Groups and sharing
Everything is private when you make it, and sharing is a deliberate act aimed at somebody.
Why it landed first
One firm, several clients, one organisation
A surveying practice does not do one job. It does a lighting audit for one council, a drainage survey for a second and a site for a private developer, often with overlapping people, and it holds all of it in one organisation because that is what an organisation is. Make everything visible to every member and you have not built a simple permission model, you have built a way for one client’s data to be read by somebody working for another.
So sharing is a boundary from the start rather than something added once there was something to share. It is also the single most expensive thing to retrofit: after items exist, adding a scope means migrating every item’s permissions and re-deciding every historic sharing decision, with nobody left who remembers what was intended.
How it works
Private on creation, and groups are the unit
Everything you make starts private to you. Nothing is shared by being uploaded, by being in an organisation, or by somebody joining one: accepting an invitation gets you a membership and not a view of anybody’s work.
You share with a group, which is a named set of people you maintain, or with the whole organisation if that suits the item. A group is the right unit because it survives staff changes: the person who joins the drainage crew in March sees the drainage work, and nobody re-does a dozen individual shares to make that happen. An organisation can switch org-wide sharing off entirely, so group-scoped is the only option available in it.
For a cloud project this is what publishes it to the crew. A project is private to the manager who uploaded it until they share it, so contributors do not find half-built jobs on their phones, and the sync service applies the same rule rather than merely hiding things from a list.
The line that is not negotiable
Some things can never be public
The team activity board names individuals and shows their working patterns. There is no setting that makes it public, and that is a property of what it is rather than a permission anybody can relax in a hurry. A public link to that page would be a breach waiting for somebody to paste a URL into the wrong window.
Published layers are a different matter and will carry their own choice of private, link or public when publishing outside the organisation arrives. That is not built, and it is the point at which a deliberate, recorded, revocable act is exactly what you want.
Worth knowing
What it does not do
Groups do not nest
A flat list of named groups, on purpose. Nested groups are where permission models become impossible to reason about.
No per-group roles
Your role in the organisation decides what you may do; the group decides what you can see. Two questions, kept separate.
Sharing into an org is one way
It moves the item to the organisation. Withdrawing it to private later leaves it with the org rather than taking it back out.
Authoring is not a permanent key
Leave an organisation and you stop reading the content you made there. It was the firm's work, not yours to carry.