Does idling the engine for seven hours damage it?

This will not hurt the vehicle one time, but it is clearly not something you want to continue to do.

This engine is capable of running all day as many people do use if something that is running all day like mail carrier, construction workers, etc.

So it is capable of doing it but those engine require oil changes much more frequently. So if you are concerned about it, just change the oil much sooner then normal.

So if you are at 12,000 miles, you should have just done an oil change so I would do another one at 15,000 (assuming you are on 7,500 mile intervals) and then get back on your normal interval.

https://www.2carpros.com/articles/how-to-change-engine-oil-and-filter

The only thing you need to keep an eye on is oil consumption. I attached the info on this below but I suspect you will be just fine.

Please let us know if you have questions on this. Thanks