Where does Arduino IDE store sketch meta-data?

I've started using Syncthing to share my sketchbook folder between my desktop and my laptop.

I was initially confused because I'd create a new sketch on my desktop, set the board to what I'm using, and then when I'd open it on the laptop, the board hadn't changed.

So I opened an .INO file in a plain text editor and discovered that it's nothing more than the source of my sketch.

Which means that the IDE is storing the board, com port, etc. somewhere else. Where is this data stored, so I can share it as well, and why is there not an option in the IDE to place it in the same folder as the .INO file?

It doesn't remember board on a per-sketch basis. It remembers the last board used on that instance of the ide

dgnuff:
Which means that the IDE is storing the board, com port, etc. somewhere else. Where is this data stored,

preferences.txt in the Arduino15 folder, which is found at:
You can find the location of your Arduino15 folder at the line following File > Preferences > More preferences can be edited directly in the file.

On Mac OS X:
/Users/{username}/Library/Arduino15

On Windows:
Arduino IDE 1.6.5r5 and previous:
C:\Users{username}\AppData\Roaming\Arduino15
Arduino IDE 1.6.6 and later:
C:\Users{username}\AppData\Local\Arduino15

On Linux:
/home/{username}/.arduino15 (a.k.a. ~/.arduino15)

I believe some of the above folders may be hidden.

If you're running the Arduino IDE in Portable Mode then the folder named portable inside the Arduino IDE installation folder will be used

Arduino Web Editor does store per-sketch metadata but the standard IDE does not. This feature has already been requested many times.