So how can that work for air seals? Have a big robust air storage that can replenish losses from your half-broken door? How many other systems like that do we need? And all that extra weight somehow doesn't get you stranded in space when your badly maintained, low efficiency engine can't move it and your payload with the fuel that fits in the tanks? I get the principle, it just seems literally impossible to achieve (without, maybe, a radical step forward from chemical propulsion).

Same way rusty old cargo ships keep the sea out. Redundancy. Compartments. Emergency doors that close. Crew that run around patching leaks. Spare parts and welding equipment.

The ISS leaks air on a daily basis.