diff --git a/pos/migrations/v4.0_multi_branch.sql b/pos/migrations/v4.0_multi_branch.sql
index fb83f4a..4ea5850 100644
--- a/pos/migrations/v4.0_multi_branch.sql
+++ b/pos/migrations/v4.0_multi_branch.sql
@@ -230,6 +230,13 @@ ALTER TABLE cfdi_queue ALTER COLUMN sale_id DROP NOT NULL;
 CREATE OR REPLACE FUNCTION update_inventory_stock()
 RETURNS TRIGGER AS $$
 BEGIN
+    -- Skip operations that are not tied to a specific branch.
+    -- Per-branch stock tracking requires a branch_id; without it we can't
+    -- assign the stock to any location.
+    IF NEW.branch_id IS NULL THEN
+        RETURN NEW;
+    END IF;
+
     INSERT INTO inventory_stock (inventory_id, branch_id, stock)
     VALUES (NEW.inventory_id, NEW.branch_id, NEW.quantity)
     ON CONFLICT (inventory_id, branch_id) DO UPDATE
diff --git a/pos/services/pos_engine.py b/pos/services/pos_engine.py
index 9609791..86a2665 100644
--- a/pos/services/pos_engine.py
+++ b/pos/services/pos_engine.py
@@ -193,9 +193,23 @@ def process_sale(conn, sale_data):
     amount_paid = float(sale_data.get('amount_paid', 0))
     payment_details = sale_data.get('payment_details', [])
     notes = sale_data.get('notes')
-    branch_id = _safe_g('branch_id')
+    branch_id = sale_data.get('branch_id') or _safe_g('branch_id')
     employee_id = _safe_g('employee_id')
 
+    # Fallback to the main branch if none resolved (e.g. token without branch_id)
+    if not branch_id:
+        cur.execute("SELECT id FROM branches WHERE is_main = true AND is_active = true LIMIT 1")
+        row = cur.fetchone()
+        if row:
+            branch_id = row[0]
+        else:
+            cur.execute("SELECT id FROM branches WHERE is_active = true ORDER BY id LIMIT 1")
+            row = cur.fetchone()
+            branch_id = row[0] if row else None
+
+    if not branch_id:
+        raise ValueError("No hay sucursal activa disponible para registrar la venta")
+
     # ── Multi-currency support ───────────────────────────────────────────
     currency = sale_data.get('currency', 'MXN')
     if currency not in ('MXN', 'USD'):