LetThemChat is the web app at letthemchat.com, with the iPhone app on its way. Same sign-in, same discussions, same projects and tickets. A discussion started on your Mac is readable in the browser; a question asked there is on your Mac when you sit down.
What travels
The transcript, the verdicts and receipts, pins, ratings, the ticket's fields, folders and projects, and — for a discussion the Mac ran — the workspace it worked in, so a discussion read away from the Mac says which repository it is about.
What does not
Your files. The web and the phone have no checkout of their own. They can read what the room quoted and what it ran; they cannot open the rest of your tree.
Asking there
Ask a question on the web or the phone and the room answers there — a full discussion with the same seats and the same review, minus the hands. That is the right tool for a question, a review of something already written, or thinking out loud.
For anything that needs the checkout, hand it to your Mac.