I know this thread is about a year old, but I think it's got enough good info to bump it back up to the top. We've got an August lock, and the auto-unlock feature leaves a LOT to be desired (it unlocks the door when I arrive home only about 1/3 of the time, and that's being generous). Having all this technology just on the other side of the door but still having to fumble for my keys or find the app on my phone was really aggravating. Using the information in this thread, I now have an NFC tag solution that works perfectly without even unlocking my phone (if someone gets as far as our front door and wants in, they're coming in whether they have my phone or not). I just tap the phone on the tag and the door locks/unlocks automatically.
I wanted to call special attention to the following folks for their invaluable advice in this thread:
- @spalexander68 for recommending NFC Tasks/NFC Tools Pro in reply #2. Works beautifully, and NFC Tools Pro is very fairly priced!
- @mark.cockcroft for the advice in reply #44 about using the Maker API combined with a virtual button and Button Controller app.
- @lpakula for the tip in post #45 about user variables in NFC Tasks and the GET task in NFC Tools.
Using all three of these ideas, I did the following:
- Created a virtual button in Hubitat.
- Set up a Button Controller with an IF/ELSE rule that locks/unlocks the door when the "button" is pressed, depending on whether it's currently locked or not.
- Used the Maker API app to create an endpoint that (locally only) can control that virtual button and send a device command when called.
- Used NFC Tasks to create a series of user variables (base local URL for the Hubitat, Maker app ID, virtual button ID, and OAuth token).
- Used NFC Tools Pro to set up an NFC tag (cheap pack from Amazon) to trigger a GET task using the "Send Device Command" URL from the Maker app, substituting the above variables so that only devices with all of the variables (most importantly the OAuth token) set up in NFC Tasks can trigger the virtual button press that locks/unlocks the door.
Maybe it goes without saying, but the above assumes you already have the August lock set up as a device in Hubitat. I may have missed a detail or two, but I wanted to (a) recap my success in the hope that it could help someone else and (b) thank those whose advice in this thread was crucial to getting this working. 
