}).name
+		first_bom, second_bom = (
+			(phantom_bom.name, normal_bom.name) if phantom_first else (normal_bom.name, phantom_bom.name)
+		)
 		parent = make_bom(item=fg_item, raw_materials=[component], do_not_save=True)
-		parent.items[0].bom_no = phantom_bom.name
+		parent.items[0].bom_no = first_bom
 		component_doc = frappe.get_doc("Item", component)
 		parent.append(
 			"items",
@@ -113,21 +109,43 @@ class TestBOMStockAnalysis(ERPNextTestSuite):
 				"qty": 1,
 				"uom": component_doc.stock_uom,
 				"stock_uom": component_doc.stock_uom,
-				"bom_no": normal_bom.name,
+				"bom_no": second_bom,
 			},
 		)
 		parent.save()
 		parent.submit()
+		return parent.name, rm_phantom, rm_normal, component
 
-		raw_data = bom_stock_analysis_report(filters={"qty_to_make": 1, "bom": parent.name})[1]
+	def _assert_phantom_exploded(self, parent_bom, rm_phantom, rm_normal, component):
+		raw_data = bom_stock_analysis_report(filters={"qty_to_make": 1, "bom": parent_bom})[1]
 		items = {row.get("item") for row in raw_data if row}
-
 		# Phantom sub-BOM exploded -> its raw material appears; the component row is replaced.
 		self.assertIn(rm_phantom, items)
 		self.assertNotIn(component, items)
 		# The non-phantom line's sub-BOM must NOT be mis-exploded.
 		self.assertNotIn(rm_normal, items)
 
+	def test_phantom_explosion_picks_coherent_sub_bom(self):
+		"""bom_no and is_phantom_item must come from the SAME BOM Item line.
+
+		When a component is listed more than once in a BOM pointing at different sub-BOMs
+		(one phantom, one not), the report groups both lines into a single row by item_code.
+		Aggregating bom_no and is_phantom_item with independent Max() could pair the phantom
+		flag of one line with the bom_no of the other, so explode_phantom_boms recurses into
+		the wrong sub-BOM. We now take one coherent representative line, so the phantom sub-BOM
+		is the one exploded.
+		"""
+		self._assert_phantom_exploded(*self._build_duplicate_component_bom(phantom_first=True))
+
+	def test_phantom_explosion_when_phantom_line_is_not_first(self):
+		"""The phantom flag must win regardless of line order.
+
+		If the non-phantom line is listed first (idx 1) and the phantom line second, a naive
+		first-line representative would drop the phantom flag and skip the sub-BOM explosion.
+		The representative is phantom-preferring, so the phantom sub-BOM is still exploded.
+		"""
+		self._assert_phantom_exploded(*self._build_duplicate_component_bom(phantom_first=False))
+
 
 def split_data_and_footer(raw_data):
 	"""Separate component rows from the footer row. Skips blank spacer rows."""