I love google home and use it for quite many applications like music, my room lights, alarm, current time, reminders, bluetooth connection, etc. Quite a lot of great conversations happen in my room and most often I tend to forget some particular name in a conversation. I wish if google could record the conversations on the trigger of a unique word I say but thats not possible presently which I will explain below.
I made a test app and tried many approaches. You call the test action which you made and then it hears for specific intent. It records everything for about 10 sec and if the conversation did not match any intent, it does the same thing twice similarly and then exists the conversation with your action. This is called reprompts and the max value set is 2. Follow this link for reprompts. This is necessary as they want prompt replies (it should feel like a conversation!)
So we can have a short conversation record of about 10 seconds each and that too twice but this defeats the whole purpose of the same. What we can do is to connect a recorder and then trigger a command to start and stop it just like the bulb! Its a shame though we cannot use the built in recorded for the same!
If anyone gets a workaround that — mail me at firstname.lastname@example.org. Eagerly waiting for the same!