At CX doors are ALWAYS opened ( and closed ) by the ground staff from the outside.
Opening the doors from the inside while armed will blow the slide ( obviously )
Opening from the outside will disarm the slide if left armed and thus prevent and accidental activation.
The cabin crew give the ground staff a thumbs up via the door viewing window to confirm the door is in Manual. Before fully opening the ground staff ( if possible ) visually check the girt bar is not attached at the bottom of the door sill ( by cracking the door a little ) and on the Airbus check the warning light is not on.
This seems to work ok with CX.
The only time the door can be opened from the inside is with the Captains permission under exceptional circumstances and generally most Captains brief the ISM to do the opening. ( or indeed he does it himself )