Simplify _should_bypass_set_qty_producing to check only manual_consumption and add a guard in write to prevent zeroing out consumed quantities for production components.

models/stock_move.py

@@ -5,17 +5,27 @@ class StockMove(models.Model):
 
     def _should_bypass_set_qty_producing(self):
         """
-        Prevent auto-update of consumed quantity if:
-        - The move already has a quantity set (partial consumption).
-        - The move is already picked.
+        Only bypass if explicitly flagged as manual consumption.
+        We rely on the write() method to set this flag and to block resets.
         """
-        if self.sudo().quantity > 0 or self.sudo().picked or self.sudo().manual_consumption:
+        if self.sudo().manual_consumption:
             return True
         return super()._should_bypass_set_qty_producing()
 
     def write(self, vals):
-        # Enforce manual usage flags if quantity is being set
+        # 1. Universal Zero-Guard: Block reset to 0 for MO components that have content
+        if 'quantity' in vals and vals['quantity'] == 0:
+            # We filter for moves that are components and have 'something' (qty or lines)
+            # and are NOT being cancelled/scrapped (check context or state if needed, but simple is better for now)
+            protected = self.filtered(lambda m: m.raw_material_production_id and (m.quantity > 0 or m.move_line_ids))
+            if protected:
+                # Remove quantity from vals to prevent reset
+                vals = dict(vals)
+                del vals['quantity']
+
+        # 2. Enforce flags for positive updates
         if 'quantity' in vals and vals['quantity'] > 0:
              vals['manual_consumption'] = True
              vals['picked'] = True
+
         return super().write(vals)