changes

fusion_canada_post/models/fusion_cp_shipment.py

@@ -252,10 +252,23 @@ class FusionCpShipment(models.Model):
         }
 
     def _action_open_attachment(self, attachment):
-        """Open an attachment PDF in the browser viewer (new tab)."""
+        """Open an attachment for the operator.
+
+        Delegates to ir.attachment.action_fusion_preview when
+        fusion_pdf_preview is installed — PDFs render in the preview
+        dialog, anything else downloads. Falls back to the legacy
+        new-tab URL when the helper isn't available. See CLAUDE.md
+        "PDF Preview" for the contract.
+        """
         self.ensure_one()
         if not attachment:
             return False
+        if hasattr(attachment, 'action_fusion_preview'):
+            return attachment.action_fusion_preview(
+                title=attachment.name or 'Shipping Label',
+                model_name=self._name,
+                record_ids=self.id,
+            )
         return {
             'type': 'ir.actions.act_url',
             'url': '/web/content/%s?download=false' % attachment.id,